Dzikowski, R.; Paperna, I.; Diamant, A.
The parasite communities of the rabbitfish, Siganus rivulatus, were used to track multi-annual changes in the northern Gulf of Aqaba, Red Sea, in an environment subjected to ongoing anthropogenic impact. Parasitological data from these fish were collected from 1998 to 2000, with spring and fall samplings at three locations: at a coral reef (OBS), at a sandy beach area (NB) and at a mariculture cage farm (FF). These data were compared with data from 1995-1997 as well as data collected during 1981-1985 at the coral reef sampling site. The data analyses indicate that the ratio between heteroxenous and monoxenous parasite species declined significantly at all sites between 1995-1997 and 1998-2000. During the same period, the species richness of monoxenous parasites increased significantly at all sites. The species richness of heteroxenous parasites decreased significantly at the coral reef site, but remained steady at the other two sites. This coincided with a significant increase in the prevalence of monogeneans at the OBS and FF sites and a significant decrease in the prevalence of digeneans at the FF and NB sites. The decline in the abundance of the latter, specifically of Opisthogonoporoides sp. and Gyliauchen sp., was even more significant when compared with the 1981-1985 data. The prevalence of other gut helminths, namely the digenean Hexangium sigani and the nematodes Cucullanus sigani and Procamallanus elatensis, however, showed a significant increase over the same period. Analysis of the species richness and diversity indices of the parasite communities did not reveal conspicuous differences. These, however, did become apparent when heteroxenous and monoxenous members of particular taxa were analyzed separately. Therefore, when using parasite assemblages to detect ecological changes, it is essential to analyze not only at the community level, but also to consider separate components of particular parasitic groups.
Full Text Available In hermaphroditic helminth parasites, infrapopulation size or mating group size mostly affects some processes acting within the infrapopulation. Here, 30 natural infrapopulations (12-154 individuals of the intestinal trematode Gyliauchen volubilis Nagaty, 1956 from the fish Siganus rivulatus consisting of newly excysted juveniles, immature and mature worms were found distributed in a well-defined fundamental niche (anterior 40 % of the intestine. In small infrapopulations, all stages of the parasite were alive. In larger infrapopulations, differential mortality was only and consistently observed among newly excysted juveniles, and gradually increased to include most or all juveniles in the largest infrapopulations. Among mature worms, the mean worm length seemed unaffected by the infrapopulation size. However, the ratio mean testis size-mean ovary size, a reliable indicator of resource allocation to the male function and of opportunities for crossfertilization, significantly increased with mating group size. In small infrapopulations, all stages of the parasite were scattered along the niche, and never seen in mating pairs (possibly reproduced by selffertilization. In larger infrapopulations, newly excysted juveniles and immature worms were scattered along the anterior two thirds of the niche, while mature worms were constantly found aggregated in its posterior third (narrow microhabitat, where some were arranged in mating pairs. The probability of mating reciprocally or unilaterally was dependent on body size. The mean number of uterine eggs per worm significantly decreased and their mean sizes significantly increased with mating group size. The results are statistically significant and suggest that infrapopulation self-regulation is greatly associated with its size.
The reproductive biology of the white-spotted rabbitfish, Siganus canaliculatus, was studied on the Arabian Sea coast of Oman between April 2005 and March 2007. The males matured (L50) at 22.6 cm and females attained maturity at 23.9 cm TL when both were close to one year of age. The population of S. canaliculatus ...
Full Text Available Most of our knowledge regarding the biodiversity of gut microbes comes from terrestrial organisms or marine species of economic value, with less emphasis on ecologically important species. Here we investigate the bacterial composition associated with the gut of Siganus fuscescens, a rabbitfish that plays an important ecological role in coastal ecosystems by consuming seaweeds. Members of Firmicutes, Bacteroidetes and delta-Proteobacteria were among the dominant taxa across samples taken from the contents and the walls (sites of the midgut and hindgut (location. Despite the high variability among individual fish, we observed statistically significant differences in beta-diversity between gut sites and gut locations. Some bacterial taxa low in abundance in the midgut content (e.g., Desulfovibrio were found in greater abundances on the midgut wall and within the hindgut, suggesting that the gut may select for specific groups of environmental and/or food-associated microorganisms. In contrast, some distinct taxa present in the midgut content (e.g., Synechococcus were noticeably reduced in the midgut wall and hindgut, and are thus likely to be representative of transient microbiota. This is the first assessment of the bacterial diversity associated with the gut of S. fuscescens and highlights the need to consider the variability across different gut locations and sites when analyzing fish gut microbiomes.
Guo, Zhiqiang; Zhang, Wei; Du, Sen; Zhou, Yanyan; Gao, Na; Zhang, Li; Green, Iain
Waterborne metal uptake has been extensively studied and dietary metal assimilation is increasingly recognized in fish, whilst the interaction between the two uptake routes is largely overlooked. This study compared the waterborne Cu bioaccumulation ("6"5Cu as tracer) in a juvenile rabbitfish at different feeding regimes (starvation (SG), feeding normal diet (NDG) or diet supplemented with extra Cu (DCG)) to test the hypothesis that feeding can influence waterborne metal uptake in marine fish. NDG and DCG diet was fed as a single meal and then all fish were exposed to waterborne "6"5Cu for 48 h, during which the time course sampling was conducted to determine "6"5Cu bioaccumulation, chyme flow and dietary Cu assimilation. The results revealed that SG fish accumulated the highest "6"5Cu, followed by NDG (61% of SG), whilst DCG fish accumulated the lowest "6"5Cu (34% of SG). These results suggested a protective effect of feeding against waterborne Cu bioaccumulation. This effect was most notable between 10 min and 16 h when there was chyme in gastrointestinal tract (GT). Dietary Cu assimilation mainly occurred before 16 h after feeding. Waterborne "6"5Cu influx rate in the GT was positively correlated with "6"5Cu contents of chyme in NDG, whereas it was largely negatively correlated with "6"5Cu contents of chyme in DCG. The waterborne Cu uptake in the GT was mainly influenced by the chyme flow and dietary Cu assimilation. Overall, our findings suggested that feeding has an important effect on waterborne metal uptake and that both the feeding status of the fish and the relative metal exposure through water and food should be considered in prediction of the metal bioaccumulation and biomonitoring programs. - Highlights: • Feeding shows a protective effect against waterborne Cu uptake in fish. • The elevated dietary Cu can greatly suppress the waterborne Cu uptake. • The presence of chyme reduces Cu uptake in the gastrointestinal tract. • Feeding status has
Ravago-Gotanco, Rachel; de la Cruz, Talna Lorena; Pante, Ma Josefa; Borsa, Philippe
The taxonomy of the mottled rabbitfish Siganus fuscescens species complex has long been challenging. In this study, we analyzed microsatellite genotypes, mitochondrial lineages, and morphometric data from 373 S. fuscescens individuals sampled from the northern Philippines and Hong Kong (South China Sea, Philippine Sea and Sulu Sea basins), to examine putative species boundaries in samples comprising three co-occurring mitochondrial lineages previously reported to characterize S. fuscescens (Clade A and Clade B) or S. canaliculatus (Clade C). We report the existence of two cryptic species within S. fuscescens in the northeast region of the South China Sea and northern Philippine Sea, supported by genetic and morphological differences. Individual-based assignment methods recovered concordant groupings of individuals into two nuclear genotype clusters (Cluster 1, Cluster 2) with (1) limited gene flow, if any, between them (FST = 0.241; P South China Sea. Mitonuclear discordance due to introgression obscures phylogenetic relationships for recently-diverged lineages, and cautions against the use of mitochondrial markers alone for species identification within the mottled rabbitfish species complex in the South China Sea region.
Kiper, Ilkser Erdem; Bloomer, Paulette; Borsa, Philippe; Hoareau, Thierry Bernard
Rabbitfishes are reef-associated fishes that support local fisheries throughout the Indo-West Pacific region. Sound management of the resource requires the development of molecular tools for appropriate stock delimitation of the different species in the family. Microsatellite markers were developed for the cordonnier, Siganus sutor, and their potential for cross-amplification was investigated in 12 congeneric species. A library of 792 repeat-containing sequences was built. Nineteen sets of newly developed primers, and 14 universal finfish microsatellites were tested in S. sutor. Amplification success of the 19 Siganus-specific markers ranged from 32 to 79% in the 12 other Siganus species, slightly decreasing when the genetic distance of the target species to S. sutor increased. Seventeen of these markers were polymorphic in S. sutor and were further assayed in S. luridus, S. rivulatus, and S. spinus, of which respectively 9, 10 and 8 were polymorphic. Statistical power analysis and an analysis of molecular variance showed that subtle genetic differentiation can be detected using these markers, highlighting their utility for the study of genetic diversity and population genetic structure in rabbitfishes.
somatic index, fecundity, sex ratio. Abstract—The ... canaliculatus spawned twice a year, with major activity during November-February and minor activity ..... at 18 cm SL in Singapore (Soh, 1976, cited by ... Al-Habsi S (2009b) Biology, stock.
Fox, R. J.; Bellwood, D. R.
Niche theory predicts that coexisting species minimise competition by evolving morphological or behavioural specialisations that allow them to spread out along resource axes such as space, diet and temporal activity. These specialisations define how a species interacts with its environment and, by extension, determine its functional role. Here, we examine the feeding niche of three species of coral reef-dwelling rabbitfishes (Siganidae, Siganus). By comparing aspects of their feeding behaviour (bite location, bite rate, foraging distance) with that of representative species from two other abundant herbivorous fish families, the parrotfishes (Labridae, Scarus) and surgeonfishes (Acanthuridae, Acanthurus), we examine whether rabbitfishes have a feeding niche distinct from other members of the herbivore guild. Measurements of the penetration of the fishes' snouts and bodies into reef concavities when feeding revealed that rabbitfish fed to a greater degree from reef crevices and interstices than other herbivores. There was just a 40 % overlap in the penetration-depth niche between rabbitfish and surgeonfish and a 45 % overlap between rabbitfish and parrotfish, compared with the almost complete niche overlap (95 %) recorded for parrotfish and surgeonfish along this spatial niche axis. Aspects of the morphology of rabbitfish which may contribute to this niche segregation include a comparatively longer, narrower snout and narrower head. Our results suggest that sympatric coexistence of rabbitfish and other reef herbivores is facilitated by segregation along a spatial (and potentially dietary) axis. This segregation results in a unique functional role for rabbitfishes among roving herbivores that of "crevice-browser": a group that specifically feeds on crevice-dwelling algal or benthic organisms. This functional trait may have implications for reef ecosystem processes in terms of controlling the successional development of crevice-based algal communities, reducing their
You, Cuihong; Zeng, Fangui; Wang, Shuqi; Li, Yuanyou
The decomposition of a large amount of unexploited macroalgal resource along the coast of China often results in heavy environmental pollution. In order to pave a way of using macroalgae as the dietary ingredient of rabbitfish Siganus canaliculatus, one of a few farmed herbivorous marine teleosts in China, its preference (feeding selectivity) for different macroalgae was determined in this study. Seven seaweed species abundantly inhabiting the coast of east Guangdong Province were exposed simultaneously to rabbitfish juveniles in laboratory (multiple-choice feeding) with their content and absolute intake assayed. It was found that the most preferred algae were Ulva prolifera, Gracilaria lemaneiformis and Chaetomorpha linum, less preferred algae were U. pertusa and Porphyra haitanensis, and least preferred ones were Sargassum fusiforme and Corallina sessilis. Such an order did not change when one to four relatively preferred seaweeds were removed. The preferred seaweeds were richer in protein and soluble sugar thus higher in energy than the least preferred. In addition, this fish was found to favor filamentous and flat algae rather than calcified ones. Accordingly, the richness of nutrients and morphological characteristics determined the preference of S. canaliculatus for tested macroalgae.
Park, Yong-Ju; Park, Ji-Gweon; Jeong, Hyung-Bok; Takeuchi, Yuki; Kim, Se-Jae; Lee, Young-Don; Takemura, Akihiro
The golden rabbitfish, Siganus guttatus, is a reef fish exhibiting a restricted lunar-related rhythm in behavior and reproduction. Here, to understand the circadian rhythm of this lunar-synchronized spawner, a melatonin receptor subtype-Mel(1c)-was cloned. The full-length Mel(1c) melatonin receptor cDNA comprised 1747 bp with a single open reading frame (1062 bp) that encodes a 353-amino acid protein, which included 7 presumed transmembrane domains. Real-time PCR revealed high Mel(1c) mRNA expression in the retina and brain but not in the peripheral tissues. When the fish were reared under light/dark (LD 12:12) conditions, Mel(1c) mRNA in the retina and brain was expressed with daily variations and increased during nighttime. Similar variations were noted under constant conditions, suggesting that Mel(1c) mRNA expression is regulated by the circadian clock system. Daily variations of Mel(1c) mRNA expression with a peak at zeitgeber time (ZT) 12 were observed in the cultured pineal gland under LD 12:12. Exposure of the cultured pineal gland to light at ZT17 resulted in a decrease in Mel(1c) mRNA expression. When light was obstructed at ZT5, the opposite effect was obtained. These results suggest that light exerts certain effects on Mel(1c) mRNA expression directly or indirectly through melatonin actions.
Welsh, J. Q.; Bellwood, D. R.
Herbivorous reef fish play an important role in shaping ecosystem processes on coral reefs. Often found in schools, Scarus rivulatus, is an abundant herbivorous species on the Great Barrier Reef (GBR), Australia, especially on inshore reefs. Recent evidence has highlighted the limited spatial movements of some herbivorous fishes. However, individuals in schools are thought to be much more mobile. The aim of this study, therefore, was to evaluate the spatial range of schooling S. rivulatus to measure the spatial scale over which they exert their functional role. Furthermore, we assess the influence of the schooling behaviour on their feeding rates and thus their ecological impact. The diurnal movements of S. rivulatus were monitored using acoustic transmitters and a passive acoustic array for up to 7 months in Pioneer Bay, Orpheus Island, GBR. In addition, behavioural observations recorded school size-frequency distributions and feeding rates of S. rivulatus inside and outside foraging schools. Despite schooling, all S. rivulatus were site attached. On average, the maximum potential home range of individuals was 24,440 m2 and ranges overlapped extensively in individuals captured from the same school. School size was highly variable, with a mean school size of 5.7 individuals. Schooling had a significant impact on the functional role of individuals, with feeding rates in schools being two times higher for S. rivulatus and over three times higher for other scarid species. Our results suggest that, despite schooling, individual S. rivulatus only rove over a limited area of reef (occupying a linear stretch of reef, measuring only approximately 250 m for individuals and 220 m for entire schools). Each individual may therefore have little impact on the spatial resilience of coral reefs.
Raikhlin-Eisenkraft, Bianca; Bentur, Yedidia
Ciguatera poisoning is the commonest fish-borne seafood intoxication. It is endemic to warm water tropical areas and is caused by consumption of bottom-dwelling shore reef fish, mostly during spring and summer. The causative agent, ciguatoxin, is a heat-stable ester complex that becomes concentrated in fish feeding on toxic dinoflagellates. The common clinical manifestations are a combination of gastrointestinal and neurologic symptoms. Severe poisoning may be associated with seizures and respiratory paralysis. To describe a series of patients who sustained ciguatera poisoning in an uncommon region and from an unexpected source. Two families complained of a sensation of "electrical currents," tremors, muscle cramps, nightmares, hallucinations, agitation, anxiety and nausea of varying severity several hours after consuming rabbitfish ("aras"). These symptoms lasted between 12 and 30 hours and resolved completely. The temporal relationship to a summer fish meal, the typical clinical manifestations along with the known feeding pattern of the rabbitfish suggested ciguatera poisoning. The Eastern Mediterranean basin is an unusual region and the rabbitfish an unusual source for ciguatera poisoning. There are no readily available and reliable means for detecting ciguatoxin in humans. A high index of suspicion is needed for diagnosis and a thorough differential diagnosis is essential to eliminate other poisonings, decompression sickness and encephalitis. Supportive therapy is the mainstay of treatment.
Full Text Available Rabbitfish Siganus canaliculatus is ones of coral reef inhabitants are exploited intensively and suspected population decline so the necessary management measures was needed. The study aims to analyze aspects of the dynamics of rabbit fish populations in the Bone Gulf Luwu waters. Data was collected by Staratied Random Sampling estimation of the size structure the number of age groups and average length of fish per age group use a column diagram and Bhattacharya method. Population growth is analyzed using the Von Bertalanffy equation exponential growth the value of L K by Ford and Walford method and t0 by Pauly method. The total mortality fishing mortality the rate of exploitation and Y R were estimated by methods of Beverton and Holt and natural mortality by method of Pauly. The results showed that the population of rabbit fish in the waters of the Gulf of Bone Luwu consists of five age groups has the average length and the lenth range of 8.0904 cm and 5.7 to 9.0 cm on the relative age of one year 10.9222 cm and 9.0 to 12.3 cm on the relative age of two years from 12.3 to 15.6 cm 14.1543 cm on the relative age of three years 16.8949 cm and 15.6 to 18.9 cm on the relative age four years and 19.4906 cm and 18.9 to 20.7 cm on the relative age of five years. Maximum length Lamp8734 of 30.5814 cm and the growth rate coefficient K of 0.1572 per year while the t0 value of -1.4815 ofyear. The total mortality Z of 1.6913 per year the mortality M of 0.6109 fishing mortality t 1.0804 per year the rate of exploitation E of 0.6388 and optimal exploitation rate Eopt of 0.50 the value of Y R is now 0.0127 and the value of Y R optimal 0.0150. The conclusion that the population is dominated medium sized fish slow population growth as a result of the high mortality rate of the capture and exploitation as well as the recruitment process is not optimal.
Wijkmark Nicklas, Kullander, Sven O.; Barriga Ramiro
Andinocara blombergi, nueva especie, es descrito del río Esmeraldas, cuenca hidrográfica ubicada al noroeste del Ecuador. Se diferencia de la especie similar A. rivulatus (Günther, 1860) por tener 25 escamas vs. 24 escamas presentes en la escala de la línea E1, promedios merísticos ligeramente superiores, cabeza menos ancha y menor espacio interorbital. Andinocara rivulatus se redescribe en base a especímenes de la cuenca del río Guayas, Túmbes y Zarumilla, drenajes del Ecuador y Perú. Aequid...
Batang, Zenon B.; Mannalamkunnath Alikunhi, Nabeel; Gochfeld, Michael; Burger, Joanna; Aljahdali, Ramzi; Al-Jahdali, Haitham; Aziz, Mohammed A.M.; Al-Jebreen, Dalal; Al-Suwailem, Abdulaziz M.
chlorinated homologs, mainly hexachlorobiphenyls, but less chlorinated congeners were also consistently elevated, notably in Siganus rivulatus (Area III) and Mugil cephalus (Area I). It remains to be ascertained if the latter were breakdown products or due
Zhang, Xinxu; Wu, Huijuan; Li, Zhongzhen; Li, Yuanyou; Wang, Shuqi; Zhu, Dashi; Wen, Xiaobo; Li, Shengkang
Fishes represent the highest diversity of vertebrates; however, our understanding of the compositions and functions of their gut microbiota is limited. In this study, we provided the first insight into the gut microbiota of the herbivorous fish Siganus canaliculatus by using three molecular ecology techniques based on the 16S rRNA genes (denaturing gradient gel electrophoresis, clone library construction, and highthroughput Illumina sequencing), and the Illumina sequencing technique is suggested here due to its higher overall coverage of the total 16S rRNA genes. A core gut microbiota of 29 bacterial groups, covering >99.9% of the total bacterial community, was found to be dominated by Proteobacteria and Firmicutes in fish fed three different diets with/without the supplementation of Ulva pertusa and non-starch polysaccharide (NSP) enzymes (cellulase, xylanase, and β-glucanase). Diverse potential NSP-degrading bacteria and probiotics (e.g., Ruminococcus, Clostridium and Lachnospiraceae) were detected in the intestine of the fish fed U. pertusa, suggesting that these microorganisms likely participated in the degradation of NSPs derived from U. pertusa. This study supports our previous conclusion that U. pertusa-based diets are suitable for the production of S. canaliculatus with lower costs without compromising quality.
Priest, Mark; Halford, Andrew R; McIlwain, Jennifer L
We used microsatellite markers to assess the population genetic structure of the scribbled rabbitfish Siganus spinus in the western Pacific. This species is a culturally important food fish in the Mariana Archipelago and subject to high fishing
Philip Teguh Imanto
Full Text Available Beronang lada (Siganus canaliculatus adalah kelompok ikan yang banyak ditemukan di perairan pantai dan rataan terumbu karang, memiliki nilai ekonomis yang cukup tinggi terutama pada saat hari raya Imlek, di mana ikan yang matang gonad sangat digemari dan mencapai harga tertinggi hingga Rp 110 ribu/kg. Hal ini menarik minat pembudidaya untuk memelihara dan membesarkan dengan tujuan mencapai ukuran matang gonad pada saat tersebut. Ketersediaan benih yang melimpah dan mudah diperoleh menyebabkan pengusaha memelihara dengan kepadatan tinggi hingga 5 ribu ekor per kurungan berukuran 3 m x 3 m x 2 m (18 m3, dengan sediaan pakan potongan padang lamun dan pelet kakap komersial seri KPA 3-4. Kendala kematian benih yang cukup tinggi muncul pada saat pemeliharaan, yang dicirikan dengan gerakan abnormal, mulut kemerahan, dan ekor yang terkikis. Pengamatan lapang dilakukan pada fasilitas pemeliharaan dan wawancara untuk mendapat gambaran umum kondisi budidaya, serta pengambilan sampel benih sehat dan yang bermasalah untuk observasi visual (organoleptik maupun secara mikroskopik. Hasil pengamatan dengan miksroskop diketahui mulut yang memerah disebabkan kerusakan pada gigi dan bibir, serta ekor yang terkikis lebih disebabkan gigitan benih ikan yang sehat. Perbaikan manajemen budidaya disarankan dilakukan dengan mengurangi tingkat kepadatan, penggunaan pelet basah (moist pellet serta meningkatkan frekuensi pemberian pakan diharapkan dapat membantu mengatasi permasalahan.
Crude oil from fields in the Persian Gulf and in the Sinai plus a chemical oil dispersant were tested, using static bioassay procedures, for toxicity to adults or juveniles of ten marine species: Heteroxenia fuscescens, a soft coral; Nerita forskali and Drupa granulata, gastropod molluscs; Mytilus variabilis, a mussel; Acanthopleura haddoni, a chiton (mollusc); Echinometra mathaei, sea urchin; Calcinus latens, a hermit crab; Palaemon pacificus, a shrimp; Parupeneus barberinus, goatfish; and Siganus rivulatus, rabbitfish. Concentrations fatal to 50 percent of individual test species in 168 hours, LC-50 (168 h), ranged from 0.74 to more than 30.0 ml/liter for Persian Gulf crude, from 14.5 to more than 30.0 ml/liter for Sinai crude, and from 0.006 to 0.064 ml/liter for the dispersant. In general, fishes and crustaceans were the most sensitive groups assayed and molluscs the most resistant. LC-50 (168 h) values for oil-dispersant mixtures of 10 parts oil to 1 part dispersant (v/v) for selected species ranged from 0.047 to 0.152 ml/liter which appears to reflect the biocidal properties of the dispersant. Some individuals that survived immersion in high concentrations of the test compounds for 168 h were adversely affected during treatment and afterwards.
Bentur, Yedidia; Spanier, Ehud
The consumption of edible fish (e.g., Siganus spp) was assumed to have caused ciguatera poisoning at an atypical site, the eastern Mediterranean. This pilot study assesses the presence of ciguatoxin-like substances in edible fish on the eastern Mediterranean coast of Israel. Samples of Siganus rivulatus from polluted seawater (Haifa Bay), Siganus rivulatus from relatively clean seawater (Dor), and fish from the freshwater Sea of Galilee not inhabited by toxic algae were analyzed during summertime. Ciguatoxin-like substances were tested by a membrane immunobead assay that yields a color reaction (positive, weakly positive, negative). Significantly more large and small fish from Haifa Bay yielded positive color reactions compared to fish from Dor. Sea of Galilee fish gave no positive color reactions. Our results suggest the presence of ciguatoxin-like substances in edible fish of the eastern Mediterranean. Additional analyses are needed to determine whether these substances are ciguatoxins or related polyethers.
reproductive biology of the rabbit fish Siganus sutor (Valenciennes 1835). Trap catch ... way to facilitate sustainable exploitation of the rabbitfishes and other reef fishes in the DMRs. ... abundance of target species manifested by decreases in sizes and catch per unit effort (CPUE) within ... MATERIALS AND METHODS.
Borell, E. M.; Steinke, M.; Fine, M.
Grazing on marine macroalgae is a key structuring process for coral reef communities. However, ocean acidification from rising atmospheric CO2 concentrations is predicted to adversely affect many marine animals, while seaweed communities may benefit and prosper. We tested how exposure to different pCO2 (400, 1,800 and 4,000 μatm) may affect grazing on the green alga Ulva lactuca by herbivorous fish and sea urchins from the coral reefs in the northern Gulf of Aqaba (Red Sea), either directly, by changing herbivore behaviour, or indirectly via changes in algal palatability. We also determined the effects of pCO2 on algal tissue concentrations of protein and the grazing-deterrent secondary metabolite dimethylsulfoniopropionate (DMSP). Grazing preferences and overall consumption were tested in a series of multiple-choice feeding experiments in the laboratory and in situ following exposure for 14 d (algae) and 28 d (herbivores). 4,000 μatm had a significant effect on the biochemical composition and palatability of U. lactuca. No effects were observed at 1,800 relative to 400 μatm (control). Exposure of U. lactuca to 4,000 μatm resulted in a significant decrease in protein and increase in DMSP concentration. This coincided with a reduced preference for these algae by the sea urchin Tripneustes gratilla and different herbivorous fish species in situ (Acanthuridae, Siganidae and Pomacanthidae). No feeding preferences were observed for the rabbitfish Siganus rivulatus under laboratory conditions. Exposure to elevated pCO2 had no direct effect on the overall algal consumption by T. gratilla and S. rivulatus. Our results show that CO2 has the potential to alter algal palatability to different herbivores which could have important implications for algal abundance and coral community structure. The fact that pCO2 effects were observed only at a pCO2 of 4,000 μatm, however, indicates that algal-grazer interactions may be resistant to predicted pCO2 concentrations in the
The new records of alien species include: the red algae Antithamnionella elegans and Palisada maris-rubri, found for the first time in Israel and Greece respectively; the green alga Codium parvulum reported from Turkey (Aegean Sea; the first record of the alien sea urchin Diadema setosum in Greece; the nudibranch Goniobranchus annulatus reported from South-Eastern Aegean Sea (Greece; the opisthobranch Melibe viridis found in Lebanon; the new records of the blue spotted cornetfish Fistularia commersonii in the Alicante coast (Eastern Spain; the alien fish Siganus luridus and Siganus rivulatus in Lipsi Island, Dodecanese (Greece; the first record of Stephanolepis diaspros from the Egadi Islands Marine Protected Area (western Sicily; a northward expansion of the alien pufferfish Torquigener flavimaculosus along the southeastern Aegean coasts of Turkey; and data on the occurrence of the Lessepsian immigrants Alepes djedaba, Lagocephalus sceleratus and Fistularia commersonii in Zakynthos Island (SE Ionian Sea, Greece.
Full Text Available This is the first work establishing a base-line data of the level of total Polychlorinated Biphenyl (PCB contaminants in selected marine organisms (Siganus rivulatus, Mullet spp., and oysters and its relationship to organism size and the harvest distance from the oil spill source. Six locations across the Lebanese Mediterranean were included for sampling. Oysters and the two fish types were collected after 72 days of the spill. The length, maximum width, and whole weight of individual organisms were recorded. Methanol extracts of the samples were analyzed for total PCB using a Competitive Enzyme-linked Immunosorbent Assay (ELISA based Spectrophotometry.All means of PCB in the three selected marine organisms were below the guidance level set by USFDA (2 ppm. A total of 6 significant regression equations were established between the total PCB level and certain size dimensions of specific selected marine species, with values of R2 ranging between 0.719 – 0.909 and P values ranging from 0.038 – 0.099.In addition, the total PCB level in Siganus rivulatus correlated with the harvest distance north of the oil spill source, signifying a drop in total PCB level with an increase in harvest distance from the oil spill source.
Full Text Available The presence of marine alien species in El-Kouf National Park and the neighbouring areas was assessed using a compilation of available information and observations, a field survey conducted on October 2010 in the framework of the MedMPAnet project and results of further monitoring during June and September 2012. A total of 9 alien species were reported: the Rhodophyta Asparagopsis taxiformis (Delile Trevisan de Saint-Léon, the Chlorophyta Caulerpa racemosa var. cylindracea (Sonder Verlaque, Huisman & Boudouresque, the crab Percnon gibbesi (H. Milne-Edwards, 1853 and the fishes Fistularia commersonii Rüppell, 1838, Siganus luridus (Rüppell, 1829, Siganus rivulatus Forsskål, 1775, Pempheris vanicolensis Cuvier, 1831, Lagocephalus sceleratus (Gmelin, 1789 and Sphyraena flavicauda Rüppell, 1838. Several of them were until now unknown for the National Park. The list of alien marine species of Libya is updated and discussed. Until now 63 marine aliens species were recorded along the Libyan coasts. These include 3 Foraminifera, 3 Ochrophyta, 5 Rhodophyta, 5 Chlorophyta, 1 Magnoliophyta, 11 Arthropoda, 13 Mollusca, 1 Echinodermata and 21 Chordata. Among these Non Indigenous Species, 43 are known as established along the Libyan coast including 8 invasive, 11 casual, 6 questionable, 3 cryptogenic and 1 unknown. An in-depth study of the marine organisms would substantially increase the number of alien species occurring in Libya. Monitoring of marine assemblages of MPAs is a valuable opportunity to go further into the knowledge of native and introduced species.
Full Text Available An updated inventory of alien marine species from coastal and offshore waters of Cyprus is presented. Records were compiled based on the existing scientific and grey literature, including HCMR database of Mediterranean alien species, technical reports, scientific congresses, academic dissertations, and websites, as well as on unpublished/personal observations. The listed species were classified in one of five categories: established, invasive, casual, cryptogenic, and questionable. The mode of introduction and the year of first sighting were also reported for each species. Eight new records based on personal observations of the authors were reported (Chondria coerulescens, Neosiphonia sphaerocarpa, Enchelycore anatina, Lagocephalus spadiceus, Lagocephalus suezensis, Scomberomorus commerson, Sillago sihama, and Sphoeroides pachygaster. Nine species, previously reported as aliens in Cypriot waters, were excluded from the inventory for various reasons. Ten established species were characterized as invasive (Caulerpa racemosa var. cylindracea, Cerithium scabridum, Strombus persicus, Trochus erythraeus, Brachidontes pharaonis, Pinctada radiata, Fistularia commersonii, Lagocephalus sceleratus, Siganus luridus, and Siganus rivulatus as they have a substantial impact on biodiversity and/or local economy. The impact of alien marine species in Cyprus is expected to grow in the close future, and further effort directed towards recording alien invasions and their impact will be needed.
Peng, Xiaoyan; Liu, Fengjie; Wang, Wen-Xiong
Low mercury (Hg) concentrations down to several nanograms Hg per gram of wet tissue are documented in certain fish species such as herbivorous fish, and the underlying mechanisms remain speculative. In the present study, bioaccumulation and depuration patterns of inorganic Hg(II) and methylmercury (MeHg) in a herbivorous rabbitfish Siganus canaliculatus were investigated at organ and subcellular levels following waterborne or dietary exposures. The results showed that the efflux rate constants of Hg(II) and MeHg were 0.104 d(-1) and 0.024 d(-1) , respectively, and are probably the highest rate constants recorded in fish thus far. The dietary MeHg assimilation efficiency (68%) was much lower than those in other fish species (∼90%). The predominant distribution of MeHg in fish muscle was attributable to negligible elimination of MeHg from muscle (Hg(II) was much more slowly distributed into muscle but was efficiently eliminated by the intestine (0.13 d(-1) ). Subcellular distribution indicated that some specific membrane proteins in muscle were the primary binding pools for MeHg, and both metallothionein-like proteins and Hg-rich granules were the important components in eliminating both MeHg and Hg(II). Overall, the present study's results suggest that the low tissue Hg concentration in the rabbitfish was partly explained by its unique biokinetics. Environ Toxicol Chem 2016;35:2074-2083. © 2016 SETAC. © 2016 SETAC.
P. K. KARACHLE
Full Text Available In this Collective Article on “New Mediterranean Biodiversity Records”, we present additional records of species found in the Mediterranean Sea. These records refer to eight different countries throughout the northern part of the basin, and include 28 species, belonging to five phyla. The findings per country include the following species: Spain: Callinectes sapidus and Chelidonura fulvipunctata; Monaco: Aplysia dactylomela; Italy: Charybdis (Charybdis feriata, Carcharodon carcharias, Seriola fasciata, and Siganus rivulatus; Malta: Pomacanthus asfur; Croatia: Lagocephalus sceleratus and Pomadasys incisus; Montenegro: Lagocephalus sceleratus; Greece: Amathia (Zoobotryon verticillata, Atys cf. macandrewii, Cerithium scabridum, Chama pacifica, Dendostrea cf. folium, Ergalatax junionae, Septifer cumingii, Syphonota geographica, Syrnola fasciata, Oxyurichthys petersi, Scarus ghobban, Scorpaena maderensis, Solea aegyptiaca and Upeneus pori; Turkey: Lobotes surinamensis, Ruvettus pretiosus and Ophiocten abyssicolum. In the current article, the presence of Taractes rubescens (Jordan & Evermann, 1887 is recorded for the first time in the Mediterranean from Italy. The great contribution of citizen scientists in monitoring biodiversity records is reflected herein, as 10% of the authors are citizen scientists, and contributed 37.5% of the new findings.
Batang, Zenon B.
All 209 congeners of polychlorinated biphenyls (PCBs) in edible fish tissue from the central Red Sea coast (Jeddah region) of Saudi Arabia were analyzed by isotope dilution high-resolution gas chromatography–mass spectrometry. The upper-bound total PCB (ΣPCB) levels in nine commonly consumed fish species from three areas were 0.2–82.5 ng/g wet weight (17–8450 ng/g lipid weight), which were at the lower end of reported global range and far below international tolerance limits (500–3000 ng/g ww). Dioxin-like congeners contributed up to 12.8% (mean 6.5%) to ΣPCB in tissue samples, with the total PCB toxic equivalencies (TEQs) at a tolerable range (0.05–2.6 pg TEQ/g ww or 2–238 pg TEQ/g lw) for all species. PCB profiles were dominated by moderately chlorinated homologs, mainly hexachlorobiphenyls, but less chlorinated congeners were also consistently elevated, notably in Siganus rivulatus (Area III) and Mugil cephalus (Area I). It remains to be ascertained if the latter were breakdown products or due to fresh inputs. The top congeners based on dominance by both occurrence and abundance were identified as potential markers of ΣPCB in fish tissue, which can be used for future selective biomonitoring in case of reasonable constraints on full congener approach.
Amin, Omar M; Van Ha, Nguyen
Four species of echinorhynchid acanthocephalans were collected from marine fish off Cat Ba Island, Halong Bay, Gulf of Tonkin, Vietnam, in the spring of 2009. Acanthocephalus halongensis n. sp. (Echinorhynchidae) from the redtail scad, Decapterus kurroides Bleeker 1855 (Carangidae), has a unique proboscis armature with a spiniform basal hook with lateral root and an incomplete receptacle wall posteriorly. Gorgorhynchus tonkinensis n. sp. (Rhadinorhynchidae) also from D. kurroides, has long, slender, winding lemnisci, many epidermal nuclei, and a narrow anterior trunk with a shoulder armed with 20 circles of tightly packed spines, the posterior four circles of which have abruptly larger spines than those in the anterior circles. Neorhadinorhynchus atypicalis n. sp. (Cavisomidae) from the rabbitfish, Siganus fuscescens (Houttuyn 1782) (Siganidae), has the largest number of proboscis hooks per row, testes wider than long, and four clustered cement glands. Micracanthorhynchica kuwaitensis Amin and Sey 1996 (Rhadinorhynchidae) from the spottail needlefish Strongylura strongylura (van Hasselt 1823) (Belonidae) was similar to specimens originally described from the Arabian Gulf off the Kuwaiti coast. These acanthocephalans were collected in small numbers but stood out as uniquely and considerably different from their closest relatives to warrant their reporting. All species of acanthocephalans and their host and geographic distribution are described, and a key to the species of Gorgorhynchus is provided.
Full Text Available Yoğun zirai faaliyetlerin yapıldığı Antalya’nın batı sahillerinden yakalanan ekonomik önemi olan bazı deniz balıklarının (Diplodus sargus, Siganus rivulatus, Lithognathus mormyrus, Liza aurata, Chelon labrasus kas, deri ve solungaçlarındaki bakır, çinko, mangan, demir ve magnezyum (Genellikle zirai aktivitelerden kaynaklanırlar biyoakümülasyon seviyeleri araştırılmıştır. Balıkların dokularında incelenen elementlerin minimum ve maksimum seviyeleri (mg kg-1 yaş ağırlık bakır için 0.541.69; çinko için 4.14-407.23; mangan için 0.15-9.17; demir için 3.45-104.49 ve magnezyum için 204.33- 784.30 olarak tespit edilmiştir. İncelenen elementlerin en düşük biyoakümülasyon seviyeleri kas dokularda, en yüksek seviyeler (Bakır hariç ise solungaçlarda tespit edilmiştir. İncelenen türlerin kas dokularındaki bakır ve çinko seviyeleri (Dünya Sağlık Örgütü (WHO, Gıda ve Tarım Örgütü (FAO ve Türk Gıda Kodeksi’nde belirtilen kabul edilebilir maksimum seviyelerden daha düşük, bazı türlerin (D. sargus, S. rivulatus, L. mormyrus and L. aurata derilerinde bulunan çinko seviyeleri ise kabul edilebilir maksimum seviyelerden daha yüksek bulunmuştur
Full Text Available Rhodes Island (southeastern Aegean is located in a geographically crucial region subjected to biological invasions. Among the 108 alien species recorded, 30 are fish, all of Indo-Pacific/Red Sea origin introduced via Suez through Lessepsian migration (Corsini-Foka et al., 2015; Corsini-Foka and Kondylatos, In press; Kondylatos and Corsini-Foka, In press. In this oligotrophic area, fishery production is limited, due to the paucity of species of commercial interest and their low abundance, while adapted infrastructures for fish landing and marketing are absent. Coastal fishery has dominated during the last twenty years (ELSTAT, 2015. Within 2002-2010, the Hydrobiological Station of Rhodes conducted experimental boat seining surveys, using exclusively a professional 12m fishing boat, at 5-30 m depth, in the Gulf of Trianda (sandy mud, Posidonia meadows. The 94 carried out hauls (7-18 hauls/year, produced a total fish biomass of approximately 4400 Kg, recording 97 fish (86 native, 11 alien and 4 cephalopod species (3 native, 1 alien. Fish species ranged from 32 to 63/year, whereas aliens ranged from 5 to 8 species. Almost steadily present since 2002, were earlier colonizers such as Apogonichthyoides pharaonis, Siganus rivulatus, Siganus luridus, Stephanolepis diaspros and more recent ones as Pteragogus trispilus, Sphyraena chrysotaenia and Fistularia commersonii, while Lagocephalus sceleratus, firstly recorded in 2005, occurred regularly since 2007; the presence of Lagocephalus suezensis, Sphyraena flavicauda and Upeneus pori was scattered since their first records in 2004-2005. Alien fish commercially important are the Siganids, S. chrysotaenia and surprisingly F. commersonii. In terms of biomass per haul, alien fish ranged from 0 to 18.5 Kg, native from 1.5 to 182 Kg. Catches were dominated by Centracanthidae (Spicara spp. and Sparidae (Boops boops, sometimes by other native such as Oblada melanura, Diplodus spp., Chromis Chromis and others. The
Priest, Mark A.; Halford, Andrew R.; Clements, Kendall D.; Douglas, Emily; Abellana, Sheena L.; McIlwain, Jennifer L.
Processes acting during the early stages of coral reef fish life cycles have a disproportionate influence on their adult abundance and community structure. Higher growth rates, for example, confer a major fitness advantage in larval and juvenile fishes, with larger fish undergoing significantly less mortality. The role of dietary resources in the size-structuring process has not been well validated, especially at the early post-settlement phase, where competition and predation are seen as preeminent drivers of juvenile fish assemblage structure. Here, we report on a size differential of 10-20% between recently settled Siganus spinus rabbitfish recruits from different bays around the Pacific island of Guam. This difference was maintained across multiple recruitment events within and between years. After confirming the validity of our observations through otolith increment analysis, subsequent investigation into the drivers of this variation revealed significant differences in the structure of algal assemblages between bays, congruent with the observed differences in size of the recently settled fish. Gut analyses showed a greater presence of algal types with higher levels of nitrogen and phosphorus in the stomachs of fish from Tanguisson, the bay with the largest observed recruits. To ensure this mechanism was one of causation and not correlation, we conducted a fully factorial experiment in which S. spinus recruits sampled from different bays were reared on all combinations of algal diets representative of the different bays. Recruits on the `Tanguisson' diet grew faster than recruits on other diets, regardless of their origin. We propose that the greater availability of high-quality dietary resources at this location is likely conferring benefits that impact on the population-level dynamics of this species. The spatial and temporal extent of this process clearly implicates food as a limiting resource, capable of mediating fish population dynamics at multiple
We used microsatellite markers to assess the population genetic structure of the scribbled rabbitfish Siganus spinus in the western Pacific. This species is a culturally important food fish in the Mariana Archipelago and subject to high fishing pressure. Our primary hypothesis was to test whether the individuals resident in the southern Mariana Island chain were genetically distinct and hence should be managed as discrete stocks. In addition to spatial sampling of adults, newly-settled individuals were sampled on Guam over four recruitment events to assess the temporal stability of the observed spatial patterns, and evidence of self-recruitment. We found significant genetic structure in S. spinus across the western Pacific, with Bayesian analyses revealing three genetically distinct clusters: the southernMariana Islands, east Micronesia, and the west Pacific; with the southern Mariana Islands beingmore strongly differentiated fromthe rest of the region. Analyses of temporal samples from Guam indicated the southern Mariana cluster was stable over time, with no genetic differentiation between adults versus recruits, or between samples collected across four separate recruitment events spanning 11 months. Subsequent assignment tests indicated seven recruits had self-recruited from within the Southern Mariana Islands population. Our results confirm the relative isolation of the southern Mariana Islands population and highlight how local processes can act to isolate populations that, by virtue of their broad-scale distribution, have been subject to traditionally high gene flows. Our results add to a growing consensus that self-recruitment is a highly significant influence on the population dynamics of tropical reef fish. 2012 The Authors. Ecology and Evolution published by Blackwell Publishing Ltd.
Streit, Robert P.; Bellwood, David R.
Adult coral-reef fishes display a remarkable ability to return home after being displaced. However, we know very little about homing behaviour in juvenile fishes. Homing behaviour in juvenile fishes is of interest because it will shape subsequent spatial distributions of adult fish communities. Comparing multiple species, families and functional groups allows us to distinguish between species-specific traits and more generalised, species-independent traits that may drive homing behaviour. Using displacement experiments of up to 150 m, we quantified homing behaviour of juvenile, newly recruited reef fishes of seven species in three families, including herbivorous parrotfishes and rabbitfishes, carnivorous wrasse and planktivorous damselfishes. All species showed the ability to home successfully, but success rates differed among species. Juvenile parrotfishes were the most successful (67% returning home), while return rates in the other species ranged from 10.5% ( Siganus doliatus) to 28.9% ( Coris batuensis). However, across all species body size appeared to be the main driver of homing success, rather than species-specific traits. With every cm increase in body size, odds of returning home almost tripled (170% increase) across all species. Interestingly, the probability of getting lost was not related to body size, which suggests that mortality was not a major driver of unsuccessful homing. Homing probability halved beyond displacement distances of 10 m and then remained stable. Higher likelihood of homing over short distances may suggest that different sensory cues are used to navigate. Overall, our results suggest that homing ability is a widespread trait among juvenile reef fishes. A `sense of home' and site attachment appear to develop early during ontogeny, especially above taxon-specific size thresholds. Hence, spatial flexibility exists only in a brief window after settlement, with direct implications for subsequent patterns of connectivity and ecosystem
Parrotfishes (family Labridae: Scarini) are regarded to have important roles for maintaining the ecosystem balance in coral reefs due to their removal of organic matter and calcic substrates by grazing. The purpose of the present study was to clarify the interspecific differences in grazing ability of five parrotfish species (Chlorurus sordidus, C. bowersi, Scarus rivulatus, S. niger and S. forsteni) in relation to interspecific differences in jaw-lever mechanics and the relative weight of the adductor mandibulae (muscles operating jaw closing). The grazing ability was calculated by using stomach contents (CaCO3 weight/organic matter weight) defined as the grazing ability index (GAI). There were significant interspecific differences in GAI (C. sordidus = C. bowersi > S. rivulatus > S. niger = S. forsteni). Teeth of C. sordidus and C. bowersi were protrusive-shape whereas teeth of S. rivulatus, S. niger and S. forsteni were flat-shape. C. sordidus and C. bowersihave jaw-lever mechanics producing a greater biting force and have a larger weight of adductor mandibulae. S. rivulatus has jaw-lever mechanics producing a greater biting force but a smaller weight of adductor mandibulae that produce an intermediate biting force. In contrast, S. niger and S. forsteni have jaw-lever mechanics producing a lesser biting force and have a smaller weight of adductor mandibulae. Feeding rates and foray size of S. rivulatus, S. niger and S. forsteni were greater than C. sordidus and C. bowersi. The degree in bioerosion (GAI × feeding rate) was the largest for S. rivulatusand the smallest for S. forsteni. The degree in bioerosion for C. sordidus was larger than S. niger whereas relatively equal between C. bowersi and S. niger. These results suggest that interspecific difference in GAI was explained by interspecific differences in teeth shape, jaw-lever mechanics and relative weight of adductor mandibulae. The interspecific difference in the degree of bioerosion suggests the
The spatial patterns among fish families were attributed to a combination of differences in species abundance and distribution as well as variation in fishing effort. Spawning periodicity reported by fishers indicated that for snappers and rabbitfishes, the most activity occurred across a protracted period of October to April/May, ...
...--groupers 5,600 Holocentridae--squirrelfish......... 2,585 Mugilidae--mullets 2,857 Crustaceans--crabs 2,248...,726 Serranidae--groupers 17,958 Mugilidae--mullets 15,032 Kyphosidae--chubs/rudderfish........ 13,247...; 4,446 giant clams. Mugilidae--mullets 3,308 Siganidae--rabbitfish 2,537 Bolbometopon muricatum...
Parrotfishes (family Labridae: Scarini) are regarded to have important roles for maintaining the ecosystem balance in coral reefs due to their removal of organic matter and calcic substrates by grazing. The purpose of the present study was to clarify the interspecific differences in grazing ability of five parrotfish species (Chlorurus sordidus, C. bowersi, Scarus rivulatus, S. niger and S. forsteni) in relation to interspecific differences in jaw-lever mechanics and the relative weight of th...
Chelladurai, Gurusamy; Mohanraj, Jayaraj; Jayanthi, Govinda Rajalu
Isopod Parasites are considered as a major threat to the fishing industry, due to rigorous disease outbreaks. The parasites from the two economically important reef fish family Lutjanidae and Serranidae are analyzed i.e. Epinephelus malabaricus and Lutjanus rivulatus. The samples are obtained from the landings of Trawl net from Gulf of Mannar region of South east coast of India. They are severely infested by the isopod parasite Agrathona macronema in the Pectoral fins and ventral region of the body. This species is found to be the new record in the Gulf of Mannar region and deposited in the Marine laboratory of Kamaraj College. Length and weight of the host and parasites are measured. The parasites infested on 13 specimens of E. malabricus out of 8 and 17 out of 12 species of L. rivulatus . The prevalence of parasite on the grouper and snapper fish (61.53 and 70.58 %) and mean intensity (2.62 and 2.58 %) respectively. The prevalence was maximum in L. rivulatus and minimum in E. malbaricus may be to the host specificity. Further studies are needed to know the life cycle of the parasite, host preference, disease outbreak and its role in the coral reef ecosystem.
Full Text Available Parrotfishes (family Labridae: Scarini are regarded to have important roles for maintaining the ecosystem balance in coral reefs due to their removal of organic matter and calcic substrates by grazing. The purpose of the present study was to clarify the interspecific differences in grazing ability of five parrotfish species (Chlorurus sordidus, C. bowersi, Scarus rivulatus, S. niger and S. forsteni in relation to interspecific differences in jaw-lever mechanics and the relative weight of the adductor mandibulae (muscles operating jaw closing. The grazing ability was calculated by using stomach contents (CaCO3 weight/organic matter weight defined as the grazing ability index (GAI. There were significant interspecific differences in GAI (C. sordidus = C. bowersi > S. rivulatus > S. niger = S. forsteni. Teeth of C. sordidus and C. bowersi were protrusive-shape whereas teeth of S. rivulatus, S. niger and S. forsteni were flat-shape. C. sordidus and C. bowersihave jaw-lever mechanics producing a greater biting force and have a larger weight of adductor mandibulae. S. rivulatus has jaw-lever mechanics producing a greater biting force but a smaller weight of adductor mandibulae that produce an intermediate biting force. In contrast, S. niger and S. forsteni have jaw-lever mechanics producing a lesser biting force and have a smaller weight of adductor mandibulae. Feeding rates and foray size of S. rivulatus, S. niger and S. forsteni were greater than C. sordidus and C. bowersi. The degree in bioerosion (GAI × feeding rate was the largest for S. rivulatusand the smallest for S. forsteni. The degree in bioerosion for C. sordidus was larger than S. niger whereas relatively equal between C. bowersi and S. niger. These results suggest that interspecific difference in GAI was explained by interspecific differences in teeth shape, jaw-lever mechanics and relative weight of adductor mandibulae. The interspecific difference in the degree of bioerosion suggests
Paperna, I.; Diamant, A.; Overstreet, R. M.
Hyperinfection by the gill-infesting monogenean Allobivagina sp. (Microcotylea) caused mass mortalities in juveniles of Siganus luridus cultured in seawater earthen ponds and holding tanks in Eilat (Gulf of Aqaba, Red Sea). Other species of Siganus and adults of S. luridus cultured in the same systems acquired a low intensity of infestation. Most hyperinfected fish were emaciated and anaemic with hematocrit values below 10 %. Skin and mouth infestations by the monogenean Benedenia monticelli (Capsaloidea) caused mass mortalities in grey mullets (Mugilidae). These mortalities occurred in large individuals in wild populations of Liza carinata from lagoonal habitats in the Gulf of Suez and in most species of grey mullets cultured in Eilat. The intensity of infestation correlated positively with severity of infestation, and the common sites of infestation corresponded with areas of severe pathological alterations. Spontaneous recovery followed the climax of an epizootic, both for infested S. luridus and infested grey mullets. Decline in infestation coincided with remission of the pathological signs.
Pardo, R.; Scott, S.; Vila, I.
El género Trichomycterus incluye aproximadamente 120 especies, que se distribuyen comúnmente en las cabeceras de los ríos neotropicales. En Chile este género se encuentra ampliamente distribuido: en el altiplano (14°-22°S) Trichomycterus chungaraensis; T. laucaensis y T. rivulatus, mientras T. areolatus se distribuye entre Huasco (28° 27'S) y Chiloé (41° 27'S), presentando la mayor amplitud en extensión, y en simpatría con T. chiltoni en la cuenca del Bío Bío (36° 49'S). La diversidad de hábi...
Brandl, Simon J; Bellwood, David R
Reciprocity is frequently assumed to require complex cognitive abilities. Therefore, it has been argued that reciprocity may be restricted to animals that can meet these demands. Here, we provide evidence for the potential presence of direct reciprocity in teleost fishes. We demonstrate that in pairs of coral reef rabbitfishes (f. Siganidae), one fish frequently assumes an upright vigilance position in the water column, while the partner forages in small crevices in the reef substratum. Both behaviours are strongly coordinated and partners regularly alternate their positions, resulting in a balanced distribution of foraging activity. Compared to solitary individuals, fishes in pairs exhibit longer vigilance bouts, suggesting that the help provided to the partner is costly. In turn, fishes in pairs take more consecutive bites and penetrate deeper into crevices than solitary individuals, suggesting that the safety provided by a vigilant partner may outweigh initial costs by increasing foraging efficiency. Thus, the described system appears to meet all of the requirements for direct reciprocity. We argue that the nature of rabbitfish pairs provides favourable conditions for the establishment of direct reciprocity, as continuous interaction with the same partner, simultaneous needs, interdependence, and communication relax the cognitive demands of reciprocal cooperation.
Full Text Available This Collective Article presents information on 22 species belonging to 5 Phyla, arranged geographically from from west to east. The new records were found in 8 countries as follows: Spain: first record of the two scarcely known nemerteans Baseodiscus delineatus and Notospermus geniculatus in Formentera; Malta: second record of the alien fish Lagocephalus sceleratus; Italy: the alien polychaete Syllis pectinans and the isopod Paranthura japonica, as well as the cryptogenic opisthobranch Anteaeolidiella lurana, were found in the fouling assemblages along the docks of the port of Livorno. New decapod records are reported from Sicily (the alien Callinectes sapidus and the native Pachygrapsus maurus and Apulia (Percnon gibbosus and Procambarus clarkii; the lesser amberjack Seriola fasciata extended its geographical range to the Egadi Isands and Siganus luridus was documented for the first time along the Ionian coasts of Apulia and Calabria. Slovenia: the first record of the alien bivalve Brachidontes pharaonis is reported, together with a survey of up to date Adriatic records. Greece: the first record of the gastropod Rhinoclavis kochi is reported from Gavdos island. In addition, two records of endangered and rare cartilaginous fish were reported, namely, the shark Hexanchus griseus and the ray Leucoraja fullonica, as well as additional records of Siganus luridus for Lesvos and Malleus regula and Fulvia fragilis from Astypalaia. Turkey: the black wing flyingfish Hirundichthys rondeletii is reported for the very first time from the Black Sea. Egypt: the Indo-Pacific crab Halimede ochtodes is reported as established in Port Said. In addition, biometric parameters and meristic counts are reported for Anthias anthias in Damietta. Cyprus: the alien opisthobranch gastropod Bursatella leachii is reported for first time.
Full Text Available BACKGROUND: In order to understand feeding ecology and habitat use of coral reef fish, fatty acid composition was examined in five coral reef fishes, Thalassoma lunare, Lutjanus lutjanus, Abudefduf bengalensis, Scarus rivulatus and Scolopsis affinis collected in the Bidong Island of Malaysian South China Sea. RESULTS: Proportions of saturated fatty acids (SAFA ranged 57.2% 74.2%, with the highest proportions in fatty acids, the second highest was monounsaturated fatty acids (MUFA ranged from 21.4% to 39.0% and the proportion of polyunsaturated fatty acids (PUFA was the lowest ranged from 2.8% to 14.1%. Each fatty acid composition differed among fishes, suggesting diverse feeding ecology, habitat use and migration during the fishes' life history in the coral reef habitats. CONCLUSIONS: Diets of the coral fish species might vary among species in spite of that each species are living sympatrically. Differences in fatty acid profiles might not just be considered with respect to the diets, but might be based on the habitat and migration.
Arai, Takaomi; Amalina, Razikin; Bachok, Zainudin
In order to understand feeding ecology and habitat use of coral reef fish, fatty acid composition was examined in five coral reef fishes, Thalassoma lunare, Lutjanus lutjanus, Abudefduf bengalensis, Scarus rivulatus and Scolopsis affinis collected in the Bidong Island of Malaysian South China Sea. Proportions of saturated fatty acids (SAFA) ranged 57.2% 74.2%, with the highest proportions in fatty acids, the second highest was monounsaturated fatty acids (MUFA) ranged from 21.4% to 39.0% and the proportion of polyunsaturated fatty acids (PUFA) was the lowest ranged from 2.8% to 14.1%. Each fatty acid composition differed among fishes, suggesting diverse feeding ecology, habitat use and migration during the fishes' life history in the coral reef habitats. Diets of the coral fish species might vary among species in spite of that each species are living sympatrically. Differences in fatty acid profiles might not just be considered with respect to the diets, but might be based on the habitat and migration.
Chong-Seng, K. M.; Nash, K. L.; Bellwood, D. R.; Graham, N. A. J.
Macroalgal-feeding fishes are considered to be a key functional group on coral reefs due to their role in preventing phase shifts from coral to macroalgal dominance, and potentially reversing the shift should it occur. However, assessments of macroalgal herbivory using bioassay experiments are primarily from systems with relatively high coral cover. This raises the question of whether continued functionality can be ensured in degraded systems. It is clearly important to determine whether the species that remove macroalgae on coral-dominated reefs will still be present and performing significant algal removal on macroalgal-dominated reefs. We compared the identity and effectiveness of macroalgal-feeding fishes on reefs in two conditions post-disturbance—those regenerating with high live coral cover (20-46 %) and those degrading with high macroalgal cover (57-82 %). Using filmed Sargassum bioassays, we found significantly different Sargassum biomass loss between the two conditions; mean assay weight loss due to herbivory was 27.9 ± 4.9 % on coral-dominated reefs and 2.2 ± 1.1 % on reefs with high macroalgal cover. However, once standardised for the availability of macroalgae on the reefs, the rates of removal were similar between the two reef conditions (4.8 ± 4.1 g m-2 h-1 on coral-dominated and 5.3 ± 2.1 g m-2 h-1 on macroalgal-dominated reefs). Interestingly, the Sargassum-assay consumer assemblages differed between reef conditions; nominally grazing herbivores, Siganus puelloides and Chlorurus sordidus, and the browser , Siganus sutor, dominated feeding on high coral cover reefs, whereas browsing herbivores, Naso elegans, Naso unicornis, and Leptoscarus vaigiensis, prevailed on macroalgal-dominated reefs. It appeared that macroalgal density in the surrounding habitat had a strong influence on the species driving the process of macroalgal removal. This suggests that although the function of macroalgal removal may continue, the species responsible may change
Takeuchi, Yuki; Kabutomori, Ryo; Yamauchi, Chihiro; Miyagi, Hitomi; Takemura, Akihiro; Okano, Keiko; Okano, Toshiyuki
Goldlined spinefoot, Siganus guttatus, inhabits tropical and subtropical waters and synchronizes its spawning around the first quarter moon likely using an hourglass-like lunar timer. In previous studies, we have found that clock genes (Cryptochrome3 and Period1) could play the role of state variable in the diencephalon when determining the lunar phase for spawning. Here, we identified three Cry, two Per, two Clock, and two Bmal genes in S. guttatus and investigated their expression patterns in the diencephalon and pituitary gland. We further evaluated the effect on their expression patterns by daily interruptions of moonlight stimuli for 1 lunar cycle beginning at the new moon. It significantly modified the expression patterns in many of the examined clock(-related) genes including Cry3 in the diencephalon and/or pituitary gland. Acute interruptions of moonlight around the waxing gibbous moon upregulated nocturnal expressions of Cry1b and Cry2 in the diencephalon and pituitary gland, respectively, but did not affect expression levels of the other clock genes. These results highlighted the importance of repetitive moonlight illumination for stable or lunar-phase-specific daily expression of clock genes in the next lunar cycle that may be important for the lunar-phase-synchronized spawning on the next first quarter moon.
Fukushiro, Masato; Takeuchi, Takahiro; Takeuchi, Yuki; Hur, Sung-Pyo; Sugama, Nozomi; Takemura, Akihiro; Kubo, Yoko; Okano, Keiko; Okano, Toshiyuki
Lunar cycle-associated physiology has been found in a wide variety of organisms. Recent study has revealed that mRNA levels of Cryptochrome (Cry), one of the circadian clock genes, were significantly higher on a full moon night than on a new moon night in coral, implying the involvement of a photoreception system in the lunar-synchronized spawning. To better establish the generalities surrounding such a mechanism and explore the underlying molecular mechanism, we focused on the relationship between lunar phase, Cry gene expression, and the spawning behavior in a lunar-synchronized spawner, the goldlined spinefoot (Siganus guttatus), and we identified two kinds of Cry genes in this animal. Their mRNA levels showed lunar cycle-dependent expression in the medial part of the brain (mesencephalon and diencephalon) peaking at the first quarter moon. Since this lunar phase coincided with the reproductive phase of the goldlined spinefoot, Cry gene expression was considered a state variable in the lunar phase recognition system. Based on the expression profiles of SgCrys together with the moonlight's pattern of timing and duration during its nightly lunar cycle, we have further speculated on a model of lunar phase recognition for reproductive control in the goldlined spinefoot, which integrates both moonlight and circadian signals in a manner similar to photoperiodic response.
Madiyani, K. D. P.; Triastuti, J.; Pursetyo, K. T.
Teluk Wondama Regency is one of the areas in West Papua that is part of the Cendrawasih Bay National Park due to its potential of coral fishes. Until now, there is no thorough information that gives the potential diversities of coral fishes species can be found in the waters, and one of the attempts to find out is to carry out an inventory. Inventories were conducted from March to May 2016 in Rariei and Auri (Roon District), Numamuran (Duairi District), Nusrowi (Rumberpon District) and Waprak (Roswar District). The results of these inventories found 28 species of coral fishes in Rariei consisting of 8 genus (Balistapus, Synodus, Pentapodus, Thalassoma, Zebrasoma, Amblyglyphidodon, Chaetodon and Labroides) in Rariei, 11 genus (Abudefduf, Chaetodon, Amphiprion, Cheilinus, Dascyllus, Chromis, Parastromateus, Priacanthus, Epinephelus, Nemipterus and Lutjanus) in Namamuran, 11 genus in Nusrowi (Halichoeres, Pomacentrus, Dischistodus, Heniochus, Amblyglyphidodon, Arothron, Parupeneus, Lutjanus, Plectropomus, Epinephelus and Acanthurus), 4 genus in the waters of Waprak (Parupeneus, Pomacentrus, Chaetodon and Amblyglyphidodon) and 10 genus in Auri (Lutjanus, Pomacentrus, Amphiprion, Chaetodon, Chromis, Dascyllus, Zanclus, Halichoeres, Siganus and Amblyglyphidodon)
Kassem, Hamed H; Bowashi, Salem Mohamed
This study examined eight hundred ninety six marine fishes belonging to nine different fish species; Synodus saurus; Merluccius merluccius; Trachurus mediterraneus; Serranus cabrilla; Mullus surmuletus; Diplodus annularis; Spicara maena; Siganus rirulatus and Liza ramada. The fishes were bought from fish markets at five different sites on Libyan coast, from January to December 2013, for study the anisakids larvae among them. The results showed that 344/896 fishes (38.4%) were infected with Anisakids larvae. S. saurus was the highly infected (80.9%), followed by T mediterraneus (77.5%) but, S. cabrilla, S. maena, M merluccius, M surmuletus, and D. annularis were least anisakid infected showed rates of 58.2%, 53.8%, 43.7%, 36.7% & 3.6%, respectively. No parasites were in S. rirulatus and L, ramada. Ten species of Anisakids larvae was detected during the present study. Two Pseudoterranova sp. Larvae, two types of Anisakis larvae, Anisakis simplex larva and Anisakis sp. Larva, two types of Contracaecum sp. Larvae and four Hysterothylacium larvae. Females showed higher prevalence than males. The number of anisakid larvae varied according to body length and weight of infected fish, without significant difference between prevalence and seasons, but, a significant difference was between prevalence and regions.
Full Text Available White leg shrimp (Litopenaeus vannamei farming effluent contains pollutants that include high levels of organic matter (OM nutrients and growth-promoting substances. This study investigated the effects of varied concentrations of white leg shrimp (Litopenaeus vannamei farm wastewater 0, 50, 75 and 100%, on the survival rate (SR of three finfish species: tilapia (Oreochromis niloticus, grey mullet (Mugil cephalus and rabbit fish (Siganus guttatus as part of screening their potential in removing organic matter from the effluent of white leg shrimp farming. The different initial levels of shrimp wastewater from 50% to 100% had no significant effect on the survival rate of tilapia and mullet; but the survival rate of S. guttatus significantly decreased with increasing shrimp wastewater (P<0.05. The results showed that the removal of BOD, COD and TSS occurred in the range of 66-83, 68-81 and 30-54%; respectively and the removal efficiency of OM by mullet was higher than Tilapia in all treatments. The study also indicated that the reduction highest removal of BOD, COD and TSS was achieved being 83.1%, 80.7and 53,7% respectively, at the medium stocking density (25 fish/m2 of mullet.
Musilová, Zuzana; Rícan, Oldrich; Janko, Karel; Novák, Jindrich
We have conducted the first comprehensive molecular phylogeny of the tribe Cichlasomatini including all valid genera as well as important species of questionable generic status. To recover the relationships among cichlasomatine genera and to test their monophyly we analyzed sequences from two mitochondrial (16S rRNA, cytochrome b) and one nuclear marker (first intron of S7 ribosomal gene) totalling 2236 bp. Our data suggest that all genera except Aequidens are monophyletic, but we found important disagreements between the traditional morphological relationships and the phylogeny based on our molecular data. Our analyses support the following conclusions: (a) Aequidens sensu stricto is paraphyletic, including also Cichlasoma (CA clade); (b) Krobia is not closely related to Bujurquina and includes also the Guyanan Aequidens species A. potaroensis and probably A. paloemeuensis (KA clade). (c) Bujurquina and Tahuantinsuyoa are sister groups, closely related to an undescribed genus formed by the 'Aequidens'pulcher-'Aequidens'rivulatus groups (BTA clade). (d) Nannacara (plus Ivanacara) and Cleithracara are found as sister groups (NIC clade). Acaronia is most probably the sister group of the BTA clade, and Laetacara may be the sister group of this clade. Estimation of divergence times suggests that the divergence of Cichlasomatini started around 44Mya with the vicariance between coastal rivers of the Guyanas (KA and NIC clades) and remaining cis-andean South America, followed by evolution of the Acaronia-Laetacara-BTA clade in Western Amazon, and the CA clade in the Eastern Amazon. Vicariant divergence has played importantly in evolution of cichlasomatine genera, with dispersal limited to later range extension of species within genera.
Jiddawi, Narriman S; Ohman, Marcus C
Fishery resources are a vital source of food and make valuable economic contributions to the local communities involved in fishery activities along the 850 km stretch of the Tanzania coastline and numerous islands. Small-scale artisanal fishery accounts for the majority of fish catch produced by more than 43 000 fishermen in the country, mainly operating in shallow waters within the continental shelf, using traditional fishing vessels including small boats, dhows, canoes, outrigger canoes and dinghys. Various fishing techniques are applied using uncomplicated passive fishing gears such as basket traps, fence traps, nets as well as different hook and line techniques. Species composition and size of the fish varies with gear type and location. More than 500 species of fish are utilized for food with reef fishes being the most important category including emperors, snappers, sweetlips, parrotfish, surgeonfish, rabbitfish, groupers and goatfish. Most of the fish products are used for subsistence purposes. However, some are exported. Destructive fishing methods such as drag nets and dynamite fishing pose a serious problem as they destroy important habitats for fish and other organisms, and there is a long-term trend of overharvested fishery resources. However, fishing pressure varies within the country as fishery resources are utilized in a sustainable manner in some areas. For this report more than 340 references about Tanzanian fishery and fish ecology were covered. There are many gaps in terms of information needed for successful fishery management regarding both basic and applied research. Most research results have been presented as grey literature (57%) with limited distribution; only one-fifth were scientific publications in international journals.
Full Text Available Keberadaan ikan karang merupakan salah satu bioindikator terhadap kondisi terumbu karang yang baik. Penelitian ikan karang di perairan Kendari bertujuan untuk mengetahui komposisi jenis, kelimpahan, sebaran, dan struktur komunitas ikan karang di perairan tersebut. Pengumpulan data dilakukan bulan Juli 2011 pada lima lokasi di bagian utara dan selatan Kendari. Data dihimpun dengan menggunakan teknik Underwater Visual Census (UVC dan metode transek (Line Intersept Transect, LIT dengan peralatan SCUBA. Total jenis ikan karang terkumpul sebanyak 111 jenis yang mewakili 24 famili, terdiri dari 31 jenis ikan target (ikan konsumsi, 17 jenis ikan indikator (indicator species, dan kelompok major 63 jenis. Kelornpok ikan pangan (target yang dominan; Caesio cuning, Siganus vulpinus dan Ctenochaetus striatus. Jenis yang paling dominan dari ikan indikator adalah Chaetodon octofasciatus. Sedangkan kelompok lainnya (major yang dominan adalah Pomacentrus smithii, Chrysiptera rollandi, Chrysiptera springeri, dan Pomacentrus alexanderae. Nilai Indeks keanekaragaman berkisar 1,36– 3,23. Indeks dominasi Margalef (d berkisar 4,74–8,66. Indeks kemerataan Pielou (J’=H’/logeS diperololeh pada kisaran 0,38–0,81 . Hasil analisis kluster pada matrik kesamaan Bray-Curtis 37 % diperoleh dendrograrn yang menunjukkan dua pengelompokan stasiun. Berdasarkan ordinasi sampel dengan MDS diperoleh dari kesamaan (stress= 0 dengan jelas menunjukkan dua komunitas yang berbeda. Hasil penelitian ini diharapkan dapat menjadi masukan sebagai data dasar untuk pengelolaan daerah pesisir bagi pemerintahan daerah (PEMDA. Kata kunci: ikan karang, struktur komunitas, indeks ekologi, perairan Kendari. Coral reef Fishes is one of bio-indicators for good condition coral reef ecosystem. A study on coral reef fishes in the Kendari waters was aimed to find out species composition, abundance, distribution and community structure of coral reef fishes in that area. The study was conducted in
Lalu Samsul Rizal
Full Text Available The aims of the research was to determine the perceptions of stakeholders (Community, Government and Employers, to know the potential of mangrove species and determine the impact of mangrove degradation on fish and non-fish biota, at Labuhan Sangoro coastal village. This study was conducted for three months from April to June 2012. Data were analyzed descriptively using a Likert scale for the perception of stakeholders. Potential mangrove species was examined using transects and to determine the impact of mangrove degradation on species diversity of aquatic fauna associated with mangrove were obtained by observation of nonparticipant method. The results showed that perceptions of stakeholders towards preservation and conservation of mangrove land, the 87% strongly agreed, 66% agreed and 22% disagreed, government and employers 86% strongly agree, 78% agree and disagree 3%, but not yet to the application phase. The potential of mangrove type in the coastal village of Labuan Sangoro at Station 1, 2, 3, and 4 by R. mucronata and R. stylosa, Transect I dominated by Rhizophora mucronata, R. stylosa, R. apiculata, Sonneratia alba, Lumnitzera racemosa and Ceriops tagal, transect II by Avicennia marina, R. mucronata and R. stylosa, Transect III by A. marina and R. mucronata and transect IV by R. mucronata and R. stylosa. Fish eatch on the condition of low and high degradation condition, the dominant fish species caught is Beronang (Siganus sp, non-fish species dominated by Crab (Scylla serrata. The number of catches in the low mangrove land degradation conditions wais 2,609 species of fish and non-fish tail 4678, on the high mangrove degradation conditions, the fish catch was 1,090 and non-fish was 1,114. The diversity, uniformity and the dominance of species, classified in the category of low and moderate levels.
Ikegami, Taro; Takeuchi, Yuki; Hur, Sung-Pyo; Takemura, Akihiro
The waxing and waning cycle of the moon is repeated at approximately 1-month intervals, and concomitant changes occur in the levels of moonlight and cueing signals detected by organisms on the earth. In the goldlined spinefoot Siganus guttatus, a spawner lunar-synchronized around the first quarter moon, periodic changes in moonlight are used to cue gonadal development and gamete release. Rearing of mature fish under artificial constant full moon and new moon conditions during the spawning season leads to disruption or delay of synchronous spawning around the predicted moon phase. Melatonin, an endogenous transducer of the environmental light/dark cycle, increases in the blood and in the pineal gland around the new moon period and decreases around the full moon period. In synchrony with melatonin fluctuation, melatonin receptor(s) mRNA abundance is higher during the new moon period than during the full moon. The melatonin/melatonin receptor system is likely affected by moonlight. Measurements of the expression patterns of clock genes in neural tissues demonstrate that Cryptochrome (Cry1 and Cry3) and Period (Per2) fluctuate with lunar periodicity, the former peaking in the medial part of the brain around the first quarter moon period, and the latter peaking in the pineal gland around the full moon. Some clock genes may respond to periodic changes in moon phase and appear to be involved in the generation of lunar-related rhythmicity in lunar spawners. Thus, some fish use moonlight-related periodicities as reliable information for synchronizing the timing of reproductive events. Copyright © 2013 Elsevier B.V. All rights reserved.
Hicks, Christina C; McClanahan, Timothy R
Effective management is necessary if small-scale fisheries, such as those found in mixed habitats including seagrass and coral reefs, are to continue providing food for many of the poorest communities of the world. Gear-based management, although under represented and under studied, has the potential to be adaptive, address multiple objectives, and be crafted to the socio-economic setting. Management effectiveness in seagrass and coral reef fisheries has generally been evaluated at the scale of the fish community. However, community level indicators can mask species-specific declines that provide significant portions of the fisheries yields and income. Using a unique dataset, containing ten years of species level length frequency catch data from a multi-gear, multi-species seagrass and coral reef fishery in Kenya, we evaluate species specific fishery statuses, compare gear use to gear regulations and estimate the potential needs for further gear restrictions. Despite the high diversity of the fishery, fifteen species represented over 90% of the catch, and only three species represented 60% of the catch. The three most abundant species in the catch, Lethrinus lentjan (Lacepède), Siganus sutor (Valenciennes) and Leptoscarus vaigiensis (Quoy & Gaimard) all showed evidence of growth overfishing. Lethrinus lentjan, with an exploitation rate of 0.82, also shows evidence of recruitment overfishing. Current legal but weakly enforced gear restrictions are capable of protecting a significant portion of the catch up to maturity but optimization of yield will require that the current mesh size be increased from 6.3 to 8.8 and 9.2 cm to increase yields of L. lentjan and S. sutor, respectively. Given the difficulties of enforcing mesh size, we recommend that the economic benefits of these larger mesh sizes be communicated and enforced through co-management. This abstract is also available in Kiswahili (Abstract S1).
Christina C Hicks
Full Text Available Effective management is necessary if small-scale fisheries, such as those found in mixed habitats including seagrass and coral reefs, are to continue providing food for many of the poorest communities of the world. Gear-based management, although under represented and under studied, has the potential to be adaptive, address multiple objectives, and be crafted to the socio-economic setting. Management effectiveness in seagrass and coral reef fisheries has generally been evaluated at the scale of the fish community. However, community level indicators can mask species-specific declines that provide significant portions of the fisheries yields and income. Using a unique dataset, containing ten years of species level length frequency catch data from a multi-gear, multi-species seagrass and coral reef fishery in Kenya, we evaluate species specific fishery statuses, compare gear use to gear regulations and estimate the potential needs for further gear restrictions. Despite the high diversity of the fishery, fifteen species represented over 90% of the catch, and only three species represented 60% of the catch. The three most abundant species in the catch, Lethrinus lentjan (Lacepède, Siganus sutor (Valenciennes and Leptoscarus vaigiensis (Quoy & Gaimard all showed evidence of growth overfishing. Lethrinus lentjan, with an exploitation rate of 0.82, also shows evidence of recruitment overfishing. Current legal but weakly enforced gear restrictions are capable of protecting a significant portion of the catch up to maturity but optimization of yield will require that the current mesh size be increased from 6.3 to 8.8 and 9.2 cm to increase yields of L. lentjan and S. sutor, respectively. Given the difficulties of enforcing mesh size, we recommend that the economic benefits of these larger mesh sizes be communicated and enforced through co-management. This abstract is also available in Kiswahili (Abstract S1.
Full Text Available Since 2010, a bottom-up initiative has been launched in Santorini Island (Aegean Sea, Eastern Mediterranean for the establishment of the first fully-protected marine protected area in the Cyclades, aiming at improving fisheries and enhancing responsible recreational uses at sea. Following discussions with local small-scale fishers and divers, two sites along the southern and southeastern coasts of the island were suggested as suitable to this end. In 2012, a baseline study was conducted at these areas to assess their state and provide an ecological snapshot that would enable sound designation and monitoring. Several ad hoc indices and metrics were applied, taking into account structural and functional features of the upper infralittoral algae and Posidonia oceanica beds. An integrated assessment of the infralittoral fish assemblages and their associated benthic communities was also performed. Our most important findings were: (i the low total fish biomass and the absence of adult top predators, indicating overfishing; (ii the overgrazing effects of the overabundant alien herbivore spinefoot fishes (Siganus spp., as reflected by the abnormal structure of the algal communities; (iii the scarcity of signs of pollution or other direct anthropogenic pressures, as indicated by the good environmental status of the P. oceanica meadows and the upper infralittoral vegetation; and (iv the presence of a rich diversity of species and habitats, especially along the Akrotiri Peninsula and the wider volcanic Caldera. These findings provide useful insights on strengths and weaknesses of the study area and are discussed together with their implications for protection and management.
Toda, Riko; Okano, Keiko; Takeuchi, Yuki; Yamauchi, Chihiro; Fukushiro, Masato; Takemura, Akihiro; Okano, Toshiyuki
Lunar cycle-associated physiology has been found in a wide variety of organisms. Studies suggest the presence of a circalunar clock in some animals, but the location of the lunar clock is unclear. We previously found lunar-associated expression of transcripts for Cryptochrome3 gene (SgCry3) in the brain of a lunar phase-responsive fish, the Goldlined spinefoot (Siganus guttatus). Then we proposed a photoperiodic model for the lunar phase response, in which SgCry3 might function as a phase-specific light response gene and/or an oscillatory factor in unidentified circalunar clock. In this study, we have developed an anti-SgCRY3 antibody to identify SgCRY3-immunoreactive cells in the brain. We found immunoreactions in the subependymal cells located in the mediobasal region of the diencephalon, a crucial site for photoperiodic seasonal responses in birds. For further assessment of the lunar-responding mechanism and the circalunar clock, we investigated mRNA levels of Cry3 as well as those of the other clock(-related) genes, Period (Per2 and Per4), in S. guttatus reared under nocturnal moonlight interruption or natural conditions. Not only SgCry3 but SgPer4 mRNA levels showed lunar phase-dependent variations in the diencephalon without depending on light condition during the night. These results suggest that the expressions of SgCry3 and SgPer4 are not directly regulated by moonlight stimulation but endogenously mediated in the brain, and implicate that circadian clock(-related) genes may be involved in the circalunar clock locating within the mediobasal region of the diencephalon.
Rosli, M. N. R.; Samat, S. B.; Yasir, M. S.
Bioaccumulation of toxic metals in fish causes serious threats to the human when they are consumed. Thus, the detection of toxic element concentration levels in fish is important. The accumulation of four heavy metal concentration of Cd, Cu, Mn and Zn in fish was determined. Five fish species namely Epinephelus lanceolatus, Rastrelliger, Megalaspis cordyla, Bramidae and Siganus canaliculatus were collected from the coastal waters of Terengganu, Malaysia. The analysis was done using inductive coupled plasma-mass spectrometer (ICP-MS) technique. The accumulation of the four heavy metals in muscle tissues of the fish are lower compared to liver and gill tissues. Cd concentration was higher in liver tissues except in Megalaspis cordyla. Meanwhile Cu concentration was higher in liver for all selected fishes. Mn concentration was higher in gill tissues of all fish studied while Zn concentration was higher in gill tissues except in Epinephelus lanceolatus and Rastrelliger. The highest average level of heavy metal recorded in fish is Zn (11.05 × 10-2 ± 1.44 × 10-2 mg kg-1) followed by Mn (1.81 × 10-2 ± 0.58 × 10-2 mg kg-1), Cu (0.70 × 10-2 ± 0.10 × 10-2 mg kg-1) and Cd (0.52×10-2 ± 0.27 × 10-2 mg kg-1). The metal concentration found in this study was lower than the national and international Recommended Dietary Allowance (RDA) for human consumption. Long term monitoring system of metal bioaccumulation in fishes need to be done to provide useful information for the assessment of the potential health risks of metals in Malaysia.
Full Text Available An updated review of marine alien species and other ‘newcomers’ recorded from the Maltese Islands is presented on account of new records and amendments to a previous review in 2007. Species were classified according to their establishment status (‘Questionable’, ‘Casual’, ‘Established’, ‘Invasive’ and origin (‘Alien’, ‘Range expansion’, ‘Cryptogenic’. A total of 31 species were added to the inventory, while 6 species have been removed, bringing the total number of species to 73. Of these, 66 are considered to be aliens (or putative aliens but with uncertain origin with the remaining 7 resulting from range expansion. Six records are considered to be questionable and hence unverified. For verified records, the dominant taxonomic groups are Mollusca (represented by 21 species and Actinopterygii (15 species, followed by Crustacea (8 species and Rhodophyta (7 species. Eight of these species (aliens: Caulerpa cylindracea, Lophocladia lallemandi, Womersleyella setacea, Brachidontes pharaonis, Percnon gibbesi, Fistularia commersonii, Siganus luridus; range extender: Sphoeroides pachygaster are considered to be invasive. The introduction pathway for 30 species is unknown. Amongst the alien species, ‘Shipping’ is the most common introduction pathway, followed by ‘Secondary dispersal’ from elsewhere in the Mediterranean Sea. An increasing trend in the number of alien marine species reported from the Maltese Islands is evident, with a peak of 22 species recorded during the last decade (2001–2010. A discussion on the rationale for including range-expanding species in national inventories of recent arrivals, and in the analysis of trends in records from the Maltese Islands, is included. In particular, the general warming trend of Mediterranean surface waters appears to be facilitating the westward spread of thermophilic alien species from the Eastern to the Central Mediterranean, and the eastward range expansion of
Full Text Available Lunar cycle-associated physiology has been found in a wide variety of organisms. Studies suggest the presence of a circalunar clock in some animals, but the location of the lunar clock is unclear. We previously found lunar-associated expression of transcripts for Cryptochrome3 gene (SgCry3 in the brain of a lunar phase-responsive fish, the Goldlined spinefoot (Siganus guttatus. Then we proposed a photoperiodic model for the lunar phase response, in which SgCry3 might function as a phase-specific light response gene and/or an oscillatory factor in unidentified circalunar clock. In this study, we have developed an anti-SgCRY3 antibody to identify SgCRY3-immunoreactive cells in the brain. We found immunoreactions in the subependymal cells located in the mediobasal region of the diencephalon, a crucial site for photoperiodic seasonal responses in birds. For further assessment of the lunar-responding mechanism and the circalunar clock, we investigated mRNA levels of Cry3 as well as those of the other clock(-related genes, Period (Per2 and Per4, in S. guttatus reared under nocturnal moonlight interruption or natural conditions. Not only SgCry3 but SgPer4 mRNA levels showed lunar phase-dependent variations in the diencephalon without depending on light condition during the night. These results suggest that the expressions of SgCry3 and SgPer4 are not directly regulated by moonlight stimulation but endogenously mediated in the brain, and implicate that circadian clock(-related genes may be involved in the circalunar clock locating within the mediobasal region of the diencephalon.
Esteban, N; Unsworth, R K F; Gourlay, J B Q; Hays, G C
Our understanding of global seagrass ecosystems comes largely from regions characterized by human impacts with limited data from habitats defined as notionally pristine. Seagrass assessments also largely focus on shallow-water coastal habitats with comparatively few studies on offshore deep-water seagrasses. We satellite tracked green turtles (Chelonia mydas), which are known to forage on seagrasses, to a remote, pristine deep-water environment in the Western Indian Ocean, the Great Chagos Bank, which lies in the heart of one of the world's largest marine protected areas (MPAs). Subsequently we used in-situ SCUBA and baited video surveys to survey the day-time sites occupied by turtles and discovered extensive monospecific seagrass meadows of Thalassodendron ciliatum. At three sites that extended over 128 km, mean seagrass cover was 74% (mean range 67-88% across the 3 sites at depths to 29 m. The mean species richness of fish in seagrass meadows was 11 species per site (mean range 8-14 across the 3 sites). High fish abundance (e.g. Siganus sutor: mean MaxN.site -1 = 38.0, SD = 53.7, n = 5) and large predatory shark (Carcharhinus amblyrhynchos) (mean MaxN.site -1 = 1.5, SD = 0.4, n = 5) were recorded at all sites. Such observations of seagrass meadows with large top predators, are limited in the literature. Given that the Great Chagos Bank extends over approximately 12,500 km 2 and many other large deep submerged banks exist across the world's oceans, our results suggest that deep-water seagrass may be far more abundant than previously suspected. Copyright © 2018 The Author(s). Published by Elsevier Ltd.. All rights reserved.
Al-Arrayedu, F. H.; Al Maskati, H. A.; Abdullah, F. J.
This study was performed to determine the content of n3- polyunsaturated fatty acids in 10 fish species that are commonly consumed in Bahrain in addition to the main commercial shrimp species. White sardinella, which is a plankton feeder, had the highest content of n3- polyunsaturated fatty acids. It had the highest value of eicosapentaenoic acid (146.5 ± 20 mg 100 g-1) and linolenic acid (98.9±f 100 g-1) and the second highest value of docosahexaenoic acid at (133.7 ± 22 mg 100 g-1). Spanish mackerel which feeds mainly on sardinella was second with eicosapentaenoc acid at 55 ± 5.4 mg 100 g-1, docosahexaenoic acid at 161 ± 19.8 mg 100 g-1, linolenic acid at 16.4 mg 100 g-1 and docosapentaenoic acid at 25 ± 1.9 mg 100 g-1. Rabbitfish, the most popular edible fish in Bahrain which feeds mainly on benthic algae had the third highest content of n3- polyunsaturated fatty acids with eicosapentaenoic acid at 37.5 ± 3.9 mg 100 g-1, docosahexaenoic acid at 76 ± 6.7 mg 100 g-1, and docosapentaenoic acid at 85.8 ± 10 mg 100 g-1. The other fish and crustacean species studied were Arabian carpet shark, doublebar bream, grouper, gray grunt, golden travally, keeled mullet, spangled emperor and shrimp. The study explores the transfer of n3- polyunsaturated fatty acids through the food webs of the examined fish. It is apparent, generally, that plankton feeders displayed the highest content of n3- polyunsaturated fatty acids followed by seaweed and algae grazers, with benthic carnivores feeding on invertebrates displaying the poorest content. The values reported here, however, are much lower than those reported for fish available in American markets and in Mediterranean fish. Warm water temperature and high salinity which lead to lowering of the density of phytoplankton and phytoplankton content of n3- polyunsaturated fatty acids are suggested as the reason for the observed low values of n3- polyunsaturated fatty acids in Bahrain fish.
Brandl, Simon J; Bellwood, David R
Detailed knowledge of a species' functional niche is crucial for the study of ecological communities and processes. The extent of niche overlap, functional redundancy and functional complementarity is of particular importance if we are to understand ecosystem processes and their vulnerability to disturbances. Coral reefs are among the most threatened marine systems, and anthropogenic activity is changing the functional composition of reefs. The loss of herbivorous fishes is particularly concerning as the removal of algae is crucial for the growth and survival of corals. Yet, the foraging patterns of the various herbivorous fish species are poorly understood. Using a multidimensional framework, we present novel individual-based analyses of species' realized functional niches, which we apply to a herbivorous coral reef fish community. In calculating niche volumes for 21 species, based on their microhabitat utilization patterns during foraging, and computing functional overlaps, we provide a measurement of functional redundancy or complementarity. Complementarity is the inverse of redundancy and is defined as less than 50% overlap in niche volumes. The analyses reveal extensive complementarity with an average functional overlap of just 15.2%. Furthermore, the analyses divide herbivorous reef fishes into two broad groups. The first group (predominantly surgeonfishes and parrotfishes) comprises species feeding on exposed surfaces and predominantly open reef matrix or sandy substrata, resulting in small niche volumes and extensive complementarity. In contrast, the second group consists of species (predominantly rabbitfishes) that feed over a wider range of microhabitats, penetrating the reef matrix to exploit concealed surfaces of various substratum types. These species show high variation among individuals, leading to large niche volumes, more overlap and less complementarity. These results may have crucial consequences for our understanding of herbivorous processes on