Marine Fish Diversity Research Articles

Severely depleted genetic diversity and population structure of a large predatory marine fish (Lates japonicus) endemic to Japan

Marine fish generally show higher genetic diversity and shallower population structure than freshwater fish, but data for rare species are lacking. A latid fish, akame (Lates japonicus), is a rare, large predatory fish endemic to Japan, occurring mainly in the estuaries and coastal waters of Kochi and Miyazaki prefectures. Among species of Lates, akame is the only one adapted to temperate waters, while the others are distributed in tropical waters. Despite conservation concerns for this species, almost nothing is known about its population genetic characteristics. We used amplified fragment length polymorphism (AFLP) and mitochondrial DNA (mtDNA) markers to describe the genetic variation and its partitioning among juvenile samples collected from multiple localities and over different years. Twenty-four primer combinations detected a total of 522 AFLP loci, only 40 (7.7 %) of which were polymorphic. Sequence analysis of the entire mtDNA control region identified only five haplotypes defined by four variable sites. The level of genetic diversity revealed by both genetic markers was unusually low compared to other marine fish and comparable to levels observed for some endangered freshwater fish exhibiting some of the lowest levels of genetic diversity among vertebrate populations. Analysis of molecular variance for the AFLP data indicated a weak but significant population structure (F CT = 0.07, P < 0.001) between the Kochi and Miyazaki regions. Our results highlight the need for in situ conservation efforts for akame across its entire distribution range and throughout its entire life cycle to minimize extinction risks associated with environmental and demographic stochasticity.

Marine fish diversity and habitat use along the western coast of the Black Sea

Event Abstract Back to Event Marine fish diversity and habitat use along the western coast of the Black Sea Viorel D. Gavril1, 2, 3* 1 Institutu of Biology, Bucharest, Romania 2 Oceanographic Research and Marine Environment Protection Society Oceanic-Club, Romania 3 University of Bucharest, Faculty of Geography, Romania Over the years the conditions of the Black Sea marine habitats have been modified due to anthropogenic impacts and climate change, and it is likely that the diversity of fish fauna changed as a result. This study provides new data regarding marine fish population diversity and habitat use along the western coast of the Black Sea. I recorded fish species and habitat data between 2011 and 2014 in two locations: Constanta, Romania and Shabla-Tyulenovo coast, Bulgaria, using fishing (only in Romania) and scuba visual transects (Romania and Bulgaria). During this period, we identified a number of 45 fish species, belonging to 14 orders and 30 families. Observations made while scuba diving were of great importance for this study, as 47% of the species were identified using this method. These species include Sciaena umbra, Salaria pavo, Coryphoblennius galerita, Callionymus pusillus, Aphia minuta, Ophidion rochei, Diplodus annularis, and Chelidonichthys lucerna. Five broad types of habitats were delimited for the species identified: pelagic, sandy bottoms, rocky bottoms, rocky habitats with Cystoseira sp. and man-made structures like breakwaters. Vertically, the delimitation was made above and below the 10 meter line based on due to the differences in temperature, light penetration and surface wave interference. I identified 34 species of fish in the Shabla-Tyulenovo area and 39 species in the Constanta area, of which 19 species preferred sandy bottoms, 21 rocky bottoms, 16 rocky habitats with Cystoseira sp., 19 man-made structures and 9 were pelagic. For 7 species habitat preferences could not be determined as a result of capture only by fishing. In conclusion, the scuba visual transects along with fishing methods provide a relevant image to the current state of the fish diversity along the western coast of the Black Sea. Acknowledgements I would like to acknowledge O.R.M.E.P.S. Oceanic-Club for supporting the costs for the participation to the XV European Congress of Ichthyology and providing logistic help during field work. This study was partially supported by the Romanian Academy, Institute of Biology, Bucharest Project 4 (RO1567-IBB04/2015). Keywords: Fishes, habitat use, Black Sea, Romania, SCUBA diving Conference: XV European Congress of Ichthyology, Porto, Portugal, 7 Sep - 11 Sep, 2015. Presentation Type: Oral Presentation Topic: Ecology, Conservation and Invasive Species Citation: Gavril VD (2015). Marine fish diversity and habitat use along the western coast of the Black Sea. Front. Mar. Sci. Conference Abstract: XV European Congress of Ichthyology. doi: 10.3389/conf.FMARS.2015.03.00177 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 30 Nov 2015; Published Online: 01 Dec 2015. * Correspondence: Mr. Viorel D Gavril, Institutu of Biology, Bucharest, Bucharest, Romania, viorel.gavril26@gmail.com Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract Supplemental Data The Authors in Frontiers Viorel D Gavril Google Viorel D Gavril Google Scholar Viorel D Gavril PubMed Viorel D Gavril Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Marine and estuarine fish diversity in the inner Gulf of Nicoya, Pacific coast of Costa Rica, Central America

A checklist of the marine and estuarine fishes of the inner part of the Gulf of Nicoya, Pacific coast of Costa Rica, Central America, was compiled by examining a museum fish collection, resulting in 72 families and 274 species. Of these species, 127 (46.4%) were marine species and 147 (53.6%) were estuarine-associated species. In terms of their life history and considering the habitat type classification, 188 (almost 70% of the total) were categorized as species inhabiting soft-bottom habitats, reflecting the large estuarine environment and rich fish diversity of the Gulf despite its relatively small area in the tropical Eastern Pacific region. Furthermore, the list contains 13 threatened species of IUCN Red List, which need further research to understand their abundance and their exposure to habitat loss in the Gulf. Further detailed studies on its fish fauna and habitat are needed to better understand and conserve biodiversity within the whole Gulf.

Long-term variation in the ichthyofauna of Flamengo Cove, Ubatuba, São Paulo

The Brazilian coastline extends along more than 8,000 km covering approximately 38 degrees of latitudinal range through tropical, subtropical and warm-temperate climates and includes a wide variety of marine environments such as sandy beaches, estuaries, rocky shores and reefs. This heterogeneity of habitats is reflected in the diversity of marine fishes found in Brazilian waters which sums approximately 1,300 known species. Approximately 600 marine species are estimated to occur off the coast of Sao Paulo State. Long-term studies are useful to better access variation in the fish community due to slow processes, rare or episodic events, and highly variable or complex phenomena. Our survey of the fishes of Flamengo Cove, Ubatuba, Sao Paulo, included two periods set apart 10 years from each other (1990 and 2000), in which the soft-bottom ichthyofauna was sampled with an otter trawl in autumn and spring. We sampled 782 individuals weighing 18,113.3 g representing 37 species and 19 families. Five species are considered as threatened in the State of Sao Paulo, three of them under threat of overexplotation in the federal context, and two are included in the IUCN’s Red List. The dominant family was the Sciaenidae, with eight species from both periods. We evidenced a significant variation in the structure of the ichthyofauna between 1990 and 2000, and between autumn and spring, although the number of species did not change. The most important species in terms of number of individuals and biomass were Ctenosciaena gracilicirrhus and Paralonchurus brasiliensis, respectively. Data on both of these species indicate that recruitment occurred during spring, when more and smaller individuals were sampled. More long-time studies such as this are encouraged to better understand differences in the variation of the structure of fish communities in Brazilian marine waters.

Multilocus phylogeography of the sea snake Hydrophis curtus reveals historical vicariance and cryptic lineage diversity

The Indo‐Australian archipelago (IAA) supports the world's highest diversity of marine fish, invertebrates and reptiles. Many of the marine fish and invertebrates show congruent phylogeographic patterns, supporting a view that the region's complex geo‐climatic history has played an important role in generating its exceptional biodiversity. Here, we examine population genetic structure of the viviparous sea snake, Hydrophis curtus, to assess how past and present barriers to gene flow in the IAA have contributed to genetic and species diversity in a fully marine reptile. Mitochondrial and anonymous nuclear sequences and ten microsatellite loci were used to identify patterns of historical genetic structure and population expansion, reconstruct dated genealogies and assess levels of recent gene flow. These markers revealed strong concordant geographic structure within H. curtus with a prominent genetic break between populations broadly distributed in the Indian Ocean and the West Pacific. These populations were estimated to have diverged in the late Pliocene or early Pleistocene, and microsatellite admixture analyses suggested limited recent gene flow between them despite the current lack of barriers to dispersal, indicating possible cryptic species. Subsequent divergence in the mid–late Pleistocene was detected within the West Pacific clade among the populations in the Phuket‐Thailand region, South‐East Asia and Australia, and two of these populations also showed genetic signals of recent range expansions. Our results show that climatic fluctuations during the Plio‐Pleistocene generated high levels of cryptic genetic diversity in H. curtus, and add to similar findings for diverse other marine groups in the IAA.

Phylogeography of Blacktip Grouper, Epinephelus fasciatus (Perciformes: Serranidae), and influence of the Kuroshio Current on cryptic lineages and genetic population structure

To investigate the influence of the Kuroshio Current on the high diversity of marine fishes in Japanese waters, the intraspecific phylogeographic structure of Blacktip Grouper, Epinephelus fasciatus, was determined. The genetic analysis of E. fasciatus indicated three intraspecific mtDNA lineages representing different evolutionary histories: the first lineage differentiated in Japanese waters during a long period of fluctuations of the ancient Kuroshio Current, the second lineage, widely distributed in the tropical western Pacific, was transported to Japanese waters by the Kuroshio Current and the third lineage was distributed primarily around the Ogasawara (Bonin) Islands. Present-day sympatric distributions of the three lineages, characterized by different ratios of such individuals at each geographic site, indicated a complex genetic pattern that was classified into three demographic groups, the dispersal and gene flows of which were strongly influenced by the Kuroshio Current and factors such as countercurrent and island arc. Genetic breaks in E. fasciatus populations were congruent with other fish faunal boundaries in Japanese waters.

A spatial approach to matching marine fish diversity and abundance with habitat features

Current issues in marine resource management have in common a geospatial component and a need to integrate both biotic and abiotic data from various sources. We propose a practical approach to address these issues looking at the American plaice (Hippoglossoides platessoides) and the demersal fish fauna in the Gulf of St. Lawrence (Canada). Central to our approach was the use of a common spatial grid and three different methods to match biotic and abiotic features at a broad regional scale, (1) matching plaice distribution with habitat categories determined a priori on the basis of abiotic features (cluster analysis), (2) habitat categories determined taking into consideration both plaice density and abiotic features (simple regression tree), and (3) habitat categories determined taking into consideration demersal fish species density (70 fish species) and abiotic features (multivariate regression tree, MRT). Hot spots and cold spots of plaice abundance in summer were described and matched with specific habitats. The spatial distribution of habitats was similar whether biotic variables were used in the classification or not. The MRT, however, identified 56 different fish species in the plaice habitat (median species richness by 100 km2 cell = 12), pointing to potential interactions with other fish species.

Comparing diversity data collected using a protocol designed for volunteers with results from a professional alternative

Summary In light of the continuing biodiversity crisis, the need for high‐resolution, broad‐scale ecological data is particularly acute. The expansive scale of volunteer data collection programmes provides an opportunity to address this challenge, however, protocols used to collect such data are typically less standardized than those used by professional scientists. Although previous studies have established that different protocols can lead to different results, it remains unclear how relevant these differences are to specific study goals, such as biodiversity assessment. This study uses both null model and Bayesian occupancy approaches to examine the capacity of a widely used volunteer survey protocol, the roving diver transect, to detect patterns of marine fish diversity. Richness estimates are compared with those obtained using the conventional belt transects favoured in many peer reviewed studies, examining the power of both protocols to detect statistically significant differences between survey sites and quantifying differences in detectability. Pairwise site comparisons of α‐diversity (i.e. within site diversity) were consistent between protocols, particularly for species totals. The roving diver transect protocol detected a substantially larger number of species than the belt transect protocol, due to notably higher detectability, even after controlling for confounding factors. Both protocols detected the same species pool, although the species richness among observations was higher for the belt protocol at certain sites. The significance of pairwise site β‐diversity (i.e. differentiation between sites) comparisons differed between the protocols and care should be exercised, when using either protocol, when studying variation in species composition. These results provide vital information for managers and researchers considering the use of volunteer data or protocols for the purpose of biodiversity assessment in aquatic systems, helping to quantify the value of thousands of existing survey records. The larger number of species detected by the volunteer protocol suggests this protocol may be advantageous with regards to the completion of taxonomic lists.

Rocky reef fish assemblages at six Mediterranean marine protected areas: broad-scale patterns in assemblage structure, species richness and composition

Fish assemblages inhabiting shallow rocky reefs at six Italian marine protected areas (MPAs) were investigated to assess broad-scale patterns in assemblage structure, species richness and composition, and to evaluate the presence of a latitudinal gradient in the distribution pattern of a thermophilic fish, the ornate wrasse Thalassoma pavo. Fish abundance was estimated by visual censuses carried out within the integral reserve zones, within the 1--7 m depth range and during four sampling periods. Multivariate analyses revealed significant differences in the assemblage structure among MPAs, although patterns of variation changed considerably from time to time and they were not consistent with latitudinal or longitudinal gradient. Fish assemblages of Miramare (northern Adriatic) and those of the other MPAs clearly separated into two groups. Multivariate differences among MPAs mainly relied upon some relatively common species (e.g. Diplodus puntazzo and Muraena helena). Substantial contribution to these differences was also accounted for by T. pavo. Significant differences among MPAs were detected also in species richness and total density of fish, although the effect of MPA on species richness varied significantly from time to time. Both species richness and total density of fish at Miramare were always higher compared to the other MPAs, likely in relation to peculiar habitat characteristics. Density of T. pavo declined significantly from south to north, thus confirming the thermophily of this species. Present data point out the importance of monitoring marine fish diversity through long-term surveys across a wide spatial scale, in order to detect the early effects of water warming and to develop future plans of management and conservation.

Diversity, abundance and seasonal variation of the ichthyofauna associated with shrimp farming in a tropical estuary in northeastern Brazil

The precarious nature of the existing data on marine fish diversity on a global scale is accentuated in tropical areas, where taxonomic inventories of fish species are particularly incomplete. In the present study, we investigated the diversity, abundance and seasonal variation of the ichthyofauna associated with shrimp (Litopenaeus vannamei Boone, 1931) farming in a tropical estuary in northeastern Brazil. The experimental data were obtained at an aquaculture farm located on margins of the Guarairas lagoon (06°12′S, 35°09′W) in the state of Rio Grande do Norte. We sampled four shrimp culture cycles carried out from April to November 2005 during the rainy and dry seasons. Fishes were harvested at the termination of each culture cycle. We collected 36,681 fishes, comprising 26 families and 54 species. Shrimp culture cycles conducted in the dry season presented a more diverse fish community, albeit less abundant, than culture cycles carried out in the wet period. The most abundant families were Engraulidae in the wet season and Scianidae in the dry period. Juveniles of the engraulid Lycengraulis grossidens (Agassiz, 1989), a marine migrant, represented 87.67 % of total abundance in the wet season and 35.26 % of all individuals in the dry period. In conclusion, this study provides evidence of an abundant and diverse ichthyofauna associated with shrimp farming in northeastern Brazil. It also points to the necessity of finding alternatives to mitigate the entrainment of larval and juvenile fishes in shrimp ponds.

A long-bodied centriscoid fish from the basal Eocene of Kabardino-Balkaria, northern Caucasus, Russia

The Paleocene-Eocene transition is of crucial interest for interpreting the Cenozoic evolutionary radiation of vertebrates. A substantial increase of the number of vertebrate families occurred between the Late Paleocene and Early Eocene, with the appearance of most of the representatives of extant lineages. Basal Eocene marine fish diversity is currently poorly known, exclusively restricted to two assemblages from Denmark and Turkmenistan, respectively. Exceptionally well-preserved articulated skeletal remains of fishes have recently been discovered from a basal Eocene sapropelitic layer exposed along the Kheu River in the Republic of Kabardino-Balkaria, northern Caucasus, Russia. Here, we report on Gerpegezhus paviai gen. et sp. nov., a new peculiar syngnathoid fish from this new Ciscaucasian locality. The morphological structure of the single available specimen suggests that it is the first long-bodied member of the superfamily Centriscoidea, representing the sole member of the new family Gerpegezhidae, which forms a sister pair with the extant family Centriscidae.

Advanced approaches to studying the population diversity of marine fishes: New opportunities for fisheries control and management

Recent conceptual and technological advances now enable fisheries geneticists to detect and monitor the dynamics and distribution of marine fish populations more effectively than ever before. Information on the extent of genetically-based divergence among populations, so-called "population diversity", is crucial in the quest to manage exploited living resources sustainably since it endows evolutionary potential in the face of environmental change. The generally limited dialogue between scientists, fisheries managers and policy makers, however, continues to constrain integration of population genetic data into tangible policy applications. Largely drawing on the approach and outputs from a European research project, FishPopTrace, we provide an example how the uncovering of marine fish population diversity enables players from genetics, forensics, management and the policy realm to generate a framework tackling key policy-led questions relating to illegal fishing and traceability. We focus on the use of single-nucleotide polymorphisms (SNPs) in European populations of cod, herring, hake and common sole, and explore how forensics together with a range of analytical approaches, and combined with improved communication of research results to stakeholders, can be used to secure sufficiently robust, tractable and targeted data for effective engagement between science and policy. The essentially binary nature of SNPs, together with generally elevated signals of population discrimination by SNPs under selection, allowed assignment of fish to populations from more areas and with higher certainty than previously possible, reaching standards suitable for use in a court of law. We argue that the use of such tools in enforcement and deterrence, together with the greater integration of population genetic principles and methods into fisheries management, provide tractable elements in the arsenal of tools to achieve sustainable exploitation and conservation of depleted marine fish stocks.

Evaluating a habitat template model's predictions of marine fish diversity on the Scotian Shelf and Bay of Fundy, Northwest Atlantic

Abstract Fisher, J. A. D., Frank, K. T., Kostylev, V. E., Shackell, N. L., Horsman, T., and Hannah, C. G. 2011. Evaluating a habitat template model's predictions of marine fish diversity on the Scotian Shelf and Bay of Fundy, Northwest Atlantic. – ICES Journal of Marine Science, 68: 2096–2105. Habitat template models that integrate physical, chemical, and biological data have the potential to explain geographic variation in life-history traits within assemblages and to predict locations where species will be most vulnerable to anthropogenic impact. A previously developed model based on spatial variations in scope for growth (SG) and natural disturbance (ND) for the Scotian Shelf/Bay of Fundy was tested for its ability to predict fish life-history traits, species diversity, and community composition using trawl survey data. Of 30 dominant fish species, large, slow-growing ones most vulnerable to overexploitation tended to be found in naturally stable habitats. Among consistently co-occurring groups, functional differentiation, rather than similarity of life history, characterized assemblages, whereas among survey strata, species richness peaked at intermediate levels of ND and species evenness increased with average SG. Community composition was significantly correlated with both habitat variables, declined by 40% through time preceding structural changes on the eastern Scotian Shelf, but geographic distance, depth, and bottom temperature remained more strongly related to composition. The results revealed compelling matches between template predictions and patterns of fish species diversity, but low variation in diversity of life history, and mobility of fish may account for some of the weaker matches to model predictions.

Marine fish diversity: history of knowledge and discovery (Pisces)

A new monotypic genus, Bloszykiella africana gen. nov., sp. nov. (Mesostigmata: Uropodina: Uropodidae) is described on the basis of two females and one deutonymph found in soil samples from Tanzania. The new genus is unusual among Uropodina in having large strongly dentate chelicerae.

The relationship between marine fronts and fish diversity in the Patagonian Shelf Large Marine Ecosystem

AbstractAim To evaluate the relationship between marine fronts and (1) fish diversity patterns, (2) fish biomass distribution, and (3) fish assemblage structure.Location Patagonian Shelf, Southwestern Atlantic Ocean.Methods Three main frontal systems and eight nearby zones (frontal vs. non‐frontal areas) were compared. An extensive fishery database, obtained during an a priori sampling scheme (spatial resolution 1 × 1) from 1978 to 1979, was employed. Analyses of 248 trawling stations were performed using a combination of diversity measures (species richness, Shannon diversity and evenness), biomass analyses and multivariate analyses [nonparametric analysis of similarity (ANOSIM), non‐metric multidimensional scaling ordination (NMDS) and similarity percentages (SIMPER)] to evaluate the effect of fronts on fish communities.Results In total, 46 fish taxa were identified. Demersal fish diversity increased at the tidal front of Península Valdés but decreased in the frontal zones of the Southern Shelf‐Break and Magellan frontal systems. The richness and biomass of pelagic fish were higher at the Península Valdés Tidal Front, while the biomass of demersal fish was higher at its non‐frontal counterpart. Fish diversity did not differ consistently along the Northern Shelf‐Break Front. However, a higher fish biomass was registered at the non‐frontal zone. Demersal and pelagic fish assemblages differed between frontal and non‐frontal zones.Main conclusions The Patagonian Shelf Large Marine Ecosystem has diverse frontal types that appear to have different effects on fish diversity and assemblage structure. Seasonal (tidal) or permanent fronts have different effects on the parameters analysed, which could be due to productivity–diversity relationships. The Península Valdés Tidal Front, a relatively short temporal scale system, demonstrates a stronger influence on fish diversity, biomass and assemblage structure than the other frontal areas studied. The seasonality of nutrient input owing to frontogenesis, which begins during the austral spring, may play an important role in determining local diversity. At permanent frontal features, diversity decreases when the nutrient availability is high. This is potentially because, when food resources increase, a few species become dominant.

Marine Fish Diversity and Composition in the Mid-Atlantic and South Atlantic Bights

Abstract We sampled fishes from nearshore, continental shelf (≈30 m) to shelf-slope, deep-water habitats (≈100 m) in the Mid-Atlantic Bight (MAB) and South Atlantic Bight (SAB) during winter (2005) to explore compositional differences among temperatures and depths. Trawl surveys conducted by the National Marine Fisheries Service do not typically sample winter fish assemblages concurrently from both the MAB and SAB, although increased concern over changes in distribution of species such as Pterois volitans (Lionfish) may warrant such studies. We collected 41 families and 68 species of fish, and found that temperature and depth influenced their distribution. More species were collected in the SAB where temperature was 10 °C higher. At nearshore sites of SAB, we collected reef fishes (Chaetodontidae; Fistulariidae) and Stenotomus chrysops (Scup). At deep water sites of SAB, we collected Ophichthidae, Acropomatidae, and Scorpaenidae. Assemblages of the MAB were dominated by Squalus acanthias (Spiny Dogfish), ...

The completeness of taxonomic inventories for describing the global diversity and distribution of marine fishes

Taxonomic inventories (or species censuses) are the most elementary data in biogeography, macroecology and conservation biology. They play fundamental roles in the construction of species richness patterns, delineation of species ranges, quantification of extinction risk and prioritization of conservation efforts in hot spot areas. Given their importance, any issue related to the completeness of taxonomic inventories can have far-reaching consequences. Here, we used the largest publicly available database of georeferenced marine fish records to determine its usefulness in depicting the diversity and distribution of this taxonomic group. All records were grouped at multiple spatial resolutions to generate accumulation curves, from which the expected number of species were extrapolated using a variety of nonlinear models. Comparison of the inventoried number of species with that expected from the models was used to calculate the completeness of the taxonomic inventory at each resolution. In terms of the global number of fish species, we found that approximately 21% of the species remain to be described. In terms of spatial distribution, we found that the completeness of taxonomic data was highly scale dependent, with completeness being lower at finer spatial resolutions. At a 3 degrees (approx. 350km2) spatial resolution, less than 1.8% of the world's oceans have above 80% of their fish fauna currently described. Censuses of species were particularly incomplete in tropical areas and across the entire range of countries' gross domestic product (GDP), although the few censuses nearing completion were all along the coasts of a few developed countries or territories. Our findings highlight that failure to quantify the completeness of taxonomic inventories can introduce substantial flaws in the description of diversity patterns, and raise concerns over the effectiveness of conservation strategies based upon data that remain largely precarious.

Priority areas for conservation of Western Australian coastal fishes: A comparison of hotspot, biogeographical and complementarity approaches

Western Australia has an extensive coastline ranging from the tropical north to the temperate south, with a high diversity of neritic marine fishes. Distribution data of 1855 neritic fish species were used to compare a range of methods for identifying priority areas for their conservation. Species richness and endemism richness hotspots, biogeographic zoning and complementarity analysis were tested for their efficiency at representing the total suite of species. The hotspot approaches demonstrated low efficiency, as the sections of coastline selected were grouped together in isolated geographic locations and relatively few of the total suite of neritic fish species were represented. Biogeographic zoning divided the coast of Western Australia into six regions, and as such, priority areas were selected around the entire coastline, which resulted in fairly high levels of efficiency. However, the complementarity analysis proved to be the most efficient method, as >95% of all neritic fish species could be represented in six, appropriately located, 100 km long sections of coastline. Complementarity analysis indicated a total of 26 priority areas for neritic fish conservation, which were spread around the entire coast of Western Australia. However, as current marine conservation measures in Western Australia are focused on the west and northwest coasts, this study highlighted the need for marine conservation efforts to be extended to cover the north and south coasts.

Karyotype diversification in fishes of the Balistidae, Diodontidae and Tetraodontidae (Tetraodontiformes)

Among the great marine fish diversity, the Order Tetraodontiformes is remarkable by presenting post-Perciformes modern features, representing one of the major branches of the teleosteans radiation. Patterns of chromosomal evolution in this group are not fully understood. In the present work, cytogenetical analyses were carried out in the species Balistes vetula (2n=44; FN=44) and Melichthys niger (2n=40 and FN=40) (Balistidae), Chilomycterus antennatus (2n=52; 6M+46st/a, FN=58) (Diodontidae) and Sphoeroides testudineus (2n=46; 18m+4sm+6st+18a, FN=74) (Tetraodontidae), collected along the Brazilian coast and Saint Pauls Rocks. All spe- cies presented Ag-NORs sites on a single chromosomal pair. Heterochromatic regions in this group are reduced and located at centromeric position over most of chromosomal pairs. The evolutionary patterns of chromosomal changes were diverse in the distinct Tetraodontiformes families. In Balistidae, the evolution process seems to be determined by in tandem or centric fusions, followed by pericentric inversions. The higher chromosomal number in Diodontidae indicates that centric fissions and pericentric inversions played an important role in the karyotypi- cal definition of this group. The Tetraodontidae S. testudineus displayed small chromosomes with a modal number shared with other species previously analyzed from this family. Such great karyotypical diversity is com- patible with a scenario of several modifications established by the adaptative irradiation of this group.

Studies on chilling sensitivity of zebrafish ( Danio rerio) oocytes

Human activity in the last few decades has had a devastating effect on the diversity of fresh water and marine fish. Further decline of fish population may have serious economic and ecological consequences. One of the most promising techniques to preserve fish population is to cryopreserve their germ cells. Cryopreservation has been successfully applied to fish sperm of many species, but there has been no success with fish embryo cryopreservation and fish oocyte cryopreservation has never been studied systematically. The aim of this study is to investigate the chilling sensitivity of fish oocytes. Experiments were conducted with zebrafish stage III (vitellogenic) and stage V (mature) oocytes, which were chilled at 10, 5, 0, −5 or −10 °C for 15 or 60 min using a low temperature bath. Control oocytes were kept at room temperature at 22 °C. Oocyte viability was assessed using three different methods: trypan blue staining (TB), thiazolyl blue tetrazolium bromide (MTT) staining and observation of germinal vesicle breakdown (GVBD). The results showed that zebrafish oocyte are very sensitive to chilling and their survival decreased with decreasing temperature and increasing exposure time periods. Normalised survivals assessed with TB staining after exposure to 0, −5 or −10 °C for 15 or 60 min were 90.1 ± 6.0, 77.8 ± 7.6, and 71.2 ± 9.3%, and 60.2 ± 3.8, 49.6 ± 6.7, and 30.4 ± 3.0%, respectively. The study found that the sensitivity of viability assessment methods increase in the order of MTT < TB < GVBD. It was found that stage III oocytes were more susceptible to chilling than stage V oocytes, and that individual female had a significant influence ( p<0.0001) on oocyte chilling sensitivity. Zebrafish oocyte chilling sensitivity may also be one of the limiting factors for development of protocol of their cryopreservation.