Lutjanus Kasmira Research Articles

Phylogeography pattern of Lutjanus kasmira in the Bengal Strait and the Arabian Sea

Lutjanus kasmira is one of the snappers occupying and commonly found in the Arabian Sea and the Bengal Strait. The purpose of this study was to examine the comparative phylogeography pattern of Lutjanus kasmira in the Bengal Strait and the Arabian Sea using the mitochondrial COI gene as a marker. The population sampled of Indonesia was taken from fish landing in Banda Aceh, Indonesia, while the population of India represented Bengal Strait, Oman, Yemen, Djibouti and Somalia respresented Arabian sea was retrieved from the NCBI Genbank. The extraction method was carried out using a modified C-TAB protocol. In this study at total of 47 sequences were analysed that produced 22 haplotypes where 18 haplotypes distributed in the Arabian Sea and 4 haplotypes from Bengal Strait. 10 samples of Oman population produced 6 haplotypes, 10 samples from Djibouti produced 5 haplotypes, 5 haplotypes from the population of Yemen, Somalia 2 haplotypes and India 1 haplotypes, respectively. Meanwhile, the Indonesian population, from 6 samples, produced 3 haplotypes. L. kasmira population from Arabian Sea and Bengal strait had no connectivity. The highest haplotype diversity (Hd) value was found in Oman population of 0.956 and the lowest found in Somalia population, while Indonesia population has a moderate genetic diversity.

First Molecular Identification of a Goussia Parasite from a New World Invasive Blenny.

Introduced or invasive fish are susceptible to new parasites but can simultaneously carry infectious parasites from their native range towards new hosts. Screening these parasites is key to address the health of fish populations and spread of diseases. In this study, we sequenced a Coccidia parasite, for the first time from the blenny Omobranchus sewalli, introduced in the northern coast of Brazil with an Indo-Pacific origin. Only one individual was infected, its genetic sequence matched (over 99%) with two lineages of undetermined species, belonging to the genus Goussia, sequenced from three marine fish species (Mulloidichthys flavolineatus, Lutjanus kasmira, and Selar crumenophthalmus) in Hawaii. Phylogenetic analysis suggests considerable differentiation between the Goussia detected and other Goussia spp. sequenced from North Atlantic marine fish, thus we cannot exclude the possibly that this parasite was carried by O. sewalli from its native Indo-Pacific range.

Changes in population biology of three coral reef fishes in the South China Sea between 1998–1999 and 2016–2019

The decline of coral reefs and their fish has attracted worldwide attention. The South China Sea is the important center of coral reefs. Reef-fish is a crucial component in coral reef ecosystem. However, studies on the long-term variation in the biololgy of coral reef fish in the South China Sea are very lacking. To enhance our understanding of variation in reef fish biology in the South China Sea, we investigated long-term changes in some biological indicators of three dominant coral reef fishes (Lutjanus kasmira, Gnathodentex aureolineatus, and Cephalopholis urodeta) at the Yongshu Reef of the South China Sea between 1998–1999 and 2016–2019, and examined the effects of fishing and sea surface temperature on their biology. Compared with 1998–1999, average body length, average body mass, large fish indicator, feeding level and relative fatness of Lutjanus kasmira and Gnathodentex aureolineatus decreased in 2016–2019, but Cephalopholis urodeta did not. The relative fatness was positively correlated with the feeding level, which indicated that the decline of feeding level decreased the relative fatness. Fishing had the most important negative impact on biological changes. In the past two decades, Lutjanus kasmira had the most obvious decline in size and relative fatness, followed by Gnathodentex aureolineatus, but Cephalopholis urodeta had almost no decline. We hypothesized that different coral reef fishes have different abilities to maintain population stability under external pressures, and the differences in vulnerability of three fish species were the main reasons for their different responses to external pressures. To promote the conservation of coral reef fish, we recommend taking rigorous management to protect habitat.

Morphometric and genetic variations of four dominant species of snappers (Lutjanidae) harvested from the Northern Coast of Aceh waters, Indonesia

Lutjanus commonly known as snappers are economical fishes in the world, including in Indonesia. They have high morphological similarities and are difficult to distinguish. Therefore, this study aimed to validate the taxonomic status and kinship of four dominant snappers harvested from the northern coastal waters of Aceh, Indonesia, namely Lutjanus bengalensis, Lutjanus kasmira, Lutjanus gibbus, and Lutjanus fulviflamma. The samples were collected from Pulo Aceh and Lampulo fish landings. A total of 60 samples of each species were used for morphometric analysis using the traditional morphometric approach, while five from each of them served as samples for the genetic analysis with the COI gene. Morphological analysis showed that the four fish species were categorized into 3 different groups, where L. bengalensis and L. kasmira were in the same group. The genetic analysis revealed that they were grouped into four different clades, but L. bengalensis and L. kasmira were located in the same sister clade, indicating genetic closeness. L. bengalensis, L. kasmira, L. gibbus, and L. fulviflamma had two, three, three, and four haplotypes, respectively. Based on the results, the COI gene successfully distinguished the four species of snapper, where L. bengalensis and L. kasmira had morphological and genetic similarities. Furthermore, L. fulviflamma had higher genetic diversity than the others.

Genetic Diversity Analysis of Different Populations of Lutjanus kasmira Based on SNP Markers

Lutjanus kasmira belongs to the family Lutjanidae. Over the past 20 years, the L. kasmira population in the South China Sea has been shrinking due to climate change, pressure from human activities, and inadequate food supplies. In this study, single nucleotide polymorphism (SNP) data obtained from restriction site-associated DNA sequencing (RAD-seq) were used to assess the genetic diversity of L. kasmira in Zhubi Dao (ZB) and Meiji Dao (MJ). The genome-wide nucleotide diversity (π) of the ZB population and MJ population was 0.02478 and 0.02154, respectively. The inbreeding coefficient (Fis) of the ZB population and MJ population was −0.18729 and 0.03256, respectively. The genetic differentiation (Fst) between the ZB and MJ subpopulations was 0.00255102. The expected heterozygosity (He) of individuals from ZB and MJ was 0.33585 and 0.22098, respectively. The observed heterozygosity (Ho) of individuals from the ZB population and MJ population was 0.46834 and 0.23103, respectively. Although the ZB and MJ populations did not have significant genetic differences, the genetic differentiation between them was confirmed using population structure, phylogenetic, and principal component analyses. These results indicated that the genetic diversity of the ZB and MJ populations was relatively low at the genome level, and that their genetic differences were small.

Artefactual Suboptimal Fixation Effect to Nuclear Staining on Erythrocytes of Lutjanus kasmira (Forsskål 1775)

This research presents the unusual staining characteristic of the teleosts red blood cells–the common bluestripe snapper Lutjanus kasmira, caught at Toc Tan (Allison) Reef, Truong Sa Archipelago, Vietnam, due to side effects of the delayed staining procedure. In addition to the quantitative data measured, the results of microscopic image research showed that, on slides performed with the delayed Romanovsky staining procedure using Giemsa dye, the cell "nucleus" was not dye-stained as seen in the erythrocytes of much other fish. The AFM and SEM images of blood slides show that the structure of the nuclear zone and the nuclear membrane was destroyed. Although methanol is used as one of the common fixatives in biology, the delayed staining still causes artifactual side effects, disrupts the structure of the red blood cell nucleus and can cause confusion when studying cytogenetics.

Length-weight relationship and gonadal index of juvenile bluestripe snapper Lutjanus kasmira (Forsskål, 1775) in the waters around Tanamon Village South Minahasa

This study aims to determine the length-weight relationship, growth patterns, and gonadal index of juvenile bluestripe snapper Lutjanus kasmira. Samples were collected using a hand line with a hook numbered 3 and a monofilament fishing line numbered 80. Sampling activities were carried out on July 26th – August 4th, August 26th - September 4th, and October 10th, 2020. A total of 70 fish, 22 females and 48 males was caught. Female length distribution ranged from 104 to 150 mm with a weight range of 18.19-55.87 g, while male length ranged from 107 to 150 mm in length with a weight of 19.00-57.00 g. The length-weight relationship was indicated with W= 0.0177L2.9344 (R2=0,7816) for males and W = 0.012L3.0817 (R2=0,8976) for females with isometric growth pattern. The length-weight relationship for combined sexes was W= 0.0156L2.9816 (R2=0,8186) with an isometric growth pattern. The gonadal maturity for all samples was at immature and developing stages. The gonadal index in female snapper at immature was 0.16 and developing was 0.41, whereas the male gonadal maturity index at immature was 0.14 and developing was 0.38.Keywords: Lutjanus kasmira; length-weight; gonad maturity; gonadal indexAbstrakPenelitian ini bertujuan untuk mengetahui hubungan panjang berat, pola pertumbuhan dan indeks gonad ikan kakap Lutjanus kasmira. Sampel ikan ditangkap menggunakan pancing ulur mata pancing nomor 3 dan tali monofilament nomor 80. Aktivitas pengambilan sampel dilakukan masing-masing pada 26 Juli-4 Agustus, 26 Agustus-4 September 2020, dan 10 Oktober 2020. Sebanyak 70 individu sampel diperoleh, 22 betina dan 48 jantan. Sebaran ukuran panjang ikan betina 104-150 mm dan berat 18,19-55,87 g. Sebaran ukuran panjang ikan jantan 107-150 mm dan berat 19,00-57,00 g. Hubungan panjang-berat diperoleh W= 0,0177L2,9344 (R2=0,7816) untuk jantan dan W = 0,012L3,0817 (R2=0,8976) untuk betina dengan pola pertumbuhan isometrik. Gabungan ikan kakap jantan dan betina diperoleh W= 0,0156L2,9816 (R2=0,8186) dengan pola pertumbuhan isometrik. Tingkat kematangan gonad (TKG) terhadap seluruh sampel baik jantan maupun betina berada pada TKG I (belum matang) dan TKG II (berkembang). Indeks gonad pada ikan kakap betina pada TKG I sebesar 0,16 dan TKG II sebesar 0,41. Indeks kematangan gonad ikan kakap jantan pada TKG I sebesar 0,14 dan TKG II sebesar 0,38.Kata Kunci: Lutjanus kasmira, panjang-berat, kematangan gonad, indeks gonad

Deep Insights into Gut Microbiota in Four Carnivorous Coral Reef Fishes from the South China Sea.

Investigations of gut microbial diversity among fish to provide baseline data for wild marine fish, especially the carnivorous coral reef fishes of the South China Sea, are lacking. The present study investigated the gut microbiota of four carnivorous coral reef fishes, including Oxycheilinus unifasciatus, Cephalopholis urodeta, Lutjanus kasmira, and Gnathodentex aurolineatus, from the South China Sea for the first time using high-throughput Illumina sequencing. Proteobacteria, Firmicutes, and Bacteroidetes constituted 98% of the gut microbiota of the four fishes, and 20 of the gut microbial genera recovered in this study represent new reports from marine fishes. Comparative analysis indicated that the four fishes shared a similar microbial community, suggesting that diet type (carnivorous) might play a more important role in shaping the gut microbiota of coral reef fishes than the species of fish. Furthermore, the genera Psychrobacter, Escherichia-Shigella, and Vibrio constituted the core microbial community of the four fishes, accounting for 61–91% of the total sequences in each fish. The lack of the genus Epulopiscium in the four fishes was in sharp contrast to what has been found in coral reef fishes from the Red Sea, in which Epulopiscium was shown to be the most dominant gut microbial genus in seven herbivorous coral reef fishes. In addition, while unique gut microbial genera accounted for a small proportion (8–13%) of the total sequences, many such genera were distributed in each coral reef fish species, including several genera (Endozoicomonas, Clostridium, and Staphylococcus) that are frequently found in marine fishes and 11 new reports of gut microbes in marine fishes. The present study expands our knowledge of the diversity and specificity of gut microbes associated with coral reef fishes.

Comparative phylogeography of reef fishes from the Gulf of Aden to the Arabian Sea reveals two cryptic lineages

The Arabian Sea is a heterogeneous region with high coral cover and warm stable conditions at the western end (Djibouti), in contrast to sparse coral cover, cooler temperatures, and upwelling at the eastern end (southern Oman). We tested for barriers to dispersal across this region (including the Gulf of Aden and Gulf of Oman), using mitochondrial DNA surveys of 11 reef fishes. Study species included seven taxa from six families with broad distributions across the Indo-Pacific and four species restricted to the Arabian Sea (and adjacent areas). Nine species showed no significant genetic partitions, indicating connectivity among contrasting environments spread across 2000 km. One butterflyfish (Chaetodon melannotus) and a snapper (Lutjanus kasmira) showed phylogenetic divergences of d = 0.008 and 0.048, respectively, possibly indicating cryptic species within these broadly distributed taxa. These genetic partitions at the western periphery of the Indo-Pacific reflect similar partitions recently discovered at the eastern periphery of the Indo-Pacific (the Hawaiian and the Marquesan Archipelagos), indicating that these disjunctive habitats at the ends of the range may serve as evolutionary incubators for coral reef organisms.

Distribution and abundance of the introduced snapper Lutjanus kasmira (Forsskål, 1775) on shallow and mesophotic reefs of the Northwestern Hawaiian Islands

Distribution and abundance of the introduced snapper Lutjanus kasmira (Forsskål, 1775) on shallow and mesophotic reefs of the Northwestern Hawaiian Islands

Validity of a blue stripe snapper, Lutjanus octolineatus (Cuvier 1828)and a related species, L. bengalensis (Bloch 1790) with a new species (Pisces; Lutjanidae) from the Arabian Sea.

Lutjanus octolineatus (Cuvier 1828), previously considered a junior synonym of Lutjanus bengalensis (Bloch 1790), is shown to be a valid species and lectotypes are designated. Both species are redescribed. The two species have overlapping distributions in the Indian Ocean, but are clearly separable by different dorsal-fin spine counts, blue-striped pattern on the body and the presence or absence of a subocular extension of cheek scales. Lutjanus octovittata (Valenciennes 1830), formerly assigned to synonymy of L. bengalensis, is considered a junior synonym of L. octolineatus based on examination of the holotype. Lutjanus sapphirolineatus n. sp., a species formerly misidentified as L. bengalensis, is described based on 10 specimens from Oman and Somalia. The new species differs from the three species above by a combination of different characters. Analysis of the mitochondrial cytochrome c oxidase subunit 1 (CO1, 603 bp) genetic marker, also strongly supports the validity of each species of the blue-striped snapper complex as distinct.

Feeding ecology of some fish species occurring in artisanal fishery of Socotra Island (Yemen)

The demersal species Lethrinus borbonicus, Lethrinus mahsena, Lethrinus microdon, Lethrinus nebulosus, Lutjanus bohar, Lutjanus gibbus, Lutjanus kasmira, Epinephelus fasciatus, Epinephelus stoliczkae, Carangoides gymnostethus and Euthynnus affinis are important coastal fishes species of the northern coast of Socotra (Yemen), exploited by local fishery. The biology and feeding ecology of these species are poorly known in the area. A total of 1239 specimens were sampled from the main fishing landing site of the island (Hadibo). Total length and weight were measured, stomach contents were analyzed, diet overlap, Fulton's Condition index, and trophic levels were estimated. C. gymnostethus, L. microdon and L. kasmira occupied the highest position (T=4.50), L. nebulosus occupied the lower one (TL=3.41). The role of the increasing abundance of small pelagic fish in the diet of many species after the upwelling event is evident, but also different feeding strategies are reported, according to fish ecology.

Comparative phylogeography of the western Indian Ocean reef fauna

Assessing patterns of connectivity at the community and population levels is relevant to marine resource management and conservation. The present study reviews this issue with a focus on the western Indian Ocean (WIO) biogeographic province. This part of the Indian Ocean holds more species than expected from current models of global reef fish species richness. In this study, checklists of reef fish species were examined to determine levels of endemism in each of 10 biogeographic provinces of the Indian Ocean. Results showed that the number of endemic species was higher in the WIO than in any other region of the Indian Ocean. Endemic species from the WIO on the average had a larger body size than elsewhere in the tropical Indian Ocean. This suggests an effect of peripheral speciation, as previously documented in the Hawaiian reef fish fauna, relative to other sites in the tropical western Pacific. To explore evolutionary dynamics of species across biogeographic provinces and infer mechanisms of speciation, we present and compare the results of phylogeographic surveys based on compilations of published and unpublished mitochondrial DNA sequences for 19 Indo-Pacific reef-associated fishes (rainbow grouper Cephalopholis argus, scrawled butterflyfish Chaetodon meyeri, bluespot mullet Crenimugil sp. A, humbug damselfish Dascyllus abudafur/Dascyllus aruanus, areolate grouper Epinephelus areolatus, blacktip grouper Epinephelus fasciatus, honeycomb grouper Epinephelus merra, bluespotted cornetfish Fistularia commersonii, cleaner wrasse Labroides sp. 1, longface emperor Lethrinus sp. A, bluestripe snapper Lutjanus kasmira, unicornfishes Naso brevirosris, Naso unicornis and Naso vlamingii, blue-spotted maskray Neotrygon kuhlii, largescale mullet Planiliza macrolepis, common parrotfish Scarus psicattus, crescent grunter Terapon jarbua, whitetip reef shark Triaenodon obesus) and three coastal Indo-West Pacific invertebrates (blue seastar Linckia laevigata, spiny lobster Panulirus homarus, small giant clam Tridacna maxima). Heterogeneous and often unbalanced sampling design, paucity of data in a number of cases, and among-species discrepancy in phylogeographic structure precluded any generalization regarding phylogeographic patterns. Nevertheless, the WIO might have been a source of haplotypes in some cases and it also harboured an endemic clade in at least one case. The present survey also highlighted likely cryptic species. This may eventually affect the accuracy of the current checklists of species, which form the basis of some of the recent advances in Indo-West Pacific marine ecology and biogeography.

Forecasting the success of invasive marine species; lessons learned from purposeful reef fish releases in the Hawaiian Islands

Eleven grouper, snapper, and emperor fish species were intentionally released in the Hawaiian Islands spanning the years 1955–1961 to produce new fisheries. Within 15 years, three of the introduced species established self-sustaining populations and eight did not. Two species, Lutjanus kasmira and Cephalopholis argus, are now considered invasive. We report on the results of a biophysical computer model which combines the life history traits of the inductees with prevailing oceanographic conditions in the Hawaiian Islands to hindcast the fate of the introduced fish. This comparative study is valuable in providing numeric insight into the characteristics that predispose fish introduced outside their native range to becoming invasive. Simulations created by the model spanning the years 1955–1970 succeeded to reproduce the establishment of the three species now found in the Hawaiian Islands and also replicated the failure of those fish that did not establish. Our results suggest that mortality rate, tolerance to water depth, age to maturity, and the quantity of individuals released are the best predictors of the establishment of the introduced fish in the Hawaiian Islands.

Phylogenetic relationships of tropical eastern Pacific snappers (Lutjanidae) inferred from mitochondrial DNA sequences

A total of 2,206 base pairs of coding sequences of mitochondrial DNA from nine of 10 lutjanine (Lutjanidae) species endemic to the eastern Pacific Ocean were used in a phylogenetic analysis to infer species relationships among lutjanines on either side of the Isthmus of Panama. Monotypic Hoplopagrus (guentherii) appears to be at the base of all lutjanines assayed to date and represents the first of five, eastward dispersal events of lutjanines from the Indo-Pacific to the Americas. Diversification of lutjanines in the Americas appears to have occurred primarily in the western Atlantic Ocean (Caribbean Sea) and been aided by an early Miocene eastward-flowing current and by more optimal lutjanine habitat in the warmer Caribbean waters. Five geminate species pairs in five, strongly supported clades were identified. In three, the trans-isthmian geminate species in the eastern Pacific belonged to clades in which basal and other members of the clade are endemic to the western Atlantic, suggesting that the ancestor to each species geminate pair dispersed westward into the eastern Pacific prior to closure of connections between the two oceans; the opposite occurred in one of the clades. The fifth clade contained only two species, one on either side of the Isthmus. Diversification in life-history and other traits in each geminate species pair appears to have been slight. Five lutjanine species possessing horizontal blue stripes (the blue-lined complex) and distributed from the western Indian Ocean to the eastern Pacific formed a strongly supported monophyletic clade. The lone blue-lined species in the eastern Pacific (Lutjanus viridis) could be conspecific with its highly dispersive sister species (Lutjanus kasmira) from the Indo-Pacific. The chronology of lutjanine diversification and closure of seawater exchange between the two oceans is briefly discussed.

Length-based assessment of coral reef fish populations in the main and northwestern Hawaiian islands.

The coral reef fish community of Hawaii is composed of hundreds of species, supports a multimillion dollar fishing and tourism industry, and is of great cultural importance to the local population. However, a major stock assessment of Hawaiian coral reef fish populations has not yet been conducted. Here we used the robust indicator variable “average length in the exploited phase of the population ()”, estimated from size composition data from commercial fisheries trip reports and fishery-independent diver surveys, to evaluate exploitation rates for 19 Hawaiian reef fishes. By and large, the average lengths obtained from diver surveys agreed well with those from commercial data. We used the estimated exploitation rates coupled with life history parameters synthesized from the literature to parameterize a numerical population model and generate stock sustainability metrics such as spawning potential ratios (SPR). We found good agreement between predicted average lengths in an unfished population (from our population model) and those observed from diver surveys in the largely unexploited Northwestern Hawaiian Islands. Of 19 exploited reef fish species assessed in the main Hawaiian Islands, 9 had SPRs close to or below the 30% overfishing threshold. In general, longer-lived species such as surgeonfishes, the redlip parrotfish (Scarus rubroviolaceus), and the gray snapper (Aprion virescens) had the lowest SPRs, while short-lived species such as goatfishes and jacks, as well as two invasive species (Lutjanus kasmira and Cephalopholis argus), had SPRs above the 30% threshold.

Bioaccumulation of Heavy Metals in Fish, Squids and Crustaceans from the Red Sea, Jeddah Coast, Saudi Arabia

Concentration of Cadmium, Copper, Lead, Zinc and Mercury were determined in the muscles, gills and liver of ten fish species (Epinephelus areolatus, Epinephelus radiates, Anthias squamipinnis, Plectorhinchus chaetodonoides, Snubnose emperor, Dicentrarchus labrax, Acanthopagrus bifasciatus, lutjanus kasmira, lutjanus ehrenbergii and Acanthurus gahhm) as well as three specimens of crustaceans (Metapenaeus dalli, Panulirus penicillatus and Portunus petagicus) and two Specimens of squids (Parateuthis tunicate and Chtenopteryx sicula) collected from Jeddah coastal water during 2014. The obtained results declared that, the average concentrations of heavy metals were as follows: Cd (0.098, 0.20, 0.106), Cu (0.358, 0.327, 1.536), Pb (0.3, 0.257, 0.196), Zn (3.00, 7.390, 4.999) μg/g wet weight in the muscle, gills and liver, respectively. While, the concentration of Hg was invariably undetectable in all samples of different organs of the collected fish species. The average concentration of Cd, Cu, Pb, Zn and Hg in the soft part of the investigated crustaceans (Metapenaeus dalli, Panulirus penicillatus and Portunus petagicus) and squids (Parateuthis tunicate and Chtenopteryx sicula) were relatively higher compared with the muscle tissues in the examined fish species. The results of bioconcentration factor (BCFs) indicated that among examined metals Zn was the most readily absorbed by fish and the highest BAFs for examined fish species were determined in gill of Snubnose emperor.

An Invasive Fish and the Time-Lagged Spread of Its Parasite across the Hawaiian Archipelago

Efforts to limit the impact of invasive species are frustrated by the cryptogenic status of a large proportion of those species. Half a century ago, the state of Hawai'i introduced the Bluestripe Snapper, Lutjanus kasmira, to O'ahu for fisheries enhancement. Today, this species shares an intestinal nematode parasite, Spirocamallanus istiblenni, with native Hawaiian fishes, raising the possibility that the introduced fish carried a parasite that has since spread to naïve local hosts. Here, we employ a multidisciplinary approach, combining molecular, historical, and ecological data to confirm the alien status of S. istiblenni in Hawai'i. Using molecular sequence data we show that S. istiblenni from Hawai'i are genetically affiliated with source populations in French Polynesia, and not parasites at a geographically intermediate location in the Line Islands. S. istiblenni from Hawai'i are a genetic subset of the more diverse source populations, indicating a bottleneck at introduction. Ecological surveys indicate that the parasite has found suitable intermediate hosts in Hawai'i, which are required for the completion of its life cycle, and that the parasite is twice as prevalent in Hawaiian Bluestripe Snappers as in source populations. While the introduced snapper has spread across the entire 2600 km archipelago to Kure Atoll, the introduced parasite has spread only half that distance. However, the parasite faces no apparent impediments to invading the entire archipelago, with unknown implications for naïve indigenous Hawaiian fishes and the protected Papahānaumokuākea Marine National Monument.

Ontogenetic trajectories of otolith shape during shift in habitat use: Interaction between otolith growth and environment

Otolith morphometrics has been shown to provide a practical basis for stock discrimination and ageing. This approach has been extensively used by fisheries scientists over the last decades. However, the determinants of otolith shape are not fully understood and shape apparently results from the synergistic action of various confounding factors. In this study, I used a geometric morphometric approach to quantitatively investigate the concomitant effect of local environmental conditions and ontogeny on otolith shape. I specifically focused on the ontogenetic trajectories of otolith shape in a coral reef fish (Lutjanus kasmira) during an ontogenetic shift in habitat use, from juveniles settled in the estuary to adults inhabiting either the channel or the outer-reef off French Polynesia. Data emphasize that both ontogeny and environmental conditions influence otolith shape in an interactive way, potentially mediated by growth rate. More specifically, during the early life stages living in the estuary, otolith shape is mainly linked to fish size, indicating an ontogenetically determined development that induces an overall reshaping of the otoliths. In contrast, the transition from the estuarine to the reef life is considered as a crucial phase in fish life history, as revealed by an important change in the ontogenetic rate and direction of the otolith development for both habitats. After the shift in habitat use, otolith demonstrated divergent ontogenetic growth patterns, not in terms of heterochrony but in the magnitude and direction of morphological changes. This indicates that growth axis can be completely reshaped by environmental conditions, with respect to allometric component. This information is fundamental if otolith shape is to be used in fisheries management as an effective tool for modeling age-structured populations and stocks as a function of the use made of the habitat during life span.

Genetic connectivity of the reef fishLutjanus kasmiraat the scale of the western Indian Ocean

Examining the genetic structure of species allows an estimate of the level of evolutionary connectivity between localities; this information is important for marine biodiversity protection, in particular, for the delineation of marine protected areas. In this context, a total of 601 Lutjanus kasmira (Forsskål, 1775) were sampled in 16 localities of the western Indian Ocean and analyzed with both mitochondrial cytochrome b sequencing and eight microsatellite loci genotyping. Both genetic markers indicate that differentiation was not significant even between samples separated by more than 4000 km. This absence of genetic differentiation among samples was favored by ecological plasticity of the species and is now ensured by resultant high levels of dispersal. Nevertheless, some significant genetic structure was detected for the areas of Mauritius and Moroni, as well as within populations in all localities, which will have to be explained by additional studies on local processes.