Marine Bony Fishes Research Articles

Is it worthy to use environmental DNA instead of scientific trawling or video survey to monitor taxa in soft-bottom habitats?

Non-extractive techniques such as video analysis are increasingly used by scientists to study marine communities instead of extractive methods such as trawling. Currently, environmental DNA (eDNA) analysis is seen as a revolutionary tool to study taxonomic diversity. We aimed to determine which method is the most appropriate to describe fish and commercial invertebrate diversity comparing bottom trawl hauls, video transects and seawater eDNA. Our results reveal that video detected the lowest number of taxa and trawling the highest. eDNA analysis is powerful to describe marine bony fish communities, but some taxa of importance for the ecosystem such as elasmobranchs, crustaceans or molluscs are poorly detected. This may be due to several factors such as marker specificity, incomplete reference gene databases or low DNA release in the environment. For now, the various methods provide different information and none is exhaustive enough to be used alone for biodiversity characterisation.

Implications of dietary carbon incorporation in fish carbonates for the global carbon cycle

Marine bony fish are important participants in Earth's carbon cycle through their contributions to the biological pump and the marine inorganic carbon cycle. However, uncertainties in the composition and magnitude of fish contributions preclude their integration into fully coupled carbon-climate models. Here, we consider recent upwards revisions to global fish biomass estimates (2.7–9.5×) and provide new stable carbon isotope measurements that show marine fish are prodigious producers of carbonate with unique composition. Assuming the median increase (4.17×) in fish biomass estimates is linearly reflected in fish carbonate (ichthyocarbonate) production rate, marine fish are estimated to produce between 1.43 and 3.99 Pg CaCO3 yr−1, but potentially as much as 9.03 Pg CaCO3 yr−1. Thus, marine fish carbonate production is equivalent to or potentially higher than contributions by coccolithophores or pelagic foraminifera. New stable carbon isotope analyses indicate that a significant proportion of ichthyocarbonate is derived from dietary carbon, rather than seawater dissolved inorganic carbon. Using a statistical mixing model to derive source contributions, we estimate ichthyocarbonate contains up to 81 % dietary carbon, with average compositions of 28–56 %, standing in contrast to contents <10 % in other biogenic carbonate minerals. Results also indicate ichthyocarbonate contains 5.5–40.4 % total organic carbon. When scaled to the median revised global production of ichthyocarbonate, an additional 0.08 to 1.61 Pg C yr−1 can potentially be added to estimates of fish contributions to the biological pump, significantly increasing marine fish contributions to total surface carbon export. Our integration of geochemical and physiological analyses identifies an overlooked link between carbonate production and the biological pump. Since ichthyocarbonate production is anticipated to increase with climate change scenarios, due to ocean warming and acidification, these results emphasize the importance of quantitative understanding of the multifaceted role of marine fish in the global carbon cycle.

On the Evolution of Some Groups of Marine Bony Fishes in the Cenozoic of the Tethys and Paratethys

On the Evolution of Some Groups of Marine Bony Fishes in the Cenozoic of the Tethys and Paratethys

On the Evolution of Some Groups of Marine Bony Fishes in the Cenozoic of the Tethys and Paratethys

Data on the principal Cenozoic localities of marine bony fishes (represented by skeletal remains, not otoliths) from the territory of the development of the Tethys and Paratethys are presented. The historical development of many supra-generic taxa of the higher Teleostei (spiny-rayed) in the Cenozoic basins of the Tethys and Paratethys has been traced. The available paleontological data do not confirm the appearance of most lineages of “crown Acanthomorpha” (and even “crown Percomorpha”) already at the end of the Cretaceous, as indicated by the time-calibrated molecular phylogeny.

Temperature, species identity and morphological traits predict carbonate excretion and mineralogy in tropical reef fishes

Anthropogenic pressures are restructuring coral reefs globally. Sound predictions of the expected changes in key reef functions require adequate knowledge of their drivers. Here we investigate the determinants of a poorly-studied yet relevant biogeochemical function sustained by marine bony fishes: the excretion of intestinal carbonates. Compiling carbonate excretion rates and mineralogical composition from 382 individual coral reef fishes (85 species and 35 families), we identify the environmental factors and fish traits that predict them. We find that body mass and relative intestinal length (RIL) are the strongest predictors of carbonate excretion. Larger fishes and those with longer intestines excrete disproportionately less carbonate per unit mass than smaller fishes and those with shorter intestines. The mineralogical composition of excreted carbonates is highly conserved within families, but also controlled by RIL and temperature. These results fundamentally advance our understanding of the role of fishes in inorganic carbon cycling and how this contribution will change as community composition shifts under increasing anthropogenic pressures.

Melatonin modulates the hypothalamic-pituitary neuroendocrine axis to regulate physiological color change in teleost fish.

Melatonin (MT) is a crucial neuroendocrine regulator of various physiological activities in vertebrates, especially in circadian or seasonal rhythm control. In the present study, the large yellow croaker (Larimichthys crocea), a marine bony fish with circadian body color change behavior, is chosen for functional investigation on teleost MT signaling systems that remain uncharacterized. All five melatonin receptors (LcMtnr1a1, LcMtnr1a2, LcMtnr1b1, LcMtnr1b2, and LcMtnr1c) were significantly activated by MT, triggering extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation through different G protein coupling signaling pathways, with exclusive Gαi-dependency for LcMtnr1a2 and LcMtnr1c, and Gαq-dependency for two LcMtnr1b paralogs, whereas LcMtnr1a1 activated Gαi and Gαs dual-dependent signaling pathways. A comprehensive model of the MT signaling system in the hypothalamic-pituitary neuroendocrine axis was further constructed based on ligand-receptor interaction analysis using single-cell RNA-seq data, as well as spatial expression patterns of Mtnrs and related neuropeptides in central neuroendocrine tissues. A novel regulatory pathway of MT/melanin-concentrating hormone (MCH) and MT/(tachykinin precursor 1 (TAC1)+corticotropin-releasing hormone (CRH))/melanocyte-stimulating hormone (MSH) was discovered that functions in chromatophore mobilization and physiological color change and was further validated by pharmacological experiments. Together, our findings define multiple intracellular signaling pathways mediated by L. crocea melatonin receptors and provide the first in-depth evidence that uncover the upstream modulating roles of the MT signaling system in the hypothalamic-pituitary neuroendocrine axis of a marine teleost species, particularly in chromatophore mobilization and physiological color change.

12S gene metabarcoding with DNA standard quantifies marine bony fish environmental DNA, identifies threshold for reproducible detection, and overcomes distortion due to amplification of non‐fish DNA

AbstractSingle‐species PCR assays accurately measure eDNA concentration. Here we test whether multi‐species PCR, that is, metabarcoding, with an internal standard can quantify eDNA of marine bony fish. Replicate amplifications with Riaz 12 S gene primers were spiked with known amounts of a non‐fish vertebrate DNA standard, indexed separately, and sequenced on an Illumina MiSeq. Fish eDNA copies were calculated by comparing fish and standard reads. Relative reads were directly proportional to relative DNA copies, with average and maximum variance between replicates of about 1.3‐ and 2‐fold, respectively. There was an apparent minimum threshold for consistent amplification of about 10 eDNA copies per PCR reaction. The internal DNA standard corrected for suppression of fish read counts due to amplification of non‐fish DNA. To assess potential PCR bias among species, we compared reads obtained with Riaz 12 S primers to those with modified MiFish primers, which target a different 12 S gene segment. Our results provide evidence that Riaz 12 S gene metabarcoding with an internal DNA standard quantifies marine bony fish eDNA over a range of about 10–5000 copies per reaction, without indication of significant PCR bias among teleost species. In mid‐Atlantic coastal samples, eDNA rarity was the main limitation to reproducible detection and quantification, and this was partly overcome by increasing the amount of a DNA sample amplified. Our findings support incorporating a DNA standard in 12 S metabarcoding to help quantify eDNA abundance for marine bony fish species.

Distribution of the Order Lampriformes in the Mediterranean Sea with Notes on Their Biology, Morphology, and Taxonomy.

Simple SummaryThe distribution of teleost fishes is of fundamental importance to comprehending how these species contribute to the ecological equilibria of marine areas. In these terms, fishes of the order Lampriformes are circumglobally distributed, and are characterized by a peculiar morphology. Information on this fish group is scarce to absent regarding both their biological and distribution features, especially for the Mediterranean Sea. Moreover, the systematics of the group underwent several rearrangements, and molecular support is still scarce. This review aimed to describe the biological and ecological characteristics of the order Lampriformes, and to compile the scattered Lampriformes records from the literature. Lampriformes represent a taxon of high biological and ecological importance whose knowledge is limited by their low commercial value and rarity. The bathymetrical range of distribution also makes these species very interesting from an adaptive point of view. Four families are present in the Mediterranean Sea—Lampridae, Lophotidae, Regalecidae, and Trachipteridae—with a total of six species. Despite the scarce information on this taxon, the present review, which collected all reports of the Mediterranean Sea, represents a baseline to increase the knowledge of these rare and important species, and to encourage new studies in this area. Moreover, a phylogenetic reconstruction of Lampriformes based on the cytochrome oxidase subunit 1 (mt-COI) gene sequences questions the current evolutionary relationships between some species.Lampriformes are circumglobally distributed and contain several families of strictly marine bony fishes that have a peculiar morphology. Lampriformes systematics is affected by limitations in biometric, meristic, and molecular data; for this reason, it underwent several rearrangements in the past. This review aimed to describe the biological and ecological characteristics of the order Lampriformes, summarizing the current taxonomy of the group. The main aim was to clarify what is known about the distribution of the order Lampriformes in the Mediterranean Sea, collecting all the scarce and fragmented reports and notes on their occurrence. Knowledge scarcity is due to their solitary nature, in addition to their low to absent economic value. Despite this, the order Lampriformes represents a taxon of high biological and ecological importance. The high depth range of distribution characterizes their lifestyle. In the Mediterranean Sea, four families are present—Lampridae, Lophotidae, Regalecidae, and Trachipteridae—with the following species respectively, Lampris guttatus (Brünnich, 1788), Lophotus lacepede (Giorna, 1809), Regalecus glesne (Ascanius, 1772), Trachipterus arcticus (Brünnich, 1788), T. trachypterus (Gmelin, 1789), and Zu cristatus (Bonelli, 1819). Data deficiencies affect information on this taxon; the present review, which collected all the reports of the Mediterranean Sea, creates a baseline for depicting the biogeography of these rare and important species.

Assessment of conservations actions for the critically endangered spotted handfish (Brachionichthyidae), following curation of data collected by multiple investigators into a long-term time-series

Multi-decadal datasets for endangered species that track both populations and performance of management interventions are rare. One such dataset is for the critically endangered Spotted handfish, a species which has been used as a conservation model for the most endangered of the marine bony fish families the Brachionichthyidae. We assessed a 23-year, multi-site, time-series of population density surveys for the spotted handfish as well as a conservation intervention, the planting of ∼ 14,000 artificial spawning habitats (ASH). Data ownership spanned multiple Principal Investigators (PIs) and key data and covariates, such as monitoring and interventions, were often documented within personal files and difficult to access grey literature. We consolidated and curated these data, identifying gaps in the time-series and their causes and isolating confounding factors before we assessed population trends and the effectiveness of ASH planting. Both funding gaps and the 2020 Covid-19 lockdown produced breaks in the time-series. Breeding season observations mostly occurred in the early part of the dataset and there was also a change in method that needed to be considered when interpretating the time-series. There was an overall decline in fish observed between 1997 and 2019 but, at least since 2014, there has been stabilisation of the population. Local populations of spotted handfish can either be highly dynamic or relatively stable but population increases were linked to the long-running, conservation intervention of planting ASH. As local populations can be dynamic, the functional life span of the ASH is limited and threats to the species - chronic, stochastic and climate - are ongoing, spotted handfish may be a ‘conservation reliant’ species that require annual site-specific monitoring, insitu interventions and existu captive husbandry.

Description of Gyrodactylus paludinosus sp. nov. (Monogenea: Gyrodactylidae) from the Straightfin Barb, Enteromius paludinosus (Peters, 1852), in South Africa.

Parasites of the genus Gyrodactylus von Nordmann, 1832, are predominantly parasites of freshwater and marine bony fishes. To date, 40 species of the genus have been described from Africa, with only 6 of these reported from South Africa. This represents only a small fraction of the known diversity of almost 500 species known worldwide. In total, 43 of Straighhfin barb, Enteromius paludinosus were collected from Barberspan Bird Sanctuary, North West Province, South Africa. Monogenean parasites were isolated from the fins and fixed on microscope slides in ammonium picrate glycerine. Morphometric evaluation of opisthaptoral hard parts confirmed the identity of these specimens as a new species. The description of Gyrodactylus paludinosus sp. nov. is presented. The new species has well-developed, slightly curved superficial inner roots and well-developed rectangular-like ventral bar membrane. Despite the small differences between the hamuli size, it can be distinguished from its congeners, G. kyogae and G. ivindoensis, the only species known from small African barbs, by the shape of ventral bars and marginal hook sickle propers. The description of Gyrodactylus paludinosus n. sp. increases the total number of Gyrodactylus spp. known from African cyprinid fish to three. Undoubtedly, more attention should be given to studies on small barbs as potential hosts for new species.

Fish otoliths from the early Miocene of Chile: a window into the evolution of marine bony fishes in the Southeast Pacific

Few fossil fish otolith associations have been described from the Pacific side of the Americas and, except for a single species (Steindachneria svennielseni), none have been described from Pacific South America south of the Central American tropical region. Here, we describe a rich otolith assemblage obtained from fifteen early Miocene outcrop locations along the Chilean coast from about 33°S to about 45°S. More than 2,000 specimens were studied resulting in the recognition of 67 species, with 27 being new to science. This assemblage represents an important new data point distant from any previously known otolith-based fish fauna, with the nearest coeval associations being from the Caribbean Province in Venezuela, which lies about 5000 km to the north, and New Zealand, which is about 9000 km to the west. The fauna represents a mixture of offshore and shallow water fishes and is rich in myctophids, paralichthyids (Citharichthys), ophidiids (Lepophidium), steindachneriids, and macrourids. Typical tropical American fishes are nearly completely absent, with the exception of Steindachneria and certain anguilliforms. The mesopelagic faunal component, chiefly Myctophidae, shows a striking resemblance to the well-known coeval fish fauna from New Zealand, and both are interpreted as representing an early South Pacific mesopelagic bioprovince. The strong correlation with the mesopelagic otolith-based fish fauna from New Zealand constricts the time interval of the sampled sediments to the middle Burdigalian (approximately 17.5 to 18.5 Ma). All otoliths obtained from the early Miocene of Chile relate to extant fish groups of the area and few exotic components not currently present in the East Pacific. The sole exception is a morpho-type described as Navidadichthys which has an unresolved relationship, possibly with the Prototroctidae, a family that is today endemic to the freshwater and nearshore marine environments of Australia and New Zealand. The new taxa are in the sequence of taxonomic description: Pterothrissus transpacificus n. sp., Pythonichthys panulus n. sp., Chiloconger chilensis n. sp., Gnathophis quinzoi n.sp., Rhynchoconger chiloensis n. sp., Navidadichthys mirus n. gen. et n. sp., Maurolicus brevirostris n. sp., Polyipnus bandeli n. sp., Lampanyctus ipunensis n. sp., Physiculus pichi n. sp., Coelorinchus fidelis n. sp., Coelorinchus rapelanus n. sp., Nezumia epuge n. sp., Paracarapus chilensis n. gen. et n. sp., Lepophidium chonorum n. sp., Lepophidium mapucheorum n. sp., Sirembola supersa n. sp., Spectrunculus sparsus n. sp., Pseudonus humilis n. sp., Capromimus undulatus n. sp., Agonopsis cume n. sp., Cottunculus primaevus n. sp., Kuhlia orientalis n. sp., Citharichthys parvisulcus n. sp., Citharichthys vergens n. sp., Achirus australis n. sp., Achirus chungkuz n. sp.

A Hiatus Obscures the Early Evolution of Modern Lineages of Bony Fishes

About half of all vertebrate species today are ray-finned fishes (Actinopterygii), and nearly all of them belong to the Neopterygii (modern ray-fins). The oldest unequivocal neopterygian fossils are known from the Early Triassic. They appear during a time when global fish faunas consisted of mostly cosmopolitan taxa, and contemporary bony fishes belonged mainly to non-neopterygian (“paleopterygian”) lineages. In the Middle Triassic (Pelsonian substage and later), less than 10 myrs (million years) after the Permian-Triassic boundary mass extinction event (PTBME), neopterygians were already species-rich and trophically diverse, and bony fish faunas were more regionally differentiated compared to the Early Triassic. Still little is known about the early evolution of neopterygians leading up to this first diversity peak. A major factor limiting our understanding of this “Triassic revolution” is an interval marked by a very poor fossil record, overlapping with the Spathian (late Olenekian, Early Triassic), Aegean (Early Anisian, Middle Triassic), and Bithynian (early Middle Anisian) substages. Here, I review the fossil record of Early and Middle Triassic marine bony fishes (Actinistia and Actinopterygii) at the substage-level in order to evaluate the impact of this hiatus–named herein the Spathian–Bithynian gap (SBG)–on our understanding of their diversification after the largest mass extinction event of the past. I propose three hypotheses: 1) the SSBE hypothesis, suggesting that most of the Middle Triassic diversity appeared in the aftermath of the Smithian-Spathian boundary extinction (SSBE; ∼2 myrs after the PTBME), 2) the Pelsonian explosion hypothesis, which states that most of the Middle Triassic ichthyodiversity is the result of a radiation event in the Pelsonian, and 3) the gradual replacement hypothesis, i.e. that the faunal turnover during the SBG was steady and bony fishes were not affected by extinction events subsequent to the PTBME. Based on current knowledge, hypothesis three is favored herein, but further studies are necessary to test alternative hypotheses. In light of the SBG, claims of a protracted diversification of bony fishes after the PTBME should be treated with caution.

Genetic diversity and restricted genetic connectivity in an endangered marine fish (

Determining the genetic diversity and differentiation among populations is a critical element of conservation biology, but for many aquatic, data-deficient species with small population sizes, this is not possible. Closely related species may therefore provide a model. For the first time, using over 4000 single-nucleotide polymorphism loci, we characterise the population genetic diversity and structure of one of the world’s rarest marine fish, the spotted handfish (Brachionichthys hirsutus), a species which is also a member of the most threatened marine bony fish family (Brachionichthyidae). Fin clips were taken from 170 live spotted handfish across seven disjunct sites within the only known estuary (in Tasmania, Australia) where multiple populations of the species are found. Spatially discrete populations clustered into three genetic groupings and a significant variance in allele frequencies among populations (overall FST = 0.043), even at the small scale of the estuary, was observed. Furthermore, low contemporary migration rate estimates suggest low genetic homogeneity between locations. Because of the low genetic connectivity, population clusters of spotted handfish within the estuary should be considered as separate conservation management units. This insight should be considered for management and conservation strategies of other data-deficient and threatened species in the family.

Conservation challenges for the most threatened family of marine bony fishes (handfishes: Brachionichthyidae)

Marine species live out-of-sight, consequently geographic range, population size and long-term trends are extremely difficult to characterise for accurate conservation status assessments. Detection challenges have precluded listing of marine bony fishes as Extinct on the International Union for Conservation of Nature (IUCN) Red List, until now (March 2020). Our data compilation on handfishes (Family Brachionichthyidae) revealed them as the most threatened marine bony fish family, with 7 of 14 species recently listed as Critically Endangered or Endangered. The family also includes the only exclusively marine bony fish to be recognised as Extinct – the Smooth handfish (Sympterichthys unipennis). Ironically, some of the characteristics that threaten handfishes with extinction have assisted assessments. Poor dispersal capabilities leading to small, fragmented populations allow monitoring and population size estimation for some shallow water species. Evidence that the Smooth handfish is now Extinct included no sightings over 200 years in an area subject to numerous scientific surveys, inferred shallow habitat and moderate abundance at time of original collection, and major habitat transformation through fishing, aquaculture, rising sea temperature, and urban development. Contemporary threats to extant handfish species include habitat degradation, introduced species, loss of spawning substrate, climate change, and demographic risks associated with small, fragmented populations. Multifaceted conservation efforts are needed, including addressing threats to habitat quality, bolstering wild population numbers, and implementing novel techniques to find and monitor populations. Expanded monitoring, including application of eDNA methods, represent critical steps towards overcoming the challenges in studying wild populations of rare marine species. Ongoing investigation will likely reveal numerous other threatened species for which little is known.

Eye lens Δ14C validates otolith-derived age estimates of Gulf of Mexico reef fishes

We tested whether Δ14C values of eye lens protein (crystallin) formed in early life could be utilized to validate marine bony fish age estimates via the bomb radiocarbon chronometer. The slope of the relationship between red snapper (Lutjanus campechanus; n = 8; 0 to 27 years old), otolith and eye lens core Δ14C values was not significantly different than 1, which was also true for seven additional reef fish species (n = 21; 0 to 24 years old). Results demonstrate eye lens core Δ14C can be utilized to validate age estimates of marine fishes, which will be useful in numerous age validation applications.

Two-step extinction of Late Cretaceous marine vertebrates in northern Gulf of Mexico prolonged biodiversity loss prior to the Chicxulub impact

Recent studies on mass extinctions are often based on the global fossil record, but data from selected paleogeographic regions under a relatively constant paleoenvironmental setting can also provide important information. Eighty-nine marine vertebrate species, including cartilaginous and bony fish and marine reptiles, from northern Gulf of Mexico – located about 500 km from the Chicxulub crater – offer a unique opportunity to determine an extinction process during the last 20 million years of the Late Cretaceous. Our diversity data show two separate extinction events: (i) the ‘Middle Campanian Crisis’ (about 77 Mya) and (ii) the end-Maastrichtian (66 Mya) events. Whether this stepwise pattern of extinctions occurred locally or globally cannot be determined at present due to the lack of a dataset of the marine vertebrate record for reliable comparison. However, this stepwise pattern including the Middle Campanian and end-Maastrichtian events for, at least, a 13 million-year interval indicates long-term global marine environmental changes (e.g., regression, ocean water chemistry change). Because most Cretaceous marine vertebrates already disappeared in the Gulf of Mexico prior to the latest Maastrichtian, the Chicxulub Impact may not be considered as the most devastating extinction event for the community.

Regional extinction risks for marine bony fishes occurring in the Persian/Arabian Gulf

The Persian/Arabian Gulf (hereafter, ‘the Gulf’) is an environmentally extreme sea that is being increasingly affected by climate change and anthropogenic stressors, and concern is growing about the future of marine biodiversity in the region. However, identification of species and habitats most in need of conservation is challenging as comprehensive information on species-specific threats and population statuses is lacking. Through application of the International Union for Conservation of Nature (IUCN) Red List methodology – the global accepted standard for classifying extinction risk at the species level – we evaluated the regional conservation status of 471 species of marine bony fishes in the Gulf. The best estimate of the proportion of regionally threatened marine bony fishes, based on all species for which sufficient data were available for assessment, is 8.2%; this is at least twice the proportion of other regions where such assessments have been undertaken. Primary threats include those related to fisheries and harvesting and those related to coastal development and loss of habitat, impacting 47% and 32% of marine bony fishes, respectively. Such threats are particularly acute in nearshore areas where spatial analyses indicated high species richness. The future of Gulf ecosystems, and the survival of the marine bony fishes, will depend on concerted, collaborative efforts among all Gulf States to develop efficient and effective local and regional marine conservation practices and policies, particularly for species assessed as regionally threatened.

Reef fish carbonate production assessments highlight regional variation in sedimentary significance

Recent studies show that all marine bony fish produce mud-sized (<63 mu m) carbonate at rates relevant to carbonate sediment budgets, thus adding to the debate about the often enigmatic origins of fine-grained marine carbonates. However, existing production data are geographically and taxonomically limited, and because different fish families are now known to produce different carbonate polymorphsan issue relevant to predicting their preservation potential-these limitations represent an important knowledge gap. Here we present new data from sites in the Western Pacific Ocean, based on an analysis of 45 fish species. Our data show that previously reported production outputs (in terms of rates and family-specific mineralogies) are applicable across different biogeographic regions. On this basis, we model carbonate production for nine coral reef systems around Australia, with production rates averaging 2.1-9.6 g m(-2) yr(-1), and up to 105 g m(-2) yr(-1) at discrete sites with high fish biomass. With projected production rates on lower-latitude reefs up to two-fold higher, these outputs indicate that carbonate production rates by fish can be comparable with other fine-grained carbonate-producing taxa such as codiacean algae. However, carbonates produced by Australian reef fish assemblages are dominated by a highly unstable amorphous polymorph; a marked contrast to Caribbean assemblages in which Mg calcite dominates. These findings highlight important regional differences in the sedimentary relevance and preservation potential of fish carbonates as a function of historical biogeographic processes that have shaped the world's marine fish faunas.

Interrogation of the Gulf toadfish intestinal proteome response to hypersalinity exposure provides insights into osmoregulatory mechanisms and regulation of carbonate mineral precipitation

Marine bony fish live in a hyperosmotic environment and maintain osmotic homeostasis by drinking seawater, and absorbing salt and water across their gastrointestinal tract. Although the ion and water transport mechanisms in the intestine have been the subject of much study, numerous questions remain unanswered. To address some of these questions, a shotgun proteomics methodology employing isobaric tandem mass tags (TMT) was used to interrogate the anterior intestine, posterior intestine, and intestinal fluid proteomes of Gulf toadfish (Opsanus beta) acclimated to normal (35 ppt) or hypersaline (60 ppt) seawater. Relative protein abundance between tissues was also investigated using label free quantitation. Protein products from nearly 3000 unique toadfish loci were identified and quantified between the tissues, and pathway analysis was performed to gain insight into biological significance. Numerous proteins potentially involved in ion transport, digestion, nutrient absorption, and intestinal CaCO3 precipitation were found to respond to changing salinity, providing additional insight into the molecular mechanisms behind these processes. Intestinal protein heterogeneity was also observed with proteins involved in ion transport responding to hypersalinity exposure primarily in the anterior intestine, and proteins involved in digestion and nutrient absorption showing higher abundance in the anterior intestine, regardless of salinity.

Complete mitochondrial genome of the larval Syngnathus schlegeli (Gasterosteiformes, Syngnathidae) from Yangtze estuary and the phylogenetic relationship of genus Syngnathus

The complete mitochondrial genome of the larval Syngnathus schlegeli collected from Yangtze estuary was determined by next-generation sequencing. The mitogenome is a circular molecule 16,465 bp in length, including 13 protein-coding genes, two ribosomal RNA genes, 22 transfer RNA genes, and a control region. The TAS, central CSB and CSB were detected in the control region. The gene contents of the mitogenome are identical to those observed in most marine bony fishes. The NJ phylogenetic tree showed that S. schlegeli clustered in a branch close to the species from the same genus.