Reviews in Fish Biology and Fisheries最新文献

In recent years, the environmental pollution caused by microplastics (MPs) has attracted extensive attention. Numerous studies have shown that MPs could cause liver damage in aquatic animals. However, there is a limited range of technical approaches available to mitigate and minimize the detrimental impact of MPs on both wild fish populations and aquaculture operations. Thus, this study aimed to investigate the impact of dietary chitosan supplementation on the prevention and treatment of liver damage induced by exposure to polystyrene microplastics (PS-MPs) in Nile tilapia (Oreochromis niloticus). The results indicated that after two weeks of exposure, the liver of tilapia showed oxidative stress, inflammatory response and fibrosis. Meanwhile, after the chitosan addition, the oxidative stress, inflammatory response and fibrosis of tilapia liver were reversed, the pyroptosis and ferroptosis in tilapia liver were inhibited, the combination of mitochondria with PS-MPs in tilapia liver cells was inhibited, and the mitochondrial damage was reversed. In summary, the study confirmed the potential prophylaxis and treatment effect of dietary chitosan supplementation on PS-MPs exposure-induced liver damage in tilapia, and provided basic data for further studies on prophylaxis and treatment of the toxic effects of MPs. This study also presented efficacious strategies for alleviating the deleterious impacts of MPs on fish farming, thereby fostering sustainable and eco-friendly approaches in aquaculture.

Graphical abstract

Global ocean warming and extreme climate events pose a severe threat to marine biodiversity by inducing species redistribution and ecosystem reorganization. It is important to quantify the impacts of marine heatwaves (MHWs) on marine cetacean habitats to avoid rapid ecosystem shifts. Here we utilized detected breakpoints and early warning indicators derived from sightings data spanning from 2009 to 2021 to assess the distribution change of Indo-Pacific humpback dolphin (Sousa chinensis). We found that (1) during the 2014 MHWs, the encounter rates (number of on-effort sightings per 100 km) of humpback dolphins in Hong Kong waters significantly decreased, with the breakpoint occurring during the autumn of 2014; (2) Since 2014, Hong Kong waters have experienced more prolonged and frequent MHWs, with a significant reduction of core habitat by 26%; according to Granger causality analysis, changes in sea surface temperature drove shifts in dolphin distribution; (3) Our analysis revealed a co-existence of rapid annual increases in MHWs and high habitat usage, with the marine park located in Southwest Lantau being particularly at risk. This study on dolphin distribution shifts and their relationships with marine heatwaves in Southern China made a contribution to our understanding of the action of marine cetaceans' response to climate change. Additionally, it highlights the importance of considering MHWs in dolphin conservation efforts.

Fish biologists have long assumed a link between intestinal length and diet, and relative gut length or Zihler’s index are often used to classify species into trophic groups. This has been done for specific fish taxa or specific ecosystems, but not for a global fish dataset. Here, we assess these relationships across a dataset of 468 fish species (254 marine, 191 freshwater, and 23 that occupy both habitats) in relation to body mass and fish length. Herbivores had significantly relatively stouter bodies and longer intestines than omni- and faunivores. Among faunivores, corallivores had longer intestines than invertivores, with piscivores having the shortest. There were no detectable differences between herbivore groups, possibly due to insufficient understanding of herbivorous fish diets. We propose that reasons for long intestines in fish include (i) difficult-to-digest items that require a symbiotic microbiome, and (ii) the dilution of easily digestible compounds with indigestible material (e.g., sand, wood, exoskeleton). Intestinal indices differed significantly between dietary groups, but there was substantial group overlap. Counter-intuitively, in the largest dataset, marine species had significantly shorter intestines than freshwater fish. These results put fish together with mammals as vertebrate taxa with clear convergence in intestine length in association with trophic level, in contrast to reptiles and birds, even if the peculiar feeding ecology of herbivorous fish is probably more varied than that of mammalian herbivores.

Omega-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFA) are essential fatty acids required in healthy balanced diets for humans. To induce sustained production of n-3 LC-PUFA in gilthead seabream (Sparus aurata), chitosan-tripolyphosphate (TPP) nanoparticles encapsulating plasmids expressing fish codon-optimised Caenorhabditis elegans FAT-1 and FAT-2 were intraperitoneally administered every 4 weeks (3 doses in total, each of 10 μg plasmid per g of body weight). Growth performance and metabolic effects of chitosan-TPP complexed with pSG5 (empty plasmid), pSG5-FAT-1, pSG5-FAT-2 and pSG5-FAT-1 + pSG5-FAT-2 were assessed 70 days post-treatment. Tissue distribution analysis showed high expression levels of fish codon-optimised FAT-1 and FAT-2 in the liver (> 200-fold). Expression of fat-1 and fat-1 + fat-2 increased weight gain. Fatty acid methyl esters assay revealed that co-expression of fat-1 and fat-2 increased liver production and muscle accumulation of eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and total n-3 LC-PUFA, while decreased the n-6/n-3 ratio. Co-expression of fat-1 and fat-2 downregulated srebf1 and genes encoding rate-limiting enzymes for de novo lipogenesis in the liver, leading to decreased circulating triglycerides and cholesterol. In contrast, FAT-2 and FAT-1 + FAT-2 upregulated hepatic hnf4a, nr1h3 and key enzymes in glycolysis and the pentose phosphate pathway. Our findings demonstrate for the first time efficient and sustained production of EPA and DHA in animals after long-term treatment with chitosan-TPP-DNA nanoparticles expressing FAT-1 and FAT-2, which enabled the production of functional fish rich in n-3 LC-PUFA for human consumption.

A global analysis of the functional characteristics of meta-assemblages of estuary-associated fishes was undertaken at the marine ecoregion level. Marine ecoregions were grouped into broad biogeographic regions (bioregions) and functional attributes of the fish assemblages compared based on a numerical fish estuary association score, as well as estuarine use functional groups. Relationships between selected environmental characteristics and fish functional attributes were also examined. A significant relationship between ecoregion environmental variables and estuarine fish functional assemblages was recorded, with the key environmental factors identified being related to habitat (estuarine area and macrophyte vegetation), connectivity (mean annual runoff), and physico-chemical (sea surface temperature and sea surface salinity) variables.

Abandoned, lost, and discarded fishing gear (ALDFG) is a problem that is increasingly of concern to global fisheries resources and the aquatic environment. Nearly 2% of all fishing gear used in marine fisheries is lost to the ocean annually. This has negative impacts on the aquatic ecosystem, which includes but not limited to ghostfishing mortality to commercial, recreational and protected species, degradation of benthic habitat, and change to the ecosystem. Fishing gear left in the sea can drift ashore affecting recreational use of beaches and shorelines and poses hazards to navigation. Most of the research on ALDFG has been in the marine fisheries of the developed world with very few studies in the inland fisheries, mostly in the developing world of sub-Saharan Africa and Asia. This paper reviews and synthesizes literature about the status of ALDFG in inland fisheries globally. Only 16 studies, between 1970 to 2023, that referenced ALDFG causes, levels, impacts, and preventive measures were found. Thus, this review highlights that ALDFG in inland fisheries remains a highly understudied area of aquatic plastic pollution. Further studies are recommended to fully understand its status, extent, and potential environmental impacts.

Wave climate is shifting over the last decades along the Atlantic coasts of Europe ultimately driven by large-scale patterns of atmospheric variability forced by anthropogenic global warming. Changes in wave height and surf zone orbital currents are hypothesized to drive marked shifts in the shape of intertidal organisms such as the stalked barnacle Pollicipes pollicipes, whose quality and market price are known to decrease non linearly with the peduncle length: width ratio S. This study evaluates wave trends in NW Iberian Peninsula, using the Spanish Port System 2006–2020 SIMAR wave hindcast. On the other hand, trends in stalked barnacle morphology and quality are estimated from 26 sites at the management regions of Baiona and A Guarda between 2011 and 2020. Results show evidence of temporal changes in barnacle quality and, especially, morphometry caused by simultaneous shifts in winter wave induced orbital currents. Because of the non linear relationship between S and the high quality threshold, large increases in S are usually translated to small reductions in quality. However, we identified a tipping point around S = 2.4 that if surpassed can lead to great drops in barnacle quality. In addition, changes in wave forcing will have different effects at each extraction site, as trends in wave climate are decoupled from barnacle morphometry at steeper sites sheltered from the predominant wave direction. In conclusion, this knowledge could be applied to develop site specific barnacle harvesting strategies based on annual wave climate forecasts.

Graphical abstract

An assessment on the fluctuations in abundance of the striped venus clam (Chamelea gallina) in the southern Adriatic Sea (Central Mediterranean Sea), and the northern Gargano area, has been conducted through both historical information and recent data from monitoring surveys during the period 1997–2019. Production trends, conditions of the commercial stock biomass, and depth distribution pattern of juveniles and commercial sizes were analysed testing temporal differences. Moreover, the exploitation of the clam beds and recruitment events were investigated in 2018–2019. Changes in abundance were analysed using non-parametric tests for both juvenile (length class, LC < 22 mm) and commercial (LC ≥ 22 mm) fractions. Hydrodynamic changes, temperature and salinity variations were explored using a 3D hydrodynamic numerical model (MIKE 3 FM-HD) and statistical analysis, as well as changes in benthic assemblages impacted by hydraulic dredges were investigated through PERMANOVA and other multivariate analysis.

The results showed a temporal decline of production and biomass of C. gallina during the 1997–2019 period, and a regression of the depth limit in the clams’ distribution towards shallower waters. A significant reduction in juveniles was observed during 2018–2019 with a very limited recruitment. The fishing exploitation showed high impacts on the commercial stock and benthic assemblages in the summer of 2018. Overall, water currents were predominantly directed offshore in 2018, during the C. gallina spawning period. This could affect the larval dispersal and settlement on unsuitable bottoms. Anomalies in temperature (high peaks in August 2018, > 28 °C) and salinity (low values in spring 2018, < 37 PSU) could have induced stress and mortality events on the entire clam bed in the study area. This first study highlights the need to integrate environmental information in the assessment of commercial stocks of clams in the Adriatic Sea, to better understand climate change effects on the fluctuations and to support effective ecosystem-based fishery management.

Abstract

American shad (Alosa sapidissima) are an anadromous fish species native to North America that have an extensive range, but their populations are declining. Acoustic telemetry can play a vital role in better understanding the behavior and survival of this sensitive species, but successfully handling and tagging juvenile American shad can be challenging. We conducted several experiments to determine the best methods for collecting, transporting, holding, and tagging juvenile shad. Minimizing out-of-water handling and the use of a saltwater treatment during collection increased 24 h survival from 78 to 99% after transport. Saltwater was also fundamental in keeping tagged shad alive overnight. Shad as small as 50 mm, were implanted with a dummy acoustic transmitter using a pectoral incision method with no suture. In a 60 d holding evaluation, the tagged fish survived at a rate comparable to their non-tagged counterparts (81.5% for tagged, 70% for untagged). Tagged and untagged shad also had similar survival when exposed to a tank of predators. The results are important for improving conservation efforts for small, sensitive species of fish, like American shad.

Significant progress in our knowledge of Beringian biodiversity and in the technologies available for biodiversity research has been made in the several decades since a comprehensive biogeographic synthesis of Beringian freshwater fishes was compiled and published in 1986. Further, the fish fauna of Beringia and, more broadly, of high latitude freshwater systems of the northern hemisphere face some of the most intense well documented effects of global climate change. Here we synthesize current understanding of how the dynamic spatial and ecological landscapes of Pleistocene glaciations have shaped the distribution of taxonomic and genetic diversity in fish faunas of Beringia. Through a more complete integration of knowledge obtained in studies of fishes in Russian drainages, we aimed to identify promising strategies to test alternative biogeographic hypotheses on the roles played by the Bering land bridge, paleorivers and glacial history in intercontinental faunal movement. We focus on freshwater fishes of the Bering Strait region, which live in an environment that is premised on extreme instability and profound changes in long-term connectivity for fishes and offers opportunities to assess long-term evolutionary trends in both speciation and life history variation. Such information is critical for both our scientific understanding of evolutionary processes in fishes and valuable for those tasked with the challenges of management and conservation of natural resources in this expansive, dynamic and remote region. We provide an overview of Beringian freshwater ichthyofauna and examine genetic differentiation among population units within these lineages. We also examine evidence for how long population units have been separated based on historic glacially-related separations and the more recent marine barrier of the Bering Strait that constrains freshwater or diadromous species based on their ability to disperse in salt water. Our review concludes on how Arctic and sub-Arctic fishes may adapt and persist in their dynamic environment considering low genetic diversity, the role of adaptive introgression, and epigenetic variation. We find that Beringian fishes may poorly fit traditional taxonomic categories and the designation of conservation units below the species level may be of great practical application. Furthermore, as hybridization is documented to increase in the Arctic, the use of this process for ecological monitoring may also be of high utility with Beringian fishes.