Environmental Biology of Fishes最新文献

Contamination by microplastics (MPs) has been recorded in various environments and organisms around the world. The objective of this study was to investigate the occurrence of MPs in two species of Siluriformes fishes Pterygoplichthys pardalis and Hoplosternum littorale considering the sex and different body parts of fish captured in Amazon floodplain areas, which are marketed and consumed in the Municipality of Itacoatiara, Amazonas, Brazil. One hundred and fifty individuals of each fish species were analyzed for microplastics. Of these, 252 individuals were found to contain MPs: 127 (85%) P. pardalis and 125 (83%) H. littorale. The fish were contaminated with 683 MP particles, ranging from 1 to 43 MP particles/individual, with an average of 2.71 ± 3.2 MP particles/individual P. pardalis and H. littorale. Comparison of MP occurrence and particle size between species, sex, and body part found no significant difference. Fiber-shaped and blue-colored MPs were the most abundant in both P. pardalis (80% and 85.5%, respectively) and H. littorale (92% and 85%, respectively). The particles were identified as polyethylene terephthalate and polystyrene. The results indicate MP contamination in P. pardalis and H. littorale catfish, which are widely consumed by Amazonian riverside communities. These species are often cooked whole (including the viscera) becoming a direct route of microplastic contamination to humans.

Anthropogenic pollutants are an ongoing problem in aquatic environments. One such pollutant is fluoxetine, a selective serotonin reuptake inhibitor commonly known by the brand name Prozac. We still do not fully understand how such medical wastes affect aquatic organisms, specifically, how they affect traits that are important to the ecology and evolution of populations and species. We examined how chronic exposure to a field-relevant concentration of fluoxetine (440 ng/L) affects different behaviors in wild-caught Gambusia holbrooki. We tested fish social behavior, cognitive flexibility, and tendency to disperse in an artificial stream. We found that exposure to fluoxetine did not affect performance in any of the aforementioned behavioral assays. Furthermore, neither sociability nor cognitive flexibility predicted movement in the dispersal assay. At least for G. holbrooki, it appears that fluoxetine may not have large effects on the tested predictive behaviors or dispersal itself. While these results suggest that fluoxetine exposure may have limited effects on a key trait important in ecology and evolution—namely dispersal—it may still affect other traits not tested in this study.

Abstract

The sex ratio, size, age, growth, maturation, gonado-somatic index, and mortality of the Black Sea whiting Merlangius merlangus (Linnaeus, 1758) were studied. The ecological and geographical variabilities of its life-history traits were analyzed in terms of its compliance with the temperature-size rule (TSR). Overall, 1148 individuals were examined from 2019 to 2022. The sex ratio in catches was biased towards females (1:0.14). The maximum (total) length of the females was 36.4 cm; that of the males 21 cm; the corresponding weights and ages were 582 g and 7 years and 66.5 g and 4 years, respectively. The values of the Bertalanffy equation parameters were L_∞ = 30.8 cm, W_∞ = 207 g, and K = 0.16 year⁻¹ for females and L_∞ = 20.8 cm, W_∞ = 57.7 g, and K = 0.29 year⁻¹ for males, while the mean length at first maturity was 14.13 ± 0.13 cm for the females and 12.14 ± 0.06 cm for the males. The highest spawning activity was observed from January to March. The exploitation rate in females was E = F/Z = 0.67, indicating high fishing pressure. The Mediterranean and Black Sea whiting is characterized by smaller sizes and shorter lifespan than individuals in Northern, colder areas. Thus, its size, and lifespan are expected to decrease with climate warming.

Effective restoration of tidal wetlands for fish communities requires clear goals and mechanistic understanding of the ecosystem drivers which affect fish distribution and abundance. We examined fish community responses to abiotic habitat features in two adjacent but dissimilar freshwater tidal wetlands in the Sacramento-San Joaquin Delta, CA, USA, each of which represents a potential restoration configuration. The first wetland was characterized by a broad, intertidal basin with relatively high hydrodynamic exchange with surrounding waterways. The second wetland was characterized by a dendritic network of shallow subtidal channels with relatively low hydrodynamic exchange. Fish community composition significantly differed between the two wetlands, based on permutational analysis of variance. Fish abundance within and among the two wetlands was also highly affected by specific geomorphic and hydrodynamic characteristics: distance from connection with the main external waterway, bed elevation, and water surface elevation. The physical configuration of a restored tidal wetland, in conjunction with the way tides move across the restored landscape, has strong implications for local fishes. Manipulating these elements to create a landscape mosaic of habitat configurations can be an effective tool for targeting desired restoration outcomes, such as specific fish communities or target fish densities.

Arctic char (Salvelinus alpinus) and Dolly Varden (S. malma) are two closely related species in the genus Salvelinus. Both species show substantial intra-specific variation in ecology, morphology, and post-glacial history across their distributional ranges, which has presented substantial challenges for conservation and management and has led to the coining of the term, ‘the charr problem’. Arctic char and Dolly Varden have been studied extensively by scientists since the 1700s, not only because these fishes play important ecological roles within ecosystems, but also because they are culturally, economically, and recreationally valuable. While several detailed reviews have been published on Arctic char over the past 40 years, Dolly Varden remain understudied. In addition, advances in the fields of genetics, ecology, and morphometrics have improved our understanding of the behavior, feeding, habitat requirements, post-glacial histories and intraspecific diversity of each of these two species. Herein, we present an updated review that focuses on placing findings from more recently published (through 2022) phylogenetic, ecological and morphometric studies within the foundational context of earlier papers and reviews (since 1943). We also review anticipated effects of climate change on both species. Across their ranges, Arctic char and Dolly Varden can display a variety of life history types, with many populations exhibiting anadromy and/or potadromy; due to their use of distinct habitats at specific life stages, migratory chars are vulnerable to climate-induced changes to habitat quantity and quality. In addition to reviewing the existing literature, we highlight knowledge gaps and research priorities that, when addressed, will enable more informed conservation and management initiatives for these highly valued fishes.

Abstract

A mountain mass from which multiple river basins originate is a possible determinant of genetic structure of freshwater fishes. In this study, subspecies composition and genetic structure were examined for Japanese white-spotted char comprising of two subspecies, Salvelinus leucomaenis imbrius (Jordan and McGregor), “Gogi,” and S. l. pluvius (Hilgendorf), “Nikkoiwana,” collected in the 19 river basins originating from 6 mountain masses in the Chugoku Region, Japan, based on mitochondrial DNA sequences. In the western mountain masses, only Gogi was collected, while in the eastern mountain mass, only Nikkoiwana was collected. A total of 27 haplotypes were detected, among which only seven were shared by two subspecies and three were detected only in Nikkoiwana whereas 17 were detected only in Gogi. As many as 11 haplotypes were distributed only in the Oyorogi Mountain mass in the middle region. In the network, one group was exclusively constructed by the samples from the Oyorogi Mountain mass. Furthermore, in a tree of river basins based on average genetic distance of char, the Gono River basin originating from the Asa Mountain mass, situated in the western region, participated in a clade constructed by the rivers originating from the westernmost Sukegatake and the adjacent Asa Mountain masses, whereas the Gono River basin originating from the Oyorogi Mountain mass participated in a different clade constructed by the rivers originating from the Oyorogi to the easternmost Hyonosen Mountain masses. These results suggest that a mountain mass is a determinative factor to subspecies composition and genetic structure of char, with an implication of invasion of fish taking advantage of some geological events or conditions.

Water pollution imperils the Neosho madtom (Noturus placidus), which is threatened federally and in Kansas. Within Kansas, madtom densities were historically lower in the Spring River compared to the Cottonwood and Neosho Rivers, especially within the Spring River below tributary inputs that delivered cadmium, copper, lead, and zinc pollution from the Tri-State Mining District of Missouri, Kansas, and Oklahoma. Neosho madtom are less numerous in waters containing elevated metal concentrations because of direct toxicity and lower benthic macroinvertebrate (i.e., food) availability. Long-term reductions in metal concentrations in the Spring River have occurred, but no study has examined whether madtom and macroinvertebrate densities have responded to improved water quality. We addressed this question by comparing madtom and macroinvertebrate abundances between the Neosho-Cottonwood system and the Spring River above and below metal pollution inputs. However, madtoms are influenced by environmental factors and anthropogenic stressors beyond mining-derived metal pollution, so we also examined if food availability, local habitat variables, and watershed characteristics were related to madtom densities. We found that madtom and macroinvertebrate population densities in the Spring River below metal pollution were similar to those in the Spring River above metal pollution and the Neosho-Cottonwood River system. Furthermore, macroinvertebrate availability and watershed characteristics were not associated with madtom abundance. However, two local habitat variables (turbidity and depth) were associated with madtom densities, such that an increase in turbidity or decrease in depth resulted in higher madtom densities. Our results highlight the benefits that water quality improvements can have on imperiled stream organisms.