Search

Climate change may impact individual organisms in different ways, a consideration often overshadowed by predominant focus on population effects in studies. We examined three estuarine fish species to determine if individual fish performance, persisted across winter water temperatures. Fish performance at 16 °C (current Sydney winter estuarine water temperature) and 20 °C (predicted under climate change) with low and high food regimes was assessed using key physiological (growth, aerobic scope, burst speed) and behavioural parameters (foraging activity, boldness, shelter usage, predator escape response). We expected a strong positive relationship between performance at 16 °C and 20 °C for each parameter, and interactions with food level, however in general this was not found for any species. Relative performance was only maintained across temperatures for a few parameters, such as bite rate, boldness, and shelter response in one species (trumpeter Pelates sexlineatus), with aerobic scope in silver biddy Gerres subfasciatus, and boldness in fortescue Centropogon australis. Our results suggest that individuals' fitness (directly via changes in growth, indirectly via behaviours) might be impacted by climate warming due to differences in relative performance among juvenile individuals across water temperatures. Changes in relative performance among individuals may initially compensate for a population-level response, thereby buffering the effects of climate change. [ABSTRACT FROM AUTHOR]

This study investigated iron (Fe) accumulation in South Kalimantan's coastal swamp wetlands ecosystem, utilizing giant mudskipper fish as indicators of heavy metal pollution. By analyzing Fe levels in water, sediment, and fish organs over time, insights into its effects on the environment and human health were gained. Furthermore, through Atomic Absorption Spectrometry, Fe concentrations in Kuala Lupak's coastal wetland were measured, revealing significant correlations between Fe levels in water, sediment, and fish tissues. These results enhance our understanding and inform better management strategies. Anthropogenic and natural sources contribute to the accumulation of heavy metals, particularly Fe, with anthropogenic pollution being the most dominant. This study presented the escalating concentrations of Fe within the Kuala Lupak estuary and raised concerns regarding the ecological and human health implications. Continuous monitoring, source identification, public awareness, regulations, remediation, and long-term exploration are essential for addressing heavy metal pollution and its ecological impact. Therefore, valuable insights are provided for environmental management and conservation efforts.

Simple Summary: This study analyzes muscle and gill samples from 36 samples of 2 popular edible fishes from a subtropical wetland ecosystem to determine the amounts of harmful heavy metals, such as Pb, Hg, Zn, Cu, and Cr. The metal concentrations in the muscle and gills fluctuate, with zinc having the greatest concentration. Pb and Hg levels are higher than those that are acceptable for human consumption, while Cu, Zn, and Cr levels are within safe bounds. High amounts of Zn, Cu, and Cr may pose health hazards, according to risk indices. The research also highlights sources of heavy metals that are caused by humans and the natural world, highlighting the necessity of continual control and monitoring to guarantee the safety of fish for human consumption. The widespread occurrence of heavy metals in aquatic environments, resulting in their bioaccumulation within aquatic organisms like fish, presents potential hazards to human health. This study investigates the concentrations of five toxic heavy metals (Pb, Hg, Zn, Cu, and Cr) and their potential health implications in two economically important fish species (Otolithoides pama and Labeo bata) from a subtropical estuarine wetland system (Feni estuary, Bangladesh). Muscle and gill samples from 36 individual fish were analyzed using energy dispersive X-ray fluorescence (EDXRF). The results revealed that the average quantities of heavy metals in both fishes' muscle followed the declining order of Zn (109.41–119.93 mg/kg) > Cu (45.52–65.43 mg/kg) > Hg (1.25–1.39 mg/kg) > Pb (0.68–1.12 mg/kg) > Cr (0.31–5.82 mg/kg). Furthermore, Zn was found to be present in the highest concentration within the gills of both species. While the levels of Cu, Zn, and Cr in the fish muscle were deemed acceptable for human consumption, the concentrations of Pb and Hg exceeded the permissible limits (>0.5 mg/kg) for human consumption. Different risk indices, including estimated daily intake (EDI), target hazard quotient (THQ), hazard index (HI), and carcinogenic or target risk (TR), revealed mixed and varying degrees of potential threat to human health. According to the EDI values, individuals consuming these fish may face health risks as the levels of Zn, Cu, and Cr in the muscle are either very close to or exceed the maximum tolerable daily intake (MTDI) threshold. Nevertheless, the THQ and HI values suggested that both species remained suitable for human consumption, as indicated by THQ (<1) and HI (<1) values. Carcinogenic risk values for Pb, Cr, and Zn all remained within permissible limits, with TR values falling below the range of (10−6 to 10−4), except for Zn, which exceeded it (>10−4). The correlation matrix and multivariate principal component analysis (PCA) findings revealed that Pb and Cr primarily stemmed from natural geological backgrounds, whereas Zn, Cu, and Hg were attributed to human-induced sources such as agricultural chemicals, silver nanoparticles, antimicrobial substances, and metallic plating. Given the significance of fish as a crucial and nutritious element of a balanced diet, it is essential to maintain consistent monitoring and regulation of the levels and origins of heavy metals found within it. [ABSTRACT FROM AUTHOR]

This study investigated iron (Fe) accumulation in South Kalimantan's coastal swamp wetlands ecosystem, utilizing giant mudskipper fish as indicators of heavy metal pollution. By analyzing Fe levels in water, sediment, and fish organs over time, insights into its effects on the environment and human health were gained. Furthermore, through Atomic Absorption Spectrometry, Fe concentrations in Kuala Lupak's coastal wetland were measured, revealing significant correlations between Fe levels in water, sediment, and fish tissues. These results enhance our understanding and inform better management strategies. Anthropogenic and natural sources contribute to the accumulation of heavy metals, particularly Fe, with anthropogenic pollution being the most dominant. This study presented the escalating concentrations of Fe within the Kuala Lupak estuary and raised concerns regarding the ecological and human health implications. Continuous monitoring, source identification, public awareness, regulations, remediation, and long-term exploration are essential for addressing heavy metal pollution and its ecological impact. Therefore, valuable insights are provided for environmental management and conservation efforts. [ABSTRACT FROM AUTHOR]

Abstract Gobionellus stomatus, a fish species endemic to Brazil, was previously known to occur from the State of Piauí to the State of Rio Grande do Sul. Here we present the first record of this species for the State of Maranhão, specifically for the Upaon-Açu island, extending its distribution further west, to the coastal zone of the Amazon region. This species inhabits estuarine ecosystems susceptible to environmental pressures, such as pollution and the introduction of non-native species. Despite G. stomatus being classified as of least concern for conservation, it is crucial to highlight potential risks associated with human activities in these environments, emphasizing the importance of preservation measures to mitigate future impacts on the populations of this species, as well as of other estuarine gobies.

Functional characteristics of species are of great importance for understanding their roles in ecosystems and can be used to detect long‐term chances in the environment. We evaluated temporal changes (1983–1985 and 2017–2019) in taxonomic and functional indices of the fish fauna in shallow areas of a tropical bay heavily impacted by anthropogenic activities in recent decades. The hypothesis that functional indices change over time as a result of environmental degradation was tested. Our results showed a significant decrease in species richness and abundance over time, and in functional richness, while others functional diversity indices (divergency, evenness, and originality) remained stable. Thirteen functional groups were detected, some of which contained only one species, raising concerns about the loss of ecosystem functions due to ongoing changes. We also observed an increase in beta diversity over time, which may be the result of a decrease in local richness without leading to regional extinctions. Turnover was the most important process in structuring the fish fauna at the evaluated time scale. The relative stability of the functional structure and the higher levels of turnover seem to be related to the dominance of functional groups, within which species replace each other according to their responses to environmental filters that select for specific functional traits. Incorporating functional diversity indices and beta diversity variations in the fish community helped to enhance the existing information about this coastal system by offering improved estimates of biological diversity through diverse approaches. The predominance of turnover identified in the preset study suggests a dynamic and fluctuating species composition within the habitat. In this sense, habitat preservation should prioritize the protection of diverse habitats to accommodate a broad spectrum of species. [ABSTRACT FROM AUTHOR]

Blood reference values are indispensable parameters to monitor the health status of fishes. The objective of this work was to describe the morphology of the blood cells and provide haematological parameters of Dormitator latifrons in relation to sex and sampling site. The samples were collected from two natural sites, Larrea and the La Segua wetland, and from a fish farm. Erythrocytes, thrombocytes, lymphocytes, monocytes, neutrophils, and basophils were distinguished and characterised. Red blood cell count (RBC), white blood cell count (WBC), haemoglobin concentration (Hb), haematocrit value (Hcmt), mean corpuscular volume (MCV), and mean corpuscular haemoglobin concentration (MCHC) were not significantly different between males and females (p > 0.05). RBC, Hcmt, Hb, MCV, and neutrophil and monocyte counts were statistically higher in the fish from the La Segua wetland (p < 0.05), while most of these parameters were similar in fish from Larrea and the fish farm (p > 0.05). Significant difference (p < 0.05) in WBC was observed between sampling sites; the fish from natural environments showed higher values than cultured fish. The haematological parameters of D. latifrons vary depending on the site. Baseline information from this study may be a useful tool to monitor the health status of D. latifrons in culture systems. [ABSTRACT FROM AUTHOR]

The survey of fish diversity is an important part of the protection of the ecological health of rivers and lakes. Environmental DNA technology is a new tool to improve the accuracy of traditional morphological surveys of biodiversity and to monitor the amount of diversity. At present, there are few studies on monitoring fish diversity in lake inlets using eDNA technology. In this study, we used various types of estuaries in the Dianchi basin as the research object, used environmental DNA technology to monitor the fish diversity in typical estuaries, and analyzed the temporal and spatial changes and the relationship between environmental factors and fish diversity. In the Dianchi basin, we identified a total of 63 fish species belonging to 8 different orders, 21 families, and 51 genera across two seasons. The Carpidae family had the highest number of species, with Carassius auratus being the most prevalent species. The Shannon index analysis yielded a p-value of 0.0018 (<0.05), suggesting significant seasonal variations in the fish community structure within the typical estuaries of the Dianchi basin. Furthermore, the β-diversity accounted for 59.6% and 57% of the variations in fish communities among the various estuary types in March and July, respectively. Fish species varied considerably between estuaries, with Carassius auratus, Cyprinus carpio, Rhodeus sinensis, Acheilognathus chankaensis, and Coilia nasus all occurring at various points. The agricultural estuary differed substantially from the urban, suburban, and lake areas. Redundancy analysis revealed that the fish community structure during the dry period was primarily influenced by total phosphorus, pH, total nitrogen (TN), and chlorophyll. Conversely, during the rich period, the fish community structure was mainly influenced by dissolved oxygen and TN. This study demonstrated the utilization of environmental DNA technology in assessing the ecological health of rivers and lakes, specifically highlighting its effectiveness in exposing the ecological condition of a representative Dianchi estuary. [ABSTRACT FROM AUTHOR]

Microplastics (MPs) are an emerging contaminant potentially impacting organisms and ecosystem functioning. Despite the high abundance of MPs in Guanabara Bay, studies on MP ingestion are lacking. Analyses of 272 stomachs of Micropogonias furnieri, a key estuarine species, revealed that ~ 50% of fish ingested MPs, with an average of 3.7 MPs per individual. Polyester and polyethylene fibers were the dominant types of MPs found in both stomachs and bay sediments. Comparisons of the MP types in the fish stomachs and those previously described in the sediment showed that M. furnieri ingested MPs according to the availability but also exhibited selectivity for some rare MPs (i.e., blue and red fibers). Analyses of M. furnieri stomachs indicated that higher MP ingestion was associated with a larger quantity of food ingested, low digested food items, larger fish, dry season, and two bay locations, suggesting that this species serves as a valuable indicator of feeding area quality. MPs occurred only in stomachs with food, and estimates of egestion rates showed short residence time of food and MPs, indicating no MP accumulation in fish stomachs. The results also revealed that juveniles had more MPs in their stomachs per gram of body weight. MPs did not appear to impact M. furnieri feeding, but the effects of adsorbed chemicals on fish health require further evaluation. As M. furnieri ingests more food, it becomes more exposed to the effects of MPs, highlighting the MP threat to the ecosystem services provided by the bay, such as fish feeding areas. [ABSTRACT FROM AUTHOR]

Simple Summary: It is evident that microplastics can enter the human body via dermal contact, inhalation, and food intake and pose a significant threat to human health. Therefore, understanding microplastics is essential for protecting the environment and human health. This study identified 48.7 MPs on average in each fish of king mackerel, with varying concentrations in different tissues, such as the digestive tract, gills, and muscle. The size and characteristics of these MPs varied but many were <0.5 mm in size (97.74%) and fiber-like, with a lot in the muscle tissue, which raises concerns for human consumption. Three types of plastic polymers were identified in the MPs, likely from things like food packaging and plastic waste. The fish's muscle and digestive tract were significantly contaminated with MPs, indicating a high level of pollution. Microplastics (MPs) ingestion by fish signifies a worldwide threat to human health but limited research has examined their existence within the consumable portions (muscle) of fish. Thus, this study was undertaken to unveil the prevalence, characterization, and contamination extent of MPs across various body tissues, including the muscle of the king mackerel (S. guttatus) from the lower Meghna estuary in Bangladesh—a pioneering investigation in this region. In our analysis, we identified a total of 487 MPs, with an average abundance of 48.7 ± 20.3 MPs/individual. These MPs were distributed across different tissues, with respective concentrations of 0.84 ± 0.45 items/g in the digestive tract, 2.56 ± 0.73 items/g in the gills, and 0.3 ± 1.72 items/g in the muscle tissue. The observed variations among these tissue types were statistically significant (p < 0.05). Moreover, a significant positive correlation indicated that fish with higher weight had higher MPs in their gills and DT (digestive tract). The majority were <0.5 mm in size (97.74%) and exhibited a fiber-like shape (97.74%), with a notable prevalence of transparent (25.87%) and a pink coloration (27.92%). Remarkably, the majority of MPs were discovered within the size range of <0.5–1 mm (100%), particularly in the muscle tissue, signifying a substantial transfer of MPs into the human diet. Besides, we discovered only three polymer types of microplastics which could be attributed to the extensive use of food packaging, plastic containers, wrapping plastics, residential garbage, and plastic pipes that end up in the aquatic environment via river discharges. The contamination factor (CF) values of fish muscle (5.75) and the digestive tract (5.50) indicated that these fish organs were considerably contaminated (3 < CF < 6) with MPs. The pollution index of MPs (PLI > 1) indicated a high contamination level for MPs pollution of S. guttatus in the lower Meghna River estuary. [ABSTRACT FROM AUTHOR]

The widespread occurrence of heavy metals in aquatic environments, resulting in their bioaccumulation within aquatic organisms like fish, presents potential hazards to human health. This study investigates the concentrations of five toxic heavy metals (Pb, Hg, Zn, Cu, and Cr) and their potential health implications in two economically important fish species (Otolithoides pama and Labeo bata) from a subtropical estuarine wetland system (Feni estuary, Bangladesh). Muscle and gill samples from 36 individual fish were analyzed using energy dispersive X-ray fluorescence (EDXRF). The results revealed that the average quantities of heavy metals in both fishes’ muscle followed the declining order of Zn (109.41–119.93 mg/kg) > Cu (45.52–65.43 mg/kg) > Hg (1.25–1.39 mg/kg) > Pb (0.68–1.12 mg/kg) > Cr (0.31–5.82 mg/kg). Furthermore, Zn was found to be present in the highest concentration within the gills of both species. While the levels of Cu, Zn, and Cr in the fish muscle were deemed acceptable for human consumption, the concentrations of Pb and Hg exceeded the permissible limits (>0.5 mg/kg) for human consumption. Different risk indices, including estimated daily intake (EDI), target hazard quotient (THQ), hazard index (HI), and carcinogenic or target risk (TR), revealed mixed and varying degrees of potential threat to human health. According to the EDI values, individuals consuming these fish may face health risks as the levels of Zn, Cu, and Cr in the muscle are either very close to or exceed the maximum tolerable daily intake (MTDI) threshold. Nevertheless, the THQ and HI values suggested that both species remained suitable for human consumption, as indicated by THQ (−6 to 10−4), except for Zn, which exceeded it (>10−4). The correlation matrix and multivariate principal component analysis (PCA) findings revealed that Pb and Cr primarily stemmed from natural geological backgrounds, whereas Zn, Cu, and Hg were attributed to human-induced sources such as agricultural chemicals, silver nanoparticles, antimicrobial substances, and metallic plating. Given the significance of fish as a crucial and nutritious element of a balanced diet, it is essential to maintain consistent monitoring and regulation of the levels and origins of heavy metals found within it.

Estuarine fish assemblages are undergoing rapid change due to invasions of non-native species and physicochemical alteration of their habitats. Here, we examine the novel fish assemblages of the upper San Francisco Estuary (SFE) by first placing the fishes into ecological assemblages (EAs) of species that co-occur based on salinity, macrohabitat, and diet. We then used the morphological characteristics of each species to place them into functional groups (FGs) or potentially functionally independent species (FIS). Our question was: are there native and non-native species that occupy a similar niche in ecomorphological space, and thus potentially interact? Then, based on our results, we sought to understand if there is evidence that native species are being displaced by non-native species. The 43 species examined were placed into 17 EAs of potentially interacting species. Within these EAs, we identified 13 FGs and 13 FIS based on ecomorphology. Six FGs contain both native and non-native species indicating organization independent of the origin of the species. However, in most cases the native species were present in low abundance or were in categories of risk. Five FGs contained just non-native species that were found mainly in altered habitats and two FGs contained just native species. Overall, both native and non-native species appear to form a novel assemblage, although the decline of some native species in the face of potential competitors and predators suggests the final assemblage has not yet been determined. In addition, ongoing alterations of the SFE ecosystem increase the likelihood that invasions of new species will continue, causing further changes to the assemblage.

The fish guild structure of 96 fish species inhabiting the Vembanad Lake, an open, large, well-mixed coastal estuary along the south-west coast of India, was studied based on samples from upper (freshwater), middle (estuarine), and lower (saline) zones representing three major seasons (monsoon, post-monsoon, and pre-monsoon). Functional group assessment revealed seven ecological guilds (marine estuarine opportunists, freshwater, marine estuarine dependent, estuarine, catadromous, anadromous, and amphidromous), six feeding guilds (detritivore, zooplanktivore, herbivore, zoobenthivore, omnivore, and carnivore), three vertical distribution guilds (demersal, benthopelagic, and pelagic), five reproductive-mode functional groups (oviparous with pelagic eggs, oviparous with benthic eggs, oviparous guarders, viviparous and ovoviviparous), and five flow-preference guilds (rheophilic A1, eurytopic, rheophilic A2, rheophilic B, and rheophilic C). The estuary was characterized by high species diversity, low individual species abundance, complex guild structure, varying fish diversity from upper to lower estuary and higher proportion of marine rather than 'true' estuarine species. The absence of a significant relationship between season and fish guild structuring could be due to high resource availability in the estuary and low ecological connectivity between upper and lower estuarine zones as a result of anthropogenic interventions in the middle zone. Salinity variations considerably influenced the fish guild formation in the estuary. A drastic change in the hydrography of the estuary over the past sixty years due to topographical alterations has transformed the fish guilds resulting in a considerable increase in freshwater species and a reduction in marine and estuarine-dependant species. [ABSTRACT FROM AUTHOR]

Context: Oysters provide structured habitat along coastal margins, but owing to the high turbidity of many estuaries, characterising the faunal communities that utilise oyster reefs typically requires direct capture, which is potentially lethal or destructive. Acoustic imaging sonar can non-destructively sample the abundance and size of swimming organisms (nekton), but collection of data from acoustic imaging files requires substantial processing time following field sampling. Aims: We compared five alternate data examination protocols that could be applied to acoustic imaging files from intertidal oyster reefs and identified a protocol (analysing randomly chosen 3 of 5 min of imagery recordings) that reduces parameter estimation bias and processing time. Methods: To demonstrate the utility of this protocol, we investigated diel differences in fish use of fringing oyster reefs. Key results: During day-time and night-time sampling, we respectively recorded 4535 and 1924 fish across a size range of 1–52 cm. We found no difference between day and night in relative abundance, mean size, or size-spectra of the fish community inhabiting reefs. Conclusions and implications: Active acoustic imaging can be an effective, non-destructive method to characterise faunal communities in shallow, turbid habitats and can be used to test hypotheses regarding the ecology of these ecosystems. Sampling the mobile fauna that use oyster reefs as habitat is difficult because of the complex nature of the reef and the often turbid conditions found within estuaries. We used acoustic imaging sonar to estimate abundance and size of fishes on fringing, intertidal oyster reefs in South Carolina, USA, and recommend a data processing protocol to standardise future studies utilising this promising, non-lethal sampling methodology. [ABSTRACT FROM AUTHOR]

Estuaries are very productive habitats that serve as spawning and nursery grounds for fisheries species. The Rio de la Plata (RdP) Estuary and its maritime front sustain valuable fisheries for Argentina and Uruguay. Micropogonias furnieri, the coastal fish species historically representing highest catches, has declined landings in recent decades. To enhance our understanding on how natural variability influences this resource and improves its management, we analysed the effect of environmental conditions on M. furnieri' s commercial landings in the long term using generalized linear and additive models (GLMs and GAMs). Explanatory variables, with up to a 10-year lag, included sea surface temperature, turbidity, salinity, wind, river runoff, and climatological indices: El Niño-Southern Oscillation (ENSO), the Southern Annular Mode (SAM) and the Southern Oscillation Index (SOI). Time-lagged analyses for single-covariate models reveal higher deviances explained (DE) at 2, 6, 7, and 8-year lags. Turbidity and salinity, followed by wind and temperature, are the most common variables affecting catches of M. furnieri for GLMs and GAMs. The absence of significant models with only climatological indices or river discharge indicates the impact of large-scale climate fluctuations and river runoff on the RdP Estuary conditions. The best-fitting GLM model includes SAM, turbidity, and wind (DE = 78.8%), whereas the GAM model includes turbidity and wind (DE = 86.4%). Sensitivity of M. furnieri 's catches to climatic signals (ENSO, SAM, SOI) is described for the first time. Our findings provide insights for authorities to implement management measures beyond fishing quotas encompassing environmental shifts in the long-term. • M. furnieri 's inter-annual catch variability in response to environmental conditions was analysed. • Natural variability's impact on catches was analysed using generalized linear (GLM) and generalized additive (GAM) models. • GAMs had a higher explanatory power than GLMs in capturing environmental variability dynamics in fisheries. • Turbidity and salinity followed by wind and temperature were the most common variables affecting catches. • M. furnieri 's catch variability was linked to ENSO, SAM and SOI cycles. [ABSTRACT FROM AUTHOR]

Microplastics (MPs) ingestion by fish signifies a worldwide threat to human health but limited research has examined their existence within the consumable portions (muscle) of fish. Thus, this study was undertaken to unveil the prevalence, characterization, and contamination extent of MPs across various body tissues, including the muscle of the king mackerel (S. guttatus) from the lower Meghna estuary in Bangladesh—a pioneering investigation in this region. In our analysis, we identified a total of 487 MPs, with an average abundance of 48.7 ± 20.3 MPs/individual. These MPs were distributed across different tissues, with respective concentrations of 0.84 ± 0.45 items/g in the digestive tract, 2.56 ± 0.73 items/g in the gills, and 0.3 ± 1.72 items/g in the muscle tissue. The observed variations among these tissue types were statistically significant (p < 0.05). Moreover, a significant positive correlation indicated that fish with higher weight had higher MPs in their gills and DT (digestive tract). The majority were 1) indicated a high contamination level for MPs pollution of S. guttatus in the lower Meghna River estuary.

Biomarkers are used to assess health conditions of organisms and consequently to indicate environmental hazard, being important tools to address the effects of pollutants on environmental quality. We analyzed the hepatopancreas and kidney of two sciaenid fishes, the southern kingcroaker Menticirrhus americanus and the whitemouth croaker Micropogonias furnieri in the Paraty Bay (control system) and in the Sepetiba Bay (altered system) in southeast Brazilian coast. The altered bay is heavily affected by human activities, compared to the control bay, where the human interference is much reduced. The tested hypothesis was that these species respond to environmental changes with fishes from the altered bay having more histological changes in the hepatopancreas and kidney compared with those from the control bay. The fish hepatopancreas and kidneys from the altered system had high 50–100% incidence of changes and the histopathological alteration index reached values above 100 in the hepatopancreas and kidney, indicating irreversible damage to the organs. In contrast, in the control system, those values ranged between 20 and 100, indicating moderate and severe organ damages. These findings suggest that these organs and these two fish species can be considered useful biomarkers to assess environmental contamination in tropical bays. [ABSTRACT FROM AUTHOR]

Functional diversity can be used to help understanding the processes shaping biological communities and the effects of human disturbances on the ecosystem's services. Untangling these biological processes is crucial to apply effective policies aiming the biodiversity conservation. Temporal changes (1983–1985, 1999–2001 and 2017–2019) in five functional indices (functional richness, divergence, evenness, specialization and originality) of the fish communities in two zones (inner and outer) of shallow areas in a tropical bay heavily human-impacted in recent decades were evaluated. The tested hypothesis was that functional indices decrease over time, because of the environmental degradation. A substantial decrease in species richness and abundance in the more recent periods (1999–2002 and 2017–2019) compared to 1983–1985 was observed. However, the functional structure remained relatively stable, with the exception of functional richness that showed a significant decrease over time. The apparent stability in the other functional indices may be due to the presence of dominant and functionally redundant species over time that compensates for the loss of species while maintaining similar functions. It was also discovered that decreases in fish richness in shallow bay areas result in losses in functional richness, with resident fish and benthivorous species being the most affected by environmental degradation. By employing a comprehensive approach that integrates the use of functional indices and taxonomic diversity to assess temporal changes in the fish community, it provides a broader understanding of ecological processes. Such insights could prove invaluable in guiding the implementation of conservation strategies. • Changes over three decades in fish functional indices in a tropical bay was evaluated. • A substantial temporal decrease in species richness and abundance was observed. • Functional structure remained stable, but the functional richness decreased over time. • Stability in other functional indices was due to dominant and functionally redundant species. • Redundant species compensates losses of species while maintaining similar functions. [ABSTRACT FROM AUTHOR]

Context: Landscape modification alters the condition of ecosystems and the structure of terrain, with widespread impacts on biodiversity and ecosystem functioning. Seafloor dredging impacts a diversity of flora and fauna in many coastal landscapes, and these processes also transform three-dimensional terrain features. The potential ecological significance of these terrain changes in urban seascapes has, however, not been investigated. Objectives: We examined the effects of terrain variation on fish assemblages in 29 estuaries in eastern Australia, and tested whether dredging changes how fish associate with terrain features. Methods: We surveyed fish assemblages with baited remote underwater video stations and quantified terrain variation with nine complementary metrics (e.g. depth, aspect, curvature, slope, roughness), extracted from bathymetry maps created with multi-beam sonar. Results: Fish diversity and abundance were strongly linked to seafloor terrain in both natural and dredged estuaries, and were highest in shallow waters and near features with high curvature. Dredging, however, significantly altered the terrain of dredged estuaries and transformed the significance of terrain features for fish assemblages. Abundance and diversity switched from being correlated with lower roughness and steeper slopes in natural estuaries to being linked to features with higher roughness and gentler slopes in dredged estuaries. Conclusions: Contrasting fish-terrain relationships highlight previously unrecognised ecological impacts of dredging, but indicate that plasticity in terrain use might be characteristic of assemblages in urban landscapes. Incorporating terrain features into spatial conservation planning might help to improve management outcomes, but we suggest that different approaches would be needed in natural and modified landscapes. [ABSTRACT FROM AUTHOR]

Sphaeromyxa azevedoi n. sp. is described from the gall bladder of the goby Gobioides grahamae (Gobiidae) captured on the Paracauari River in Salvaterra, on Marajó Island, northern Brazil. A total of 50 G. grahamae specimens were analysed, and 15 (30%) were parasitised by the plasmodia and myxospore of Sphaeromyxa azevedoi n. sp. Large plasmodia were observed floating in the bile. These plasmodia were flat, rounded, oval or elongated, and of varying sizes. The mature myxospores, found singly or in pairs, were 27.1 ± 2.7 (20.5–30.1) μm Length and 3.8 ± 0.2 (3.5–4.4) μm Width in the valvular view. The myxospore has two polar capsules of equal size, 8.1 ± 0.6 (7.4–9.4) μm in length and 2.9 ± 0.2 (2.3–3.3) μm in width. A polar tubule was observed in each capsule, arranged perpendicularly to the principal axis, with three or four coils. The histological analysis showed that the plasmodia and myxospore are located in the lumen of the gall bladder, arranged in pairs, and the epithelium of the gall bladder presented multifocal necrosis. The SSU rDNA of Sphaeromyxa azevedoi n. sp. clusters in the 'balbianii' group of the Sphaeromyxa clade. The morphological characteristics and molecular phylogeny of Sphaeromyxa azevedoi n. sp. support its classification as a new species of the genus Sphaeromyxa, which represents an important advancement in the understanding of the diversity of the myxozoan parasite fauna of Brazilian fishes, especially considering that the new species may be detrimental to the host, a commercially important Brazilian fish species. [ABSTRACT FROM AUTHOR]

The study reported Thryssa stenosoma, as a new host of isopod Nerocila depressa infestation. Furthermore, the record of Nerocila depressa from the Narmada estuary is of first kind in the West Coast of India. Thryssa stenosoma, commonly known as slender thryssa forms an important commercial fish species at Bhadbhut, a part of the Narmada estuary. The prevalence of N. depressa infestation was 17.39% with a mean intensity of 2.8. in T. stenosoma, showing a low rate of infestation. The present information would form a new addition of isopod infestation to the list of parasitic diseases of estuarine fishes in India. [ABSTRACT FROM AUTHOR]

The loss of mangrove areas due to anthropogenic activities has triggered efforts to recover or restore these ecosystems, their functions, and associated diversity. Such functions include nursery areas and energy flow through trophic relationships for a large variety of inhabitant species (e.g., fish). The food webs and trophic dynamics of estuarine fish provide important information on the food resources in mangrove ecosystems and their response to restoration processes. Nonetheless, few studies focus on using fish feeding characteristics as an approximation to assess the conservation or recovery status of these aquatic ecosystems. Thus, the aim of the present study was to compare the trophic dynamics of an ichthyic community in a mangrove ecosystem related to karstic wetlands in the Mexican–Caribbean using freshwater, estuarine, and marine fish species as bioindicators of the restoration process in mangroves. Stomach contents were analyzed for eight species of fish inhabiting specific mangrove zones (1—conserved zone, and 2—restored zone; a zone exposed to ecological restoration processes due to impacts of anthropic activities) related to karstic wetlands in the Mexican–Caribbean. Four feeding characteristics were considered: trophic guild, trophic level, feeding strategy, and prey abundance. Results showed differences and changes in the use of food sources at the trophic level mainly for Floridichthys polyommus, changing from a secondary consumer in the conserved zones to a primary consumer in the restored zones. This suggests that the feeding characteristics of the inhabiting fish are related to the mangrove’s conservation/restoration status and the trophic dynamics in the community. The results of this study are relevant as a tool for mangrove restoration plans regarding the analysis of fish and their food prey, in order to perform an easy and rapid assessment to determine the conservation/restoration status of these aquatic ecosystems from a functional perspective.

Acidized water environment can impact many physiological processes of aquatic animals. The response of the head kidney to acidification, especially the immune response, is of great significance to health. This study analyzed the histological and transcriptional changes under different acidification levels (C group, pH 8.1; P group, pH 7.4; E group, pH 3.5) in the short term (12 h, 36 h and 60 h) in the head kidney of juvenile L. calcarifer. The results showed that the acidification of the water environment caused tissue damage to the head kidney of L. calcarifer, and the damage appeared earlier and was stronger in the extreme pH group. The transcriptional response of L. calcarifer head kidney increased with the increase of acidification level. The two treatments transcriptional responses showed different trends in terms of time. After KEGG function enrichment, with the increase of stimulation time, the proportion of down-regulated pathways was increasing, and the types of pathway enrichment at different acidification levels were quite different at the initial stage. At 12 h, the first category in the P group with the most significant number of pathways was ‘Metabolism’, and the first category in the E group with the largest number of pathways was ‘Human Diseases’. At 60 h, the enrichment pathways of the two groups were highly overlapping in immune-related pathways, which contained 26 common DEGs. They had a dominant expression pattern. In the P group, the expression level decreased with time. In the E group, the down-regulation degree of expression level at 12 h reached the level of the P group at 60 h, and the expression level remained low until 60 h. Through the correlation network, interferon regulatory factor 7 (IRF7), Tripartite motif containing-21 (TRIM21), Signal transducer and activator of transcription 1 (STAT1) and Signal transducer and activator of transcription 3 (STAT3) were found to have the most correlation with other genes. In this study, juvenile L. calcarifer showed different coping strategies to different levels of acute acidification stress, but all of them resulted in the extensive weakening of head kidney immune function.

The present study was conducted to detect a correlation between Pb content in sediment and muscle of fish (Mystus gulio Ham. - Buch.) and downstream stretches (three study sites) of the of the river Hooghly, West Bengal, India. The study sites were selected at Batanagar (Bt), Budge Budge (Bg) and Birlapur (Br) sites. The samples viz. sediment and muscle of fish were collected and estimated by using atomic absorption spectrophotometer. The Pearson correlation coefficient analysis was performed to know the association between these sites and sediment as well as muscle during pre-monsoon season. The study sites observed both significant positive (P<0.05) and negative correlation with sediment of river Hooghly at downstream while significant (P<0.05) positive correlation was observed between the study sites and muscle of the fish specimen (Mystus gulio). The findings pose the risk of accumulation may be lower in fish muscle due to positive correlation, but negative correlation may lead to harmful impact in the study site for sediment. In future, this study may be beneficial to determine the water and sediment quality status in different stations of river Hooghly as well as other metals content in different fish species. [ABSTRACT FROM AUTHOR]

High variability in environmental conditions in both space and time once made the upper San Francisco Estuary (the Estuary) highly productive for native biota. Present conditions often discourage native species, providing a rationale for restoring estuarine variability and habitat complexity. Achieving a variable, more complex Estuary requires policies which: (1) establish internal Sacramento–San Joaquin Delta (the Delta) flows that create a tidally mixed, upstream–downstream gradient in water quality, with minimal cross-Delta flows; (2) create slough networks with more natural channel geometry and less diked, riprapped channel habitat; (3) increase inflows from the Sacramento and San Joaquin rivers; (4) increase tidal marsh habitat, including shallow (1 to 2 m) subtidal areas, in both fresh and brackish zones of the Estuary; (5) create/allow large expanses of low salinity (1 to 4 ppt) open water habitat in the Delta; (6) create a hydrodynamic regime where salinities in the upper Estuary range from near-fresh to 8 to 10 ppt periodically, to discourage alien species and favor desirable species; (7) take species-specific actions that reduce abundance of non-native species and increase abundance of desirable species; (8) establish abundant annual floodplain habitat, with additional large areas that flood in less frequent wet years; (9) reduce inflow of agricultural and urban pollutants; and (10) improve the temperature regime in large areas of the Estuary so temperatures rarely exceed 20 °C during summer and fall months. These actions collectively provide a realistic if experimental approach to achieving flow and habitat objectives to benefit desirable species. Some of these goals are likely to be achieved without deliberate action as the result of sea level rise, climate change, and levee failures, but in the near term, habitat, flow restoration and export reduction projects can enhance a return to a more variable and more productive ecosystem.

In tropical estuaries, fish diversity varies spatially and temporally due to behavioral processes such as reproductive migrations, predator avoidance, and foraging, which are affected by water quality. Eutrophication is one of the main factors affecting water quality in estuaries. The objective of this study was to determine variation in fish assemblage explained by fluctuating water quality in the Buenaventura Bay. Fish were captured using artisanal trawl nets during the wet, dry, and transitional seasons at four sampling sites. Additionally, alkalinity; phosphate, nitrite, and nitrate concentrations; dissolved oxygen; pH; temperature; and suspended solids were measured. Multivariate analysis was used to assess the effect of water quality on fish assemblage. In Buenaventura Bay, the assemblage composition of Pseudupeneus grandisquamis, Daector dowi, and Citharichthys gilberti was affected by nitrate concentration. Moreover, large fish biomasses were associated with high nitrite concentration, intermediate salinity, and low dissolved oxygen, suggesting that these estuaries are dominated by species tolerant to poor water quality. Species richness was associated with low nitrate and phosphate concentrations, more suitable water quality indicators, and intermediate temperatures. These results suggest that the deteriorating water quality of estuaries as a result of the anthropogenic impact could increase dominance and decrease richness, resulting in structural changes of fish assemblages. [ABSTRACT FROM AUTHOR]

Photophase and illumination affect many fish activities. In this study, we examined their effects on the critical swimming velocities (Ucrit), swimming gait patterns, and oral grasping behavior of five California estuarine fishes. All species (4-5 cm SL) swam similarly (mean Ucrit range:30-36 cm/s) under day/light conditions. However, both nighttime photophase and darkness decreased Delta Smelt (Hypomesus transpacificus) swimming velocities. Congeneric Wakasagi (H. nipponensis) swimming performance also decreased at night/dark conditions. Regardless of photophase and illumination, Delta Smelt, Wakasagi, and Splittail (Pogonichthys macrolepidotus) exhibited three swimming gaits: intermittent stroke-and-glide at low velocities, continuous stroking at moderate velocities, and intermittent burst-and-glide at high velocities near Ucrit. In contrast, Chinook Salmon (Onchorhynchus tshawytscha) used only two swimming gaits: continuous stroking and burst-and-glide under all conditions. Inland Silversides (Menidia beryllina) used these two gaits under light conditions and all three gaits under dark conditions. Some Wakasagi, Splittail, and Chinook Salmon orally grasped the upstream screen in the flume at moderate to high water velocities. Oral grasping does not require jaw teeth and may represent adaptive behavior in natural habitats. Regarding vulnerability to water diversions that operate in the dark at night, the threatened Delta Smelt and introduced Wakasagi, comparatively, may be more at risk than the other species.

The effect of hydrological connectivity of the fish assemblages was assessed on a floodplain in the SE Gulf of California, Mexico using a before–after control-impact (BACI) design. Community structure attributes of species abundance, biomass, richness, diversity, and differences in the structure of fish assemblages were compared between two periods (January to June in 2011 and 2015) and two flood plains, one designated as the control zone which was divided by a road, and another one designated as the treatment zone which from January to June 2011 was divided by a road, and then sampled from January to June 2015, as the site was rehabilitated by removing the road in the year 2012. Fish were sampled at monthly intervals using a seine net at different stations in both floodplains. A total of 7024 organisms, comprising of 14 species belonging to 11 families, were analyzed. In the control zone during both periods and in the treatment zone before removal of the road Poecilia butleri was the most abundant species and two exotic species (Tilapia) accounted for more than 95% of the total biomass. After the removal of the road in the treatment zone Poeciliopsis latidens was the most abundant species and the relative biomass of both species of tilapia decreased to 85%, but was still the most important in terms of biomass. However, richness and diversity were higher and the structure of the fish assemblages was different in the treatment zone after the road was removed, due to the presence of species with estuarine and marine affinity in this zone and period. Our results indicate that hydrological connectivity proved to be a key factor influencing the fish composition and abundance in the floodplain system in the region. Hence, a better hydrological connectivity implied higher abundance and diversity, likely related to an increase in the habitat complexity. The priority in the management of the ecological functioning of the floodplain system should be set on minimizing the modifications of the natural flow and thus avoiding the changes on the fish biota.

The present study comprises the first systematic analysis of the limits of upstream movement by some fish species that use the estuarine area of the Patos Lagoon basin in southern Brazil. The Sinos River sampling program included 86 sites, sampled from 1998 to 2014, covering lowland stretches and headwater streams. The Guaíba sampling program was conducted from February 2011 to March 2013 and comprised 59 independent samples. Six fish species using estuarine areas occur in the upper Patos basin, 250–500 km from the Patos Lagoon outlet to the Atlantic Ocean. Parapimelodus nigribarbis specimens ranged from 11.3 to 18.9 cm (median = 13.3 cm) in length, i.e., were adults (Sinos, n = 459; Guaíba, n = 149). The species was captured almost 500 km from the Patos outlet, as far as 180 km upstream in the Sinos main channel. In Guaíba Lake, the species was captured mainly in autumn, although it was more abundant in winter and spring in the Sinos River. Lycengraulis grossidens was captured in the Sinos Basin, restricted to the lower stretches in spring and summer months (n = 7). In Guaíba Lake (n = 134) the species occurred throughout the lake and year-round, and was ten times more abundant in spring. Most specimens were adult (8.2–26.9 cm, median = 20.0 cm). Most Micropogonias furnieri individuals (n = 63) were juveniles (10.7–33.4 cm, median = 14.2 cm). The species was not captured in the Sinos Basin. In Guaíba Lake M. furnieri occurred predominantly in the southernmost part (downstream) and was more abundant (>10×) in winter. Genidens genidens (n = 27) was captured only in summer in the southern part of Guaíba Lake (closest to the outlet). Most individuals were adults (24.5–34.0 cm, median = 27.8 cm). Genidens barbus (n = 7) was restricted to spring and summer months and was captured only in southern (near-outlet) parts of Guaíba Lake, comprising mainly large juveniles and adults (31.5–68.0 cm, median = 37.9). Mugil liza (n = 13) appeared in spring in relatively low abundances but was widespread throughout Guaíba Lake during the summer. The species was not captured in the Sinos sampling program. The size profile comprised specimens nearing maturity (34.3–45.5 cm, median = 38.9 cm). Finally, we suggest possible biological cycles for these species that combine these new distribution data with published information.

Introduction: Since the middle of the XXth century the Gulf of Nicoya estuary (10o N & 85o W) has been the main source of numerous fishing resources, such as mollusks, crustaceans, and fish. The estuary is presently under the increasing impact of local, regional and global stressors. The expeditions on board the Skimmer (1979-1980) and Victor Hensen (1993-1994) research vessels provided multidisciplinary data on the estuary in support of management policies. However, updated information is still needed. Objectives: To update the published lists of fish species from both expeditions and make suggestions for new research areas for future evaluations of the ecosystem. Methods: The fish collections by the Skimmer covered a depth range of 10 to 50 m using an otter trawl net, and those aboard the Victor Hensen were made between 10 to 228 m depth using otter and beam trawl nets. The identification of most of the fish species and the measurement of its lenghts were made on board of both vessels. The species names were updated based on recent literature and the web page World Register of Marine Species (WORMS). The list of species identified in recent years based on voucher specimens from the estuary and deposited in the Ichthyology Collection of the Museum of Zoology, University of Costa Rica, was also included. Results: The total number of identified species from both vessels is 268. A new species of Pontinus is under description. Of the total, 19 are cartilaginous fishes and 249 are bony fishes. The Sciaenidae and the flatfishes were represented by 31 and 32 species, respectivley. The flatfish genus Symphurus was the most diverse, with 11 species. Eighteen species were identified after the publication of the original lists. Eight species were described based on specimens collected during the expeditions: Gymnothorax phalarus, Notarius biffi, N. cookei, Ophicthus mecoptera, O. melope, Sphoeroides rosenblatti, Trinectes xanthurus and Urotrygon cimar. The five longer specimens collected by both vessels, were: the longtail sting ray Hypanus longus (117 cm), the pike conger Cynoponticus coniceps (103 cm), the brown sea catfish Sciades dowii (87 cm), the electric ray Narcine brancroftii (80 cm), and the queen corvina Cynoscion albus (75 cm). Conclusions: In view of the increasing number of users of the estuarine resources, it is urgent a multidisciplinary evaluation of the ecosystem in support of new management policies. The expected results may facilitate updating the Gulf of Nicoya Trophic Model, a management tool available for the estuary since 1998 and based mainly on information gathered during both expeditions. Ecosystem stressors, such as the extraction of resources, the input of pollutants and its possible link to endocrine disruption, as well as the presence of natural barriers such as hypoxia at deeper waters at the mouth of the estuary must be taken into account in a future evaluation. [ABSTRACT FROM AUTHOR]

The present study evaluates physicochemical variables, perform a microbiological analysis as well as determine heavy metal concentrations in the water and muscle tissue of fishes from the Cachorros River. The analysis of metal concentrations in the estuarine water revealed high levels of Fe and Al, with values above the limits established by Brazilian legislation. The concentration of total coliforms and thermotolerant coliforms tended to be higher in the rainy season. Regarding metal concentrations in the muscle tissue of fishes, high levels of Pb and Cd were found, especially in carnivorous and detritivorous species, with values above the limits established by national legislation. Two-factor analysis of variance revealed that only Pb demonstrated a significant interaction between seasonality and the feeding habits of the fish fauna, with higher concentrations of this metal in the dry season among detritivorous species in comparison to herbivorous species. The present findings demonstrate the contamination pattern that has been occurring in the Cachorros River, as evidenced by the concentration of trace metals in both the water and muscle tissue of fishes, which are an important source of protein as well as an economic resource for the population of this river basin. [ABSTRACT FROM AUTHOR]

Zinc is an essential trace mineral that is involved in many biological processes. In elevated concentrations, this metal may have toxic effects for aquatic organisms. Physicochemical properties of water, such as salinity and hardness, can influence the bioavailability of zinc and, therefore its toxicity in aquatic environments. Therefore, this study aimed investigate the influence of salinity, hardness on Zn toxicity on the behaviours and biochemical parameters of the estuarine guppy (Poecilia vivipara). The fish were exposed to waterborne zinc (500 μg L−1) in salt water (25 ppt) or hard water (120 mg L−1 CaCO3). For behavioural analysis, the locomotive and exploratory parameters of fish in novel environment and light–dark tests were evaluated. We observed that exposure to hard water decreased the distance covered by the fish, and when zinc also present the vertical exploratory behavior decreased. When zinc was tested alone, an increase in the maximum speed of fish was recorded. Activities of antioxidant enzymes, levels of lipid peroxidation, protein carbonylation, total peroxidation and, reactive oxygen species content, antioxidant capacity against peroxyl radicals, non-proteins thiols levels, acetylcholinesterase and Na+/K+-ATPase activities were evaluated in the whole fish body. The integrated biomarker response was calculated for each parameter to aid in the interpretation of the results and indicated that hard water containing zinc had the greatest effect on the biochemical parameters of the fish. In general, neither salinity nor hardness were totally effective in protecting the guppy from the biochemical damage caused by exposure to zinc. [ABSTRACT FROM AUTHOR]

This study investigated the secondary stress responses of Paralichthys orbignyanus exposed to ammonia and nitrite and after recovery. Fish were exposed to 0.12, 0.28, and 0.57 mg NH3‐N/L, or 5.72, 10.43, and 15.27 mg NO2‐N/L for 10 d followed by the same time length for recovery. Ammonia‐ and nitrite‐free water was used as a control treatment. Blood samples were collected after 1, 5, and 10 d of exposure and after recovery. Fish exposed to ammonia presented lower and higher glucose levels after 10 d of exposure and recovery, respectively. Ammonia induced initial and transient ionic disturbances and metabolic alkalosis. Nitrite exposure caused hyperglycemia, increased plasma K+ levels, and respiratory alkalosis, whereas metabolic acidosis was observed after recovery. Increased proportion of monocytes and/or granulocytes and reduced number of lymphocytes were demonstrated in fish exposed to 0.28 mg NH3‐N/L (Day 1) and 10.43 mg NO2‐N/L (Day 5) and after recovery in the 0.28 and 0.57 mg NH3‐N/L treatments. Exposure to ammonia decreased the proportion of granulocytes on Day 5. In conclusion, exposure to concentrations at 0.12 mg NH3‐N/L and 5.72 mg NO2‐N/L provoked physiological disorders in Brazilian flounder. Nonetheless, fish exposed to 5.72 mg NO2‐N/L following a 10‐d recovery period showed complete resumption of homeostasis. [ABSTRACT FROM AUTHOR]

Copyright of Boletín Científico Centro de Museos de Historia Natural is the property of Universidad de Caldas and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this study, we evaluate the fish-based ecosystem services (ES) of Chettuva, a small tropical estuary (CE) on the south-west coast of India. Besides the direct benefits (provisioning and cultural), the primary regulatory and supporting services provided by fish in estuaries were also documented using secondary data and focused group discussions (FGD). The major obstacles impeding the fisheries-based ES were also identified, and priority-based management options were proposed. The annual economic value of the major fish-based ES of the estuary was estimated to be ₹814.55 million (₹36.96 million for provisioning, ₹569.52 million for supporting, ₹177.6 million for regulating and ₹30.47 million for cultural and information services including recreation, tourism, scientific and information services, respectively). The estuarine fishery in CE is still traditional, employing non-motorized boats and supporting the livelihood of about 300 active fishers. Our findings revealed that stakeholders rated higher values on provisioning, supporting, and cultural services while providing little significance on the regulating services. The current findings indicated that, as the primary means of livelihood, fisheries not only provide a pragmatic overview of the economic value of estuarine systems but also signifies the use of fisheries-based ES as a valuable tool in developing an ecosystem-based management plan. Based on the findings, it would be reasonable to highlight the need for ES-based approach for resource conservation in fisheries management of the small tropical estuaries. • The fisheries-based ecosystem services of a small tropical Indian estuary-Chettuva were evaluated. • The estuary has a subsistence fishery with 300 fishers with an income of ₹16.54 million. • Stakeholders focus on provisioning, supporting, and cultural services than regulating type. • The annual economic value of ecosystem services was estimated to be ₹814.55 million. • The challenges and management measures for efficient delivery of ES are discussed. [ABSTRACT FROM AUTHOR]

Copyright of Revista Mexicana de Biodiversidad is the property of Universidad Nacional Autonoma de Mexico, Instituto de Biologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To withstand the pressures of a rapidly changing world, resilient ecosystems should exhibit compensatory dynamics, including uncorrelated temporal shifts in population sizes. The observation that diversity is maintained through time in many systems is evidence that communities are indeed regulated and stabilized, yet empirical observations suggest that positive covariance in species abundances is widespread. This paradox could be resolved if communities are composed of a number of ecologically relevant sub-units in which the members compete for resources, but whose abundances fluctuate independently. Such modular organization could explain community regulation, even when the community as a whole appears synchronized. To test this hypothesis, we quantified temporal synchronicity in annual population abundances within spatial guilds in an estuarine fish assemblage that has been monitored for 36 years. We detected independent fluctuations in annual abundances within guilds. By contrast, the assemblage as a whole exhibited temporal synchronicity--an outcome linked to the dynamics of guild dominants, which were synchronized with each other. These findings underline the importance of modularity in explaining community regulation and highlight the need to protect assemblage composition and structure as well as species richness. [ABSTRACT FROM AUTHOR]

Copyright of Revista de Biologia Marina y Oceanografía (RBMO) is the property of Universidad de Valparaiso, Facultad de Ciencias del Mar and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We studied the effects of metabolic cold adaptation (MCA) in two populations of a eurythermal species, spotted seatrout (Cynoscion nebulosus) along the U.S. East Coast. Fish were captured from their natural environment and acclimated at control temperatures 15 °C or 20 °C. Their oxygen consumption rates, a proxy for metabolic rates, were measured using intermittent flow respirometry during acute temperature decrease or increase (2.5 °C per hour). Mass-specific standard metabolic rates (SMR) were higher in fish from the northern population across an ecologically relevant temperature gradient (5 °C to 30 °C). SMR were up to 37% higher in the northern population at 25 °C and maximum metabolic rates (MMR) were up to 20% higher at 20 °C. We found evidence of active metabolic compensation in the southern population from 5 °C to 15 °C (Q10 < 2), but not in the northern population. Taken together, our results indicate differences in metabolic plasticity between the northern and southern populations of spotted seatrout and provide a mechanistic basis for predicting population-specific responses to climate change.

The lateral line system is a mechanosensory organ found in all fish species and located on the skin or in subdermal canals. The basic functional units are superficial and canal neuromasts, which are involved in hydrodynamic sensing and cohesion in schooling fish. Yellow-eyed mullet ( Aldrichetta forsteri) are an obligate schooling species found commonly in shallow coastal areas of New Zealand and Australia. Schooling is a fundamental part of their behavioural repertoire, yet little is known about the structure or functionality of the lateral line in this species. We used scanning electron microscopy to characterise the morphology of trunk superficial neuromasts. We then took a multi-sensory approach and conducted behavioural experiments comparing school structure in groups of fish with and without fully functioning lateral lines, under photopic and scotopic conditions. A highly developed hydro-sensing system exists on the trunk of yellow-eyed mullet consisting of superficial neuromasts containing hundreds of hair cells aligned, with respect to their most sensitive axis, in a rostrocaudal direction. Without functioning superficial neuromasts, schooling behaviour was disrupted under both photopic and scotopic conditions and the ability to detect stationary objects decreased. Results highlight the importance of this component of the lateral line system to schooling behaviour. [ABSTRACT FROM AUTHOR]

A total of 21 juvenile Cape stumpnose ( Rhabdosargus holubi) were tagged with internal acoustic transmitters in the lower, middle and upper reaches of the Kowie Estuary, South Africa. The movements of all fishes were continually monitored for five months using 22 stationary data-logging acoustic receivers, positioned along the length of the estuary. Diel and tidal cycles were identified in the movements of several individual R. holubi; however the lack of extensive movements for most individuals emphasised high residency of the species to particular sections of the estuary. River inflow and water temperature significantly affected the movement behaviour of most tagged R. holubi. Periods of increased freshwater inflow and rising riverine temperatures prompted certain individuals to shift their position downstream, while reduced sea temperatures in the lower reaches prompted certain individuals to shift their position further upstream from the mouth. Given the predicted effects of climate change in the study region, which include increased river inflow due to catchment rainfall and decreased sea temperatures due to ocean upwelling, these results suggest that R. holubi may be sensitive to the environmental effects of global warming and that the distribution and movement behaviour of this species in southern African estuaries is likely to be affected as climate change proceeds. [ABSTRACT FROM AUTHOR]