Benthic-feeding Fish Research Articles

Coral reef recovery in a remote and large marine protected area is resilient to cascading trophic interactions

Large marine protected areas (MPAs) will likely multiply worldwide to address accelerating biodiversity loss. Coral reefs are an especially at-risk ecosystem, but our understanding of whether and how large MPAs will benefit reef recovery from disturbances remains limited. Here, we evaluate how fishes influence coral reef recovery and if there are cascading trophic interactions in the fish community that influence recovery. We combine i) a meta-analysis of previous research evaluating how fishes affect coral reef succession, ii) field surveys of sharks, fishes, and benthic cover, and iii) a 2.5-year coral recruitment experiment of caged, uncaged, and partially caged settlement tiles in a remote and large MPA, in the Chagos Archipelago. In both our meta-analysis and field experiment, we found variable effects of fishes on coral recruitment with no overall significant effect, but strong control by fishes on the developing benthic communities, where fishes promote crustose coralline algae and reduce macroalgae. Within the Chagos, fishes had a positive effect on corals in protected microhabitats but a negative effect on exposed surfaces, leading to an overall neutral effect from fishes. Although mesopredatory fish abundance was negatively correlated with shark abundance, these top-down effects did not cascade down the food web through herbivores and corallivores to coral recruitment and benthic succession. Thus, our results suggest that within this large MPA, herbivores are important in limiting algae during recovery and there are compensatory responses to the loss of benthic feeding fishes and sharks, with implications for coral reef persistence in the face of global change.

The wash zone and habitat use among three benthic fish species in stratified lakes

AbstractMixing processes in lakes are important in determining sedimentation zones and in setting the so‐called “wash zone”, the area of lake bottom in contact with an oscillating thermocline during wind‐driven internal seiche events. The wash zone also aligns with a sharp change in sediment roughness and hardness. Taken together, these rapid changes in temperature and sediment indicate that the wash zone is a distinctive ecotone in stratified lakes. Depth stratified randomised netting was used to develop count‐based habitat use models for three common benthic fish species as a function of depth or temperature covariates. Using data from two lakes with quite different wash zone depths, we show the wash zone to describe fish habitat for two of three benthic fish species by utilising the top 50% of estimated fish abundance as an indicator of habitat use. White sucker (Catostomus commersoni) habitat use was within the boundaries of the wash zone. Lake whitefish (Coregonus clupeaformis) habitat was adjacent and within the wash zone. Longnose sucker (C. catostomus) habitat use was in the deep areas of lakes dominated by sediment focusing and did not overlap white sucker. Lake whitefish habitat use overlapped both catostomids, but peak abundance of both lake whitefish and white sucker overlapped pointing to potential interactions between these species. Smaller lakes have less vigorous mixing processes and a narrower wash zone, so with a decline in lake size the likely area of the wash zone as habitat for benthic feeding fish would become smaller.

Socio-ecological systems modelling of coastal urban area under a changing climate – Case study for Ubatuba, Brazil

Understanding the complex dynamics between society and nature is a critical contribution of ecological modelling. Integrated views of human-nature relations as well as tools and frameworks for studying these relations are gaining ground. A socio-ecological systems (SES) perspective therefore embraces both social and environmental factors that uses nonlinearities, feedbacks, models, and multi-level networks for understanding and studying those phenomena. When undesired drivers as climate change are also taken into account, the most urgent question is how these critical socio–ecological systems will behave given the stresses they endure. This work had the objective of creating a new simulation of a coastal SES from Brazil that is able to integrate several climatic and social variables through a dynamic and coupled model, and forecast its behavior in the future according to scenarios. Specifically, a systems dynamics simulation model using MIMES (Multiscale Integrated Model of Ecosystem Services) was developed for Ubatuba, a coastal city highly dependent and influenced by tourism. Results showed good correspondence between the model and the data when testing several environmental inputs (wind speed and direction, cloud cover, sea surface temperature, precipitation patterns). The model simulated the population dynamics of 15 biological groups from 2010 to 2100 under different scenarios. Climate change will reduce most of populations in a range from −0.13% (± 0.0%) to −10.31% (± 0.0%). There are groups where the influence of climate change is not significant (Bivalve, Brachyuran, pelagic feeding fish and benthic feeding fish) with variations from 0 to 2% and others with moderate significance (Phytoplankton, Zooplankton, and Enterococcus) with variations >2%. Tourists reacting to water quality degradation is very relevant in Enterococcus population (with a reduction of 34%). Results show the urban activities strongly influencing the biological populations and that these impacts depend on the scenario context. This suggests a policy that limits the number of tourists and increases the water quality at the same time. Therefore, the model's spatial simulation of this complex socio-ecological system can be used to develop an integrative decision-making tool to help the city manage its natural capital and adapt to its changes.

Sediment Disturbance Negatively Impacts Methanogen Abundance but Has Variable Effects on Total Methane Emissions.

Methane emissions from aquatic ecosystems are increasingly recognized as substantial, yet variable, contributions to global greenhouse gas emissions. This is in part due to the challenge of modeling biologic parameters that affect methane emissions from a wide range of sediments. For example, the impacts of fish bioturbation on methane emissions in the literature have been shown to result in a gradient of reduced to enhanced emissions from sediments. However, it is likely that variation in experimental fish density, and consequently the frequency of bioturbation by fish, impacts this outcome. To explore how the frequency of disturbance impacts the levels of methane emissions in our previous work we quantified greenhouse gas emissions in sediment microcosms treated with various frequencies of mechanical disturbance, analogous to different levels of activity in benthic feeding fish. Greenhouse gas emissions were largely driven by methane ebullition and were highest for the intermediate disturbance frequency (disturbance every 7 days). The lowest emissions were for the highest frequency treatment (3 days). This work investigated the corresponding impacts of disturbance treatments on the microbial communities associated with producing methane. In terms of total microbial community structure, no statistical difference was observed in the total community structure of any disturbance treatment (0, 3, 7, and 14 days) or sediment depth (1 and 3 cm) measured. Looking specifically at methanogenic Archaea however, a shift toward greater relative abundance of a putatively oxygen-tolerant methanogenic phylotype (ca. Methanothrix paradoxum) was observed for the highest frequency treatments and at depths impacted by disturbance (1 cm). Notably, quantitative analysis of ca. Methanothrix paradoxum demonstrated no change in abundance, suggesting disturbance negatively and preferentially impacted other methanogen populations, likely through oxygen exposure. This was further supported by a linear decrease in quantitative abundance of methanogens (assessed by qPCR of the mcrA gene), with increased disturbance frequency in bioturbated sediments (1 cm) as opposed to those below the zone of bioturbation (3 cm). However, total methane emissions were not simply a function of methanogen populations and were likely impacted by the residence time of methane in the lower frequency disturbance treatments. Low frequency mechanical disruption results in lower methane ebullition compared to higher frequency treatments, which in turn resulted in reduced overall methane release, likely through enhanced methanotrophic activities, though this could not be identified in this work. Overall, this work contributes to understanding how animal behavior may impact variation in greenhouse gas emissions and provides insight into how frequency of disturbance may impact emissions.

Changes in the population structure and life history associated with long-term intense fishing of the Argentinian croaker Umbrina canosai in southern Brazil

Identifying changes in the population structure and dynamics for fish stocks is important to support its management. Data obtained from 1976 to 2019 allowed to follow up long more than four decades the changes in the population structure and life-history of Umbrina canosai, an intensely exploited demersal sciaenid fish in southern Brazil. Intense fishing caused the truncation of the length/age structure with the loss of most of the bigger/older fishes and the sex ratio change, with increasing frequencies of males. A considerable increase in individual growth was observed and attributed to the lower competition for food due to the reduction in the density of the overall coastal benthic-feeding fish community caused by intense fishing. The large increase in the mortality and the exploitation rate resulted in a drastic decrease in the reproductive potential despite some anticipation in the sexual maturation. Despite the adaptative response to intense fishing, the high exploitation rates and the drastic reduction of the spawning potential ratio in recent years, are clear evidences that U. canosai could be reaching its adaptive capacity for resilience. Therefore, an urgent necessity for a drastic reduction of the fishing mortality to avoid the economic collapse of the fishery is required.

Probing the contamination characteristics, mobility, and risk assessments of typical plastic additive–phthalate esters from a typical coastal aquaculture area, China

Contamination characteristics, equilibrium partitioning and risk assessment of phthalate esters (PAEs) were investigated in seawater, sediment and biological samples collected from the Xiangshan Bay area during an annual investigation between January and November 2019. PAE concentrations detected in the mariculture environment in surface seawater, sediment, and biological samples were 172–3365 ng/L, 190–2430 μg/kg (dry weight [dw]), and 820–4926 μg/kg (dw), respectively. The dominant congeners in different media included di-n-butyl phthalate (DnBP), diisobutyl phthalate (DiBP), and di(2-ethylhexyl) phthalate (DEHP). The inner bay and the bay mouth were the gathering area of PAEs and heavily influenced by the mariculture activities, river inputs, and anthropogenic activities. The bioaccumulation of PAEs demonstrated benthic feeding fishes with relatively high trophic levels concentrated high levels of phthalates. The mobility of PAEs in sediment–seawater showed that the transfer tendency of low-molecular weight species was from the sediment to the water, which was in contrast with those of high-molecular weight PAEs. DEHP, DiBP and DnBP had various degrees of ecological risks in the aquatic environment, whereas only the DiBP posed potential risks in sediments. The current assessment of carcinogenic and noncarcinogenic risks posed by fish consumption were within acceptable limits for humans.

Suspect screening of pharmaceuticals in fish livers based on QuEChERS extraction coupled with high resolution mass spectrometry

The presence of pharmaceuticals and personal care products (PPCPs) in aquatic environments is of increasing concern due to the presence of residues in fish and aquatic organisms, and emerging antibiotic resistance. Wastewater release is an important contributor to the presence of these compounds in aquatic ecosystems, where they may accumulate in food webs. The traditional environmental surveillance approach relies on the targeted analysis of specific compounds, but more suspect screening methods have been developed recently to allow for the identification of a variety of contaminants. In this study, a method based on QuEChERS extraction – using acetonitrile/water mixture as solvent and PSA/C18 for sample clean-up – was applied to identify pharmaceuticals and their metabolites in fish livers. Both target and suspect screening workflows were used and fish were sampled upstream and downstream of wastewater treatment plants from the Scioto River, Ohio (USA). The method performed well in terms of extraction of some target PPCPs, with recoveries generally above 90%, good repeatability (<20%), and linearity. Based on target analysis, lincomycin and sulfamethoxazole were two antibiotics identified in fish livers at average concentrations of 30.3 and 25.6 ng g−1 fresh weight, respectively. Using suspect screening, another antibiotic, azithromycin and an antidepressant metabolite, erythrohydrobupropion were identified (average concentrations: 27.8 and 13.8 ng g−1, respectively). The latter, reported, to the best of our knowledge, for the first time in fish livers, was also found at higher concentrations in fish livers sampled downstream vs. upstream. The higher frequency of detection for azithromycin in benthic feeding fish species (63%) as well as clusters identified between different foraging groups suggest that foraging behavior may be an important mechanism in the bioaccumulation of PPCPs. This study shows how suspect screening is effective in identifying new contaminants in fish livers, notably using differential analysis among different spatially distributed samples.

Changes to water quality and sediment phosphorus forms in a shallow, eutrophic lake after removal of common carp (Cyprinus carpio)

ABSTRACT Pickerel Lake (Minnesota, USA) is a shallow, polymictic lake that has had eutrophication problems for decades. Although excess nutrient loading has been a problem in the past, the dominance of common carp (Cyprinus carpio) was considered to be a substantial factor driving and sustaining eutrophic conditions. To remove carp and restore the fish community, the lake was treated with rotenone in late 2009 and then restocked with native species. All water quality variables improved after carp removal, with mean values (May–Sep) for chlorophyll a, total phosphorus, and turbidity decreasing by 80% to 93% and Secchi disk transparency increasing nearly 600% when comparing means of pre- to post-treatment years. Macrophyte coverage also improved, from means of 4.6% before treatment to 90% after treatment, indicating a shift from an algal- to a macrophyte-dominated system. Sediment phosphorus (P) storage increased significantly after carp removal as well, with labile (releasable) forms of P increasing in the upper 10 cm of sediment in all cores (n = 7). The decrease in water column P equaled the increase in labile sediment P forms after treatment, indicating carp were a key driver of P transport from sediment to water. The results of this study indicate that an ecological (i.e., both abiotic and biotic) approach is needed when managing eutrophic lakes because management of nutrients alone will not likely be adequate to restore water quality in systems dominated by carp or other large benthic feeding fish.

The Role of Top-Down and Bottom-Up Control for Phytoplankton in a Subtropical Shallow Eutrophic Lake: Evidence Based on Long-Term Monitoring and Modeling

Lake ecosystems are exposed to a range of anthropogenic pressures, particularly eutrophication, and in some cases also stocking and/or overfishing of top-predator fish species, all factors that have implications for the food web structure and which could lead to dominance of nuisance cyanobacteria. Restoration of degraded lakes demands insight into the relative role of top-down for bottom-up regulating forces. While knowledge about these forces in temperate lakes is extensive, comparatively little is known of their role in subtropical lakes where the importance of herbivorous and benthic feeding fish is higher. Here, we analyzed a long-term monitoring data set on subtropical, shallow Lake Taihu, China, and applied random forests regression to examine how phytoplankton was related to environmental variables and biotic assemblages. Our results indicate that the biomass and density of phytoplankton increased with increasing biomass of benthivorous and zooplanktivorous fish and decreased with increases in ammonium concentrations, the nitrogen to phosphorus ratio, and zooplankton biomass, while the response to climate fluctuations and changes in the biomass of piscivores was weak. Effects of higher trophic levels explained as much of the variance in phytoplankton biomass as did nutrients and climatic factors. Moreover, the remarkably reduced ratio of zooplankton to phytoplankton biomass and the decline in cladoceran individual biomass emphasized the increasing importance of top-down control in regulating the phytoplankton following extensive stocking. Our findings offer insight into how fish management may be combined with catchment-level restoration measures to conserve and enhance water quality.

Distribution of phthalate esters in air, water, sediments, and fish in the Asan Lake of Korea

Phthalate esters (PEs) are the most commonly used plasticizers and one of the endocrine disrupting chemicals (EDCs) which are extensively present in various environment. Therefore, it is important to examine the levels and distribution of phthalates in multimedia environment. This study investigated the seasonal and spatial variation of 14 PEs in air, water, sediments, and fish in the Asan Lake. Asan Lake is one of the largest artificial lakes in Korea, and is surrounded by industrial complex and farmlands. The PEs were found to be present throughout the study area. The mean concentration of total PEs (∑14 PEs) was 3.92–33.09 ng/m3 in air, not detected (n.d.)-2.29 μg/L in water, 3.6–8973 μg/kg dry weight (dw) in sediment, and n.d.-1081 μg/kg dw in fish, respectively. The most frequently detected phthalate in the samples was di(2-ethylhexyl) phthalate (DEHP), and followed by di-n-butyl phthalate (DBP). The concentrations of PEs in water and sediment samples tended to decrease moving downstream of Asan Lake. Bioaccumulation of PEs showed that benthic feeding fish such as crucian carp or skygager contained higher levels of DEHP. Partitioning of DEHP and DBP between water and sediment was calculated using paired sediment/water samples and fugacity fraction (ff). High ff value (ff = 0.89 ± 0.1) of DBP and low ff value of DEHP (ff = 0.24 ± 0.1) confirmed that DEHP is the most abundant PEs in the sediment, and DBP is the second most abundant PEs except DEHP in water. Our results can provide important information of the distribution and behavior of PEs in the lake environment.

Trait-based predation suitability offers insight into effects of changing prey communities.

Increasing environmental pressures and human impacts are reshaping community structures and species interactions throughout all trophic levels. The morphological and behavioural characteristics of species communities contain key ecological information on why prey species appear attractive to predators but are rarely applied when exploring predator-prey (PP) relationships. Expanding our knowledge on how changing prey communities can alter the food resource suitability (RS) for predators is vital for understanding PP dynamics in changing ecosystems. Detailed predator diet data are commonly restricted to commercially important species and often not available over long temporal scales. To find out whether structural changes of prey communities impact the food RS for predator communities over space and time, we apply a novel framework to describe and interpret changes in predator diet-suitability based on predation-relevant traits of prey. We use information on described feeding links from the literature to compile the prey spectrum for each predator and subsequently translate the prey-species into a prey-trait spectrum. For each predator, we then calculate a frequency-based prey-trait affinity score and relate it to the available food resource pool, the community weighted means of prey traits, resulting in a prey-suitability measure. We aim to reveal whether a described multi-decadal change in the community structure of zoobenthos had an impact on the food suitability for the benthic-feeding fish in a coastal system of the Baltic Sea. We assess the direction of change in resource quality from the perspective of benthic-feeding fish and describe predator-specific responses to examine which species are likely to profit or be disadvantaged by changes in their prey spectrum. Furthermore, we test the relationship between functional diversity of prey communities and food suitability for predators, and whether predation linkage-structures are affected through prey community-changes. Our results show that changes in zoobenthic communities had a positive effect on the food suitability for most benthic-feeding fish, implying more suitable food resources. Species-specific responses of predators suggest varying plasticity to cope with prey assemblages of different trait compositions. Additionally, the functional diversity of zoobenthos had a positive effect on the food suitability for predator fish. The changing trait compositions of prey influenced the PP linkage-structure, indicating varying specialisation of benthic feeding fish towards available food resources. Our findings suggest that changing morphological characteristics of prey can impact food RS features for its predators. This approach enables long-term evaluation of prey quality characteristics where no detailed diet data is available and allows for cross-system comparison as it is not relying on taxonomic identities per se.

Successful restoration of a tropical shallow eutrophic lake: Strong bottom-up but weak top-down effects recorded

Fish manipulation has been used to restore lakes in the temperate zone. Often strong short-term cascading effects have been obtained, but the long term-perspectives are less clear. Fish manipulation methods are far less advanced for warm lakes, and it is debatable whether it is, in fact, possible to create a trophic cascade in warm lakes due to the dominance and high densities of fast-reproducing omnivorous fish. However, removal of benthic feeding fish also reduce disturbance of the sediment, which not only affects the nutrient level but also the concentration of suspended organic and inorganic matter with enhanced water clarity and potentially better growth conditions for submerged macrophytes. We conducted a biomanipulation experiment in one of the basins in Chinese Huizhou West Lake that have remained highly turbid after extensive nutrient loading reduction. Another basin was used as control (control-treatment pairing design). Removal of a substantial amount of plankti-benthivorous fish was followed by planting of submerged macrophytes and stocking of piscivorous fish. We found strong and relatively long-lasting effects of the restoration initiative in the form of substantial improvements in water clarity and major reductions in nutrient concentrations, particularly total phosphorus, phytoplankton and turbidity, while only minor effects were detected for crustacean zooplankton grazers occurring in low densities before as well as after the restoration. Our results add importantly to the existing knowledge of restoration of warm lakes and are strongly relevant, not least in Asia where natural lakes frequently are used extensively for fish production, often involving massive stocking of benthivorous fish. With a growing economy and development of more efficient fish production systems, the interest in restoring lakes is increasing world-wide. We found convincing evidence that fish removal and piscivores stocking combined with transplantation of submerged macrophytes may have significant effects on water clarity in warm shallow lakes even if the zooplankton grazing potential remains low, the latter most likely as a result of high predation on the zooplankton.

The food web positioning and trophic niche of the non-indigenous round goby: a comparison between two Baltic Sea populations

The food web positioning of the non-native round goby (Neogobius melanostomus Pallas, 1814) was studied in a new invasive population in Mariehamn, Aland Islands (northern Baltic Sea). The trophic position and isotopic niche space was compared to other benthic-feeding fish species in the same habitat. The trophic position (TP) was estimated based on stable isotope analysis of carbon (13C:12C) and nitrogen (15N:14N) ratios and compared to that of an established invasive population in Hel, Gulf of Gdansk (southern Baltic Sea). Ontogenetic changes in isotope signatures were evaluated with a regression analysis and compared between the two populations. The round goby positioned as a second-order consumer on the third trophic level among other benthic-feeding fish. It showed a similar trophic position and significant isotopic niche overlap with large perch. The trophic position of round gobies in Mariehamn is significantly higher than in Hel, likely due to different prey items. Furthermore, the ontogenetic patterns differ between the two invasive populations, also suggesting differing resource and habitat availability and levels of intraspecific competition between areas.

Change in the rocky reef fish fauna of the iconic Poor Knights Islands Marine Reserve in north-eastern New Zealand over 4 decades

Marine reserves exhibit increases in targeted fish species, but long-term effects on biodiversity are poorly understood. Factors other than reserve status may affect decadal changes, including environmental change. We examined the fish fauna at the iconic Poor Knights Islands over 4 decades (1974–2016) before and after implementation of a no-take marine reserve in 1998. We document a substantial increase in commercially and recreationally targeted Chrysophrys auratus, which was virtually absent before 1994 but by 2016 had reached up to 11 fish per 500m2 (220 per hectare). There were also large changes to the fish community, including the decline of subtropical and coastal wrasses, some species with no change and others that increased significantly. Many declines occurred &gt;20 years before the arrival of abundant C. auratus, suggesting the changes do not represent a trophic cascade. Furthermore, this normally benthic-feeding fish has adopted a mid-water foraging behaviour targeting planktivorous fish. The increase in C. auratus appears to be linked both to reserve status and catch regulations in the wider region. Overall, the data point to long-term environmental fluctuations from the late 1970s having a negative effect on the abundance of more than half the reef fish species at these islands.

Foraging Fish as Zoogeomorphic Agents: An Assessment of Fish Impacts at Patch, Barform, and Reach Scales

AbstractFlume studies have demonstrated that foraging by fish can modify the structure and topography of gravel substrates, thereby increasing particle entrainment probabilities and the amount of sediment mobilized during subsequent experimental high flows. However, the zoogeomorphic impact of benthic foraging has not previously been investigated in the field. This paper reports field experiments that examined the nature and extent of disturbance of riverbed gravels by foraging fish, predominately Cyprinids, at patch, riffle, and reach scales and complementary ex situ experiments of the impacts on bed stability. At patch scale, benthic feeding fish displaced particle sizes ≤90 mm in diameter, increased bed surface microtopography and grain protrusion, and loosened surface structures. Although enhanced mobility was expected from these structural changes, foraging also caused localized coarsening of sediments, and the ex situ experiments recorded significantly reduced grain entrainment, bedload flux, and total transported mass from foraged patches. Foraging disturbed bed materials at all 12 riffles in the study reach and, on average, disturbed 26.1% of riffle area per 24 h feeding period. These findings demonstrate for the first time that foraging fish, which are widespread and feed perennially, can act as zoogeomorphic agents in rivers, affecting grain‐size distributions and bed material structure, with potential implications for bed stability and bedload transport at reach and river scales. Whether fish increase or reduce bed mobility is probably dependent on a host of factors, including the net effects of both structural disturbance and biogenic particle sorting, as these affect entrainment stresses under subsequent competent flows.

Using biochemical and isotopic tracers to characterise organic matter sources and their incorporation into estuarine food webs (Rufiji delta, Tanzania)

ABSTRACTFatty acid biomarkers and stable isotope signatures were used to identify the sources of particulate and sedimentary organic matter and its input into the food web through the dominant consumer within the mangrove-dominated Rufiji estuary, Tanzania. Specific fatty acids were used to identify the preferred basal sources of dominant fauna (i.e. filter feeder bivalves, snails, crabs, shrimps, and three fish species), and their presence in the water and sediment samples in the estuary. Both fatty acid and stable isotope results revealed that food web in the Rufiji estuary depended on a variety of carbon sources (mangroves, allochthonous terrestrial inputs, macroalgae, and phytoplankton), contributing to a different degree into the diets of primary consumers and members of near-shore fish, but none of them were obligatory for the survival of these species. The δ15N values of major primary producers and consumers/predators revealed a trend for δ15N enrichment with increasing trophic level. The ratio of docosahexaenoic acid to eicosapentaenoic acid (DHA:EPA) decreased from pelagic to benthic feeding fish. This indicated that fish with different feeding modes derived their fatty acids from different primary sources of nutrition, and suggested that the DHA:EPA ratio may be a useful indicator of feeding mode.

Elucidating the Behavior of Cyclic Volatile Methylsiloxanes in a Subarctic Freshwater Food Web: A Modeled and Measured Approach

Cyclic volatile methylsiloxanes (cVMS) are used in personal care products and emitted to aquatic environments through wastewater effluents, and their bioaccumulation potential is debated. Here, a new bentho-pelagic version of the ACC-HUMAN model was evaluated for polychlorinated biphenyls (PCBs) and applied to cVMS in combination with measurements to explore their bioaccumulation behavior in a subarctic lake. Predictions agreed better with measured PCB concentrations in Arctic char (Salvelinus alpinus) and brown trout (Salmo trutta) when the benthic link was included than in the pelagic-only model. Measured concentrations of decamethylcyclopentasiloxane (D5) were 60 ± 1.2 (Chironomidae larvae), 107 ± 4.5 (pea clams Pisidium sp.), 131 ± 105 (three-spined sticklebacks: Gasterosteus aculeatus), 41 ± 38 (char), and 9.9 ± 5.9 (trout) ng g-1 wet weight. Concentrations were lower for octamethylcyclotetrasiloxane (D4) and dodecamethylcyclohexasiloxane (D6), and none of the cVMS displayed trophic magnification. Predicted cVMS concentrations were lower than measured in benthos, but agreed well with measurements in fish. cVMS removal through ventilation was an important predicted loss mechanism for the benthic-feeding fish. Predictions were highly sensitive to the partition coefficient between organic carbon and water (KOC) and its temperature dependence, as this controlled bioavailability for benthos (the main source of cVMS for fish).

A First Survey of Metazoan Parasites in the Fishes of Lake Powell, Utah

Abstract. Lake Powell (Colorado River drainage, Utah and Arizona, USA) is an important and unique fishery comprising several nonnative fishes. There are no previous studies of the parasites of the fishes of Lake Powell. We provide a general survey of the metazoan parasites found in the numerically dominant fish species of the reservoir. We collected and surveyed for parasites in 236 fishes of 8 species. We found 832 parasites comprising 13 species. All of the parasite species we found are widespread throughout North America and other parts of the world. Six of the 13 species of parasites we found have been documented previously in the Colorado River system. In general, benthic-feeding fishes exhibited higher parasite richness and intensity compared to pelagic-feeding fishes. This study serves as a baseline for parasite community studies in Lake Powell and can provide a comparison for future studies.

Spatial and Temporal Variability in Benthic Invertebrate Assemblages in Upper Klamath Lake, Oregon

Abstract Upper Klamath Lake (UKL) in southern Oregon has experienced declines in water quality due to excessive nutrient loading. This has led to annual cyanobacterial blooms, primarily of Aphanizomenon flos-aquae (AFA). Benthic invertebrates are important food resources for benthic feeding fishes; however, they can increase autochthonous nutrient cycling in lakes and as a result might be contributing to poor water quality in UKL. This study determined the density and taxonomic richness of benthic invertebrate assemblages in three geographic regions (north, central, and south) and three habitats (littoral, open-water and trench) across UKL. Sediment composition and water quality were also characterized at each of the 21 benthic invertebrate collection sites. Three sampling trips were made from May–July 2013. Mean lake-wide invertebrate density was 12 617 ± 7506 individuals m-2 (n = 63, based on 189 Ekman grabs) with oligochaetes, chironomids, and leeches representing 97% of all individuals. Mean invertebr...

鲢鳙鱼养殖小型水库底栖动物群落季节动态

PDF HTML阅读 XML下载 导出引用 引用提醒 鲢鳙鱼养殖小型水库底栖动物群落季节动态 DOI: 10.5846/stxb201607271533 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 湖北省科技计划研究与开发项目（2013BBA049）；江西省教育厅青年基金项目（GJJ13018）；南昌大学鄱阳湖环境与资源利用教育部重点实验室开放基金（13006457） Seasonal dynamics of zoobenthos communities in a small reservoir stocked with silver and bighead carp Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:底栖动物是鱼类重要的天然饵料，评估水体中底栖动物的现存量可以指导渔业生产中鱼类的放养数量。为了探究淡水生态养殖水库中底栖动物群落的季节动态，于2013年4月、7月、10月和2014年1月对三河水库的底栖动物群落进行了调查分析。研究共采集到7个属的底栖动物，隶属于颤蚓科、摇蚊科和蠓科，未采集到软体动物。相对重要性指数 （IRI） 计算结果表明，菱跗摇蚊属 Clinotanypus （IRI=7136）、颤蚓属 Tubifex （IRI=6734） 和尾鳃蚓属 Branchiura （IRI=1384） 是优势类群，分别占总捕获数量的34.26%、50.38%和10.96%。不同季节之间底栖动物的总密度和生物量差异显著 （P < 0.05），均为冬季 > 春季 > 夏季 > 秋季。冬季总密度 （4100个/m2） 和总生物量 （10.14 g/m2） 最高，春季 （1446个/m2； 1.07 g/m2） 次之，夏季 （579个/m2； 0.66 g/m2） 较低，秋季 （492个/m2； 0.64 g/m2） 最低。非度量多维尺度分析 （MDS） 和群落相似性分析表明底栖动物群落结构季节差异显著 （P =0.001），2013年三河水库的底栖动物群落可明显划分为3个：春季群落、夏秋季群落和冬季群落。皮尔森相关分析表明，底栖动物总密度与溶氧和营养盐呈正相关关系，与其他水理化因子呈显著负相关关系 （P < 0.05）。冗余分析表明，氨氮、盐度、pH和浊度是三河水库底栖动物群落季节差异的显著影响因子（P < 0.05），总氮对底栖动物群落的季节差异具有边缘显著影响 （P =0.08）。 Abstract:Zoobenthos is an important natural food resource for fishes. Assessing the standing crop of zoobenthos in water bodies can provide the guideline for stocking fishes in fishery production. To explore the seasonal dynamics of zoobenthic communities in freshwater aquaculture reservoirs, investigations were conducted in April, July, and October 2013, and January 2014, to determine the composition of zoobenthic communities in the Sanhe Reservoir. The relationships between zoobenthic communities and environmental factors (water temperature, pH, turbidity, salinity, dissolved oxygen, chlorophyll a, NH4+-N, NO3- -N, total nitrogen, and total phosphorus) were analyzed. In this study, seven genera of zoobenthos belonging to Tubificidae, Chironomidae, and Ceratopogouidae were detected. The results of the index of relative importance (IRI) showed that Clinotanypus (IRI=7136), Tubifex (IRI=6734), and Branchiura (IRI=1384) were dominant groups, which accounted for 34.26%, 50.38%, and 10.96% of total abundance, respectively. The total density and biomass of zoobenthos significantly varied among seasons (P < 0.05), and both were highest in winter (4100 ind./m2 , 10.14 g/m2), followed by spring (1446 ind./m2 , 1.07 g/m2), and summer (579 ind./m2 , 0.66 g/m2), and were lowest in autumn (492 ind./m2 , 0.64 g/m2 , respectively). The zoobenthic communities in the Sanhe Reservoir mostly consisted of oligochaetes and chironomid larvae, which exhibited characteristics of higher density and lower biomass. Tubifex was the most dominant group in spring. Tubifex and Branchiura were dominant groups in summer and autumn. Chironomidae and Tubifex were dominant groups in winter. Significant differences in zoobenthic communities among seasons were found by non-metric multi-dimensional scaling (MDS) and similarity analysis (P =0.001). Zoobenthic communities in the Sanhe Reservoir showed three temporal communities, i.e., spring community, summer-autumn community, and winter community. Pearson correlation analysis indicated that total density of zoobenthos was positively correlated with dissolved oxygen and nutrients. However, the total density of zoobenthos had significant negative correlations with water temperature, pH, salinity, turbidity, and chlorophyll-a content (P < 0.05). Redundancy analysis suggested that NH4+-N, salinity, pH, and turbidity were important factors, which had significant effects on seasonal variation of zoobenthic communities (P < 0.05). Total nitrogen concentration had marginally significant effects on seasonal differences of zoobenthic communities (P =0.08). In the pelagic zones of the small reservoir stocked with higher density of fishes, organism deposition resulted in a narrower habitat for the distribution of molluscs, such as shellfish and snails. Therefore, the composition of benthic fauna was dominated by oligochaetes and insect larvae. The differences in predator pressure on zoobenthos caused by fishes in different seasons had direct effects on the seasonal dynamics of zoobenthic communities in the fish stocked reservoir. In addition, the distribution of some benthic feeding fish, such as Pelteobagrus fulvidraco, might lead to the decrease in zoobenthos density in the reservoir. 参考文献 相似文献 引证文献