Changes In Fish Community Structure Research Articles

Interplay of management and environmental drivers shifts size structure of reef fish communities.

Countries are expanding marine protected area (MPA) networks to mitigate fisheries declines and support marine biodiversity. However, MPA impact evaluations typically assess total fish biomass. Here, we examine how fish biomass disaggregated by adult and juvenile life stages responds to environmental drivers, including sea surface temperature (SST) anomalies and human footprint, and multiple management types at 139 reef sites in the Mesoamerican Reef (MAR) region. We found that total fish biomass generally appears stable across the region from 2006 to 2018, with limited rebuilding of fish stocks in MPAs. However, the metric of total fish biomass masked changes in fish community structure, with lower adult than juvenile fish biomass at northern sites, and adult:juvenile ratios closer to 1:1 at southern sites. These shifts were associated with different responses of juvenile and adult fish to environmental drivers and management. Juvenile fish biomass increased at sites with high larval connectivity and coral cover, whereas adult fish biomass decreased at sites with greater human footprint and SST anomalies. Adult fish biomass decreased primarily in Honduran general use zones, which suggests insufficient protection for adult fish in the southern MAR. There was a north-south gradient in management and environmental drivers, with lower coverage of fully protected areas and higher SST anomalies and coastal development in the south that together may undermine the maintenance of adult fish biomass in the southern MAR. Accounting for the interplay between environmental drivers and management in the design of MPAs is critical for increasing fish biomass across life history stages.

Monitoring of multiple fish species by quantitative environmental DNA metabarcoding surveys over two summer seasons.

Periodic monitoring can provide important information for the protection of endangered fish, sustainable use of fishery resources and management of alien species. Previous studies have attempted to monitor fish using non-invasive environmental DNA (eDNA) technology, generally employing quantitative PCR to quantify the eDNA concentration. However, the throughput was limited. High-throughput metabarcoding technology can detect the DNA of multiple species simultaneously in a single experiment but does not provide sufficient quantification. In this study, we applied a quantitative metabarcoding approach to simultaneously quantify the eDNA concentration of an entire fish assemblage in a small reservoir over two summer seasons. Traditional surveys were also conducted to investigate the individuals of fish. The eDNA concentrations were quantified using quantitative metabarcoding, and the fish species detected using this approach were highly consistent with the results of traditional fish monitoring. A significant positive relationship was observed between the eDNA concentration and fish species abundance. Seasonal changes in fish community structure were estimated using eDNA concentrations, which may reveal the activity seasons of different fish. The eDNA concentrations of different fish species peaked at different water temperatures, reflecting the differential responses of fish species to this environmental factor. Finally, by detecting outlier eDNA concentrations, the spawning activities of 13 fish species were estimated, 12 of which were roughly consistent with the current knowledge of fish spawning periods. These results indicate that quantitative eDNA metabarcoding with dozens of sampling times is useful for the simultaneous ecological monitoring of multiple fish species.

Analysis of short-term and local scale variations in fish community structure in Dachen Island waters

Understanding the changes in community structure of fishery resources in island reef waters is crucial for effective fishery resource management, as these waters constitute a critical link in maintaining the sustainable development of offshore fishery resources. The study analyzed the structure of the fish community in the waters surrounding Dachen Island by using data collected during four voyage surveys conducted between September 2020 and April 2021. The study utilized co-occurrence network analysis, multiple regression trees, and functional diversity analysis to investigate the short-term and local scale changes in fish community structure. The results showed that the fish community in the waters adjacent to Dachen Island can be categorized into two groups: annual and stage-use species. The stage-use species include Scoliodon laticaudus, Trichiurus lepturus, Tetraodontidae, and others, which are used during the summer and autumn stages of bait migration. Additionally, Dasyatidae and others, which used during the winter and spring stages of reproductive migration. Furthermore, the study found that the habitats dominated by nearshore rocky habitats and distant deep habitats formed the local scale variation in community structure in island waters. The integrated analysis of species α-diversity and functional diversity provided a basis for understanding the mechanisms of biodiversity action. Our study aims to provide a theoretical framework for the development of fishery resource management strategies based on the life cycle of fish, and to serve as a reference for the prioritization of key protection areas for fishery resources in island and reef environments. Overall, the study’s findings can promote the understanding of community structure dynamics in island waters. Additionally, these findings can offer valuable insights into the restoration of habitats and the implementation of marine ranching activities in Dachen Island. Moreover, the outcomes can serve as a theoretical foundation for the development of appropriate management and conservation strategies for fisheries resources.

Evaluation of Sustainable Utilization of African Marine Fishery Resources

Sustainable utilization evaluation is the basis for ensuring the sustainable exploitation of fisheries’ resources. This paper explores the changes in the mean trophic level of African marine fish catches during a 70-year period based on the statistical data on marine fisheries’ catches in Africa from 1950–2019, provided by the FAO in, order to determine the sustainable utilization of Africa’s fishery resources. The results indicate that although the marine fishery resources of African coastal countries have great variability, their exploitation has roughly gone through the stages of under-exploitation, rapid exploitation, and over-exploitation. Currently, marine fisheries in North and Central Africa are characterized by sustainable exploitation, while East, West, and Southern Africa are in a state of overfishing. The study implicates that African countries should establish a real-time monitoring system for marine fishery resources as soon as possible in order to dynamically grasp the actual changes in fish community structure due to fishing activities, ensure transparency in management and decision making, enact marine regulations to restrict massive fishing by overseas fleets, issue fisheries licenses cautiously, adopt conservative resource conservation policies, and enforce actions to achieve sustainable fisheries development.

Variations in Fish Community Structure at the Lagoon of Yongshu Reef, South China Sea between 1999 and 2016–2019

Owing to climate change and anthropogenic stressors, the abundance and diversity of reef fishes have globally decreased. However, we know little about the long-term change in reef fishes in the South China Sea (SCS). To reveal the response of reef fishes to these threats in the SCS, based on the fish specimens at Yongshu Reef lagoon collected in 1999 and 2016–2019, this study investigated variations in fish composition and community structure. Additionally, we inferred the changes in the coral cover of Yongshu Reef based on the change of the coral cover of near Meiji Reef in the SCS, sea surface temperature (SST) in Yongshu Reef, and total annual catch of Epinephelinae from China in the SCS. We found that compared with 1999, the number of dominant species in 2016–2019 decreased. The relative dominance of the first dominant species increased from 24.46 in 1999 to 39.44 in 2016–2019. Indices of catch per unit effort, species diversity and richness declined from 1999 to 2016–2019. Community pattern changed with some species with a higher trophic level (3.7–4.5) decreased, while those with lower trophic level (2.2–4.1) increased greatly. Some species with high economic value and important ecological functions decreased or disappeared locally. Correlation analysis indicated that declining coral cover, increasing fishing and rising SST were clearly associated with changes in fish community structure at Yongshu Reef. We speculated that declining coral cover and increasing fishing had a direct impact on the degradation of fish communities at Yongshu Reef lagoon, but increasing SST had an indirect impact on that. To conserve coral reef fish, it is recommended to take rigorous measures for improving habitat and protecting resource.

Fish diversity patterns along coastal habitats of the southeastern Galapagos archipelago and their relationship with environmental variables

Coastal habitats are essential for ecological processes and provide important ecosystem services. The Galapagos archipelago has a wide diversity of ichthyofauna which preservation guarantees the functioning of the marine ecosystem. In this study, we used ecological and taxonomic indices as well as multivariate analysis to identify spatiotemporal changes in fish community structure in coastal habitats of San Cristóbal Island in the southeastern Galapagos archipelago. We analyzed how the patterns of variability were related to the abiotic conditions (substrate, sea temperature and depth) of each habitat. Nine sites affected by anthropogenic influence (fishing and tourism) representing different habitats/substrates were sampled. Underwater surveys were conducted during the warm and cold seasons in 2010 and 2011 at transects that varied in depth according to site. Artificial habitat, followed by coral and rocky habitats, had the highest diversity, evenness, and taxonomic distinctness, while mangrove habitats had the lowest values. This was related to the habitat complexity and possible anthropogenic influences. While the diversity patterns were more strongly related to the type of substrate, followed by the combination of substrate and depth, and the sea temperature had less influence. These findings were related to the ecological traits of the fish communities and their mobility between habitats. Temporal changes in fish community diversity and composition were not detected at all sites, suggesting that these species have high fidelity to their habitats and a high environmental tolerance that allows them to persist in their habitats despite strong changes in sea temperature on the Galapagos archipelago.

Deep demersal fish communities respond rapidly to warming in a frontal region between Arctic and Atlantic waters.

The assessment of climate impact on marine communities dwelling deeper than the well‐studied shelf seas has been hampered by the lack of long‐term data. For a long time, the prevailing expectation has been that thermal stability in deep ocean layers will delay ecosystem responses to warming. Few observational studies have challenged this view and indicated that deep organisms can respond exceptionally fast to physical change at the sea surface. To address the depth‐specific impact of climate change, we investigated spatio‐temporal changes in fish community structure along a bathymetry gradient of 150–1500 m between 1998 and 2016 in East Greenland. Here, the Arctic East Greenland Current and the Atlantic Irminger Current meet and mix, representing a sub‐Arctic transition zone. We found the strongest signals of community reorganizations at depths between 350 and 1000 m and only weak responses in the shallowest and deepest regions. Changes were in synchrony with atmospheric warming, loss in sea ice and variability in physical sea surface conditions both within our study region and North of the Denmark Strait. These results suggest that interannual variability and long‐term climate trends of the larger ecoregion can rapidly affect fish communities down to 1000‐m depth through atmospheric ocean coupling and food web interactions.

Determination of the Fish Community Structure of an Intertidal Rocky Zone of the Pacific Coast of Baja California Sur

The intertidal zone (also known as seashore) are transition areas between land and sea, that are greatly influenced by the tide cycle, therefore, environmental parameters, such as temperature and salinity, oscillate according to the periods in which these areas are exposed to air. Intertidal zones are highly diverse, which makes them key ecosystems for the development of sea life (both flora and fauna) exposed to drastic environmental change. The 59 visual censuses campaigns were carried out during the full moon of each month from 2015 to 2019. Temperature, salinity and dissolved oxygen were recorded during each visual census and showed variations between years. Temperature showed two distinct seasons, warm and cold. A total of 14,995 organisms were recorded, belonging to 30 species, 28 genera, 15 families, five orders and one class. Ecological indices like species richness (SR), Shannon-Wiener’s diversity (H') and Fisher’s alpha (α-Fisher) showed significant differences between years, 2015 and 2016 recorded as the most diverse years, while the lowest values were recorded in 2019. Therefore, fish communities of tide pools showed to be highly diverse, with 30 species recording similar relative abundances, and according to the BVI, only 11 species were dominant. Spatio-temporal variations of temperature, salinity and dissolved oxygen were highly correlated to changes in fish community structure, and the dominance of certain species, which are of great importance for the structure and dynamic of the tide pool communities. Therefore, the aim of the present study was to determine the fish community structure of tide pools during the low tide in the intertidal zone of a locality known as El Faro, on the west coast of La Paz, B. C. S., Mexico.

Implications of Community-Based Management of Marine Reserves in the Philippines for Reef Fish Communities and Biodiversity

Overfishing and destructive fishing practices are major threats to marine biodiversity in the Philippines, where over 1.9 million small-scale fishers are supported by these biodiverse marine communities. Nearly 50% of all marine fish capture in the Philippines is from artisanal fisheries, with much of it not reported or under-reported. Marine reserves, where fishing is prohibited have been created in many local government units to help restore and preserve this biodiversity. The success of these marine reserves is still under serious debate with effective management still representing a significant challenge. The lack of a governance system to centrally managed marine reserves has resulted in non-governmental organizations developing community-based management schemes. Using independent fisheries data from Rare’s Fish Forever program, we applied PERMANOVA, SIMPER and biodiversity index analyses to evaluate the community structure of reef fish in 20 sites within the Philippines. We analyzed the differences in fish assemblage inside and outside of these marine reserves, before and after community-based management had been implemented. We provide evidence that: (i) fish community structure changes within marine reserves after community-based management strategies are implemented; and (ii) community-based management of marine fisheries resources protects and promotes biodiversity inside, and in some cases, outside marine reserves. Variability across sites suggests that other social or ecological factors may be influencing the ability of marine reserves to fully protect biodiversity and marine resources. Small-scale fishers in the Philippines participate in mixed-catch harvests and depend on biodiversity and reef community structure for their livelihoods. Thus, this work has implications on how community-based management strategies for marine reserves and adjacent waters may be beneficial for the sustainability of small-scale fishers.

Community structure and niche breadth of some fish in Pangelang Protected Lake, Kapuas Hulu District

Ecologically, weather changes cause local deviations from regional patterns in waters. So that there will be changes in fish types and food habits.The purpose of this study was to determine changes in fish community structure, food preferences, and area of niches for each type of fish in Pangelang Protected Lake. The research was conducted using a survey method in October 2016 (low tide), June 2018 (transition) and September (flood) 2018. The results obtained: 1. Fish communities in Lake Pangelang obtained a total of 12 families, 30 genera, and 37 species. In the low tide season, there are 21 species of fish caught, 17 species of transition season and 16 types of flood during low tide. 2. In the low tide season, the fish community in Pangelang Lake is dominated by detritivorous fish. In the transitional season, the fish community in Pangelang Lake experiences changes with an increase in the union of phytoplanktivore and insectivore fish. During the flood season, the fish communities in Lake Pangelang underwent a change again where the union of herbivores that used plants increased.

Assessing Linkages Between Small Impoundments and Long-term Trajectories of Prairie Stream Fish Assemblages

Most stream fish communities have changed over time in response to common anthropogenic disturbances. Impoundments are a widespread anthropogenic stressor that can negatively impact stream fishes as they alter flow regimes, block movements, and act as fountainheads for the introduction and spread of invasive species. Recent studies, however, have reported the occurrence and reproduction of native fishes in impoundments, suggesting they might benefit some native fishes. Our primary objective was to evaluate whether impoundment construction has led to changes in fish community structure in prairie streams. To accomplish this, we compared fish occupancy in small impoundments (,5 ha) to temporal trends in stream occupancy among species to test whether species' increases in stream occupancy were related to their occupancy in impoundments. We examined stream fish communities in the Upper Cottonwood River basin, Kansas, from 1948–2018, and sampled small impoundments in 2016 and 2017. A third (32%) of fish communities in impoundments were similar to stream assemblages, whereas most impoundments (68%) were dominated by sport or bait fishes. In streams, six species showed increases in occupancy and four species showed decreases since small impoundment construction. Of the species that exhibited increased stream occupancy, five showed a positive, logistical relationship between a species' impoundment occupancy and its increase in stream occupancy. Species declining in stream occupancy experienced continued linear declines and may still be declining. Our research suggests stream fish communities have changed since impoundment construction, and are associated with locally-invasive, native species reaching a new stable state in streams accompanied by declines in other native stream fish species.

Impact of seasonal hydrological variation on tropical fish assemblages: abrupt shift following an extreme flood event

AbstractPulsing hydrology is a major factor affecting fish communities in tropical river‐floodplain ecosystems. Species responses to flow alteration are however poorly understood and are thus difficult to predict. Here, we investigated temporal changes in fish community structure (taxonomic and functional) in the Tonle Sap Lake, a floodplain ecosystem in Cambodia that supports the world largest inland fisheries and a UNESCO biosphere reserve. Fish catches were monitored daily at five locations around the lake between 2012 and 2015, with 53 species obtained over the course of the field study. Nine fish traits were recorded and used to characterize the functional composition of fish communities. Temporal changes in functional community structure in response to hydrological variation were assessed using multiple co‐inertia analysis (MCOA) and cross‐correlation function (CCF) approaches. Analyses revealed an abrupt shift in functional structure following extreme flood events in 2013 that included a marked decrease in large‐bodied fish at high trophic levels. Also observed were seasonal changes in the relative abundance of life‐history strategies, feeding habits, and accessory respiratory adaptations. Black fish (species that are relatively sedentary with an equilibrium‐type life‐history strategy) dominated during low‐water periods, whereas white fish (migratory species with opportunistic or periodic life‐history strategies) were dominant during high‐water periods. Dynamics of local assemblage structure were fairly synchronous spatially and were independent of the distance between locations. Species responses to the peak flood pulse were estimated to lag 1–2 months. Findings from this study indicate that management of fisheries resources in the Tonle Sap Lake should consider differential responses of species to hydrology as a function of life‐history strategies and other functional traits as well as factors that may influence time lags in population and community changes to extreme flow events.

Marine protected areas do not prevent marine heatwave-induced fish community structure changes in a temperate transition zone

Acute climate events like marine heatwaves have the potential to temporarily or permanently alter community structure with effects on biodiversity and ecosystem services. We aimed to quantify the magnitude and consistency of climate driven community shifts inside and outside Marine Protected Areas before and after a marine heatwave using a kelp forest fish community dataset in southern California, USA. Abundance, biomass, diversity and recruitment of warm-water affinity species during the marine heatwave were significantly greater compared with prior years yet cool-water affinity species did not show commensurate declines. Fish communities inside MPAs were not buffered from these community shifts. This result is likely because the particular species most responsible for the community response to environmental drivers, were not fisheries targets. Resource managers working to preserve biodiversity in a changing climate will need to consider additional management tools and strategies in combination with protected areas to mitigate the effect of warming on marine communities.

Rapid change in Yangtze fisheries and its implications for global freshwater ecosystem management

AbstractFreshwater capture fisheries are globally essential for food security and aquatic biodiversity conservation. The Yangtze River Basin is the third longest and one of the most human‐influenced drainage basins worldwide. Since the founding of P. R. China in 1949, this large river system has suffered increasing human perturbation and its sustainable development is now severely challenged. Meta‐analysis showed that Yangtze River fisheries have experienced an extraordinary process of utilization–over‐exploitation–protection during the past 70 years, to an extent that other globally important rivers may never have encountered. Its fisheries appear to have collapsed over the past four decades, with yield decreasing to only 25% of an historical peak of 400,000 metric tonnes in the late 1950s. Endemic, migratory and rare fishes have been highly threatened with obvious changes in fish community structure and aquatic biodiversity. Anthropogenic activities, including impoundment of water in dams, discharge of pollutants and riverine modification for vessel navigation, have caused large decreases in fisheries yields. Projections from surplus production modelling showed potential for improvement under fishing ban scenarios, but without any prospect for full recovery to historical stock status. This study revealed that the change in fisheries resources was dominated by the social–ecological watershed system, and an integrated approach to river basin management is warranted. Better management of freshwater ecosystems to integrate food security with biodiversity conservation is urgently needed throughout the world, and the changes evident in the Yangtze River fish populations can serve as an informative global reference.

Temporal and spatial dynamics of fish community structure during watershed alteration in two Ouachita River systems

AbstractFish community composition is highly dynamic, but generally exhibits loose equilibrium within bounds of community structure in upland stream systems with minimal anthropogenic disturbance. Chronic anthropogenic disturbance can exceed ecological thresholds and shift fish community composition to an alternative state. Therefore, long‐term datasets are critical to understand spatiotemporal dynamics of fish community structure. We quantified temporal changes in fish communities in two Ouachita River systems during watershed alteration (i.e., development and reservoir construction) using a suite of multivariate and univariate analyses to assess changes in fish community structure and taxonomic and functional β‐diversity. We found fish community composition shifted in the Saline River basin possibly in response to human disturbance (e.g., development) and hydrologic variability. Furthermore, functional homogenisation occurred through time. In the Ouachita Headwaters basin, taxonomic homogenisation was evident and two fluvial specialists were not detected during the current period. Taxonomic and functional β‐diversity patterns were not consistent across basins demonstrating the complexity of biotic homogenisation. Our retrospective analyses showed human activities played a role in restructuring fish communities despite minimal invasion of exotic species. Ultimately, our study characterised fish community structure across snapshots of time and demonstrates the importance of increasing the frequency of sampling intervals and continuing long‐term collections with similar methods to enhance the understanding of community dynamics.

淡水鱼类功能生态学研究进展

PDF HTML阅读 XML下载 导出引用 引用提醒 淡水鱼类功能生态学研究进展 DOI: 10.5846/stxb201808141737 作者: 作者单位: 云南大学国际河流与生态安全研究院,云南大学国际河流与生态安全研究院,云南大学国际河流与生态安全研究院,云南大学国际河流与生态安全研究院,云南大学 作者简介: 通讯作者: 中图分类号: 基金项目: 国家重点研发计划项目（2016YFC0502103）；国家自然科学基金项目（41867072，41807402） Functional ecology of freshwater fish: research progress and prospects Author: Affiliation: Institute of International Rivers and Eco-security,Yunnan University,Kunming,Institute of International Rivers and Eco-security,Yunnan University,Kunming,Institute of International Rivers and Eco-security,Yunnan University,Kunming,Institute of International Rivers and Eco-security,Yunnan University,Kunming,Institute of International Rivers and Eco-security,Yunnan University,Kunming 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:在全球变化和人类活动的影响下，生物多样性正以前所未有的速度丧失，全球生物正经受第六次生物多样性危机。淡水生态系统是最脆弱的生态系统之一。淡水鱼类作为淡水生态系统的重要组成部分，承受着日趋严重的气候变化、栖息地退化、生物入侵和过度捕捞等压力，面临巨大的威胁。在此背景下，如何准确评估鱼类种群和群落对环境变化的响应，以及鱼类群落结构和功能的变化对生态系统功能的影响是淡水鱼类多样性和淡水生态系统保护的关键问题。近年来，淡水鱼类功能生态学的快速发展为解答这一问题提供了一个框架。系统地介绍了淡水鱼类功能生态学主要研究内容、方法、进展及其应用，并着重介绍了淡水鱼类功能特征及其与环境的关系、环境变化下的功能生态学响应研究。据此提出了淡水鱼类功能生态学未来的重点研究方向，指出了其在鱼类多样性保护和资源利用等领域的应用前景。 Abstract:Global biodiversity is currently experiencing the sixth major crisis and is declining at an unprecedented rate due to global change and anthropogenic activities. Furthermore, freshwater ecosystems are among the most vulnerable ecosystems, and freshwater fish, as the main biological components of such ecosystems, are increasingly threatened. Accurately assessing the responses of fish populations and communities to environmental changes (e.g., climate change, habitat degradation, biological invasion, and overfishing) and understanding the effect of changes in fish community structure and function on ecosystem functioning are essential to conserving freshwater fish and ecosystems. Recent studies of the functional ecology of freshwater fish have provided a framework for addressing these challenges. Here, we review the methodology, progress, and application of these studies, highlight the functional traits and responses of freshwater fish to environmental changes, discuss the application of new information to fish diversity conservation and fish resource utilization, and propose future research directions. 参考文献 相似文献 引证文献

Sequential fishways reconnect a coastal river reflecting restored migratory pathways for an entire fish community

River regulation infrastructure has been implicated in worldwide aquatic biodiversity loss. In‐stream barriers such as weirs prevent fish migration and the impact can be particularly severe for diadromous species. Fishways are frequently installed on in‐stream barriers to reconnect migratory pathways and rehabilitate diadromous fish populations. Sequential fishways may be necessary in rivers where multiple barriers prevent migration. We monitored a coastal fish community's response to fish passage restoration at 10 predominantly low‐level weirs in the freshwater reaches of the Nepean River in southeastern Australia. Few studies have simultaneously assessed fish community passage at successive fishways within a river system. Prior to the installation of the fishways, there was a gradient of reduced species diversity in an upstream direction including the absence of many diadromous species, despite the regular inundation frequency of most weirs. Following the installation of the fishways, species diversity was still greater in the downstream monitoring sites; however, there was evidence of a positive change in fish community structure in middle and upstream sites. Most notably, three diadromous species rapidly expanded their distribution upstream and one amphidromous species expanded its downstream distribution. This study demonstrates appropriately designed successive fishways can successfully reconnect river systems for an entire fish community, encompassing species with a broad range of swimming abilities and diverse life histories.

Reef-scale variability in fish and coral assemblages on the central Great Barrier Reef

Coral reefs are threatened by changing climatic conditions, which will potentially alter the frequency and severity of disturbances in coming decades, casting doubt over the potential for reefs to recover and re-assemble the structure of their fish and coral assemblages. Here, fish and coral assemblages were examined at four reefs similar in size, aspect, disturbance history and latitudinal position from 2006 to 2016. We quantified variation in species and functional level assemblage structure among reefs before and after disturbance and examined whether there was evidence of any recovery. Fish and benthic assemblages varied in density and diversity, but the proportion of fish functional groups was similar among reefs. While some post-disturbance recovery of the benthos was evident, changes in fish functional structure did not uniformly reflect benthic recovery patterns. The apparent disconnect between changes in fish community structure and coral recovery may be due to lagged responses of some fishes post-disturbance, lack of reliance on hard coral cover by some fish trophic groups, or retention of habitat complexity. These results highlight the importance of reef-scale data in determining capacity of coral reefs to recover from disturbance.

Fish assemblage change following the structural restoration of a degraded stream

AbstractDecades of anthropogenic pressure have harmed riverscapes throughout North America by degrading habitats and water quality and can result in the extirpation of sensitive aquatic taxa. Local stream restoration projects have increased in frequency, but monitoring is still infrequent. In 2010, Kickapoo Creek in East Central Illinois was subjected to a stream restoration project that included implementation of artificial riffles, riprap, scouring keys, and riparian vegetation. We monitored the restoration efforts for 6 years after the restoration through annual sampling efforts at restored and reference sites to determine changes in habitat and fish assemblage using standard habitat sampling and electrofishing techniques. We observed distinct temporal and spatial shifts in physico‐chemical parameters along with changes in fish community structure. Although biotic integrity remained moderately low in reference assemblages, restored reaches showed 3‐year delay in response to restoration, with biotic integrity positively linked to additional instream habitat and altered channel morphology. Larger substrate sizes, submerged terrestrial vegetation, and newly formed scour pools along with reduced siltation were found in the restored sites, in contrast to the reference sites. These changes resulted in increased species diversity, reduced number of opportunistic species and consequently an overall increase in health of fish communities. We also observed recruitment of habitat specialists and increase in species with reproductive strategies that rely on complex substrates. The results of this study highlight some of the complex dynamics driving reach‐scale restoration projects. We demonstrate the usefulness of structural restoration as a management tool to increase biotic integrity through long‐term alteration of critical habitat. The delay in the response of species to the restoration efforts emphasizes the need for long‐term continuous temporal and spatial monitoring.

Day–night change in fish community structure in a seagrass bed in subarctic waters

The day–night change in fish community structure over a year was examined in a seagrass bed in Lake Notoro, Hokkaido, northern Japan, to examine nocturnal increases in predation risk. This seagrass bed has previously been considered a predation refuge for juvenile and small-sized fishes. Species richness, abundance and biomass of piscivorous fishes during nighttime were higher than those during daytime on all sample dates surveyed (May, August and November 2013), indicating an increase in predation risk for juvenile and small-sized fishes during nighttime. The mean biomass-weighted trophic level of fish communities in the seagrass bed was also higher at night than in the day. The piscivorous fishes collected in the seagrass bed during the night included important fishery species. These may obtain energy through nocturnal feeding in the seagrass bed. Therefore, the function of seagrass beds as fish habitats should be re-evaluated by considering two possible characteristics contributing to fishery production: as a daytime predation refuge for juvenile and small-sized fishes, and as a nighttime foraging ground for piscivorous fishes.