Fish Community Dynamics Research Articles

Effects of Annual Droughts on Fish Communities in Mississippi Sound Estuaries

The Mississippi coastal region has two major rivers and four smaller rivers influencing the estuaries that make up the Mississippi Sound. The islands off Mississippi create a barrier which allows the area to be a widespread, productive estuarine region. With such a dependence on discharge from the drainages, it is important to understand the effect of salinity regimes on fish communities. Drought conditions in other regions have been shown to dramatically change the fish community structure. We used the long running Interjurisdictional Fisheries Program database (2006–2014) within Mississippi state waters and compared yearly fish communities between drought and non-drought years. Non-metric Multidimensional Scaling (nMDS), Analysis of Similarity (ANOSIM), and Indicator Species Analysis (ISA) were used to compare drought and non-drought conditions in the Mississippi Sound. During 2006 and 2007, which were identified as drought years by the Palmer Drought Severity Index (PDSI), differences in fish community structure were identified and compared to non-drought years (2008–2009 and 2011–2014). The ISA identified a total of eight species that were significantly influenced by drought years. Of the eight species, the abundance of seven species significantly decreased while the abundance of one species significantly increased. With an increasing human population in central and south Mississippi, pressure on freshwater resources is likely to increase, resulting in possible changes in the fish community dynamics of the Mississippi Sound. Understanding the influence of decreased river discharges will assist managers in determining the impacts of freshwater withdrawals during base flow periods.

Long-term assessment of ichthyoplankton in a large North American river system reveals changes in fish community dynamics

Larval fishes are sensitive to abiotic conditions and provide a direct measure of spawning success. The St. Clair – Detroit River System, a Laurentian Great Lakes connecting channel with a history of environmental degradation, has undergone improvements in habitat and water quality since the 1970s. We compared 2006–2015 ichthyoplankton community data with those collected prior to remediation efforts (1977–1978) to identify patterns in spatial and temporal variability. Both assemblages exhibited a predictable phenology, with taxa from the subfamily Coregoninae dominant in early spring followed by families Osmeridae, Percidae, and Moronidae (May–June) and Cyprinidae and Clupeidae (June–August). While higher densities of larval fish were found in the Detroit River, greater taxa richness and Shannon diversity were observed in the St. Clair River. System wide, 14 new taxa were observed in the 2000s study period. In addition, relative densities of two nonnative species, alewife (Alosa pseudoharengus) and rainbow smelt (Osmerus mordax), declined since the 1970s. Increased larval fish richness and decreased densities of nonnative taxa in the 2000s are consistent with improvements to environmental conditions.

Luis Alejandro Yáñez‐Arancibia 1944–2016

Luis Alejandro Yáñez‐Arancibia 1944–2016

Synthesizing stream fish community dynamics in the southern Great Plains and beyond

Synthesizing stream fish community dynamics in the southern Great Plains and beyond

The effect of coral restoration on Caribbean reef fish communities

The Caribbean has seen a dramatic loss of coral over the last 30 years due to direct and indirect anthropogenic factors, causing a decrease in reef three-dimensional complexity and fish abundance and diversity. Restoration practices, such as outplanting coral colonies onto degraded reefs, are increasingly used to revive reef ecosystems to preserve fisheries, tourism, and ecosystem functions, which are currently valued at $375 billion globally. However, few studies have examined whether coral restoration and the consequent addition of structural complexity can restore reef ecosystems. Thus, this study aims to better understand early fish community dynamics following restoration using Acropora cervicornis, a major reef building coral and focus species for restoration that has experienced a greater than 80% drop in cover since 1980. To examine fish dynamics after restoration, surveys of fish, environmental conditions, benthic seafloor characteristics, and rugosity were conducted on outplanted plots and control plots without outplants. Surveys were conducted off the north shore of St. Croix, USVI (17°46′15.0″N, 64°49′03.8″W) from May 30, 2016 to August 4, 2016, and on December 28, 2016, and January 4, 2017. Within a week of outplanting, fish abundance was significantly higher in experimental plots compared to controls. After outplanting, there was also an increase in fish species richness and a significant shift in fish community composition over time. These results demonstrate the early stages of fish colonization after outplanting A. cervicornis, providing insight into how restoration can cause rapid change in fish abundance, richness, and community composition.

The importance of time of day in structuring demersal ichthyofaunal assemblages on the West Florida Shelf

Although turnover of reef-fish assemblages based on time of day has been generally well documented, much less is known regarding diel dynamics of demersal fish communities along the continental shelf of the US Gulf of Mexico. We analyzed trawl data collected as part of the Gulf of Mexico Southeast Area Monitoring and Assessment Program (SEAMAP) to document diel changes in fish abundance and assess the relative importance of space and time of day in structuring demersal fish assemblages. Trawling operations were conducted day and night in neritic waters from southern Florida to eastern Alabama (West Florida Shelf). Ichthyofaunal assemblages differed by region and depth, but also by time of day (day, night, crepuscular) within region and depth categories. Both fish abundance and diversity were generally highest at night. Some day/night differences in abundance for particular species can be attributed to specific behaviors, such as nighttime foraging in open areas coupled with cryptic habits (e.g., burrowing, shelter-seeking). Prominent examples of such behavior-associated abundance patterns include cusk-eels (Ophidiidae), which are burrowers, and grunts (Haemulidae), which are closely associated with structural habitats during daytime. We document these strong diel trends in the SEAMAP trawl data and interpret them based on current understanding of the behavior of fish species and families and in relation to the development of ecosystem models for management purposes.

Influence of sampling frequency on detectability of fish community and fish species in a fishery-independent survey

Understanding the dynamics and regulation of a particular ecological process requires monitoring of the process at appropriate spatial and temporal scales. Information collected at an inappropriate spatio-temporal scale may be insufficient for capturing spatio-temporal dynamics of fish populations and community. In this study, a Monte Carlo method was developed to evaluate the detectability performances of different sampling frequencies, sampling timings and sampling intensities on fish community indices and fish species. Species richness indices tended to decrease with an increased sampling frequency, while species diversity indices had small changes in response to changes in sampling frequency. The diversity index was more likely to be influenced by the choice of sampling timing compared to the richness index. The total number of species, especially seasonal and rare species present in the simulated sampling, increased with sampling frequency. Although sampling frequency is more important than sampling intensity, sampling intensity is also important for the detectability of fish species. This study showed that sampling frequency and intensity could greatly influence the estimation of fish community. Choices of sampling timing, sampling frequency and intensity may result in different estimates of fish species compositions and community structure. It is very necessary to consider the importance of sufficient sampling frequency and intensity in a survey program.

Fish community dynamics in an inland floodplain system of the Okavango Delta, Botswana

Tropical floodplain fish populations fluctuate at temporal scales and understanding the variability in these systems will contribute to comprehensive management of these resources. Therefore, the aim of this study was to assess the dynamics of a floodplain fish assemblage. Data were collected using standard methods between 1999 and 2009 from the delta's panhandle. Various analytical tools (e.g. CCA, SIMPER, ANOVA, etc.) were used to assess fish assemblage dynamics at seasonal and annual scales. ANOVA and cluster analyses showed that the fish assemblage underwent significant changes along the seasonal hydrograph, while index of relative aboundance (%IRI) revealed that the fish assemblage was dominated by Clarias gariepinus, Schilbe intermedius and Hydrocynus vittatus respectively. These species, including Clarias ngamensis and Marcusenius altisambesi, contributed more than 50% to variations in fish assemblage structure along the seasonal hydrograph (based on SIMPER analysis). Furthermore, canonical correspondence analysis (CCA) revealed a significant (p=0.004) association between environmental factors and fish assemblage structure. CCA analysis also showed that spawning for different species is associated with various environmental factors. Annually, results showed that C. gariepinus dominated the fish assemblage during low flood years, while S. intermedius dominated during high flood years. Detrended correspondence analysis (DCA) showed that the hydrological gradient had a significant effect on fish assemblage structure at an annual scale, while SIMPER analysis established significant variations in fish assemblage structure among years characterized by different hydrological features. One major conclusion we made was that fish assemblages are stochastically different at an annual scale. This study contributes knowledge to floodplain fish ecology and thus enhances fisheries management.

Spatial and temporal dynamics of nearshore fish communities in Lake Michigan and Lake Huron

Abstract Ecosystem changes across the Great Lakes have increased the importance of understanding the role of nearshore zones (

Assessing the potential of remote sensing-derived water quality data to explain variations in fish assemblages and to support fish status assessments in large lakes

Remote sensing techniques may provide a higher temporal and spatial resolution than traditional water monitoring methods. We tested if this auxiliary information can be used to (i) explain patterns in fish assemblage composition and (ii) test candidate metrics to assess ecological status in large lake water bodies. We used MERIS-derived layers describing chlorophyll a, total suspended matter, and colored dissolved organic matter (CDOM) overlaid on all available fish monitoring data from the four largest Swedish lakes (Vanern, Vattern, Malaren, and Hjalmaren). We assessed the influence of remote sensing-derived parameters in the pelagic, offshore benthic, and the inshore benthic habitats. Our results demonstrated that chlorophyll a and CDOM together with depth at the sampling site explained a significant part of the variation in the distribution of fish assemblages. These predictors were particularly important not only in pelagic, but also in inshore benthic areas. Furthermore, we identified three potential candidate metrics to assess pressure from eutrophication in large lakes: density of pelagic fishes, biomass of planktivorous species, and the proportion of cyprinids when roach was excluded. Remote sensing was considered a useful tool to support analyses of fish community composition and dynamics.

Acoustic measures of lake community size spectra

Acoustic methods were tested as an alternative to catch data to measure size spectra of freshwater fish communities in Lac du Bonnet (LdB), Manitoba, Canada. Eleven daytime hydroacoustic surveys conducted in 2011 and 2012 enabled length-frequency spectra of fish communities to be calculated within LdB. Fish echoes tracked and converted to length (>5 cm) formed size spectra with significant linear regressions in all cases (p values < 0.05, R2 values from 0.87 to 0.99). Fish abundance (spectral height) was greater in 2011 (mean ± SD = 0.19 ± 0.15) than in 2012 (–0.19 ± 0.20), decreasing through the summer sampling season. Both abundance and size composition (spectral slope) of fish communities differed between three basins of varying bathymetry, with steepest slopes and lowest heights associated with the shallowest waters. We conclude that acoustically derived size spectra provide an efficient means to detect and monitor fish community dynamics over varied spatial and temporal scales in aquatic ecosystems where fish are not highly aggregated and hence single acoustic targets predominate.

Dynamics of an upland stream fish community over 40 years: trajectories and support for the loose equilibrium concept

Previous theoretical models and empirical studies suggested that communities can exist in a "stochastic" or "loose" equilibrium, diverging transiently but eventually returning toward earlier or average structure, in what we call here the "loose equilibrium concept" (LEC). We sampled the fish communities at 12 local stream reaches spaced broadly throughout a relatively undisturbed watershed in the Ozark Mountains of northern Arkansas, USA, in 11 surveys from 1972 to 2012 at a scale of decades, and at a subset of five of these local sites in a total of 16 surveys, allowing tests of the LEC at different spatial and temporal scales. Multivariate analyses of the dynamics of communities over the 40-year period provided support for the LEC at both "global" and "local" scales within the watershed. At the broadest spatial scale, core species numerically dominated the community, and most common species remained so across all decades. In spite of two extraordinary floods, and interannual variation in abundance of some species, the 12-site and five-site global communities and eight of 12 local communities repeatedly returned toward average positions in multivariate space. Trajectories of the global and local fish communities varied relative to model hypothetical trajectories that were based on gradual vs. saltatory changes, and prevalence of returns toward average community structure. Beta diversity among sites was variable across time, but beta partitioning consistently showed that pure spatial turnover dominated over nestedness, because many common species were consistently distributed either upstream or downstream. This study suggests that vertebrate communities in relatively undisturbed environments may display dynamics consistent with the LEC. The LEC, combined with quantification of community trajectory patterns, can help to clarify whether systems are moving about within ranges of conditions that reflect expected noise, or, conversely, have moved so far out of previous bounds, as a result of climate change or human intervention, that they are permanently changed or "novel."

Diel Feeding Ecology of Slimy Sculpin in a Tributary to Skaneateles Lake, New York

Abstract Interactions among the benthic community are typically overlooked but play an important role in fish community dynamics. We examined the diel feeding ecology of Slimy Sculpin (Cottus cognatus) from Grout Brook, a tributary to Skaneateles Lake. Of the six time periods examined, Slimy Sculpin consumed the least during the nighttime (2400 h and 0400 h). Chironomids were the major prey consumed during all time periods except for 2400 h when ephemeropterans were the major prey consumed. There was a moderate preference by Slimy Sculpin for food from the benthos (0.59 ± 0.06) with Diptera (Chironomids), Ephemeroptera (Baetidae), and Trichoptera (Brachycentridae) representing the major taxa. Slimy Sculpin appear to be opportunistic feeders selecting what is most available in the brook. Index of fullness was variable and averaged 1.15% across the diel cycle. Daily ration was measured as a function of fish dry body weight and ranged from 0.12 to 0.22. Estimates of daily consumption ranged from 0.007% to 4....

Misapplied survey data and model uncertainty result in incorrect conclusions about the role of predation on alewife population dynamics in Lake Huron: a comment on

Drastic recent and ongoing changes to fish populations and food webs in the Great Lakes have been well-described (Riley et al. 2008; Barbiero et al. 2009; Nalepa et al. 2009; Fahnenstiel et al. 2010; Evans et al. 2011; Gobin et al. 2015), and uncertainty regarding their potential effects on fisheries has caused concern among scientists and fishery managers (e.g., Dettmers et al. 2012). In particular, the relative importance of “bottom-up” (e.g., lower trophic level changes) versus “top-down” (e.g., predation) factors to fish community changes in the Great Lakes have been widely debated (e.g., Barbiero et al. 2011; Eshenroder and Lantry 2012; Bunnell et al. 2014). In Lake Huron, recent ecosystem changes have been particularly profound, and populations of alewife (Alosa pseudoharengus), an offshore pelagic prey fish, collapsed in 2003 and have yet to recover (Riley et al. 2008, 2014). He et al. (2015) recently used a series of linked ecologicalmodels to assess the role of predation in the dynamics of the offshore prey fish community in Lake Huron. While we believe that they provide a novel method for combining bioenergetics and stock assessment modeling, we question the validity of their conclusions because of the misapplication of survey data and the lack of critical interpretation of theirmodeling efforts. Here we describe howHe et al. (2015) have misapplied bottom trawl data from Lake Huron, and we provide examples of how this has resulted in erroneous conclusions regarding the importance of predation to the population dynamics and collapse of alewife in Lake Huron.

Dietary Habits and Distribution of Some Fish Species in the Pansipit River-Lake Taal Connection, Luzon Island, Philippines

The interface between lakes and their outlet rivers is an interesting research site for fish community dynamics because it is immediately exposed to disturbances in lake ecosystems. In this paper, observations on the species composition, dietary habits and distribution of fish in the upstream area of Pansipit River - sole outlet of Lake Taal, were presented. Fish samples comprised of juvenile fish from 12 species, including four that were introduced. These non-native species were more abundant than native fish caught. Dietary analyses suggest that non-native fish have a wider dietary breadth compared to native fish and may be one reason why introduced fish populations have exceeded native fish populations in the area. Fish activity varied depending on time of day in certain sub-sites and these fishes aggregated in intermittent deep pools when water depth is uniformly low in the river during the dry season. These suggest that fish abundance in the area is associated with river water depth and other environmental factors. Overall, the study stresses the need for more in-depth research in Pansipit River given its importance as a migratory path and its potential as a refugia for the riverine fish community.

Fish community in a large coastal subtropical lake: how an environmental gradient may affect the structure of trophic guilds

Biological communities change in time and space under driving pressures from differences in habitat structure, resource availability, interspecific competition, predation and other factors. Spatial heterogeneity, or patchiness, has been recognized as an important feature in a number of lake systems. In this study, we analysed changes in the seasonal dynamics of fish community in a subtropical lake over one year, focusing on the spatial and temporal distribution of fish biomass and species composition. Mangueira is a large shallow lake (3 m deep in average, 90 km long, 3-10 km wide, ≈ 820 km2) located along the Atlantic coast-line in southern Brazil (33◦3122S 53◦0748W). Mangueira Lake presents longitudinal gradients in both biotic and abiotic factors, and a principal components analysis (PCA) showed temporal and spatial gradients in the system. Analysis of similarity (ANOSIM) showed significant differences between the north and south extremes of Mangueira Lake. Secchi transparency (p < 0.001), dissolved organic carbon (DOC) (p = 0.03) and chlorophyll a (p < 0.001) were identified as the driving factors for this spatial gradient. A two-way ANOVA was adjusted for each data set. Chlorophyll a (p = 0.017), fish captures (p = 0.033) and fish richness (p = 0.026) were different according to the sampling site (after removing the seasonal effect), while only fish richness presented significant seasonal variation after removing the sampling site effect (p = 0.041). This longitudinal gradient can be related to two main driving pressures. The first is prevailing winds from northeast to southwest, with predictable consequences for the whole trophic cascade. The other structuring pressure is the interface of the Taim wetland with northern Mangueira Lake. Thus, the northern part presents more turbid water, muddy sediments and increased chlorophyll a concentration, while the southern part is characterized by increased water transparency, less chlorophyll a concentration and more PVI (percent volume infested) of submerged macrophytes, demonstrating the spatial heterogeneity of the ecosystem.

An evaluation of implementing long-term MSY in ecosystem-based fisheries management: Incorporating trophic interaction, bycatch and uncertainty

Maximum sustainable yield (MSY), often defined in relation to a single species considered in isolation, has long been considered a cornerstone in fisheries management. It is difficult to expand the concept of MSY for the purpose of ecosystem-based fisheries management (EBFM). Here we consider MSY for a fishery in a multispecies fish community by addressing issues of trophic interaction and bycatch, along with parameter uncertainty. A size-spectrum model, which fully considers trophic interactions within the fish community, was used for simulating various fisheries scenarios including a single species fishery, a multispecies stow-net fishery, and a multispecies trawl fishery. Population biomasses, yields, and ecological indicators were used to assess the dynamics of the fishery and fish community status. The single species fishery with no bycatch resulted in a low impact on non-target stocks, but led to the collapse of the target stock at low fishing mortality rates. The stow-net and trawl fisheries had broader ecosystem impacts, but allowed target stocks to be fished at much higher fishing mortality rates with higher yields. Ecological indicators were related non-linearly to fishing mortality, possibly diminishing their effectiveness as management tools. Background resource carrying capacity was found to be a greater source of uncertainty than reproductive efficiency. This study demonstrates that bycatch mortality can play an important role in trophic interactions likely via predation release and depensation, and thus influence the resilience of fisheries to fishing pressure. The study indicates that the combination of mixed fisheries and multispecies effects lead to complex fish community dynamics that may present additional challenges for fisheries management.

Dynamics of an upland stream fish community over forty years: trajectories and support for the loose equilibrium concept

Dynamics of an upland stream fish community over forty years: trajectories and support for the loose equilibrium concept

Erratum to: Temporal dynamics of fluvial fish community caused by marine amphidromous species in the Shubuto River, southwestern Hokkaido, Japan

We investigated the fluvial fish communities at 16 sites that cover the entire Shubuto River in northern Japan in July and September 2010. A total of 5,552.9 g of biomass and 980 individuals were identified as produced by and belonging to 11 species, and 7,079.7 g of biomass and 2,587 individuals were pinpointed as produced by and belonging to 17 species. The data on the 11 and 17 species were recorded in July and September 2010, respectively. The July and September data exhibited significant differences in individual and biomass compositions (G-test; both P < 0.001). The number of recorded amphidromous Gymnogobius opperiens and Rhinogobius sp. (a species complex of Rhinogobius brunneus) individuals was significantly affected by the interaction term between watercourse distance from the sea and sampling season (July or September). By contrast, no such significant influence was found for the biomass produced by the aforementioned species. Fisher’s exact tests revealed that the G. opperiens and Rhinogobius sp. compositions during the growth stage (larva–juvenile vs. post-juvenile) significantly differed between July and September 2010. These results are probably attributed to part of the seasonal trend exhibited by the fish communities in the Shubuto River; that is, the spatial pattern of the fluvial fish communities from July to September is probably caused by an increase in the species occurrence and larval and juvenile recruitment of G. opperiens and Rhinogobius sp. migrating from the sea to the river.

Fish Community Distributions and Movements in Two Tributaries of the San Juan River, USA

AbstractRecognizing how stream fish communities—and their habitats—differ across space and time relative to their position in stream networks (i.e., main‐stem versus tributary habitats) is increasingly important for the conservation of imperiled native fish communities in altered river networks such as those in the Colorado River basin. We studied the patterns (community composition) and processes (movements) that shape species occurrences and distributions in two tributaries of the San Juan River, Utah and New Mexico, between 2012 and 2014. Our results show that distance from the San Juan River was a strong driver of tributary fish community structure, whether through declines in species richness (Chaco Wash) or species turnover (McElmo Creek), and that these patterns coincided with habitat gradients (i.e., depth, substrate, and width). Occurrences of passive integrated transponder (PIT)–tagged fish at a stationary antenna in McElmo Creek just upstream of its confluence with the San Juan River varied by species but generally were associated with spring spawning migrations (Flannelmouth Sucker Catostomus latipinnis, Razorback Sucker Xyrauchen texanus), exploratory movements (Colorado Pikeminnow Ptychocheilus lucius), and monsoon flooding (Channel Catfish Ictalurus punctatus, Razorback Sucker). Occurrences of PIT‐tagged fish in Chaco Wash were dominated by endangered Razorback Suckers and Colorado Pikeminnows, suggesting that this habitat supplies useful habitat, forage, or both. Given the common occurrences of native fishes in these tributaries, incorporating these habitats into basinwide management actions seems necessary to fully understand the spatiotemporal dynamics of native and nonnative fish communities.