Among- and within-tributary responses of riverine fish assemblages to habitat featuresContribution of the Group for Interuniversity Research in Limnology (GRIL). We dedicate this paper to the memory of our colleague Réjean Fortin.

2008 ◽  
Vol 65 (7) ◽  
pp. 1379-1393 ◽  
Author(s):  
Yorick Reyjol ◽  
Marco A. Rodríguez ◽  
Nathalie Dubuc ◽  
Pierre Magnan ◽  
Réjean Fortin
Keyword(s):  
Environmental Variables ◽  
Fish Assemblages ◽  
Environmental Gradients ◽  
Assemblage Structure ◽  
Foraging Efficiency ◽  
Habitat Features ◽  
Ottawa River ◽  
Mixed Regression ◽  
Riverine Fish ◽  
Predictable Variation

We quantified fish abundance and environmental variables at 170 sites distributed among 11 tributaries of the Ottawa River, Quebec, Canada, to assess the relative importance of among- and within-tributary variation in riverine fish assemblages. Additionally, we determined (i) which environmental variables were most strongly associated with each type of variation and (ii) whether ecomorphological traits in fish assemblages were predictably related to environmental gradients. Partitioning of variation by means of partial ordination indicated that assemblages were less variable among (38.7% of the total variation) than within (61.3%) tributaries. Water transparency singly accounted for 33.3% of the variation among tributaries, whereas macrophyte cover and river width jointly accounted for 8.3% of the variation within tributaries. These results suggests that differences in habitat features among tributaries may account for a substantial fraction of the predictable variation in assemblage structure at the watershed scale, an aspect not emphasized in previous studies of riverine fish assemblages. Mixed regression analyses relating ecomorphological traits to environmental variables showed that the environmental variables most strongly associated with assemblage structure were significantly related to traits associated with predator avoidance or foraging efficiency.

Demersal Fish Assemblages on the Scotian Shelf, Northwest Atlantic: Spatial Distribution and Persistence

1989 ◽  
Vol 46 (S1) ◽  
pp. s134-s152 ◽  
Author(s):  
Robin Mahon ◽  
Robert W. Smith
Keyword(s):  
Environmental Variables ◽  
Fishery Management ◽  
Fish Assemblages ◽  
Environmental Gradients ◽  
Demersal Fish ◽  
Assemblage Structure ◽  
Bay Of Fundy ◽  
Scotian Shelf ◽  
Species Groups ◽  
Temporal And Spatial

This study is based on 18 surveys, 12 in summer, and three each in spring and fall, with bottom trawls over the Scotian Shelf and Bay of Fundy. The data analysis sequence was: temporal and spatial aggregation of trawl sets; estimation of interspecies and intersite distance indices; clustering and ordination of sites and species, and discrimination of site groups using environmental variables. Nine species-groups, and 10 site-groups were defined, and displayed in a two-way table. Depth and temperature were the environmental variables most strongly associated with differences in assemblage structure among site-groups. Changes in assemblage structure from one area to another were distinct but apparently gradual, with no sharp assemblage boundaries. This pattern is expected if species are distributed independently on environmental gradients, rather than if assemblages consist of highly co-evolved, interdependent species. The observed spatial patterns were highly persistent through time. There are regions which are relatively homogeneous with regard to species composition and which can therefore be useful in dealing with bycatch problems. However, this study does not indicate the existence of discrete assemblages which might be appropriate as ecologically based fishery management units.

scholarly journals Effects of natural and anthropogenic environmental changes on riverine fish assemblages: a framework for ecological assessment of rivers

2005 ◽  
Vol 48 (1) ◽  
pp. 91-108 ◽  
Author(s):  
Francisco Leonardo Tejerina-Garro ◽  
Mabel Maldonado ◽  
Carla Ibañez ◽  
Didier Pont ◽  
Nicolas Roset ◽  
...  
Keyword(s):  
Environmental Changes ◽  
Fish Assemblages ◽  
Environmental Gradients ◽  
Geographic Area ◽  
Ecological Assessment ◽  
Natural Conditions ◽  
Detailed Understanding ◽  
Assemblage Composition ◽  
Ecological Regions ◽  
Riverine Fish

Freshwater is a basic need for the mankind. Effective biological tools (ecologically based, efficient, rapid and consistently applicable to different ecological regions) are needed to measure the "health" of rivers. Adapting such tools over a broad geographic area requires a detailed understanding of both the patterns of organisms assemblage composition and distribution within and among water bodies under natural conditions, and the nature of the major environmental gradients that cause or explain these patterns. A comprehensive review of the available litterature dealing with the identification of environmental factors structuring riverine fish assemblages under natural conditions permits to identify the most consistent ones.

scholarly journals Correlations Between Fish Assemblage Structure and Environmental Variables of Taruwa Pond in Nawalparasi District, Province No. 4, Nepal

2021 ◽  
Vol 11 (1) ◽  
pp. 1-8
Author(s):  
JASH HANG LIMBU ◽  
KESHI CHAUDHARY
Keyword(s):  
Temporal Variation ◽  
Fish Assemblage ◽  
Environmental Variables ◽  
Fish Assemblages ◽  
Mesh Size ◽  
Assemblage Structure ◽  
Fish Assemblage Structure ◽  
Fish Community Structure ◽  
Water Parameters ◽  
Analysis Of Similarity

The correlations between fisheries diversity and environmental variables of Nepal’s Pond are poorly understood. This study aims to investigate temporal variation of fish assemblage at Taruwa Pond in Nawalparasi district, Province no. 4, Nepal from October 2018 to April 2019. For the fish agglomeration, cast net of 4 kg in weight and 3.80 m in length and 22.5 m breadth with 12 mm mesh size was used. In total, 579 individuals representing 16 fish species, 10 families, and 12 genera were recorded. According to similarity percentage analysis, the most contributory species were Puntius ticto (27.92%) followed by Danio devario (12.06%), Puntius terio (9.76%), Badis badis (7.31%), Lepidocephalichthys guntea (5.57%) and Puntius sophore (5.57%). Analysis of similarity suggested that fish community structure was significantly different in temporal variation (R = 0.321, p<0.01). Based on the cluster analysis, fish assemblages were isolated into two distinct groups at Bray-curtis similarity. The Canonical Correspondence Analysis distinctly indicated that the water parameters of dissolved oxygen, carbon-dioxide, depth, and water temperature play an important role in influencing the fish assemblage structure of Taruwa Pond.

scholarly journals Environmental heterogeneity explains species turnover but not nestedness in fish assemblages of a Neotropical basin

2017 ◽  
Vol 29 (0) ◽  
Author(s):  
Oscar Eduardo Peláez ◽  
Filipe Manoel Azevedo ◽  
Carla Simone Pavanelli
Keyword(s):  
Species Composition ◽  
Beta Diversity ◽  
Environmental Variables ◽  
Environmental Heterogeneity ◽  
Fish Assemblages ◽  
Environmental Gradients ◽  
Species Turnover ◽  
Paraná River ◽  
Fish Diversity ◽  
Parana River

Abstract Aim: Heterogenous environments can contribute to maintain biodiversity. Traditionally beta diversity studies have focused on determining the effect of environmental variables on the total dissimilarity of species composition. However, decomposing beta diversity in species replacement and nestedness could give new insights on mechanisms affecting spatial patterns of biodiversity. We aimed to answer two main questions about spatial patterns of fish diversity in a Neotropical basin: 1) whether some regions contribute differently to fish diversity, and 2) whether species turnover and nestedness are explained by environmental gradients. Methods Sampling sites in the main channel and tributaries of the Upper Paraná River were sampled between 2013 and 2015. We partitioned beta diversity and tested the relationship of turnover and nestedness with environmental variables. Results 74 species were captured. Some of these species were restricted to different sites, contributing to variation in species composition. Hill numbers showed a trend for higher diversity in the tributaries than in Paraná River sampling sites, and the partition of beta diversity revealed that species replacement drove dissimilarity in species composition. Only total beta diversity and turnover were related to environmental variables, mainly conductivity and turbidity. Conclusions Species diversity and composition of fish assemblages in the Upper Paraná River could be related to environmental gradients. Overall, our results suggest that Paraná River tributaries contribute to increase environmental heterogeneity, and hence to maintain a high diversity and variation in species composition. For that reason, we strongly recommend preserving highly heterogeneous habitats in the region.

scholarly journals Environmental Variation and How its Spatial Structure Influences the Cross-Shelf Distribution of High-Latitude Coral Communities in South Africa

Diversity ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 57 ◽  
Author(s):  
Sean N. Porter ◽  
Michael H. Schleyer
Keyword(s):  
South Africa ◽  
Continental Shelf ◽  
High Latitude ◽  
Environmental Variables ◽  
Environmental Gradients ◽  
High Tide ◽  
Environmental Variation ◽  
Shelf Edge ◽  
Spatial Differences ◽  
Coral Communities

Coral communities display spatial patterns. These patterns can manifest along a coastline as well as across the continental shelf due to ecological interactions and environmental gradients. Several abiotic surrogates for environmental variables are hypothesised to structure high-latitude coral communities in South Africa along and across its narrow shelf and were investigated using a correlative approach that considered spatial autocorrelation. Surveys of sessile communities were conducted on 17 reefs and related to depth, distance to high tide, distance to the continental shelf edge and to submarine canyons. All four environmental variables were found to correlate significantly with community composition, even after the effects of space were removed. The environmental variables accounted for 13% of the variation in communities; 77% of this variation was spatially structured. Spatially structured environmental variation unrelated to the environmental variables accounted for 39% of the community variation. The Northern Reef Complex appears to be less affected by oceanic factors and may undergo less temperature variability than the Central and Southern Complexes; the first is mentioned because it had the lowest canyon effect and was furthest from the continental shelf, whilst the latter complexes had the highest canyon effects and were closest to the shelf edge. These characteristics may be responsible for the spatial differences in the coral communities.

Relationships between riverine fish and woody debris: implications for lowland rivers

1999 ◽  
Author(s):  
D. A. Crook ◽  
A. I. Robertson
Keyword(s):  
Woody Debris ◽  
Fish Habitat ◽  
Reference Points ◽  
Positive Development ◽  
Lowland River ◽  
Predator Prey ◽  
Lowland Rivers ◽  
Habitat Features ◽  
Surface Areas ◽  
Riverine Fish

This paper reviews studies of relationships between riverine fish and woody debris at micro- and meso-habitat scales, and discusses the potential functions of instream structure for lowland river fish. Experimental research, mainly in North America, has identified three main functions of woody debris as microhabitat for fish in upland streams: overhead cover that decreases predation risk both vertically and horizontally; horizontal visual isolation that reduces contact between fish; and velocity refuge which minimizes energetic costs. As with habitat features in other aquatic environments, increasing spatial complexity of woody debris may modify predator–prey interactions and provide greater surface areas for the growth of prey items. Woody debris may also provide spatial reference points for riverine fish to assist them in orienting within their surroundings. Lowland rivers differ from upland streams in terms of a number of physical variables, including turbidity, depth and water turbulence. Relationships between fish and woody debris in lowland rivers are likely to rely on mechanisms different to those in upland streams. Recent initiatives involving the reintroduction of woody debris into previously cleared lowland rivers to replace lost fish habitat are a positive development for lowland river restoration. However, if woody debris reintroduction is to maximally benefit lowland river fisheries, there is a requirement for better understanding of the ecological functions of woody debris in lowland rivers.

scholarly journals Interannual variability of larval fish assemblages associated with water masses in winter in the Taiwan Strait during 2007–2013

2021 ◽  
Author(s):  
Yu-Kai Chen ◽  
Chia-Yi Pan ◽  
Yi-Chen Wang ◽  
Hsiu-Ju Tseng ◽  
Bo-Kun Su ◽  
...  
Keyword(s):  
Fish Assemblages ◽  
Larval Fish ◽  
Taiwan Strait ◽  
Assemblage Structure ◽  
Sea Surface ◽  
Coastal Current ◽  
Annual Variations ◽  
Frontal Zones ◽  
The Taiwan Strait

AbstractIn this study, the interannual variations of ichthyoplankton assemblages in the Taiwan Strait (TS) during the winters of 2007–2013 were determined. The cold China Coastal Current (CCC) and Mixed China Coastal Water (MCCW) intruded into the TS and impinged with the warm Kuroshio Branch Current (KBC) with annual variations. Consequently, the ichthyoplankton community in the TS was mainly structured into two assemblages characterized by differing environmental conditions. The composition of the warm KBC assemblage was relatively stable and was characterized by Diaphus B and Bregmaceros spp. By contrast, the cold MCCW assemblage demonstrated considerable variations over the years, with demersal Gobiidae and Scorpaenidae families considered the most representative. In addition, Benthosema pterotum and Trichiurus spp. were common in both KBC and MCCW assemblages. The distribution of the KBC assemblage demonstrated sharp boundaries in the frontal zones, whereas changes in the assemblage structure between the frontal zones were gradual for the MCCW assemblage, particularly when demersal taxa were dominant. Sea surface temperature and salinity were most strongly associated with variability in the assemblage structure during the study period. Thus, this paper provides a better understanding of long-term larval fish dynamics during winter in the TS.

scholarly journals Seasonal flooding, instream habitat structure and fish assemblages in the Mulgrave River, north-east Queensland: towards a new conceptual framework for understanding fish-habitat dynamics in small tropical rivers

2008 ◽  
Vol 59 (2) ◽  
pp. 97 ◽  
Author(s):  
Thomas S. Rayner ◽  
Bradley J. Pusey ◽  
Richard G. Pearson
Keyword(s):  
Habitat Structure ◽  
Fish Assemblages ◽  
Fish Habitat ◽  
Dry Season ◽  
Assemblage Structure ◽  
Tropical Rivers ◽  
Wet Season ◽  
Seasonal Flooding ◽  
North East ◽  
Habitat Dynamics

Strong relationships between seasonal flooding, instream habitat structure and fish assemblages have been well documented in large tropical rivers (e.g. the flood pulse concept). However, the mechanics of these relationships are likely to differ substantially in smaller coastal rivers, such as those in Costa Rica, south-east Brazil and Australia’s Wet Tropics. These systems typically feature steep upland streams with short, deeply incised lowland channels and poorly connected floodplains. This hypothesis was investigated by documenting spatial and temporal variation in fish-habitat relationships in the Mulgrave River, north-east Queensland. Sampling was conducted at four lowland sites under a range of flow conditions, from dry-season baseflows to a one-in-ten-year flood. Longitudinal environmental gradients and fine-scale habitat patches were important in regulating fish assemblage structure during the dry season. However, high wet-season flows, constrained by the deep channel, acted as disturbances rather than gentle flood-pulses. In particular, the mobilisation of bed sediments led to scouring of aquatic vegetation and a dramatic reduction in habitat heterogeneity. Seasonal movements of fish led to significant changes in assemblage structure – from a community dominated by Neosilurus ater, Hypseleotris compressa, Awaous acritosus and Redigobius bikolanus during the dry season, to one dominated by Nematalosa erebi, Ambassis agrammus and Glossamia aprion during the wet season. Based on these observations, together with information from the literature, a conceptual model of fish-habitat dynamics is presented that is better suited to small tropical rivers than those developed in larger systems with expansive floodplains.

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