scholarly journals Contribution of environmental and spatial factors to the structure of stream fish assemblages at different spatial scales

2013 ◽  
Vol 23 (2) ◽  
pp. 208-223 ◽  
Author(s):  
Hikaru Nakagawa
2008 ◽  
Vol 65 (2) ◽  
pp. 245-257 ◽  
Author(s):  
Henry F Wilson ◽  
Marguerite A Xenopoulos

We examined the relationship between multiple spatial scales of fish assemblage structure and land cover in streams of a northern Great Plains ecoregion. We used regional richness measurements, an index of biotic integrity (IBI), and nonmetric multidimensional scaling (NMS) ordination to characterize fish assemblages. These metrics were related to regional catchment landscape at two spatial scales (overall catchment, overall riparian) and then to a set of local subcatchments from within these catchments at three scales (overall subcatchment, overall riparian buffer, and reach). Relationships between catchment fish richness, IBI scores, and landscape predictors were strongest at the riparian scale, with the strongest single predictor being riparian forest (r2 = 0.63, P < 0.01). NMS ordination analysis showed clear similarities between fish species assemblages in agriculturally dominated catchments and assemblages found in smaller headwater streams. At the same time, forested catchments and catchments with larger areas exhibited similar fish species assemblages. Our results indicate that both local and regional stream fish assemblages are structured by broader-scale landscape characteristics, with land cover providing a better indication of overall available habitat volume than catchment area or stream order.


2003 ◽  
Vol 60 (5) ◽  
pp. 491-505 ◽  
Author(s):  
Lizhu Wang ◽  
John Lyons ◽  
Paul Rasmussen ◽  
Paul Seelbach ◽  
Thomas Simon ◽  
...  

We analyzed data from 79 watersheds in an undegraded U.S. ecoregion to identify key environmental factors that explained stream fish assemblage patterns and to evaluate the relative influence of environmental factors operating at different spatial scales. A few key factors from the watershed, reach, and riparian scale explained a significant amount of the variance in fish attributes. Three environment–fish associations were evident. Top carnivores and intolerant cold-water fishes were associated with relatively narrow, deep, high-gradient, cold streams with strong groundwater inputs. Tolerant cyprinids occurred in small streams with low groundwater input, low dissolved oxygen, and abundant macrophytes. A diverse assemblage (Cyprinidae, Catostomidae, Centrarchidae, Percidae) existed in warm, wide streams in watersheds dominated by lacustrine sand and gravel geology and abundant wetlands and lakes. Overall, reach-scale variables directly explained the most, watershed-scale variables less, and riparian-scale variables the least variation in fish attributes. Watershed and riparian variables had indirect connections with fishes through their direct influence on reach variables. In conjunction with findings from more degraded regions, we conclude that the relative influence of reach-scale variables on fishes are greatest in undegraded areas and that direct effects of watershed-scale variables are increasingly important as human modifications of the landscape increase.


2018 ◽  
Vol 28 (2) ◽  
pp. 317-329 ◽  
Author(s):  
Luciano F. A. Montag ◽  
Kirk O. Winemiller ◽  
Friedrich W. Keppeler ◽  
Híngara Leão ◽  
Naraiana L. Benone ◽  
...  

2011 ◽  
Vol 92 (4) ◽  
pp. 447-460 ◽  
Author(s):  
Yuichi Kano ◽  
Kaori Ohnishi ◽  
Yasuo Tomida ◽  
Naoyo Ikeda ◽  
Naomi Iwawaki ◽  
...  

2012 ◽  
Vol 31 (3) ◽  
pp. 882-894 ◽  
Author(s):  
Jacob F. Schaefer ◽  
Scott R. Clark ◽  
Melvin L. Warren

<i>Abstract.</i>—Anthropogenic activities including urbanization, agriculture, and dams degrade stream habitats and are a dominant reason for global biodiversity declines in fluvial fish assemblages. Declining diversity trends have been well documented in many regions of the world; however, fishes vary regionally in response to anthropogenic land use, resulting from complex relationships between landscape variables and mechanisms controlling stream fish assemblages. To test for differences in regional fish response to anthropogenic land use, we conducted our study across five freshwater ecoregions in the temperate mesic portion of the United States and evaluated data characterizing stream fish assemblages from 10,522 locations across all study freshwater ecoregions. Fishes were summarized by metrics describing assemblage structure, trophic groupings of species, levels of tolerance to anthropogenic stressors, and life history characteristics, with seven metrics used for analyses. Natural and anthropogenic landscape variables were assessed across freshwater ecoregions, and we tested for regionally specific influences of percent catchment urbanization, percent catchment agriculture, and catchment densities of dams and stream-road crossings on stream fishes. We used cascade multivariate regression trees to quantify variance explained in fish metrics by these landscape variables after controlling for influences of natural landscape variables, including catchment area, catchment lithology, and elevation of study sites. Results indicated differences in dominant influences by freshwater ecoregion, as well as differences in the levels of anthropogenic land use influencing fishes within and across freshwater ecoregions. For example, urban land use was the most influential anthropogenic land use in both Appalachian Piedmont and Chesapeake Bay freshwater ecoregions, with fish assemblage metrics showing responses at 10% and 1% catchment urban land use, respectively. In contrast, dam density in the network catchment was the most influential anthropogenic variable on fish assemblage metrics in both the Laurentian Great Lakes and Middle Missouri freshwater ecoregions. Also, large amounts of agriculture in the catchment was the most influential anthropogenic land use on fish assemblage metrics in the Upper Mississippi freshwater ecoregion. Knowledge of regional differences in the top contributing anthropogenic landscape variables and the levels at which fish assemblages respond to these variables lends insight into mechanisms controlling stream fish assemblages by freshwater ecoregions and can aid in development of region-specific conservation strategies to prevent biodiversity loss from current and future anthropogenic land use.


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