Interactive effects of abiotic, hydrological and anthropogenic factors on fish abundance and distribution in natural run‐of‐the‐river shallow lakes

Abstract

Ecological processes in lowland rivers are mostly dominated by hydrology and its interactions with other environmental factors. Fish-habitat relationships in rivers are also influenced by human impacts.In this study, we describe patterns of abundance and distribution of fish species in a group of natural lowland river lakes along spatial anthropogenic and abiotic gradients when four hydrologically different summers are compared. We also describe the proportion of the total variances in fish species abundances that can be accounted for by selected abiotic (water conductivity), hydrological (water residence time) and human activity-derived (total phosphorus (TP) concentration and NO 3 :NH 4 ) variables. Consequently, our main purpose is to explore how abiotic and anthropogenic factors interact to affect fish abundance and distribution together with consistent results across different hydrological conditions. We conclude with a briefly discussion of some management implications.The anthropogenic impacts on water quality, the extreme hydrological variability and the fluctuating abiotic environment affected fish abundance and distribution. Pampa inland silverside Odontesthes bonariensis was benefited from a less human disturbed environment with higher water residence time and total salinity, whereas species as Cyphocharax voga, Parapimelodus valenciennis and Cyprinus carpio found these conditions largely disadvantageous. On the other hand, while most species showed stronger-either negative or positive-response to anthropogenic, hydrological or abiotic factors Oligosarcus jenynsii was only slightly affected. This paper identified the ecological function of a lowland river under its natural flow regime. There are not many opportunities to study unmodified rivers worldwide. Therefore, our findings may help in assessment programmes of fish communities in flow altered and human disturbed aquatic ecosystems.

Patterns in fish species composition and assemblage structure in the upper Salado River lakes, Pampa Plain, Argentina

“…Conversely, we considered the two main spatial axes along which these lakes may be described; a first axis of landscape human development (Rosso & Quirós, 2007) and a second abiotic axis of total salinity of their waters (Gabellone et al, 2005). Accordingly to these directive gradients, these lakes display a spatial variation in the NO 3 :NH 4 ratio and water conductivity respectively (Rosso & Quirós, 2009). …”

“…In the upper Salado River lakes, the abundance and distribution of dominant fish species have been shown to mostly follow spatial gradients in water conductivity and anthropogenic factors (Rosso & Quirós, 2009). However, it was not explored yet whether patterns in dominance and persistence of all fish species in response to these directive gradients may finally influence the richness, diversity and structure of fish assemblages in these lakes.…”

Factors affecting the distribution of fish during receding flood in lower Irtysh: effects of water level and diurnal cycle

“…It appears that such seasonal and diurnal cycles exert the major influences on the distribution and abundance of fish, whereas local habitat heterogeneity and complexity seem relatively unimportant. Habitat structure and complexity plays an important role in shaping floodplain biota, including fish (Pusey et al, 1995;Amoros and Bornette, 2002;Hohausova´et al, 2003;Rosso and Quiros, 2009). However, such effects are not always straightforward.…”

“…(Rosso and Quiros, 2009;Jackson et al, 2001;Lucas et al, 2001). It is never static and involves continuous movements, drift and migrations at various scales which change over time (e.g., seasonally) and during the diurnal cycle (Welcomme et al, 2006;.…”

“…Nonetheless, illumination alone might not be the only determining factor: local and global environmental heterogeneity, hydrological conditions as well as other factors may also exert substantial effects on fish migration and distribution (Pusey et al, 1995;Amoros and Bornette, 2002;Hohausova´et al, 2003;Rosso and Quiros, 2009). Continental subarctic water bodies, such as Siberian Rivers such as the River Irtysh, are particularly interesting albeit poorly studied in this respect due to relatively severe climatic conditions with strong seasonal (and often interannual) changes of the water temperature, nutrient availability and water supply (Lyozin, 1999;Vincent, 2008).…”