SYLVAIN MASTRORILLO - Profile on Academia.edu (original) (raw)
Papers by SYLVAIN MASTRORILLO
Belgian Journal of Zoology, Feb 1, 2004
Human population growth, urbanisation and conversion of land to agriculture have led to loss of n... more Human population growth, urbanisation and conversion of land to agriculture have led to loss of natural wetlands throughout the World, making artificial wetlands such as gravel pits, dam lakes or rice fields important for waterbirds. In south-west France, the increasing abundance of gravel pits has allowed several bird species to colonize the region. These "new" wetlands have become substitutes for the natural habitats of waterbirds. Coots ( Fulica atra L. 1758) colonised the Midi-Pyrénées area when gravel pits were created in the 1970's. Coot populations were censused weekly from on three gravel pits near Toulouse, SW France. Each winter, the number of coots was recorded on each gravel pit, and the microhabitat used by coots identified according to environmental variables (water depth, bank slope, bank vegetation, vegetation between watermarks, macrophytes, human disturbance, zones of open water or near the bank). Open water, which constitutes a secure habitat for this species during the wintering period, abundance of macrophytes (Characea) and presence of lawn on the bank appear as the most important factors influencing coot distribution. This information will be useful for site acquisition for nature conservation and management purposes.
Hydrobiologia, Jul 31, 2005
We investigated the relationships between different environmental variables and the spatial distr... more We investigated the relationships between different environmental variables and the spatial distribution patterns of the stoneloach (Barbatula barbatula) at the stream system, the stream site, and the mesohabitat (riffle/pool) scales in south-western France. Stoneloach occurred at 240 sites (out of 554 sampling sites), chiefly close to the source, in areas at low elevation and with weak slopes. Population density at a site was primarily influenced by physical conditions. Stream width was positively related to the probability of presence of stoneloach within the stream system, but negatively related to local density. These results indicate that stoneloaches can occur in a wide range of streams, but they are less abundant in wide rivers, probably because of lower habitat heterogeneity. Slope was negatively correlated to both fish presence at the regional scale and local density, suggesting that stoneloach's swimming performance were weak under greater erosive forces. These results suggested that the distribution of populations and the density of stoneloach were governed by the suitability of physical habitat. Multi-scale studies of factors influencing a species' distribution allow to integrate patterns observed at different scales, and enhance our understanding of interactions between animals and their environment. The use of few pertinent variables in successful final models could reduce the effort and cost of data collection for water management applications.
Co-occurrence Patterns of Some Small-bodied Freshwater Fishes in Southwestern France: Implications for Fish Conservation and Environmental Management
Ambio a Journal of the Human Environment, Sep 1, 2005
We assessed the influence of environmental variables (elevation, stream order, distance from sour... more We assessed the influence of environmental variables (elevation, stream order, distance from source, catchment area, slope, stream width, and fish species richness) on the co-occurrence patterns of the minnow, the stone loach, and the gudgeon at the stream system scale. A total of 474 sites were classified according to the seven variables using the Self-Organizing Map (neural network), and three clusters were detected (k-means algorithm). The frequency of the various fish co-occurrence patterns was calculated for each cluster, and general linear modeling was used to specify the conditions that predict the occurrence of each species. Piedmont streams were more likely to support coexisting gudgeon and minnow populations because of higher probabilities of occurrence for both species. The higher co-occurrence frequency for the three species together in headwater streams resulted from lower occurrence frequencies in gudgeon and minnow. Focusing on areas that favor the co-occurrence of species may enhance the effectiveness of conservation projects.
Archives of Environmental Contamination and Toxicology, Nov 1, 1997
Riverine ecosystems are subject to a large variety of man-made influences, and in recent years a ... more Riverine ecosystems are subject to a large variety of man-made influences, and in recent years a new public awareness of the need to protect rivers has emerged within the industrialized world. The present study focuses on the effect of abatement of pollution from one factory on the recovery of fish and macroinvertebrate species richness in the River Petite Baïse over a 20-year period . Until 1973, the Petite Baïse (75 km in length) received not only factory waste (nitrogenous rich effluents) but also the untreated sewage of many villages and agricultural runoff from the river's catchment. In 1970, macroinvertebrates and fishes were absent in the river despite having initially been classified as of the barbel Barbus barbus zone, and extensive efforts were made by the factory to reduce pollution to allow the riverine community to recover. Regular surveys between 1973 and 1993 revealed a progressive improvement in water quality and the recolonization of the river by macrobenthic and fish populations. Macrobenthic fauna species richness gradually increased from zero in 1970 to level 8 or 9 in 1993 (Verneaux and Tuffery method), reflecting improvements in river water quality. Fish were not observed until 40 km downstream of the factory in 1978, 16 km in 1980, and approximately 5 km by 1990. Fish species richness increased from five in 1978 (barbel, chub Leuciscus cephalus, stone loach Barbatula barbatula, minnow Phoxinus phoxinus, gudgeon Gobio gobio) to eight in 1990 (the carnivorous brown trout Salmo fario, the omnivorous chub, and six benthophagous fishes: gudgeon, barbel, minnow, stone loach, sofie Chondrostoma toxostoma, carp Cyprinus carpio). Fish biomass 45 km downstream the factory increased from 1 g/m 2 in 1978 to more than 5 g/m 2 by 1990. Recolonization of the river, in particular those areas furthest downstream from the factory, occurred as a result of reductions in the nitrogen inputs emanating from the factory.
Gravel pits as new wetlands for the little grebe Tachybaptus ruficollis
Vie Et Milieu, 2004
Microhabitat use by 0+ brown trout (Salmo trutta L.) in a mountain stream affected by hydropeaking operations (Pyrénées, Southeast France)
River Systems, 2001
Biological Conservation
Our ability to demonstrate statistical patterns of invasion by non-native species will determine ... more Our ability to demonstrate statistical patterns of invasion by non-native species will determine the success of future management projects. We investigated the suitability of self-organizing maps (SOM, neural network) for patterning habitat invasion by exotic fish species at the regional scale (Southwest France), using a binary dataset of species occurrences. The SOM visualization can be used as an analytical tool to bring out relationships between sample locations and biological variables, but in addition the weight of each species in the output of the SOM can be interpreted as its occurrence probability in various geographic areas. After training the SOM with fish presence/absence data, the k-means algorithm helped to derive three major clusters of sites (headwater, montane, and plain areas). Each cluster was divided into two subsets of sites according to non-native fish, because assemblage compositions delineated different geological areas: Pyrenees Mountains, Massif Central Moun...
Community structure and habitat use of 0+ riverine fish-Microhabitat use by 0+ brown trout (Salmo trutta L.) in a mountain stream affected by hydropeaking operations (Pyrenees, Southeast France)
Gravel pits as new wetlands for the little grebe Tachybaptus ruficollis
Interaction between fish and waterbird communities: a case study of two gravel pits in south-west France
Human population growth, urbanisation and conversion of land to agriculture have led to loss of n... more Human population growth, urbanisation and conversion of land to agriculture have led to loss of natural wetlands throughout the World, making artificial wetlands such as gravel pits, dam lakes or rice fields important for waterbirds. In south-west France, the increasing abundance of gravel pits has allowed several bird species to colonize the region. These "new" wetlands have become substitutes for the natural habitats of waterbirds. Coots ( Fulica atra L. 1758) colonised the Midi-Pyrénées area when gravel pits were created in the 1970's. Coot populations were censused weekly from on three gravel pits near Toulouse, SW France. Each winter, the number of coots was recorded on each gravel pit, and the microhabitat used by coots identified according to environmental variables (water depth, bank slope, bank vegetation, vegetation between watermarks, macrophytes, human disturbance, zones of open water or near the bank). Open water, which constitutes a secure habitat for this species during the wintering period, abundance of macrophytes (Characea) and presence of lawn on the bank appear as the most important factors influencing coot distribution. This information will be useful for site acquisition for nature conservation and management purposes.
Profils Ecologiques Du Vairon(Phoxinus Phoxinus L.), De La Loche Franche(Barbatula Barbatula L.) et Du Goujon(Gobio Gobio L.) a L'Echelle Du Microhabitat Dans Trois Rivieres Pyreneennes
Microhabitat use by minnow, gudgeon and stone loach in three rivers in southwestern France
Water Research, 2011
Periphyton Biofilm architecture Biofilm deformation Voltammetry Electrochemistry a b s t r a c t ... more Periphyton Biofilm architecture Biofilm deformation Voltammetry Electrochemistry a b s t r a c t The present study examined the relevance of an electrochemical method based on a rotating disk electrode (RDE) to assess river biofilm thickness and elasticity. An in situ colonisation experiment in the River Garonne (France) in August 2009 sought to obtain natural river biofilms exhibiting differentiated architecture. A constricted pipe providing two contrasted flow conditions (about 0.1 and 0.45 m s À1 in inflow and constricted sections respectively) and
Science of The Total Environment, 2014
We produced river biofilms in 2 mean temperature conditions: 17 vs 19.5°C.
Science of The Total Environment, 2012
Denitrification is an ecosystem service of nitrogen load regulation along the terrestrial-freshwa... more Denitrification is an ecosystem service of nitrogen load regulation along the terrestrial-freshwater-marine continuum. The present study documents the short-term temperature sensitivity of denitrification enzyme activity in phototrophic river biofilms as a typical microbial assemblage of this continuum. Denitrification measurements were performed using the acetylene inhibition method at four incubation temperatures: 1.1, 12.1, 21.2 and 30.9°C. For this range of temperature, N 2 O production could be fitted to an exponential function of incubation temperature, yielding mean (± standard error) activation energy of 1.42 (±0.24) eV and Q 10 of 7.0 (± 1.4). This first quantification of denitrification enzyme activity temperature dependence in phototrophic river biofilms compares with previous studies performed in soils and sediments. This demonstrates the high temperature dependence of denitrification as compared to other community-level metabolisms such as respiration or photosynthesis. This result suggests that global warming can unbalance natural community metabolisms in phototrophic river biofilms and affect their biogeochemical budget.
Spatial patterns of the biological traits of freshwater fish communities in south-west France
Journal of Fish Biology, 2005
ABSTRACT Spatial patterns in the combinations of biological traits of fish communities were studi... more ABSTRACT Spatial patterns in the combinations of biological traits of fish communities were studied in the Garonne River system (57 000 km2, south-west France). Fish species assemblages were recorded at 554 sampling sites, and the biological traits of species were described using a fuzzy-coding method. A co-inertia analysis of species distributions and biological traits identified some spatial patterns of species trait combinations. Fish species richness progressively increased from up- to downstream sections, and the longitudinal patterns of fish assemblages partitioned the river into clear biogeographic areas, such as the brown trout Salmo trutta(headwater streams), the grayling Thymallus thymallus, the barbel Barbus barbus and the bream Abramis brama zones (most downstream sections), which fitted with Huet's well-known zonation for western European rivers. Only a few biological traits, chiefly related to life-history attributes, significantly influenced the observed fish distributions. Fecundity, potential size, maximum age and reproductive factor increased from headwater to plain reaches. As a theoretical framework for assessing and predicting the functional organization of stream fish communities, spatial variations in species traits can be related to habitat conditions, thus providing explicit spatial schemes that may be useful to the design of both scientific studies and river management.
Ontogenetic Microhabitat Shifts in the Bullhead,Cottus gobio L.,in a Fast Flowing Stream
International Review of Hydrobiology, 2005
... of good biological quality (see the fish database at http://www.fishbase.org/), eg, having sa... more ... of good biological quality (see the fish database at http://www.fishbase.org/), eg, having salmonid fish and polluosensitive insects (Ephemeroptera, Plecoptera and Trichop-tera). Many factors, closely related to the destruction of physical and hydraulic stream habi-tats by man ...
International Review of Hydrobiology, 2004
The aim of this study was to investigate the influence of 5 typological variables on the spatial ... more The aim of this study was to investigate the influence of 5 typological variables on the spatial distribution patterns of fish species richness in south-western France, and, subsequently, to analyse differences in the number of species occurring in 6 major hydroregions located within the overall study area. The data were collected at 329 sampling sites. General Linear Modelling was used to assess the influence of each typological variable on local fish species richness, and to determine the differences in local fish species richness between the 6 hydroregions. Local species richness was significantly influenced by altitude, slope and catchment area, whereas distance from the source and stream width showed no significant relations with local richness. The Côteaux de Gascogne hydroregion had a significantly lower species richness, whereas no significant differences occurred among other neighbouring hydroregions. These results were congruent with the spatial distribution patterns of freshwater invertebrate species richness in the area, which were analysed in previous studies. At such a regional scale, we suggest that congruent patterns between fish and invertebrate species richness are almost certainly a result of similar responses by different taxa to environmental conditions, rather than to biotic interactions.
Belgian Journal of Zoology, Feb 1, 2004
Human population growth, urbanisation and conversion of land to agriculture have led to loss of n... more Human population growth, urbanisation and conversion of land to agriculture have led to loss of natural wetlands throughout the World, making artificial wetlands such as gravel pits, dam lakes or rice fields important for waterbirds. In south-west France, the increasing abundance of gravel pits has allowed several bird species to colonize the region. These "new" wetlands have become substitutes for the natural habitats of waterbirds. Coots ( Fulica atra L. 1758) colonised the Midi-Pyrénées area when gravel pits were created in the 1970's. Coot populations were censused weekly from on three gravel pits near Toulouse, SW France. Each winter, the number of coots was recorded on each gravel pit, and the microhabitat used by coots identified according to environmental variables (water depth, bank slope, bank vegetation, vegetation between watermarks, macrophytes, human disturbance, zones of open water or near the bank). Open water, which constitutes a secure habitat for this species during the wintering period, abundance of macrophytes (Characea) and presence of lawn on the bank appear as the most important factors influencing coot distribution. This information will be useful for site acquisition for nature conservation and management purposes.
Hydrobiologia, Jul 31, 2005
We investigated the relationships between different environmental variables and the spatial distr... more We investigated the relationships between different environmental variables and the spatial distribution patterns of the stoneloach (Barbatula barbatula) at the stream system, the stream site, and the mesohabitat (riffle/pool) scales in south-western France. Stoneloach occurred at 240 sites (out of 554 sampling sites), chiefly close to the source, in areas at low elevation and with weak slopes. Population density at a site was primarily influenced by physical conditions. Stream width was positively related to the probability of presence of stoneloach within the stream system, but negatively related to local density. These results indicate that stoneloaches can occur in a wide range of streams, but they are less abundant in wide rivers, probably because of lower habitat heterogeneity. Slope was negatively correlated to both fish presence at the regional scale and local density, suggesting that stoneloach's swimming performance were weak under greater erosive forces. These results suggested that the distribution of populations and the density of stoneloach were governed by the suitability of physical habitat. Multi-scale studies of factors influencing a species' distribution allow to integrate patterns observed at different scales, and enhance our understanding of interactions between animals and their environment. The use of few pertinent variables in successful final models could reduce the effort and cost of data collection for water management applications.
Co-occurrence Patterns of Some Small-bodied Freshwater Fishes in Southwestern France: Implications for Fish Conservation and Environmental Management
Ambio a Journal of the Human Environment, Sep 1, 2005
We assessed the influence of environmental variables (elevation, stream order, distance from sour... more We assessed the influence of environmental variables (elevation, stream order, distance from source, catchment area, slope, stream width, and fish species richness) on the co-occurrence patterns of the minnow, the stone loach, and the gudgeon at the stream system scale. A total of 474 sites were classified according to the seven variables using the Self-Organizing Map (neural network), and three clusters were detected (k-means algorithm). The frequency of the various fish co-occurrence patterns was calculated for each cluster, and general linear modeling was used to specify the conditions that predict the occurrence of each species. Piedmont streams were more likely to support coexisting gudgeon and minnow populations because of higher probabilities of occurrence for both species. The higher co-occurrence frequency for the three species together in headwater streams resulted from lower occurrence frequencies in gudgeon and minnow. Focusing on areas that favor the co-occurrence of species may enhance the effectiveness of conservation projects.
Archives of Environmental Contamination and Toxicology, Nov 1, 1997
Riverine ecosystems are subject to a large variety of man-made influences, and in recent years a ... more Riverine ecosystems are subject to a large variety of man-made influences, and in recent years a new public awareness of the need to protect rivers has emerged within the industrialized world. The present study focuses on the effect of abatement of pollution from one factory on the recovery of fish and macroinvertebrate species richness in the River Petite Baïse over a 20-year period . Until 1973, the Petite Baïse (75 km in length) received not only factory waste (nitrogenous rich effluents) but also the untreated sewage of many villages and agricultural runoff from the river's catchment. In 1970, macroinvertebrates and fishes were absent in the river despite having initially been classified as of the barbel Barbus barbus zone, and extensive efforts were made by the factory to reduce pollution to allow the riverine community to recover. Regular surveys between 1973 and 1993 revealed a progressive improvement in water quality and the recolonization of the river by macrobenthic and fish populations. Macrobenthic fauna species richness gradually increased from zero in 1970 to level 8 or 9 in 1993 (Verneaux and Tuffery method), reflecting improvements in river water quality. Fish were not observed until 40 km downstream of the factory in 1978, 16 km in 1980, and approximately 5 km by 1990. Fish species richness increased from five in 1978 (barbel, chub Leuciscus cephalus, stone loach Barbatula barbatula, minnow Phoxinus phoxinus, gudgeon Gobio gobio) to eight in 1990 (the carnivorous brown trout Salmo fario, the omnivorous chub, and six benthophagous fishes: gudgeon, barbel, minnow, stone loach, sofie Chondrostoma toxostoma, carp Cyprinus carpio). Fish biomass 45 km downstream the factory increased from 1 g/m 2 in 1978 to more than 5 g/m 2 by 1990. Recolonization of the river, in particular those areas furthest downstream from the factory, occurred as a result of reductions in the nitrogen inputs emanating from the factory.
Gravel pits as new wetlands for the little grebe Tachybaptus ruficollis
Vie Et Milieu, 2004
Microhabitat use by 0+ brown trout (Salmo trutta L.) in a mountain stream affected by hydropeaking operations (Pyrénées, Southeast France)
River Systems, 2001
Biological Conservation
Our ability to demonstrate statistical patterns of invasion by non-native species will determine ... more Our ability to demonstrate statistical patterns of invasion by non-native species will determine the success of future management projects. We investigated the suitability of self-organizing maps (SOM, neural network) for patterning habitat invasion by exotic fish species at the regional scale (Southwest France), using a binary dataset of species occurrences. The SOM visualization can be used as an analytical tool to bring out relationships between sample locations and biological variables, but in addition the weight of each species in the output of the SOM can be interpreted as its occurrence probability in various geographic areas. After training the SOM with fish presence/absence data, the k-means algorithm helped to derive three major clusters of sites (headwater, montane, and plain areas). Each cluster was divided into two subsets of sites according to non-native fish, because assemblage compositions delineated different geological areas: Pyrenees Mountains, Massif Central Moun...
Community structure and habitat use of 0+ riverine fish-Microhabitat use by 0+ brown trout (Salmo trutta L.) in a mountain stream affected by hydropeaking operations (Pyrenees, Southeast France)
Gravel pits as new wetlands for the little grebe Tachybaptus ruficollis
Interaction between fish and waterbird communities: a case study of two gravel pits in south-west France
Human population growth, urbanisation and conversion of land to agriculture have led to loss of n... more Human population growth, urbanisation and conversion of land to agriculture have led to loss of natural wetlands throughout the World, making artificial wetlands such as gravel pits, dam lakes or rice fields important for waterbirds. In south-west France, the increasing abundance of gravel pits has allowed several bird species to colonize the region. These "new" wetlands have become substitutes for the natural habitats of waterbirds. Coots ( Fulica atra L. 1758) colonised the Midi-Pyrénées area when gravel pits were created in the 1970's. Coot populations were censused weekly from on three gravel pits near Toulouse, SW France. Each winter, the number of coots was recorded on each gravel pit, and the microhabitat used by coots identified according to environmental variables (water depth, bank slope, bank vegetation, vegetation between watermarks, macrophytes, human disturbance, zones of open water or near the bank). Open water, which constitutes a secure habitat for this species during the wintering period, abundance of macrophytes (Characea) and presence of lawn on the bank appear as the most important factors influencing coot distribution. This information will be useful for site acquisition for nature conservation and management purposes.
Profils Ecologiques Du Vairon(Phoxinus Phoxinus L.), De La Loche Franche(Barbatula Barbatula L.) et Du Goujon(Gobio Gobio L.) a L'Echelle Du Microhabitat Dans Trois Rivieres Pyreneennes
Microhabitat use by minnow, gudgeon and stone loach in three rivers in southwestern France
Water Research, 2011
Periphyton Biofilm architecture Biofilm deformation Voltammetry Electrochemistry a b s t r a c t ... more Periphyton Biofilm architecture Biofilm deformation Voltammetry Electrochemistry a b s t r a c t The present study examined the relevance of an electrochemical method based on a rotating disk electrode (RDE) to assess river biofilm thickness and elasticity. An in situ colonisation experiment in the River Garonne (France) in August 2009 sought to obtain natural river biofilms exhibiting differentiated architecture. A constricted pipe providing two contrasted flow conditions (about 0.1 and 0.45 m s À1 in inflow and constricted sections respectively) and
Science of The Total Environment, 2014
We produced river biofilms in 2 mean temperature conditions: 17 vs 19.5°C.
Science of The Total Environment, 2012
Denitrification is an ecosystem service of nitrogen load regulation along the terrestrial-freshwa... more Denitrification is an ecosystem service of nitrogen load regulation along the terrestrial-freshwater-marine continuum. The present study documents the short-term temperature sensitivity of denitrification enzyme activity in phototrophic river biofilms as a typical microbial assemblage of this continuum. Denitrification measurements were performed using the acetylene inhibition method at four incubation temperatures: 1.1, 12.1, 21.2 and 30.9°C. For this range of temperature, N 2 O production could be fitted to an exponential function of incubation temperature, yielding mean (± standard error) activation energy of 1.42 (±0.24) eV and Q 10 of 7.0 (± 1.4). This first quantification of denitrification enzyme activity temperature dependence in phototrophic river biofilms compares with previous studies performed in soils and sediments. This demonstrates the high temperature dependence of denitrification as compared to other community-level metabolisms such as respiration or photosynthesis. This result suggests that global warming can unbalance natural community metabolisms in phototrophic river biofilms and affect their biogeochemical budget.
Spatial patterns of the biological traits of freshwater fish communities in south-west France
Journal of Fish Biology, 2005
ABSTRACT Spatial patterns in the combinations of biological traits of fish communities were studi... more ABSTRACT Spatial patterns in the combinations of biological traits of fish communities were studied in the Garonne River system (57 000 km2, south-west France). Fish species assemblages were recorded at 554 sampling sites, and the biological traits of species were described using a fuzzy-coding method. A co-inertia analysis of species distributions and biological traits identified some spatial patterns of species trait combinations. Fish species richness progressively increased from up- to downstream sections, and the longitudinal patterns of fish assemblages partitioned the river into clear biogeographic areas, such as the brown trout Salmo trutta(headwater streams), the grayling Thymallus thymallus, the barbel Barbus barbus and the bream Abramis brama zones (most downstream sections), which fitted with Huet's well-known zonation for western European rivers. Only a few biological traits, chiefly related to life-history attributes, significantly influenced the observed fish distributions. Fecundity, potential size, maximum age and reproductive factor increased from headwater to plain reaches. As a theoretical framework for assessing and predicting the functional organization of stream fish communities, spatial variations in species traits can be related to habitat conditions, thus providing explicit spatial schemes that may be useful to the design of both scientific studies and river management.
Ontogenetic Microhabitat Shifts in the Bullhead,Cottus gobio L.,in a Fast Flowing Stream
International Review of Hydrobiology, 2005
... of good biological quality (see the fish database at http://www.fishbase.org/), eg, having sa... more ... of good biological quality (see the fish database at http://www.fishbase.org/), eg, having salmonid fish and polluosensitive insects (Ephemeroptera, Plecoptera and Trichop-tera). Many factors, closely related to the destruction of physical and hydraulic stream habi-tats by man ...
International Review of Hydrobiology, 2004
The aim of this study was to investigate the influence of 5 typological variables on the spatial ... more The aim of this study was to investigate the influence of 5 typological variables on the spatial distribution patterns of fish species richness in south-western France, and, subsequently, to analyse differences in the number of species occurring in 6 major hydroregions located within the overall study area. The data were collected at 329 sampling sites. General Linear Modelling was used to assess the influence of each typological variable on local fish species richness, and to determine the differences in local fish species richness between the 6 hydroregions. Local species richness was significantly influenced by altitude, slope and catchment area, whereas distance from the source and stream width showed no significant relations with local richness. The Côteaux de Gascogne hydroregion had a significantly lower species richness, whereas no significant differences occurred among other neighbouring hydroregions. These results were congruent with the spatial distribution patterns of freshwater invertebrate species richness in the area, which were analysed in previous studies. At such a regional scale, we suggest that congruent patterns between fish and invertebrate species richness are almost certainly a result of similar responses by different taxa to environmental conditions, rather than to biotic interactions.