Behavioral interactions and trophic overlap between invasive signal crayfish Pacifastacus leniusculus (Decapoda, Astacidae) and native fishes in iberian rivers

The signal crayfish Pacifastacus leniusculus Dana, 1852 is a successful invasive species in the Iberian Peninsula. This is of particular conservation concern, as fish fauna is highly endemic and also threatened within this ecoregion. The aim of this study was to analyze behavioral interactions and trophic overlap between signal crayfish and native fishes in Iberian rivers (northern Spain). Video cameras were used to record fish "dominance/evasion" after spatial encounters with crayfish. Diet composition and isotopic signatures (¿13C and ¿15N) were compared to evaluate the niche overlap. Fish were dominant in 25% of the encounters with juvenile crayfish, whereas this percentage was only 4% with adult crayfish. Observations showed a high fish "evasion" response for Pyrenean stone loach Barbatula quignardi (B¿cescu-Me¿ter, 1967) (>30%). Dietary results showed a high trophic overlap between signal crayfish with the pelagic Pyrenean minnow Phoxinus bigerri Kottelat, 2007 and the benthic loach. However, the isotopic niche overlap was low, with brown trout Salmo trutta L., 1758 showing the highest area (only 0.1 ¿2). Overall, our findings suggest that interferences may occur with native species for food (i.e., benthic invertebrates). Consequently, measures should be applied to control invasive crayfish in Iberian rivers

Investment in the long-tail of biodiversity data: from local research to global knowledge

In business, the "long-tail economy" refers to a market strategy where the gravity center shifts from a few high-demand products to many, varied products focused on small niches. Commercialization of individually low-demand products can be profitable as long as their production cost is low and, all taken together, they aggregate into a big chunk of the market. Similarly, in the "business" of biodiversity data acquisition, we can find several mainstream products that produce zillions of bits of information every year and account for most of the budget allocated to increase our primary data-based knowledge about Earth's biological diversity. These products play a crucial role in biodiversity research. However, along with these large global projects, there is a constellation of small-scale institutions that work locally, but whose contribution to our understanding of natural processes should not be dismissed. These information datasets can be collectively referred to as the "long-tail biodiversity data"

A new method to include fish biodiversity in river connectivity indices with applications in dam impact assessments

Different indices have been developed to quantify the extent and severity of river fragmentation. These indices vary depending on the specific goals of the study. Here, we present a new Conservation Connectivity Index (CCIP) for potamodromous fish species that considers the conservation value (richness, rarity and vulnerability) of river segments. The Iberian Peninsula holds > 20 endemic and endangered potamodromous fish species as well as > 1000 large dams (> 1 hm3 of capacity). The CCIP was calculated for the eight most important river basins of the Iberian Peninsula and compared to the Dendritic Connectivity Index (DCIP) developed by Cote et al. in 2009, which uses only river length as a habitat variable. With the use of both DCIP and CCIP, the dams were analysed and ranked according to their impacts on the river basin. The main results show that Iberian river basins are heavily fragmented, with river basin connectivity percentages of less than 20% in most cases using both DCIP and CCIP. CCIP values are slightly higher than DCIP values in almost all cases. When the impact of individual dams is analysed, differences also appear between the DCIP and CCIP. CCIP highlights the impact of dams located in areas of high fish conservation value while DCIP emphasize the impact of dams fragmenting large river segments. The CCIP appears to be adequate to highlight important sites for conservation in river connectivity studies. It could be applied in different studies and river basins around the world to prioritize dam removals or plan new dam locations

A new method to include fish biodiversity in river connectivity indices with applications in dam impact assessments

Different indices have been developed to quantify the extent and severity of river fragmentation. These indices vary depending on the specific goals of the study. Here, we present a new Conservation Connectivity Index (CCIP) for potamodromous fish species that considers the conservation value (richness, rarity and vulnerability) of river segments. The Iberian Peninsula holds > 20 endemic and endangered potamodromous fish species as well as > 1000 large dams (> 1 hm3 of capacity). The CCIP was calculated for the eight most important river basins of the Iberian Peninsula and compared to the Dendritic Connectivity Index (DCIP) developed by Cote et al. in 2009, which uses only river length as a habitat variable. With the use of both DCIP and CCIP, the dams were analysed and ranked according to their impacts on the river basin. The main results show that Iberian river basins are heavily fragmented, with river basin connectivity percentages of less than 20% in most cases using both DCIP and CCIP. CCIP values are slightly higher than DCIP values in almost all cases. When the impact of individual dams is analysed, differences also appear between the DCIP and CCIP. CCIP highlights the impact of dams located in areas of high fish conservation value while DCIP emphasize the impact of dams fragmenting large river segments. The CCIP appears to be adequate to highlight important sites for conservation in river connectivity studies. It could be applied in different studies and river basins around the world to prioritize dam removals or plan new dam locations

Behavioral interactions and trophic overlap between invasive signal crayfish Pacifastacus leniusculus (Decapoda, Astacidae) and native fishes in iberian rivers

The signal crayfish Pacifastacus leniusculus Dana, 1852 is a successful invasive species in the Iberian Peninsula. This is of particular conservation concern, as fish fauna is highly endemic and also threatened within this ecoregion. The aim of this study was to analyze behavioral interactions and trophic overlap between signal crayfish and native fishes in Iberian rivers (northern Spain). Video cameras were used to record fish "dominance/evasion" after spatial encounters with crayfish. Diet composition and isotopic signatures (¿13C and ¿15N) were compared to evaluate the niche overlap. Fish were dominant in 25% of the encounters with juvenile crayfish, whereas this percentage was only 4% with adult crayfish. Observations showed a high fish "evasion" response for Pyrenean stone loach Barbatula quignardi (B¿cescu-Me¿ter, 1967) (>30%). Dietary results showed a high trophic overlap between signal crayfish with the pelagic Pyrenean minnow Phoxinus bigerri Kottelat, 2007 and the benthic loach. However, the isotopic niche overlap was low, with brown trout Salmo trutta L., 1758 showing the highest area (only 0.1 ¿2). Overall, our findings suggest that interferences may occur with native species for food (i.e., benthic invertebrates). Consequently, measures should be applied to control invasive crayfish in Iberian rivers