Abstract
Ecological theory postulates that the size and isolation of habitat patches impact the colonization/extinction dynamics that determine community species richness and population persistence. Given the key role of lotic habitats for life-history completion in rheophilic fish, evaluating how the distribution of swift-flowing habitats affects the abundance and dynamics of subpopulations is essential. Using extensive electrofishing data, we show that merging island biogeography with meta-population theory, where lotic habitats are considered as islands in a lentic matrix, can explain spatio-temporal variation in occurrence and density of brown trout (Salmo trutta). Subpopulations in larger and less isolated lotic habitat patches had higher average densities and smaller between-year density fluctuations. Larger lotic habitat patches also had a lower predicted risk of excessive zero-catches, indicative of lower extinction risk. Trout density further increased with distance from the edge of adjacent lentic habitats with predator (Esox lucius) presence, suggesting that edge- and matrix-related mortality contributes to the observed patterns. These results can inform the prioritization of sites for habitat restoration, dam removal and reintroduction by highlighting the role of suitable habitat size and connectivity in population abundance and stability for riverine fish populations.
Highlights
Exploitation resulting in habitat fragmentation, degradation and loss constitute imminent threats to biodiversity worldwide [1,2,3,4,5,6,7,8]
Using a combination of detection–non-detection and population density data, we show that meta-population theory inspired by island biogeography can explain spatio-temporal variation in occupancy and density of brown trout, a riverine fish species present on all continents except Antarctica
Our present study of brown trout adds an important dimension to the existing knowledge contributed by these earlier studies, in that our results provide rare evidence that it is the occurrence and the density of rheophilic fish populations that increase with size and connectivity of lotic stretches
Summary
Exploitation resulting in habitat fragmentation, degradation and loss constitute imminent threats to biodiversity worldwide [1,2,3,4,5,6,7,8]. Habitat fragmentation is the process whereby continuous habitats are converted into smaller and more or less isolated habitat islands surrounded by a matrix where environmental conditions are less favourable [2,9,10] Both the size and spatial arrangement of habitat islands, the quality of the matrix and species characteristics [11] may impact the exchange of individuals between local subpopulations, with important consequences for abundance fluctuations and extinction–recolonization dynamics [12]. This forms the basis of two well-established and related theories in ecology. (d ) 3000 1000 distance to lotic stretch (m) altitude lentic stretches lotic stretches dams length along river
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
