Temporal trends and determinants of fish biomass in two contrasting natural lake systems: insights from a spring long-term monitoring scheme
| Autor: | Anastasios Bounas, Harris Nikolaou, M. Malakou, Delphine Nicolas, Irene Koutseri, Alain J. Crivelli, Giorgos Catsadorakis |
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| Rok vydání: | 2021 |
| Předmět: |
random forests
0106 biological sciences SH1-691 Introduced species Management Monitoring Policy and Law Aquatic Science 010603 evolutionary biology 01 natural sciences invasive species Lepomis Abundance (ecology) water management gillnet Aquaculture. Fisheries. Angling Nature and Landscape Conservation Water Science and Technology Trophic level Biomass (ecology) Ecology biology Overfishing 010604 marine biology & hydrobiology biology.organism_classification Habitat destruction prespa wetland Freshwater fish Environmental science |
| Zdroj: | Knowledge and Management of Aquatic Ecosystems, Vol 0, Iss 422, p 28 (2021) |
| ISSN: | 1961-9502 |
| Popis: | Freshwater fish declines are triggered by a suite of anthropogenic threats, including habitat degradation, climate and land use change, biological invasions, pollution and overfishing. Robust monitoring schemes are needed to understand and detect any effects of different factors on freshwater fish abundance and to be able to predict and respond to potential stressors. Here, we used standardized biomass-per-unit-effort (BPUE) data deriving from gillnet sampling over a 34-year period in the two Prespa Lakes and determined species trends using general additive models coupled with structural change models. Furthermore, the influence of seven environmental variables was assessed for each fish species using an analytical approach based on random forests. We showed that the total annual BPUE is increasing in Lake Mikri Prespa whereas it is stable in Megali Prespa and that the relative BPUE of introduced species in the former is increasing through the years. Differences in the lakes' trophic status were reflected in species trend patterns. Random forests showed that air temperature, the introduction of the invasive Lepomis gibbosus, predation and water management played a role in shaping species biomass in Mikri Prespa whereas abiotic factors are the main drivers of biomass changes in Megali Prespa. Our results provide empirical evidence on the importance of long-term monitoring in distinguishing between direct and indirect effects of large-scale stressors on fish abundance as well as insights towards sustaining the integrity of fish communities. |
| Databáze: | OpenAIRE |
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