The effect of inter-and intraspecific competition on individual and population niche widths – a four-decade study on two interacting salmonids ...
Competition is assumed to shape niche widths, affecting species survival and coexistence. Expectedly, high interspecific competition will reduce population niche widths, whereas high intraspecific competition will do the opposite. Here we test in situ how intra- and interspecific competition affects...
| Main Authors: | , , , , , , |
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| Format: | Dataset |
| Language: | English |
| Published: |
Dryad
2021
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| Subjects: | |
| Online Access: | https://dx.doi.org/10.5061/dryad.95x69p8jx https://datadryad.org/stash/dataset/doi:10.5061/dryad.95x69p8jx |
| Summary: | Competition is assumed to shape niche widths, affecting species survival and coexistence. Expectedly, high interspecific competition will reduce population niche widths, whereas high intraspecific competition will do the opposite. Here we test in situ how intra- and interspecific competition affects trophic resource use and the individual and population niche widths of two lacustrine fish species, Arctic charr and brown trout, covering a 40 year study period with highly contrasting competitive impacts prior to and following a large-scale fish culling experiment. Initially, an overcrowded Arctic charr population dominated the study system, with brown trout being nearly absent. The culling experiment reduced the littoral Arctic charr density by 80%, whereupon brown trout gradually increased its density in the system. Thus, over the study period, the Arctic charr population went from high to low intraspecific competition, followed by increasing interspecific competition with brown trout. As hypothesized, the ... : Fish sampling and processing Charr and trout were sampled annually from the littoral habitat (<15 m depth) in August from 1980 to 2019 using single-meshed gillnets of various mesh sizes prior to 1989 and thereafter multi-meshed gillnets with panels of eight different mesh sizes ranging from 10 to 45 mm, knot to knot (Table 1). The nets fished in the lake overnight for approximately 12 hours. Fork length and other parameters not used in the current study (weight, sex, and gonad maturation) of all fish were recorded in the field and stomach samples were collected. Catch per unit effort (CPUE), defined as the number of fish caught per 100 m2 gillnets per night, was estimated as a proxy for the littoral abundance of charr and trout. In the lab, stomachs were opened, and the fullness degree was determined on a scale from 0 to 100% (Amundsen and Sánchez‐Hernández 2019). Prey items were identified at the lowest taxonomical level, and their relative contribution to total stomach fullness (expressed in percentage) ... |
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