科研之友
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摘要
Migratory fishes can affect tributary ecosystem properties given their potential to introduce nutrients (fertilize) and physically modify habitat (engineer) during spawning. Nonetheless, migrant effects are frequently context-dependent, and it is useful to understand their strength relative to other potential ecosystem drivers. We examined whether tributary ecosystem properties varied in response to migrations of two adfluvial salmonids, taking advantage of differences in migration timing and reproductive strategy between species, as well as hydrogeomorphic differences between a pair of tributaries. For analyses, we used a model comparison approach to evaluate migrant effects relative to other possible drivers. We observed that Bonneville cutthroat trout (Oncorhynchus clarkii utah) engineered benthic chlorophyll a in redds, with reduction (51% +/- 16% decrease) generally occurring during migrations. Contrary to expectations, migrant fertilization effects were not pronounced even in the more retentive tributary during migration by species (kokanee, Oncorhynchus nerka) that exhibited high postspawning mortality. Based on multimodel comparisons, isolated migrant effects were not the primary influence on measured ecosystem properties. Our findings underscore the need to consider different biotic and abiotic conditions that can mediate migratory fish effects.
- 出版日期2018-3
