Flood-induced interspecific interactions in spring-fed tributary as an ecosystem function of heterogeneous river networks

Understanding the migratory community dynamics of river networks is important for maintaining lotic system integrity. River animals migrate to their preferred habitats in spatiotemporally heterogeneous river environments. Spring-fed habitats are uniquely characterized by stable temperature and flow...

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Bibliographic Details
Published in:Landscape and ecological engineering 2021-10, Vol.17 (4), p.555-561
Main Authors: Sakai, Masaru, Wakiya, Ryoshiro, Hoshi, Gosuke
Format: Article
Language:English
Subjects:
Accumulation
Anadromous species
Animals
Aquatic ecosystems
Biomedical and Life Sciences
Civil Engineering
Consumption
Eggs
Environmental Management
Fish eggs
Floods
Habitats
Interspecific relationships
Landscape Ecology
Landscape/Regional and Urban Planning
Life Sciences
Nature Conservation
Oncorhynchus keta
Oncorhynchus masou masou
Plant Ecology
Population density
Rainfall
Rainfall intensity
River networks
Rivers
Salmon
Short Communication
Spawning
Spring
Spring (season)
Tributaries
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Summary:Understanding the migratory community dynamics of river networks is important for maintaining lotic system integrity. River animals migrate to their preferred habitats in spatiotemporally heterogeneous river environments. Spring-fed habitats are uniquely characterized by stable temperature and flow regimes, which create suitable spawning habitats for the chum salmon Oncorhynchus keta . O. keta exhibits “run up” to its birthplace for spawning, especially during floods. Because the eggs deposited by this anadromous fish are nutritious and actively consumed by freshwater animals, the location and timing of O. keta spawning events affect the spatiotemporal accumulation of mobile consumers. In this study, we examined changes in temporal population density in spawning O. keta and a mobile consumer (juvenile O. masou masou ) in a lowland, spring-fed tributary in northern Japan during a 48.5-mm autumn rainfall event. In both species, population density increased, and then decreased, after the rainfall event. In O. keta , these changes were closely associated with rainfall intensity, whereas in O. masou masou the peak was delayed until 3 days after the rainfall event. A comparison of the gut contents of O. masou masou sampled from a spring-fed tributary and an adjacent non-spring-fed tributary indicated greater consumption of O. keta eggs in the spring-fed tributary. These results suggested that preferential migration of O. keta into spring-fed tributaries for spawning induces subsequent accumulation of juvenile O. masou masou , in turn increasing O. keta egg consumption. These findings improve our understanding of community dynamics during floods in a heterogeneous river network environment.
ISSN:1860-1871
1860-188X
DOI:10.1007/s11355-021-00465-8