Synchrony in riverine fish populations: Regional vs. local influences on population dynamics.
BERGNER, R.*,1, BUKAVECKAS, P.1, EMERY, E.2, 1 University of Louisville, Louisville, Kentucky, USA2 Ohio River Sanitation Commission, Cincinnati, Ohio, USA
ABSTRACT- When Lewis and Clark descended the Ohio River, it flowed freely over the Great Falls at Louisville, and the 981-mile river was dotted with islands, gravel bars, marshes, and embayments. Today the Ohio River consists of a series of navigation pools regulated by 20 lock and dam structures. This study investigates synchrony of fish populations among navigation pools. We hypothesized that if recruitment was regulated by regional-scale climatic phenomena (discharge, temperature), populations would exhibit high levels of synchrony throughout the river. Alternatively, a lack of synchrony would suggest that pool-specific factors (species interactions, habitat quality) determine interannual variation in recruitment. A 25-year record (1967 - 1992) of lock chamber rotenone sampling yielded nine pairwise combinations of pools that were sampled concurrently in at least 7 years. Synchrony was measured by calculating between-pool correlation coefficients from abundance data (biomass) for six of the ten most common species: freshwater drum (Aplodinotus grunniens), skipjack herring (Alosa chrysochloris), gizzard shad (Dorosoma cepedianum), channel catfish (Ictalurus punctatus), sauger (Stizostedion canadense), and common carp (Cyprinus carpio). In all pairs, correlation coefficients were indicative of low levels of synchrony. Proximate pools did not exhibit higher levels of synchrony than distant pools although cluster analysis indicated that proximate pools were more similar in community composition. Our analyses suggest that local factors are the primary determinants of interannual variation in population abundance. The presence of engineered structures within the river channel may restrict dispersal and result in divergent community trajectories.
Key words: population dynamics, synchrony, large river systems
All materials copyright The Ecological Society of America (ESA), and may not be used without written permission.