Effect of a change in physical structure and cover on fish and fish habitat in freshwater ecosystems – a review and meta-analysis

Abstract

Aquatic resource managers are continually faced with construction or site development proposals which, if allowed to proceed, would ultimately alter the physical structure and cover of fish habitat. In the absence of clear quantitative guidelines linking the change in habitat to fish, resource managers often use the change in habitat area as a basis for decisions. To assess the weight of scientific evidence in support of management decisions, we summarized both the observational and experimental freshwater fish-habitat literature. We then extracted data from experimental studies (where possible) for inclusion in a meta-analysis, to provide a more rigorous assessment of the published results of experimental habitat manipulations. We found relatively strong and consistent correlational evidence linking fish and physical habitat features, yet inconsistent evidence when narratively reviewing the experimental literature. On the whole, decreases in structural habitat complexity are detrimental to fish diversity and can change species composition. Increases in structural complexity showed increases, decreases, or no measurable changes in species and (or) communities. The majority of our meta-analyses resulted in supporting a direct link between habitat and fish abundance or biomass, with fish biomass responding most strongly to habitat change. Habitat alterations are most likely to affect individual species or community structure, and thus evaluating the extent of the effect on a biological basis depends on management objectives.

Wood placement in river restoration: fact, fiction, and future direction

“…For example, reviews of the literature on effectiveness of instream habitat improvement and wood placement have reported significant improvements in physical habitat (pool area and cover) and localized juvenile or adult fish abundance (Roni et al 2002(Roni et al , 2008Smokorowski and Pratt 2007). These studies generally conclude that wood placement leads to physical habitat change, which produced localized increases in fish abundance.…”

Effect of removal of free-floating macrophytes on zooplankton habitat in shallow wetland

“…Macrophytes can have dramatic effects on the physical structure of aquatic habitats (O'Hare et al, 2006;Smokorowski and Pratt, 2007) and create a heterogeneous mosaic at different scales. Some studies have suggested that structural heterogeneity of macrophytes mediates trophic interactions among various biota (Jeppesen et al, 1997;Pelicice and Agostinho, 2006) and significantly influences the biodiversity of the zooplankton community (Tolonen et al, 2005).…”

Factors and Processes Affecting Levee System Vulnerability

“…25 Benefits to salmonids have been a primary focus, but benefits to native and non-native species requires evaluation. These structural modifications provide overhanging riparian vegetation, (i.e., shaded riverine aquatic) slower water velocities, and soft bank substrates, which may offer important protective and feeding habitat for migrating juvenile salmon (Murphy and Meehan 1991;Smokorowski and Pratt 2007 Levees that are set back a substantial distance from channels can facilitate restoration of natural riverine processes and provide broad areas of floodplain habitat that benefit aquatic and terrestrial target species (Golet et al 2013). Davenport et al (2016) assessed 15 Delta leveerelated habitat improvement projects.…”