chapter  5
36 Pages

Restoring assemblages of invertebrates and fishes

Fish and invertebrates are integral and valued components of naturally functioning wetland ecosystems. Benthic invertebrates provide food-web support for consumers such as shorebirds and fish (Virnstein 1977, Schneider 1978, Quammen 1984) and influence sediment properties, including compaction (McMaster 1967), water content, and texture (Rhoads and Young 1970). Similarly, fish function as vehicles for nutrient cycling and energy transfer across habitats at a number of trophic levels in the estuarine food web (Allen 1982, Kneib 1997, Kwak and Zedler 1997). In turn, wetland habitats provide these animals with areas for refuge, reproduction, feeding, and other essential functions. For example, it is estimated that over 75% of the commercially important fish and invertebrates harvested annually in the U.S. rely upon coastal wetlands during some part of their life cycle (Chambers 1992). While many southern California wetland fish and invertebrate species are not considered commercially or recreationally important, they are vital links in the nearshore food web, serving as prey for endangered bird species, such as the California least tern (

Sterna antillarum browni

) and the light-footed clapper rail (

Rallus longirostris levipes

) (Zedler et al. 1992). Because of the important roles fish and invertebrates play in wetland ecosystems,

many restoration projects are designed to provide habitat for these groups. Typical restoration goals are to provide nursery habitat for commercially important species or foodchain support for higher trophic levels. It is often assumed that animals will recolonize a site naturally if the native plant community is present, and sites are designed to meet the needs of various plant assemblages (Chapter 4). Little attention is paid to the factors influencing animal colonization and persistence, including how humans affect the ability of native fish and invertebrates to use areas with altered water quality, introduced species, and night lighting.