CONTRIBUTIONS TO UNDERSTANDING SEAWEEDS IN COASTAL COMMUNITIES

Abstract

Dawes, C. J.Department of Biology, University of South Florida, Tampa, Florida 33620The goal of my presentation is to review several studies that have enhanced our understanding of the effects of abiotic factors on coastal and estuarine seaweed populations. Accordingly, I will introduce a few key papers dealing with five major abiotic factors‐i.e. salinity, temperature, desiccation, water motion, and illumination. Foremost, the salinity tolerance studies of Russell and Bolton (1975) have broad applicability to estuarine seaweeds, while the osmoregulatory studies of Bisson and Kirst (1979) are also significant. Biebl's (1972) review of his earlier studies on temperature tolerances in diverse seaweeds were pivotal. Johnston and Raven's (1986) studied the effects of desiccation on the fucoid brown alga Ascophyllum nodosum, while similar studies on the saccate brown seaweed Colpomenia peregrina were conducted by Oates (1985). Lewis (1968) conducted early synoptic evaluations of the effects of water movement on rocky shore communities, while Kitching and Ebling (1967) gave detailed assessments of seaweed populations within estuarine tidal rapids in Ireland. Basically estuarine tidal rapids represent areas of enhanced nutrients, oxygen and light availability, plus reduced sedimentation (Mathieson et al. (1983). The physiological effects of light have probably been evaluated more than any single abiotic factor and two areas of importance are cited here. The critical papers by Levring (1947) on submarine illumination and those of Ramus (1978) and Littler and Littler (1980) on algal form and light response. Several areas of future studies are also suggested, which may further enhance our understanding of seaweed adaptations. In summary, five major abiotic factors affecting coastal and estuarine seaweed populations will be discussed, their importance to seaweeds noted, and “key” findings for several significant papers summarized.