Growth And Competition Of Anadyomene In Biscayne Bay, Florida

Abstract

Increasing cover of drift algae (Anadyomene spp.) within Biscayne Bay prompted the evaluation of species-specific growth characteristics and competitive abilities. The algae have been growing abundantly and depleting seagrass beds within certain areas of the bay. In this study, the growth of both A. stellata and A. pavonina were measured as change in wet weight using laboratory manipulations of salinity and nutrient concentrations. Salinities tested ranged from 10-40 ppt and growth rates were significantly higher at 20 ppt. Nutrient enrichments (Low:+1mM P/+10mM N, High:+2mM P/+20mM N) also significantly increased the growth rate above ambient water at both treatment levels. Competition and productivity were evaluated using in situ caging experiments with a control, low (10L wet volume) and high algal (20L wet volume) cover treatment. PAR, seagrass percent cover, epiphyte coverage and growth rate of underlying seagrasses were measured. PAR, seagrass percent cover and growth rate were significantly correlated to algal mass within the cages. Growth rate was higher in the low algal cover treatment. Understanding the major factors affecting growth and competition of an organism is essential to explaining underlying spatial distributions and developing conservation strategies.