The Role of Reproduction in the Ecology and Life History of Tropical Green Algae

Lewis And Clark College, Portland OR

Investigators

Abstract

Siphonous green algae are a conspicuous feature of many tropical marine habitats, including coral reefs, seagrass beds, and mangroves. Within these communities, green algae typically represent an important source of food, shelter, competition, and sediment. Understanding the factors that govern the timing, intensity, and consequences of algal reproduction represents an important step towards elucidating the ecological role of green algae within tropical marine habitats. This study seeks to examine the environmental factors governing the onset and timing of sexual reproduction; the resulting success of gamete release; and the association between these variables and patterns of algal dispersal, recruitment, and, life?history. Field studies will link the environment and algal ecology, particularly with regard to life history parameters and the expression of sexual reproduction. Using permanent quadrants, the investigator will quantify patterns of algal growth, mortality, and reproduction (both sexual and asexual). Measures of the physical environment (currents, salinity, day length, temperature) and demography (age, size, density) will be correlated with the timing and intensity of reproductive events. Algal transplants will help identify causality among these variables. Zygote dispersal and development will be monitored during early life?history. In addition, the investigator will study fertilization as a function of gamete size and behavior (e.g. motility, phototaxis, etc.) by mixing of gametes, in vitro, at varied concentrations. Spatial and temporal patterns of gamete concentration will be quantified, in situ, as a function of adult dispersion, gamete production, gamete size, and the physical environment. These data will be compared with rates of gamete cloud dispersion by means of video/image analysis.