Assessment of temperature and nutrient gradient on seasonal dynamics of Hypnea musciformis complex (Gigartinales, Rhodophyta) from South Florida

Abstract

Macroalgal assemblages' dynamics respond to natural seasons and spatial heterogenity. However,the increase in temperature, related to global climate change, and increasing urbanization, resulting in high nutrient load are altering diversity and abundance patterns of those assamblages. Hypnea musciformis species complex (Gigartinales, Rhodophyta) is being used as a case study to predict how the impacts of global stressor, such as warming, will affect its distribution on the Brazilian coast. However, little is known about how this algae are responding to local stressors, for example nutrient loading. The coastal bays of South Florida are located downstream of the Florida Everglades, where a comprehensive restoration plan is expected to impact the hydrology of the region. Subaquatic vegetation communities are common components of benthic habitats of this area and are directly affected by changes in water quality. The goal of this case study is to examine the spatio- temporal variability of temperature and nutrient availability impact on the dynamics of Hypnea musciformis complex. This will be done by: (1) evaluating seasonal and spatial patterns of H. musciformis species complex abundance along a nutrient gradient in South Florida; (2) measuring H. musciformis species complex tissue-nutrient content spatial and temporal varibaility and (3) exploring the relationships between H. musciformis species complex taxonomic divergences and water quality parameters (nutrient, salinity and temperature). (AU)