Dinoflagellate community structure under a metacommunity perspective: Assessing the relative importance of local filters and spatial dynamics

Abstract

Metacommunity dynamics, which often underpin species distribution, may provide insights into the mechanisms structuring phytoplankton communities. Contrary to the effects of local filters (e.g., physicochemical parameters), the role of regional scale dispersion on phytoplankton community structure remains far less studied. While most of our knowledge on dinoflagellate community structure relies on niche-based assumptions, local habitats processes may likewise play a significant structuring role. Our aim is to determine the relative contribution of dispersal and local filters to predict the distribution of dinoflagellates, and how they compose local communities. To this effect, metacommunity theory may serve as a basis to describe community changes and to predict harmful algal blooms. Over four annual campaigns, we sampled several biological and physico-chemical attributes along a salinity gradient of three rivers associated to a tropical estuarine complex, the Camamu Bay (Bahia, Brazil). We conducted variance partitioning and multivariate analysis to detect patterns associated to community composition and distribution and to quantify the importance local filters and space (e.g., dispersal) may have in structuring dinoflagellate metacommunities. While our results indicate that local filters had better explanatory power over the biological variability during the dry seasons, when dispersal processes were included in our analysis, greater explanatory power was achieved. In the entire estuary, salinity acts as the most important variable for structuring dinoflagellates, and its effect remained significant during all the sampling campaigns. The differences between the dry and rainy season campaigns may mostly be understood in term of hydrological regimes (e.g., stratification and runoff), which directly impact the dispersal patterns responsible for structuring dinoflagellate community.