Macroalgal taxocoenosis as indicators of water quality in coastal systems

Abstract

Background: Macroalgae communities predominate in coastal areas, especially on rocky shores. The species composition of such communities may be characteristic of a quality status of water inasmuch each species either adapt or not to the physicochemical variables (temperature, pH, salinity and dissolved oxygen). Therefore, differences in species composition would be expected from different concentrations of diluted compounds in water. Goals: To determine the macroalgae’s tolerance intervals to physicochemical conditions, and to classify them as tolerant if they survive within wide intervals, or as sensitive, poorly tolerant species that are distributed under restricted water conditions. Methods: A database was built of georeferenced records of other localities on the planet where species present on the coast of Baja California Sur are also found, was obtained from the Global Biodiversity Information Facility (GBIF). Besides, the 2005 to 2012 average values for physicochemical variables and the concentration of nutrients in the water (nitrate, phosphate, silicate and dissolved organic matter) were gathered from other places where each specie has been recorded through satellite images obtained by remote sensors of the National Oceanic and Atmospheric Administration (NOAA). Results: A heatmap was generated showing an apparent distinction in the floristic composition (taxocoenosis), facing possible change scenarios which proposes to include the species that survive within wide physicochemical and/or nutrient variations as part of the reference for protocols on the distribution of mineral content. While species with narrow intervals of occurrence in the measured variables should be considered as taxa that indicate the intervals at which they occur. Conclusions. Possible taxocoenosis that can occur in BCS under different water quality conditions are here proposed. These depend mainly on the concentration of nutrients (silicate and organic matter) and physicochemical (dissolved oxygen and pH) as being those variables with a greater influence on the species association for a given quality status.