Modern spatial distribution of dinoflagellates and non- palynomorfis in a neotropical estuary (Northeastern Brazil).

Abstract

Increasing temperatures as a consequence of the global climate changes has been considered as a central topic for many sciences. In local scales, the consequences of the anthropogenic pressure against the environment also affect and alter the composition and distribution of biological communities. The dynamics of such communities are also mechanisms of nutrient regulation and cycling within the basis of the trophic complex. The composition of phytoplanktonic communities relies also on bloom-forming species, leading to consequences for the ecosystem balance and human health, given the ability of some species to produce toxins that may be transferred through the food web. Hence, we aim to use the spatial dynamics of the palynomorph assemblages to understand ecological aspects, such as the succession dynamics and the environmental characteristics affecting their composition and distribution. The present thesis is composed of an introductory chapter, a chapter describing a planktonic foam-plume bloom of co-occurring toxin-producing dinoflagellates; another chapter describing the unusual benthic high concentration of the same species complex within surface sediments of an urbanized area, where there are fishing and shellfish consumption; another chapter modelling the local distribution of non-pollen palynomorphs alongside the estuarine gradients; and finally a conclusion chapter reuniting and bonding the informations. The combined bloom of Prorocentrum lima and Prorocentrum rhathymum in the magnitude of millions of cells per litre represents a novelty for the South and Central Atlantic, where these species are abundantly distributed. The occurrence of P. lima in sand substrate after palynological treatment is also a novelty. The distribution of green algae and cyanobacteria in sites with decreased salinity and increased light and nutrient availability, as well as the distribution of the marine members in sites with higher salinity corroborates the local response of the assemblage to the characteristics of the estuarine environment. The dominance change from green algae in the modern assemblage to cyanobacteria and fungal spores in the fossil assemblage suggests potential environmental variations related to human occupation. The response of these organisms represents a relevant contribution in the actual scenario of global climate changes, since the role these organisms play in local and large scale biogeochemical processes.