Diatomáceas epífitas em macroalgas marinhas do nordeste do Brasil

Abstract

Epiphytic diatoms play an important role in coastal ecosystems; it has believed to contribute to approximately 40% of the oceanic primary production. Are microalgae that have developed several strategies for attachment to the host, including the ability to secrete mucilaginous substances, which form short or long stems. According to the form of accession, diatoms can be classified as erect (fixed to the host through mucilaginous stalks), motile (sliding in the host's surface) and adnate (largest adhesive to the host directly by valves). The form of accession or type of growth of diatoms can connected to the architectural differences species of seaweeds, conditioning changes in structure of the epiphytic community between hosts with different types of stems or between the same species inhabiting areas with different environmental characteristics. The objective of this study was to identify the structure and qualitative and quantitative variations of epiphytic diatom community in seaweeds from the northeastern coastal Brazil. In this context, the present study was intended to proved the following hypotheses: 1) The community of diatoms epiphytic presents qualitative and quantitative differences and as adhesion between macroalgae with different architectures stems; 2) There are significant differences in populations of diatoms epiphytes in different parts of the stem of the same host; 3) The diatoms epiphytic flora of quantitative variations in the thalli presents the same even when the host dwelling places with different environmental characteristics. The research resulted in the development of three manuscript. In the first, an assessment was made of the epiphytic diatoms adhesive strategies in three species of seaweeds collected in the subtidal zone of Pernambuco: Bachelotia antillarum (Phaeophyceae), Caulerpa verticillata (Ulvophyceae) and Haloplegma duperreyi (Rhodophyceae), concluding that the differences between the growth forms of agreements are assigned to morphological differences of the three species of seaweeds. The second manuscript addressed the variability and the vertical distribution of diatom species associated in each part of the stem of three species of seaweed (apical, mean and basal) were collected from intertidal of Alagoas: Codium isthmocladum (Ulvophyceae), Spatoglossum schroederi (Phaeophyceae) and Hidropuntia cornea (Rhodophyceae), concluding that significant variations occur between different parts of the thallus, with greater richness and abundance in the apical part of the rhodophyte Hidropuntia cornea. The third paper analyzed the qualitative and quantitative variation of the epiphytic flora in rhodophyte Galaxaura rugosa (J. Ellis & Solander) J.V. Lamouroux collected in the island region, subject to variation in environmental conditions, noting that the greatest richness of diatoms occurs when the host dwelling places with less influence of winds and ocean currents, while the lowest wealth occurs when the host dwelling places subject to greater movement of marine currents.