Abstract:The worldwide increase in recreational activities and marine tourism is reason for concern due to its impact on reef environments. In order to assess the effect of tourism on the reef area in Maracajaú (Northeast Brazil), a study was conducted based on the presence of different seaweed species. A region of intense tourist activity was chosen, and another where tourism is prohibited. Result comparison used richness (S), biomass, diversity (H), and dominance (D), as well as an analysis of similarity between samples. Both areas exhibited differences in specifi c composition, biomass, diversity, richness and seaweed dominance. The highest values for biomass, richness and diversity were recorded in the tourism-free region, while the greatest dominance rates were found in the area of intense tourist activity. The latter was characterized by the dominant presence of Caulerpa racemosa (Forsskål) J. Agardh (Chlorophyta) and turf algae. These characteristics are a clear indication that the reef area subject to heavy tourist activity is undergoing degradation.
Based on morphological studies, four species of Chondracanthus Kützing were previously reported on the Brazilian coast: C. acicularis (Roth) Fredericq, C. elegans (Greville) Guiry, C. saundersii C.W.Schneider and C.E.Lane and C. teedei (Mertens ex Roth) Fredericq. In the present study, specimens of Chondracanthus were collected from intertidal and subtidal zones (up to 18 m depth); morphological, molecular and phylogenetic analyses were performed using DNA barcoding (cox1) as a tool in a survey of Rhodophyta biodiversity in São Paulo state. Unlike what we expected, C. saundersii is widely distributed, and many specimens were misidentified as C. acicularis or C. teedei before this study, suggesting the necessity of an accurate revision in the previous identifications of the species of Chondracanthus in Brazil. Tetrasporangial and cystocarpic structures of C. saundersii are described for the first time. Our results confirm that the utilization of cox1 sequences as DNA barcode is an efficient tool to complement morphological identification for species of the genus Chondracanthus. Keywords cox1 Á Phylogeny Á rbcL Á Taxonomy Abbreviations cox1 Cytochrome c oxidase GTR General-time-reversible model invariable sites and shape parameter of the gamma distribution MP Maximum parsimony NJ Neighbor-joining PP Posterior probability rbcL Gene coding for the large subunit of RUBISCO Electronic supplementary material The online version of this article (
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