Macrolgae as an indicator of the environmental health of the Pirangi reefs, Rio Grande do Norte, Brazil

Abstract

Abstract:The coral reefs of Pirangi beach have suffered the impact of anthropic actions, mainly those related to tourism. To evaluate these effects, algal samples were collected at nine stations, distributed along the reef fringe. The macrobenthic community (algae/coral) was identified through photographic methods. A total of thirty species of algae, five species of coral, and one species of mollusk were identified. In areas of intense tourist activity, small algae were predominant, while in areas without human interference, foliose algae were predominant. Cluster analysis of the organisms revealed a pattern in spatial distribution into five zones: (1) a submerged zone with very diverse flora, (2) a zone with a predominance of Caulerpa racemosa, (3) a zone with high coverage of Sargassum vulgare, (4) a trampled zone with bare spaces, small algae and Zoanthus sociatus, and (5) a zone with predominance of Palythoa caribaeroum. The results show that human disturbances of the natural order can result in a different distribution model for benthic organisms in reefs. Moreover, these results allow us to infer that the area studied has undergone changes resulting from human activities and that the differences in biological composition can be used as an important indicator of the health of the Pirangi reef.

Historical biogeography of the widespread macroalga Sargassum (Fucales, Phaeophyceae)

“…Thus, phase shift to macroalgal dominance by this ubiquitous reef genus is a serious threat to corals and an indication of poor reef health (Azevedo et al. , Smith et al. ).…”

Recreational Diving and Its Effects on the Macroalgal Communities of the Unintentional Artificial Reef Zenobia Shipwreck (Cyprus)

“…Then for each 50 cm × 50 cm plot, which represents our sampling area, we subsampled four 25 cm × 25 cm sub-plots. In each area a 15 m transect was haphazardly placed and pictures were taken continuously along the transect and replicated three times using the photo-quadrat method [24,50,[57][58][59]. A total of 1080 photos were produced for the analysis.…”

“…Coral Point Count with Excel extensions [60] was used to analyse the macroalgal cover by replacing build-in codes according to our needs. The macroalgal coverage was estimated using 100 points randomly overlaid over each picture, according with literature [50], for a total of 400 random points for each sampling unit. At each point the presence/ absence of macroalgae was assigned, and points positioned above any other substrate were discarded.…”

“…Overall, anthropogenic disturbance can negatively affect distribution, abundance and taxonomic richness of one or more benthic species, remarking differences between areas exposed and not exposed to a particular disturbance source [49]. In addition, there is evidence of the suitability of benthic communities or species as indicators of human impacts [34,50,51] and, in particular, composition and abundance of benthic macroalgae can be considered as indicators of physical disturbance [24,52].…”

Avaliação do impacto do turismo sobre ambiente recifal costeiro inserido em área marinha protegida

“…Dinsdale e Harriott, 2004;McManus e Polsenberg, 2004). Estudos em comunidades bênticas mostram grande potencial das algas em evidenciar efeitos cumulativos de distúrbios nos ecossistemas marinhos (Pinedo et al, 2007;Akcali e Kucuksezgin, 2011;Azevedo et al, 2011;Vasconcelos et al, 2019).…”