Analysis of marine diversity and anthropogenic pressures on Seixas coral reef ecosystem (northeastern Brazil).

Coral reefs, vital and ecologically significant ecosystems, are among the most jeopardized marine environments in the Atlantic Ocean, particularly along the northeastern coast of Brazil. The persistent lack of effective management and conservation has led to fragmented information on reef use and pressures, hindering the understanding of these ecosystems' health. Major difficulties and challenges include inadequate data, diverse anthropogenic pressures, and the complex interaction between marine species. This study sought to bridge this knowledge gap by conducting a comprehensive analysis of marine diversity and anthropogenic pressures, specifically focusing on Seixas coral reef near João Pessoa city, an area notably impacted by tourism. Utilizing 25 monitoring transects, subdivided into 1 m2 quadrants, the marine diversity was meticulously evaluated through innovative procedures including (a) sedimentological and geochemical field surveys, (b) application of Shannon-Weaver diversity and Simpson dominance indices, (c) cluster analysis, (d) species identification of macroalgae, coral, and fish, and (e) an examination of anthropogenic interactions and pressures on the coral reef. The assessment encompassed three distinct zones: Back Reef, Reef Top, and Fore Reef, and identified a total of 25 species across 15 genera and 10 fish families. The findings revealed the prevalence of brown macroalgae, fish, and coral, with heightened abundance of red macroalgae in the Fore Reef, which also exhibited the greatest diversity (2.816) and dominance (0.894). Original achievements include the identification of specific spatial variations, recognition of the anthropogenic factors leading to ecological changes, and the formulation of evidence-based recommendations. The study concludes that escalating urbanization and burgeoning daily tourist visits to the reef have exacerbated negative impacts on Seixas coral reef's marine ecosystem. These insights underscore the urgent need for strategic planning and resource management to safeguard the reef's biodiversity and ecological integrity.

An Overview of Rhodoliths: Ecological Importance and Conservation Emergency.

Red calcareous algae create bio-aggregations ecosystems constituted by carbonate calcium, with two main morphotypes: geniculate and non-geniculate structures (rhodoliths may form bio-encrustations on hard substrata or unattached nodules). This study presents a bibliographic review of the order Corallinales (specifically, rhodoliths), highlighting on morphology, ecology, diversity, related organisms, major anthropogenic influences on climate change and current conservation initiatives. These habitats are often widespread geographically and bathymetrically, occurring in the photic zone from the intertidal area to depths of 270 m. Due to its diverse morphology, this group offers a special biogenic environment that is favourable to epiphyte algae and a number of marine invertebrates. They also include holobiont microbiota made up of tiny eukaryotes, bacteria and viruses. The morphology of red calcareous algae and outside environmental conditions are thought to be the key forces regulating faunistic communities in algae reefs. The impacts of climate change, particularly those related to acidification, might substantially jeopardise the survival of the Corallinales. Despite the significance of these ecosystems, there are a number of anthropogenic stresses on them. Since there have been few attempts to conserve them, programs aimed at their conservation and management need to closely monitor their habitats, research the communities they are linked with and assess the effects they have on the environment.

Marine invertebrates associated with rhodoliths/maërl beds from northeast Brazil (State of Paraíba).

BACKGROUND: This study investigates the marine macroinvertebrate fauna of rhodolith beds (non-geniculated red corallinaceaous algae) in northeast Brazilian. A total of 57 species were identified, belonging to six phyla (Platyhelminthes, Annelida, Sipuncula, Mollusca, Arthropoda and Echinodermata), of which 50 are considered here as new records for the Paraíba State. Annelids (Class Polychaeta) were the most representative taxa in Miramar and Seixas Beaches, while molluscs were dominant in Maceió Beach. NEW INFORMATION: This is the first study that includes an identification key, diagnostic features and distribution patterns worldwide and local (including new records) of the marine invertebrate fauna associated with rhodolith beds in northeast Brazil (State of Paraíba). Sampling events were performed in 2018, at low tide in the intertidal to shallow subtidal zones (1.5 and 4.0 m depth), in Miramar, Seixas and Maceió Beaches. A total of 17 species were found for the first time on Seixas Beach, as well as all identified species for Miramar and Maceió. This study tries to contribute to the knowledge of marine invertebrates in northeast Brazilian shallow habitats, providing a baseline for future environmental studies.

Is tourism affecting polychaete assemblages associated with rhodolith beds in Northeastern Brazil?

Introduction: Rhodoliths are biogenic structures distributed worldwide, formed by several types of calcareous algae. They may host a great diversity of marine invertebrates, among which polychaetes are conspicuous and diversified representatives. Rhodolith beds are notwithstanding vulnerable to several human activities (e.g. exploitation of commercial species associated with rhodoliths, petroleum exploration, fishing activities, effluent discharges, and tourism), which may compromise that diversity. Tourism is presently increasing its impact on rhodolith beds. Global warming and ocean acidification are also determinant factors in faunal change. Objective: to analyse the polychaete assemblages associated with rhodolith beds subject to different intensities of touristic pressure at Seixas Beach (NE Brazil), where tourism is gradually increasing over time. Methods: Effects were evaluated at two depths, 1.5 m and 4.0 m. Sampling was done every two months during 2015, encompassing the two marked seasons of the year in the region (rainy and dry). Quadrats of 15 x 15 cm were placed in each depth during sampling. All rhodoliths present within the quadrat were collected (usually four to five rhodoliths). Our hypothesis was that the deeper depth and the samples from the dry season months would be increasingly subject to the impact of tourism. Results: Overall, 49 species were found (from 21 different families), and a total of 733 individuals were collected. The most abundant species was Eunice wasinensis (280 individuals, 38.2% of total abundance). The species Eurythoe complanata, Eunice biannulata, E. wasinensis, Lysidice ninetta, Oxydromus pugettensis and Ceratonereis (Ceratonereis) singularis appeared in all months. The study detected a tendency for higher diversity to occur at the depth of 1.5 m for all indices, but only the Shannon-Wiener values were significantly higher there (p < 0.05). No clear differences were found regarding months or season. Conclusions: These results suggest that a higher potential pressure due to tourism may occur at 4.0 m due to more intense craft shipping activities (traffic of catamaran boats transporting tourists to and from the reefs) in that area.

Introducción: Rodolitos son estructuras biogénicas distribuidas en todo el mundo, formadas por varios tipos de algas calcáreas. Pueden albergar una gran diversidad de invertebrados marinos, entre los cuales los poliquetas son representantes conspicuos y diversificados. No obstante, los fondos de los rodolitos son vulnerables a varias actividades humanas (por ejemplo, la explotación de especies comerciales asociadas con rodolitos, exploración petrolera, actividades de pesca, descargas de efluentes y turismo), que pueden comprometer esa diversidad. El turismo está aumentando su impacto en los fondos de rodolitos. El calentamiento global y la acidificación de los océanos también son factores determinantes en el cambio de fauna. Objetivo: El presente estudio tuvo como objetivo analizar los conjuntos de poliquetos asociados con fondos de rodolitos sujetos a diferentes intensidades de presión turística en la playa de Seixas (Nordeste de Brasil), donde el turismo está aumentando gradualmente con el tiempo. Métodos: Los efectos fueron evaluados a dos profundidades, 1.5 m y 4.0 m. El muestreo se realizó cada dos meses durante 2015, abarcando las dos estaciones marcadas del año en la región (lluviosa y seca). Se colocaron cuadrantes de 15 x 15 cm en cada profundidad durante el muestreo. Se recolectaron todos los rodolitos presentes dentro del cuadrante (generalmente de four a five rodolitos). Nuestra hipótesis era que la mayor profundidad y las muestras de la estación seca estarían cada vez más sujetas al impacto del turismo. Resultados: En total, se encontraron 49 especies (de 21 familias diferentes) y se recolectó un total de 733 individuos. La especie más abundante fue Eunice wasinensis (280 individuos, 38.2 % de la abundancia total). La especie Eurythoe complanata, Eunice biannulata, E. wasinensis, Lysidice ninetta, Oxydromus pugettensis y Ceratonereis (Ceratonereis) singularis aparecieron en todos los meses. El estudio detectó una tendencia a mayor diversidad en la profundidad de 1,5 m para todos los índices, pero solo los valores de Shannon-Wiener fueron significativamente mayores allí (p < 0.05). No se encontraron diferencias con respecto a los meses. Conclusiones: Estos resultados sugieren que puede haber una mayor presión potencial debido al turismo a 4.0 m debido a actividades de embarcaciones más intensas (tráfico de catamaranes que transportan turistas hacia y desde los arrecifes) en esa área. Nuestros resultados aumentan nuestro conocimiento sobre la diversidad de poliquetos asociados con los fondos de rodolitos en áreas tropicales, y resaltan la necesidad de estudios de monitoreo para probar el impacto de los factores de estrés locales en estos conjuntos.