THE STRUCTURE OF SUBTIDAL MACROALGAL ASSEMBLAGES AT THE TAMOIOS ECOLOGICAL STATION, A THREATENED CONSERVATION UNIT IN RIO DE JANEIRO, BRAZIL

É insuficiente a caracterização da estrutura de comunidade de costões rochosos na Estação Ecológica de Tamoios (ESEC Tamoios), Baía da Ilha Grande, estado do Rio de Janeiro, assim como em outras unidades de conservação marinhas do Brasil. No presente estudo, foi descrita a assembleia de macroalgas do infralitoral raso de substrato rochoso em duas ilhas da ESEC Tamoios: Imboassica (IM) e Búzios Pequena (BP), utilizando-se espécie e gênero como unidades observacionais. Em cada ilha, duas localidades foram amostradas no verão de 2011. Quadrados de 30x30 cm (n=3), dispostos aleatoriamente, foram raspados para coletar macroalgas, excetuando-se as incrustantes. As assembleias do infralitoral, onde 58 espécies de macroalgas foram identificadas, foram caracterizadas pela alta frequência e percentagem de cobertura de Sargassum vulgare C. Agardh (56,8±8,4%). As localidades foram significativamente diferentes no número total de espécies e no índice de diversidade Shannon-Weiner (PERMANOVA, p;5%) foram: Sargassum, Laurencia, Wrangelia, Canistrocarpus, Asparagopsis, Hypnea, Ceratodictyon, Gayliella, Spyridia e Chondria. As dissimilaridades encontradas dentro e entre as ilhas, visualizadas por nMDS para dados de cobertura, apontam a necessidade de considerar diferentes escalas espaciais para o monitoramento das comunidades de costões rochosos da Baía da Ilha Grande.The structure of subtidal rocky bottom communities at Tamoios Ecological Station (TES), situated in Ilha Grande Bay, Rio de Janeiro State, as well as in other Brazilian marine protected areas, is insufficiently characterized. The present study describes the macroalgal assemblages of shallow subtidal rocky bottoms on two islands of the TES-Imboassica (IM) and Búzios Pequena (BP)adopting species and genera as observational units. Two sites were surveyed on each island in summer 2011. Random 30x30 cm quadrats (n=3) were scraped to collect all macroalgae except crustose species. The subtidal assemblages, in which 58 macroalgal species occurred, were characterized by the high frequency and percent cover of Sargassum vulgare C. Agardh (56.8±8.4%). The sites differed significantly in total number of species and Shannon-Weiner diversity index (PERMANOVA, p;5%) were Sargassum, Laurencia, Wrangelia, Canistrocarpus, Asparagopsis, Hypnea, Ceratodictyon, Gayliella, Spyridia and Chondria. Dissimilarities within and between the islands, as shown by nMDS of the cover data, suggest that different spatial scales should be considered in monitoring the rocky bottom communities of Ilha Grande Bay

Variação sazonal do epifitismo por macroalgas em uma população de sargassum vulgare c. Agardh (phaeophyceae, fucales) da Baía da Ilha Grande, Rio de Janeiro

SEASONAL VARIATION OF MACROALGAL EPIPHYTISM IN A Sargassum vulgare C. AGARDH (PHAEOPHYCEAE, FUCALES) POPULATION FROM ILHA GRANDE BAY, RIO DE JANEIRO. Epiphytism is an important variable to be considered in studies of marine benthic community structure. The epiphytism of macroalgae enhances stratification in rocky shores, leading to habitat heterogeneity, and increasing species diversity, due to greater diversification of the resources available to the associated fauna. There are records of temporal variations in the number of species and biomass of epiphytic macroalgae, and in some studies these variations were correlated with the degree of vegetative development of the host macroalga. Regarding the populations of Sargassum, the currently available information is insufficient to define relationship patterns between the vegetative development of Sargassum and its epiphytes. The present study aimed: 1) to describe seasonal variations in qualitative and quantitative aspects of the epiphytic macroalgae of a Sargassum vulgare population from the region of Angra dos Reis, Ilha Grande Bay, Rio de Janeiro State, Brazil; and 2) to assess the relationship between degree of epiphytism and vegetative development of the host macroalga. Twenty S. vulgare adult plants were randomly sampled from Gordas Beach in February, May, July and October 2001. Any epiphytic macroalga placed on their thalli were extracted, sorted, identified, classified into morphofunctiontal types, dehydrated and weighted. Apart from calcareous crusts, 46 species of macroalgae (27 Rhodophyta, eight Ochrophyta, and 11 Chlorophyta) were identified. The most numerous groups found were of the order Ceramiales (14 species) and of the filamentous morphofunctional type (17 species). Jania adhaerens and Jania capillacea were the most frequently found epiphytic species in this study. The mean number of species of epiphytic macroalgae found on each Sargassum individual was 7.6. The greatest biomass of epiphytic macroalgae was found during summer, coinciding with the greatest height and wet mass values of S. vulgare. However, we detected no linear relationship between these variables. Keywords: Community structure, epiphytes, Ilha Grande Bay, macroalgae, rocky shores, Sargassum, seasonality.O epifitismo é uma variável importante no estudo da estrutura das comunidades marinhas bentônicas. Em costões rochosos, o epifitismo por macroalgas resulta em maior número de estratos, heterogeneidade de habitats e diversidade específica, constituindo recursos diversos para a fauna associada. Variações temporais no número de espécies e na biomassa de macroalgas epífitas são descritas na literatura, sendo relacionadas, em alguns estudos, ao grau de desenvolvimento das macroalgas-substrato. Para a macroalga-substrato Sargassum, os estudos existentes não são suficientes para definir um padrão de relação entre o seu desenvolvimento vegetativo e o de suas epífitas. Este trabalho teve por objetivos descrever a variação sazonal em aspectos qualitativos e quantitativos de macroalgas epífitas em Sargassum vulgare de uma população de Angra dos Reis, Baía da Ilha Grande, Rio de Janeiro, e avaliar a relação do grau de epifitismo com o desenvolvimento vegetativo da macroalga-substrato. Coletas aleatórias de 20 indivíduos adultos de S. vulgare da praia das Gordas, Angra dos Reis, foram realizadas em fevereiro, maio, julho e outubro de 2001. As macroalgas epífitas, excetuando-se as calcárias crostosas, foram separadas por tipo morfofuncional, secas em estufa e pesadas. Foram identificadas 46 espécies de macroalgas (27 Rhodophyta, oito Ochrophyta e 11 Chlorophyta). Ceramiales (14 espécies) e tipo morfofuncional filamentoso (17 espécies) foram os grupos mais representativos em termos de número de espécies epífitas. O número de espécies de macroalgas epífitas por indivíduo de S. vulgare foi 7,6, em média. Jania adhaerens e J. capillacea foram as epífitas mais freqüentes ao longo do estudo. No verão, foram encontrados os maiores valores para massa seca de macroalgas epífitas, bem como para altura e massa úmida de S. vulgare; estas variáveis, no entanto, não mostraram relação linear entre si. Palavras-chave: Baía da Ilha Grande, costão rochoso, epífitas, estrutura de comunidades, macroalgas, Sargassum, sazonalidade

Natural and anthropogenic factors as possible drivers of variability in rocky shore assemblages at multiple spatial scales

Spatial and temporal variability in rocky shore assemblages at multiple scales can be driven by natural factors and anthropogenic disturbances, operating either separately to each other or in complex combinations. Using the shallow subtidal rocky habitat in Ilha Grande Bay (southeastern Brazil) as a model system, this study analyzed five natural and five anthropogenic variables as possible drivers of variability of cover in rocky shore assemblages, focusing on the following questions: (i) Which are the relevant horizontal scales of variation in assemblage structure?; (ii) Are patterns of horizontal variation consistent across a small depth range?; (iii) Are there significant relationships between spatial patterns of macroalgae and macroinvertebrates, and their potential natural and anthropogenic drivers? These issues were addressed through a hierarchical sampling strategy including five horizontal scales, namely quadrat (0.4–3 m), point (3–10 m), site (100–350 m), island (500–1000 m) and area (2000–6500 m), repeated at two depths (1–2 m and 3.5–4.5 m). The correlations of cover data of 21 groups of organisms and five natural and five anthropogenic variables were analyzed. Assemblages showed relevant variation among quadrats, points and sites, at both depths, while variation at the area scale was relevant only at 3.5–4.5 m depth, indicating that patterns of horizontal variation were not fully consistent between depths. Substrate rugosity, rocky shore extension, water movement, percentage of deforested land area and distance to urban center were the environmental variables that most explained spatial patterns of the assemblages. Our study highlights the potential role of such variables as drivers of variation in rocky subtidal assemblages at multiple spatial scales. For environmental protection programs, relevant scales of variation of target populations and assemblages need to be considered, to effectively capture their dynamics and underlying processes

Reconciling vertical and horizontal variability in Sargassum populations for improved environmental monitoring

The genus Sargassum C. Agardh (Phaeophyceae) and other fucoids are important focuses of worldwide research owing to their ecological role and value as indicators of environmental quality. Sargassum species are among the most common habitat-forming macroalgae in shallow subtidal rocky habitats along the Brazilian coast. Understanding patterns of variation in Sargassum populations at multiple scales is essential to determine monitoring designs. The aim of this study was to answer three main questions, using Ilha Grande Bay as a case study: (1) Which are the relevant scales of horizontal variability in cover and density of Sargassum populations? (2) Are horizontal patterns consistent across depth?, and (3) Should small depth differences be included in monitoring designs for shallow Sargassum populations? These issues were addressed through a sampling program including five horizontal scales: area (2000–6500 m apart), island (500–1000 m apart), site (100–350 m apart), point (3–10 m apart), and quadrat (0.4–3 m apart). The same approach was repeated at two depths (1.0–2.0 m and 3.5–4.5 m). Quadrat, point, and site were identified as relevant scales of variability for all variables, although patterns of horizontal variability were not consistent through depth. These findings suggest that both small-scale vertical and small to intermediate-scale horizontal variations (up to 10 m and ~ 300 m, respectively) should be included in monitoring programs of Sargassum populations. Ultimately, this has technical and economic implications for management and conservation initiatives focused on such important habitat formers

Levantamento florístico das macroalgas da baía de Sepetiba e adjacências, RJ: ponto de partida para o Programa GloBallast no Brasil Floristic survey of the macroalgae from Sepetiba bay and surrounding area, Rio de Janeiro State: starting point for the GloBallast Programme in Brazil

O Porto de Sepetiba, Estado do Rio de Janeiro, foi escolhido, no Brasil, como área-piloto do projeto "Remoção de barreiras para a implementação efetiva do controle de água de lastro e medidas de gestão em países em desenvolvimento" (Programa GloBallast). Para possibilitar comparações, os seis países participantes do Programa GloBallast foram orientados a adotar a mesma metodologia para o levantamento preliminar da biota das áreas-pilotos valorizando a identificação em nível de espécie. O presente estudo teve como objetivo aplicar metodologia estabelecida pelo Centro para Pesquisa sobre Espécies Marinhas Introduzidas, da Austrália (Procedimento CRIMP), com algumas adaptações, no levantamento florístico das macroalgas de substratos consolidados naturais da área-piloto do Porto de Sepetiba. Coletas de macroalgas foram realizadas em novembro/2001, em nove locais da baía de Sepetiba e adjacências, desde a franja da região sublitorânea até cerca de -4 m de profundidade. Em cada local, seis quadrados de 0,1 m² de área foram raspados. O material foi depositado no Herbário do Instituto de Pesquisas Jardim Botânico do Rio de Janeiro (RB). Das 96 espécies identificadas (20 Chlorophyta, 16 Phaeophyta, 60 Rhodophyta), 12 não haviam sido citadas anteriormente para a área de estudo. Cladophora pellucidoidea C. Hoek, Coelothrix irregularis (Harv.) Boergesen e Acrochaetium savianum (Menegh.) Nägeli são ocorrências novas para o Estado. Não há indícios de que as novas ocorrências equivalem a espécies recentemente introduzidas por meio das atividades portuárias. O procedimento metodológico adotado mostrou-se eficiente, resultando em listagem de espécies comparável às de levantamentos florísticos com maior esforço amostral e complementando os dados pretéritos existentes para a baía de Sepetiba e adjacências. No entanto, ressalta-se a importância de uma reavaliação das escalas temporal e espacial da estratégia de amostragem, em estudos futuros. Recomenda-se a padronização metodológica para o levantamento florístico de áreas portuárias como a baía de Sepetiba, e de outras áreas do litoral brasileiro sujeitas à interferência do homem, tomando por base o procedimento CRIMP.The Port of Sepetiba, State of Rio de Janeiro, was chosen as the Brazilian pilot area for the project "Global Ballast Water Management Programme" (GloBallast Programme). For comparative purposes, six countries were guided by the GloBallast Programme to follow the same methodology, emphasizing identification of organisms to the specific level during the preliminary biota survey. This study aimed to apply the methodology established by the Australian Centre for Research on Introduced Marine Pests (CRIMP procedures) for the floristic survey of macroalgae of natural hard substrate of the area of Port of Sepetiba. Macroalgal samplings were carried out in November 2001 at nine sites situated in Sepetiba Bay and adjacent area, from the sublittoral fringe to ca. - 4 m deep. At each site, six 0.1 m² quadrates were scraped. Specimens were sent to the Herbarium of the "Instituto de Pesquisas Jardim Botânico do Rio de Janeiro" (RB). Ninety six species were identified (20 Chlorophyta, 16 Phaeophyta, and 60 Rhodophyta); 12 species have not been cited to the study area by the preceding studies. Cladophora pellucidoidea C. Hoek, Coelothrix irregularis (Harv.) Boergesen, and Acrochaetium savianum (Menegh.) Nägeli are recorded for the first time to the state of Rio de Janeiro. There are no evidences to conclude that the new records correspond to recently introduced species through the port activities. The methodological procedures proved to be efficient because they produced a species list to be comparable to those of taxonomic surveys with higher sampling effort. They also enlarged the existing information about the phycological flora of Sepetiba Bay. Nevertheless, for future studies, we point out the importance of a re-evaluation of the temporal and spatial scales of the sampling strategy. We recommend the methodological standardization of floristic surveys for port areas such as Sepetiba Bay, as well as other Brazilian coastal areas subjected to human interferences, taking into account the CRIMP procedures