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While marine protected areas (MPAs) are increasing worldwide, it is still needed to assess the effectiveness of those already consolidated. Methods and ecological assessments to understanding integrated and habitat-specific management regimes are still scarce and insufficient for policy implications and biodiversity conservation. Through Baited Remote Underwater Video (BRUV), we used fish assemblages as proxy of ecological and managerial status in two reef habitat types along three protection levels at Abrolhos Bank - the largest and most biodiverse coral reef complex of the South Atlantic. We found completely distinct responses in the fish fauna between the top (shallow) and bottom (deep) habitats of the unique "chapeirões" pinnacle reef formations. In the most protected zone (no-take), higher richness and abundance of commercial fish and more diverse trophic structure was observed. Particularly, large (sharks and groupers) and small carnivores (snappers) were more abundant and distributed more homogeneously over both reef habitats in the strictly enforced no-take zone. Abundance of these top-predators decreased from the low enforcement no-take zone to the multiple use area, where they were often absent while their typical preys (primary and secondary consumers) were thriving, notably in the top habitats. These outcomes highlight the importance to focus investigations not selectively on a single habitat type or depth zone in order to properly assess MPA effectiveness. Consequently, the monitoring and protection of fish species supported by marine spatial planning may benefit from an improved understanding of ecological functioning provided by MPA performance.

Understanding how microbial communities are structured in coral holobionts is important to estimate local and global impacts and provide efficient environment management strategies. Several studies investigated the relationship between corals and their microbial communities, including the environmental drivers of shifts in this relationship, associated with diseases and coral cover loss. However, these studies are often geographically or taxonomically restricted and usually focused on the most abundant microbial groups, neglecting the rare biosphere, including archaea in the group DPANN and the recently discovered bacterial members of the candidate phyla radiation (CPR). Although it is known that rare microbes can play essential roles in several environments, we still lack understanding about which taxa comprise the rare biosphere of corals' microbiome. Here, we investigated the host-related and technical factors influencing coral microbial community structure and the importance of CPR and DPANN in this context by analyzing more than a hundred coral metagenomes from independent studies worldwide. We show that coral genera are the main biotic factor shaping coral microbial communities. We also detected several CPR and DPANN phyla comprising corals' rare biosphere for the first time and showed that they significantly contribute to shaping coral microbial communities.

We describe the first record of a whale shark, Rhincodon typus, feeding in Brazilian coastal waters, and the first stranding record in the state of Bahia, Northeast Brazil. In April 2008, an individual of R. typus was observed surface feeding on Dromiidae crab larvae in the continental shelf off the coast of Bahia, near a gas platform. Other fishes were observed foraging in association with the whale shark. We also document the first stranding of R. typus on the coast of Bahia in October 2013. Biometric data confirmed that the stranded whale shark was a juvenile. Stomach content analysis revealed the ingestion of Geryonidae crab larvae. Plastic debris were also found in the gastric lumen of the stranded juvenile whale shark, and we speculate that it could have been a contributing factor to the stranding, and subsequent death of the whale shark. Crab larvae were observed in both of our records and likely to consist as relevant prey items for R. typus in Brazilian continental shelf. Our study provided a contribution on the diet and feeding behaviour of whale sharks in tropical oligotrophic waters and highlights the risks of marine pollution for the species conservation.

Generally, environments with a great habitat complexity (HC) can support a great number of species and large abundances of organisms. However, the mechanisms behind this effect are not entirely clear and some studies did not observe positive effects of complexity on diversity and abundance of biological assemblages. Here, HC was considered as an integrative perspective, specifically as different characteristics of physical structure and; it was tested whether abundance and diversity of macrobenthic assemblages of soft bottom are influenced by variation of two characteristics of habitat complexity, the number and evenness of sediment fractions. The hypothesized positive relationships between HC and richness, Shannon-Wiener diversity index and abundance of benthic macrofauna were not observed. The different response variables (richness, Shannon-Wiener, abundance) which consider different dimensions of biodiversity, can show distinct results when the same habitat is compared. For both structural characteristics of the sediment, a large amount of specimens of Bispira sp. (Polychaeta: Sabellidae) and Terebellides sp. (Polychaeta: Trichobranchidae) were observed in the most complex treatments. These taxa were favored by the presence of gravels where their larvae, likely originated from adult populations at nearby habitats, can settle. The multidimensional structure of the benthic macrofauna was significantly influenced by habitat complexity; and considering high taxonomical and functional diversity, multivariate analyses were more appropriated to investigate such complex effects. In this context, it is clear that careful thought must be given to choose appropriated habitat complexity characteristics and biological measurements. Therefore, studies addressing different combinations of structural characteristics of habitat and mechanisms behind the effects on biological communities are still of great need in ecological science.

Contains fulltext : 218139.pdf (Publisher’s version ) (Open Access) Studies in microbiology have long been mostly restricted to small spatial scales. However, recent technological advances, such as new sequencing methodologies, have ushered an era of large-scale sequencing of environmental DNA data from multiple biomes worldwide. These global datasets can now be used to explore long standing questions of microbial ecology. New methodological approaches and concepts are being developed to study such large-scale patterns in microbial communities, resulting in new perspectives that represent a significant advances for both microbiology and macroecology. Here, we identify and review important conceptual, computational, and methodological challenges and opportunities in microbial macroecology. Specifically, we discuss the challenges of handling and analyzing large amounts of microbiome data to understand taxa distribution and co-occurrence patterns. We also discuss approaches for modeling microbial communities based on environmental data, including information on biological interactions to make full use of available Big Data. Finally, we summarize the methods presented in a general approach aimed to aid microbiologists in addressing fundamental questions in microbial macroecology, including classical propositions (such as "everything is everywhere, but the environment selects") as well as applied ecological problems, such as those posed by human induced global environmental changes.

Overfishing is considered one of the main threats to the health of global marine fish populations. Elasmobranchs that are characterized by low reproductive outputs may be particularly sensitive to intense fishing pressures. The sawfishes stand out as a highly threatened group, due in part to their life history in shallow coastal waters and their ease of capture. In Brazil, sawfish populations are now virtually extinct and these declines have gone undocumented, leaving their precise causes and timing poorly understood. Here, based on ecological and fisheries knowledge of local fishers, we document the disappearance of largetooth sawfish Pristis pristis from 5 estuaries on the central Brazilian coast. Fisher knowledge, combined with an estuarine morphology perspective, revealed important insights on this species, along with a timeline of its decline. Furthermore, fishers’ accounts of the protracted decline revealed clear inter-estuary differences in the timing of population declines, potentially influenced by local geomorphological features. The onset of sawfish population decline appears to have been earlier in estuaries with a direct connection to the sea than in estuaries connected to an inner bay, occurring in the former case from the 1930s onward. A second wave of intensifying decline began in the 1970s in more structurally complex estuaries. Pressures from artisanal and modern fishery practices appear to have led to an earlier population decline in structurally less complex estuaries, while in larger and more complex ones this decline occurred decades later. The replacement of traditional by more modern fishing practices may have triggered the initial phase of local sawfish extinctions.

Sediment load can influence both the population distribution and structures of coral reef communities. We investigated whether coral assemblages on inshore and more turbid reefs differ from those on offshore reefs in the largest coral reefs of the Southwest Atlantic. We compared inshore and offshore reefs (with different turbidity climatologies) in terms of benthic and coral assemblage structures, abundances and individual sizes of coral populations and recruitment patterns. Unexpectedly, the inshore reefs showed higher coral cover and abundance, larger colonies and more recruits. This finding is related to the predominance of sediment-tolerant species on the turbid reefs. In contrast, only Mussismilia braziliensis (main builder of Abrolhos) showed better performance (greater coverage, larger diameter and more recruits) on offshore reefs, apparently behaving as a strong competitor in less turbid environments. These results reinforce the recent thinking of coral reef of turbid environments as resistant ecosystems and potential refuges considering the unnatural increase of sediment supply.

The common dolphinfish (Coryphaena hippurus) is widely distributed and represents an important part of the currently exploited fishery resources. This species’ feeding behaviour, however, is poorly understood. This study aimed to investigate the feeding behaviour of dolphinfish and the effect of body size (and the consequently aggregated learning experience) on the strategies used for capturing their prey. Observations were made from an oil platform in north-eastern Brazil. Dolphinfish length was visually estimated and classified into three size classes. The following foraging strategies were observed in our study: ‘active chasing’, ‘leaping out’, ‘swimming in circles’, ‘surf’, ‘using floating objects’ and ‘cleaning turtle carapaces’. The most frequently used foraging strategy was ‘active chasing’, suggesting a strong preference of dolphinfish in using visual cues during predation. Smaller size-classes of dolphinfish did not perform the ‘swimming in circles’ and ‘surf’ strategy, probably due to a lack of learning experience, since further social interactions could be needed in order to show this strategy. Smaller dolphinfish regularly showed the ‘using floating objects’ as a foraging strategy, probably reflecting an opportunistic behaviour. The smallest individuals were using more simple strategies, to chase smaller prey that could have different and less complex escape strategies. It indicates learning experience could play an important role into the dolphinfish ontogeny, moving towards more complex foraging strategies throughout their lives. Independently of the age class, the dolphinfish displayed a varied repertory of foraging strategies, maximizing hunting success in the open ocean, a hostile pelagic environment with a low prey availability.

Coral reef integrity is currently threatened by natural and human activities. The reefs of the eastern Brazilian coast, which stand out as the largest and richest of the South Atlantic Ocean, are not an exception. Tourism exploitation, destructive fishing practices, increased pollution and uncontrolled coastal development are the major human impacts on reefs. The creation of new no-taken zones (NTZs) has thus become an urgent issue because NTZs represent the best measure to guarantee the conservation of reef ecosystems, which are considered biodiversity hotspots. The objective of this work was to define priority areas for implementing NTZs in a coastal reef complex located on the eastern Brazilian coast (southern coast of Bahia State, in the Tinharé Archipelago), which is within an environmental protection area (Tinharé and Boipeba Islands State Environmental Protection Area [‘Área de Proteção Ambiental Estadual das Ilhas de Tinharé e Boipeba’]). Here we performed a detailed ecological survey of the benthic community in a set of coastal reefs and calculated quantitative conservation priority indices (CPIs) based on ecological attributes associated with the cover of key benthic organisms (corals, macroalgae, filamentous algae, branching and encrusting calcareous algae, sponges and zoanthids) and quantitative indices related to coral species richness and the mean age of the reefs in question. Five coral reefs were classified as high priority for conservation. The large spatial extent of the adjacent fringing reefs of the islands of Tinharé and Boipeba justifies the creation of two rectangular NTZs. We recommend therefore the implementation of two 12 km2 areas spanning two reefs considered of high conservation priority located on the island of Tinharé (“Boca da Barra Norte and Sul”) and one reef located on the island of Boipeba (“Ponta dos Castelhanos”). With this design, two of the reefs that were classified as high priority for conservation, “Piscinas de Moreré” and “Tassimirim” (Boipeba), which are extensively used by local populations (for fishing and tourism), would not be covered by the NTZs. The effectiveness of the conservation of these ecosystems also depends on popular acceptance and participation and on combating destructive anthropogenic activities in the region, which include destructive fishing practices and exploratory tourism. Atualmente a integridade dos recifes de corais está ameaçada por conta de impactos naturais e humanos. Os recifes da costa leste brasileira, que se destacam como os maiores e mais ricos do Oceano Atlântico Sul, não fogem a esta regra. A exploração turística, as práticas de pesca predatória, o aumento da poluição e o desenvolvimento costeiro desordenado representam os principais impactos humanos sobre os recifes. Por conta disso a criação de novas áreas de exclusão de uso (AEUs) se tornaram demandas urgentes e representam a melhor medida para que a conservação desses ecossistemas, considerados como ‘hotspots’ de biodiversidade, seja garantida. A partir disso o objetivo deste trabalho foi definir áreas prioritárias para a implantação de AEUs em um complexo de recifes costeiros localizado na costa leste brasileira (mais especificamente no litoral sul do estado da Bahia, no Arquipélago de Tinharé), os quais estão dentro dos limites de uma área de proteção ambiental (APA estadual das ilhas de Tinharé e Boipeba). Para tanto, aqui nós realizamos um levantamento ecológico detalhado da comunidade bentônica de um conjunto de recifes costeiros e calculamos para cada um destes índices quantitativos de prioridade de conservação (IPC), baseados em atributos ecológicos associados à cobertura de organismos bentônicos chaves (corais, macroalgas, algas filamentosas, algas calcárias ramificadas e incrustantes, esponjas e zoantídeos), e também em índices quantitativos relacionados à riqueza de espécies de corais e à idade média dos recifes em questão. De acordo com o IPC, cinco recifes foram classificados como recifes de alta prioridade de conservação. A grande extensão territorial da franja recifal adjacente às ilhas de Tinharé e Boipeba justifica a criação de duas AEUs com formato retangular (formato mais eficiente para esse tipo de unidade de conservação, segundo a literatura especializada). Sugerimos a implantação de duas áreas com 12 km2, abrangendo dois recifes considerados como de alta prioridade de conservação localizados na ilha de Tinharé (Boca da Barra Norte e Sul) e um recife localizado na ilha de Boipeba (Ponta dos Castelhanos). A partir desse arranjo, dois dos recifes classificados como de alta prioridade para conservação, respectivamente Piscina de Moreré e Tassimirim (ambos localizados na ilha de Boipeba), extensivamente usados pelas populações locais (exploração pesqueira e uso turístico), não seriam contemplados pelas AEUs. Ressaltamos que a efetividade da conservação desses ecossistemas depende, também, da aceitação e participação popular e do combate às ações antropogênicas destrutivas, relacionadas na região às práticas de pesca destrutiva e turismo exploratório.

Fishing pressure affects the behavior of reef fish, especially of fishery-targeted species. In this context, it is critical to understand if fish behavior is preserved in no-take areas (NTAs), which are considered the best instrument for the recovery of fish stocks. Comparing the flight initiation distances (FIDs) of fish inhabiting multiple-use areas (MUAs), where fishing is allowed (including spearfishing), and NTAs is a useful approach to test whether NTAs can be effective as fish refuges. Here, we compared whether the FIDs of two target (Sparisoma axillare and Scarus trispinosus ) and one non-target (Halichoeres poeyi ) labrids are greater in the MUAs than in the NTAs. We also investigated whether group size (GS) and body size (BS) exert any effect on the FID. We sampled four MUAs and four NTAs in the Abrolhos Bank (Brazil). We found that only for the targeted species FID was shorter inside the NTAs and that the BS had a positive effect on the FID of all species. The GS and BS of the fish are greater in the NTAs than in the multiple-use areas only for S. trispinosus . Our study shows that fish, especially those species that are fishery targets, display an avoidance behavior against spearfishermen likely as a consequence of fishing pressure. We suggest that the NTAs in Abrolhos are not only important sites for the recovery of fish stocks but also possibly act as a repository area of naïve fish (fish that allow human approach), for reefs open for fishing. RESUMO A pressão pesqueira afeta o comportamento de peixes recifais, especialmente nas espécies alvo de pesca. Nesse contexto é importante entender se áreas fechadas a pesca ("no-take areas": NTAs), consideradas como melhor instrumento para recuperação dos estoques pesqueiros, garantem a integridade dos comportamentos dos peixes. Comparar distâncias iniciais de fuga ("fligth initiation distance": FIDs) de espécies entre recifes de uso múltiplos ("multiple-use areas": MUAs), onde a pesca é permitida (incluindo a pesca submarina), e as NTAs é uma abordagem útil para testar se as NTAs podem ser efetivas como refúgios para peixes recifais. Nesse trabalho FIDs de duas espécies alvo (Sparisoma axillare e Scarus trispinosus ) e uma não alvo (Halichoeres poeyi ) foram comparadas entre MUAs e NTAs. A possível influência do tamanho do grupo ("group size": GS) e o tamanho do corpo ("body size": BS) sobre FID também foram investigados. Foram amostradas quatro MUAs e quatro áreas NTAs no banco dos Abrolhos (Brasil). Nossos resultados mostraram que apenas FID das espécies alvo de pesca foi menor dentro de NTAs e que o BS teve um efeito positivo no FID de todas as espécies. Dentro da NTA, GS e BS foram maiores do que em recifes abertos à pesca apenas para S. trispinosus . Finalmente, sugerimos que NTAs em Abrolhos não são apenas importantes como recuperação dos estoques pesqueiros, mas estão possivelmente atuando como uma área repositória de peixes "ingênuos" (peixes que permitem aproximação humana) para os recifes onde a pesca é permitida.

In Brazil, where reefs occur in markedly turbid environments, the relationship between sedimentation/organic matter and corals is poorly known. Thus, the ex situ effects of sediment with and without organic matter over the ΔF/Fm and physical state of Mussismilia braziliensis were analyzed. The ΔF/Fm and coral physical state, evaluated through the susceptibility index to sedimentation (SI), were measured in seven colonies exposed to sedimentation (0-450 mg cm(-2) day(-1)) free of organic matter after 45 days of exposure, and in 12 colonies exposed to sedimentation (0-500 mg cm(-2) day(-1)) with organic matter content (10%), in which case ΔF/Fm was measured after 72 h and SI after 120 h. In both cases there were effects of increasing sedimentation on the SI with no effect on ΔF/Fm. Despite the tolerance to high sedimentation rates shown by this coral, we noted that the presence of organic matter might reduce its tolerance to sedimentation stress.

Southwestern Atlantic Ocean rocky shores sustain important reef fish communities. However, those communities in tropical regions are not well understood, especially in Brazil. In this present article we assess community parameters of reef fishes such as composition, trophic organization and their relationships with physical and biological factors on four tropical rocky shores in Todos os Santos Bay, southwestern Atlantic. During six months, a total of 80 visual censuses were performed, in which 3,582 fish belonging to 76 species were recorded. Territorial herbivorous fish and turf algae were dominant at all the sites. The spatial variability of fish community structure was related to the benthic cover composition and depth. The high abundance of territorial herbivores and mobile invertebrate feeders could be associated with high levels of turf cover, low wave exposure and shallow waters. Moreover, this fact could be a consequence of the low density of roving herbivores and large carnivores probably due to the pressure of intense fishing activity. Thus complementary studies are needed to evaluate the actual conservation status of these rocky shore reefs, singularly located habitats connecting inner and outer reefs in Todos os Santos Bay. Resumo Os costões rochosos do Atlântico Sul Ocidental sustentam ricas comunidades de peixes recifais. Apesar disso, o conhecimento sobre essas comunidades em zonas tropicais continua escasso, especialmente no Brasil. No presente trabalho avaliamos parâmetros das comunidades de peixes recifais, tais como composição e estrutura trófica, além de sua interação com variáveis físicas e bióticas, em quatro costões rochosos tropicais na Baía de Todos os Santos, costa leste do Brasil. Durante seis meses 80 censos visuais foram realizados, nos quais 3.582 peixes pertencentes a 76 espécies foram registrados. Os peixes herbívoros territoriais e as algas filamentosas dominaram em todos os costões. A variação espacial na estrutura da comunidade de peixes esteve relacionada com a composição bêntica e profundidade. A elevada abundância observada de peixes herbívoros territoriais e invertívoros móveis pode ser devido à alta cobertura de algas filamentosas e à baixa profundidade e exposição às ondas. Além disso, esse padrão também pode ser explicado pela baixa densidade de herbívoros errantes e grandes carnívoros, provavelmente devido à intensa pressão da atividade pesqueira. Assim, novos estudos são necessários para avaliar o real estado de conservação destes ambientes, uma vez que estão localizados em posição singular na Baía de Todos os Santos, conectando recifes internos e externos da área.

Consequences of reef phase shifts on fish communities remain poorly understood. Studies on the causes, effects and consequences of phase shifts on reef fish communities have only been considered for coral-to-macroalgae shifts. Therefore, there is a large information gap regarding the consequences of novel phase shifts and how these kinds of phase shifts impact on fish assemblages. This study aimed to compare the fish assemblages on reefs under normal conditions (relatively high cover of corals) to those which have shifted to a dominance of the zoantharian Palythoa cf. variabilis on coral reefs in Todos os Santos Bay (TSB), Brazilian eastern coast. We examined eight reefs, where we estimated cover of corals and P. cf. variabilis and coral reef fish richness, abundance and body size. Fish richness differed significantly between normal reefs (48 species) and phase-shift reefs (38 species), a 20% reduction in species. However there was no difference in fish abundance between normal and phase shift reefs. One fish species, Chaetodon striatus, was significantly less abundant on normal reefs. The differences in fish assemblages between different reef phases was due to differences in trophic groups of fish; on normal reefs carnivorous fishes were more abundant, while on phase shift reefs mobile invertivores dominated.

We report the sighting of bonnethead shark Sphyrna tiburo juveniles

Submitted by Mendes Eduardo (dasilva@ufba.br) on 2013-07-15T17:37:27Z No. of bitstreams: 1 Dissertacao Miguel Loiola - Versao corrigida pronta.pdf: 2168745 bytes, checksum: 7e1032346a536c56e5455bf47c66afb8 (MD5) Approved for entry into archive by Ana Valéria de Jesus Moura (anavaleria_131@hotmail.com) on 2016-06-21T19:02:20Z (GMT) No. of bitstreams: 1 Dissertacao Miguel Loiola - Versao corrigida pronta.pdf: 2168745 bytes, checksum: 7e1032346a536c56e5455bf47c66afb8 (MD5) Made available in DSpace on 2016-06-21T19:02:20Z (GMT). No. of bitstreams: 1 Dissertacao Miguel Loiola - Versao corrigida pronta.pdf: 2168745 bytes, checksum: 7e1032346a536c56e5455bf47c66afb8 (MD5) Fapesb Atualmente, o aumento da sedimentação e do aporte de matéria orgânica são apontados como principais agentes causadores da devastação dos recifes de corais. Portanto este trabalho teve como objetivo investigar, em laboratório, os efeitos do aumento da sedimentação, associada ou não com matéria orgânica, sobre a fotossíntese, avaliada a partir da eficiência fotobiológica das zooxantelas associadas, e o estado físico do tecido, avaliado a partir de um índice quantitativo de susceptibilidade, de Mussismilia braziliensis, uma espécie de coral endêmico da Bahia e principal construtor do maior complexo recifal do Atlântico Sul. A susceptibilidade das colônias expostas ao sedimento sem matéria orgânica foi comparada com a susceptibilidade das colônias expostas ao sedimento com matéria orgânica. Os resultados encontrados possibilitaram a comparação com ecossistemas recifais mais estudados e também serão úteis para o manejo dos recifes contra impactos humanos. Os experimentos foram conduzidos em aquários do laboratório de Recifes de Corais e Mudanças Globais (RECOR). Para isso foram coletadas 19 colônias de M. braziliensis em um recife do arco costeiro de Abrolhos e sedimento lamoso no canal do rio Caravelas. No laboratório o sedimento foi preparado (lavado e secado) e separado em dois tratamentos, sendo um formado por sedimento com matéria orgânica e outro com sedimento sem matéria orgânica. O sistema experimental consistiu de 19 cubas de vidro de 4 litros, contendo água salina sintética a 36 psu, acondicionadas em aquários de 60 litros, com água doce circulante a 26°C, iluminados durante 12 horas diárias. Em cada cuba foi colocada uma colônia de M. braziliensis. Em sete cubas foram adicionadas concentrações de sedimento livre de matéria orgânica, equivalentes a 0, 15, 50, 150, 250, 350 e 450 mg.cm-2.dia-1. Nas 12 cubas restantes foram adicionadas concentrações de sedimento combinado com matéria orgânica equivalentes a 0, 15, 50, 100, 150, 200, 250, 300, 350, 400, 450 e 500 mg.cm-2.dia-1. Diariamente a água das cubas foi agitada por dois minutos para simular eventos de ressuspensão e deposição de sedimento. Para as colônias expostas ao sedimento sem matéria orgânica foi realizada uma análise de regressão linear simples entre a taxa de sedimentação e a susceptibilidade física das colônias, avaliada após 45 dias de exposição, a partir de um índice quantitativo de susceptibilidade à sedimentação. Para as colônias expostas ao sedimento associado com matéria orgânica, foram realizadas duas análises de regressão linear simples relacionando a taxa de sedimentação com a eficiência fotoquímica, estimada a partir do fluorômetro Diving-PAM, após 72 horas de exposição, e com o índice de susceptibilidade, após 120 horas de exposição. Após 120 horas de exposição foi comparada, através de um teste de Mann-Whitney, a susceptibilidade das colônias expostas ao sedimento sem matéria orgânica com a susceptibilidade de colônias expostas ao sedimento associado com matéria orgânica. Os testes de regressão mostraram uma relação positiva significativa entre a taxa de sedimentação e o índice de susceptibilidade das colônias de M. braziliensis expostas ao sedimento com e sem matéria orgânica associada. Para os dois conjuntos de colônias, entretanto, danos físicos severos foram encontrados apenas em colônias expostas a taxas superiores a 200 mg.cm-2.dia-1, que visaram simular impactos extremos como tempestades e dragagens. Diferente do esperado, o aumento da sedimentação não provocou a redução da eficiência fotobiológica das colônias expostas ao sedimento combinado com matéria orgânica. Os resultados encontrados são indicativos de tolerância à sedimentação e também da capacidade de fotoaclimatação dos corais de águas brasileiras, submetidos naturalmente a ambientes turvos. As colônias expostas ao sedimento associado com matéria orgânica apresentaram uma maior susceptibilidade à sedimentação, um resultado preocupante tendo em vista o aumento atual da poluição marinha como consequência do desenvolvimento costeiro e do mau uso da terra. The increase in sedimentation and organic matter are pointed out as the major agents responsible for impacting corals around the world. In Brazil, where reefs generally occur in markedly turbid environments and productive, the direct effects of sediment and organic matter elevation are poorly known. Thus, in a laboratory experiment, the effect of sedimentation associated with or free of organic matter over photosynthesis and tissue physical state of Mussismilia braziliensis were compared. Seven colonies of M. braziliensis were exposed to a sedimentation gradient (0 to 450 mg.cm-2 .day-1 ) free of organic matter. After 45 days of exposure, the physical health of corals was estimated, evaluated on the basis of a susceptibility index of sedimentation, developed in this work. Twelve colonies of M. braziliensis were exposed to a gradient of sedimentation (0 to 500 mg.cm-2.day- 1) with approximately 10% organic matter. After 72 hours dark adapted maximum photochemical efficiency was measured using a Diving-PAM (Walz, Germany) fluorometer, and after 120 hours, coral tissue state based on the susceptibility was evaluated. The comparison of the susceptibility index of colonies submitted to sediment with organic matter with the index of the colonies submitted to sediment free of organic matter resulted in a significant and positive relationship with sedimentation rate. However, no significant effect of sedimentation and organic matter was observed on photochemical efficiency of M. braziliensis zooxanthellae. This study showed that the Brazilian coral M. braziliensis is tolerant to sedimentation, and capable of producing energy via photosynthesis even in environments impacted by intense sedimentation and increasing organic matter. On the other hand, these results suggest that the increase of sedimentation interfere negatively in M. braziliensis tissue health and represents a greater menace to corals when sediment is associated with organic matter.

Non-lethal human disturbances are often drivers of change in animal population and community structure. To gauge their severity, short-term behaviour (e.g. avoidance and habituation) has been argued to be a sensitive measure. However, many of these behavioural changes may occur only if disturbance-free habitat is readily accessible. In coral-reef fish, we tested whether human disturbances from intensive (i.e. loud music, swimming, snorkelling, splashing and fish feeding by numerous visitors) tourist visitations resulted in assemblage structure shifts led by short-term behaviour. We monitored fish assemblage before, during and after tourist visitations to monitor changes associated with behaviour. Additionally, we monitored two adjacent reefs not visited by tourists because of difficult approach by boat. We posited that if short-term benefits of relocating to disturbance-free habitat outweigh the costs of tolerating disturbances, fish assemblage structure should shift along with tourist visitation levels. By contrast, if sensitive species are unable or unwilling to relocate, we predicted greater levels of assemblage heterogeneity between the visited and control reefs. Our results showed that in situ human visitations led to significant shifts in assemblage structure, resulting from short-term behavioural changes. Additionally, we showed significant between-reefs differences, whereby control reefs were characterised by higher species richness, larger fish sizes and variations in relative trophic guild prevalence. Our results suggest that short-term relocations to adjacent disturbance-free reefs may not mitigate the effects of human disturbances.