Biologia reprodutiva de Madracis decactis (Lyman, 1859) (Cnidaria, Scleractinia) de recifes do sul da Bahia, Brasil

The reproductive biology of the scleractinian coral Madracis decactis (Lyman, 1859) was studied in southern Bahia reefs, the most extensive and richest reef areas of the South Atlantic. Madracis decactis is one of the most widespread zooxanthellate corals in Brazil and can be found at the edges of the reefs on exposed or cryptic areas. The objective of this study was to investigate patterns of the sexual reproduction of M. decactis. Information about sexuality, gonad arrangement, mode of development, gametogenesis and temporal patterns of the reproductive cycle were obtained using histological procedures. The results showed that M. decactis is a hermaphroditic species and probably presents a brooding mode of development in southern Bahia reefs. Reproductive cycle is annual and lasts about four months. Female and male gametes started to develop at different times, with spermaries appearing in approximately the second month of oogenesis and lasting about two months. Gametogenesis started on the summer onset (December) and was complete at early autumn (April). Mature gametes were not present in samples collected between the end of March and April. Evidences suggested that fecundation, embryogenesis and the possible planulae release occurred within this period, of approximately one month.A biologia reprodutiva do coral escleractíneo Madracis decactis (Lyman, 1859) foi estudada nos recifes do sul da Bahia, a mais extensa e rica área recifal do Atlântico Sul. Madracis decactis é um dos corais zooxantelados mais amplamente distribuídos do Brasil, podendo ser encontrado nas bordas dos recifes em locais expostos ou abrigados. O objetivo deste estudo foi investigar padrões na reprodução sexual de M. decactis. Informações sobre sexualidade, arranjo das gônadas, modo de desenvolvimento, gametogênese e padrões temporais do ciclo reprodutivo foram obtidas através de procedimentos histológicos. Os resultados mostraram que M. decactis de recifes do sul da Bahia é uma espécie hermafrodita e provavelmente incubadora de larvas. O ciclo reprodutivo é anual e dura cerca de quatro meses. Gametas masculinos e femininos começaram seu desenvolvimento em momentos diferentes, com cistos espermáticos aparecendo aproximadamente no segundo mês da ovogênese e durando cerca de dois meses. A gametogênese se iniciou no começo do verão (dezembro) e completou-se no princípio do outono (abril). Não foram observados gametas maduros nas amostras coletadas entre o final de março e abril. Evidências sugeriram que a fecundação, a embriogênese e a possível liberação de plânulas ocorreram dentro desse período, com duração de cerca de um mês

Population structure and physiological plasticity of Favia gravida with differences in terrestrial influence

Terrestrial runoff is a source of sediments and nutrients to coral reefs. Due to runoff, Brazilian reefs are typically turbid, and have coral species that are naturally turbidity-resistant. This study investigated how terrestrial input influences population and physiology for the coral Favia gravida on two reefs with differences in river mouth proximity in eastern Brazil. The population structure and physiological traits of F. gravida colonies were assessed on both reefs, then some colonies selected for a subsequent transplantation experiment. The reef less impacted by terrestrial influence showed higher population density and lower recruitment. At this site, the coral colonies displayed higher calcification and larger larvae. The reproductive effort between coral populations at the two sites showed no significant difference. The transplantation experiment confirmed the high physiological plasticity of F. gravida colonies at the more turbid reef site. Despite being regarded as a more challenging environment, where F. gravida has a lower population density, the reef closer to the river mouth appears to secure more nutrients, which may heterotrophically compensate its coral colonies

Inclinação de Assentamento de Larvas e Adultos do Coral Recifal Favia Gravida em Recifes de Porto Seguro, Bahia, Brasil

A successful reproduction is the first step in coral larvae recruitment on the reefs. Substrate types, as well as its orientation may affect coral recruitment, growth and survival rates. The current study was made at Porto Seguro, BA, Brasil, and aimed to observe planulation pattern, verifying the settlement preference of larvae on three different substrate slopes - horizontal, vertical and inclinated (45o) and evaluate the slope preference of Favia gravida adult colonies in different reefs of Porto Seguro, BA. Adult colonies were taken to aquariums and observed until planulation. Recently released larvae were transferred for aquariums with recruitment plates. These plates were examined after the 21st day of planulation. Porto Seguro most common reef types were sampled regarding adults occurrence: “coastal reefs”, the top of a patch reef or a reef flat, and the internal wall of a large lagoon inside Recife de Fora. Colonies slope were measured using a graduated arc and a float or weight (for negative positioned colonies) placed at the base of each colony, comprising a total of 540 colonies, 180 in each reef sampled. The larvae did not present a preference for substrate slope. Since adult colonies were commonly found at slightly steep upper surfaces, it is suggested that differential mortality may have happened with larvae in other surfaces. As Favia gravida larvae did not present strict slope preferences, and based on the knowledge that adults tend to occur at moderate steep surfaces, the results suggest this is the most suitable orientation for recruit introduction in Porto Seguro reefs in rehabilitation activities of degraded environmental, to certify most recruits survivorship in long term.O sucesso na reprodução é o primeiro passo para o recrutamento de corais nos recifes. O tipo de substrato, bem como a sua orientação, pode afetar o recrutamento, crescimento, e taxas de sobrevivência de corais. O presente estudo teve como objetivos observar o padrão de planulação, verificar a preferência de assentamento de larvas em placas com diferentes inclinações - horizontal, vertical e inclinada (45o) e analisar a inclinação preferencial de colônias adultas do coral Favia gravida em diferentes recifes de Porto Seguro, BA. Colônias adultas foram mantidas em aquários e acompanhadas até a planulação. As larvas recém liberadas foram transferidas para aquários com placas de recrutamento. Estas foram triadas a partir do 21o dia após a última adição de larvas. Os principais tipos recifais encontrados em Porto Seguro foram amostrados: recifes costeiros, o topo de um “cabeço”, e a borda interna de uma das piscinas naturais do Recife de Fora. A inclinação das colônias foi determinada com a ajuda de um transferidor e uma bóia ou peso (para inclinações negativas) posicionando-o junto à base da colônia, totalizando na medição de 540 colônias, 180 por local amostrado. As larvas não apresentaram preferência por uma determinada inclinação durante o assentamento. Como as colônias adultas de Favia gravida foram encontradas com maior freqüência em superfícies superiores e ligeiramente inclinadas no substrato recifal, sugere-se que pode haver mortalidade diferencial das larvas assentadas em outras posições. Não havendo restrição de inclinações para assentamento das larvas de F. gravida e sabendo que adultos da mesma espécie tendem a ocorrer em superfícies inclinadas superiores, os resultados sugerem que esta seja a orientação mais adequada para implantação de recrutas nos recifes de Porto Seguro em atividades de recuperação de ambientes degradados, garantindo assim, uma maior sobrevivência dos recrutas a longo prazo

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear un derstanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5–7 vast areas of the tropics remain understudied.8–11 In the American tropics, Amazonia stands out as the world’s most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepre sented in biodiversity databases.13–15 To worsen this situation, human-induced modifications16,17 may elim inate pieces of the Amazon’s biodiversity puzzle before we can use them to understand how ecological com munities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple or ganism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region’s vulnerability to environmental change. 15%–18% of the most ne glected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lostinfo:eu-repo/semantics/publishedVersio

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5,6,7 vast areas of the tropics remain understudied.8,9,10,11 In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepresented in biodiversity databases.13,14,15 To worsen this situation, human-induced modifications16,17 may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost