Colony size-frequency distributions among different populations of the scleractinan coral Siderastrea stellata in Southwestern Atlantic: implications for life history patterns

Abstract

A B S T R A C TColony size-frequency distributions of reef corals may be used to infer growth potential and population responses upon environmental changes. The present paper compares the size structure of colonies of Siderastrea stellata Verrill, 1868, among 11 sites, six of them distributed along a gradient of sediment deposition in Abrolhos, Bahia, Brazil (18 o S). Results indicated that the population structure is likely to be influenced by local conditions, rather than large scale factors, such as latitude. The 11 distributions, however, showed higher frequencies of small size classes. Class 1 (up to 2.5 cm diameter) was always present and the frequency of colonies from size class 3 (10 cm diameter) tended to decrease in all sites. Comparison among the six Abrolhos sites showed that S. stellata has advantages at sites with intermediate sedimentation, where colonies attain larger sizes, probably, reflecting a higher survivorship over time. The present study showed that, despite the influence of environmental conditions on parameters of the populations such as size of colony, the life history strategy of S. stellata reflects a local adaptation that allows its development and survivorship in shallow waters and horizontal substrates, sites characterized by high mortality rates. R E S U M ODistribuições de freqüências de classes de tamanho de colônias de corais recifais, associadas a dados de fecundidade e crescimento, podem ser utilizadas para inferir o potencial de crescimento e respostas da população frente às variações ambientais. Apresentamos análise da estrutura de tamanho de colônias do coral Siderastrea stellata Verrill, 1868, em 11 locais, seis desses distribuídos ao longo de um gradiente de sedimentação em Abrolhos, Bahia, Brasil (18 o S). Os resultados demonstraram ausência de um padrão latitudinal, indicando maior influência de fatores locais. Em Abrolhos, locais com taxas de deposição de sedimento intermediárias apresentaram os maiores coeficientes de variação e tamanhos médios, indicando condições mais propícias para o desenvolvimento de populações desse coral na região. As 11 distribuições, porém, apresentaram maior freqüência de classes pequenas. A classe 1 (colônias com diâmetro médio de até 2,5cm) ocorreu em todos os locais. A partir da classe 3 (10 cm em diâmetro) as freqüências diminuíram consideravelmente. Esses dados, associados ao fato da espécie se reproduzir cedo e incubar larva, refletem uma estratégia de sobrevivência, em águas rasas e substratos horizontais, caracterizada por alta taxa de mortalidade e tempo de vida curto.

Variation in size frequency distribution of coral populations under different fishing pressures in two contrasting locations in the Indian Ocean

“…Assessing size structures of coral populations can provide information about important ecological processes such as coral survivorship, recruitment, fecundity, mortality and community responses to various stress events such as mass coral bleaching or Acanthaster plancii outbreaks (Meesters et al, 2001;McClanahan et al, 2008). Records of coral size class distributions and frequencies can provide an in-depth understanding of trends in the condition and resilience of reef ecosystems, rather than the data offered from more simplified metrics such as coral cover or diversity (Bak and Meesters, 1998;de Barros and Pires, 2006;Meesters et al, 2001).…”

Coverage Increases of Porites astreoides in Grenada Determined by Shifts in Size-Frequency Distribution

“…Weedy corals with a shared life history strategy may compete with each other in disturbed environments [56]. Large colony size is typical of stress-tolerant species, with a greater reserve of polyps from which to draw energy, often increasing the resilience of these colonies to changes over time [57].…”

Thermal stress and tropical reefs: mass coral bleaching in a stable temperature environment?

“…Oigman-Pszczol and Creed (2011) suggested that the large number of smalldiameter colonies is an adaptive reproductive strategy developed in reefs subject to environmental stress. Another important factor is that this species tends to reproduce early and incubate larva (Barros and Pires 2006). This phenomenon may be the consequence of a survival strategy under turbid conditions, temperature anomalies, and resuspension of sediments, all of which were present in our study site, which was characterized by high mortality rates and short life spans (Soares et al 2017).…”