Longo, Guilherme OrtigaraInagaki, Kelly Yumi2024-07-162024-07-162024-03-08INAGAKI, Kelly Yumi. Diferentes perspectivas das interações ecológicas entre corais, algas e herbívoros. Orientador: Dr. Guilherme Ortigara Longo. 2024. 122f. Tese (Doutorado em Ecologia) - Centro de Biociências, Universidade Federal do Rio Grande do Norte, Natal, 2024.https://repositorio.ufrn.br/handle/123456789/58801Ecological interactions involve all organisms and ecosystems that we know. In reef environments, corals and algae are important organisms that interact with each other in positive, negative, or neutral ways, and their interactions are influenced by top-down (consumer-mediated) and bottom-up (producer-mediated) effects. Reefs and their complex interactions are threatened by local impacts and global climate change, which may alter the patterns and outcomes of these interactions. In this thesis, we explored the ecological interactions among corals, algae, and herbivores from different perspectives. In Chapter I, we conducted a systematic review covering the last 20 years of studies (2001-2020) and investigated: i) where these interactions have been most explored globally; ii) the main organisms involved; iii) the most frequent outcomes of these interactions; iv) the effects of herbivores; and v) the effects of climate change on the interactions. We observed that: (i) 86% of ecological interactions were explored in the Pacific and Caribbean regions; ii) the main groups involved are massive and branched corals and macroalgae and turf, with some variations between regions; iii) adult corals are mostly harmed by algae, suffering sublethal damages, while juvenile corals may be both benefited and harmed particularly through recruitment; iv) most studies evaluate herbivory effects on coral-algal interactions indirectly (e.g., abundance correlation), with few experimental efforts; and v) the effects of climate change were explored in only 10% of the studies, negatively affecting coral recruitment or causing sublethal effects, as well as reducing algal abundance. In Chapter II, we explored the effects of coral interaction on algal palatability to herbivores from a global perspective and found that herbivores prefer to feed on algae near coral edges. This pattern is observed in tropical reefs of the Caribbean and South Atlantic, potentially originating from differences in algal palatability due to contact with corals. In Chapter III, we explored coral-algae-herbivore interactions on a tropical reef in Brazil, seeking to understand: i) the relationship of their historical abundances; ii) the current frequency of coral-algal interactions; iii) the outcome of these interactions for corals and algae; iv) how ocean warming could influence these interactions; and v) whether different herbivores could mediate coral-algal interactions in the present and in warming scenarios. We observed that i) benthic cover has remained stable over the last decade, reflecting even older records, with algae dominance (60%) and low coral cover (~6%), a scenario that does not seem to relate to local herbivorous fish biomass; ii) coral-algal interactions are frequent, with 96% involving the coral Siderastrea stellata mainly interacting with turf algae; iii) most of these interactions lead to a decrease in coral photosynthetic efficiency, but vulnerability varies among coral species; iv) coral-algal interactions in warming scenarios remain equally detrimental to corals when compared to interactions at current temperatures, with variations among species; v) the dominant macroalgae are poorly consumed by different herbivores, regardless of temperature, indicating little effect on coralalgal interactions. In Chapter IV, we explored the effects of iron enrichment on algal palatability, evaluating different concentrations (control, 100 µg/L, 300 µg/L, 900 µg/L) at three exposure times (days 0, 13/14, and 27/28). We found that different iron concentrations do not affect algal palatability, but we observed higher consumption at the average exposure time, probably due to the balance between chemical defense production and algal integrity. Thus, we explored coral-algae-herbivore interactions, highlighting global and regional patterns that challenge a prevailing paradigm in marine ecology that herbivory would be the primary factor in mediating coral-algal interactions.Acesso AbertoSiderastrea stellataPorites astreoidesMillepora alcicornisDictyopteris delicatulaPalatabilidade de algasMudanças climáticasdoctoralThesisCNPQ::CIENCIAS BIOLOGICAS::ECOLOGIA