O aquecimento dos oceanos pode ajudar zoantídeos a superar competitivamente hidrocorais ramificados?
Competitive interactions between sessile organisms in reef environments generally occur through physical contact, given the spatial limitation in these environments. Ocean warming is one of the factors that can affect the outcomes of these interactions, changing the competitive ability and recovery...
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| Formato: | Dissertação |
| Idioma: | pt_BR |
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Universidade Federal do Rio Grande do Norte
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| Endereço do item: | https://repositorio.ufrn.br/jspui/handle/123456789/30087 |
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| Resumo: | Competitive interactions between sessile organisms in reef environments generally occur through physical contact, given the spatial limitation in these environments. Ocean warming is one of the factors that can affect the outcomes of these interactions, changing the competitive ability and recovery capacity of the organisms. The Intergovernmental Panel on Climate Change predicts and average increase of 3 °C in the temperature of the Atlantic Ocean for the year 2100, under highest greenhouse gas emission projection. The hydrocoral Millepora alcicornis is one of the only branching coral species in Brazil, contributing to structural complexity in reef environments. The zoanthid Palythoa caribaeorum is one of the most important coral competitors in the Western Atlantic. Both species compete with each other from the coast of Florida to southeastern Brazil. If M. alcicornis withstands the 3 °C increase in temperature, it will continue to compete with P. caribaeorum, which will still occur in reef areas in the Caribbean and northeastern Brazil, despite minor distribution shifts. Going beyond predictions of species distribution, the effect of ocean warming on species interactions is poorly known. Because interactions can be modulated by ocean warming, we studied the competitive interaction between P. caribaeorum and M. alcicornis through field and laboratory experiments, addressing in particular: the effect of physical contact on the health of M. alcicornis (field and laboratory); the recovery potential of M. alcicornis after the end of contact (field and laboratory); whether this interaction is mediated by chemical compounds present on the surface of P. caribaeorum (field and laboratory); and how ocean warming can affect these processes (laboratory: 27 °C vs. 30 °C). We found that physical contact with P. caribaeorum causes more damage than with its control in the field and in the laboratory at 27 °C. The recovery of M. alcicornis in the laboratory at 27 °C and in the field occurred within 10 days. Filamentous algae colonized the area of M. alcicornis that had contact with P. caribaeorum in the laboratory at 30 °C, jeopardizing its recovery. Contact with chemical extract of P. caribaeorum in the laboratory at 27 °C and in the field caused more damage to M. alcicornis than contact with its control. Contact with the extract and its control caused equal damage to M. alcicornis in the laboratory at 30 °C. Our results indicate that P. caribaeorum outcompete M. alcicornis through physical and chemical mechanisms, and that an increase of 3 °C in the ocean temperature impairs the recovery of M. alcicornis and makes the physical aspect of contact more important than the chemical. The rate of P. caribaeorum overgrowth in M. alcicornis tends to increase with the intensification of this interaction as the ocean warms, which can lead to a loss of structural complexity and, consequently, of diversity in reefs in the Caribbean and Brazil. Understanding how ocean warming can affect competitive interactions in reef environments is essential to project the future of these ecosystems. |
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