Banca de DEFESA: BRUNO CHARNAUX LONZETTI

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : BRUNO CHARNAUX LONZETTI
DATE: 31/03/2020
TIME: 09:00
LOCAL: online ao vivo nos sítios do Instagram (@brunolonzetti) e Youtube (https://youtu.be/NoLIl7UlQyc)
TITLE:

Can ocean warming help zoanthids outcompete branching hydrocorals?

KEY WORDS:

global change;biotic interactions;coral health;future predictions

PAGES: 40
BIG AREA: Ciências Biológicas
AREA: Ecologia
SUMMARY:

Given the spatial limitation in reefs, competitive interactions among sessile organisms often occur through physical contact, such as coral-seaweed competition. Ocean warming and acidification may affect the outcomes of these interactions, by changing the competitive ability and recovery potential of the interacting organisms. In the Southwestern Atlantic, one of the most important competitors to corals is the zoanthid Palythoa caribaeorum, which under warming scenarios may expand its distribution and likely dominate reefs, particularly in Northeast Brazil. If this occurs, it would likely outcompete the hydrocoral Millepora alcicornis, one of the most important species that adds structural complexity to Brazilian reefs. We studied the competitive interaction between the zoanthid (P. caribaeorum) and the hydrocoral (M. alcicornis) through field and laboratory experiments, particularly addressing: the effect of physical contact on the hydrocoral´s health (field and laboratory); the recovery potential of hydrocorals, once the contact is ceased (field and laboratory); and how ocean warming potentially affect these processes (laboratory only; 27°C vs. 30°C predicted for 2100). Additionally, as the competitive interaction may be potentially mediated by chemical compounds of the zoanthid, we extracted surface compounds and tested their effects on the hydrocoral in the field and in the laboratory under different temperature scenarios. We found that contact with the zoanthid caused more damage than with the mimetic control in the field and under 27°C after 24h of contact in the lab. Hydrocorals in the field did not recover over a short time span (10 days), but in the laboratory they partially recovered the damaged area in the same period, when under current temperatures (27°C). When under future temperatures (30°C), filamentous algae colonized the area of hydrocorals previously contacted by the zoanthid. Although hydrocorals presented similar symptoms when comparing the current and future temperature scenarios, the recovery potential decreased with warming as it favored colonization by filamentous algae. The greater damage observed in the field and on the first day at lab’s 27°C were signs of P. caribaeorum’s chemical activity favoring competition, which were confirmed with the chemical tests. Those tests indicated a chemical influence on the interaction and revealed that a 3°C raise in temperature makes any contact a damaging one. As ocean warms, the competitive interaction we studied will become more frequent and zoanthids more likely to overgrow the branching hydrocorals, and possibly other branching corals in areas where zoanthids are abundant, as in the Caribbean reefs, causing reef flattening and potentially loss of diversity. This highlights the importance of understanding how ecological interactions will be affected by global changes, as it allows us to predict future dominance scenarios.

BANKING MEMBERS:
Externa à Instituição - BÁRBARA SEGAL RAMOS - UFSC
Presidente - 2319234 - GUILHERME ORTIGARA LONGO
Externo à Instituição - IGOR CRISTINO SILVA CRUZ - UFBA