Ana was born and grew up in Mexico while raised by a Brazilian family. She undertook her studies in Biological Sciences in Brazil, and specialized in the marine environment when she studied her Master’s degree, diving into coral reef ecology. She worked in several reef monitoring projects along the Brazilian coast, including Reef Check Brazil, until she decided to undertake a PhD in the Federal University of Rio Grande do Norte, Brazil, to uncover competitive interactions in experimental environments. At the same time, she started her PhD at JCU as a cotutelle candidate, where she studied onshore for one year, developing experiments at Orpheus Island Research Station and at AIMS.

Effect of global and local environmental stressors on benthic competition on coral reefs

2022 to 2025

Project Description

Competition is one of the strongest interactions shaping communities, especially in reef ecosystems where space is limited for sessile organisms. Anthropogenic environmental disturbances can negatively affect hard corals, declining their abundance and shifting the dominance to other benthic taxa like macroalgae, zoantharians, and soft corals, that can outcompete hard corals for reef substrate. The four chapters of this thesis aim to investigate the mechanisms of competitive interactions between corals and other organisms and how they can be affected by environmental stressors, through a combination of laboratory experiments with corals species from distinct reef environments (Southwestern Atlantic and Indo-Pacific reefs). In the first two chapters I investigated mechanisms and outcomes of competition involving hard corals from the Southwest Atlantic and the Indo-Pacific, competing with common local competitors: macroalgae and zoantharians in the first case, and soft corals in the second. Then I assessed the effects of iron enrichment on competition between three hard corals and a macroalga and a zoantharian, based on mining disasters that have occurred in the Brazilian coast. Finally, I investigated separate and combined effects of nitrate pollution and acidification on competition between a hard and soft coral from the Indo-Pacific. Overall, this thesis demonstrates different responses of hard corals to competition with other organisms under distinct scenarios, and the results will enable more accurate forecasts of the consequences of increasing stressors predicted for the future on reef ecosystems.

Project Methods

A combination of field observations and laboratory experiments with controlled environmental conditions were used for this research. For each chapter, a different laboratory experiment was conducted, taking place in several laboratory facilities (i.e., UFRN and Coral Vivo Project, Brazil; ZMT, Germany; Orpheus Island Research Station and AIMS, Australia). Basically, competitive interactions were simulated between hard corals and competitors, and the effects of competition (and of abiotic variables, when present) were measured in hard corals through changes in their photosynthetic efficiency, growth, visual damages in their tissue, among other specific measurements (e.g., Chl-a, Simbiodiniaceae).

Project Results

This research indicates that competition involving hard corals are species-specific. While some coral species can endure competition and thrive, others are severely affected. Results from the first and second chapter show that most hard corals were damaged after interacting physically with the competitors, but their susceptibility to damage depended on the species involved. On the other side, competitors such as macroalgae, zoantharians, and soft corals seem to be affected in a lesser extent by competition with hard corals. Abiotic factors like acidification and pollution can also differentially affect corals while competing. In the third chapter, competition was deleterious for all hard corals irrespective of iron pollutant, but high iron enrichment was significantly harmful to an endemic species while competing. And the last chapter indicated that, while the hard coral was negatively affected by competition, acidification combined with nitrate enrichment either aggravated or mitigated these negative effects, depending on their combination and concentrations.

Keywords

Algae,
Benthic,
Climate change,
Coral reefs,
Corals,
Ecology,
Field based,
Interaction,
Management tools,
Manipulative experiments,
Monitoring,
Ocean acidification,
Ocean warming,
Physiology,
Pollution,
Rocky reefs