Co-tutelle PhD candidate from Federal University of Rio Grande do Norte - Brazil and James Cook University - Australia. Has experience in ecological interactions with corals, coral reef monitorings,

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

2022 to 2025

Project Description

The objective of this Ph.D. research is to understand how competitive interactions between hard corals and macroalgae, soft corals, and zoantharians, differ across a range of ecologically-relevant and present and future environmental scenarios. To achieve this objective, the prevalence and outcomes of competition for corals with different evolutionary histories and from vastly different environments (southwestern Atlantic and Indo-Pacific reefs) will be investigated. A combination of field observations and laboratory experiments with controlled environmental conditions will be used to uncover the environmental variables that have the largest influence on the outcomes of competition. More specifically, this thesis aims to answer the following questions in four chapters:
Chapter 1: Are the outcomes of competitive interactions between hard corals and macroalgae and zoantharians influenced by the proximity of individuals?
Chapter 2. Does iron enrichment, a common element associated with mining pollution, affect competitive interactions between hard corals and macroalgae and zoantharians?
Chapter 3. How does nutrient concentrations and ocean acidification affect the outcomes of hard coral - soft coral interactions?
Chapter 4. Does a soft coral differentially affects two species of branching hard corals while competing?

Project Importance

Environmental changes of anthropogenic origin are transforming reef ecosystems, often leading to higher abundance of fast-growing organisms like macroalgae, zoanthids, and soft corals. These changes in benthic composition can alter the frequency and intensity of competitive interactions among these major benthic groups. While numerous studies have investigated the mechanisms and outcomes of competitive interactions between hard corals and other benthic taxa, relatively few have considered whether and how these will be affected by ongoing anthropogenic stressors. Specifically, little is known of the effects of anthropogenic environmental pressures on interactions between hard corals with macroalgae, zoantharians, and soft corals.

Project Methods

Three out of four researches have already been concluded through a series of laboratorial experiments conducted in other institutions (in Brazil and Germany). 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 mainly through changes in their photosynthetic efficiency and visual damages in their tissue along time.

Project Results

So far, the results of this research have indicated that competition involving hard corals are species-specific. While some coral species can endure competition and thrive, others are severely affected. 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.

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