Plastic pollution and climate change
We use sea anemones as model organisms to study the effects of plastic pollution and global warming on coral reefs. In a recent work, we introduced plastic fibers to tanks containing either bleached or unbleached (symbiotic) anemones, and then examined their ability to deal with plastic pollution.We found that all of the anemones would take up plastic fibers, especially when coated with food as they might be in the natural environment. However, the healthy anemones were able to eject the indigestible plastic from their body cavities much faster than the bleached anemones.
This work suggests that plastic pollution and high ocean temperatures (caused by global warming) together are likely to deliver a bigger blow than would be expected by looking at each threat separately. Therefore, coral reef organisms that are susceptible to both bleaching and plastic pollution (e.g., corals and anemones) may be at even greater risk than previously recognized.
In-situ metabolic measurements on coral reefs
Coral reefs cover a small portion of the world’s ocean but are one of the most biologically diverse ecosystems in the planet. They provide goods and services to millions of people and protection to the coast. However, human induced stressors, such as increases in seawater temperature, are threatening the health of this ecosystems. In 2016 and 2017, Lizard Island, located at the northern part of the Great Barrier Reef, experienced massive bleaching events which led to widespread coral mortality. Coral degradation resulted in shifts in the dominant benthic biota on the reefs, from reef-building to non-reef-building communities such as turf algae. One of my recent projects aimed to study the influence of those shifts on coral metabolism. To do so, we deployed two Coral In-Situ Metabolic and Energetics (CISME) instruments concurrently at the healthy (coral covered) and degraded (algal) parts of mounding coral colonies and calcification rates were compared on light and dark scenarios. The coral- and algal-covered reefs showed similar positive calcification rates during the day. However, nighttime respiration on the surfaces covered by turf algae drove carbonate dissolution. It is not clear whether the dissolving carbonate is from calcifying organisms living in the algal turf or whether it is the underlying coral substrate. The surprising result of daytime positive net calcification on a dead coral skeletal surface suggests a more complex balance between calcification and dissolution than previously assumed.
Ocean acidification and metal pollution
Carbon dioxide capture and storage (CCS) in submarine geological formations has been proposed as a mitigation measure for global warming. This technology involves trapping emissions of greenhouse gases, particularly CO2, from the main single-point sources like fossil fuel power plants and industrial processing sites, and subsequently injecting and storing the gases underground. However, leakage of CO2 may occur over time, leading to the acidification of sediments and overlying water.
In collaboration with colleagues, I developed a CO2 leakage simulator in the laboratory to evaluate the risks of a CO2 leakage from storage sites. I collected contaminated sediments in Spain and Brazil and performed experiments to analyze the effects of acidification on the chemical fractionation of metals in sediments, on metal mobilization and speciation as well as on the toxicity to marine biota. Check out my list of publications to read about the exciting results we obtained from these experiments.