Coral reefs are spectacularly important living structures.
- protect coastal communities from powerful storm surges
- protect vulnerable coastlines from erosion
- are home to a variety of animals, from seahorses to sharks
- provide important refuge for many species
- supply food for species in other ecosystems (including to humans)
- offer valuable economic services to humans, such as for recreation
- supply invaluable benefits, like carbon sequestration, nutrient cycling
Despite their value, coral reefs only cover less than 1% of the worlds oceans (explore maps here).
Coral reefs are fragile and gravely threatened. Many coral reefs have suffered more than 90% coral death in the last couple decades, with very high death rates in the last year.
Threats to corals include:
- nutrient pollution (e.g., from farms or human sewage – even when very diluted)
- seawater temperature rise
- ocean acidification (caused by too much carbon in the atmosphere, going into the ocean)
- habitat degradation or loss (e.g., mining, aquaculture, farming)
- sediment loading (e.g., from land development)
- invasive species
- cyanide & bomb fishing
- fishing for the aquarium trade
- African dust carrying disease causing bacteria
This Netflix film, Chasing Coral, nicely documents the impact of climate change causing coral bleaching & death.
My personal research efforts have discovered that:
- nutrient pollution from human wastewater makes it to barrier reefs, even if they are far offshore and water tests appear clean
- nutrient pollution causes coral killing sponges to explode in size and number
- reef sharks are largely absent where they were once common
- methods of censusing reef communities have overestimated the abundance, and biomass of mobile fishes. There may be orders of magnitude fewer top predators than some studies suggest. Correction values indicate, for example, that inverted biomass pyramids on reefs may be a result of this observer bias. Correction estimates for underwater visual censuses found here.
- reef sharks in Thailand are abundant enough to be observed by divers, and that some populations may be threatened.
Tools I use for this work include:
- field assessments
- isotope chemistry
- computer simulations
- historic video footage