Stressed fish and bleached anemones
Hard corals are not the only organisms that bleach in warming ocean conditions. Anemones also host similar photosynthetic algae which convert sunlight into energy, but the relationship between the anemone and the algae can be disrupted during environmental disturbances. When anemones on a coral reef bleach, they may either recover or die if the environmental stress persists. Large anemones are best known for their relationship with clown fish, which use the anemone as a home and a safe place for their eggs. Although the clown fish don’t feed on the anemones, clown fish tend to decrease in abundance and decrease their reproductive output when anemones are bleached.
Recent research, published in the journal Proceedings of the Royal Society suggests that these impacts on clown fish may be due to an increased “cost of living” demand in stressful environments. To study the response of clown fish to anemone bleaching, the researchers monitored clownfish interacting with bleached anemones in a controlled environment. They measured oxygen consumption of the fish as a metric of basal metabolic demand. Their results show that clown fish living with bleached anemones had a higher basal metabolic rate than those with healthy anemones. This increased in basal metabolic rate may have implications for the health of clown fishes in the future as there may be less energy available for important tasks, like swimming, reproduction, or escape from predators.
Read the full study here:
Norin T et al. 2018. Anemone bleaching increases the metabolic demands of symbiont anemonefish. Proceedings of the Royal Society B DOI: 10.1098/rspb.2018.0282