The deep ocean is under threat from climate warming, and now a new study conducted by the ICM-CSIC has shown just how much trouble these fish are in. The research revealed that with an increased global temperature of 4°C, deep sea fish have been found to shrink in size by 35%. Fish otoliths discovered in geological formations, which have traced back up to 700–800 thousand years, were used in this study to reach this conclusion. The findings are not only concerning to ocean life, but also the fishermen who rely on the deep sea fisheries for their income. As the world continues to warm, it is more important than ever to be aware of the dire effects on the deep ocean and its inhabitants.
Warming Temperatures Put Deep Sea Fishes and Fisheries at Risk
In recent studies, scientists have begun to investigate the effects of climate warming on organisms in mesopelagic zones, the small but abundant fish living at depths of 200-1000 meters below the surface of the ocean. Lanternfishes, one species of these deep-sea fish, play an important role in the stability of ocean ecosystems, as well as in reducing atmospheric carbon dioxide levels. Lanternfishes make up more than half the fish biomass in the deep sea and are important contributors to the biological carbon pump, transporting carbon from the surface down to deeper waters. It has been documented that lanternfishes travel hundreds of meters up to the surface of the ocean to return carbon to the depths.
Knowing the response of these organisms to ocean warming is key, since they contribute to ecosystem stability, reduce atmospheric carbon dioxide, and are a huge food resource for other organisms in the marine food web”, explains the ICM-CSIC researcher and co-author of the study Marta Coll, who adds that “these fish make up more than half the fish biomass in the deep sea, and about 100 times more than the total global annual fishery catches.
Marta Coll, ICM-CSIC researcher and co-author of the study
The effects of climate warming on deep-sea fishes is a cause for worry. With warming temperatures, researchers fear that these fish may shrink over time due to reduced food availability and increased metabolic costs at higher temperatures. This is because smaller fishes are more efficient swimmers and feeders than their larger counterparts, allowing them to survive better under high temperatures. Thus, shrinking sizes of deep sea fish could reduce ecosystem stability and weaken its ability to sequester carbon from our atmosphere. These changes also put pressure on fisheries dependent on deep ocean resources- with fewer big fish, commercial fishing industries face a future of dwindling catches and economic losses.
Climate change has many harmful effects on the environment, and the effects are far-reaching. One of the most concerning changes is the decrease in size of deep ocean fish due to increasing ocean temperatures. Not only are these creatures being put at greater risk of extinction, but they are also essential to many marine ecosystems and fisheries. It is imperative that we take steps to reduce global warming and its effects on our planet so that the deep ocean fish population continues to thrive for future generations.
