Impact of Warming Waters on Marine Life

Why in News?

According to a recent analysis by Down To Earth (DTE), nearly 20% of species residing in UNESCO’s World Heritage marine sites have lived in unsuitable warm waters.

• Global sea surface temperature (SST) – At present, it is roughly 1 degrees Celsius higher than 140 years ago, according to National Oceanic and Atmospheric Administration.
• The warmest future climate scenario or SSP 8.5 (best estimate projected warming of 4.4°C by the end of the century).
• Impact – Ocean heat content has impacted all the 6 major oceans since 1998.
• But the most significant warming has been in the southern oceans.
• Induce migration – Ocean warming is shifting marine species into cooler and deeper waters from their natural habitats.
  • Warming waters have compelled white-beaked dolphins found in cooler North Atlantic waters to move north-west from the southern areas during 1991-2017.
• Impacts reproduction of mammals – Female sperm whales are unable to conceive at their known rates due to warm waters.
• Affect survival rates of mammals – As species migrate for new suitable waters, they become more vulnerable to new pathogens.
• Affect water movement – It impacts oxygen levels between the surface waters and deeper waters that naturally circulates, providing nutrients to marine species.
• Alter species behaviour – For instance, bacteria which use oxygen as fuel has now switched to nitrate, eventually releasing nitrogen gas and impacting water and atmosphere characteristics.
• Thermal limit breaching – 881 of 4,406 species studied have breached their thermal limits includes.
• UNESCO’s eDNA Expeditions inventoried 21 of 51 marine sites have exceeded their living thermal limits.

Environmental DNA (eDNA) is an on-invasive sampling method developed by UNESCO, maps ocean life and create an inventory of marine biodiversity in 21 of its 51 World Heritage marine sites.

References

1. Down to Earth| Impact of Warming Waters on Marine Life
2. UNESCO | World Heritage Marine
3. UNESCO| Environmental DNA Expeditions