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Impact of Warming Oceans on Marine Species in UNESCO World Heritage Sites
Context:
A recent report by UNESCO and an analysis by Down to Earth reveal the significant effects of rising ocean temperatures on marine species within World Heritage sites. Nearly 20% of species are living in unsuitably warm waters, causing stress and affecting their well-being.
Key Findings on Marine Species and Thermal Limits
- 20% of species in 21 out of 51 UNESCO World Heritage marine sites have exceeded or reached their thermal limits.
- 881 species out of 4,406 mapped by the report are living beyond their thermal range, including 342 species of fish, 135 species of algae, and 76 species of molluscs.
- Species such as Atlantic bottlenose dolphins, West Indian manatees, and various sharks are living in areas with unsuitable water temperatures.
Impact on Marine Mammals and Fish
- Five species of mammals and seven species of sharks are exposed to unsuitable temperature ranges, including species like the Lesser sandshark, Caribbean reef shark, and Atlantic bottlenose dolphin.
- Marine mammals, such as female sperm whales, face challenges in reproduction due to high water temperatures affecting conception rates.
Regional Impacts of Ocean Warming
- The Belize Barrier Reef Reserve System has the highest percentage of species (53%) living in thermal limits.
- Coiba National Park in Panama and Everglades National Park in the US also show significant stress on species due to unsuitable temperatures.
- The Sundarbans in the Bay of Bengal recorded 19.8% of species living beyond thermal limits.
Ocean Heat and Species Behavior
- Rising ocean temperatures cause species stress, negatively affecting reproductive capacity and food availability.
- Warming waters have led to species migrating to cooler regions or deeper waters, such as the North Atlantic right whales and white-beaked dolphins, which are moving northward due to decreased food availability.
- Oxygen levels in the ocean are also affected by warming waters, influencing species survival and behavior. This disrupts the natural nutrient circulation in deeper waters.
Urgency for Emission Reduction
- The global sea surface temperature (SST) has increased by approximately 1°C over the past 140 years, accelerating species’ migration and stress.
- The IPCC report warns that higher emissions may result in a 4.4°C temperature rise by the century’s end, worsening the situation for marine biodiversity.
- Researchers emphasise the need for emission reduction to mitigate the impacts of warming oceans on marine life.
Role of UNESCO and New Research Methods
- UNESCO’s eDNA sampling method is being used to create inventories of marine biodiversity in World Heritage sites.
- The method helps map species distribution and track the impact of ocean warming on biodiversity across the globe’s oceans.
- These findings highlight the growing concerns about marine species living in thermal stress due to ocean warming and underscore the urgency of addressing climate change to protect marine life.
