Marine life impacted by changing weather patterns

Unusual weather in Devon and Cornwall, with heavy rainfall and warmer summers, is reshaping coastal marine ecosystems. Rising sediment and nutrient levels threaten marine life, shellfish, and water quality, prompting ongoing monitoring to track environmental changes and risks.

Recent weather trends, including unusually wet winters and warmer summers, are significantly affecting coastal marine environments in Devon and Cornwall. Observations indicate that winter rainfall has reached record levels, resulting in increased sediment and pollutant loads in coastal waters. This situation presents risks to marine organisms, shellfish populations, and human health.

Meteorological analysis shows that rainfall during March in some areas of Cornwall and Devon reached roughly 150% of the long-term average. Additionally, February marked the wettest winter on record for Cornwall, as reported by official weather monitoring authorities.

Potential Long-Term Environmental Consequences

Experts warn that future winters characterized by mild temperatures, high rainfall, and strong winds may produce long-lasting effects on both terrestrial and marine ecosystems. Continuous monitoring by the Plymouth Marine Laboratory (PML) employs satellites and drones to measure bacterial and viral concentrations and to observe changes in algal populations along the coastline.

Impact of Sediment and Freshwater Influx

Dr. Gavin Tilstone, a bio-optical oceanographer at PML, noted that freshwater plumes from heavy rainfall can extend far into offshore waters. Large sediment plumes block sunlight, which adversely affects submerged vegetation such as seagrass and seaweed. These conditions may create favorable environments for harmful species impacting humans, fish, and shellfish. Sediment also contains high nutrient levels originating from agricultural runoff and sewage, which promote algal growth. During spring, algal blooms increase in frequency, including types toxic to marine life.

Persistent Sediment and Bacterial Hazards

Winter-accumulated sediment and nutrients can remain in coastal waters throughout the year. Sediment often settles on the seabed but can be disturbed by waves, while warmer water temperatures accelerate bacterial proliferation. Excessive sediment can smother marine vegetation, limiting growth. PML continues to conduct bacterial monitoring, testing samples for microbial concentrations, including E. coli, which can spike after heavy rainfall events.

The long-term environmental consequences are closely linked to weather during the following spring and summer. Persistent rain may trigger larger, potentially hazardous algal blooms, while hot and dry summers could substantially alter the coastal ecosystem.

Monitoring and Safety Measures

Bruce Newport, Area Environment Manager for Bathing Waters at the Environment Agency, explained the distinction between the work of PML and the agency. PML monitors a broad range of environmental parameters, whereas the Environment Agency focuses on sewage-related indicators. Although real-time testing is not possible, weekly summer sampling over the past three decades provides a thorough overview of bathing water safety. Public reports of water quality concerns are investigated promptly, and most beaches in Devon and Cornwall consistently maintain excellent conditions.

Newport added that while sewage incidents remain a concern, overall water quality has improved significantly over the past 10 to 15 years. Currently, approximately 98% of bathing waters meet high-quality standards, making identification of remaining pollution sources increasingly challenging.

Ongoing Research and Climate Implications

Research continues to assess the interactions between changing weather patterns, coastal water quality, and marine ecosystem health. Recent record rainfall highlights the variability of the climate and its potential impacts on both human activity and marine life along the Devon and Cornwall coastlines.

Sources:

• Plymouth Marine Laboratory - Coastal Water Monitoring
• BBC News - Extreme Weather Impact on UK Marine Life
• The Guardian - UK Marine Ecosystems Threatened by Weather Changes
• Wetter winter and warmer summer hit marine life