Impact of Marine Heat Waves on Arctic Mammals

Marine mammals in the Arctic and Subarctic regions are facing challenges due to marine heat waves (MHWs). Recent studies indicate that these events lead to increased mortality, lower reproductive rates, and heightened disease susceptibility among these species. The Arctic Ocean is expected to become a hotspot for MHWs, which are defined as periods when sea surface temperatures exceed historical norms.

About Marine Heat Waves

Marine heat waves are defined by substantial increases in ocean temperatures over a period of days to years. These temperature anomalies must surpass the local 90th percentile threshold for at least five consecutive days. MHWs can cover extensive areas, affecting vast marine ecosystems.

Effects on Marine Mammals

The impacts of MHWs on marine mammals are deep. Species such as narwhals and bowhead whales struggle with thermoregulation due to their blubber, which can hinder heat dissipation. High mortality rates have been observed during prolonged warm periods, with species like humpback and fin whales affected.

Broader Ecological Impacts

MHWs do not only affect marine mammals. They also have cascading effects on various organism groups, including benthic species, phytoplankton, zooplankton, fish, and seabirds. The upper trophic level species, including seabirds and marine mammals, often exhibit delayed responses to MHWs due to their position in the food web and their longer life spans.

Health Risks and Disease Transmission

Increased temperatures can lead to toxic algal blooms and the spread of diseases. A concerning case was the first recorded mortality of a polar bear from avian influenza, likely contracted from infected marine birds. This marks the broader implications of MHWs on health and conservation for both marine mammals and humans.

Distribution Changes and Fishing Interactions

MHWs can alter the distribution of marine mammals and their prey. For instance, humpback whales have been observed to migrate southward, resulting in increased entanglement in fishing gear. While some Subarctic species may adapt by foraging further north, Arctic residents lack this option, leading to increased mortality and poor calf conditions.

Long-term Consequences

The long-term effects of MHWs include reduced populations and lower calf production rates among marine mammals. The ecological balance is disrupted, resulting in a decline in species that are already vulnerable due to climate change.

Future Projections

With ongoing climate change, the frequency and intensity of MHWs are expected to rise. This will pose further risks to the delicate Arctic marine ecosystem and its inhabitants. About these dynamics is crucial for effective conservation strategies.

Questions for UPSC:

1. Discuss the ecological implications of marine heat waves on Arctic marine mammals.
2. Critically examine the role of temperature in the distribution of marine species in the Arctic region.
3. Explain the impact of marine heat waves on the food web dynamics in marine environments.
4. With suitable examples, discuss the relationship between climate change and the emergence of diseases in wildlife.

Answer Hints:

1. Discuss the ecological implications of marine heat waves on Arctic marine mammals.

1. MHWs cause increased mortality and decreased reproductive rates among Arctic marine mammals.
2. Species like narwhals and bowhead whales struggle with thermoregulation due to blubber insulation.
3. High mortality rates have been recorded during prolonged warm periods, affecting species such as humpback and fin whales.
4. Changes in prey distribution lead to increased competition and stress on marine mammals.
5. Overall population declines and reduced calf production threaten long-term survival of affected species.

2. Critically examine the role of temperature in the distribution of marine species in the Arctic region.

1. Temperature acts as a key driver for the distribution of marine species, influencing habitat suitability.
2. Species are showing shifts in distribution towards cooler waters, impacting local ecosystems.
3. Warm conditions can lead to increased mortality and reduced foraging success in resident species.
4. Temperature anomalies can alter predator-prey dynamics, leading to unexpected interactions.
5. Some species may migrate northward, while others, especially year-round residents, face greater risks.

3. Explain the impact of marine heat waves on the food web dynamics in marine environments.

1. MHWs lead to changes in primary productivity, affecting the entire food web structure.
2. Upper trophic level species, like marine mammals and seabirds, exhibit delayed responses to changes.
3. Altered prey availability can create competition among marine mammals and other predators.
4. Toxic algal blooms resulting from warmer waters can harm various marine organisms, disrupting food chains.
5. Long-term effects include shifts in species composition and declines in vulnerable populations.

4. With suitable examples, discuss the relationship between climate change and the emergence of diseases in wildlife.

1. Climate change increases temperatures, promoting the growth of harmful algal blooms that can lead to toxic exposure.
2. The first recorded polar bear mortality from avian influenza marks disease transmission risks in warming climates.
3. Warmer waters can stress marine mammals, making them more susceptible to infections and diseases.
4. Changes in species distribution can facilitate pathogen spread among wildlife populations.
5. Overall, climate change creates conditions that may enhance disease emergence and threaten wildlife health.