Ecosystem Dynamics in Marine Heatwave-Affected Coastal Environments

Marine heatwaves (MHWs) are discrete, extended periods of anomalously high sea temperatures that are intensifying under climate change. Such events impose acute stress on coastal ecosystems, disrupting physical, chemical and biological processes across multiple scales. At the base of the food web, shifts in phytoplankton and zooplankton composition alter energy transfer, while habitat-forming species such as kelp and seagrasses experience die-offs or range contractions. Changes in nursery function of estuarine and nearshore environments compromise juvenile survival and growth, with consequences for fish stocks, fisheries and coastal communities. Trophic cascades emerging from altered forage fish dynamics and top predator demands can lead to reproductive failures, mass mortalities and range shifts of seabirds, marine mammals and groundfish. Prolonged heatwave conditions can leave legacies in ecosystem structure, as novel community assemblages persist long after peak temperatures subside. Understanding organismal acclimatisation, community reorganisation and ecosystem resilience is essential to inform adaptive management, early warning systems and conservation strategies in a warming ocean.

Research from Nature Portfolio

Recent studies demonstrate how individual, population and community responses interlink under marine heatwave conditions. One investigation of juvenile Pacific cod showed that nursery habitats lose buffering capacity during heatwaves, leading to reduced abundance of small individuals and the emergence of a few large “super survivors” that may reflect selective pressures on growth and survival. Long-term monitoring in the Gulf of Alaska has revealed that ecosystem responses to a prolonged heatwave persisted for at least five years, with abrupt shifts across trophic levels and novel groupings of species that did not revert to pre-heatwave states. At the base of the food web, transcriptional analyses of a dominant copepod species uncovered regional gene-expression patterns indicative of physiological plasticity, suggesting that local acclimatisation mechanisms contribute to resilience in highly seasonal environments.

Ecosystem Dynamics in Marine Heatwave-Affected Coastal Environments publication trend

The graph below shows the total number of articles in ecosystem dynamics in marine heatwave-affected coastal environments across all publications each year (not limited to Nature Index journals).

Technical terms

Marine heatwave: A prolonged period of anomalously high sea temperature relative to historical baselines.

Nursery habitat: A coastal area that provides essential shelter and food resources for juvenile stages of marine organisms.

Phenology: The seasonal timing of biological life-cycle events, such as spawning or migration.

Trophic level: The position of an organism within a food-web determined by its source of nutrition.

Physiological plasticity: The capacity of an organism to adjust its physiological processes in response to environmental changes.

References

1. Impact of the 2014–2016 marine heatwave on US and Canada West Coast fisheries: Surprises and lessons from key case studies. Fish and Fisheries (2023).
2. Marine heatwaves alter the nursery function of coastal habitats for juvenile Gulf of Alaska Pacific cod. Scientific Reports (2024).
3. Warmer, earlier, faster: Cumulative effects of Gulf of Alaska heatwaves on the early life history of Pacific cod. Elementa: Science of the Anthropocene (2024).
4. Heatwave‐induced synchrony within forage fish portfolio disrupts energy flow to top pelagic predators. Global Change Biology (2021).
5. Ecosystem response persists after a prolonged marine heatwave. Scientific Reports (2021).
6. Regional heterogeneity impacts gene expression in the subarctic zooplankter Neocalanus flemingeri in the northern Gulf of Alaska. Communications Biology (2019).