Diverse seafloor life helps ecosystems recover from marine heatwaves

Jenn Hoskins
14th January, 2026

Diverse seafloor life helps ecosystems recover from marine heatwaves

This study simulated an in-situ heatwave in New Zealand's Waihī Estuary (a–c) using Open Topped Chambers equipped with temperature loggers (d) to investigate the resilience of the local macrobenthic community's functional traits.

Image adapted from: Lam-Gordillo et al. / CC BY (Source), using base imagery from Land Information New Zealand.

Key Findings

  • This New Zealand estuary study simulated a heatwave to understand its impact on seafloor organisms
  • Heatwave exposure reduced the abundance and diversity of seafloor organisms, but functional traits remained largely unchanged
  • The resilience observed suggests seafloor communities possess redundancy in functional traits, allowing them to maintain ecosystem processes despite heat stress
Ocean ecosystems are facing increasing stress from climate change, primarily through rising water temperatures and the growing frequency of extreme heat events. These events, including heatwaves (HWs) and marine heatwaves (MHWs), disrupt marine life and threaten the health of entire ecological communities. A key question for researchers is understanding how these communities cope with, and recover from, heat stress.[1] New Zealand Institute for Earth Science, Flinders University, and Universidade do Minho (UMinho) researchers have recently investigated this issue through a unique experiment examining the impact of simulated heatwaves on seafloor communities. The study focused on macrobenthic communities – these are the organisms living in and on the sediment of the seafloor – in intertidal estuarine environments. Intertidal zones are particularly vulnerable to temperature fluctuations, making them ideal locations to study the effects of heat stress. The research team conducted an in-situ experiment, meaning the warming was applied directly to the natural seafloor environment, rather than in a laboratory setting. This approach provides a more realistic assessment of how communities respond to heat stress. They used two different durations of simulated heatwave to assess the impact of varying exposure times. Previous research has established a clear trend of increasing marine heatwave frequency and intensity globally[2]. This increase in mean ocean temperatures is a primary driver of these changes, and scientists have observed a 34% increase in marine heatwave frequency and a 17% increase in duration from 1925 to 2016. More recently, 2023 saw record-breaking marine heatwave activity, with events exceeding historical norms by a significant margin[3]. Understanding the mechanisms behind these events is critical, and studies have shown that factors like enhanced shortwave flux, reduced cloud cover, and oceanic advection all play a role in driving MHWs in specific regions. The experiment by revealed that the simulated heatwave did affect the abundance and diversity of macrobenthic organisms. However, surprisingly, the study found less impact on the functional traits and associated functional metrics of the community. Functional traits are the characteristics of organisms that determine their role in the ecosystem – for example, how they feed, how they move, or how they reproduce. Functional metrics are measurements of these traits across the entire community. The resilience observed suggests that the community possessed a degree of redundancy in its functional traits. This means that multiple species performed similar functions, so if one species was negatively affected by the heatwave, others could step in and maintain the overall ecosystem processes. This finding builds on earlier work that identified the Southern Ocean as a key region for ocean heat uptake[4]. While[4] focused on the physical mechanisms driving heat absorption, the study highlights a potential consequence of this heat uptake: a shift in community structure that doesn’t necessarily translate to a loss of ecosystem function, at least in the short term. The ability of the Southern Ocean to absorb heat may be buffering some of the impacts on biodiversity by allowing for functional redundancy to maintain ecosystem processes. The researchers also noted idiosyncratic responses – meaning that different species reacted to the heatwave in unique and unpredictable ways. This highlights the complex nature of marine community responses to thermal extremes and the importance of considering the specific context of each environment. Maintaining diversity in functional traits and redundancy within those traits appears to be a key factor in promoting ecosystem resilience under increasing climatic stress.

EnvironmentEcologyMarine Biology

References

Main Study

1) Redundancy of macrobenthic functional traits boosts resilience to a simulated heatwave

Published 12th January, 2026

https://doi.org/10.1371/journal.pone.0340819

Related Studies

2) Longer and more frequent marine heatwaves over the past century.

https://doi.org/10.1038/s41467-018-03732-9

3) Record-breaking 2023 marine heatwaves.

https://doi.org/10.1126/science.adr0910

4) Drivers and distribution of global ocean heat uptake over the last half century.

https://doi.org/10.1038/s41467-022-32540-5


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