Post provided by Chi-Yun Kuo

Predicting the effects of ocean warming is vital to understanding the potential impacts of climate change on marine ecosystems. In this post, Chi-Yun Kuo shares knowledge from his latest publication in Methods in Ecology and Evolution which develops a framework for assessing the effects of water heating on marine fish communities and discusses the implications for conservation, food security and other ecosystem services.

Global warming is causing sea temperatures to rise and this alarming trend is projected to continue until the end of the century and beyond. Since marine fish are important food sources and provide other ecosystem services, estimating what would happen to these communities in a warming ocean is an urgent task at the intersection of ecology, conservation, and fisheries.

Four of the species represented in the analysis, including species important for commercial fisheries such as Atlantic cod and cod. Credit: Wikimedia Commons

Warming can affect marine fish in many ways, but most will change (1) where the species occur, (2) their rhythm of life (or life history), and (3) the way they interact with the species. others. The effects of heat on marine fish cannot be fully assessed without considering these three important aspects.

An integrative framework for assessing heat impacts

Understanding the need for an integrative framework to assess heat impacts, we developed a method that uses information from distribution forecasts, life history changes, and food network dynamics to examine how species and communities will respond. a warming ocean.

Our framework rests on the shoulders of several well-defined methods, including species distribution models, global life history analyzes, and the size-based food network model with the R package. mizer. By integrating these methods into the same analysis, our framework allows us to examine how the size distribution of individuals would change within species under warming and how resistant the community as a whole would be to large-scale concerns.

Integration of existing models into a new framework. Arrows show how information on species distribution and life history is included in size-based food networks. Variables in red are directly affected by temperature. Credit: Kuo etj. 2022

We applied our method to the community that inhabits the continental shelf along the east coast of the United States and found:

  1. Heating generally reduces species biomass, the percentage of smaller individuals within the species, and the maximum size.
  2. Accurate responses to heat vary between species.
  3. Heavier heating makes the community more vulnerable to concerns, especially concerns that eliminate larger individuals from the community. Eventually, the community is still able to return to the state before the riots.

Who can use our method?

Our method would be of interest to various scholars and policymakers. Ecologists can use our method to address questions such as: what kind of species would be most affected by warming. Is this related to specific taxonomic groups? Species living in tropical, subtropical or temperate regions? Or species that live at specific depths in the water column?

Conservation biologists, fisheries scientists and policymakers can use our method as a heuristic tool to visualize the future of their warming communities of interest and to develop conservation measures for species that may be most vulnerable. Given the fact that marine fish constitute an essential food source in many regions of the world, the results from our method can be used in conjunction with economic models to assess the impact on food production. Although our method can be easily applied to any marine community, a global data set would use the full potential of our method to answer large-scale questions: what would happen to marine fish if warming continued and what can this mean for human populations?

Relative distribution of individuals of different sizes within each species. The red curves are
sizes under the current climate, the green curves are the less severe ones and the blue ones
the turns are those under the strongest heat.

You can read the full paper in Methods in Ecology and Evolution:

Assessing the effects of heat on marine fish by integrating physiology-driven distribution projects, life history changes, and dynamic food networks

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