Recently, the team led by Academician Wei Fuwen from the Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou) comprehensively analyzed monitoring data of global ocean fish communities since the 1960s, revealing the profound impacts of climate change and fishing activities on the characteristics of global ocean fish communities. The related findings were published in "Conservation Biology."
Climate change is reshaping the global marine ecosystem, causing widespread changes in fish species communities, manifested as species turnover and characteristic shifts. Despite numerous empirical studies from local to continental scales, considering the heterogeneity of the marine environment and regional biases, the overall patterns of global fish community responses to ocean climate change still require further investigation.
The research team assessed the long-term changes in key features of global ocean fish communities, including the community-weighted temperature index (i.e., the average thermal affinity of community fish), weighted average body length, and trophic level. These indicators respectively reflect the physiological, morphological characteristics, and nutritional status of marine fish communities. By applying spatial linear mixed models, they explored how ocean temperature changes and fishing activities influence the community's weighted average trait values, as well as the relative abundance of different body lengths and trophic groups.
The study found that the global ocean fish community temperature index showed a preliminary upward trend, indicating the phenomenon of "ocean tropicalization," while the weighted average body length and trophic level exhibited a downward trend. This suggests that temperate marine areas are more vulnerable to climate change. Furthermore, there was no evidence that communities influenced by warm and cold ocean currents showed differences in the degree of tropicalization.
Combining spatial linear mixed models of sea surface temperature trends and fishing activity intensity revealed a positive correlation between ocean warming and the increase in the community's weighted average body length and trophic level. Fishing activities exacerbated the response of fish community temperature index to climate warming. A lower sea temperature baseline appears to mitigate the impact of climate warming on trophic levels. Additionally, the impact of climate warming on the relative abundance of fish of different trophic levels and body lengths followed a non-linear pattern, with small and relatively large fish potentially benefiting, while medium and largest fish may face greater challenges.
Based on these conclusions, the research team calls for the establishment of a more interconnected network of marine protected areas and a reduction in human disturbances to mitigate the rapid tropicalization of fish communities, especially in sensitive temperate marine areas.
Related Paper Information: https://doi.org/10.1111/cobi.14291
