Climate Change Impacts on Seabirds and Marine Mammals

A new review published in Ecology Letters, a peer-reviewed scientific journal, assessed seabird and marine mammals’ responses to climate change and climate variability. Researchers based their analysis on data from more than 480 preexisting studies and found that “the likelihood of concluding that climate change had an impact increased with study duration”.

In other words, detecting the influence of climate change on certain species requires long-term observations. Furthermore, the analysis posits that species which had more limited temperature tolerance ranges and relatively longer generation times were reported to be most affected by changes in climate. (Generation times are temporal intervals between the birth of an individual organism and the birth of its offspring).

Seabird species: Australian Pelican (Pelecanus conspicillatus)

How Does Climate Change Affect Marine Life?

From the 484 peer-reviewed studies that matched researcher’s inclusion criterion, 2,215 observations were compiled into a database and mapped. This includes 1,685 observations for seabirds and 530 observations for marine mammals. 54% of observations for seabirds were distributed towards northern hemisphere (39% of observations from temperate and polar regions). For marine mammals, 83% of observations were distributed toward the northern hemisphere (53% of observations from temperate and polar regions). For both seabirds and marine mammals, tropical and subtropical regions represented a mere 8% of total observations.

What Marine Life Is Most Affected by Climate Change?

Authors of the preexisting studies found 38% of total observations to be related to climate change, 49% were attributed to climate variability, and 13% were attributed to both. Reproductive success and adult survival were the most common response variables studied on both taxonomic groups (60% for seabirds and 34% for marine mammals). According to the new review, “a significant majority of observations concluded that climate change had an effect on both the seabird and marine mammal groups for all the response classes”. Response classes include demography, distribution, condition, phenology, behavior and diet.

How Does Climate Change Affect Marine Biodiversity?

The longer the duration of the original studies, the more likely authors were to infer that the observed changes in taxonomic groups were due to climate change rather than climate variability. 189 of the preexisting studies (669 observations) that demonstrated climate change effects had a time span above the estimated average threshold of 19 years. Generally, studies on marine mammals were able to demonstrate climate change responses based on shorter time scales (17± 5 years) versus seabirds (22 ± 3 years).

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