By Gene Yang ’19

Crustaceans play an important role in coastal ecosystems, an area of research that can provide new insight into climate change. A recent study found a correlation between body sizes of intertidal crustaceans, latitude, and sea-surface temperature.

A collaboration of researchers from six universities sampled the body sizes of four keystone crustacean species from 44 sandy beaches in California and Chile: high-shore amphipods (Orchestoidea tuberculata), mid-shore isopods (Excirolana braziliensis and E. hirsuticauda), and low-shore crabs (Emerita analoga). To reduce seasonal variability in body size, sampling was performed during the same time interval each summer over a period of three years. Body length of amphipods and isopods was defined as the distance from the rostrum tip to telson, and defined for crabs as the length of the carapace. Additional information such as the sea-surface temperature, life histories, and physical characteristics of the beaches was also recorded.

A regression analysis on the pooled data of each species, categorized by sex, found a significant macro-scale pattern across all datasets: crustacean body sizes decreased with increasing sea-surface temperature (4% – 35%). The p-values ranged from 0.01 for male O. tuberculata amphipods to 0.0009 for female E. analoga crabs. Due to the close relationship between climate and life histories, researchers also used these results to estimate the percentage decline of fecundity (10% – 68%) and biomass (49% – 71%) of these crustaceans amidst the predicted effects of climate change and warming oceans.

This research sampled a large but incomplete global latitudinal range (16%), so fieldwork in these other latitudes will be needed to conclude the certainty of these correlations. However, this study is significant because it matches the results of other past findings on body size patterns. Because crustacean body size can act as a predictor of metabolic cost, which indirectly affects populations and communities, its relationship to climate change is a concept that should be well-studied, with important implications for coastal conservation.

References

1. E. Jaramillo, et al., Macroscale patterns in body size of intertidal crustaceans provide insights on climate change effects. PLoS ONE 12, 1-24 (2017). doi: 10.1371/journal.pone.0177116.
2. Image retrieved from: https://upload.wikimedia.org/wikipedia/commons/9/96/Ghost_Crab_%28Ocypode_ryderi%29_by_hyper7pro_Flickr%2C_South_Africa.jpg