Predicting the future distribution of a commercially important clam (Ruditapes philippinarum) in a changing climate

The Manila clam, Ruditapes philippinarum, is a valuable commercial species for aquaculture, which in 2020, accounted for 24 % of global mollusc aquaculture. Given its economic importance, there is concern over whether this species may be vulnerable to the effects of climate change including changes in its distribution and sustainability. To test its vulnerability to climate change, we used Maximum Entropy (MaxEnt) modelling to predict both its current distribution and its future distribution under climate scenarios for end-of-century with focus on temperature and salinity changes. Future scenarios identified widespread local and regional changes in suitability. Across northern Europe and Alaska, a combination of continued or increased suitability for R. philippinarum was predicted. However, in the Mediterranean, and especially around Italy who are a major aquaculture producer of Manila clams, habitat suitability is predicted to decrease by more than 50 %. In Asia, especially below 20° N and above 40°N latitudes, habitat suitability is predicted to markedly increase but decrease dramatically between these latitudes. This is particularly the case along the coastline of China; the current global leaders in Manila clam production. Our results suggest the long-term sustainability of this species in countries like China and Italy may be threatened by climate change and action may be needed to conserve this species and support industry. Elsewhere, in countries like Norway, Alaska and Indonesia where increases in suitability are predicted in the future, expansion and/or investment in clam aquaculture production may represent an opportunity for economic growth and sustainable food production.