Environmental determinants of suitable habitat and the prediction of a southern shift in the future distribution of spiny lobsters, genus Jasus

Climate change is altering environmental conditions which is affecting species habitats globally. As a result, many species are shifting their habitat ranges poleward to ensure that they remain within their optimal thermal range. On average, marine species have shifted their ranges poleward by approximately 72km to track their optimal thermal conditions compared to 17km for terrestrial species. These range shifts are pushing some species out of their currently fished areas. This will require nations and fishery companies to predict the most likely areas their target species could move to and obtain permits to fish in those new areas. Spiny lobsters (genus Jasus) are likely to shift their ranges poleward as they are distributed within a relatively tight latitudinal band, but there is limited information about the extent of any potential range shifts. The aims of this study were to identify the environmental variables that characterise the current habitat locations of lobsters within the genus Jasus, and to predict their potential distribution by modelling future suitable habitat under the RCP45, RCP60, and RCP85 climate scenarios using MaxEnt. There were 16 environmental variables used for modelling suitable habitat for the present (2000-2014), while only four environmental variables were available for modelling in two future time periods (2040-2050 and 2090-2100). There was a predicted overall southern shift in suitable habitat locations for all species. The most important environmental variable identified for species distributed along continental shelves (J. edwardsii and J. lalandii) was benthic temperature. Benthic nutrients (silicate, nitrate, and phosphate) were the most important variables for species distributed around islands and on seamounts (J. paulensis, J. frontalis, and J. tristani). Approximately 90% of Jasus lobsters present range contained highly suitable habitat locations. The percent of highly suitable locations under the RCP45 and RCP60 scenarios were higher than the present percentages for each species, while under the RCP85 scenario, there was a decrease of highly suitable habitat for most species in 2040-2050 period, while for the 2090- 2100 period, there was an increase in the percent of highly suitable habitats. This study provides evidence that Jasus populations might become more abundant in the southern extents of their current range as they track their optimum habitat conditions.