Impacts of Climate Change on the Ascension Island Marine Protected Area
and its ecosystem services
Abstract
This is the first forecast of marine circulation and biogeochemistry for
the Ascension Island Marine Protected Area (MPA). MPAs are a key
management tools used to safeguard ocean biodiversity from human
impacts, but their efficacy is increasingly threatened by anthropogenic
climate change. To assess the vulnerability of individual MPAs to
climate change and predict biological responses, it is first necessary
to forecast how local marine environments will change. We found that the
MPA will become warmer, more saline, more acidic, with less nutrients,
less chlorophyll and less primary production by the mid-century. A
weakening of the Atlantic equatorial undercurrent is forecast in all
scenarios. In most cases, these changes are more extreme in the
scenarios with higher greenhouse gases emissions and more significant
climate change. The mean rise in temperature is between 0.9
\degree C and 1.2 \degree C over the first
half of the 21st century. The integrated primary production and
nutrients are forecast to decline in the MPA, but there is less
consistency between models in projections of salinity, surface
chlorophyll, and dissolved oxygen concentration at 500m depth. The
combined effects of these projections may lead to changes in ecosystem
services around Ascension Island. The effects of the model outputs were
interpreted for three key ecosystem service providing habitats: biogenic
deep sea habitats, intertidal sand and intertidal rocky shores. The
outcomes were then used to assess potential effects on eight marine and
coastal ecosystem services and information was compared to current
ecosystem service levels.