Protected areas have been implemented worldwide to preserve diversity and maintain ecosystem function. Marine Protected Areas (MPAs), which often restrict commercial and recreational fishing and foreshore development, have been shown to increase fish abundance and biomass, compared with unprotected, or partially protected areas.

However, an overarching goal of MPAs is to maintain community stability – so are they actually doing this?

We used a 10-year snorkel survey in Batemans Marine Park in southern NSW to test whether changes in the identity of fish species (turnover) varies between sites that are protected (MPAs), unprotected (OPAs = outside park areas), and partially protected (PPAs – where recreational fishing is still allowed).

Snorkel survey at Batemans Marine Park
Photo credit: Bill Barker

We found that MPAs have a greater capacity to retain species through time, as shown by more shallow zeta diversity decline (i.e., turnover), compared with unprotected (OPAs) and partially-protected (PPAs) areas. This was particularly important for large-bodied harvested species, including red morwong and bream.

Our decadal study provides evidence that MPAs are working – in Batemans Marine Park protection produces stabilising effects on fish diversity. Whether these results hold more generally across other marine parks, and whether MPAs can also confer resilience to fish communities in the face of environmental change still needs to be determined.

This work was funded by the RAAP grant awarded to SIMS and IMOS by the NSW Governmment, and survey work done by Nature Coast Marine Group, and is now published in Conservation Biology. See ‘publications’ or contact me for a PDF copy.