Theres a new paper out by Edgar et al in Ecological Applications that tracks the ecosystem effects of 14 MPA’s, and exploited companion sites, in southern Australia and Tanzania over a 16 year period.
The effects of the MPAs are interesting: biomass of large predators is on a steep increasing trend, while prey-species such as grazing molluscs and urchins are on a downward slope. I wonder what this will lead in terms of macroalgal abundances?
Another interesting finding is that
recently declared MPAs across Australia have been systematically located in areas with few fishery resources. Stakeholders with fishing interests presumably lobbied successfully against the “locking up” of exploitable fish stocks in SZs
I’ve stumbled upon many ecologists who tend to think that MPA’s are almost always designated in pristine areas, thus confounding interpretations of whether they are effective, i.e “the protected sites are healthy, not because they’re protected, but because they were healthy in the first place”. Those with more insights into how local resource users think and work will probably disagree on this, and usually claim the contrary, i.e. “people are pretty darn good at maneuvering the MPA-creation process so as not to include their best fishing grounds”. This study provides compelling evidence of the latter:
The abstract summarizes things nicely:
Tasmanian reef communities within ‘‘no-take’’ marine protected areas (MPAs) exhibited direct and indirect ecological changes that increasingly manifested over 16 years, eventually transforming into communities not otherwise present in the regional seascape. Data from 14 temperate and subtropical Australian MPAs further demonstrated that ecological changes continue to develop in MPAs over at least two decades, probably much longer. The continent-scale study additionally showed recently established MPAs to be consistently located at sites with low resource value relative to adjacent fished reference areas. This outcome was presumably generated by sociopolitical pressures and planning processes that aim to systematically avoid locations with valuable resources, potentially compromising biodiversity conservation goals. Locations that were formerly highly fished are needed within MPA networks if the networks are to achieve conservation aims associated with (1) safeguarding all regional habitat types, (2) protecting threatened habitats and species, and (3) providing appropriate reference benchmarks for assessing impacts of fishing. Because of long time lags, the ubiquity of fishing impacts, and the relatively recent establishment of MPAs, the full impact of fishing on coastal reefs has yet to be empirically assessed.