Invertebrate health in marine protected areas (MPAs)

The reported effects of MPAs are overwhelmingly positive, with numerous reports of fish size (biomass), abundance (recovery) and diversity increases, however, literature is lacking on the role of MPAs on parasite and disease dynamics, and in particular, invertebrate health.

This review paper aimed to consolidate extant literature and provide a comprehensive viewpoint on how invertebrates (and their health status) can be affected by MPAs, which are increasingly being implemented based on the relative urgency now being placed on protecting global biodiversity.

It compiles information showing both potentially positive and negative effects of MPAs in relation to invertebrate’s health status. For example, in some MPAs changes in species assemblages and population abundance have been shown to have negative effects due to overcrowding, or variation in food web structure due to changes in competition or predation rates. On the other side, there are as well many examples showing that MPAs also act as tools for alleviating impacts of marine disease. No-take marine reserves have been shown to control the recovery of populations after mass mortality events and recent studies have shown that well conserved seagrass ecosystems reduce exposure to bacterial pathogens of humans, fishes, and invertebrates, by effectively filtering them out.

It is also highlighted that the lack of knowledge about the diversity and abundance of pathogens in marine ecosystems makes it difficult to establish the relative importance of disease and when this is most likely to occur in an MPA. It is expected that a pathogen profile would change as an MPA develops but little is known about the microbiome or pathogen profile of species in MPAs at present.

The author concludes that due to the lack of physical boundaries and fluid movement of waterborne pathogens, mitigating disease threats is challenging in marine environments, especially in MPAs. This review also highlights the paucity of knowledge surrounding MPAs and disease, especially that of the unenigmatic invertebrate groups, and stresses the need for better baseline monitoring of both invertebrates and marine disease before MPA implementation as well as ongoing adaptive management.

Davies (2021) Invertebrate health in marine protected areas (MPAs). Journal of Invertebrate Pathology