Modeling Planktonic Larval Dispersal Patterns to Improve the Design of Marine Protected Areas

Humans have depended on the goods and services of marine ecosystems for millennia, and the effects of our influences on them are evident. In particular, fishing has profound effects on marine ecosystems. Targeting of top predators, fishing down the food web and indiscriminate and destructive fishing practices are among the human actions which threaten the very ecosystems on which we depend. One solution can be found in marine protected areas (MPAs), regions where fishing or other human activity are restricted or prohibited. MPAs are commonly planned according to socioeconomic concerns; however, ecological considerations like larval dispersal should be taken into account in order to create efficient MPAs. Many marine organisms spend part of their life cycle in a larval stage, in which their movement is controlled largely by the currents. Short-range dispersers can be effectively protected by small MPAs, but MPAs of sufficient size to encompass the dispersal zones of long-range dispersers may be logistically and economically infeasible. Networks of small MPAs linked by current-controlled larval dispersal can serve as a viable alternative. The life histories and habitat preferences of giant clams, octopi and tuna are discussed in terms of suitable MPAs and MPA networks for these three groups of organisms of differing life histories. The dispersal distances calculated for each group are applied with Geographic Information Systems (GIS) to a case study of the Banda and surrounding seas of Indonesia , to evaluate the efficiency of Indonesia 's MPAs at protecting these organisms. According to this study's model, there is little networking by giant clam larvae between Indonesia 's MPAs, although sites for potential MPAs to create networks with existing MPAs exist. Octopi and tuna larval dispersal distances are too long to make accurate predictions of dispersal zones possible, but Indonesia 's MPAs contain a large amount of suitable octopi habitat. Tuna are likely effectively protected in the MPAs which surround small island groups. More detailed scientific data would allow more precision in this model, but it should form the basis for ecological evaluation of potential MPA sites using GIS. Spatial analysis of ecological characteristics should accompany the evaluation of socioeconomic concerns in order to formulate effective MPAs which meet both socioeconomic and ecological goals.