Open vs. closed marine populations: Synthesis and analysis of the evidence

The major unanswered question in marine ecology is the degree of connectedness between local populations. Put another way, what proportion of young arriving into a local population are products of local production? What is the source of recruits for any local population, and where do the young produced in a local population go? The answers to these questions are unknown for any widespread species with a pelagic dispersal phase. Proper marine management depends on knowledge in this area: the efficacy of any reserve design, for example, is highly dependent on the degree to which it is dependent on other populations for recruitment, and the degree to which it supplies other areas.

Since most marine animals have a pelagic larval stage, the paradigm thus far has been to assume extensive dispersal and massive export. In contrast, I suggest that evidence is accumulating in a variety of fields (detailed below) that indicates a surprising amount of local retention, even in species with long larval durations. If such retention turns out to be a common feature of local marine population dynamics, this will require major reassessment of marine metapopulation models, fishery management schemes, marine reserve designs, and ideas about the mechanisms of marine speciation. It is time to assess the evidence for open populations (i.e., strongly connected local populations, best approached through metapopulation models) vs. closed populations (i.e., dependent on local production, similar to many terrestrial systems) in the marine environment.

An assessment of the prevalence of open vs. closed populations has been hampered by the diverse nature of the evidence. Many workers have pieces of the puzzle, and we need to gather them together. This proposal has two components:

1. A working group will convene to identify and share the most important areas of evidence, sources of data, and common methods of analysis. This group will consist of workers in the following areas:

2. As a Center Fellow, I will coordinate the group and work with NCEAS staff to help the group to gain access to and synthesize the evidence. Many in this group will not have realized the connections between their disciplines until they meet over this common problem, and most will not have analyzed their data from the perspective of open vs. closed populations. One of the most important tasks of this group will be to assess the evidence critically: what is evidence to indicate the degree of retention in a marine population, and what are alternative explanations for the patterns seen?