Oceanographic coupling across three trophic levels shapes source–sink dynamics in marine metacommunities

Abstract

A central goal of metapopulation ecology is to determine which subpopulations have the greatest value to the larger metapopulation. That is, where are the 'sources' that are most essential to persistence? This question is especially relevant to benthic marine systems, where dispersal and recruitment are greatly affected by oceanographic processes. In a single-species context, theoretical models typically identify 'hotspots' with high recruitment, especially high self-recruitment, as having the highest value. However, the oceanographic forces affecting larval delivery of a given species may also influence the recruitment of that species' predators, prey, and competitors.We present evidence from the Virgin Islands and Bahamas that oceanographic forces produce spatial coupling between the recruitment of planktivorous fishes, the recruitment of their predators, and the productivity of their zooplankton prey. We examined the consequences of this type of multi-trophic coupling using a simple analytical population model and a multispecies numerical simulation model with parameter values based on the Virgin Islands system. In both analyses, strong coupling caused planktivores at the highest recruitment sites to experience higher mortality (a consequence of higher predator densities) but faster growth and higher fecundity (a consequence of higher zooplankton densities) than planktivores at low recruitment sites. As such, the relative strength of oceanographic coupling between the three trophic levels strongly determined whether a particular reef acted as a source or sink. In the simulation model, density-dependent competition for zooplankton limited overall metapopulation biomass more severely than predation, so oceanographic coupling between planktivore larval supply and zooplankton productivity had a stronger effect on the metapopulation value of a patch. We argue that the potential for such tri-trophic coupling should be incorporated into future metacommunity models and has considerable implications for the design and evaluation of marine reserves.

Uniting paradigms of connectivity in marine ecology

“…For instance, nursery habitats can also benefit a species’ predators (Harborne et al. ) and larval dispersal of predators can covary with prey (White and Samhouri ) so that sheltered areas may also have higher predation mortality. Field experiments should thus seek to investigate the relative roles of predation interactions and meta‐population dynamics in shaping reef fish abundance.…”

Geographic coupling of juvenile and adult habitat shapes spatial population dynamics of a coral reef fish

“…This theory has predominantly been applied to understand terrestrial population dynamics (e.g., Boughton 1999, Kreuzer and Huntly 2003, Auestad et al 2010). More recently, source-sink dynamics have been used to understand marine metapopulations (Kritzer and Sale 2006), but mainly focused on differences in larval supply to distinct but connected populations due to ocean current patterns (James et al 2002, Bode et al 2006, Figueira 2009, White and Samhouri 2011 or habitat heterogeneity (Shima et al 2010). Although larval influx might determine the initial productivity of a habitat Manuscript received 29 September 2011;revised 11 February 2013;accepted 13 February 2013.…”

Reciprocal feedbacks between spatial subsidies and reserve networks in coral reef meta‐ecosystems

“…, ) and metacommunities (Baskett et al. , White and Samhouri , Gouhier et al. ), the joint effects of material transport and organismal dispersal on the optimal size and spacing of reserve networks for managing meta‐ecosystems remains largely unknown.…”

“…Overall, these different scales of material transport and organismal dispersal are expected to have a strong impact on the structure of communities across scales, the relative importance of local vs. regional processes, and the spatial management of interconnected ecosystems via reserve networks (Gaines et al. , White and Samhouri ).…”