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Persistence and recovery of depleted marine invertebrates in marine reserves of central California.
Micheli, Fiorenza*,1, Heiman, Kimberly1, Kappel, Carrie1, Shelton, Andrew1, 1 Stanford University, Pacific Grove, CA, USA
ABSTRACT- An understanding of the processes that allow populations and communities to persist and recover following disturbance is critical to many important questions in ecology and conservation biology. Marine protected areas (MPAs) represent a powerful approach to conserving and promoting recovery of marine species and habitats impacted by fishing and other human activities. However, certain scenarios may prevent recovery or lead to further declines, even within MPAs. These include: extreme population reductions prior to protection; protection of unsuitable or degraded habitats; and intervening natural disturbances, such as extreme weather events, predation or disease outbreaks. We investigated patterns and processes of persistence and recovery of depleted invertebrate populations, red (Haliotis rufescens) and black (H. cracherodii) abalone, in central California. Abalone densities, size structure, and predation mortality were compared along a time-series of no take and de facto reserves (sites where access is limited by private property) established in central California between 1931 and 1997 and protected for varying lengths of time. Longterm persistence was examined within a permanent site established within a no-take marine reserve in 1972. Protection from human harvesting resulted in greater proportions of large individuals within intertidal but not subtidal habitat. Red abalone shows remarkably low fluctuations in densities and size structure over a 30 year period. Intense predation by sea otters in the subtidal habitat, combined with high recruitment rates may underlie these patterns.
Key words: recovery, predation, marine reserves, abalone