Role of the early benthic phase in regulating the distribution and abundance of marine invertebrate populations.

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The abundance of benthic (i.e. bottom-dwelling) marine invertebrates, such as oysters, barnacles, lobsters and seastars, varies by as much as 400% over time (year to year) and space (from one location to another). These remarkable variations in abundance have negative effects on the stability of natural communities and on the availability of species that are commercially harvested, yet the causes of these variations are not well understood. Increasing evidence suggests these variations are at least partly caused by low (0-40%) and variable levels of survivorship through the first few days or weeks of benthic life (i.e. the early benthic phase), when these animals are still in the larval or early juvenile forms. It is not known, however, to what extent variation in population abundance is caused by variation in survivorship through the early benthic phase. The proposed project will significantly advance our understanding of the role of this early benthic phase in controlling population abundance. The intertidal barnacle Balanus glandula will be used as a model organism in experiments that quantify two consequences of early benthic mortality: its influence on the abundance of the cohort after the early benthic phase up to maturity, and also on the ability of species to colonize habitats. This study will also examine the responses of 7 species of intertidal animals, including barnacles, mussels, hermit crabs and snails, to a range of climate conditions. It will determine the extent to which populations of these intertidal animals differ in their ability to tolerate warmer temperatures and reduced ocean salinities, and the impacts of changing climate conditions on their abundance. The study will provide breakthroughs in our ability to predict population abundance and the type of habitats these species can colonize, helping us understand why early benthic survivorship is so low and variable, and leading to predictions of the impacts of climate change on early survivorship and the persistence of coastal invertebrate species.