The burrowing rate index

Brown, Autumn; Trueman, E. R.

doi:10.1093/mollus/60.3.354

Cited by 6 publications

(1 citation statement)

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“…On the other hand, male natural mortality did not support the SEH either. High rates of male mortality at the dissipative beach could be explained by size-dependent predation effects by birds, gastropods, crabs, fishes and insects, which are by far more abundant at dissipative beaches (Griffiths et al 1983, Brown & McLachlan 1990, Colombini & Chelazzi 1996. Predation could act as the main selection pressure determining body size, and thus higher growth rates of females, postulated as dominant intra-specific competitors, should be directed to diminish predation risks.…”

Section: Reproduction Growth and Mortalitymentioning

confidence: 99%

Testing the swash exclusion hypothesis in sandy beach populations: the mole crab Emerita brasiliensis in Uruguay

Defeo¹,

Gómez²,

Lercari³

2001

Mar. Ecol. Prog. Ser.

116

102

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Exposed marine beaches are physically rigorous habitats in which macrofauna community patterns have been well correlated with physical factors such as grain size, beach slope and wave/swash processes. In this context, the swash exclusion hypothesis (SEH) gained wide acceptability in explaining the control of species abundance and diversity of the sandy beach macrofauna by swash climate, determined by wave height and beach face slope. This hypothesis predicts a consistent increase in species richness, abundance and biomass from reflective to dissipative conditions. However, predictions of the SEH have not been adequately tested at a population level. Here, demographic and life history characteristics of the intertidal mole crab Emerita brasiliensis were compared between populations of 2 microtidal exposed sandy beaches with contrasting morphodynamics during 22 consecutive months. The major prediction of the paradigm does not hold for the mole crab: total abundance, as well as that of males, females, males with spermatophores and megalops did not differ between beaches. Moreover, the reflective beach population presented higher male growth rates in size and lower natural mortality. Other population processes and life history traits gave support for the SEH: the dissipative beach population presented (1) higher abundance of ovigerous females, female growth rates, fecundity, egg production potential, size at maturity, as well as weight at size; and (2) lower female mortality and burrowing rates (for both sexes). The SEH seems to be particularly useful in explaining female somatic growth and reproductive features, which could be related to a major amount of food availability in dissipative beaches. However, other competing, but not exclusive, hypotheses are needed to explain variations in population abundance and other processes such as male growth and survivorship. The empirical evidence from several recent studies on the Uruguayan coast showed that sandy beach populations that co-occur in contrasting environments are less sensitive to variations in beach morphodynamics, which should not be considered the primary factor affecting the abundance and some life history traits. The importance of alternative population regulation processes and mechanisms are stressed.

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Section: Reproduction Growth and Mortalitymentioning

confidence: 99%