Comparative population biology and reproduction of two sympatric crabs (Grapsidae) on Azores cobble beaches |
| |
Authors: | Tarso De Menezes Macedo Costa Nuno Miguel da Silva Ascensão Vaz Álvaro Armindo Dos Santos Rodrigues Ana Isabel De Melo Azevedo Neto José Manuel Viegas Oliveira Neto Azevedo |
| |
Affiliation: | 1. cE3c/ABG ? Centre for Ecology, Evolution and Environmental Changes/Azorean Biodiversity Group, and University of Azores, Faculty of Sciences and Technology, Ponta Delgada, Portugaltarso.mm.costa@uac.pt;3. IITAA - Institute for Research and Technology of Agronomy and Environment, Climate Environment and Landscape Group, Universidade dos A?ores, Angra do Heroísmo, Portugal;4. Faculty of Sciences and Technology and IVAR, Institute of Volcanology and Risks Assessment, University of the Azores, Ponta Delgada, Portugal;5. cE3c/ABG ? Centre for Ecology, Evolution and Environmental Changes/Azorean Biodiversity Group, and University of Azores, Faculty of Sciences and Technology, Ponta Delgada, Portugal |
| |
Abstract: | Population biology of the intertidal crabs Pachygrapsus marmoratus Fabricius, 1787 and P. maurus (Lucas 1846) was investigated at cobble beaches with different levels of wave exposure. Surveys were taken monthly over 1.5 years at three intertidal levels. The growth rate of both species was similar, although P. marmoratus reached larger sizes. This species was more abundant on the mid-littoral zone of sheltered beaches, whereas P. maurus was more abundant on more exposed ones. The sex ratio was male biased in both species, particularly for the smaller and larger size classes. Both species showed an extended reproductive season, coinciding with the rising temperatures of spring and summer, with ovigerous females being found from June to September for P. marmoratus and from May to August for P. maurus. The present study indicates that both could develop adaptive strategies allowing them to coexist in the Azores littoral. The greater size of P. marmoratus seems to be an advantage on the competition for refuges with P. maurus, which results in its higher abundance and general dominance in the higher shore levels and in less exposed shores. However, P. maurus seems to be more fitted to live in the higher hydrodynamic habitats. |
| |
Keywords: | Population biology mottled shore crabs animal reproduction sex ratio age and growth |
|
|