My research in community ecology has been in two general areas: the role of disturbance in structuring natural communities and the ecology of host-parasite interactions.
Mangrove forest dynamics: My current research examines the role of lightning-generated canopy gaps in the regeneration of mangrove forests on the Caribbean coast of Panama. We are investigating with sampling and experimental studies a variety of biotic and abiotic factors that could account for spatial and temporal variation in patterns of gap regeneration. Such factors include propagule dispersal, competition among seedlings and saplings for light and nutrients, and herbivory by crabs and insects.
Estuarine host-parasite interactions: For about 10 years, I studied the interactions between the salt marsh snail Cerithidea californica and a diverse assemblage of larval trematodes that exploit it as first intermediate host in their life cycles. The two major questions this research addressed were (1) do parasites compete for snail hosts?, and (2) do parasites regulate snail population size?
Disturbance and succession in rocky seashore communities: My dissertation work demonstrated that intermediate levels of disturbance could maintain the diversity of intertidal algal assemblages, and tested several alternative models of succession. Later, I studied the effects of disturbance patch size and its interaction with herbivory on successional dynamics within intertidal mussel beds.
Sousa, W.P., S.P. Quek, and B.J. Mitchell. 2003. Regeneration of Rhizophora mangle in a Caribbean mangrove forest: interacting effects of canopy disturbance and a stem-boring beetle. Oecologia 137:436-445.
Sousa, W.P., P.G. Kennedy, and B.J. Mitchell. 2003. Propagule size and predispersal damage by insects affect establishment and early growth of mangrove seedlings. Oecologia 135:564-575.
Sousa, W.P. 2001. Natural disturbance and the dynamics of marine benthic communities. In Marine Community Ecology, ed. M.D. Bertness, S. D. Gaines, and M.E. Hay, 85-130. Sinauer Assoc., Sunderland, MA.
Sousa, W.P. and B.J. Mitchell. 1999. The effect of seed predators on plant distributions: is there a general pattern in mangroves? Oikos 86:55-66.
Sousa, W.P. 1993. Interspecific antagonism and species coexistence in a diverse guild of larval trematode parasites. Ecol. Monogr. 63:103-128.
Sousa, W.P. 1984. Intertidal mosaics: patch size, propagule availability, and spatially variable patterns of succession. Ecology 65:1918-1935.