Functioning of coastal food webs : intertidal rock pools as a case-study

Mendonça, Vanessa

http://hdl.handle.net/10451/43870

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Authors

Mendonça, Vanessa

Advisor(s)

Vinagre, Catarina

Flores, Augusto

Abstract(s)

Rocky intertidal ecosystems have long attracted the attention of biologists, being viewed as natural laboratories, where biodiversity and species-interactions could be easily investigated. However, intertidal rock pools have received much less attention that the surrounding emergent intertidal platforms. The aim of this thesis was to provide new insights into the trophic ecology of intertidal rock pools through 1) the characterization of pools as proxies for the study of ma-rine food web networks; 2) the investigation of food web network robustness to species loss in temperate and tropical ecosystems; 3) the investigation of food web robustness to heat-waves in temperate and tropical ecosystems; 4) the description of seasonality in the food web net-works; and 5) the testing of the role of pools as preferential feeding grounds for transient fish species. It was concluded that intertidal rock pools can be used as proxies for the study of marine food web networks. Tropical food webs revealed higher robustness than temperate food webs, however the tropical food webs’ topology suffered more alterations after species loss. Food web networks presented similar robustness to the removal of species based on thermal vulnerability, however the tropical webs encompass more thermally vulnerable species and should, thus, suffer more species loss in a heat-wave context. The basic topology of temperate webs was stable throughout the year. Intertidal rock pools are likely used as preferential feeding grounds by early-stages of transient fish, as showed by the consistent similarity between stom-ach contents and prey availability inside the pool, observed for all species. Overall, this work opens a brand-new research avenue with the use of intertidal rock pools as proxies for the study of marine food web networks, while also shedding light into the particular vulnerability of tropical food webs and the important role of pools in fish early-life.