Autor(es):
Bessa, Filipa 
; Baeta, Alexandra ; Marques, João Carlos
Data: 2014
Identificador Persistente: http://hdl.handle.net/10316/24943
Origem: Estudo Geral - Universidade de Coimbra
Assunto(s): Sandy beach; Primary consumers; Peracarid crustaceans; Diet; Stable isotopes; Niche segregation
Descrição
Wrack supplies (macroalgae, seagrasses and carrion) are a common feature of sandy beaches worldwide.
These allochthonous inputs are a potential high-quality food subsidy for beach fauna, but little is known
about the feeding ecology and niche segregation strategies of these species in beaches with limited wrack
availabilities. We used stable isotopic ratios of nitrogen and carbon to examine the diets and niche segregation
among three sympatric crustaceans, the amphipods Talitrus saltator and Talorchestia brito, and
the isopod Tylos europaeus, in two temperate beaches, Cabedelo and Quiaios, on the Portuguese Atlantic
coast, with contrasting wrack availabilities, over winter and summer. In the beach with limited wrack
(Quiaios), consumers showed significantly different interspecific and temporal isotopic signatures, suggesting
a distinct foraging habitat and niche differentiation. Mixing models outputs (SIAR) revealed in
this case a seasonal shift in the diet of consumers from terrestrial sources in winter towards marinebased
sources (phytoplankton) in the summer. In contrast, at Cabedelo, consumers showed clear overlap
in isotopic signatures, with similar contributions of the available wrack to their diets. As a whole, an
opportunistic and generalist feeding behaviour was described for these species, namely for T. saltator.
Isotopic profiles support the occurrence of spatial overlap during summer but different foraging strategies
of the three species in these beaches during winter. Our results show that on temperate beaches with
ephemeral wrack supplies, consumers might need to adopt different foraging strategies and niche segregation
for their subsistence, and additionally illustrate the viability of using stable isotopes to capture
subtle changes in trophic niches. AcknowledgementsThis research was supported by FCT (Fundac¸ ão para a Ciência eTecnologia) in the scope of the Project PEst-C/MAR/UI0284/2011and through a PhD Grant awarded to Ana Filipa Bessa(SFRH/BD/64929/2009).
