Browsing by Author "Ilarri, Martina"
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- Interspecific differences in the physiological condition of native freshwater mussels in response to the invasive Asian clam Corbicula flumineaPublication . Modesto, Vanessa; Ilarri, Martina; Castro, Paulo S.; Carvalho, Francisco; Cavalheri, Thais; Lopes-Lima, Manuel; Teixeira, Amílcar; Ozório, Rodrigo O.A.; Antunes, Carlos; Sousa, RonaldoThe Asian clam Corbicula fluminea has been widely introduced into aquatic ecosystems and may impact the physiological condition and survival of native freshwater mussels. However, very few studies have evaluated this issue quantitatively. To fill this gap, manipulative field experiments were performed to assess two possible mechanisms of impact on native mussels: (i) interspecific interactions, and (ii) C. fluminea die-offs. We assessed these effects by measuring the physiological condition through the analysis of glycogen content in the foot tissue of the native freshwater mussel species Anodonta anatina, Potomida littoralis, and Unio delphinus. Although with interspecific differences, our results suggest that C. fluminea can impact the physiological condition of native freshwater mussels. Anodonta anatina showed positive significant variations on glycogen content when subjected to high densities of live C. fluminea in contrast to the other native species studied, P. littoralis and U. delphinus, where no significances were observed. On the other hand, these native species do not seem be significantly impacted by the decomposition of C. fluminea resulting from a die-off. Overall, and contrary to our expectations, both experiments showed a positive (or no) effect of C. fluminea on the physiological condition of the three freshwater mussel species.
- Trophic niche overlap between native bivalves and the invasive Corbicula flumineaPublication . Modesto, Vanessa; Dias, Ester; Lopes-Lima, Manuel; Teixeira, Amílcar; Varandas, Simone; Antunes, Carlos; Guilhermino, Lúcia; Ilarri, Martina; Sousa, RonaldoFreshwater native bivalves have declined in recent decades and are considered one of the most threatened faunistic groups worldwide. Many mechanisms can be responsible for this declining trend, being competition for resources with invasive bivalve species one example. When in sympatry with native species, invasive bivalves may be superior competitors regarding food acquisition due to more flexible diets, higher abüity to find food resources or use it with higher efficiency. However, their potential for food competition is poorly known. In this study, we aimed to evaluate the potential overlap in resource use by bivalve species (native and invasive) living in sympatry in the Tua basin (NW-Iberian Península), by identiíying and quantifying the contribution of different organic matter (OM) sources to their biomass. To accomplish this objective, the C (ÕiaC: "C/i^C) and N (Ô"N: "N/xN) stable isotope ratios of bivalves and its potential OM sources were analyzed. Special attention was given to the possible overlap between native bivalve species Anodonta anatina, Unio delphinus and Potomida littoralis, and one of the most pervasive invasive species in European aquatic ecosystems, the Asian ciam Corbicula fluminea. The stable isotope analysis suggests that C. fluminea and P. littoralis rely on "C- and "N- enriched sources such as microphytobenthos or other microbial enriched material and that the potential for resource competition is high because their trophic niche overlaps. Contrarily, the potential for competition with A. anaüna and U. delphinus is likely lower because both native species were in general more "C- and isN- depleted than C. fluminea indicating the consumption of more i3C- and "N- depleted food sources such as pelagic OM.
- Trophic niche overlap between native freshwater mussels (Order: Unionida) and the invasive Corbicula flumineaPublication . Modesto, Vanessa; Dias, Ester; Ilarri, Martina; Lopes-Lima, Manuel; Teixeira, Amílcar; Varandas, Simone; Castro, Paulo S.; Antunes, Carlos; Sousa, RonaldoFreshwater mussels (Order Unionida) are highly threatened. Interspecific competition for food sources with invasive alien species is considered to be one of the factors responsible for their decline because successful invaders are expected to have wider trophic niches and more flexible feeding strategies than their native counterparts. In this study, carbon (δ13C: 13C/12C) and nitrogen (δ15N: 15N/14N) stable isotopes were used to investigate the trophic niche overlap between the native freshwater mussel species, Anodonta anatina, Potomida littoralis, and Unio delphinus, and the invasive bivalve Corbicula fluminea living in sympatry in the Tua basin (south-west Europe). The species presenting the widest trophic niches were C. fluminea and A. anatina, which indicate that they have broader diets than U. delphinus and P. littoralis. Nonetheless, all the species assimilated microphytobenthos, sediment organic matter, and detritus derived from vascular plants, although with interspecific variability in the assimilated proportions of each source. The trophic niche of the invasive species overlapped with the trophic niche of all the native species, with the extent varying between sites and according to the species. From the three native species analysed, Potomida littoralis may be at a higher risk for competition for food with C. fluminea in the Tua basin, if food sources become limited, because this native mussel presented the narrowest trophic niche across sites and the highest probability of overlapping with the trophic niche of C. fluminea. Given the global widespread distribution of C. fluminea, the implementation of management measures devoted to the control or even eradication of this invasive alien species should be a conservation priority given its potential for competition with highly threatened native freshwater mussels.