Invasive Asian clam distribution pattern reveals minimal constraints to downstream dispersal and imperceptible ecological impacts

Abstract

1. The Asian clam Corbicula fluminea is an invasive freshwater species that can cause adverse ecological and economic impacts. Information on its dispersal abilities, ecological preferences and impacts may contribute towards the improvement of management strategies, including those relating to regulatory demands such as the European Water Framework Directive (WFD).2. Both the above perspectives were addressed through inspection of environmental constraints to C. fluminea dispersal and impacts in a semi-natural drainage catchment (interconnected system of ditches). Forty sites were surveyed in 2014 to describe the species distribution and to characterize benthic macroinvertebrate communities, water column and sediment physico-chemistry, as well as the hydromorphological conditions. 3. Clams were unevenly distributed in the study area and artificial barriers (dikes) did not prevent downstream dispersal of juveniles. Large variation in clam density (0-3077 clams m −2 ) could not be explained by physico-chemical or hydromorphological gradients. Although typical clam preference ranges reported in the literature were often exceeded, dense populations were nevertheless observed. 4. Macroinvertebrate community structure suggested associations between the Asian clam and some functional feeding groups. However, the impacts of clams on macroinvertebrate assemblages and ecological quality were negligible, suggesting that contemporary methods designed to comply with the WFD bioassessment scheme may fail to detect important drivers of ecological change in freshwater ecosystems.5. This study demonstrated the reduced ecological impacts and broad ecological competence of the Asian clam, but also that its spread depends on human vectors. These findings highlight the need to rethink prediction tools supporting preventive measures against the introduction and spread of this invasive bivalve.

The role of temperature and oxygen availability on the distribution ofCorbicula largillierti

“…Our results are consistent with the latest study of Pereira et al. (2017), which suggests that sediment characteristics are weaker predictors of corbiculid distribution per se.…”

“…In fact, it has been assumed that the presence of C. fluminea on higher grain size sediments is indeed related to the degree of oxygenation, which is always higher in coarse sediments (Castañeda et al, 2018;McMahon, 1999). Our results are consistent with the latest study of Pereira et al (2017), which suggests that sediment characteristics are weaker predictors of corbiculid distribution per se.…”

“…Temperature and environmental oxygen concentration ( p O 2 ) are among the most important factors that determine bivalve distribution (Castañeda et al., 2018; Gama et al., 2017; Le Moullac et al., 2007; Pereira et al., 2017; Reyna et al., 2018; Schmidlin & Baur, 2007). Temperature determines, to a large degree, the metabolic rate of organisms.…”

Corbicula incorporation to indicator parameters to assess the ecological status of northwestern Iberian estuaries

“…In one side, Selego et al (2012) also reported collector-gatherers replacement by collectorfilterers after river restoration efforts. In contrast, Pereira et al (2017) reported an apparent association between both functional feeding groups. Hence, conclusions in this regard would be speculative and further manipulative work may be needed to clarify functional feeding groups association.…”

Critical reduction of the geographic distribution of Cyanocyclas (Cyrenidae: Bivalvia) in Uruguay

“…The published literature on competition between native bivalves (mainly the Unionoida) and Corbicula is extensive, but conclusions regarding the effects of this interaction are often different (Miller & Payne, ; Vaughn & Spooner, , and references therein). Similarly, although Corbicula has been traditionally regarded as posing a serious threat to native biodiversity and ecosystem functioning, with possible environmental and economic repercussions (Sousa, Rufino, Gaspar, Antunes, & Guilhermino, ), recent research also suggests negligible ecological impacts (Pereira et al, ). In this vein, Corbicula and Cyanocyclas do coexist at present in four out of the five remaining local populations.…”