2022 Volume 17 Issue 2 Pages 137-146
Mytilopsis sallei (Récluz, 1849), an invasive bivalve, has been established for more than two decades in Pawong Canal, which is a part of the largest lagoon system in Thailand. A recent survey in 2019 revealed the presence in the canal of another invasive species, the mytilid mussel Mytella strigata (Hanley, 1843). Both species are byssally attached bivalves that can change soft bottoms into hard substrata composed of bivalve shells, with consequent effects on benthic communities. Data of benthic macro-invertebrate species collected 25 years ago, before the arrival of both invasive species, were compared with data from a recent survey. Although 28 different species were observed in each study, only five were present in both. However, there is no significant change in the diversity and evenness of this benthic community. A few species of hard-bottom dwellers appeared in the canal after invasion while some soft-sediment inhabitants were absent. Given that the full dataset from the previous study was not available and a long-term series of observations was not made, it is difficult to distinguish the effects of bivalve invasion from the effects of physical change in the environment. However, we documented the current condition of this complex estuarine ecosystem and discussed some possible effects of non-native bivalve invasion on the local benthic macroinvertebrate assemblages.
