The biology and anatomy of Limnoperna fortunei, a significant freshwater bioinvader: Blueprints for success

Abstract

Limnoperna fortunei first came to scientific attention when it was introduced into the potable freshwater supply system of Hong Kong around 1968. The initial occurrence in Hong Kong was related to the commencement of supplies of water from the East River in China. Aspects of the biology and anatomy of L. fortunei were investigated in 1973 (Morton, Malacologia 12:265-281, 1973). Then, comparisons were made with other mytiloids and with the invasive Dreissena polymorpha (Dreissenidae), which L. fortunei resembles superficially. The suggestion of a relationship between the two taxa was discounted on anatomical grounds- both species being convergently heteromyarian, adapting them to similar lives in the freshwater habitats of Eastern and, subsequently, Western Europe and North America, and mainland Asia plus Japan and Taiwan and latterly South America, respectively. The present study re-examines aspects of the biology and anatomy of L. fortunei commensurate upon its recent range extensions, specifically with regard to its occupation of a variety of freshwater habitats in order to better understand the reasons for its opportunistic success. It is concluded that L. fortunei probably evolved from a brackish water either Xenostrobus-like or Perna-like ancestor-the question of Limnoperna’s ancestry still unresolved. Regardless, it was the evolution of the heteromyarian form in the, indisputedly mytiloidean, ancestor that opened up the hitherto bivalve-unoccupied hard-surface epibenthic environment for colonisation in both lentic and lotic freshwaters ecosystems. This was probably associated with the adoption of osmoregulation and efficient systems for the collection, selection and digestion of ample seston resources. The energy thereby obtained has been focussed into rapid fecundity at the expense of shell growth and the adoption, thereby, of a r-selected sexual strategy and life history trait.