Two alien species of Branchiobdellida (Annelida: Clitellata) new to the British Isles: a morphological and molecular study

Abstract

Taking into account the continuous increase in freshwater introductions, and to support the recent European legislation on invasive alien species, the identification of priority pathways and gateways of introductions is of utmost importance to develop adequate control strategies. The aim of this paper was to analyse the main pathways and gateways of introductions of freshwater alien species in Europe. Based on a thorough review of the scientific and grey literature, information on pathways, country and year of initial introduction of all freshwater alien species in Europe, was retrieved. The spatial and temporal patterns and trends of biological invasions in freshwater ecosystems in Europe, in relation to different pathways, were assessed. Our results pinpoint the major importance of aquaculture, pet/aquarium trade and stocking activities as pathways of introduction of freshwater alien species in Europe. For species native to some European countries, shipping and inland canals were the most important pathways, highly responsible for the entry of many harmful species. Germany, the United Kingdom and Italy were the main entry gateways of freshwater alien species in Europe. We found a geographical pattern related to some pathways of introduction in Europe: introductions through inland canals were concentrated in Central/North-eastern Europe, while introductions through pet/terrarium/aquarium trade were mainly observed in Central/Western Europe. While Chordata species entered Europe mainly through the three major above mentioned pathways, many harmful Arthropoda and Mollusca entered through shipping and inland canals. The information gathered in this study clearly indicates the entry routes that should be prioritised by Member States, for which stronger control and management actions should be implemented and prevention efforts concentrated under the scope of the related new EU Regulation.

Assessing the invasion potential of non-native branchiobdellidans: experimental studies of survival, reproduction and competition

“…C. aff. okadai is less abundant than X. victoriensis in the Welsh population (James et al, 2015a) and more difficult to maintain in the lab, and therefore could not be tested under all experimental conditions.…”

“…Infection intensities represented those naturally present in the field, based on crayfish size category (carapace length, mm): 28-31; 32-35; 36-39; 40-43; 44-48 infected with 21, 28, 65, 101 and 154 worms respectively (James et al, 2015a). Host crayfish were maintained individually in aerated 15 L plastic tanks with a plastic refuge.…”

“…Signal crayfish harbouring branchiobdellidans (X. victoriensis and C. aff. okadai identified according to James et al (2015a) were collected from the River Gavenny (SO308164), South Wales.…”

“…okadai and Xironogiton victoriensis, were recently found for the first time on invasive signal crayfish (Pacifastacus leniusculus) in the UK (James et al, 2015a). Signal crayfish are widespread across the UK , and have altered the structure and function of recipient ecosystems throughout their non-native range (James et al, 2015c).…”

“…Given the high frequency of co-infection between C. aff. okadai and X. victoriensis (see James et al, 2015a), intraguild competition and predation may also predict the likelihood of either species persisting.…”