Could artificial structures such as fish passes facilitate the establishment and spread of the ‘killer shrimp’ Dikerogammarus villosus (Crustacea: Amphipoda) in river systems?

Abstract

ABSTRACT1. Linkages between habitat structure, invasibility and direct species interactions were examined in a Central European river system, the Schipbeek in the Netherlands, invaded by the 'killer shrimp' amphipod Dikerogammarus villosus. The invader's arrival in other fresh waters is linked to declines in macroinvertebrate biodiversity, with previous studies indicating that the invader's impacts may be mediated by habitat heterogeneity and substrate type.2. Using an extensive 50 km field survey, potential habitat factors influencing distribution were identified. Of 12 sites surveyed, two contained fish 'passes' (instream sections creating faster flows via concrete structures covered in cemented rocks). It was only in these sites that D. villosus was found and then only in the fish pass areas, as opposed to the surrounding river, which, like the remaining 10 sites of the survey, was characterized by sluggish flows and a muddy/silty substrate. Gammarus roeselii was the numerically dominant amphipod in these latter areas, with no D. villosus being detected. A repeated survey more than 2 years later, revealed the same distribution pattern.3. Within both fish pass areas, D. villosus relative abundance was highest in faster flowing, less macrophyte dense patches, with the opposite true for G. roeselii. D. villosus numerical abundance decreased with increasing macrophyte cover in both passes.4. A transplant experiment indicated high survivorship of D. villosus outside fish pass areas and showed that slow-flowing watercourses with mud/silt substrates, previously deemed 'unsuitable', are not effective barriers to D. villosus spreading to more 'suitable', faster, rocky substrate watercourses.5. We recommend that when the location and cost-benefit analysis of instream rehabilitation structures, such as fish passes, is being considered, attention must be paid to the risk of hastening the spread of this invader. We also recommend that when monitoring programmes are designed for D. villosus in newly invaded regions, instream artificial structures should be included as part of the survey.

Current velocity shapes co‐existence patterns among invasive Dikerogammarus species

“…Our results suggest that the apparently different invasion success of the species corresponds to their position on the stress tolerance–competitive ability axis, implying that the advantage of D. villosus is attributable to its competitive dominance, allowing it to monopolize lentic and/or structured habitats, which represents a fortunate pre‐adaptation to anthropogenic alterations of waters; i.e. ripraps, impoundments and fish passes (MacNeil & Platvoet, ). The presence of D. villosus does not greatly impede the expansion of D. haemobaphes ; however, it can be expected to reach high densities only in rivers and only if the food supply is favourable.…”

“…Previous observations on the flow preferences of the species are scarce, especially for D. haemobaphes and D. bispinosus ; nevertheless, the primary role of current velocity is in concert with the longitudinal distribution of the species in the River Dniester, where the abundance of D. bispinosus decreased downstream , D. haemobaphes was the most widespread and D. villosus was found only in the lagoon, where D. bispinosus was missing (Jażdżewski & Konopacka, ). Field studies involving D. villosus reflect strong context dependency, their conclusions including preference for lentic conditions (Boets et al ., ), relative indifference (Devin et al ., ) and affinity to flow‐exposed, but strongly structured, habitats (MacNeil & Platvoet, ); whereas the only flume experiment involving the species demonstrated that it avoids strong currents by using flow refuges (Felten, Dolédec & Statzner, ). Our results confirm that the species is primarily rheophobic, but it can utilize lentic microhabitats offered by obstacles in the water (i.e.…”

Substrate preferences of coexisting invasive amphipods, Dikerogammarus villosus and Dikerogammarus haemobaphes, under field and laboratory conditions

“…In areas of relatively simple habitat/substratum complexity, native amphipods may be more vulnerable to the effects of invader niche overlap, potentially leading to regional extinctions of native taxa (MacNeil et al 2010). Habitat homogenisation and anthropogenic modifications may even enhance the successful colonisation and future expansion of populations of invasive taxa (Johnson et al 2008;MacNeil and Platvoet 2013).…”

Experimental evaluation of preferences of an invasive Ponto-Caspian gammarid Pontogammarus robustoides (Amphipoda, Gammaroidea) for mineral and plant substrata

“…One of the most important factors determining the quality of a habitat is its complexity, which affects the structure of biological communities (Murdoch & Oaten, 1975;Holt, 1984;Kovalenko et al, 2012) and relationships between organisms belonging to different trophic levels (Briand & Cohen, 1987;Whitehead & Walde, 1992) by changing their susceptibility to predators, competitive interactions and feeding (Engström-Ö st et al, 2006). In particular, habitat fragmentation can produce edge effects promoting competition or predation (MacNeil & Platvoet, 2013).…”