Time‐series analysis of native and non‐native crayfish dynamics in the Thames River Basin (south‐eastern England)

Abstract

1. Monitoring is crucial for the conservation of endangered crayfish species as well as for managing and controlling invasive species. Yet, relatively few studies have assessed relationships between native white-clawed crayfish Austropotamobius pallipes and non-native signal Pacifastacus leniusculus, narrow-clawed Astacus leptodactylus, virile Orconectes virilis and red-swamp Procambarus clarkii crayfishes in freshwater environments at ecologically relevant spatial and temporal scales.2. Thus, the present study examines the distribution dynamics of native and non-native crayfishes in the River Thames Basin District (16 133 km 2 , south-eastern England) over four decades .3. To reveal geographical bioinvasion and decline patterns, data on occurrences (sampling site, date) of native white-clawed and four non-native crayfishes were used to create sequences of decade maps for each species. Cumulative numbers of occupied grid squares were used to construct 'invasion/decline' curves and rates. To quantify dynamic features, the frequencies of survey occurrence for each species were subjected to time-series analysis, followed by cross-correlation to determine relationships between crayfishes.4. White-clawed crayfish was initially widespread, but gradually disappeared after the mid-1970s, coinciding with the introduction and initial dispersal of signal crayfish. During 2001-2010 white-clawed crayfish numbers declined steeply. Introduced in the mid-1980s, narrow-clawed crayfish spread within a few years, but is now restricted to the east of the basin, where virile and red-swamp crayfishes were reported with low presence since their introductions in 2006. Dynamics of white-clawed and signal crayfishes showed the opposing trends with a highly significant negative association.5. Geographical patterns indicate that non-native crayfishes were introduced in multiple locations in the study area. Recovery of native crayfish seems unlikely, given the impacts of signal crayfish and the continuing arrival of new crayfish species. This paper demonstrates the utility of using broad temporal and spatial scales for revealing accurate insights on invasion and decline dynamics.

Continental-wide distribution of crayfish species in Europe: update and maps

“…Recently, self-sustaining population of white river crayfish was found also in southeastern England (Reading, Berkshire; Almeida et al, 2013). Besides these two recently established populations, introduction of white river crayfish from Louisiana to Spain along with P. clarkii in the 1970s was also suggested (Habsburgo-Lorena, 1979;Henttonen and Huner, 1999).…”

“…Dark grey cells indicate changes since . Updates since are based on Janský and Mutkovič (2010); Benejam et al (2011);Jaklič and Vrezec (2011);Almeida et al (2013); Bohman et al (2013);S. Bertocchi (unpubl.…”

Indicators of movement and space use for two co-occurring invasive crayfish species

“…Several authors studied the progression of the invasion front or the movement patterns of each of these species (e.g. Bubb et al, 2004;Aquiloni et al, 2005;Kerby et al, 2005;Bernardo et al, 2011;Almeida et al, 2013;Johnson et al, 2014) but not the coexistence of the two species. P. clarkii and P. leniusculus have distinct but nevertheless overlapping environmental niches .…”

Historical data reveal fish assemblage shifts in an unregulated prairie river

“…In addition, there is evidence that sand shiners Notropis stramineus have substantially increased in abundance in the Powder River (Patton 1997). Historical data provides a unique opportunity to evaluate shifts in assemblage composition through time (Patton et al 1998, Almeida et al 2014. We used historical and contemporary fish sampling data to examine assemblage composition in the mainstem Powder River over the period of fish sampling records.…”