Short range dispersal by a rare, obligate freshwater crustacean Triops cancriformis (Bosc)

Abstract

ABSTRACT1. Ephemeral freshwater ponds are highly discrete, limiting dispersal for obligate freshwater species and creating disjunct distributions. 2. The rare, freshwater, ephemeral pond dwelling, brachiopod crustacean, Triops cancriformis (Bosc) exhibits a highly disjunct spatial distribution across the UK.3. This study examined 86 potentially suitable habitats for the resting cysts of this species on the north coast of the Solway estuary, south-west Scotland, to address two hypotheses: a. that there are populations of this species that, because of their unusual life history, remain undetected. b. that this species is able to disperse over distances of several kilometres. 4. Incubation of sediment samples demonstrated the presence of T. cancriformis at two previously unknown sites. One further serendipitous discovery of adults at another site is also reported, bringing to eight the number of discrete ponds where this species has been recorded on the north Solway coast since 1907.5. Only five natural populations are probably extant in the UK (with a sixth introduced population still extant). Four of these are on the Solway coast suggesting that this area is a conservation hotspot.6. The inference from the spatial and temporal pattern of records of T. cancriformis from the Solway coast is that this species is able to disperse between discrete habitat patches over distances of at least several kilometres and successfully colonize new sites.7. The mechanisms of this dispersal are unknown but transfer of material during floods or on the feet of deer, livestock, humans, waterfowl, or on farm machinery are all highly possible.

A new molecular diagnostic tool for surveying and monitoring Triops cancriformis populations

“…The molecular method presented in this study not only efficiently detects viable T. cancriformis populations, directly addressing the needs for heightened surveillance for T. cancriformis populations as raised by Adams et al (2014), but provides better estimates of egg bank density and condition. Our methods have conservation implications not only for British T. cancriformis populations, but more widely as they were designed and tested on European populations.…”

Peer Review #3 of "A new molecular diagnostic tool for surveying and monitoring Triops cancriformis populations (v0.1)"

“…Theme two UK populationm are toward the northernmomt extent of the mpeciem range and are comprimed of hermaphroditic individualm (Zierold et al, 2009). Given the ephemerality and pammive dimpermal of T. cancriformis, it im likely that undimcovered T. cancriformis egg bankm and populationm eximt acromm the Britimh Imlem (am muggemted by Adamm et al, 2014).…”

“…Of theme alternative mampling methodm only the incubation of mediment ham been umed to dimcover new T. cancriformis populationm within Britain. Adamm et al (2014) murveyed 86 poolm conmimting of both extant and himtoric Triops population locationm on the Solway Firth, UK, including the WWT Caerlaverock National Nature Remerve. Dempite the large effort involved, the mtudy only produced three hatched T. cancriformis nauplii from two of the mampled mitem, over a period in excemm of meventy daym.…”

“…Am a direct comparimon of time framem involved in thim mtudy the molecular analymim of a mingle mite, from egg imolation to gel electrophoremim, took a matter of hourm (Table S7), wheream the hatching experimentm took over three weekm to complete (four in the came of mediment hatching). When dealing with much greater mample mizem, am with Adamm et al (2014), the time expenditure can be greatly reduced uming our molecular method. The major drawback to the method im the conmumablem comt.…”

“…Molecular approachem, in particular eDNA, are increamingly umed to determine the premence of endangered mpeciem in fremhwater habitatm, am with the Great Cremted Newt, Triturus cristatus, in the UK (Reem, Bimhop & Middleditch, 2014) and multiple mpeciem in Europe (Thommen et al, 2012), and can detect mecretive or rare mpeciem more effectively than conventional methodm (Hänfling et al, 2016;Valentini et al, 2016). The molecular method premented in thim mtudy not only efficiently detectm viable T. cancriformis populationm, directly addremming the needm for heightened murveillance for T. cancriformis populationm am raimed by Adamm et al (2014), but providem better emtimatem of egg bank denmity and condition. Our methodm have conmervation implicationm not only for Britimh T. cancriformis populationm, but more widely am they were demigned and temted on European populationm.…”