An Invasive Fish and the Time-Lagged Spread of Its Parasite across the Hawaiian Archipelago

Abstract

Efforts to limit the impact of invasive species are frustrated by the cryptogenic status of a large proportion of those species. Half a century ago, the state of Hawai'i introduced the Bluestripe Snapper, Lutjanus kasmira, to O'ahu for fisheries enhancement. Today, this species shares an intestinal nematode parasite, Spirocamallanus istiblenni, with native Hawaiian fishes, raising the possibility that the introduced fish carried a parasite that has since spread to naïve local hosts. Here, we employ a multidisciplinary approach, combining molecular, historical, and ecological data to confirm the alien status of S. istiblenni in Hawai'i. Using molecular sequence data we show that S. istiblenni from Hawai'i are genetically affiliated with source populations in French Polynesia, and not parasites at a geographically intermediate location in the Line Islands. S. istiblenni from Hawai'i are a genetic subset of the more diverse source populations, indicating a bottleneck at introduction. Ecological surveys indicate that the parasite has found suitable intermediate hosts in Hawai'i, which are required for the completion of its life cycle, and that the parasite is twice as prevalent in Hawaiian Bluestripe Snappers as in source populations. While the introduced snapper has spread across the entire 2600 km archipelago to Kure Atoll, the introduced parasite has spread only half that distance. However, the parasite faces no apparent impediments to invading the entire archipelago, with unknown implications for naïve indigenous Hawaiian fishes and the protected Papahānaumokuākea Marine National Monument.

A case of complete loss of gill parasites in the invasive cichlid Oreochromis mossambicus

“…This unique introduction could have been associated with a strong sampling effect, consistently reducing the probability of parasite transfer when compared to other regions where several host introductions are frequently reported (Froese and Pauly 2011; Electronic Supplemental Material 1). In addition, such founder events altering the genetic diversity in colonizing host populations can also impact the genetic diversity of their parasites (Blakeslee and Fowler 2012;Gaither et al 2013). Depauperate genetic diversity causing inbreeding depression could have interacted with Allee or stochastic demographic effects (Lande 1988) for driving a hypothetically small introduced parasite population toward extinction.…”

Large‐scale introduction of the Indo‐Pacific damselfish Abudefduf vaigiensis into Hawai'i promotes genetic swamping of the endemic congener A. abdominalis

“…In addition, Hawaiian A. vaigiensis has a higher genetic diversity than our samples from the native range, indicating that Hawaiian A. vaigiensis has not experienced a genetic bottleneck, a result found in other introduced fishes in Hawai'i (Gaither et al . , ). As mentioned previously, A. vaigiensis probably arrived by rafting with marine debris.…”

Parasites and marine invasions: Ecological and evolutionary perspectives

“…no spillover has occurred, see Section 3.5). This low number can at least partly result from uncertainties on the status of many invasive host (Carlton, 1996) and parasite (Gaither et al, 2013) species, because it is often not known whether they are introduced or not. This makes it often difficult to assess whether a parasite species is native, co-introduced or has already spilled over (see Section 3.5).…”

“…Identifying the native range of cryptogenic parasites (parasites whose origin is unknown) is especially challenging as their taxonomy is poorly resolved and fossil and historical records are scarce (Vignon and Sasal, 2010). However, the cryptogenic status of parasites can be determined by combining population genetics, phylogeography and ecological survey data (Blakeslee et al, 2008;Gaither et al, 2013). For example, by using this multidisciplinary approach, Gaither et al (2013) confirmed the invasive status of the nematode Spirocamallanus istiblenni in the Hawaiian archipelago where it was introduced with Bluestripe snappers (Lutjanus kasmira) from French Polynesia and now spills over to native hosts (Gaither et al, 2013).…”