Marine invasion history and vector analysis of California: a hotspot for western North America

Abstract

Aim We examine the regional dominance of California as a beachhead for marine biological invasions in western North America and assess the relative contribution of different transfer mechanisms to invasions over time. Location Western North America (California to Alaska, excluding Mexico). Methods We undertook extensive analysis of literature and collections records to characterize the invasion history of non‐native species (invertebrates, microalgae and microorganisms) with established populations in coastal marine (tidal) waters of western North America through 2006. Using these data, we estimated (1) the proportion of first regional records of non‐native species that occurred in California and (2) the relative contribution of transfer mechanisms to California invasions (or vector strength) over time. Results Excluding vascular plants and vertebrates, we identified 290 non‐native marine species with established populations in western North America, and 79% had first regional records from California. Many (40–64%) of the non‐native species in adjacent states and provinces were first reported in California, suggesting northward spread. California also drives the increasing regional rate of detected invasions. Of 257 non‐native species established in California, 59% had first regional records in San Francisco Bay; 57% are known from multiple estuaries, suggesting secondary spread; and a majority were attributed to vessels (ballast water or hull fouling) or oysters, in some combination, but their relative contributions are not clear. For California, more than one vector was possible for 56% of species, and the potential contribution of ballast water, hull fouling and live trade increased over time, unlike other vectors. Main conclusions California, especially San Francisco Bay, plays a pivotal role for marine invasion dynamics for western North America, providing an entry point from which many species spread. This pattern is associated historically with high propagule supply and salinity. Any effective strategies to minimize new invasions throughout this region must (1) focus attention on California and (2) address current uncertainty and future shifts in vector strength.

The non-indigenous Paranthura japonica Richardson, 1909 (Isopoda: Anthuroidea: Paranthuridae) from the Mar Piccolo lagoon, Taranto (Italy, Mediterranean Sea)

“…japonica has its native range in the Asian Western Pacific (Lee II and Reusser 2012), but it is spreading to other regions assumably as a result of human-mediated introductions (Ruiz et al 2011;Lavesque et al 2013;Marchini et al 2014). In particular, the species was recorded from San Francisco Bay in 1993, initially as Paranthura sp.…”

Early phase of the invasion of Balanus glandula along the coast of Eastern Hokkaido: changes in abundance, distribution, and recruitment

“…Even a few such successful and growing populations may contribute greatly to range expansion. The supply of larvae from a hotspot, a small portion of the locations with remarkably high abundance, plays an important role in range expansion (Semmens et al 2004;Leslie et al 2005;Ruiz et al 2011). Indeed, the temporal pattern in the coverage at A1 was similar to that of the mean population coverage.…”

Revisiting recent history: records of occurrence and expansion of the European green crab across Prince Edward Island, Atlantic Canada

“…The importance of larvae and larval behaviour during the invasion of a new region cannot be disregarded (Cohen and Carlton 1998;Daigle et al 2016). However, secondary dispersal by benthic stages may be as important (Ruiz et al 2011) during local-scale movements among neighboring water bodies. Juveniles and adults frequently hitchhike on recreational boats or fishing gear (Minchin 2007) and, in fact, hitchhiking by green crabs has been reported in the Gulf of St. Lawrence (Darbyson et al 2009).…”