Two new nonindigenous isopods in the Southwestern Atlantic: Simultaneous assessment of population status and shipping transport vector

Abstract

The Southwestern Atlantic is often perceived as remote region, yet it is not immune to biological invasions. Patchy information on historical community composition hinders our ability to identify introductions to coastal ecosystems in this region. Hull fouling is an under-managed shipping vector that likely continues to transport large numbers of marine species worldwide. The port of Mar del Plata is a comparatively well-studied shipping and commercial hub that may serve as an observatory to monitor new introductions to the Argentine coast. Following detection of nonindigenous isopods during preliminary port sampling in 2007-2008, we organized regular port surveys aimed at assessing the level of population establishment and evaluated hull fouling as a potential introduction vector in the Port of Mar del Plata. In 2011-2012, we conducted 12 monthly dive surveys of port isopod communities in combination with three opportunistic surveys (two in-water, one in dry-dock) of hull fouling communities attached to a domestic research vessel during consecutive port calls at its base in this port. Replicate biofouling samples from underwater dock structures and the vessel's hull were collected by scraping invertebrates in 20 × 20 cm quadrats (even surfaces) and 1000 cm 3 of biofouling organisms (uneven surfaces). Both in port-and hull-fouling communities, we discovered the presence of the nonindigenous isopods Dynamene edwardsi and Paracerceis sculpta. This report constitutes the first detection of these two global marine invaders in American and Argentine waters, respectively. They likely represent relatively recent introductions to this corner of the world's oceans, yet our data indicate that both species are currently well established in Mar del Plata. These results demonstrate (for the first time in the case of D. edwardsi) the potential for hull fouling to disperse both species, and raise a warning on their potential expansion to other Southwestern Atlantic ports and Antarctica in a near future. Research on the marine communities of the Southwestern Atlantic is pressingly needed to establish pre-invasion communities and detect new introductions. Simultaneous surveillance of ports (invasion hubs) and vessels (vectors) can effectively detect invaders and inform prevention efforts in this region.

Deep segregation in the open ocean: Macaronesia as an evolutionary hotspot for low dispersal marine invertebrates

“…Although the dispersal ability of Dynamene specimens is thought to be fairly constrained, juveniles can be transported somewhat far from their birthplace by factors such as rough weather (Holdich, 1968b(Holdich, , 1970(Holdich, , 1976. Moreover, it is well documented that isopods can also be dispersed passively away from the coast (Ingólfsson & Agnarsson, 2003;Thiel, 2002) through rafting on floating objects (usually detached macroalgae; Scheltema, 1986;Thiel & Gutow, 2005), via anthropogenic transfer (Kiessling, Gutow, & Thiel, 2015;Rumbold et al, 2018) or, more rarely, if specimens remain attached to other species (Sponer & Lessios 2009), including marine birds (Frisch, Green, & Figuerola, 2007). The occurrence of Dynamene species in a wide range of locations also confirms their dispersal capacity (Vieira et al, 2016).…”

“…However, some small invertebrates, such as free‐living isopods, are more prone to isolation due to life histories characterized by direct development and putatively reduced vagility, compared to other marine species with pelagic larvae (Thiel & Gutow, ). Long‐distance dispersal may occur through random events such as transport by shipping (Rumbold et al, ) or by rafting on detached macroalgae or floating debris (Thiel & Gutow, ). Effective recruitment following such mechanisms is, however, typically low due to high mortality and competition in the new habitat (Highsmith, ; Thiel & Gutow, ).…”

Review and guide to the isopods (Crustacea, Isopoda) of littoral and sublittoral marine habitats in the Southern California Bight

“…Body length to ~ 7.5 mm. See Holmes (1904 original description as Dynamene sculpta ), Richardson (1905a) , Menzies (1962a) , Miller (1968) , Schultz (1969) , Brusca (1980) , Shuster (1987 , 1992 ), Shuster and Wade (1991a , 1991b ), Rodríguez et al (1992) , SCAMIT (1994 – 2021 ), Shuster and Guthrie (1999) , Espinosa-Pérez and Hendrickx (2001a , 2001b , 2006 ), Hewitt and Campbell (2001) , Fairey et al (2002) , Smith et al (2003) , Ariyama and Otani (2004) , Ranasinghe et al (2003 , 2005 , 2007 , 2012 ), Brusca et al (2004 , 2007 ), Healey and Hovel (2004) , McLaughlin et al (2005) , Whitmore et al (2005) , Reed and Hovel (2006) , Sirota and Hovel (2006) , Montelli and Lewis (2008) , Cruz-García et al (2013) , Munguia and Shuster (2013) , Morales-Zarate et al (2016) , Gillett et al (2017 , 2022 ), Ramalhosa et al (2017) , Marchini et al (2018) , Rumbold et al (2018) , and Wetzer et al (2018) .…”

Inventory and Geographical Affinities of Algerian Cumacea, Isopoda, Mysida, Lophogastrida and Tanaidacea (Crustacea Peracarida)

“…For the Isopoda Paracerceis sculpta (Holmes, 1904), the type locality is San Clemente Island (California, USA) and its native range includes the Northeastern Pacific region including California and Mexico. Currently, this species is very widespread in the world [121], and recently recorded as NIS in the Argentinian waters [122]. P. sculpta is present over the whole Mediterranean Sea [10].…”