From introduced species to invader: what determines variation in the success ofCodium fragile ssp.tomentosoides (Chlorophyta) in the North Atlantic Ocean?

Abstract

The green alga Codium fragile ssp. tomentosoides (Chlorophyta) has been introduced accidentally and successfully from Japan to many shores of the northern and southern hemispheres, including those of the Northeast and Northwest Atlantic Ocean. On most European coasts, Codium occurs regularly but at low abundances in the intertidal zone and is absent from subtidal habitats, tn contrast. Codium is extremely abundant in subtidal kelp beds in the Northwest Atlantic Ocean where it often reaches nuisance proportions. This differential success cannot be accounted for by either the properties of the invader or by physico-chemical differences between invaded coasts. A theoretical comparison between two regions on opposite sides of the Atlantic Ocean, i.e. Eastern Nova Scotia, Canada, and south central Britain, illustrates how the resident benthic community may determine the difference in relative abundance of Codium in subtidal habitats between northeast America and Europe. In this review, low floral species diversity, biological disturbance and facilitation by a previous species invasion are suggested as potential factors for the establishment, success and abundance of Codium in the Northwest Atlantic Ocean, but these require testing in field experiments. I N T R O D U C T I O N S t u d i e s of t h e e c o l o g y of s p e c i e s i n t r o d u c t i o n s into n o ve l m a r i n e e n v i r o n m e n t s h a v e o f t e n e m p h a s i z e d (1) t h e p r o p e r t i e s of s u c c e s s f u l l y i n v a d i n g species, (2) t h e c h a r a c t e ristics of f r e q u e n t l y i n v a d e d c o m m u n i t i e s or (3) t h e t r a n s p o r t v e c t o r s i n v o l v e d in overc o m i n g b a r r i e r s of space, c l i m a t e or h a b i t a t (e.g. C a r l t o n

Seaweed invasions: conclusions and future directions

“…If there are any broad traits common to most (but not all) invasive seaweeds, it is the capacity for rapid growth and means of effecting both short and long-distance dispersal (Valentine et al 2007), but many seaweeds manifest these properties without showing any sign of being invasive. Moreover, even the same species can be invasive in one area but not in another (e.g., Trowbridge 1998, Chapman 1999 or, in the same area, at one time but not another we.g., Undaria pinnatifida (Harvey) Suringar, CR Johnson, pers. obs.x.…”

How an introduced seaweed can affect epibiota diversity in different coastal systems

“…Bertness 1984;Vitousek et al 1996;Grosholz et al 2000;Sakai et al 2001;Steneck and Carlton 2001;Ross et al 2004). These impacts may vary greatly depending on the invaded communities (Berman et al 1992;Chapman 1999). For example, the Japanese seaweed Codium fragile (Sur.)…”

“…tomentosoides (van Goor) Silva (hereafter Codium) was introduced to the European and North American coasts of the Atlantic Ocean at the beginning and in the latter half of the 20th century, respectively. While Codium occurs in low abundances intertidally on many European shores, it can have detrimental effects on subtidal kelp communities in the northeast Atlantic Ocean, where the seaweed often reaches nuisance proportions (Chapman 1999;Chapman et al 2002).…”

“…They are often unpredictable and cannot be generalised, and must be assessed separately for each invaded assemblage. To our knowledge, only few studies compare the impacts of the same invasive species in different systems (Berman et al 1992;Grosholz and Ruiz 1996;Chapman 1999).…”

Antithamnion nipponicum(Ceramiaceae, Rhodophyta), incorrectly known asA. pectinatumin western Europe, is a recent introduction along the North Carolina and Pacific coasts of North America

“…tomentosoides (van Goor) P.C. Silva along the Mid-Atlantic USA coast (Chapman, 1998), and of Undaria Suringar in western Europe (Curiel et al, 1998). We need to make a molecular comparison of type locality material of A. hubbsii before subsuming this species within A. nipponicum.…”