Biology Reference
In-Depth Information
sediment via roots and leaf uptake is considered of secondary importance (Pedersen
and Borum 1993; Ceccherelli and Cinelli 1997),
Caulerpa
utilizes both sediment
and water column nutrients (Williams 1984; Chisholm and Jaubert 1997).
Caulerpa
also can modify organic and inorganic components of the sediment (Chisholm and
Moulin 2003). Thus,
Caulerpa
may receive a selective advantage in nutrient-limited
environments when competing with seagrasses (Williams 1984; Ceccherelli and
Cinelli 1997, 1999b; Ceccherelli and Sechi 2002).
15.4 Popularityof
Caulerpa
in the Aquarium Industry
While many of the economic and ecological impacts of the aquarium hobbyist
industry can be enumerated (e.g., Padilla and Williams 2004; Walters et al. 2006;
Zaleski and Murray 2006), one critical aspect that cannot be quantified is the
number of accidental and purposeful releases of organisms from aquaria into
coastal waterways. In spite of missing information, some of the most harmful inva-
sive species that have become established in global waters are presumed to be the
result of aquarium releases (e.g., Whitfield et al. 2002; Semmens et al. 2004; Ruiz-
Carus et al. 2006). The source of the US and Australian invasions of
C. taxifolia
will never be known, but the similarity to the Mediterranean invasion lends support
to aquarium releases (Stam et al. 2006). Currently in the USA there are over 11 million
aquarium hobbyists spending billions of dollars annually to have colorful marine
communities in their homes or businesses (Kay and Hoyle 2001).
In spite of the invasive reputation, many members of the genus
Caulerpa
remain
extremely popular with aquarium hobbyists (Walters et al. 2006; Zaleski and
Murray 2006).
Caulerpa
sp. are quintessential-looking marine aquarium plants,
difficult to kill, propagate easily, remove nutrients, and some are also fish food. In
three 2006 publications, the popularity and ease with which
Caulerpa
is dispersed
within US boundaries via the aquarium industry was documented. Zaleski and
Murray (2006) focused on availability of the genus
Caulerpa
in retail shops in
southern California immediately after the first Californian invasion was reported.
Zaleski and Murray (2006) found no seaweeds for sale in large corporate/franchise
pet stores, so focused on independent, nonfranchise stores that specialized in orna-
mental organisms for hobbyists. In total, ten species of
Caulerpa
were for sale by
at least one shop for 52% of 50 stores visited between November 2000 and August
2001. Fourteen percent of the shops visited had
C. taxifolia
(Zaleski and Murray
2006). None was the invasive strain (Stam et al. 2006). In 2006-2007, S. Diaz and
S. Murray (unpublished data) resurveyed the same southern California shops.
Forty-four were still in business. In spite of the California code banning nine spe-
cies of
Caulerpa
, including
C. taxifolia
, and all the publicity associated with the
two Californian invasions, 52% of the 44 remaining shops still sold at least one
species of
Caulerpa
and four had
C. taxifolia
(not identified to strain, S. Diaz and
S. Murray unpublished data). Two other banned species,
C. racemosa
and feathery
C. sertularioides
, also were for sale (S. Diaz and S. Murray unpublished data).
