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International Journal of Marine Science 2014, Vol.4, No.14: 134-142
http://ijms.sophiapublisher.com
138
more antropic influence and hence a highest level of
eutrophization (Díaz-Asencio et al., 2005; Seisdedo,
2006), which could facilitate the development not only
of Asian green mussels but also of the associated fauna.
Both, total biomass and biomass of epifauna associated
to each mussel were greater at those sites (PG and M7)
near to Cienfuegos City. Based on the information
given by specialists of the local environmental office,
the city of Cienfuegos contributes the most to the bay
contamination with around 1936 tons of BOD
(biochemical oxygen demand) per year (C
Baute-Álvarez pers. comm. March 4, 2013).
Generally, the sites in which Asian green mussels have
been reported as an invasive species are considered
trophically enriched. The source of such enrichment
could be mainly antropic, like in Bays (Buddo et al.,
2003) or natural due to any upwelling process
(Villafranca and Jiménez, 2006). Such sites could then
be identified, for the Caribbean and Central Atlantic
region as ¨high risk sites¨ to be invaded by
P. viridis
or
other species with similar characteristics; mostly if
these sites were exposed to high boats traffic. Other
bays in Cuba could be some of these ¨high risk sites¨.
The high growth rate of Asian green mussel is related
to a high filtration rate of organic material, and so its
development is favored in those environments
trophically enriched (Hawkins et al., 1998).
Polychaetes semi-sessile forms eventually may not
appear within the sampling units or even escape when
removing mussels. That is why further analysis is
recommended in future studies especially designed to
find out all this non-sessile forms. Liñero-Arana (1999)
reports at least 11 species of polychaetes associated to
P.
viridis
in Araya peninsula, Venezuela. In this study,
only six species belonging to families Nereididae,
Syllidae, Sabellidae, Terebellidae y Cirratulidae, were
present. Some of this species have been associated to
soft sediments with organic material accumulations
(Díaz-Díaz et al., 2009).
Specimens of
P. viridis
and
I. alatus
were seen
cohabiting in many sampling times. Although this
study does not provide enough evidences to discard at
all the possibility that both species could compete for
substrate, the hypothesis of mutualism seems to be
more plausible at least for the current mussel densities.
It was well established that other mollusks (bivalves or
gastropods), as well as barnacles, sponges, sea squirts
and bryozoans, grow and develop together with
mussels without noticeable stressful effects. The
species richness values recorded in the PG and M7,
added to what was found in PC regarding the
characteristics of the members of the epifauna
associated to
P. viridis
, suggest a little or no exclusive
ecological interactions.
After more than eight years of the first report, the
mussels in Cienfuegos bay cohabit with other 39
epifauna species, many of which were also observed in
areas devoid of mussels inside the bay. More than 50 %
of the mollusks species that were found have existed
for several years in the coastal area of the bay,
particularly in the same biotopes where
P. viridis
are
currently reported (Díaz-Asencio et al., 2005). Most of
the species that make up the remaining percentage (not
found in the present study but reported by those authors)
are species characteristic of certain biotopes not
sampled because they are not invaded.
Irregularities created by shells when mussels are
developing, serve up as shelter for other species that sit
or crawl on them, thereby increasing the diversity of
associated biological community. A similar result was
obtained by Villafranca and Jiménez (2004, 2006),
studying the mollusk communities associated to
P.
viridis
in Araya peninsula, Venezuela. Those authors
also argument that the retained water between mussels,
and feces and pseudofeces depositions around them,
stimulate trophic enrichment and increase abundance
and diversity of associated species. From this point of
view, P. viridis might acts as an engineer species as well
as can be seen with the mussel
Limnoperna fortunei
(golden mussel) in southern South America (Darrigran
and Damborenea, 2011). One of the three barnacle
species (Amphibalanus reticulatus) has been reported
for first time for Cuban waters (Lopeztegui and Varela,
2012); it was found fixed on mussels shells.
The information providing by this study seems to be
against the hypothesis that
P. viridis
represents an
ecological damage to the ecosystem, but it is not
enough to reject that hypothesis. Maybe the mussel
density at the sampled year, around 156 ind/m
2
(Lopeztegui - Castillo et al., 2014), was not great
enough to cause a significant negative impact on
ecosystem. A negative environmental impact including