Image Credit: Fran Lapolla

1
Megabalanus coccopoma and Mytella charruana
Authors Alan Power, Thomas Bliss, Marcy Mitchell
Randal Walker Address University of Georgia
Marine Extension Service, Shellfish Research
Laboratory, 20 Ocean Science Circle, Savannah, GA
31411 Email alanpowr_at_uga.edu Website
www.marex.uga.edu/shellfish Telephone 912 598
2348
Theyre here!
scutum Image Credits Marcy Mitchell
a.
Megabalanus coccopoma (Darwin, 1854) Native
distribution Pacific Coast of Central
America. Introduced distribution Brazil, North
Sea, Louisiana, Georgia. Introduction vectors
Ballast water ship fouling. Potential impacts
Competition with natives, and fouling costs.
Habitat Inhabits low-intertidal zone. In
Georgia, it has been observed attached to
pilings, buoys, and vessel hulls. Notes
Barnacle has a conspicuous pink color and can
reach lt50 mm in height and diameter. First
documented in Georgia in June 2006. The species
resembles the cosmopolitan Megabalanus
tintinnabulum (Linnaeus, 1758).
References Advisory Committee on the Marine
Environment. Report of the Working Group on
Introductions and Transfers of Marine Organisms.
Vancouver, Canada, 26-28 March 2003.
ICESCM2003/ACME04 Ref. E, F. Breves-Ramos, A.,
H.P. Lavrado, A.O.R. Junqueira, S.H.G. Silva.
2005. Succession in Rocky Intertidal Benthic
Communities in Areas with Different Pollution
Levels at Guanabara Bay (RJ-Brazil). Brazilian
Archives of Biology and Technology 48(6)
951-965. Kerckhof, F. 2006. Exotic invasive
species in the marine ecosystem the situation in
Belgian marine waters. Royal Belgian Institute
of Natural Sciences, Management Unit of the North
Sea Mathematical Models, Marine Environmental
Management Section. SOS Invasions. Perreault,
Ray T, 2004.  An exotic tropical barnacle,
Megabalanus coccopoma (Darwin, 1854), in
Louisiana its probable arrival and environmental
implications.  Proceedings of the Louisiana
Academy of Sciences 66, 16 November 2003(2004)
13-16. Mytella charruana (d'Orbigny, 1846)
Native distribution Venezuala to Argentina
eastern Pacific Ocean. Introduced distribution
Florida, Georgia. Introduction vectors Ballast
water ship fouling. Potential impacts
Competition with natives and fouling costs.
Habitat In its native range it occurs in
shallow lagoons and mud-flats in bays. In
Georgia it has been observed attached to floating
docks and to vessel hulls. The salinity
tolerance range is 14 - 41 ppt.Notes Brown,
light green, yellow, or black in color and can be
uniform or banded. The species resembles the
edible blue mussel Mytilus edulis (Linnaeus,
1758) which occasionally occurs in Georgia. It
first appeared in Florida in 1986 and was first
documented in Georgia in August 2006.
References Boudreaux, M. L. and L. J. Walters,
2006. Mytella charruana (Bivalvia Mytilidae) a
new, invasive bivalve in Mosquito Lagoon,
Florida. The Nautilus 120(1) 34-36. Keen, A.
M. 1971. Sea shells of tropical west America.
Marine mollusks from Baja California to Peru.
Palo Alto, CA Stanford University Press. 1065
pp. Sibaja, W. G. 1985. Shell parameters of
Mytella strigata in Pacific Costa-Rica. Revista
de Biologia Tropical 3359-60. Soot-Ryen, T.
1955. A report on the family Mytilidae. Allan
Hancock Pacific Expeditions 201-175. Miguel
E.G.C. de Oliveira, Claudia A.M. Russo, Cristiano
Lazoski, Paulo Roberto F.G. Vianna and Antonio M.
Solé-Cava, 2005. Genetic variation and population
structure of two species of neo-tropical
mud-mussels (Mytella spp). Genet. Mol. Res. 4
(2) 197-202.
a. U.S. Mytella charruana distribution
b.

• M. coccopoma tergum
• M. coccopoma scutum
• Image Credits Marcy Mitchell

a.
b. Southeastern U.S. M. charruana distribution
During summer 2006, two new nonindigenous aquatic
marine species were observed in coastal Georgia,
the Charrua mussel, Mytella charruana, and the
acorn barnacle, Megabalanus coccopoma. The
vector for these introductions is unknown however
the majority of other introduced marine species
of molluscs and crustaceans in the region arrived
on ships hulls and in ballast water. Despite
recent advances in ballast water management
regulations, shipping remains a primary pathway
for marine introductions. Given growth trends in
the ports of Savannah and Charleston with markets
worldwide, the rate of new species introductions
has the potential to rise. More introductions
have already been observed in the present decade
than in those previous. Early detection and
rapid response management plans should be
developed on a regional scale to meet this
challenge. It is too soon to tell if there will
be any significant fouling impacts associated
with these latest species. Mytella charruana was
first reported in Jacksonville, Florida in 1986
however, a cold winter prevented the population
from establishing. A separate introduction
occurred in 2004 in the Indian River Lagoon
System however this population has remained small
(lt100 specimens collected). Interestingly the
population documented in Georgia in 2006 appears
to have very different characteristics with
individuals attaining much larger sizes (56 mm
versus 27 mm shell length) and occurring in high
densities (gt6,000 m2). Research is currently
underway to document the reproductive biology and
the seasonal population dynamics. Please
contribute to developing our knowledge base by
reporting any observed occurrences taking note of
as much of the following information as possible
location GPS, number of specimens (living or
dead), their sizes, what attached to, and water
depth, temperature and salinity.
b.
M. coccopoma growing on vessel hull Image Credit
Alan Power
c. U.S. Megabalanus coccopoma distribution
M. coccopoma growing on Sea Buoy Image Credit
Fran Lapolla
d. Southeastern U.S. M. coccopoma distribution
Image Credit Fran Lapolla
A Unit of the Public Service Outreach Division
of the University of Georgia
Mytella charruana Image Credits Marcy Mitchel
Alan Powerl
Megabalanus coccopoma Image Credits Fran Lapolla