Rapp. Comm. int. Mer Médit., 36,2001
393
In the Malinska area (Krk Island, north Adriatic Sea) the invasive
green algaCaulerpa taxifoliawas firstly noted in November 1994. In
1996 the harbour settlement was eradicated (1) and this site remained
deprived of alga till now. But a few Caulerpa bushes at nearby loca-
tions which were not treated gave rise to an actual extension of alga in
the area of about 13 250 m2. Although tropical by its origin, Caulerpa
has survived low winter temperatures of only 9°C and by now it is
patchily distributed at the Malinska breakwater, the town beach and at
the Haludovo hotel complex. The settlement cartography was elabo-
rated by Zavodnik et al. (2).
The aim of present study was to get an insight into the mobile and
sediment living benthos covered by Caulerpacarpet. The area was
surveyed monthly from December 1997 till November 1999. Data
were compiled by divers’visual census and manual collections along
transects crossing the algal carpet, and by processing the sediment
taken from 25 x 25 cm plots.
At sites noted aboveCaulerpa was mostly anchored by cauloids in
the sandy sediment at a 6-8 m depth. Only a few fronds were attached
to a large litter and pebbles which supported other seaweeds too.
Sparse Zostera noltiiand Cymodocea nodosameadows also appeared
at some sites. In the upper sediment layer the seagrass roots and
Caulerpa cauloids were densely intermingled. A preliminary note on
associated seaweeds was provided previously (2). Red alga
e
L
a
u
rencia obtusa, Polysiphonia spp., Rhytiphloea tinctoriaa
n
d
Vidalia volubiliswere common in all seasons. Brown algae were rep-
resented by Dictyopteris polypoides, Dictyota dich o t
o
m
a, two
Halopteris species, and others. Among green algae, Cladophora albi-
da, C. proliferaand Ulva rigidawere outstanding. On Caulerpa
fronds 26 epiphytic species were noted.
Information on macrofauna noted by divers (i.e. visual census) and
on that extracted from sediment batches was rather diverse (Fig.1).
Total 114 invertebrate species were noted. Diversities of high taxa
were similar to those noted in the western Mediterranean (3, 4), except
of molluscs which at Malinska were more diverse. The presence index
of 40% or more was established only in the following species:
Musculus costulatus, Anomia sp., Lucinella divaricata, Parvicardium
ov
a
l
e, Plag
i
o
c a rdium papillosum, Gouldia minima, Pitar rudis,
Corbula gibba, Rissoa similis, Euspira nitida, Nassarius incrassatus,
Eunice oerstedi, Lumbrineris fragilis, Scoloplos armigerand Ophiura
albida. Dominate taxocoenes of the sediment living meiofauna were
Copepoda (62 %) and Nematoda (21 %) (A. Travizi, personal com-
munication). A detailed analysis on the matter will be presented in
another paper.
Figure 1. Species diversity of macrofauna in the Caulerpa taxi-
foliacommunity at Malinska.
Only 12 fish species were noted at our Caulerpa p
a t
c h e
s
.
Consequently, the ichthyofauna of studied sites was poor in compari-
son to fish populations of compact and well distributed Caulerpa com-
munities in the western Mediterranean (5, 6). Though, the stay of
Hippocampus ra
m
u
l
o
s
u
son Caulerpa fronds, and browsing on
Caulerpa of Sarpa salpashould be noted. Regrettably, biological data
on the sites of research before the Caulerpa invasion are lacking;
therefore, evaluation of eventual alterations of benthos is not possible.
Acknowledgement.
The research was supported by the Ministry for Science and
Technology of the Republic of Croatia (Project No. 00981302).
References
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BENTHOS OF THE CAULERPA TAXIFOLIASETTLEMENT AT MALINSKA (CROATIA, ADRIATIC SEA)
Ljiljana Ivesa*, Nevenka Zavodnik and Andrej Jaklin
Center for Marine Research, Rudjer Boskovic Institute, Rovinj, Croatia - ivesa@cim.irb.hr
Abstract
Diversity of macrobenthos in the Caulerpa taxifolia settlement at Malinska was analyzed. In general, ?ora and fauna are alike to those in
the western Mediterranean.
Key words: zoobenthos, phytobenthos, Adriatic Sea, Caulerpa taxifolia
