ecological effects of marine protected areas empafish project ...

EMPAFISH Booklet no. 1 Ecological effects of Atlanto-Mediterranean MPAs in the EU
et al. 1995). The fish assemblage at each area was censused using the strip
transect, the stationary visual census and the spatial census techniques. The
estimated abundance and size of fish species were recorded on suitable
boards. Fish abundance, community structure indices (d', H' and J') and a
multivariate analysis of data were computed. Fish biomass was also estimated
from the length-frequency distributions of fishes using length-weight
relationships. Sparids characterized the fish assemblage in ARA while labrids
were the most representative species in WRB and ERB. ARA displayed values
of diversity indices, abundance and biomass significantly higher than those
registered in SB and close to those obtained in POA and especially WRB and
ERB. From our results it stems that the fish biomass and abundance in ARA
are lower than those estimated in other artificial reefs in the Mediterranean
Sea. These studies were an attempt to understand the role played by artificial
reefs in influencing the composition of nekton assemblages in oligotrophic
waters, such as those in the Southern Tyrrhenian Sea.
A review of the efficiency and role of the Castellammare artificial reefs is
reported by Badalamenti et al. (2000a) and D’Anna et al. (2000).
� Traditional and experimental FADs
An experimental bottom FAD, stretching 50 m 2 and composed of 36 buoyant
polypropylene ropes frayed on the top, was deployed on a sandy area at a
depth of 14m in the Gulf of Castellammare (NW Sicily) (D’Anna et al. 1997).
The FAD was constructed at the aim to attract fish and to diversify the soft
bottom fish assemblage. In order to study the fish colonisation of the FAD we
carried out 38 visual census counts over the July 1994 to September 1995
period. Fish belonging to 22 taxa, including mainly sparids and labrids, were
recorded during the survey. The most frequent and abundant species were
Spicara maena, Serranus scriba Chromis chromis, Symphodus tinca, S.
cinereus, Boops boops, and Seriola dumerili. Patterns of colonisation
distinguished three main phases: Phase A (15 - 95 days after the FAD
deployment) was characterised by a fluctuation of the species richness values,
high dominance and low diversity. The main pioneer species were: Spicara
maena, Balistes carolinensis, Seriola dumerili and Lithognathus mormyrus.
Phase B (96 - 294 days) showed a decrease of abundance and increase of
diversity and evenness values. Phase C (295 - 414 days) diplayed an increase
of number of species and abundance, mainly due to the recruitment of some
juveniles of pelagic and nekto-benthic species. Statistical analysis detected
quantitative differences between the fish assemblages of the upper and lower
side of the FAD. Cluster analysis, performed on quantitative matrix of
abundance excluding species with a frequency of occurrence