ecological effects of marine protected areas empafish project ...

EMPAFISH Booklet no. 1 Ecological effects of Atlanto-Mediterranean MPAs in the EU
assemblage seemed to be affected, exhibiting low values of specific richness
and total abundance in sites where these encrusting coralline algae dominated
(Cianciolo et al. 2005), particularly within the integral reserve.
The population structure of two species of sea urchins (Paracentrotus lividus
and Arbacia lixula) has been monitoring within the MPA perimeter (integral
zone vs. general and partial reserve) unfortunately only since 2004. The
project is still in progress and data are only preliminary available.
� Effects on habitat (impact of recreational activities)
When looking at impact of recreational activities within MPAs, little scientific
knowledge seems to support MPA management decision-making process.
Some studies carried out in the Ustica Island MPA attempted to evaluate the
effects of human recreational activities on different marine communities,
indicating potential management solutions to limit their damage. Ustica Island
receives ca. 35,000 tourists per summer (Badalamenti et al. 2000).
Research was carried out in the field, by quantifying the real impact of
tourists and by simulation experiments, on four main recreational activities:
scuba-diving in the infralittoral habitats, the boat anchoring on the Posidonia
oceanica meadows, the human trampling on the shallow algal communities
and the feeding by MPA visitors on the coastal fishes.
At Ustica, an estimation of 10,000 divers per year is plausible. Direct
observations were used to describe interactions between divers, substrate and
marine organisms in eight common habitats of the Mediterranean subtidal
(Milazzo et al. submitted). Data on habitats’ availability, divers’ permanence
in each habitat and immediate damages (or conditioning) on marine species
were collected. Analyses showed that standardized preference of habitat of
divers was highest for horizontal photophilic community, marine caves and
sciaphilic walls. Contacts were voluntary on the 30% of occasions. Immediate
damages were mainly recorded on the slow-growing benthic species
Leptosammia pruvoti, Astroides calycularis and Myriapora truncata belonging
to marine caves and sciaphilic walls. Contacts in other habitats, although
numerous, did not produce any evident damage on the immediate.
Behavioural responses (i.e. unnatural aggregations) of several fish species
occurred frequently (58%) when divers had contacts with the substrate.
Simulation experiments on the boat anchoring activity revealed that the
damage was strongly dependent on the anchor typology adopted and that
weighing was the critical stage during the anchoring process. Generally the
use of the Hall type anchor seemed to be preferable to minimise the impact
on the Posidonia meadow in comparison with the Danforth and Folding
grapnel anchor types.
Erect macroalgae are very sensitive to human trampling and even relatively
low intensities of this human disturbance may be non-sustainable for this
shallow assemblage (Milazzo et al. 2002). However, after disturbance ceased,
the macroalgal recovery seemed to be very rapid: the higher the impact on
the system the more rapid the recovery rate (Milazzo et al., 2004). In the
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