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Hypotheses on the spatial and temporal distribution of sessile assemblages in sub- merged marine caves have rarely been tested. Classically, the distribution of cave benthos has been related mainly to the physical gradients along the exterior-interior axis. Using a multifactorial sam- pling design, we examined the distribution of species assemblages within 3 different caves in South- ern Italy. Non-destructive sampling was repeated at 4 different times over a period of 11 mo. Results showed an overall pattern of change in the structure of the assemblages along the exterior-interior axis of the 3 caves (i.e. among sectors). Significant differences in species assemblages, however, were also observed within sectors (i.e. among areas), and changes in assemblages varied inconsistently with time and among caves. This result suggests a high complexity of the processes determining spatio-temporal distribution patterns in marine caves, which are context- and scale-dependent. Results also showed the uniqueness of these assemblages, which has important implications for their conservation and management.

Fish assemblages of three shallow marine caves from the Salento Peninsula (Apulia, SE Italy) were investigated in July 2000. Data were collected in situ by using visual census. A total of nineteen fish species were recorded inside the caves. The species richness generally displayed a similar pattern in all three caves, decreasing from the entrance towards the innermost sections, whereas the patterns of total fish abundance differed among caves. Apogon imberbis (mainly represented by juveniles) was the most important species in terms of number of individuals (accounting for more than 85% of the censused fish) and showed a fairly even distribution inside the investigated caves. Without the numerical contribution of A. imberbis, fish abundance decreased from the entrance to the inner sections and this pattern was common to all three caves. Juvenile fishes of economic interest (e. g., Diplodus vulgaris and Epinephelus marginatus) were also recorded inside. The present study suggests that: (1) environmental constraints could affect distribution patterns in fish species richness and in the abundance of several fish along the axis of “blind caves” (with a single entrance), as already observed for sessile benthos and plankton assemblages; (2) shallow marine caves of the Salento Peninsula could exert the role of refuge and/or nursery for some littoral fish species during the adult and/or juvenile stages of their life histories.

Fish assemblages were assessed by visual census in sublittoral rocky reefs at the Tavolara-Punta Coda Cavallo Marine Protected Area (TMPA; Mediterranean Sea) and compared among locations characterised by different protection levels: no-take/no-access zones, two types of partial protected areas (PPAs, where professional and recreational fishing are regulated in a different way) and locations outside the TMPA. Fish assemblage structures evaluated on abundance data did not differ among different protection levels, while no-take/no-access zones clearly differed from the rest when data were expressed as biomass. Biomass of many target species was higher in no-take/no-access zones mostly due to greater fish size rather than density. For some fish (e.g. the dusky grouper Epinephelus marginatus), however, both greater density and larger size contributed to the greater biomass in no-take/no-access zones. No differences were found between the two types of PPAs, and between PPAs and the locations outside the TMPA, in terms of assemblage structures, and in density, size and biomass of target species. These results suggest the need to 1) improve management in PPAs or re-think of their role, and 2) quantitatively assess pressure of both professional and recreational fishing operating within and adjacent to MPAs, in order to allow MPAs to set up proper regulations (e.g. limiting professional or recreational fishermen, number and type of gears), and 2) achieve the best balance between ecological targets and reduction of conflicts among different categories of marine resource users.

Fish assemblages associated with marine caves and rocky cliffs were investigated in the Salento Peninsula (SE Italy, Mediterranean Sea) by using visual census methods. Sampling was done at three sites, each of which included 4 habitat types: the external and the internal portions of caves, and shallow and deep rocky cliffs. 10 and 13 species were found exclusively inside cave habitats (e.g. Corcyrogobius lichtensteini, Thorogobius ephippiatus and Grammonus ater) or in rocky cliffs (e.g. Diplodus annularis, Sarpa salpa, Sparisoma cretense, Spondyliosoma cantharus), respectively. The four habitat types shared 10 species, and the external portions of the caves shared the most species (both with the internal cave portions and the external rocky cliffs). As a general rule, dissimilarity in the fish assemblage structure between habitats was far greater than dissimilarity between sites. Apogon imberbis (mostly associated with caves) and Chromis chromis (typifying rocky cliffs, mainly the deep ones) mostly contributed to dissimilarities between caves and rocky cliffs. Apogon imberbis (mostly associated with internal caves) and Coris julis (mainly associated to external cave portions) contributed strongly to dissimilarities between internal and external cave portions, while C. chromis, Symphodus mediterraneus and C. julis (associated with the deeper cliffs) and Thalassoma pavo (mostly present in shallow cliffs) differentiated deep and shallow cliffs. Diplodus vulgaris, Oblada melanura and Mullus surmuletus showed a marked increase in density during the cold season in the caves. These results show that fish assemblages associated with rocky reefs rich in marine caves (in terms of relative densities, species composition, species richness, exclusive species and presence of juveniles of some valuable species) may be affected by the peculiar ecological conditions within caves, which could provide additional resources for fishes (e.g. food availability, refuge against predators, sand patches within a rocky matrix) compared to rocky reefs without caves. These results suggest that stretches of rocky coasts rich in marine caves should be considered within management/conservation programs (e.g. when establishing Marine Protected Areas).

Conservation of the Mediterranean marine ecosystems is particularly challenging; high biodiversity is combined with high human population densities and a long history of resource exploitation. Residents and users of coastal areas often perceive marine conservation and manage- ment as limiting factors to economic development. Under these conditions, the creation of compre- hensive systems of marine protected areas (MPAs) can be problematic. We selected a stretch of coast in southern Italy as a representative example of a Mediterranean coastline and nearshore marine ecosystems, featuring a complex matrix of vulnerable habitats in a landscape fragmented by multiple human activities and associated stressors. Through the use of site-selection algorithms, we investi- gated how human activities constrain MPA planning. Rather than assuming that patches of the same habitat found at different locations are interchangeable, we considered the scenario of a heteroge- neous landscape of human impacts creating high variability in habitat quality. Despite widespread human influence, identification of portions of habitats to be protected from direct human disturbance as core no-take areas is still possible using the inclusion of 10 and 30% of low and high priority habi- tat, respectively, in reserves as a conservation target. Implementation of MPAs with a limited protec- tion scheme that also include several small no-take areas could represent a feasible strategy for the conservation of Mediterranean coastal marine habitats. Moreover, MPAs could be combined with coastal zoning of activities as a means of further controlling effects over broader areas and allowing for recovery of degraded areas. Site-selection algorithms are invaluable tools for conservation plan- ning. However, careful consideration of the potential constraints imposed by local human activities and future research aimed at filling existing gaps in understanding the ecology are crucial for mak- ing this approach useful in marine conservation planning.

Marine protected areas (MPAs) have become popular tools worldwide for ecosystem conservation and fishery management. Fish assemblages can benefit from protection provided by MPAs, especially those that include fully no-take reserves. Fish response to protection can thus be used to evaluate the effectiveness of marine reserves. Most target fish are high-level predators and their overfishing may affect entire communities through trophic cascades. In the Mediterranean rocky sublittoral, marine reserves may allow fish predators of sea urchins to recover and thus whole communities to be restored from coralline barrens to macroalgae. Such direct and indirect reserve effects, however, are likely to be related to the enforcement implemented. In Italy, many MPAs that include no-take reserves have been declared, but little effort has been spent to enforce them. This is a worldwide phenomenon (although more common in some regions than others) that may cause MPAs and reserves to fail to meet their targets. We found that 3 of 15 Italian marine reserves investigated had adequate enforcement, and that patterns of recovery of target fish were related to enforcement. No responses were detected when all reserves were analyzed as a whole, suggesting enforcement as an important factor to be considered in future studies particularly to avoid that positive ecological responses in properly managed reserves can be masked by neutral/negative results in paper parks. Positive responses were observed for large piscivores (e.g. dusky groupers) and sea urchin predators at reserves where enforcement was effective. Those reserves with low or null enforcement did not differ from fished areas.

In both protected and fished rocky reefs in the southern Adriatic Sea, the behaviour of the sea breams Diplodus sargus and D. vulgaris (both targeted by spear-fishing) in the presence of divers was found to be mostly negative (i.e. escape response). However, at protected reefs sea breams frequently swam into the closest shelters, whereas in fished reefs they mostly escaped in open water. This study suggests that spear-fishing may alter the escape response of fish from natural predators and that marine reserves may re-establish natural behaviour patterns.