Proceedings of the 12th European Geoparks Conference
National Park of Cilento, Vallo di Diano and Alburni Geopark – Italy 4-6 September 2013
The map of the marine landscapes and habitats of Cilento, Vallo di Diano and Alburni Geopark. Linking geo- and bio- diversity with a multiscalar approach Silvana D’Angelo (a), Floriana Di Stefano (b), Andrea Fiorentino (a), Maria Teresa Lettieri (a), Giovanni Fulvio Russo (b) & Crescenzo Violante (c) _____________________________________________________________________________________________________________________________________________________ (a) Geological Survey of Italy/Land Protection and Georesources Department – ISPRA, Via Brancati, 48, 00144 Roma, Italy –
[email protected] (b) Department of Environmental Science (DISAM), “Parthenope” University of Naples, Centro Direzionale, Isola C4, 80143 Napoli, Italy (c) Insitute for Coastal and Marine Environment (IAMC), National Research Council (CNR). Calata Porta di Massa, 80133 Napoli, Italy
INTRODUCTION The Geological Map of the Cilento, Vallo di Diano and Alburni Geopark includes, for the first time in Italy, marine areas. The work was carried out by the Geological Survey of Italy (ISPRA), in collaboration with the Italian National Research Council (CNR) and the University “Parthenope” of Naples (DISAM). The map was realized at 1:110,000 scale for the entire Geopark, covering a marine area of 460 square kilometers, until a depth of -100 m. A detailed map of the Marine Protected Area “Santa Maria di Castellabate” was produced at 1:30,000 scale. The seafloor was described according to a classification based on geomorphology, geological composition and dominant organisms. The cartographic representation is largely based on the morphological features derived by a detailed bathymetry, completed by geological seabed data resulting from the Italian Geological Mapping Project at 1:50,000 scale (CARG Project). Biological data have been complemented by ROV inspections. MAP DESCRIPTION The attention has been focused on the relationship between the seafloor geology and morphology and the flora and fauna assemblages that live therein. All of these components contribute to characterize the diversity and complexity of the submerged landscape. Information has been adjusted to the scale of representation. The main map scale (1:110,000) allows for a general overview of the submerged landscape of the Cilento coast. Many geological structures described in the emerged areas of the Park continue under the sea surface, particularly in the mountain areas of Mount Stella, Mount Bulgheria and the Gelbison-Castelluccio ridge, whereas in the coastal plains facing the rivers (Alento, Lambro, Mingardo and Bussento) sediments coming from land are reworked by the wave action and redistributed according to the dynamics of the coastal currents, originating extended submerged plains. Rock buttresses lean forward offshore and are massively covered by calcareous bioconstructions, interrupted and locally half buried
by sands and gravels deriving from their dismantling. Benthic assemblages, highly diversified depending on the type of substrate (rock, bioconstructions or different kinds of sediments), are associated to each morphology (Tab.1). The Punta Licosa area, which is part of one of the two Marine Protected Areas included in the Park, has been mapped at a more detailed scale (1:30,000) as well, in order to evidence its great habitat richness. MAP OF SUBMERGED LANDSCAPES AT 1:110,000 SCALE Approximately 30% of the submerged areas of the Cilento coast is constituted by hard bottoms. Banks have been mapped distinguishing them according to the grain size of their sediment covers. Hard substrates are seldom represented by rocks directly exposed in the water, since they are covered everywhere by calcareous bioconstructions (coralligenous). Such constructions form also on sandy seafloors where algae with calcareous thalli produce lumps of cemented grains (melobesias). On top of them organisms with calcareous skeletons, such as madrepores, serpulids, bryozoans, molluscs, etc., settle. Seagrasses, like Posidonia oceanica and Cymodocea nodosa, form extended meadows colonizing sandy bottoms down to more than -30 m depth. Deeper than the lower boundary of these extended meadows, sediments are organogenic sands and gravels, characterized by calcareous shell fragments of the numerous and abundant species of foraminifers, molluscs, bryozoans and serpulids, which inhabit the Posidonia meadows. Wherever the sediments covering the rocky substrate are muddier, soft corals (Pennatulacea and Alcyonacea) prevail. Terraces downstepping offshore are covered by sediments of mixed grain size, colonized by Posidonia meadows or incrusted by coralligenous organisms. Submerged plains form in the center of bays bordered by promontories and at river mouths. In these areas sediments are generally fine (sands, muddy sands and silts) and the organisms are mainly fossorious, which actively dig sediments aiming at sheltering (burrows) and feeding (organic debris).
D’ANGELO ET AL.
2 Morphology Rocky bank
Geological composition Rocky substrate covered by coralligenous bioconstructions Rocky substrate covered by sediments varying from organogenic sands to gravels, locally muds Rocky substrate covered by biogenic gravels and coarse sands. Rocky substrate covered by biodetrital sands.
Dominant organisms Calcareous algae, animals with calcareous skeleton (sponges, corals, serpulids, bryozoans, molluscs) Buttresses of shelf coralligenous and dense populations of echiurid species. Phanerogam meadows (Posidonia oceanica and Cymodocea nodosa). Posidonia oceanica patches or meadows Soft corals (Alcyonacea)
Relict beach ridge
Rocky substrate mainly covered by terrigenous muds anf intermittently by biodetrital sands. Sands formed in subaerial environment
Fan delta
Fluvial mixed sediments
Shallow sandy plain
Sands characterized by ripple marks; muddy component increases seaward.
Shelf muddy plain
Muds with varying percentages of sands.
Ledge
Rocky layers covered by bioturbated mud.
Deep terrace with muddy bioclastic cover Rock
Terrigenous muds mixed with bioclasts.
Fossorious organisms, mainly sospensivorous mollusks and peracarid crustaceans. Fossorious organisms, mainly depositivorous molluscs and polychaetes. Fossorious organisms resistant to wave perturbation. Cockles worms and crustaceans in the muddy part. Phanerogam meadows in patches. Fossorious organisms, including echinoderms, worms, molluscs and crustaceans. Locally “fields” of soft pivoting corals (Pennatulacea). Polychaetes and crustaceans burrows and very muddied shelf coralligenous Fossorious organisms, such as polychaetes and crustaceans.
Rocky outcrop constituted by arenaceous rocks.
Hydroids and stoloniferous Alcyonacea
Bank with mixed organogenic sediments Bank with coarse organogenic cover Bank with sandy organogenic cover Bank with muddy cover
Tab. 1 – Synthetic description of the features represented on the map at 1:110,000 scale
Sands accumulate in the submerged area exposed to wave action. They are locally characterized by current ripple marks and are colonized by fossorious organisms able to resist to wave perturbation, like cockles (Donax spp. and Chamelea gallina). The muddy fractions increase offshore and the submerged plains host fossorious “pipebuilders” organisms, such as worms and crustaceans. The plains can be locally covered by Posidonia oceanica meadows or, in case of finer sediments, by Cymodocea nodosa. Sands can be locally found at greater depths, beyond the muddy plains. In these cases they are the remnants of ancient relict beaches, which had formed during previous sea level low stands. MAP OF THE MARINE PROTECTED AREA “SANTA MARIA DI CASTELLABATE” AT 1:30,000 SCALE This area has been chosen to elaborate an experimental map in order to verify how much detail can be obtained in the description of marine landscapes by increasing the scale of representation. For example, the area, which in the 1:110,000 scale map is represented as a single bank in continuity with the Punta Licosa promontory, covered by mixed sediments, in the 1:30,000 scale map becomes a very diverse zone, with minor banks surrounded by irregular slopes and a variety of biological assemblages adapted to live in the different types of habitats (Fig. 1). The bank appears therefore constituted by several subplanar terraces slightly elongated in the direction of Punta Licosa. The less deep terrace is first covered by extended Posidonia meadows and by populations of photophilous algae (Cystoseira spp.) and, downward, by sand ripples and megaripples which alternate with shelf coralligenous banks hosting populations of hemiphotophilous algae (Halimeda tuna). The deepest bank is covered by coarse sands and sometimes by fine gravels, deriving from the dismantling of coralligenous bioconstructions, locally covered by remnants of Posidonia oceanica meadows. The slope which surrounds and separates the terraces is slightly inclined. It is characterized by coralligenous structures
more or less covered by organogenic sands. The southern side of the area is more heterogeneous, interrupted by channels of organogenic sands flows and buttresses of shelf coralligenous. In its upper part, the slope is characterized by marked megaripples and dunes and is colonized by ascidians (Rhopalaea neapolitana) and by hoary urchins (Sphaerechinus granularis), whereas in its lower part “praline” fields of melobesia are common. They alternate with shelf coralligenous banks, which are densely populated by echiurids (Bonellia viridis). Along the northern side of the area, the slope is enriched in the muddy component and is characterized by dense populations of pencil urchins (Stylocidaris affinis). The deep terrace forms a sub-horizontal structure at the foot of the slope, covered by terrigenous muds mixed with bioclasts, colonized by bioturbating organisms, particularly fossorious polychaetes and crustaceans. The submerged beach environment can be subdivided into a submerged beach and a beach foot. This latter is a gentle slope constituted by muddy sands, colonized by fauna living both at the surface and inside the sediment (molluscs, polychaetes, isopods, anisopods, amphipods, decapods, echinoderms), which constitutes the main food for sea turtles (Caretta caretta) and for juvenile specimens of numerous fish species.
Fig. 1 – Detail of the map at 1:30,000 scale. 1 – Bank; 2 - Slope; 3 – Coralligenous buttresses; 4 – Terrace.
