Cymatium corrugatum (Lamarck 1816) gastropoda,prosobranchia. A new species for the Adriatic

Very valuable papers concerning malacology of the Adriatic Sea deal, for the most part, with the systematics, whereas there is a substantial number of papers with very scarce information on the ecology of individual species. Since I intended to provide some more comprehensive data on individual species, rather complex bionomic and biocoenological research was undertaken aiming to study the taxonomy and the ecology of the Prosobranchiata group. Present research covered different biotopes of the northern, middle and southern Adriatic, both in the shallow coastal and deeper open littoral, and hard and mobile bottoms. Material was collected in two ways: 1) Scuba diving or direct collection and observations; and 2) an indirect method of collection of samples by Petersen grab, dredge and trawl. Throughout years of investigations of the coastal and open Adriatic, the species Cymatium corrugatum has been recorded only in the vicinity of the Vis and Hvar islands, at 60 and 80 m depths. It was found in the biocoenosis of detritic bottoms of the open sea and biocoenosis of coastal detritic bottoms. Cymatium corrugatum is a new species for the Adriatic and therefore it should be included in the register of the Gastropod fauna of the Adriatic Sea.     

Observations on the Spatio-Temporal Distribution of Crustacean Amphipods in the Fusaro Coastal Lagoon (Central Tyrrhenian Sea, Italy) and Some Notes on Their Presence in Mediterranean Lagoons

Abstract. The amphipod population of the Fusaro coastal lagoon (Tyrrhenian Sea, Italy) was studied on a spatial-temporal scale. During a one-year period, samples were collected on hard and soft bottoms along a transect from the inland to the seaward side of the lagoon. Thirteen species were identified. The dominant taxa included species typical of lagoon environments, such as Corophium insidiosum and Microdeutopus gryllotalpa , and species typical of marine environments yet also inhabiting sheltered or semi-closed areas, such as Corophium acutum, Ericthonius brasiliensis , and Elasmopus rapax.
An inner-outer gradient was not evident, while a seasonal pattern was recognizable. At the community level, clear differences between the two substrata were not evident because of high algal growth and organogenic detritus on the soft bottoms. The importance of hydrodynamic forces in a euhaline lagoon in selecting amphipod communities - characterized by a typical trophic behaviour and way of life – is discussed. Information on the ecology of the collected species and a list of Mediterranean lagoons where they are present are also provided.     

Macroalgal assemblages of disturbed coastal detritic bottoms subject to invasive species

Characteristic flora and fauna that are highly sensitive to disturbances colonize coastal detritic bottoms in the Mediterranean Sea. In the present study, a comparison of the assemblage composition and colonization by invasive macroalgae was made between two coastal detritic macrophyte assemblages, one dominated by rhodoliths (free-living non-geniculate Corallinales) and the other dominated by fleshy algae, in an area that has been exposed to important levels of anthropogenic disturbance, mainly pollution (including changed sedimentation regimes) in the recent past (bay of Marseilles, France). In comparison with less strongly impacted Mediterranean regions, the macrophyte assemblages in the bay of Marseilles were characteristic in terms of species identity and richness of coastal detritic macrophyte assemblages. However, extremely low species abundance (cover) was observed. As far as invasive species were concerned, Caulerpa racemosa var. cylindracea was only abundant in the rhodolith assemblage whereas the two invasive Rhodophyta Asparagopsis armata and Womersleyella setacea were mainly found in the fleshy algae assemblage. The seasonality observed in the Rhodolith assemblage seemed to be related to the development of C. racemosa var. cylindracea and did not follow the typical pattern of other Mediterranean assemblages. This study represents the first study of coastal detritic assemblages invaded by C. racemosa var. cylindracea.     

Habitat preferences and life history of the red scorpion fish, Scorpaena notata, in the Mediterranean

Scorpaena notata is a small, sedentary scorpaenid species widely distributed in the Mediterranean and adjacent waters of the Atlantic. In the western Mediterranean it inhabits coastal continental shelf bottoms. In the Balearic Islands, these bottoms are characterised by the presence of the facies with red algae, including both Peyssonnelia and mäerl beds. These beds enhance the structural complexity, biodiversity and secondary production of the soft bottoms. Due to the oceanographic conditions of the Islands, the facies with red algae are especially rich in terms of biomass and algal coverage, and are widespread distributed between 40 and 90 m depth, where trawlers exploiting the continental shelf operate. The present work studies the biology of S. notata and its relationship with habitat characteristics. Special attention is focused on the aspects related to fish condition and growth as a tool to assess the importance of the facies with red algae for fish.     

Benthic Communities of the lnfralittoral in the N. Sporades (Aegean Sea): a Variety of Biotopes Encountered and Analysed

Abstract. The infralittoral benthos was studied on three islands of the Northern Sporades in the Aegean Sea. Thirteen stations were sampled on both hard and soft substrata and 408 taxa were identified, some of zoogeographical interest. Multivariate statistical methods such as classification, ordination and Similarilies Terms Analysis were combined with existing ecological information to delineate the various communities present and to point to the indicator species characterising them. The communities were then defined using the indicator species and their affinities to typical biocoenoses. The main factor responsible for the observed distribution proved to be the type of substratum (algal cover or sediment type), which reflects the light and hydrodynamic conditions. The observed bathynietric zonation was similar lo that of the Balearic Islands in the western Mediterranean.     

A Map of the Posidonia oceanica Beds of Marina ďElbu (Corsica, Mediterranean)

Abstract. A large-scale map of the Posidonia oceanica seagrass beds as well as other benthic substrata and communities was compiled for a cove of a marine reserve free from pollution and man-made disturbance. An extensive diving survey of the cove and the interpretation of aerial colour photographs were used. The greater part of the cove is occupied by the P. oceanica meadow. Patches of dead "matte" were observed at a depth of between 7 and 14 m. They may be the result of a natural hydrodynamic equilibrium between building and erosion.     

A critical analysis on the response of macroinvertebrate communities along disturbance gradients: description of MEDOCC (MEDiterranean OCCidental) index

Macroinvertebrate communities inhabiting shallow sandy bottoms from Catalonia and Balearic Islands coastal waters (Western Mediterranean) were used to develop the Mediterranean Occidental (MEDOCC) index, a new methodology to assess the ecological status (ES) according to Water Framework Directive (WFD) requirements. The dominance pattern of four ecological groups (EG; sensitive, indifferent, tolerant and opportunistic organisms) was studied along a disturbance gradient. Sensitive taxa were present in disturbed situations and tolerant species were related to opportunistic taxa. The thresholds between ES were scaled according to the shifts in the dominance pattern of the EGs. The distribution of the EGs along the gradient of disturbance may vary depending on the studied communities, thus influencing the boundaries defining the ES. With the development of the MEDOCC index it is shown that analysing the response of the communities to the increasing gradient of disturbance is critical to enable an accurate proposal for boundary setting to be made, and to improve the applicability of the indices. AMBI (AZTI Marine Biotic Index), Bentix (Biotic Index), and MEDOCC indices were applied to the dataset to compare the ES obtained.     

Succession and seasonal onset of colonization in subtidal hard‐bottom communities off northern Chile

Although there is extensive information concerning the colonization sequences of benthic communities, little is known about the successional development of subtidal hard‐bottom habitats in highly productive coastal upwelling areas. In these systems, succession is predicted to be fast due to high growth rate of the later dominant colonizers. Using artificial hard substrata a field experiment was conducted in a rocky subtidal area off Northern Chile (Humboldt Current System) and monitored at 3‐month intervals to test the following hypotheses: (i) epibenthic succession may proceed through consecutive replacement of species, (ii) there is a fast convergence rate towards natural communities, and (iii) different seasonal starting points for the colonization will produce different community structure over a 1‐year period of exposure. Panels were installed on a vertical wall at 17 m water depth. Three replicate panels were sampled every 3 months over a period of 27 months. As a reference, six haphazardly selected plots from the surrounding natural community were surveyed at each sampling date. To evaluate how seasonally varying substratum availability affects community development, further panels were exposed for a 12‐month period, starting in four different seasons (n = 3 replicates per season). Community succession was slow and occurred through progressive changes, between early encrusting red corallines, middle Balanus flosculus and late Lagenicella variabilis. After 27 months, the community composition, but not its structure, was similar between experimental and reference communities on surrounding rocky bottoms. Seasonality had no effects and after 1 year of exposure the experimental communities converged towards a common structure. This study indicates that succession of subtidal epibenthic communities follows a slow and predictable pattern with a dominant late colonial species. In addition, aseasonal variability might be more relevant during colonization and succession in this upwelling ecosystem.     

Sublittoral seaweed communities on natural and artificial substrata in a high-latitude coral community in South Africa

Coral mortality may result in macroalgal proliferation or a phase shift into an alga-dominated state. Subtidal, high-latitude western Indian Ocean coral communities at Sodwana Bay on the KwaZulu-Natal coast, South Africa, have experienced some mortality because of warm-water anomalies, storms and other causes, but the response of the macroalgae is unknown. We investigated the abundance and diversity of benthic algae on different hard natural substrata (dead digitate, brain and plate corals and beach rock) on Two-Mile Reef, Sodwana Bay. We also compared algal communities colonising ceramic, marble and pretreated ceramic tiles placed on the reef for six months. We identified 95 algae (14 Chlorophyta, 11 Phaeophyceae, 69 Rhodophyta and one cyanobacterium). Assemblages on natural and artificial substrata were dominated by the brown alga Lobophora variegata (Lamouroux) Womersley ex Oliveira and non-geniculate corallines (Rhodophyta, Corallinaceae). Cluster and ordination analyses revealed that the algae showed no affinity for particular substrata, whether natural or artificial. Algal cover was occasionally higher on rougher tiles and crustose corallines were significantly more abundant on marble than ceramic tiles. Two-Mile Reef had 23.1% dead and 48.4% live scleractinian coral cover, where dead corals were colonised indiscriminately by many small algal species, but there was no evidence of algal proliferation. The results provide a baseline for monitoring this high-latitude reef system.     

Long-term change in the structure of a Posidonia oceanica landscape and its reference for a monitoring plan

Abstract On the basis of a detailed cartographic survey carried out by Side Scan Sonar and a towed underwater video camera during 2005, and from a series of historical maps (1959, 1980, 1990), an extensive regression of Posidonia oceanica (L.) Delile beds was evidenced for a vast area of the central Tyrrhenian Sea (Latium coast, Italy). The total loss of P. oceanica surface was assessed through GIS estimate. In 1959, the Posidonia beds extended over 7290 ha, while in the 2005 survey they had regressed to 2899 ha, a loss of about 60% of their coverage. Also the seagrass lower limit showed a general depth decrease in time. Total seagrass coverage loss and lower limit regression were not uniform along the whole investigated areas and three main sub-areas have been identified with different degrees of regression somehow related with coastal potential human-mediated impacts. From different coverage estimates of the present survey and of the previous maps, minimum sampling areas were calculated through bootstrapping simulation routines from small sampling areas (Landscape Units) to reach the nearest estimate of the observed condition in the different periods.     

Distribution of green algal mats throughout shallow soft bottoms of the Swedish Skagerrak archipelago in relation to nutrient sources and wave exposure

Distribution and biomass of green algal mats were studied in marine shallow (0–1 m) soft-bottom areas on the Swedish west coast from 1994 to 1996, by combining aerial photography surveys with ground truth sampling. Filamentous green algae, dominated by species of the genera Cladophora and Enteromorpha, were generally present throughout the study area during July and August, and largely absent in late April and early May. These algae occurred at 60 to 90% of the locations investigated during the summer, and were estimated to cover between 30 and 50% of the total area of shallow soft bottoms of the Swedish Skagerrak archipelago. The distributional patterns were similar during the three years of the investigation and appeared unrelated to annual local nutrient inputs from point sources and river discharge. We postulate that the apparent lack of such a relationship is due to an altered state of nutrient dynamics throughout the archipelago. Mechanisms are likely to involve long-term, diffuse elevations in nutrient levels in coastal waters of the Skagerrak and the Kattegat over several decades leading to current eutrophic conditions, exceeding nutrient requirements for abundant filamentous algal growth. Patterns of algal abundance in our study were largely related to physical factors such as exposure to wind, waves and water exchange under conditions where nutrient loads among embayments seemed to be unlimited. Further, our results show that sediments covered by algal mats had higher carbon and nitrogen contents than unvegetated sediments. We hypothesise that sustained high nutrient loads, manifested in extensive biomass of filamentous algae during summer months, are re-mineralised via decay and sedimentation in the benthic realm. Hence, accumulated carbon and nutrients in the sediment could, in turn, constitute the basic pool for future algal mat production overlying soft bottoms in areas where tidal exchange is limited.     

The Deep-Water Peyssonnelia Beds from the Balearic Islands (Western Mediterranean)

Abstract. Peyssonnelia bed distribution on continental shelf bottoms of the Balearic Islands (Western Mediterranean) ranges from 40 to 90 m depth. Different species of Peyssonnelia dominate these bottoms and, according to multivariate techniques, two main assemblages have been distinguished: the Peyssonnelia rosa-marina beds and the Peyssonnelia sp. beds, together with some transition samples between Peyssonnelia and maërl beds. Erect red algae are always abundant. Although average yearly irradiance reaching these beds is only 6.4-0.3% of subsurface irradiance, the species richness averages 45 species per sample (1600 cm²) and mean biomass is 2835 g dw. m^-2. The high carbonate content of the living algae of these bottoms suggests that they are important contributors to the production of sediments in the Balearic continental shelf.     

Short-term variation in copepod community and physical environment in the waters adjacent to the Kuroshio Current

A continuous survey examined short-term variations in the zooplankton community and physical ocean environment from the northeastern Izu Islands to Boso Peninsula in Japan. High copepod abundance and small upwellings in the surface layer and salinity minimum layer in the subsurface were observed on the north side of coastal fronts in the westernmost transect, moving southward as the Kuroshio Current left the Boso Peninsula. Thus, the salinity minimum layer might be a key factor forming upwelling and the fronts, leading to large abundance of coastal copepods off the northeastern Izu Islands. A community structure analysis of calanoid copepods revealed an intermediate belt assemblage between coastal and offshore (Kuroshio) assemblages. Copepod abundance was remarkably low and Ctenocalanus vanus dominated (nearly 37%) in the intermediate belt zone, indicating that C. vanus has a relatively high tolerance to adverse environments for calanoid copepods. As the Kuroshio Current left the Boso Peninsula, the coastal assemblage expanded in the same direction, and the intermediate belt assemblage off the northeastern Izu Islands disappeared. The largest population of Calanus sinicus was found along the two western transects off the northeastern Izu Islands (>1000 m depth), which was assumed to be transported from Sagami Bay and advanced southwestward while growing from copepodite stages CIII to CV. Larvae of C. sinicus would be an important food for fish larvae in addition to Paracalanus parvus s.l., the numerically dominant species in the coastal assemblage, and C. vanus under the adverse conditions for coastal copepods.     

Megabenthic ecology of the deep Faroe–Shetland channel: A photographic study

The megabenthic ecology of the cold water (<0 °C) area of the Faroe–Shetland Channel was investigated using an off-bottom towed camera platform WASP (wide angle seabed photography). A series of 10 photographic transects, approximately evenly spaced along the channel axis, were studied. Photographic transects allowed quantitative benthic diversity data to be obtained from this understudied yet commercially important area for oil and gas exploration. The sedimentary characteristics of the seabed changed dramatically from a region of ice-rafted boulders and gravel in the southwest to fine sediments more typical of the deep sea to the northeast. Despite the relatively low species richness of the megabenthos, variation in faunal composition with depth was apparent. Two distinct “communities” were identified, one in the south of the channel and the other in the north. Epibenthic megafaunal communities in the south were dominated by suspension and filter feeders and in the north by deposit feeders. Diversity and standing stock of megabenthos decreased to the northeast of the channel. Lebensspuren number and areal cover increased northwards in the Channel. The increase in bioturbation and deposit feeder abundance was concurrent with an increase in fine sediment quantity.     

The macrozoobenthos of the Karavasta lagoon system (Albania): local assemblages and geographical comparisons

The macrozoobenthic assemblage from the Karavasta lagoon system, the main wetland of Albania, was studied on soft bottoms and artificial hard substrates. Three different communities were identified: the typical ‘brackish‐water community’, an ‘outlet community’ dominated by filter‐feeders, and a typical ‘marine community’, inhabiting fine sandy bottoms, where polychaetes are dominant, together with a few species of tunicates and bivalves, which colonize hard substrates. The occurrence of build‐ups of the bryozoan Conopeum seurati, settled on the upper portion of long submerged wooden poles, was the main feature of faunistic interest. The faunistic affinity between the zoobenthic assemblage recorded in the hyperhaline lagoon of Karavasta and the assemblages from two Italian lagoons, the brackish Lake of Lesina and the euhaline Lake of Fogliano, was considered according to the different hydrological conditions and the geographical location. Hydrological confinement and salinity were likely to be the leading factors influencing the benthic community composition in the Karavasta wetland area. Therefore, on a vaster spatial scale, the isolation and geographical proximity of the ecosystems and colonizing ability and dispersal changes of the species appear to be the main factors liable to produce faunal variations.     

Spatio-Temporal Distribution of Algal and Animal Communities in a Posidonia oceanica Meadow

Abstract. Investigations were carried out in a Posidonia oceanica meadow at Ischia (Gulf of Naples) along a depth gradient from 1 to 32 m in November 1979 and May 1981.
In these two months, different discontinuities were found at the sampling stations (1, 5, 10, 20, 30 m) at 10 m for leaf features, between 1 and 5 m for the algal community and the vagile fauna. The leaf features (length, surface, and biomass) along the transects show a delay in leaf production toward the deeper stations, below the thermocline.
The algal community shows in both seasons and in all stations a persistence of an encrusting layer, mostly represented by Corallinaceae and the brown alga Myrionema orbiculare , while at the shallowest station (1 m) the community is characterized by a more developed upright layer.
The vagile fauna of the leaf stratum, mostly represented by Polychaeta, Mollusca , and Crustacea (Peracarida and Decapoda) , shows a consistent zonation in both seasons along the transect. A superficial community at I m, characterized by a low number of species and individuals and specialized for high environmental energy levels, and a deeper community, persistent in time and more strictly related to the Posidonia oceanica meadows, are identified.
The influence of environmental factors and the importance of meadow structure for the zonation of the algal and animal communities are discussed.     

Effects of the suspension feeding mussel Mytilus trossulus on a brackish water macroalgal and associated invertebrate community

The importance of suspension-feeding mussels is particularly apparent in benthic communities; however, the role of this feeding strategy on the development of macroalgal and associated invertebrate communities is in general poorly known. The effect of suspension-feeding mussels Mytilus trossulus on benthic communities was studied in an in situ factorial field experiment in the Northern Baltic Sea over one ice-free season. The experiment was performed under different regimes of wave exposure (low and moderate) and on different sedimentary habitats (soft bottom with high organic content, soft bottom with low organic content, and hard bottom). In general the presence of mussels was associated with increased biomass of filamentous algae, herbivores and deposit feeders and decreased biomass of charophytes. The effect of M. trossulus interacted with the effect of exposure and substrate. Stronger responses were observed in moderately exposed than in sheltered areas. The presence of M. trossulus affected charophytes and deposit feeders on sand with low content of organic matter and filamentous algae on pebbles but not on other substrate types. The magnitude of the effects varied between months. The results suggest that (i) even in dynamic coastal systems the biodeposits and excretions of mussels are at least partly assimilated locally and are not flushed away to the open sea, (ii) the accumulation of faecal material induced elevated growth of deposit feeders, (iii) mussels enhanced the growth of ephemeral macroalgae and reduced the growth of perennial macroalgae, and (iv) together with increasing benthic primary production, mussels indirectly increase the production of herbivores.     

Polychaete Depth Distribution in a Posidonia oceanica Bed (Rhizome and Matte Strata) and Neighbouring Soft and Hard Bottoms

Abstract. The study was carried out in a Posidonia oceanica bed and in the neighbouring sandy and rocky bottoms, at Ponza Island (Central Tyrrhenian Sea), in order to investigate the distributional pattern of the polychaete community at different depths. A total of 15232 individuals of polychaetes belonging to 218 species was collected and three new species of Syllidae were found. The polychaete community of the matte can be clearly distinguished from the neighbouring communities; this is due to the high species richness in Posidonia , which is related to the heterogeneity of the biotope. In the Posidonia bed the shallow stations (1 m and 5 m depth) were the richest in terms of species numbers and individuals due to the high shoot density of the seagrass bed. In the shallow waters polychaete community structure changed according to the different exposure to water movement. Rocky bottom species, which preferentially inhabit crevices, were more abundant in the matte exposed to water movement (5–10 m depth). In contrast, soft-bottom species were more abundant in the sheltered zone (1 m depth) as well as in the deeper zone due to the reduction of the Posidonia bed.     

Habitat and Microhabitat of Mediterranean Clingfishes (Teleostei: Gobiesociformes: Gobiesocidae)

Abstract. This study addresses the habitat and microhabitat of the seven species of gobiesocid fish in the Mediterranean Sea. It is shown that Lepadogaster lepadogaster is closely adapted to large pebbles and boulder fields of rounded stones with a smooth surface. L. candollei is more euryecious and, in addition to inhabiting boulder fields also, occurs close to seagrass meadows, in small cavities and in association with sea urchins. Diplecogaster bimaculata is also euryecious and extends to greater depths. It lives on sand and muddy bottoms as well as on coralline grounds. At some locations this species is found in high abundance during the spawning season under empty bivalve shells or flat stones. Apletodon dentatus is the rarest species of Gobiesocidae in the Mediterranean Sea. It has a close association with seagrass or large brown algae ( Cystoseira ). Juveniles of A. incognitus are either associated with sea urchins or inhabit Posidonia meadows. Adults prefer the vicinity of seagrass meadows under empty bivalve shells and stones overgrown with red algae. Gouania wildenowi is stenoecious and is restricted to the interstices of roundish coarse gravel near the waterline. Opeatogenys gracilis is also stenoecious and lives only on the leaves of Posidonia and Cymodocea seagrass. The colourations of the different species and their variations are described and discussed.     

Implementation of the European Water Framework Directive: Natural variability associated with the CARLIT method on the rocky shores of the Ligurian Sea (Italy)

The Water Framework Directive (WFD) 2000/60/EC, adopted by the European Community in 2000 with the goal of maintaining and improving the aquatic environments, requires that member states achieve and maintain a good ecological status of all water bodies by 2015. In the marine context, the ecological status has to be quantified applying indexes based on appropriate key biological elements, which allow the categorization of water bodies into five Ecological Status (ES) classes. The CARLIT index is a cartographic monitoring tool enabling the Ecological Quality Ratio (EQR) to be calculated using macroalgae in coastal hard bottoms as a key biological element; at present it is being applied in Spain, France and Italy. To detect actual changes of water quality and, consequently, rely on the application of indexes for the assessment of the ecological status in the marine environment, it is necessary to evaluate their sensitivity to natural variability at different temporal and spatial scales. In this study we present a first quantification of natural (spatial and temporal) variability of EQR‐CARLIT quality assessment in 2006 and 2007 along the Ligurian coast (North‐Western Mediterranean, Italy). The EQR‐CARLIT values recorded along the Ligurian coastline show that natural variability of EQR‐CARLIT is low and that it does not affect the attribution of a given stretch of coast to a particular ES class, in agreement with the major human pressures acting in the area (urbanization, river load, sea‐farming). A small‐scale variability was detected, strengthening the use of cartography of the whole rocky shore, whenever possible, or, alternatively, the assessment of the ecological status for long stretches of coast, to encompass the small‐scale variability due to local factors.