Silvestro Greco

Deep Coral Oases in the South Tyrrhenian Sea

A Mediterranean “roche du large” ecosystem, represented by four rocky shoals, located a few miles apart on a muddy bottom at 70–130 m depth in the gulf of St. Eufemia (Calabria, South Tyrrhenian Sea), was studied by means of Remotely Operated Vehicle (ROV) photo imaging. The shoals host highly diversified coral communities, mainly composed of arborescent colonies of gorgonians (Callogorgia verticillata, Paramuricea clavata, Paramuricea macrospina, Bebryce mollis, Villogorgia bebrycoides, Corallium rubrum, and Leptogorgia sarmentosa), and antipatharians (Antipathella subpinnata, Antipathes dichotoma and Parantipathes larix). The coral colonies reach high densities (up to ca. 17 colonies m−2) and large sizes, such as the over 1.5 m wide antipatharian colonies. We hypothesized that the abundance and composition of the coral assemblages differed significantly among the rocky shoals and with respect to the surrounding soft bottoms. Various environmental variables were tested as possible explanatory factors of the observed differences. Moreover, due to their off-coast localization, we report here that these unique ecosystems are potentially subjected to a strong pressure from the local fishing activities, which were tentatively characterized. The recorded coral β-diversity among the shoals supports the hypothesis that these habitats behave like small oases of hard substrata interspersed in a muddy bottom. Because of their intrinsic beauty and rarity and their biological and ecological value, we stress the need of specific actions aimed at the urgent protection of these oases of biodiversity.

Distribution and abundance of postlarval and juvenile Pleuragramma antarcticum (Pisces, Nototheniidae) off Terra Nova Bay (Ross Sea, Antarctica)

Abstract During the Italian Antarctic Expedition of 1987–1988 zooplankton was collected in Terra Nova Bay (Ross Sea) by a multinet BIONESS (250-μm or 500-μm net mesh size). The early life history of Pleuragramma antarcticum was described from 268 samples. More than 98% of a total of 34,436 fish larvae belonged to P. antarcticum. The mean relative abundance in the whole area for positive 0 to 150-m hauls was 434 ind./100 m3 (±720 SD). Postlarvae were most abundant and frequent in the samples (99.8%) while low concentrations of juveniles were found (n=67). Length of age group 0 ranged from 8 to 20 mm and age group 1+ were from 36 to 53 mm. Average growth rate over a period of 1 year was 0.08 mm per day. Based on modal values, the mean daily increment of P. antarcticum postlarvae in the period 5 January to 2 February (29 days) was about 0.21 mm. Highest abundances occurred near Cape Washington (mean: 2,108 ind./100 m3) while lower densities were recorded in the northern basin of the self (31 ind./100 m3). Horizontal and vertical distribution patterns in Terra Nova Bay seem to be strictly correlated to hydrographic features and different water masses with highest densities associated with the westward flowing current of the limb of the Antarctic coastal current and southern limb of the Ross Sea Gyre. These currents become part of the clockwise gyre in Terra Nova Bay. More than 62% of the postlarvae were collected in well-stratified warm surface water (0–50 m) near the summertime thermocline (20–70 m). The northern part of Terra Nova Bay seems to represent nursery ground of early stages of P. antarcticum and the presence of permanent polynya could provide favourable food conditions for development of the first stages of life. Differing distribution patterns probably reflect an interaction of various parameters including bathymetry, floating ice shelf, hydrographic features such as currents, local eddies and frontal systems, with P. antarcticum postlarval biology (spawning) and ecology (feeding, horizontal and vertical distribution patterns).

The first identified winter feeding ground of fin whales (Balaenoptera physalus) in the Mediterranean Sea

The presence of ¢n whales in the Mediterranean Sea has been documented since ancient times. In spite of this, reliable information on their ecology and distribution is limited to the north-western part of the basin. Recent genetic studies have demonstrated that Mediterranean ¢n whales comprise a separate population with very limited gene £ow with their North Atlantic co-speci¢cs. Although both published and anecdotal information reports their presence in the south central Mediterranean during winter, there is no information on habitat use. In February 2004, a 14-day boat survey was carried out in the waters surrounding the island of Lampedusa, where ¢n whales occur at this time of the year. A total of 20 ¢n whale groups (average group size two animals) were encountered. In each encounter the animals were engaged in surface feeding activity. From plankton samples and underwater video, the prey species was identi¢ed as the Euphausiid, Nyctiphanes couchi. The information obtained suggests that this area may be an important winter feeding ground for ¢n whales. The results represent signi¢cant new information on ¢n whale ecology in the Mediterranean, with associated conservation and management implications.

Ichthyoplankton abundance and distribution in the Ross Sea during 1987–1996

Abstract. During Italian expeditions, ichthyoplankton was collected in the Ross Sea and Terra Nova Bay, by BIONESS and Hamburg Plankton Net (250-µm and 500-µm mesh, respectively). A total of 394,453 fish larvae representing 46 species, 27 genera and 9 families were collected. Pleuragramma antarcticum dominated during three of the four cruises, whilst in 1994/1995 Trematomus lepidorhinus was also abundant. The most abundant icefish was Chionodraco myersi, which co-occurred with P. antarcticum. Macrouridae, Myctophidae and Bathylagidae were oceanic. Paralepididae occurred in all areas. Notothenioids, nearly 100% of the catch, occurred close to the coast and dominated the shelf ichthyoplankton community.

Implementing and Innovating Marine Monitoring Approaches for Assessing Marine Environmental Status

Marine environmental monitoring has tended to focus on site-specific methods of investigation. These traditional methods have low spatial and temporal resolution and are relatively labor intensive per unit area/time that they cover. To implement the Marine Strategy Framework Directive (MSFD), European Member States are required to improve marine monitoring and design monitoring networks. This can be achieved by developing and testing innovative and cost-effective monitoring systems, as well as indicators of environmental status. Here, we present several recently developed methodologies and technologies to improve marine biodiversity indicators and monitoring methods. The innovative tools are discussed concerning the technologies presently utilized as well as the advantages and disadvantages of their use in routine monitoring. In particular, the present analysis focuses on: (i) molecular approaches, including microarray, Real Time quantitative PCR (qPCR), and metagenetic (metabarcoding) tools; (ii) optical (remote) sensing and acoustic methods; and (iii) in situ monitoring instruments. We also discuss their applications in marine monitoring within the MSFD through the analysis of case studies in order to evaluate their potential utilization in future routine marine monitoring. We show that these recently-developed technologies can present clear advantages in accuracy, efficiency and cost.

The Coastal Fish Fauna of Terra Nova Bay, Ross Sea, Antarctica

The coastal fish community of Terra Nova Bay (Ross Sea) was studied from samples collected off the Italian Antarctic station Terra Nova Bay down to about 700 m depth from 1987 to 1995. Species composition, abundance and vertical distribution are reported and the biological characteristics such as feeding habits, reproduction, age and growth of the common species have been studied. Twenty-six fish species were recorded, the most common being the nototheniid Trematomus bernacchii and the channichthyid Chionodraco hamatus. As for the vertical distribution of fish, species diversity was higher in shallow than in deep waters. The fish community comprises species which exhibit three different trophic niches: T. bernacchii and Trematomus pennellii are mostly benthos feeders, Trematomus hansoni and Trematomus loennbergi are mostly piscivorous and Trematomus newnesi feeds preferentially on plankton. Differences in reproductive strategies have been found during the sampling period, i.e. January and February, when C. hamatus and T. hansoni were in a spawning condition, whereas T. bernacchii was in a resting-early development stage. The two most common species, T. bernacchii and C. hamatus, show a high longevity, living more than 20 and 10 years, respectively. Moreover, in both species the females attain slightly older age and grow faster than males.

Summer distribution and abundance of larval and juvenile fishes in the western Ross Sea

Ichthyoplankton samples were collected during the November–December 1994 Italian Antarctic Oceanographic Cruise carried out to the western Ross Sea. A midwater trawl (Hamburg Plankton Net) was used to collect samples at 26 stations. Larval and juvenile specimens of 21 species belonging to six families (Artedidraconidae, Bathydraconidae, Channichthyidae, Macrouridae, Nototheniidae and Paralepididae) were caught from surface to 380 m depth. Mean relative abundance of larval fish in the whole area was about 2.7 specimens 1000 m −3 of filtered water. Pleuragramma antarcticum were the most abundant as postlarvae and juveniles. Larval and postlarval specimens of Chionodraco myersi were also abundant and widespread. The high number of Trematomus lepidorhinus (570 larvae) found in a single station off Terra Nova Bay (74°48′75“S, 164°36′90”E) was noteworthy. Our data demonstrate that the species diversity of the larval fish community in the western Ross Sea is much as found elsewhere in the Antarctic and show a greater abundance of fish larvae in inshore than in offshore waters.

An insight into the status of the striped dolphins, Stenella coeruleoalba , of the southern Tyrrhenian Sea

Drift-nets are known to result in high incidental catches of some cetacean species. Despite a UN moratorium on their use in the high seas and a ban in the Mediterranean by all European Union countries, including Italy (EC Reg. 1239/98), some fisheries continue to operate illegally. In 2002 and 2003 three line-transect surveys were conducted in the southern Tyrrhenian Sea around the Aeolian archipelago. These transects were designed to assess the presence, distribution and population size of cetacean species likely to be affected by accidental captures in this area. Data were only sufficient to estimate abundance for the striped dolphin. The best estimate (and first such estimate for this area) was 4030 individuals (CV=0.30, 95% CI=2239-7253) for May 2003. A rough estimate of striped dolphin by-catch, based on floating carcases, was calculated as 36 by-caught animals over a period of 12 days (CV=0.58, 95% CI=11-113). These results, although approximate, are a cause for concern. Conservation and management implications of the results are discussed.

The population of Errina aspera (Hydrozoa: Stylasteridae) of the Messina Strait (Mediterranean Sea)

Errina aspera is the only species belonging to the family Stylasteridae known from the Mediterranean Sea. The distribution of this species includes the Messina Strait, the Gibraltar Strait and the Atlantic coast of Morocco. In spite of the taxonomic and biogeographical importance of this species, no studies were conducted on its population structure in the Messina Strait. Here we report a study carried out with the aid of a ROV on a horizontal transect 350 m long at a depth comprised between 8 3 and 105 m where an extremely dense population of this stylasterid (101.4 ± 13.3 m -2 ) was recorded. The main components of the benthic community other than E. aspera are the coralline alga Lithothamnion philippii and the white zoanthid Epizoanthus sp. The colonies of E. aspera have a height ranging between 1.2 and 18.8 cm ( 4 . 1 ± 0.1 cm on average); they generally show a bi-dimensional, fan shaped morphology, but three-dimensional, brush-like specimens are also observed. The size-frequency distribution of the colony height is unimodal with a mode in the classes of 3-5 cm and a long tail of rare large colonies suggesting that the current may act as a limiting factor for the colony growth. The association with the gastropod ovulid Pedicularia sicula is confirmed.

Spatial Distribution and Feeding Habits of Larval and Juvenile Pleuragramma Antarcticum in the Western Ross Sea (Antarctica)

During four spring-summer Italian Antarctic expeditions to Terra Nova Bay and the Western Ross Sea in 1988, 1989–90, 1994–95 and 1996, zooplankton and ichtyoplankton were collected by a multinet BIONESS (250 μm and 500 μm) and PHN (500 μm), respectively. Nototheniids were predominant in the whole study area, representing 97.3% of all larvae. Pleuragramma antarcticum was the dominant species sampled in the spring-summer cruises of 1987–88 (98.6%), 1989–90 (95.9%) and 1995–96 (99.8%), while it predominated in association with Trematomus lepidorhinus in 1994–95. The early life history of Pleuragramma antarcticum was described from 891 samples. Maximum abundances of P. antarcticum postlarvae were confined to Terra Nova Bay. The mean relative abundance in the whole area in summer 1988, for positive 0- to 150-m hauls, was 434 (±720 SD) specimens 100 m−3 and 158 (±212 SD) specimens per 100 m3 in January 1990 for positive 0-140-m hauls. Off Terra Nova Bay, postlarval abundance did not exceed 5-86 individuals 100 m−3. Juvenile Pleuragramma antarcticum showed a more oceanic occurrence than postlarvae of the same species. Low concentrations between 0.1 and 12.5 ind 100 m−3 (mean 1.66 ± 2.88 SD) were recorded in offshore waters between 170° and 175°E and in the southern part of Terra Nova Bay. Postlarvae (n = 4385) ranged between 7 and 23 mm SL (mean 13.9 ± 1.62 SD) and juveniles (n = 388) were between 28 and 53 mm SL (mean 40.0 ± 4.78 SD). A growth rate of 0.08 mm day−1 was confirmed for the first year. The daily increments of Pleuragramma antarcticum postlarvae estimated from sequential sampling in 1987–88 from Terra Nova Bay and in 1995–96 from the southern western Ross Sea were about 0.21–0.25 mm. The co-occurrence of different postlarval size classes during the investigations confirm that two hatching periods occurred in Terra Nova Bay between early and late December. The presence of early stages in January 1988, 1990 and 1996 (7–9 mm SL) confirms that Pleuragramma antarcticum spawn in Terra Nova Bay. Highest concentrations of postlarvae occurred at the edge near Cape Washington and in the inshore waters of Drygalski Ice Tongue. These areas seem to represent a nursery ground of early stages, where the presence of permanent polynyas could provide favourable food conditions for the development of the first stages of life. More than 62% of the postlarvae were collected in well-stratified Antarctic Surface Waters (AASW) with temperature values that exceed 0°C and vertical distribution appears to be related to the summertime thermocline. From these sites, early stages were drifted by a westward-flowing current of the limb of the Antarctic coastal current and the southern limb of the Ross Sea Gyre. These large gyres favoured postlarval retention mostly in northern and southern areas of Terra Nova Bay, preventing the drift north of Cape Washington, south of Drygalski Ice Tongue and in offshore waters beyond 170°E. Thus, the youngest planktonic stages of Pleuragramma antarcticum concentrate in the surface mixed layer of Terra Nova Bay where feeding conditions are favourable. In the size classes 8-17 mm the diet was dominated by calanoid eggs (35.5%), Limacina (32.1%) and tintinnids (17.6%). The cyclopoid copepod Oncaea curvata contributed to 7.1% of the diet.