Giovanni Chimienti

Seafloor integrity of the Mar Piccolo Basin (Southern Italy): quantifying anthropogenic impact

ABSTRACT The Mar Piccolo Basin is a coastal brackish marine ecosystem located along the northern coast of the Gulf of Taranto (Southern Italy). Despite the ecological relevance of the area (Site of Community Importance IT9130004, Regional Reserve ‘Palude La Vela’ EUAP1189), the entire basin is subjected to intensive human usage. The main activities include extensive mussel farming, important industrial activities, a military harbor and densely populated shores. The goal of our study was to spatially quantify human pressure within the basin and its relationship with biocoenoses. A broad set of data was integrated including acoustic remote data (obtained using a multibeam echosounder and side scan sonar devices), direct observations obtained by SCUBA diving and from a trawled camera, an orthophoto and ESRI® Imagery Basemap. At least eight categories of anthropogenic infrastructure and marks of past and present-day human activities were identified within the Mar Piccolo Basin water column and on the seafloor. These included line farms, pole farms, breeding frame structures, anchoring scars, excavations, buoys, wrecks and undefined traces. Each category was mapped and described using morphometric characterization. The integration of all available data allowed the production of an original map providing the Mar Piccolo seafloor disturbance by anthropogenic impact and an updated distribution of benthic communities, showing their spatial relation. Through the production of a specific thematic map, our work provides the first quantitative assessment of the extent and density of the identified human impact in order to evaluate seafloor integrity.

Know the distribution to assess the changes: Mediterranean cold-water coral bioconstructions

Cold-water corals (CWCs) are the main engineers of extensive deep coral frameworks hosting a lush diversity of species in certain areas of the world, including the Mediterranean Sea. In this basin, the most important bioconstructor species are the so-called “white corals”, i.e. the colonial scleractinians Madrepora oculata and Lophelia pertusa as well as the solitary coral Desmophyllum dianthus. Anthropogenic impacts (e.g., fishing pressure) and human-induced changes (e.g., rising temperatures and ocean acidification) are known to affect these important deep-sea bioconstructors. The present paper provides an overview of the horizontal and vertical distribution of white corals in the Mediterranean Sea. The knowledge of the present distribution of living CWCs represents a crucial baseline to understand how anthropogenic and natural changes are affecting these deep Mediterranean habitats.

Isidella elongata (Cnidaria: Alcyonacea) facies in the western Mediterranean Sea: Visual surveys and descriptions of its ecological role

Abstract Isidella elongata is a candelabrum-shaped alcyonacean forming important facies on the bathyal muddy bottoms of the Mediterranean Sea, currently considered a sensitive habitat and heavily impacted by deep-sea fisheries. Until a few decades ago, this facies was a widespread habitat of the deep Mediterranean seabed and I. elongata was a common species in the trawling fishery’s bycatch. Despite its current persistence in dense aggregations being very scarce, a dense facies of I. elongata was revealed during several ROV (Remotely Operated Vehicle) surveys carried out from 2010 to 2014 on the muddy bottoms between two seamounts east of Ibiza (Balearic Sea). The facies developed in an area between 480 and 615 m in depth where trawling is forbidden, with an extraordinary density of about 2300–2683 colonies/ha, representing one of the biggest facies of I. elongata currently known for the Mediterranean Sea considering the surface covered and the colonies’ density. The associated community was surveyed, with 50 taxa identified. Moreover, a canyon southwest of Formentera characterised by the presence of I. elongata together with a high trawling impact was investigated. The density of the colonies was 53–62 colonies/ha and only 19 taxa of associated fauna were observed. The results of the two areas are compared and discussed in the framework of the protection of such an important habitat.

The rediscovery of Rosalinda incrustans (Cnidaria: Hydrozoa) in the Mediterranean Sea

Abstract The present note reports a new record of Rosalinda incrustans (Cnidaria: Hydrozoa) since its last reliable record in the Mediterranean Sea in 1958. Several colonies were recorded on the spider crab Anamathia rissoana off the Balearic Islands. The taxonomic history of R. incrustans, considered a putatively extinct species in a recent paper, is reviewed.

Withdrawal behaviour of the red sea pen Pennatula rubra (Cnidaria: Pennatulacea)

Abstract Aggregations of sea pens are important soft-bottom communities providing a three-dimensional complexity from which several associated species can benefit. The red sea pen Pennatula rubra is one of the Mediterranean coastal field-forming sea pens able to establish dense aggregations on the sandy/muddy bottoms of the infra- and circumlittoral zones. This species was first described at the end of the 17th century, but since then little information has been published about its biology, ecology and biogeography. Even less is known about its behaviour, its reactions after disturbance and its possible escape strategies. Several species of pennatulaceans can withdraw partially or completely into the sediment, usually in a fast (i.e. a few seconds) process of polyp closure and expulsion of part of the water contained within the colony. The present study reports and discusses the withdrawal behaviour of P. rubra after disturbance. This behaviour has never been documented before in this species. It proved to be a slow process requiring between 210 and 340 seconds (3 min 30 sec to 5 min 40 sec) for the complete withdrawal. Moreover, a soft bioluminescence was observed in two undisturbed colonies in the study area, while two other colonies were found to be out of the sediment, inflating themselves with seawater and getting carried by currents as a sort of dispersal behaviour.

Mediterranean Bioconstructions Along the Italian Coast

Marine bioconstructions are biodiversity-rich, three-dimensional biogenic structures, regulating key ecological functions of benthic ecosystems worldwide. Tropical coral reefs are outstanding for their beauty, diversity and complexity, but analogous types of bioconstructions are also present in temperate seas. The main bioconstructions in the Mediterranean Sea are represented by coralligenous formations, vermetid reefs, deep-sea cold-water corals, Lithophyllum byssoides trottoirs, coral banks formed by the shallow-water corals Cladocora caespitosa or Astroides calycularis, and sabellariid or serpulid worm reefs. Bioconstructions change the morphological and chemicophysical features of primary substrates and create new habitats for a large variety of organisms, playing pivotal roles in ecosystem functioning. In spite of their importance, Mediterranean bioconstructions have not received the same attention that tropical coral reefs have, and the knowledge of their biology, ecology and distribution is still fragmentary. All existing data about the spatial distribution of Italian bioconstructions have been collected, together with information about their growth patterns, dynamics and connectivity. The degradation of these habitats as a consequence of anthropogenic pressures (pollution, organic enrichment, fishery, coastal development, direct physical disturbance), climate change and the spread of invasive species was also investigated. The study of bioconstructions requires a holistic approach leading to a better understanding of their ecology and the application of more insightful management and conservation measures at basin scale, within ecologically coherent units based on connectivity: the cells of ecosystem functioning.