Daniele Ventura

Feeding ecology of some fish species occurring in artisanal fishery of Socotra Island (Yemen).

The demersal species Lethrinus borbonicus, Lethrinus mahsena, Lethrinus microdon, Lethrinus nebulosus, Lutjanus bohar, Lutjanus gibbus, Lutjanus kasmira, Epinephelus fasciatus, Epinephelus stoliczkae, Carangoides gymnostethus and Euthynnus affinis are important coastal fishes species of the northern coast of Socotra (Yemen), exploited by local fishery. The biology and feeding ecology of these species are poorly known in the area. A total of 1239 specimens were sampled from the main fishing landing site of the island (Hadibo). Total length and weight were measured, stomach contents were analyzed, diet overlap, Fultons Condition index, and trophic levels were estimated. C. gymnostethus, L. microdon and L. kasmira occupied the highest position (T=4.50), L. nebulosus occupied the lower one (TL=3.41). The role of the increasing abundance of small pelagic fish in the diet of many species after the upwelling event is evident, but also different feeding strategies are reported, according to fish ecology.

Mapping and Classification of Ecologically Sensitive Marine Habitats Using Unmanned Aerial Vehicle (UAV) Imagery and Object-Based Image Analysis (OBIA)

Nowadays, emerging technologies, such as long-range transmitters, increasingly miniaturized components for positioning, and enhanced imaging sensors, have led to an upsurge in the availability of new ecological applications for remote sensing based on unmanned aerial vehicles (UAVs), sometimes referred to as “drones”. In fact, structure-from-motion (SfM) photogrammetry coupled with imagery acquired by UAVs offers a rapid and inexpensive tool to produce high-resolution orthomosaics, giving ecologists a new way for responsive, timely, and cost-effective monitoring of ecological processes. Here, we adopted a lightweight quadcopter as an aerial survey tool and object-based image analysis (OBIA) workflow to demonstrate the strength of such methods in producing very high spatial resolution maps of sensitive marine habitats. Therefore, three different coastal environments were mapped using the autonomous flight capability of a lightweight UAV equipped with a fully stabilized consumer-grade RGB digital camera. In particular we investigated a Posidonia oceanica seagrass meadow, a rocky coast with nurseries for juvenile fish, and two sandy areas showing biogenic reefs of Sabelleria alveolata. We adopted, for the first time, UAV-based raster thematic maps of these key coastal habitats, produced after OBIA classification, as a new method for fine-scale, low-cost, and time saving characterization of sensitive marine environments which may lead to a more effective and efficient monitoring and management of natural resources.

Sabellaria reefs as reservoirs of preferential species: the case of Eulalia ornata Saint-Joseph, 1888 (Annelida: Phyllodocidae)

Sabellaria alveolata is a widespread coastal engineer species that builds sandy bioconstructions in coastal marine habitats, which host a rich associated fauna. Some of these associated species are quite common on rocky or sandy substrates, but few taxa are strictly linked to Sabellaria reefs. In this study, we report, for the first time, the phyllodocid worm Eulalia ornata in the Tyrrhenian Sea and highlight its high-fidelity link with S. alveolata bioconstructions. Despite being included in the European Red List of Habitats, little is known about Sabellaria reefs, their associated fauna and their ecological role in the Mediterranean Sea. For these reasons, studies aiming at improving our knowledge of S. alveolata reefs and their associated fauna can be regarded as an important step towards more appropriate management plans for sensitive coastal habitats.

Cleaning interactions between the cleaner wrasse Symphodus melanocercus (Osteichthyes: Labridae) and brown meagre Sciaena umbra (Osteichthyes: Sciaenidae)

Cleaning interactions between the wrasse Symphodus melanocercus and brown meagre Sciaena umbra are documented from observations whilst free diving on a shallow rocky reef in the central Mediterranean Sea. Cleaning events occurred at cleaning stations mainly during the morning and gradually decreased in the evening. The body parts mostly cleaned were the opercular region and the fins, possibly as gnathiid isopods preferentially attach to these areas.