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 resource

Identification and characterization of nursery areas of red mullet Mullus barbatus in the Central Tyrrhenian Sea

Red Mullet Mullus barbatus is an important target of fishing activities in the central Tyrrhenian Sea, so it is essential to identify its critical habitats in order to manage this resource efficiently. Our research specifically focused on the identification and characterization of nursery areas. The use of spatial interpolation techniques enabled us to identify five nurseries that were highly persistent through time. Moreover, the estimate of juvenile density confirmed the strong aggregation effect of these nursery grounds, as a great portion of young individuals were concentrated in a relatively small surface of the study area. The environmental characterization of these areas showed that juveniles were mainly distributed on bottoms with a relatively high percentage of sand (>70%; P <0.05). Shannon biodiversity index analysis indicated that the southern nurseries reached the highest values of habitat quality (P < 0.0001). Multivariate analysis showed that nursery grounds were divided into three main groups, and analysis of spatial dynamics showed that two different strategies characterized Red Mullet juveniles when density changes over time. In particular, in some areas young individuals selected habitats in a density-dependent way following the basin model scheme, while in other zones they selected habitats in a density-independent way according to the proportional density model. Results also showed that juveniles followed the proportional density model strategy into nursery areas with the highest Shannon biodiversity index values

Colonization and disappearance of Mytilus galloprovincialis Lam. on an artificial habitat in the Mediterranean Sea

A Mytilus galloprovincialis population, settled on a new artificial habitat at 12 m depth in the Central Tyrrhenian Sea, was investigated for 10 years. The new substratum, located at a depth lower than the preferential range of the species, was colonized temporarily by mussels which reached very high densities and dominated the benthic community from their colonization until the third year. The length-frequency distribution analysis showed a progressively complex population structure with up to three cohorts. The yearly recruitments were observed once a year in spring. The growth curve provided a maximum length higher than that reported for shallow waters. Nevertheless, the gregarious habits of mussels and the reduced water movement caused edaphic modifications of the substratum, which was covered progressively by sediments and biodeposits (pseudofaeces). Consequently, the population structure was affected by a reduction of the newly recruited cohorts, and mussels disappeared after 5 years of colonization. This may be explained by the reduction in the substratum available for the first settlement (hydroid covering), as well as by the modification of the surface required for final settlement. (C) 1996 Academic Press Limite

Metabolic Activity of Human Chorionic Gonadotropin (hCG) on Glycemia and Leptinemia in Experimental Animals Fed a Cafeteria Diet

Objectives: To elucidate the relationship of hCG administration to glycemia, Non Esterified Fatty Acids (NEFA), leptin and adiponectin levels on experimental animals previously submitted to a cafeteria diet, and then to a Low Calorie Diet (LCD). Design: Forty-one rats were selected (21 females, 20 males) and divided into seven (0-6) groups. Animals from groups 1 to 6 were fed a &#x22;cafeteria diet&#x22; with a mean energy content of 10% protein, 30% carbohydrate and 60% fat. Animals from group 0 were fed the standard laboratory diet. After the fattening period, animals from groups 1 to 6 were submitted to a restricted diet consisting of one-third the average daily intake for rats. hCG was administered for five weeks according to a specific protocol. The effects of hCG treatment were evaluated using analysis of variance (ANOVA). Results: These assessments were compared: (1) glycemia, adiponectins, leptins and non-esterified fatty acids (NEFA); (2) weight; (3) formulation effect; and (4) dose effect. Differences in leptins were observed between the Control group and Injectable A (p=0.026), Intrarectal Suspension A (p=0.20), Intrarectal Suspension B (p&#x3c;0.001), and Intrarectal Suspension C (p&#x3c;0001) groups. In all cases, the average values were higher for the control group. Significant differences were found in the groups treated with Injectable B, Intrarectal Suspension B (p=0.025) and Intrarectal Suspension C (p=0.037). Groups receiving Intrarectal Suspension B or C showed significantly lower mean leptin values. Differences in glycemia were detected between the Control group and Intrarectal Suspension A (p=0.021) and Intrarectal Suspension B (p=0.020) groups. Groups treated with Intrarectal Suspension A or B showed lower mean blood glucose values. Conclusions: Results show the activity of hCG (both urinary and recombinant) on glycemia and leptins levels in experimental animals in different formulations.hCG administration significantly decreased blood sugar and leptin levels, whereas adiponectins were only relatively sensitive to hCG

Colonization of transplanted Posidonia oceanica. Understanding the spatial dynamics through high-spatial resolution underwater photomosaics

Following the restoration of a Posidonia oceanica meadow impacted by theConcordia shipwreck, we investigated the spatial dynamic of the most important andprotected Mediterranean endemic seagrass over a two-year period applying three spatialmetrics: number of patches, mean patch size and total cover. By means of underwaterphotomosaics, we noticed a diminution in the number of patches in favour of the mean sizeand total cover. The outcomes showed that, under suitable environmental conditions,P. oceanica colonizes rapidly the dead matte substrate. This study underlines the importanceof considering the spatial dynamic of transplanted seagrasses in monitoring programmes andgives new insights on the progression rate of transplanted P. oceanica

Patrón reproductivo y características de la población de la salema, Sarpa salpa (Osteichthyes: Sparidae) en el mar Mediterráneo

The sexual maturation and the growth of the salema, Sarpa salpa (Linnaeus, 1758), along the Italian Mediterranean coast (central Italy), were studied in fish (n = 105) killed incidentally by underwater explosions during the construction of Civitavecchia harbour in 1999 and specimens collected with trammel nets (n = 339). This species is characterized by a protandric hermaphroditism and the sex change process occurs between 24 and 31 cm TL corresponding to a wide range of ages (3-7 years). Size at maturity (L50) was 19.5 cm, at which almost all the individuals were males. Two distinct spawning periods were observed: one in spring, from March to May, and the other in autumn, from the end of September to November. During the first year, compensatory growth occurred in the individuals born in the two periods. An annual regular pattern of ring deposition was identified in the otoliths: the translucent ring was laid down during the winter months, while the opaque ring was formed during the summer months. Back-calculated lengths at age were used to estimate the parameters of the Von Bertalanffy growth equation which were: L∞ = 37.27 cm, K = 0.27 year-1 and t0 = -0.53 year. Salema showed isometric growth (b = 3.04; P = 0.84; t = 0.19).La maduración sexual y crecimiento de Sarpa salpa (Linnaeus, 1758) en las costas del Mediterráneo italiano (Italia central) fueron estudiadas a partir de la recolecta de ejemplares muertos accidentalmente (n = 105) como consecuencia de las explosiones submarinas acaecidas durante la construcción del puerto de Civitavecchia en 1999, así como de ejemplares recolectados mediante redes de arrastre (n = 339). Esta especie se caracteriza por un hermafroditismo protándrico, ocurriendo el proceso de cambio sexual entre los 24 y 31 cm TL, los cuales corresponden a un amplio rango de edades (3-7 años). La talla de maduración (L50) fue de 19,5 cm, siendo la casi la totalidad de los individuos eran de sexo masculino. Se observaron dos períodos diferentes de reproducción: uno en primavera, de marzo a mayo y otro en otoño, de finales de septiembre a noviembre. Se observó, durante el primer año, un crecimiento compensatorio ocurrido entre los individuos nacidos en los dos períodos. Se identificó en los otolitos un modelo anual y regular de deposición de anillos. Se observó el depósito de un anillo translúcido durante los meses invernales, mientras que otro opaco se formó durante los meses de verano. Las composición por edades y tallas retrocalculadas se utilizaron para estimar los parámetros de la ecuación de crecimiento de Von Bertalanffy, es decir: L∞ = 37,27 cm, K = 0,27 año-1 y t0 = -0,53 año. S. salpa demostró un crecimiento isométrico (b = 3,04; P = 0,84; t = 0,19)

Double trouble. Synergy between habitat loss and the spread of the alien species Caulerpa cylindracea (Sonder) in three Mediterranean habitats

The role of habitat degradation on the spread of the alien green alga Caulerpa cylindracea is reported here by comparing observations achieved through a multi-year assessment on three Mediterraneans habitats, namely Posidonia oceanica meadows, Phyllophora crispa turf, and coralligenous reefs. Due to the peculiarity of the study site, both natural-reference and impacted conditions were investigated. C. cylindracea occurred in all the studied habitats under impacted conditions. High susceptibility to the invasion characterized impacted P. oceanica, where Caulerpa cover reached 70.0% in summer months. C. cylindracea cover did not differ significantly among conditions in P. crispa turf, where values never exceeded 5.0%. Conversely, the invasive green algae was low in abundance and patchily distributed in coralligenous reefs. Our results confirmed that habitat loss enhances the spread of C. cylindracea, although with different magnitudes among habitats. Dead matte areas of P. oceanica represented the most vulnerable habitat among those analyzed, whereas coralligenous reefs were less susceptible to the invasion under both the studied conditions

Feeding habits of European hake (Merluccius merluccius) in the central Mediterranean Sea

European hake (Merluccius merluccius) is an important predator of deeper shelf-upper slope Mediterranean communities. It is a nectobenthic species distributed over a wide depth range (20−1000 m) throughout the Mediterranean Sea and the north east Atlantic region (Fisher et al., 1987). Notwithstanding the ecological and economic importance (Oliver and Massutí, 1995) of hake in the Mediterranean, many aspects of its biology (e.g., recruitment and reproduction), due to multiple spawning (Sarano, 1986) and the current state of exploitation, are poorly understood (Arneri and Morales-Nin, 2000)

Analysis of demersal assemblages off the Tuscany and Latium coasts (north-western Mediterranean)

A four-year time series (1994-1997) of groundfish trawl surveys performed within the European Union Project "MEDITS" (Mediterranean International Trawl Surveys), was analysed to identify and describe the fish assemblages along the continental shelf and slope of Tuscany and Latium (Italy), in the north-western Mediterranean. Cluster analysis was used to group samples with similar species composition in terms of abundance, biomass and frequency of occurrence. Results allowed the identification of four to five broad assemblages along the depth gradient: a strictly coastal group (< 50 m depth), two groups in the upper and lower part of the continental shelf (essentially 50-200 m), an epibathyal group (200450 m) and a group derived from hauls made at depths greater than 450 in. Each assemblage corresponded to a faunistic association with relatively homogeneous and persistent species composition, biomass and density indices

Characterization and cartography of some Mediterranean soft-bottom benthic communities (Ligurian Sea, Italy)

Soft-bottom benthic communities were studied along the Western coast of the Ligurian Sea with a new approach using both videocamera surveys and collected samples. The preliminary distribution of soft-bottoms and the definition of the limits and status of seagrass beds were carried out in September 1991, using an underwater vehicle provided with a videocamera and towed by a boat. Moreover, 90 benthic samples were collected at 5-40 m depth in order to characterize the macrobenthic soft-bottom communities. Six soft-bottom benthic assemblages and two sea grass biotopes (Cymodocea nodosa and Posidonia oceanica) were revealed by means of underwater images and multivariate analysis (TWINSPAN) on samples collected. The communities inhabiting the infralittoral sandy and coarse sediments corresponded to those previously described in the Mediterranean Sea, whereas a large complex transition between sandy and muddy communities was recognized on circalittoral soft-bottoms. Information obtained with this approach was used to draw a map of the investigated areas at 1:10,000 scale. The employment of the two techniques was cost effective for both time and research effort