Ecología trófica del delfín listado en aguas del Mar de Alborán y el Golfo de Cádiz

Existe muy poca información sobre la dieta del delfín listado (Stenella coeruleoalba) en aguas del sur de España. En este estudio se analizaron los estómagos de 61 delfines varados en Andalucía en los últimos ocho años (2007-2014). Diez estómagos estaban vacios y de los 51 individuos restantes, 35 vararon en la costa del Mar de Alborán y 11 en el Golfo de Cádiz. Para las 5 muestras restantes no se dispone de localidad concreta. Los restos de las presas en los estómagos consistieron sobre todo en estructuras duras: otolitos, cristalinos y unos pocos huesos de peces, así como mandíbulas y cristalinos de cefalópodos. No aparecieron otro tipo de restos lo que parece indicar que los individuos no se habían alimentado recientemente. Para caracterizar la dieta se calcularon tres índices (calculados para cada categoría de presa): frecuencia de aparición en los estómagos, número de individuos y peso reconstruido y sus porcentajes respectivos. El delfín listado parece ser una especie predominantemente piscívora (se identificaron restos de 5682 peces frente a solamente 210 cefalópodos) que se alimenta de especies mesopelágicas principalmente. La familia más importante tanto en número como en frecuencia de aparición fue Myctophidae, principalmente Ceratoscopelus maderensis y Myctophum punctatum a las que pertenecieron casi la mitad de los peces identificados (36,4%N, 35,3%F y 12,3%N, 25,5%F, respectivamente). También se identificó Maurolicus muelleri (Sternoptychidae 13,4%N y 17,6%F). Otras familias identificadas presentan una distribución más costera: Sparidae (Boops boops) y Carangidae (Trachurus sp.) (4,5%N, 9,8%F y 1,2%N, 3,9%F, respectivamente). Los cefalópodos identificados pertenecieron a 11 familias siendo la más abundante Ommastrephidae (26,7%N y 39,2%F). Otras familias incluyen representantes oceánicos, Brachioteuthidae (16,7%N y 21,5%F); Chiroteuthidae (6,7%N y 9,8%F); Enoploteuthidae (4,8%N y 3,9%F), Ancistrocheridae (0.5%N y 2%F) y otros de distribución más costera, Sepiolidae (19%N y 19,6%F), Sepiidae (5,7%N y 3,9%F) y Loliginidae (3,8%N y 5,9%F)

Plastic accumulation in the Mediterranean Sea

Concentrations of floating plastic were measured throughout the Mediterranean Sea to assess whether this basin can be regarded as a great accumulation region of plastic debris. We found that the average density of plastic (1 item per 4 m2), as well as its frequency of occurrence (100% of the sites sampled), are comparable to the accumulation zones described for the five subtropical ocean gyres. Plastic debris in the Mediterranean surface waters was dominated by millimeter-sized fragments, but showed a higher proportion of large plastic objects than that present in oceanic gyres, reflecting the closer connection with pollution sources. The accumulation of floating plastic in the Mediterranean Sea (between 1,000 and 3,000 tons) is likely related to the high human pressure together with the hydrodynamics of this semi-enclosed basin, with outflow mainly occurring through a deep water layer. Given the biological richness and concentration of economic activities in the Mediterranean Sea, the affects of plastic pollution on marine and human life are expected to be particularly frequent in this plastic accumulation region

Marine mammals and Good Environmental Status: Science, Policy and Society; Challenges and Opportunities

The Marine Strategy Framework Directive has become the key instrument for marine conservation in European seas. We review its implementation, focusing on cetacean biodiversity, using the examples of Spain and the Regional Seas Convention, OSPAR. The MSFD has been widely criticised for legal vagueness, lack of coordination, uncertainty about funding, and poor governance; its future role within EU Integrated Maritime Policy remains unclear. Nevertheless, the first stages of the process have run broadly to schedule: current status, environmental objectives and indicators have been described and the design of monitoring programmes is in progress, drawing on experience with other environmental legislation. The MSFD is now entering its critical phase, with lack of funding for monitoring, limited scope for management interventions, and uncertainty about how conservation objectives will be reconciled with the needs of other marine and maritime sectors, being among the main concerns. Clarity in governance, about the roles of the EU, Member States, Regional Seas Conventions and stakeholders, is needed to ensure success. However, even if (as seems likely) good environmental status cannot be achieved by 2020, significant steps will have been taken to place environmental sustainability centre-stage in the development of Integrated Maritime Policy for EU seas.Postprin

Sometimes Sperm Whales (Physeter macrocephalus) Cannot Find Their Way Back to the High Seas: A Multidisciplinary Study on a Mass Stranding

BACKGROUND: Mass strandings of sperm whales (Physeter macrocephalus) remain peculiar and rather unexplained events, which rarely occur in the Mediterranean Sea. Solar cycles and related changes in the geomagnetic field, variations in water temperature and weather conditions, coast geographical features and human activities have been proposed as possible causes. In December 2009, a pod of seven male sperm whales stranded along the Adriatic coast of Southern Italy. This is the sixth instance from 1555 in this basin. METHODOLOGY/PRINCIPAL FINDINGS: Complete necropsies were performed on three whales whose bodies were in good condition, carrying out on sampled tissues histopathology, virology, bacteriology, parasitology, and screening of veins looking for gas emboli. Furthermore, samples for age determination, genetic studies, gastric content evaluation, stable isotopes and toxicology were taken from all the seven specimens. The animals were part of the same group and determined by genetic and photo-identification to be part of the Mediterranean population. Causes of death did not include biological agents, or the "gas and fat embolic syndrome", associated with direct sonar exposure. Environmental pollutant tissue concentrations were relatively high, in particular organochlorinated xenobiotics. Gastric content and morphologic tissue examinations showed a prolonged starvation, which likely caused, at its turn, the mobilization of lipophilic contaminants from the adipose tissue. Chemical compounds subsequently entered the blood circulation and may have impaired immune and nervous functions. CONCLUSIONS/SIGNIFICANCE: A multi-factorial cause underlying this sperm whales' mass stranding is proposed herein based upon the results of postmortem investigations as well as of the detailed analyses of the geographical and historical background. The seven sperm whales took the same "wrong way" into the Adriatic Sea, a potentially dangerous trap for Mediterranean sperm whales. Seismic surveys should be also regarded as potential co-factors, even if no evidence of direct impact has been detected

Genetic differentiation among North Atlantic killer whale populations

Population genetic structure of North Atlantic killer whale samples was resolved from differences in allele frequencies of 17 microsatellite loci, mtDNA control region haplotype frequencies and for a subset of samples, using complete mitogenome sequences. Three significantly differentiated populations were identified. Differentiation based on microsatellite allele frequencies was greater between the two allopatric populations than between the two pairs of partially sympatric populations. Spatial clustering of individuals within each of these populations overlaps with the distribution of particular prey resources: herring, mackerel and tuna, which each population has been seen predating. Phylogenetic analyses using complete mitogenomes suggested two populations could have resulted from single founding events and subsequent matrilineal expansion. The third population, which was sampled at lower latitudes and lower density, consisted of maternal lineages from three highly divergent clades. Pairwise population differentiation was greater for estimates based on mtDNA control region haplotype frequencies than for estimates based on microsatellite allele frequencies, and there were no mitogenome haplotypes shared among populations. This suggests low or no female migration and that gene flow was primarily male mediated when populations spatially and temporally overlap. These results demonstrate that genetic differentiation can arise through resource specialization in the absence of physical barriers to gene flow. © 2010 Blackwell Publishing Ltd.Peer Reviewe

Differential space distribution of the genus Balaenoptera in the eastern tropical Atlantic Ocean

The main aim of this study was to improve knowledge regarding the spatial distribution of cetaceans (Balaenoptera spp.) using opportunistic sightings from purse seiners targeting tuna in tropical areas of the Atlantic Ocean (Atlantic, Eastern Central, FAO major fishing area 34) between January 2003 and December 2016. Each sighting datum collected by observers on board fishing vessels targeting tropical tuna was identified at the lowest possible taxonomic level. These data were analyzed using General Linear Models (GLMs) to determine the environmental variables that favor the preferential habitats of Balaenoptera spp. compared to those of other cetacean species. It was found that the sea surface temperature and sea-current velocity-component are factors that explain the differential spatial distribution of Balaenoptera spp. Thus, the probability of observing Balaenoptera spp. specimens in coastal areas is higher when temperatures are low and currents are slow. © 2020 Elsevier B.V.Universidad Autónoma de Chil