Aggressive behavior of bottlenose dolphins (Tursiops truncatus) towards conspecifics is widely described, but they have also often been reported attacking and killing harbour porpoises (Phocoena ...phocoena) around the world. However, very few reports exist of aggressive interactions between bottlenose dolphins and other cetacean species. Here, we provide the first evidence that bottlenose dolphins in the western Mediterranean exhibit aggressive behavior towards both striped dolphins (Stenella coeruleoalba) and Risso's dolphins (Grampus griseus). Necropsies and visual examination of stranded striped (14) and Risso's (2) dolphins showed numerous lesions (external rake marks and different bone fractures or internal organ damage by blunt trauma). Indicatively, these lessons matched the inter-tooth distance and features of bottlenose dolphins. In all instances, these traumatic interactions were presumed to be the leading cause of the death. We discuss how habitat changes, dietary shifts, and/or human colonization of marine areas may be promoting these interactions.
Whale lice (Cyamidae) are ectoparasitic amphipods exclusive to cetaceans. Data on their epidemiology usually come from species infecting baleen whales, which are large, slow‐moving hosts. In this ...study, we provide data on infection parameters, population structure and microhabitat selection in a whale louse exclusive to delphinids, Syncyamus aequus, with the aim of comparing them with those from cyamid species from large whales. A total of 176 striped dolphins Stenella coeruleoalba stranded along the Mediterranean coast of Spain during 1980–2016 were examined. The prevalence of S. aequus was 27.3% (95% CI: 20.9–34.3), and populations were sparse, with a mean number of whale lice per infected host of just 4.5 (3.4–6.7). The parasites were found on the head, with a clearly nested pattern, with the blowhole being the most frequently occupied site, followed by the mouth corner and eyes. Single‐male or single‐female populations were found on as much as 39.6% of infected dolphins. The sex ratio did not significantly depart from 1:1. Females were significantly larger than males and exhibited low fecundity (<10 eggs). The sex or the age class of the dolphins did not significantly affect the abundance or population structure of S. aequus. The patterns here obtained are in sharp contrast with those reported for whale lice infecting large whales. The small, streamlined body of dolphins creates strong current flows that would restrict the amount of suitable microhabitats and the body size of their associated cyamids. This would limit population growth, which in turn would lower the chances of host‐to‐host transmission upon body contacts, as well as male competition for the access to females.
We studied the infection parameters, population structure and microhabitat selection of the whale louse Syncyamus aequus, exclusive to delphinids. The data were obtained from stranded striped dolphins, Stenella coeruleoalba, from the Western Mediterranean. The small, streamlined bodies of dolphins create strong current flows that would restrict the amount of suitable microhabitats for the parasite and might impose constraints on their size and population growth. This, in turn, could influence key aspects such as sex ratio, reproductive potential or sexual dimorphism in S. aequus.
The colonisation of new suitable habitats is crucial for species survival at evolutionary scale under changing environmental conditions. However, colonisation potential may be limited by philopatry ...that facilitates exploiting successful habitats across generations. We examine the mechanisms of long distance dispersal of the philopatric loggerhead sea turtle (Caretta caretta) by analysing 40 sporadic nesting events in the western Mediterranean. The analysis of a fragment of the mitochondrial DNA and 7 microsatellites of 121 samples from 18 of these nesting events revealed that these nests were colonising events associated with juveniles from distant populations feeding in nearby foraging grounds. Considering the temperature-dependent sex determination of the species, we simulated the effect of the incubation temperature and propagule pressure on a potential colonisation scenario. Our results indicated that colonisation will succeed if warm temperature conditions, already existing in some of the beaches in the area, extend to the whole western Mediterranean. We hypothesize that the sporadic nesting events in developmental foraging grounds may be a mechanism to overcome philopatry limitations thus increasing the dispersal capabilities of the species and the adaptability to changing environments. Sporadic nesting in the western Mediterranean can be viewed as potential new populations in a scenario of rising temperatures.
Coastal waters of the Valencia region are important habitats for bottlenose dolphins, but also important fishing grounds for artisanal fisheries. No studies have been carried out here to investigate ...the overlap and interactions between the fishing grounds and dolphin habitat. The present study aims to assess the potential occurrence of interactions between artisanal fisheries and bottlenose dolphins in these waters. Face to face interviews were conducted to investigate for the first time artisanal fishermen's perceptions of their interactions with bottlenose dolphins.
A total of 131 fishermen (40.1% of the artisanal fleet for the Valencia region) participated of research. Among the interviewed fishermen, 86.1% perceived that dolphins damaged fishing gear as they attempted to feed, and they also detected significant direct damage to fish. Of all fishermen reporting a negative interaction with bottlenose dolphins, 76.3% also reported financial loss (2907.1 ± 2512.7 €/year (100–12,000). Despite the high level of interaction with dolphins reported, fishermen do not consider bycatch to be an important threat for bottlenose dolphins. Our results show geographical differences in fishermen's perceptions of damage caused by dolphins: while dolphins were considered to be the second cause of economic loss in the southernmost ports, fishermen from the northern ports considered interaction with bottom trawl boats to be more harmful than interaction with dolphins. The more intense interaction reported by fishermen in fishing ports in the southern study area may be associated with higher presence of bottlenose dolphin in these zones. Our study provides a useful insight into fishermen's perceptions of interaction between bottlenose dolphins and artisanal fisheries in this key area for the species in the western Mediterranean Sea. It also highlights the need for future work including direct observations of interactions and damage to gather reliable data to assess the need for conservation measures.
•Artisanal fisheries fishing grounds and bottlenose dolphin habitat overlap in Valencia region.•Fishermen claim that dolphins cause damage that entails economic loss.•Fishermen does not perceive bycatch as a negative aspect of fisheries on bottlenose dolphin.•Differences in interaction perception among ports seems related to dolphin distribution.•Future direct measures are necessary to validate fishermen perceptions previous to any management implementation.
The colonisation of new suitable habitats is crucial for species survival at evolutionary scale under changing environmental conditions. However, colonisation potential may be limited by philopatry ...that facilitates exploiting successful habitats across generations. We examine the mechanisms of long distance dispersal of the philopatric loggerhead sea turtle ( Caretta caretta ) by analysing 40 sporadic nesting events in the western Mediterranean. The analysis of a fragment of the mitochondrial DNA and 7 microsatellites of 121 samples from 18 of these nesting events revealed that these nests were colonising events associated with juveniles from distant populations feeding in nearby foraging grounds. Considering the temperature-dependent sex determination of the species, we simulated the effect of the incubation temperature and propagule pressure on a potential colonisation scenario. Our results indicated that colonisation will succeed if warm temperature conditions, already existing in some of the beaches in the area, extend to the whole western Mediterranean. We hypothesize that the sporadic nesting events in developmental foraging grounds may be a mechanism to overcome philopatry limitations thus increasing the dispersal capabilities of the species and the adaptability to changing environments. Sporadic nesting in the western Mediterranean can be viewed as potential new populations in a scenario of rising temperatures
We present a detailed analysis of sea turtle strandings (n = 619) over a 14 yr period (1993 to 2006) from the Valencian Community (eastern Spain). Loggerhead turtles Caretta caretta accounted for ...98.1% of recorded strandings. Although we detected an increasing trend in the annual number of strandings over the study period, we expect that this was driven primarily by the increase in detection effort. Loggerhead turtles were mainly juveniles (mean cSD curved carapace length from notch to tip CCL = 53.6 c 12.6; range: 16 to 80.2 cm, n = 312) and strandings were far more frequent in summer months (69.6% June to September). We believe that interaction with longline fisheries was by far the main cause of observed stranding (>28% of all cases, 43.5% of 393 turtles with likely mortality cause identified). Turtles showing signs of interaction with longlines were, on average, larger (CCL = 57.5 c 10.4; range: 29.8 to 80.2 cm, n = 116) than turtles stranded due to other causes (CCL = 51.4 c 13.3; range: 16 to 79 cm, n = 196; t -test: t = -4.49, p < 0.001) and were more frequent in summer months, when longline fishing effort off the coast was highest. Recent reductions in longline effort may have led to a decrease in recent years in the proportion of stranded turtles with evidence of longline interaction. Although inferences from stranding data must be subject to a number of caveats, when considered over wide spatio-temporal extents and in conjunction with other data sources, they can offer useful insights into the geographic ranges, seasonal distribution and life history of marine species of conservation concern.
We report the first confirmed occurrence of a Lepidochelys olivacea in the Mediterranean Sea based on the study of an individual stranded on a beach, located in the town of Oropesa del Mar ...(40º05ʹ32ʺN, 0º08ʹ02ʺE), Castellón province, East Spain, in May 2014. Morphological and genetic analyses were used to confirm the identification of the species. The individual had a sequence that matched the 470 bp Lepidochelys olivacea haplotype F (Genbank accession number: AF051773), found in several Atlantic populations. This becomes one of the northernmost known occurrences of olive ridleys in the world and is the first reports of this species in the Mediterranean Sea.
Nearly 50% of human malignancies exhibit unregulated RAS-ERK signaling; inhibiting it is a valid strategy for antineoplastic intervention. Upon activation, ERK dimerize, which is essential for ERK ...extranuclear, but not for nuclear, signaling. Here, we describe a small molecule inhibitor for ERK dimerization that, without affecting ERK phosphorylation, forestalls tumorigenesis driven by RAS-ERK pathway oncogenes. This compound is unaffected by resistance mechanisms that hamper classical RAS-ERK pathway inhibitors. Thus, ERK dimerization inhibitors provide the proof of principle for two understudied concepts in cancer therapy: (1) the blockade of sub-localization-specific sub-signals, rather than total signals, as a means of impeding oncogenic RAS-ERK signaling and (2) targeting regulatory protein-protein interactions, rather than catalytic activities, as an approach for producing effective antitumor agents.
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•DEL-22379 inhibits ERK dimerization without affecting its phosphorylation.•DEL-22379 blocks proliferation of tumor cells harboring RAS-ERK pathway oncogenes.•In animal tumor models, DEL-22379 induces apoptosis, preventing tumor progression.•DEL-22379 is unaffected by resistance mechanisms that hamper BRAF/MEK inhibitors.
Herrero et al. identify a small molecule inhibitor of ERK dimerization that impedes the growth of tumor cells dependent on a hyperactivated RAS-ERK pathway. Importantly, the antitumor effect of this compound in cells is not affected by the reported resistance mechanisms for the current BRAF and MEK inhibitors.
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