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Abstract

Plastic pollution is an omnipresent problem that threatens marine animals through ingestion and entanglement. Marine mammals are no exception to this rule but their interaction with plastic remains understudied in the Mediterranean Sea. Here we highlight this problem by analyzing the stomach contents of 34 individuals from seven odontocete species stranded in Greece. Macroplastic (>5 mm) was found in the stomachs of nine individuals from four species (harbour porpoise Phocoena phocoena, Risso's dolphin Grampus griseus, Cuvier's beaked whale Ziphius cavirostris and sperm whale Physeter macrocephalus) with the highest frequency of occurrence in sperm whales (60%). Gastric blockage from plastic was presumably lethal in three cases, with plastic bags being the most common finding (46%). Plastic ingestion is of particular conservation concern for the endangered Mediterranean sperm whales. A regular examination of stranded cetaceans with a standardised protocol is critical for allowing spatiotemporal comparisons within and across species.

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... The Globally, the visible evidence of interactions between marine mammals and marine litter are well documented (Lusher et al., 2018;Simmonds et al., 2012), although at local scale are still being carried out. Cetaceans usually forage at depth where direct observations of their feeding habits are notoriously complicated (Alexiadou et al., 2019). Thus, cetacean stranding presents a unique opportunity to obtain knowledge about feeding features and gastric content. ...
... Currently, the occurrence of plastics in the digestive contents of odontocete and mysticete species has been recorded (Alexiadou et al., 2019;Fossi et al., 2018). Data collated from worldwide strandings networks (sample sizes more than 10 animals), show high variation in rates of debris ingestion, ranging from 0% to a worryingly high 31% (Baulch and Perry et al., 2014). ...
... In that study, only 4 cetaceans of the 88 total stranded from the Catalonian coast in the period 2012−2019 were found to contain marine debris. In contrast, Alexiadou et al. (2019) examined 34 individuals of seven odontocete species stranded along the Greek coasts between 1993 and 2014, evidencing higher levels of debris ingestion (FO 26.5%) with 9 animals affected. Extremely worrying, in this last study, P. macrocephalus had the highest FO for plastic (FO 60%). ...
Conference Paper
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The presence of plastic in oceans is extremely worrying because it poses potential threats for marine organisms, including plastic entanglement and ingestion. In the present study, we examined the occurrence of marine debris in the gastrointestinal tract of 28 cetaceans: Stenella coeruleoalba (n=16), Tursiops truncatus (n=8), Grampus griseus (n=2), Balaenoptera physalus (n=1), Physeter macrocephalus (n=1) found stranded around the Balearic Sea. Three specimens (14.3 % of the sample) were found to have ingested plastic items, including fishing nets, plastic bags and strapping lines. The affected species were two adult females of T. truncatus and one juvenile male of P. macrocephalus. Average number of items was 3.3 ± 1.8 (mean ± SE) per individual. Moreover, the highest number of plastic items (n = 6), composed by one plastic bag, two transparent threats and three strapping lines, were recorded in the stomach of the P. macrocephalus, that most likely died due to stomach perforation. All plastic items were characterized by µ-Fourier Transform Infrared Spectroscopy. Polypropylene plastics represented 78.1% of the total number of plastic and were found in 85.2 % of the cetaceans sampled with plastic ingestion. As a conclusion, the occurrence of marine debris observed in this work confirms for the first time the impact of plastic pollution of cetaceans in the Balearic Sea.
... To date, plastic ingestion has been recorded in 81 marine mammal species [6][7][8][9], all seven sea turtle species [10][11][12], and 203 seabird species to date [13], and these numbers are still increasing [14]. In marine mammals, the ingestion of litter can occur either directly, when an animal mistakes an item for prey, or indirectly, through the consumption of prey that contains waste [15,16]. The effects of ingestion are diverse, depending on species, the type of material, the amount ingested, and location. ...
... The effects of ingestion are diverse, depending on species, the type of material, the amount ingested, and location. Debris in the forestomach can cause distention, obstruction, ulceration, perforation, and peritonitis, or they can functionally alter digestion, induce satiation, cause starvation, and general debilitation [8,15,[17][18][19]. Moreover, ingested litter can contribute to chemically induced harm through the bioaccumulation of pollutants contained or absorbed by the litter, such as plasticizers, chemical additives [20], absorbed persistent organic pollutants (POPs) [21], and heavy metals [22], many of which are known neurotoxins or endocrine disruptors [23]. ...
... Cetaceans usually forage at a depth where direct observations of their feeding habits are notoriously complicated [15]; thus, cetacean strandings present a unique opportunity to obtain knowledge concerning the feeding features and gastric content of these animals. Moreover, although this is an indirect method, the digestive content analysis of stranded cetaceans has been well-established for studying marine debris ingestion [9,25]. ...
Article
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The presence of plastic in oceans is extremely concerning as it poses a potential threat to marine organisms; for instance, they could become entangled in the plastic or they could ingest it. The objective of this work is to provide evidence, for the first time, of the impact that plastic debris has on stranded cetaceans in the Balearic Islands, in terms of ingestion and entanglement. We examined the occurrence of marine debris in the gastrointestinal tracts of 30 cetaceans, from five different species, that were found stranded around the Balearic Sea: Stenella coeruleoalba, Tursiops truncatus, Grampus griseus, Balaenoptera physalus, and Physeter macrocephalus. Three specimens (10% of the sample) were found to have ingested plastic items, including fishing nets, plastic bags, and strapping lines. The species affected were T. truncatus, and P. macrocephalus. Moreover, a total of seven cases of entanglement were recorded during the study, affecting four different species (S. coeruleoalba, T. truncatus, P. macrocephalus, and Megaptera novaeangliae), and all of them were entangled in discarded fishing nets. When possible, plastics were characterised by size, shape, colour, and polymer type. We concluded that the occurrence of marine debris observed in this work confirms the impact of plastic pollution on cetaceans in the Balearic Sea for the first time.
... Incidental ingestion may also occur more commonly where visibility is poor, such as in turbid water. For example, some of the highest known loads of ingested plastic in vertebrate megafauna come from the sperm whale, Physeter macrocephalus, (Alexiadou et al., 2019;De Stephanis et al., 2013;Jacobsen et al., 2010) a species that forages by suction in the deep ocean where light does not penetrate, precluding visual foraging. ...
... The dangers of plastic ingestion to the health of animals have been known since the 1950s, where captive marine animals at aquariums and oceanariums often died from swallowing indigestible foreign material (Walker and Coe, 1989). Wildlife deaths due to eating plastic litter have been recorded among cetaceans, pinnipeds, marine reptiles (predominantly sea turtles) and (marine) birds (Alexiadou et al., 2019;Wilcox et al., 2018;Roman et al., 2019a). Though there is less evidence for the deaths of freshwater species than their marine counterparts as a direct result of plastic ingestion, the gastrointestinal physiology is similar between freshwater and marine animals of the same taxa, and we propose that the risk of death is comparable given similar exposure to analogous items. ...
... Numerous studies indicated that the ingestion of plastic (Alexiadou et al., 2019;Bearzi et al., 2011;Byard et al., 2020;Coombs et al., 2019;Denuncio et al., 2011;Fernandez et al., 2009;Puig-Lozano et al., 2018a), fishing-related debris (Alexiadou et al., 2019;Byard et al., 2020;Denuncio et al., 2011;Fernandez et al., 2009) and entanglement in fishing gear (Panti et al., 2019) occur among dolphins. Dolphins are highly intelligent, and we do not expect ingestion and entanglement to result from most encounters, so we have scored the interaction risk for ingestion and entanglement as "Moderate". ...
Article
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Plastic litter is a pollutant of aquatic environments worldwide, with some of the world's highest litter densities occurring in freshwater ecosystems. Little information about the risk that plastic litter poses to aquatic wildlife is available across the world's most polluted waterways. To help assess the risk to aquatic species where empirical data is lacking, our review presents i) a risk assessment methodology for predicting plastic litter impacts on aquatic wildlife in data poor environments, ii) a case study demonstrating this risk assessment methodology for wildlife across two heavily polluted river basins in Asia, the Mekong and Ganges River Basins; and iii) a broad review summarising common trends in litter interactions and risk to freshwater fish, aquatic birds, cetaceans and raptors. This risk analysis unites a systematic review approach with risk matrices following International Standards Organization's risk assessment criteria, evaluating the risk of plastic entanglement and ingestion and the potential for harm to the animal. In the Mekong and Ganges River Basins, we found that the risk of litter entanglement is higher than litter ingestion. Four species were forecast to be at high risk of entanglement: Ganges River dolphin, Gharial, Mekong giant catfish and Irrawaddy dolphin. The eastern imperial eagle and greater spotted eagle were noted to be at moderate risk of entanglement. Both the Ganges River dolphin and Irrawaddy dolphin were predicted to have a moderate risk of plastic ingestion. Interestingly, cranes, waterfowl and wading birds were deemed at low or negligible risk from plastic litter. This risk matrix methodology can be applied to other waterways and taxa to assess the risk posed by plastic. It can also be readily updated as more information becomes available. This review enables decision makers to bridge a data gap by providing a tool for conservation and management before comprehensive empirical data is available.
... Debris ingestion has been recorded in 81 of 123 marine mammal species, all seven sea turtle species, and 203 of 406 seabird species to date (Kühn, Bravo Rebolledo, & Van Franeker, 2015), and these numbers are increasing with time (Provencher et al., 2017). Debris is ingested both due to mistaken identity for food (Roman, Schuyler, Hardesty, & Townsend, 2016;Schuyler, Hardesty, Wilcox, & Townsend, 2012), as well as incidental ingestion during feeding (Alexiadou, Foskolos, & Frantzis, 2019). The dangers of debris ingestion to marine megafauna have been known since the 1950s, where deaths among captive marine animals at aquariums and oceanariums often resulted from animals swallowing indigestible foreign material (Walker & Coe, 1989). ...
... The dangers of debris ingestion to marine megafauna have been known since the 1950s, where deaths among captive marine animals at aquariums and oceanariums often resulted from animals swallowing indigestible foreign material (Walker & Coe, 1989). Debris ingestion mortalities have been recorded among cetaceans, pinnipeds, sea turtles, and seabirds (Alexiadou et al., 2019;Wilcox, Puckridge, Schuyler, Townsend, & Hardesty, 2018). Death can be caused by gastric blockage, starvation, perforation, or rupture of the gastrointestinal tract (Pierce, Harris, Larned, & Pokras, 2004;Roman, Bell, Wilcox, Hardesty, & Hindell, 2019), consequent peritonitis and septicaemia (Baulch & Perry, 2014;Panti et al., 2019;Unger et al., 2017), fecal compaction, and wasting (Nelms et al., 2016;Rosolem Lima et al., 2018;Wilcox et al., 2018). ...
... Among cetaceans, though debris ingestion deaths are commonly reported (Baulch & Perry, 2014), few studies reported the specific items ingested. Where items are reported, film-like plastics including plastic bags, plas-tic sheeting, and packaging account for most of the items ingested by cetaceans and causing fatal gastric obstructions, typically in the stomach (Alexiadou et al., 2019) (Table 1). The highest number of ingested debris items reported occurred in sperm whales, Physeter macrocephalus (Alexiadou et al., 2019;Jacobsen, Massey, & Gulland, 2010;Unger et al., 2016), with one individual F I G U R E 1 Study locations of cetaceans, pinnipeds, sea turtles, and seabirds spanned all inhabited continents (COD debris ingestion) containing 135 items, predominantly plastic bags (Alexiadou et al., 2019). ...
Article
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Pollution by plastic and other debris is a problem affecting the world's oceans and is increasing through time. The problem is so large that prioritizing solutions to effect meaningful change may seem overwhelming to the public and policy makers. Marine megafauna are known to mistakenly eat anthropogenic debris and die from consequent gastrointestinal blockages, perforations and malnutrition, as well as suffer sublethal impacts. We collated information on which specific items were ingested and responsible for causing death across 80 marine species, including cetaceans, pinnipeds, sea turtles, and seabirds. We evaluated which items were responsible for the highest mortality, and which, if reduced by policy responses or other means, could result in the largest reduction in debris mortality. A limited number of consumer items were shown to be responsible for most megafauna deaths. Flexible plastic is responsible for the largest proportion of debris deaths, primarily due to gastric obstructions. Disproportionately lethal items included plastic bags/sheets/packaging, rope/fishing nets, fishing tackle and balloons/latex. Smaller items, including "microplastics," though abundant, were seldom implicated in mortality. We provide suggestions to directly curb debris deaths of marine megafauna by prioritizing policies that would reduce or eliminate the input of disproportionately hazardous items into the marine system.
... As with most knowledge gaps regarding cetaceans in the Aegean Sea, conservation issues are not an exception. A few relevant publications exist and have documented potential threats (e.g., [4,6,19,28,30,53,74,[101][102][103][104]). Unfortunately, the concurrent lack of cetacean abundance and fine-scale distribution data hinder the evaluation of the threats' relative severity. ...
... 2. Interaction with marine debris (Fig. 5b, c): The Mediterranean Sea is characterized by one of the highest concentrations of debris in the world [110][111][112]. Ingestion of fishing gear and other marine debris, mainly macroplastics (i.e., >5 mm), can thus be common among most cetacean species of the Aegean Sea with often lethal consequences [74,101]. Two cases of excessive ingestion of macroplastics by sperm whales have been recorded in the Aegean Sea ( [101], PCRI, unpublished data). ...
... Ingestion of fishing gear and other marine debris, mainly macroplastics (i.e., >5 mm), can thus be common among most cetacean species of the Aegean Sea with often lethal consequences [74,101]. Two cases of excessive ingestion of macroplastics by sperm whales have been recorded in the Aegean Sea ( [101], PCRI, unpublished data). In one of these cases, the plastic debris was of both Greek and Turkish origin [101]. ...
Chapter
The underwater habitat complexity of the Aegean Sea renders it home to a diversity of cetacean species. From shallow-diving piscivores to teuthophagous deep divers, this sea hosts seven regular cetacean species (Delphinidae, Phocoenidae, Physeteridae, and Ziphiidae), while five more species have been reported as visitors. Despite this high biodiversity, little is known about this taxon, with most available information referring only to presence data. Due to an ever-increasing human development in the area, seven threats can be identified so far: interactions with fisheries and plastic debris, noise and chemical pollution, shipping, climate change, and epizootics. The concurrent absence of abundance data for these apex predators and the lack of protection areas and law enforcement undermine the survival of the cetaceans in the Aegean Sea. Based on these deficiencies and the scarce governmental funding, we propose that research effort should focus on three main topics: abundance, fine-scale distribution, and ecology. Only with this information available, the monitoring of anthropogenic threats will allow the assessment of the effectiveness of potential conservation measures.
... Litter ingestion by marine mammals in the Mediterranean Sea is less documented in the scientific literature than for other organisms (e.g. fish, marine birds and sea turtles) [68], although several cases have been reported worldwide [70]. So far, the existing information regarding interactions between large marine mammals and marine litter is related more to entanglement rather than ingestion [70]. ...
... Marine litter was found in the stomach of 10 out of 13 sperm whales (77%) stranded along the Italian coast (Western Mediterranean Sea subregion) between the period from 2009 to 2013, and it was composed mostly of plastic [71]. Similarly, marine litter found in the stomachs of six out of ten sperm whales stranded along the Ionian and Aegean Seas from 1993 to 2014; the majority of litter was plastics except only one metal wire tied at the top of a plastic bag [68]. According to the authors, the high percentage of plastic sheets in the stomachs of sperm whales is probably linked with the high abundance of plastic bags and packaging in both the water column and the seafloor. ...
... According to the authors, the cause of death was probably the direct result of ingesting plastic bags [79]. Plastics were found in the stomach of one Cuvier's beaked whale stranded along the Greek Ionian Sea coasts (the Ionian Sea and the Central Mediterranean Sea subregion), and its death may be caused by gastric blockage [68]. ...
Chapter
Marine litter is an environmental problem of global concern with well-documented impacts on marine biodiversity and ecosystems. At a global scale, marine litter is mainly composed of plastic. Plastics can affect marine organisms mainly through ingestion and entanglement but also through the facilitation of transport of organisms via rafting or the provision of new habitats for colonization. Impacts vary according to the type and size of the plastics and can occur at different levels of biological organization in a wide variety of habitats. In this chapter, we reviewed and synthesized literature in order to describe the impact of litter on marine life in the Mediterranean sensitive ecosystem. The review focused on the following impact categories: ingestion, entanglement and other effects (e.g. colonization and rafting). In the Mediterranean, reports of ingestion were made for more than 49,454 individuals from 116 species, of which the taxonomic group with the greatest number of species impacted was Teleosts (~59%). Forty-four species were found entangled in marine litter (59% were invertebrates, mainly Cnidarians), of which the species with the highest number of entanglement records in the Mediterranean Sea was the loggerhead sea turtle (Caretta caretta). One hundred and seventy-eight taxa were found rafting on floating objects or using marine litter as a substratum, including Chromista and Bacteria. The most common phyla rafting on marine litter were Arthropods and Cnidarians.
... Understanding cause of death requires a postmortem examination conducted in a very rigorous manner by an expertise person; in fact, classifying deaths with respect to ingested items is often a true challenge (Roman et al., 2020). Anyway, megafauna can ingest debris due to mistaken identity for food (Roman et al., 2016(Roman et al., , 2020Schuyler et al., 2012), as well as incidental ingestion during feeding (Alexiadou et al., 2019). Indigestible plastic debris may affect individual fitness, with negative consequences on survival . ...
... Mortalities due to ingestion were reported in cetaceans, pinnipeds, sea turtles, and marine birds (Lazar and Gračan, 2011;Wilcox et al., 2018;Alexiadou et al., 2019;Roman et al., 2020). However, cases of plastic ingestion and their impact on direct mortality or injuries have been rather rarely documented in sharks and rays. ...
Chapter
Due to the recognized negative impact for marine biodiversity, plastic pollution in seas and oceans is nowadays a global problem. Sharks and rays are apex predators, which are also vulnerable to plastic pollution due to threats related with entanglement, ingestion, and habitat degradation, but, paradoxically, the science community deserved them less attention. Entanglement with ghost nets and other plastic materials such as ropes, straps, bags is common, and many evidences of plastic ingestion in shark are also reported. Large sized planktivorous sharks and mobulid rays are seriously exposed to microplastic pollution due to their feeding mode. Despite the occurrence of plastic pollution, elasmobranchs seem to be much more threatened by the effects of the overexploitation through targeted fisheries and by-catch than other stressors. Best practices and environmental laws together with a wide popular participation are necessary to overcome these problems.
... Plastic pollution in the marine environment is a global threat (Borrelle et al., 2020), considered as one of the major environmental issues of our times, comparable with climate change and overfishing (Avery-Gomm et al., 2019;Stafford and Jones, 2019). Macroplastics (>5 mm) are known to affect the marine ecosystem, as marine organisms ingest or become entangled in plastic litter (Sheavly and Register, 2007), which has an impact on their health, sometimes even with fatal consequences (Franco-Trecu et al., 2017;Reinert et al., 2017;Alexiadou et al., 2019). Effects of microplastics (<5 mm) on marine biota are less known (Bucci et al., 2020), as this subject has only recently drawn the attention of marine research activities (Modica et al., 2020). ...
... Moreover, due to its importance for various cetacean species, ACCOBAMS considers this area as a CCH. Thus, high concentrations of macroplastics in the Sallum Gulf should raise the alarm, as it is known that cetacean species are particularly vulnerable to macroplastics, often with lethal consequences (Alexiadou et al., 2019). Notably, we found that the vast majority (99%) of this predicted concentration in Sallum Gulf, originates from sources beyond the Egyptian borders (Figure 11, see also Supplementary Material). ...
Article
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Micro- and macro-plastics pollution is a growing threat for marine biodiversity, ecosystem functioning, and consequently human wellbeing. Numerical models that consider main sources of plastics and simulate their dispersal characteristics are unique tools for exploring plastic pollution in marine protected areas (MPAs). Here, we used a Lagrangian plastic drift model, taking into account various sizes/types of plastic litter, originating from major land-based sources (coastal cities and rivers), to predict plastic accumulation zones in protected areas of the Mediterranean Sea (i.e., nationally designated MPAs, Natura 2000 sites, and Cetacean Critical Habitats). The model predicted that the size of plastic litters plays a key role in their dispersion and ultimate destination (i.e., larger litter travel longer distances). Most of the studied Mediterranean countries (13 out of 15) had at least one national MPA with over 55% of macroplastics originating from sources beyond their borders. Consequently, in many cases, local efforts to reduce plastic pollution in protected areas would be insufficient, especially for macroplastics management. Transboundary collaboration among Mediterranean countries is critical for implementing successful management plans against plastic pollution in their territorial waters and specifically in MPAs.
... Plastic pollution, a large component of litter found in the marine environment (ca. 70% by frequency; Nelms et al., 2017), is of particular concern, due to the increasing evidence of its potential to cause ecological and socio-economic impacts, such as entanglement (Duncan et al., 2017), ingestion and the associated increased risk of exposure to chemical contaminants (Alexiadou et al., 2019;Tanaka et al., 2013), smothering and abrasion, spread of invasive species (Gregory, 2009), and detrimental effects on human health and well-being (Beaumont et al., 2019). Despite their statutory designated status and legal protection from discrete threats, MPAs may be exposed to the potential impacts of plastic pollution, due to its diffuse nature and lack of constraint by legislative and/or political boundaries. ...
... The lack of difference in litter density on beaches inside and outside MPAs suggests that sensitive sites may be exposed to the potential impacts of plastic pollution (e.g. entanglement, ingestion, smothering and abrasion, spread of invasive species, and detrimental effects on human health and well-being; Alexiadou et al., 2019;Beaumont et al., 2019;Duncan et al., 2017;Lamb et al., 2018). By its diffuse nature, litter in the marine environment is not constrained by legislative and/or political boundaries so action beyond MPA site management is needed to address this issue, at local, national and international levels. ...
Article
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Marine Protected Areas (MPAs) are designated to enable the management of damaging activities within a discrete spatial area, and can be effective at reducing the associated impacts, including habitat loss and over-exploitation. Such sites, however, may be exposed to the potential impacts from broader scale pressures, such as anthropogenic litter, due to its diffuse nature and lack of constraint by legislative and/or political boundaries. Plastic, a large component of litter, is of particular concern, due to increasing evidence of its potential to cause ecological and socio-economic damage. The presence of sensitive marine features may mean that some MPAs are at greater potential risk from the impacts of plastic pollution than some non-protected sites. Understanding the abundance, distribution and composition of litter along coastlines is important for designing and implementing effective management strategies. Gathering such data, however, can be expensive and time-consuming but litter survey programmes that enlist citizen scientists are often able to resolve many of the logistical or financial constraints. Here, we examine data collected over 25-years (1994–2018), by Marine Conservation Society volunteers, for spatial patterns in relation to the English MPA network, with the aim of highlighting key sources of litter and identifying management priority areas. We found that MPAs in southeast (Kent) and southwest (Cornwall and Devon) England have the highest densities of shore-based litter. Plastic is the main material constituent and public littering the most common identifiable source. Items attributed to fishing activities were most prevalent in southwest MPAs and sewage related debris was highest in MPAs near large rivers and estuaries, indicating localised accumulation. When comparing inside and outside of MPAs, we found no difference in litter density, demonstrating the need for wider policy intervention at local, national and international scales to reduce the amount of plastic pollution.
... Tens of nematodes were recovered from two stomachs (Pm4 & 7) and have already been identified as the species Anisakis physeteris (Baylis, 1923) (Mattiucci et al., 2014). Megaplastic and macroplastic material was also found in five stomach contents (Pm4, 5, 6, 8 & 10, Fig. 2, Alexiadou et al., 2019), with the stomach of the individual stranded in Mykonos (Pm4) containing nearly 100 pieces . ...
... Commercial fish and cephalopod species were not found in the sperm whale stomachs suggesting that direct competition with fisheries may not currently affect the conservation of sperm whales in this region. Despite this, there are many other anthropogenic activities that undermine their survival and make their future uncertain in the eastern Mediterranean Sea (e.g., ship-strikes, oil and gas exploration, and plastic debris pollution, Alexiadou et al., 2019;Frantzis et al., 2019;Madsen et al., 2006). ...
Article
Sperm whales (Physeter macrocephalus) inhabiting the world’s oceans, prey mainly on cephalopods, but also feed on fish when found in higher latitudes. However, the feeding habits of endangered Mediterranean sperm whales have received little attention with thus far only two individuals analysed for their stomach contents. This study expands the available knowledge using analysis of the stomach contents from nine individuals stranded in Greece between 2005 and 2014. 48,166 prey remains were examined in total and 28,258 of them were identified to show that sperm whales fed on 18 prey species (17 cephalopods and one teleost) from 14 different families. 15 of these species were deep-sea squids, which are not presently targeted by fisheries. The most important prey species, both in terms of numerical abundance (%N) and abundance by weight (%W), was the oceanic squid Histioteuthis bonnellii (%N=48.4, %W=66.3) followed by H. reversa (%N=28.4, %W=13.8) and Octopoteuthis sicula (%N=8.5, %W=17.2). Calf sperm whales consumed smaller cephalopods of these three prey species than non-calves, probably because larger cephalopods are more difficult to catch. The vast majority of ingested cephalopods were gelatinous, slow-swimming and small. Therefore, sperm whales inhabiting the Greek Seas and likely the whole eastern Mediterranean Sea, appear to target prey that are easy to catch, but need to be consumed in great numbers to fulfil the energy requirements of the whales.
... Similarly, among eight cetacean individuals stranded in La Réunion and necropsied by the organization GLOBICE, none had ingested macrolitter (GLOBICE, unpubl. data), even though in other regions whales and dolphins have been found with ingested plastics (Unger et al. 2016, Alexiadou et al. 2019. Regardless of the scarcity of studies, however, it is inevitable that many individuals have likely ingested microplastics, especially for filter-feeding species. ...
... The relationships between marine mammals and plastic pollution is not well studied in the Eastern Mediterranean until now, although macroplastic debris (> 5 mm) were found in the stomachs of different cetaceans from four species (harbour porpoise, Risso's dolphin, Cuvier's beaked whale and sperm whale) with the highest frequency of occurrence in sperm whales (60%) stranded in Greece [83]. ...
Chapter
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... One observation of a bird of prey providing discarded plastic to dependent nestlings was reported by a study monitoring 12 Eleonora's falcon nests by camera on the small islet of Anidro, Eastern Aegean Sea, Greece, that recorded a parental female successively feeding the nestlings with a snack wrapper [73]. As regards information on cetaceans, Alexiadou et al. [74] analysing the stomach content of 34 individuals from seven odontocete species stranded in Greece found macro-plastic ingestion in the stomachs of one harbour porpoise Phocoena phocoena and five sperm whales Physeter macrocephalus stranded on the Aegean coasts. The authors reported gastric blockage from plastic that was presumably lethal in three out of all the animals examined, including one case of a sperm whale in the Aegean Sea. ...
Chapter
The present review provides a thorough analysis of the published scientific results on the distribution, sources and impacts of macro-litter/macro-plastics (>2.5 cm), meso (0.5 cm < < 2.5 cm) and microplastics (MPs) (<0.5 cm) in the Aegean Archipelago. About 50 published works have been analysed half of them focusing on the impacts in biota, yet the information retrieved is still insufficient. Few studies have followed common methodologies. The geographical coverage is limited, especially for beach litter, riverine litter and floating litter. From the available data it is shown that litter on the Aegean beaches exceed by far the threshold value for achieving the Good Environmental Status (GES) sensu the MSFD or the UNEP/IMAP. Records on organisms’ entanglement in marine litter and on ingestion of plastics and microplastics show that several studied species (7 for entanglement and 18 for ingestion) from echinoderms and mussels to marine mammals have been affected. Despite that the area is subjected to several pressures leading to plastics pollution. Policy measures in Greece and Turkey, the two bordering countries, have only very recently come into force. More efforts are needed by both the scientific community and the policy makers in order to understand, quantify and mitigate the problem of marine litter and microplastics in the Aegean Archipelago.
... Use of stranding records is a valid and sustainable approach to study the diversity of local marine mammal species [41][42][43][44][45] , and to investigate the parasite fauna hosted by these animals. Stranding events can occur for several reasons, including natural causes such as illness, environmental factors, and anthropogenic causes including bycatch, vessel strikes, plastic ingestion, or acoustic trauma [46][47][48][49][50][51][52][53][54] . Despite these advantages, parasitological studies on stranded cetaceans are affected by the decomposition state of the animals. ...
Article
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Parasite biodiversity in cetaceans represents a neglected component of the marine ecosystem. This study aimed to investigate the distribution and genetic diversity of anisakid nematodes of the genus Anisakis sampled in cetaceans from the Northeast Atlantic Ocean and the Mediterranean Sea. A total of 478 adults and pre-adults of Anisakis spp. was identified by a multilocus genetic approach (mtDNA cox 2 , EF1 α − 1 nDNA and nas 10 nDNA gene loci) from 11 cetacean species. A clear pattern of host preference was observed for Anisakis spp. at cetacean family level: A. simplex (s.s.) and A. pegreffii infected mainly delphinids; A. physeteris and A. brevispiculata were present only in physeterids, and A. ziphidarum occurred in ziphiids. The role of cetacean host populations from different waters in shaping the population genetic structure of A. simplex (s.s.), A. pegreffii and A. physeteris was investigated for the first time. Significant genetic sub-structuring was found in A. simplex (s.s.) populations of the Norwegian Sea and the North Sea compared to those of the Iberian Atlantic, as well as in A. pegreffii populations of the Adriatic and the Tyrrhenian Seas compared to those of the Iberian Atlantic waters. Substantial genetic homogeneity was detected in the Mediterranean Sea population of A. physeteris. This study highlights a strong preference by some Anisakis spp. for certain cetacean species or families. Information about anisakid biodiversity in their cetacean definitive hosts, which are apex predators of marine ecosystems, acquires particular importance for conservation measures in the context of global climate change phenomena.
... Risso's dolphins are found entangled in fishing gears more often than other cetaceans 50 . Pollution is also a concern for their conservation, as they are negatively affected by plastic debris and noise [51][52][53] . ...
Article
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Deep-habitat cetaceans are generally difficult to study, leading to a limited knowledge of their population. This paper assesses the differential distribution patterns of three deep-habitat cetaceans (Sperm whale— Physeter macrocephalus, Risso’s dolphin— Grampus griseus & Cuvier’s beaked whale— Ziphius cavirostris ). We used data of 842 opportunistic sightings of cetaceans in the western Mediterranean sea. We inferred environmental and spatio-temporal factors that affect their distribution. Binary logistic regression models were generated to compare the presence of deep-habitat cetaceans with the presence of other cetacean species in the dataset. Then, the favourability function was applied, allowing for comparison between all the models. Sperm whale and Risso’s dolphin presence was differentially favoured by the distance to towns in the eastern part of the western Mediterranean sea. The differential distribution of sperm whale was also influenced by the stability of SST, and that of the Risso’s dolphin by lower mean salinity and higher mean Chlorophyll A concentration. When modelling the three deep-habitat cetaceans (including Cuvier’s beaked whale), the variable distance to towns had a negative influence on the presence of any of them more than it did to other cetaceans, being more favourable far from towns, so this issue should be further investigated.
... The presence of macroplastics has also been reported in the stomachs of four marine mammals (the harbour porpoise Phocoena phocoena, the Risso's dolphin Grampsus griseus, the Cuvier's beaked whale Ziphius cavirostris and the sperm whale Physeter macrocephalus) as they stranded along the Greek coasts from 1993 to 2014. This supports the idea that plastics are ingested by the half of the cetacean species that regularly occur in the Greek Seas [35]. ...
... The relationships between marine mammals and plastic pollution is not well studied in the Eastern Mediterranean until now, although macroplastic debris (> 5 mm) were found in the stomachs of different cetaceans from four species (harbour porpoise, Risso's dolphin, Cuvier's beaked whale and sperm whale) with the highest frequency of occurrence in sperm whales (60%) stranded in Greece [83]. ...
... choking; toxicological effects may arise due to ingestion of toxic residues leached from polymers (Alexiadou et al., 2019;Tanaka et al., 2013) and ...
Article
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This research is the first to assess marine litter and plastic pollution in India's first marine protected area (MPA), the Gulf of Kachchh Marine Protected Area (GOKMPA). We compare it to two non‐protected areas, that is, Okha Beach and Beyt Dwarka, known for their high industrial and tourist activity, respectively. Standing‐stock surveys were used to collect primary litter data, while questionnaire surveys were used to learn about people's perception and attitude towards the plastic pollution problem in the study area. We found that plastic was the most common component of the litter at all the sites and that it was primarily of terrestrial origin. Compared to non‐protected sites, GOKMPA had the lowest litter density but the highest proportion of plastic litter. Single‐use plastic bottles were the most counted items at all the sites, regardless of the conservation status of the sites. The majority of people (locals, visitors, and fishers) around these sites expressed concern about waste but were hesitant to take responsibility and discourage or prevent littering. We noted that designating coastal territories as protected areas helps in reducing plastic pollution while also conserving habitat and biodiversity. However, this could change rapidly due to either mishandling of litter within MPAs or neighboring non‐PAs, and also because plastics pose an actual toxicity risk when present even at minimal concentrations in the environment. We recommend combining preventive, mitigating, and curative measures in areas where risk hotspots for plastic litter are identified, and such sites must be constantly monitored. Long‐term solutions could include transitioning from a linear to a circular economy, which would involve goals for reducing plastic waste and instituting more sustainable production and consumption patterns.
... Occurrence of plastics in the stomachs of sperm whales has been reported widely (e.g. De Stephanis et al. 2013;Alexiadou et al. 2019). Macroplastics were found in the stomach content with the highest frequency in the sperm whales (60%) of Greek waters . ...
... Microplastics imitate the presence of food, potentially blocking and jeopardizing the digestive systems of aquatic organisms (Lehtiniemi et al., 2018;Welden et al., 2018). Various marine invertebrates (Rotjan et al., 2019;Wright et al., 2013), fish Jovanović, 2017;Lusher et al., 2013;Tanaka and Takada, 2016), marine reptiles (Caron et al., 2018;Wabnitz and Nichols, 2010), and sea mammals (Alexiadou et al., 2019;Kühn and van Franeker, 2020) have been observed ingesting plastics of different sizes. Furthermore, there is increasing evidence that microplastics can be translocated into an organism's tissue from the digestive tract (Schür et al., 2019) and transferred through the food chain (Akhbarizadeh et al., 2019;Carbery et al., 2018;Farrell and Nelson, 2013;Wright et al., 2013), raising concerns regarding the negative consequences of bioaccumulation from one trophic level to the next (Sfriso et al., 2020). ...
Article
This study investigated the abundances and characteristics of microplastics in sediments and sandfish (Holothuria scabra) in Lampung and Sumbawa, Indonesia. Microplastics were found in 89.02% of all sandfish samples, with an average abundance of 2.01 ± 1.59 particles individual-1. The abundance of microplastics was 58.42 ± 24.33 particles kg-1 in surface sediments. Furthermore, there was a positive relationship between the abundance of microplastics in sandfish and sediments. Fragments and fibers with small-sized microplastics (300-1000 μm) were the most abundant types found in sandfish and sediments. Fourier-transform infrared (FTIR) analysis showed that polyethylene (30.08%), polypropylene (30.08%), polyurethane (12.20%), and polyethylene terephthalate (8.94%) were the most abundant polymers in the samples. Our results strongly indicate that microplastics in Lampung and Sumbawa originate from the fragmentation of large plastics. Better solid waste management in Indonesia is needed to reduce plastic waste leakage, which could become microplastics.
... Marine plastics could cause great harms to marine organisms, one of which is ingestion by marine organisms (Puskic et al., 2020;Markic et al., 2020). It is shown that plastics accounted for 98.7% of ingested marine debris in sperm whale (Physeter microcephalus), among which plastic bags represent 48.7% (Alexiadou et al., 2019). ...
Article
In recent years, the ecological risks of plastics to marine environments and organisms have attracted increasing attention, especially the leachates from plastics. However, a comprehensive knowledge about the leaching characteristics and subsequent toxicological effects of leachates is still sparse. In this study, 15 different plastic products were immersed in simulated seawater and fish digest for 16 h. The leachates were analyzed through non-target and target analyses and their toxicological signatures were assessed by bioassays. In total, 240 additives were identified from the plastic leachates, among which plasticizers represented the most (16.7%), followed by antioxidants (8.7%) and flame retardants (7.1%). Approximately 40% of plastic leachates exhibited significant inhibitory effects on the bioluminescence using a recombinant luminescent assay. In addition, both the hyperactive and hypoactive behaviors were displayed in the larvae of marine medaka (Oryzias melastigma) exposed to some plastic leachates. In general, the number and amount of identified compounds under simulated fish digest were less than those under simulated seawater. However, the simulated fish digest leachates triggered higher toxicity. Redundancy analysis demonstrated that identified additives did not adequately explain the toxicological effects. Future research should focus on the identification of more additives in the plastic leachates and their potential ecological risks.
... Similar studies estimated 269,000 tons of plastic in the ocean (Keswani et al., 2016) and suggest 80% of marine plastics originate from land-based sources (Li et al., 2016). The dangers of entanglement and plastic ingestion by marine organisms are well documented (Gall and Thompson, 2015;Rochman et al., 2016;Galloway et al., 2017;Alexiadou et al., 2019;Consoli et al., 2019;Parton et al., 2019), however the colonization of plastics by potentially harmful microbes is not fully understood. Upon entering the marine environment plastics are rapidly colonized by biofilms populated by a diverse community of microbial life (Zetter et al., 2013;McCormick et al., 2014;Keswani et al., 2016;Rummel et al., 2017;Miao et al., 2019;Amaral-Zettler et al., 2021). ...
Article
Polyethylene terephthalate (PET) is frequently used in the food and beverage industry and therefore contributes greatly to plastic marine debris. The fecal pollution indicator bacteria Enterococcus is used for marine water contamination assessments and is regularly found in storm water discharge. In order to examine if PET drinking bottles act as refuges for Enterococcus, a study was conducted within euhaline tidal waters of Wrightsville Beach, NC, USA via the deployment of bottle floats positioned nearby two stormwater outfall pipes. Bottles were retrieved weekly to assess the accumulation of fecal bacteria and phytoplankton. Each bottle was analyzed for the presence of Enterococcus on plastic surfaces and within water inside the bottle. Abundance of Enterococcus and planktonic chlorophyll α was found to be significantly greater in association with PET bottles versus the surrounding waters. Bottles were observed to act as reservoirs for both Enterococcus and phytoplankton with concentrations well above the state, federal, and WHO standards.
... From time to time the procedure has been refined recording the number, color, size, and shape of the micro and nano plastics found. Through these studies, sieves for micro plastics up to 200 mm have been introduced [121,122]. Direct observation for morphology diagnosis are performed by stereomicroscopy that is applied in both animal tissue as mussels [123] and vegetable, one as surface of seeds and germinated roots [112]. Alternatively, the samples of tissue are processed in laboratory through acid attack and/or enzymatic digestion [47,124]. ...
Article
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Nanoplastics (NPs) are considered emerging pollutants, namely unregulated contaminants whose toxic effect on humans and the environment has been demonstrated or suspected. They are the result of the physical fragmentation of the plastics that over time reach smaller dimensions (<100 nm). The issues related to the characterization and quantification of NPs in the environmental matrices are mainly related to the infinitesimal size, to the fact that they are found in bulk, and to the different physico-chemical forms in which the same polymer can evolve over time by degradation. To deal with the study of a new class of pollutants it is necessary to assess the entire analytical method, carefully considering every single step (sampling, cleanup, qualitative, and quantitative analysis) starting from the validation method in the laboratory. This paper reviews the analytical method steps, focusing on the first ones, which the current literature often underestimates: laboratory tests, sampling, and sample processing; in fact, most errors and the quality of the analyses often depend on them. In addition, all newly introduced sample processing methods were examined.
... In particular, the most recorded plastic objects were shopping bags, plastic sheets, bottles, buoys and polystyrene boxes, and the majority of these items was smaller or equal to 50 cm. Even if few studies mentioned the specific object ingested, these kind of items (especially plastic bags and sheets) are the ones that could cause cetacean fatal gastric obstructions (Alexiadou et al., 2019;Roman et al., 2021). ...
Article
The Sardinian and Sicilian Channels are considered hotspots of biodiversity and key ecological passages between Mediterranean sub-basins, but with significant knowledge gaps about marine mammal presence and potential threats they face. Using data collected between 2013 and 2019 along fixed transects, inter and intra-annual cetacean index of abundance was assessed. Habitat suitability, seasonal hot spots, and risk exposure for plastic were performed using the Kernel analysis and the Biomod2 R-package. 661 sightings of 8 cetacean species were recorded, with bottlenose and striped dolphins as the most sighted species. The north-eastern pelagic sector, the coastal waters and areas near ridges resulted the most suitable habitats for these species. The risk analysis identified the Tunis, Palermo, and Castellammare gulfs and the Egadi Island as areas of particular risk of plastic exposure. The study represents a great improvement for cetacean knowledge in this region and contributes to the development of effective conservation strategies.
... various other anthropogenic stresses such as plastic [5,24,74] , chemical [45 , 62] and noise pollution [47,71,108] , must also tolerate both small and large-scale climatic changes [83] . Due to these stressors, multiple cetacean populations may eventually collapse, which could result in permanent, long term consequences for marine ecosystem functioning and services [4] . ...
Article
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Climatic changes have had significant impacts on marine ecosystems, including apex predators such as cetaceans. A more complete understanding of the potential impacts of climate change on cetaceans is necessary to ensure their conservation. Here we present a review of the literature on the impacts of climate change on cetacean distribution, habitat and migrations and highlight research gaps. Our results indicate that due to rising sea surface temperatures (SSTs) and/or reducing sea ice extent, a variety of impacts on the distribution, habitat and migration of cetaceans have been observed to date and several more are predicted to occur over the next century. Many species have demonstrated a poleward shift, following their preferred SSTs to higher latitudes, and some have altered the timing of their migrations, while others appear not to be affected. These changes may benefit certain species, while others will be placed under extreme pressure and may face increased risk of extinction. Broader implications may include increased inter-specific competition, genetic alterations, ecosystem-level changes and conservation challenges. Existing research on the topic is both extremely limited and unevenly distributed (geographically and phylogenetically). Further research is necessary to determine which species and populations are most vulnerable and require the earliest conservation action.
... In the Mediterranean Sea, the plastic ingestion by different marine mammals is less evaluated in comparison to other marine organisms such as mussels, fish, sea turtles, and marine birds (Alexiadou et al., 2019) although several cases have been reported worldwide (De Stephanis et al., 2013). Much of the interactions between bulky marine mammals and plastic litter are more related to entanglement than ingestion (De Stephanis et al., 2013). ...
Article
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Microplastic pollution is one of the emerging threats across the globe and is becoming a topic of intense study for environmental researchers. At present, almost all of the world’s oceans and seas are contaminated with microplastics but the Mediterranean Sea has been recognized as a target hotspot of the world as the microplastic concentration in this region is approximately four times greater than the North Pacific Ocean. Because of the distinguishing semi-enclosed morphology of the Mediterranean Sea, and different plastic waste generating activities originating from surrounding countries the Mediterranean Sea is highly vulnerable to microplastic pollution. Different plastic families have been reported in the Mediterranean Sea and the Physico-chemical features of these plastic polymers play an important role in the interactions between these plastic particles and other organic matter in the water bodies. The ingestion of microplastics by marine animals is an issue of concern as microplastic acts as vectors for other harmful pollutants adsorbed onto their surface. This review provides a detailed discussion on the persistence of microplastics in the Mediterranean Sea that have been identified in surface water and also in sediments and deep sea-floor. Various sources of these synthetic materials and the intensity of low and high-density polymers pollution in the Mediterranean Sea have also been discussed. This review also focuses on the threatened species in the Mediterranean Sea and the fate of the plastisphere community in its ecosystem. In the end, we highlight a series of important regulations and policies adopted by Mediterranean countries to control and manage the microplastic pollution in this region.
... For bigger animals, such as sea turtles, sharks and marine mammals, plastic ingestion reported in field samples often refers to meso-and macroplastic items above 5 mm (Alexiadou et al., 2019;Bernardini et al., 2018;Smith, 2018). To our knowledge, exposure studies with microplastic fibers were not conducted with higher taxa than fish so far. ...
Article
Awareness of microplastic pollution in aquatic environments increased strongly during the last decade. Environmental monitoring studies detected microplastic items in every tested water body and found them in various aquatic organisms. Yet, many studies conducted so far, refer to microplastic particles and spheres but not fibers. Microplastic fibers are often not considered due to methodological issues and high contamination risk during sampling and analysis. Only a few of the microplastic exposure studies with aquatic organisms were conducted with microplastic fibers. Recent effect studies demonstrated several negative impacts of microplastic fibers on aquatic organisms, which include tissue damage, reduced growth, and body condition and even mortality. Such negative effects were predominantly observed in taxa at the basis of the food chain. Higher taxa were less heavily affected in direct exposure experiments, but they presumably suffer from negative effects on organisms at lower food chain levels in the wild. Consequently, ongoing and future pollution with microplastic fibers may disturb the functioning of aquatic ecosystems. The present review outlines the current state of knowledge on microplastic fiber abundance in nature, bioavailability, and impacts on aquatic animals. Based on these findings, we recommend inclusion of microplastic fibers in prospective monitoring studies, discuss appropriate methods, and propose to conduct exposure studies with – as well as risk assessments of – these underestimated pollutants.
... For pinnipeds, the pathway of ingestion is presumed to be from consumption of prey species that have consumed microplastics (Eriksson and Burton 2003), although many researchers have anecdotal accounts of marine mammals (and other taxa) playing with and directly consuming plastics of various sizes. The same is true for cetaceans (e.g., (Baird and Hooker 2000), with populations of both large and small cetaceans suffering fitness consequences from direct and indirect plastic consumption (Alexiadou et al. 2019;Besseling et al. 2015;De Stephanis et al. 2013;Fossi et al. 2018). ...
Technical Report
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Vessels involved in commercial marine shipping in Canada engage in the movement of goods or people by sea on the Arctic, Atlantic, and Pacific oceans. To explore the ways that the activities associated with commercial shipping can impact the marine environment, a suite of activity-based Pathways of Effects (PoE) conceptual models were developed. PoE conceptual models describe the pathways (linkages) between human activities, associated stressors, and their effects on endpoints, based on current knowledge. A visual representation of each PoE model is supported by text describing each pathway linkage based on scientific literature or expert opinion. Indigenous and local knowledge were not used in the current work. PoE models are useful tools for the scoping phase of a variety of environmental assessment, such as ecological risk assessment, environmental impact assessment, and cumulative effect assessments as they clearly outline activities and stressors and clarify connections between human activities and potential effects on ecological endpoints, and provide a science-based foundation for decision-making. The objective of these models and their supporting evidence is to provide a systematic review of the effects of shipping-associated activities on marine ecosystems. PoE models have been developed for five activities associated with commercial marine shipping in Canada: 1) anchoring and mooring, 2) vessel at rest, 3) grounding and sinking, 4) movement underway, and 5) discharge (divided into two PoE models: ‘debris’ and ‘other’). The PoEs were developed to be broad enough to be adapted for application in a range of environments and locations and detail the potential stressors and effects that could be considered in an assessment. The activity-based PoE models contain fourteen stressors (e.g., substrate disturbance, vessel strikes) and are related to three effects (change in fitness, mortality, and change in habitat) on ten generic endpoints (e.g., marine mammals, physical habitat). The models only include activities related to the commercial movement of goods and people by vessels, not included in this document are other vessel activities such as fishing, seismic surveying, dredging, port operations (e.g., when at-berth and while berthing). Non-commercial vessels (e.g., recreational vessels) are also not specifically included in these models. Though endpoints have been identified for illustrative purposes here, ultimately the assessor is responsible for comprehensively scoping the specific endpoints (e.g., valued components) and stressors to be considered in any assessment. PoE models do not include any evaluation of the relative or absolute impact from these activities on specific endpoints; this would occur in a subsequent assessment step, such as risk assessment.
... Mediterranean sperm whales appear to be especially badly affected (e.g., Roberts, 2003;Mazzariol et al., 2011;IUCN., 2012;de Stephanis et al., 2013;Alexiadou et al., 2019) in comparison to other oceanic areas (e.g., Martin and Clarke, 1986;Evans and Hindell, 2004;Jacobsen et al., 2010;Unger et al., 2016), as shown in Figure 2, and this is likely to be because of the relatively high level of marine litter contamination in this sea area. A quantitative assessment of debris on the Mediterranean seabed found fishing gear was the dominant type of debris present (89%) (Angiolillo et al., 2015) and this may therefore be a particular problem in this region for this species, although more research is needed. ...
Article
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Marine litter is a growing concern for marine animals, including cetaceans for which there is a developing body of evidence showing impacts of both entanglement and ingestion. Better understanding is needed of the current and predicted scales of impacts on cetacean species of both macro- and micro-litter. Some emerging methodological approaches, such as the “threefold approach,” will help address data gaps. The relationship between this form of pollution and some cetaceans is strong and the particular feeding habits, and widespread distribution of two whale species means that they can be proposed as ocean health indicators for macro- and micro-litter impacts at global scales, helping steer research. The species concerned are sperm whales (Physeter macrocephalus), for macro-litter at depth, and fin whales (Balaenoptera physalus), for micro-debris. Once appropriate techniques have been fully developed for non-lethal assessment, other whale species might also be used as indicators of litter pollution in their specific feeding zones.
... These include harmful effects from entanglement and ingestion. The consequences of ingesting large plastic items may be starvation and death, while microplastics may enter food webs from soil and aquatic environments, posing a potential risk to higher animals and humans (Alexiadou et al., 2019;Axworthy & Padilla-Gamino, 2019;Lusher et al., 2015;SAPEA, 2019;Yong et al., 2020). Studies show that zooplankton is adversely affected by microplastics, interfering with not only predatorprey interactions and feeding, but also by adhering to the external carapace (Cole et al., 2013;Van Colen et al., 2020). ...
... Plastic pollution is known to affect marine mammals, through entanglement (Kraus, 2018), ingestion (Alexiadou et al., 2019;De Stephanis et al., 2013;Unger et al., 2016) and potential habitat degradation (Gall and Thompson, 2015;Pawar et al., 2016). One area of specific concern is the exposure of marine mammals to microplastics. ...
Article
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Microplastics receive significant societal and scientific attention due to increasing concerns about their impact on the environment and human health. Marine mammals are considered indicators for marine ecosystem health and many species are of conservation concern due to a multitude of anthropogenic stressors. Marine mammals may be vulnerable to microplastic exposure from the environment, via direct ingestion from sea water, and indirect uptake from their prey. Here we present the first systematic review of literature on microplastics and marine mammals, composing of 30 studies in total. The majority of studies examined the gastrointestinal tracts of beached, bycaught or hunted cetaceans and pinnipeds, and found that microplastics were present in all but one study, and the abundance varied between 0 and 88 particles per animal. Additionally, microplastics in pinniped scats (faeces) were detected in eight out of ten studies, with incidences ranging from 0% of animals to 100%. Our review highlights considerable methodological and reporting deficiencies and differences among papers, making comparisons and extrapolation across studies difficult. We suggest best practices to avoid these issues in future studies. In addition to empirical studies that quantified microplastics in animals and scat, ten studies out of 30 (all focussing on cetaceans) tried to estimate the risk of exposure using two main approaches; i) overlaying microplastic in the environment (water or prey) with cetacean habitat or ii) proposing biological or chemical biomarkers of exposure. We discuss advice and best practices on research into the exposure and impact of microplastics in marine mammals. This work on marine ecosystem health indicator species will provide valuable and comparable information in the future.
... From sperm whales Physeter macrocephalus to harbour porpoises Phocoena phocoena, all odontocetes seem to be at risk of ingesting marine litter. Debris in the forestomach can cause distention, obstruction, ulceration, perforation and peritonitis, or it can functionally alter digestion, induce satiation and cause starvation and general debilitation (Jacobsen et al. 2010, Unger et al. 2016, Puig-Lozano et al. 2018, Terio et al. 2018, Alexiadou et al. 2019. Rope and fishing line and nets may wrap around the larynx while being ingested or while being regurgitated (Wells et al. 2008, Levy et al. 2009). ...
Article
Ingestion of abnormal materials by cetaceans has been reported worldwide, but few studies have investigated the causes of foreign material ingestion. We retrospectively analysed necropsies performed between 2012 and 2019 on 88 cetaceans stranded along the coast of Catalonia, Spain, and evaluated the association of abnormal ingested materials with 2 risk factors, namely disease of the central nervous system (CNS) and maternal separation. Abnormal materials were found in the digestive tract in 19 of 88 (21.6%) cetaceans; of these, 13 (60%) had lesions in the CNS, such as morbilliviral encephalitis, neurobrucellosis or encephalomalacia, and 3 were diagnosed as having experienced maternal separation. In a logistic regression model, CNS lesions and maternal separation were identified as risk factors for ingestion of foreign material, but with wide confidence intervals, probably due to the small sample size. In contrast, abnormal ingestion was not identified in any of the 25 (28%) cetaceans whose cause of death was attributed to interaction with humans. Abnormal ingestion should be interpreted with caution, and efforts should be made at necropsy to exclude CNS diseases through pathologic and microbiologic investigations. If disease of the CNS is a significant risk factor for ingestion of marine debris by small odontocetes, results of monitoring programmes may be biased by the prevalence of CNS disease in a specific area or population.
... Regardless to prey resemblance, debris coloration and brightness alters the conspicuousness of plastics to visual foragers (see Santos et al., 2016), which also influence the chance of ingestion. The likelihood of plastic ingestion in the ocean is also closely linked to the habitat use and opportunistic foraging behaviors of seabirds (Caldwell et al., 2019;Wilcox et al., 2015), sea turtles (Andrades et al., 2019;Santos et al., 2015a) and marine mammals (Alexiadou et al., 2019;Denuncio et al., 2011Denuncio et al., , 2017. ...
Article
In the last decade many studies have described the ingestion of plastic in marine animals. While most studies were dedicated to understanding the pre-ingestion processes involving decision-making foraging choices based on visual and olfactory cues of animals, our knowledge in the post-ingestion consequences remains limited. Here we proposed a theoretical complementary view of post-ingestion consequences, attempting to connect plastic ingestion with plastic-induced satiety. We analyzed data of plastic ingestion and dietary information of 223 immature green turtles (Chelonia mydas) from tropical Brazilian reefs in order to understand the impacts of plastic ingestion on foraging behavior. Generalized linear mixing models and permutational analysis of variance suggested that plastic accumulations in esophagus, stomach and intestine differed in their impact on green turtle's food intake. At the initial stages of plastic ingestion, where the plastic still in the stomach, an increase in food intake was observed. The accumulation of plastic in the gastrointestinal tract can reduce food intake likely leading to plastic-induced satiety. Our results also suggest that higher amounts of plastics in the gastrointestinal tract may led to underweight and emaciated turtles. We hope that adopting and refining our proposed framework will help to clarify the post-ingestion consequences of plastic ingestion in wildlife.
... The Hellenic Trench and the Aegean Sea are notable exceptions where systematic surveys have been conducted since the early 1990s (Frantzis 1996;Öztürk and Öztürk 1998;Frantzis et al. 1999Frantzis et al. , 2001Frantzis et al. , 2003Frantzis et al. , 2014Carpentieri et al. 1999;Altuğ et al. 2011;Cañadas and Notarbartolo di Sciara 2018). Recent surveys mainly focused on the effects of marine pollution on cetaceans within the Eastern Mediterranean (Shoham-Frider et al. 2016;Bigal et al. 2018;Marsili et al. 2018;Alexiadou et al. 2019). Each of the aforementioned studies have highlighted that despite the scarce dedicated survey effort, Eastern Mediterranean Sea is likely to hold potential important habitats for cetaceans yet to be discovered (Goffman et al. 2000;Dede et al. 2016;Kerem et al. 2012;Bigal et al. 2018;Farrag et al. 2019). ...
Article
Lack of baseline knowledge is often the principal conservation barrier, especially if the species of concern shows steady decline. The primary goal of the current project is to fill the knowledge gaps in understudied cetacean populations through dedicated visual and acoustic surveys in the Eastern Mediterranean Sea of Turkey. The surveys were conducted over six seasons, following 4384.76 km in 49 days between April 2018 and July 2019. Cetaceans were detected on 39 days (146 sightings), with the highest sightings belonging to delphinids (bottlenose, common and unidentified dolphins) followed by sperm whales (Physeter macrocephalus) and a single acoustic detection of a beaked whale. Fethiye Canyon held the highest cetacean concentration and thus is identified as an "important habitat". Reported encounter rates were higher than previous studies, with 2.78 and 0.55 groups/100 km for delphinids and sperm whales, respectively. Despite the lack of significant variation in cetacean presence due to season and diurnal effects, there was a noticeable increase in summer sightings for sperm whales, where they were encountered as solitary individuals and social units with calves. The current research presented the first seasonal survey results of the Turkish Mediterranean and underlines the importance of local research efforts for valid conclusions in an understudied environment that holds not only unrecognized cetacean habitats but also a wide range of human pressures.
... Where plastic bags were common, they were abundant in nearby land and seafloor sites, potentially due to their propensity to become entangled or snagged. Plastic bags are particularly dangerous for marine animals and have caused mortality following entanglement (Green et al., 2015) and ingestion in wildlife, particularly among sea turtles (Schuyler et al., 2012) and marine mammals (Alexiadou et al., 2019;De Stephanis et al., 2013). Plastic bags are also regularly reported in the stomachs of dead marine animals such as whales and dolphins (De Stephanis et al., 2013;Panti et al., 2019). ...
Article
Full-text available
Pollution of coastal and marine environments by mismanaged anthropogenic debris is a global threat requiring complex, multilateral solutions and mitigation strategies. International efforts to catalogue and quantify the density, extent and nature of mismanaged waste have not yet assessed the heterogeneity of debris between nearby areas. Better understanding of how debris types and density can be used as a proxy between regions and between land and seafloor habitats at a global scale can aid in developing cost effective and representative debris monitoring systems. Using volunteer collected clean-up and survey data, we compared the proportion and density of both total debris and specific items across 19,428 coastal land and seafloor sites from International Coastal Clean-ups and Dive Against Debris surveys, from 86 countries between 2011 and 2018. We show that although some items common on land are also common on the seafloor, there is an overall global mismatch between debris types and densities on land and the seafloor from nearby areas. Correlations in land/seafloor debris type/density occurred primarily for items which entangle and/or sink, including fishing line, plastic bags, glass and polyethylene terephthalate (PET) bottles. Minimal similarity between land and seafloor surveys occurs for items which float or degrade. We suggest that to accurately evaluate local debris density, land and seafloor surveys are required to gain a holistic understanding. When detailed information on debris type, relative concentration, and likely source and transport are assessed, more cost effective and efficient policy interventions can be designed and implemented from local through to global scales.
... Sea turtles and cetaceans are among one of the most susceptible species against plastic pollution. Numerous studies were performed on stranded turtles and cetaceans and plastics appeared to be the leading cause of mortality by gastric blockage (Alexiadou, Foskolos, & Frantzis, 2019;Nelms et al., 2019;Poli, Mesquita, Saska, & Mascarenhas, 2015). The animals that feed on plastics are also die from starvation because the plastic occupies space in the stomach and creates a false sense of satiety (Jovanović, 2018), while the animal stomach contains no food. ...
Article
The plastic litter in the seas and oceans has become one of the major threats for environment and a wide range of marine species worldwide. Microplastics are the most common litters in the marine environment corresponding to 60-80% of the total litter in the world’s seas. The risk factor of plastics is inversely associated with the size of the plastic. In the present study, we reviewed the state of knowledge regarding the impact of plastic pollution on marine environment and marine species, assessing the ingestion incidences, elimination of plastics, interactions of plastics with other pollutants, and effects on photosynthesis. Records of marine species ingesting plastic have increased and begin to attract considerable attention. Metadata generated from the review of related papers in the present study was used to evaluate the current knowledge on the plastic ingestion by different marine species. The retrieved data from reviewed articles revealed that the ingestion of plastic by marine animals have been documented in more than 560 species including fish, crustaceans, mammals, sea turtles, bivalves, gastropods even in sea stars and limpets. The size of ingested plastics varied from species to species generally depending on the feeding behavior. Microplastics showed the highest number of bibliographic citations in the plastic ingestion studies. They are mostly ingested by planktivorous and filter feeder species. Meso, macro, and occasionally megaplastics are reported in marine mammals and sea turtles since they often confuse plastic for their prey. The sensitivity and size of the detected plastics may vary based on the analytical plastic detection methods.
... For example, some seabirds were entangled by fish gear, resulting in fatal harm (Donnelly-Greenan et al. 2019). Ingestion of plastic debris can not only cause the death of large animals due to intestinal blockage or gastric impaction (Alexiadou et al. 2019), but also lead to chronic impacts with the potential accumulation along the food chain (Wright et al. 2013). Jacobsen et al. (2010) revealed that two male sperm whales succumb to ruptured stomach and gastric impaction, induced by the presence of numerous plastic debris. ...
Article
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Plastics are ubiquitous in the environment and have become a hot topic in academic circles. Extensive studies have focused on analytical methods, source, abundance, transport, fate, degradation of plastics in the environment and threats to natural surroundings, wildlife or even human health. However, characteristics of plastic pollution, which are critical to understand this emerging problem, remain unknown up to now. Here, this paper reviews the major characteristics of plastic pollution in the environment to enhance present understanding of this issue. These characteristics, including diversity, persistence, global issues, combined pollution and threats to organisms and human health, are critically summarized in this work. Further, “plastic cycle” in the environment, namely, aquatic, atmospheric, and terrestrial system, is also discussed in this review. Finally, we highlight current challenges of plastic pollution posed to the public and also recommend the research trends in future work.
... It is estimated that, annually, between 1 and 12 million pieces of anthropogenic debris enter the ocean via rivers (Jambeck et al., 2015;Lebreton et al., 2017), being the plastic between 60 and 80% of the anthropogenic debris found in the ocean (Derraik, 2002). The presence of debris in the environment has negative impacts on various animal species (Lusher et al., 2015;Rochman et al., 2015;de Carvalho-Souza et al., 2018), such as entanglement and suffocation of turtles (Duncan et al., 2017;Staffieri et al., 2019), seabirds (Ryan, 2018) and mammals (Stelfox et al., 2016;Poeta et al., 2017) or ingestion of anthropogenic material by various species from the trophic chain, such as seabirds (Furness, 1985;Ryan, 1987;Petry et al., 2009;Petry and Benemann, 2017;Battisti et al., 2019) and marine mammals (Alexiadou et al., 2019;Brentano and Petry, 2020). ...
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... However, it is also possible that the negative correlation identified for PA is related to dietary differences, and thus exposure, among animals with smaller and larger body mass and length. Recent studies have shown that newborn harbor porpoises (smaller body mass and length) stranded in the Netherlands and the Aegean Sea in Greece did not have any plastic debris in their stomach (Alexiadou et al., 2019;van Franeker et al., 2018). However, van Franeker et al. (2018) found no differences between juveniles and adults, nor between the sexes with respect to frequencies of occurrence of plastic litter in their stomachs (and thus potentially plasticizers such as phthalates). ...
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The exposure of marine mammals to phthalates has received considerable attention due to the ubiquitous occurrence of these pollutants in the marine environment and their potential adverse health effects. The occurrence of phthalate metabolites is well established in human populations, but data is scarce for marine mammals. In this study, concentrations of 17 phthalate metabolites were determined in liver samples collected from one hundred (n = 100) by-caught harbor porpoises (Phocoena phocoena) along the coast of Norway. Overall, thirteen phthalate metabolites were detected in the samples. Monoethyl phthalate (mEP), mono-iso-butyl phthalate (mIBP), mono-n-butyl phthalate (mBP) and phthalic acid (PA) were the most abundant metabolites, accounting for detection rates ≥ 85%. The highest median concentrations were found for mIBP (30.6 ng/g wet weight [w.w.]) and mBP (25.2 ng/g w.w.) followed by PA (7.75 ng/g w.w.) and mEP (5.67 ng/g w.w.). The sum of the median phthalate metabolites concentrations that were found in the majority of samples (detection rates > 50%) indicated that concentrations were lower for porpoises collected along the coastal area of Bodø (Nordland), Lebesby (Finnmark) and Varangerfjord (as compared to other coastal areas); these areas are among the least populated coastal areas but also the most distant (> 700 km) from offshore active oil and gas fields. The monomethyl phthalate metabolite (mMP) was detected in 69% of the samples, and to our knowledge, alongside with PA, this is the first report of their occurrence in marine mammals. PA, as the non-specific marker of phthalate exposures, showed a statistically significant negative association with the body mass and length of the harbor porpoises. Among the phthalate metabolites, statistically significant positive associations were found between mBP and mIBP, mMP and mEP, PA and mEP, mIBP and mono(2-ethyl-5-oxohexyl) phthalate (mEOHP), mIBP and mono(2-ethyl-5-hydroxyhexyl) phthalate (mEHHP), mBP and mEHHP, mono-n-nonyl phthalate (mNP) and PA, and between monobenzyl phthalate (mBzP) and mNP. To our knowledge, this is the first study on the biomonitoring of 17 phthalate metabolites in harbor porpoises.
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The Finike Seamounts (Anaximander) was declared as the "Finike Seamounts Special Environmental Protection Area (SEPA)" by Republic of Türkiye in 2013. In order to determine the presence of cetaceans living in the region and its adjacent waters, visual observations were carried out with the standard line transect method as well as passive acoustic recordings at 21 stations in two boat surveys in spring and autumn 2021. A total of 1621 nautical miles were covered in both surveys. Sperm whales were detected visually and acoustically. Other deep-diving species, Cuvier's beaked whale, was observed once, as well as delphinid species, such as the striped dolphins (two groups) and bottlenose dolphins (7 groups). Delphinids were also detected acoustically in 8 stations. Although the surveys were made only in two seasons in one year, it was shown that the cetaceans use the surveyed area and their presence must be taken into consideration in the management of the Finike Seamounts SEPA.
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Chapter
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Plastic Pollution and Marine Conservation: Approaches to Protect Biodiversity and Marine Life provides comprehensive knowledge on the consequences of plastic waste in marine environments at different levels, ranging from ecological and biological, to social, economic and political. The book synthesizes historical information, gaps in current knowledge, and recent discoveries by illustrating the main stages that made plastics a global issue for ocean ecosystems and their wildlife. Written by international experts on marine pollution, marine biology, and management of environmental resources, this book explores the main topics of marine plastic pollution such as input quantification, polluting sources, ultimate fate, ecological consequences, and more. This an important resource for a wide audience, including marine conservationists, environmental managers, decision-makers, NGOs, private companies, and activists working to combat plastics in our seas and oceans. https://www.elsevier.com/books/Plastic%20Pollution%20and%20Marine%20Conservation/9780128224717?utm_campaign=BookRelease_Email1_ELS&utm_medium=email&utm_acid=93990062&SIS_ID=&dgcid=BookRelease_Email1_ELS&CMX_ID=&utm_in=DM217799&utm_source=AC_
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Thesis
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Η παρούσα εργασία καταγράφει και περιγράφει τις τεχνικές παρακολούθησης που εφαρμόζονται στην σύγχρονη επιστημονική έρευνα για τα κητώδη, με ειδίκευση τη συλλογή δεδομένων για την εκτίμηση των πληθυσμών και της κατανομής των ειδών. Βασική μεθοδολογία για τη συγγραφή της αποτέλεσε η διεξοδική μελέτη της πρόσφατης βιβλιογραφίας στο πεδίο της επιστήμης των θαλάσσιων θηλαστικών. Η εργασία χωρίζεται σε τέσσερα κεφάλαια. Στο πρώτο κεφάλαιο αποτυπώνονται τα γενικά στοιχεία γύρω από τα κητώδη. Περιγράφονται βασικά βιολογικά και οικολογικά χαρακτηριστικά των κητωδών και γίνεται λόγος για την συμβολή τους στα οικοσυστήματα και την αξία τους γενικότερα. Το κεφάλαιο κλείνει με μια αναδρομή στη σχέση του ανθρώπου με τα κητώδη από την εποχή της φαλαινοθηρίας στις σημερινές προσπάθειες προστασίας. Το δεύτερο κεφάλαιο περιγράφει τις σημαντικότερες τεχνικές παρακολούθησης της αφθονίας και της κατανομής των κητωδών. Με βάση τα τεχνικά μέσα και τον τρόπο που χρησιμοποιούνται για τη δειγματοληψία των δεδομένων, διακρίνονται πέντε τεχνικές και επεξηγούνται τα βασικά χαρακτηριστικά, τα πλεονεκτήματα, τα μειονεκτήματα και η μελλοντική τους βελτίωση. Στο τρίτο κεφάλαιο παρουσιάζεται η σημερινή γνώση της αφθονίας και της κατανομής των ειδών στη Μεσόγειο και τη Μαύρη θάλασσα, με βάση τα αποτελέσματα των επιστημονικών ερευνών τις τελευταίες δεκαετίες. Αναφέρονται παραδείγματα από τις έρευνες για κάθε είδος ξεχωριστά και οι συγκεκριμένες τεχνικές που εφαρμόστηκαν. Τέλος, στο τέταρτο κεφάλαιο παρατίθενται τα συμπεράσματα που προκύπτουν από το σύνολο της εργασίας και η συζήτηση για την αποτελεσματική προστασία και διατήρηση των κητωδών που παραμένει ανοικτή.
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We reviewed the environmental impacts of microplastics, discussed the dynamics of microplastics in the aquatic environment and their impacts on marine ecosystems, and introduced the latest analytical methods for microplastics, especially for samples with small particle sizes. Regarding the situation of microplastics in land areas and rivers, the numerical and mass concentrations of microplastics in rivers all over Japan and the estimated total amount of plastics discharged from Japan’s land areas to the ocean were determined. Regarding the state of microplastics in the sea, the dynamics of microplastics in Tokyo Bay and the uptake of microplastics by marine life were determined. For the analysis of microplastics, the methods of sampling, pretreatment, and equipment measurement and their ploblems were summarized, and a technical perspective was presented. It is essential to clarify the dynamics of microplastics in the environment and their impact on ecosystems in order to plan effective and efficient measures for the proper use and management of plastics in the social system. We hope that the information introduced in this paper will contribute to these activities.
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Cuvier's beaked whales exhibit exceptionally long and deep foraging dives. The species is little studied due to their deep-water, offshore distribution and limited time spent at the surface. We used LIMPET satellite tags to study the diving behaviour of Cuvier's beaked whales off Cape Hatteras, North Carolina from 2014 to 2016. We deployed 11 tags, recording 3242 h of behaviour data, encompassing 5926 dives. Dive types were highly bimodal; deep dives (greater than 800 m, n = 1408) had a median depth of 1456 m and median duration of 58.9 min; shallow dives (50–800 m, n = 4518) were to median depths of 280 m with a median duration of 18.7 min. Most surface intervals were very short (median 2.2 min), but all animals occasionally performed extended surface intervals. We found no diel differences in dive depth or the percentage of time spent deep diving, but whales spent significantly more time near the surface at night. Other populations of this species exhibit similar dive patterns, but with regional differences in depth, duration and inter-dive intervals. Satellite-linked tags allow for the collection of long periods of dive records, including the occurrence of anomalous behaviours, bringing new insights into the lives of these deep divers.
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The Mediterranean sperm whale population is listed as ‘Endangered”. The Hellenic Trench is the core habitat of the eastern Mediterranean sperm whale sub-population that numbers two to three hundred individuals. Major shipping routes running on or very close to the 1000 m depth contour along the Hellenic Trench are causing an unsustainable number of ship-strikes with sperm whales reviewed in this paper. Sperm whale sighting and density data were combined with specific information on the vessel traffic in the area (e.g., types of vessels, traffic patterns, speed and traffic density), in order to estimate the risk of a whale/ship interaction. Routing options to significantly reduce ship strike risk by a small offshore shift in shipping routes were identified. The overall collision risk for sperm whales in the study area would be reduced by around 70%, while a maximum of 11 nautical miles would be added to major routes and only around 5 nautical miles for the majority of ships. No negative impacts were associated with re-routing by shipping away from sperm whale habitat and there would be additional shipping safety and environmental benefits. A significant contribution to the overall conservation status of the marine Natura2000 sites in the area and very important population units of threatened species such as Cuvier’s beaked whales, monk seals and loggerhead turtles would be achieved, by the reduction of shipping noise and reduced risk of any oil spills reaching the coasts, which are also important touristic destinations in Greece.
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Plastic pollution represents a pervasive and increasing threat to marine ecosystems worldwide and there is a need to better understand the extent to which microplastics (<5 mm) are ingested by high trophic-level taxa, such as marine mammals. Here, we perform a comprehensive assessment by examining whole digestive tracts of 50 individuals from 10 species whilst operating strict contamination controls. Microplastics were ubiquitous with particles detected in every animal examined. The relatively low number per animal (mean = 5.5) suggests these particles are transitory. Stomachs, however, were found to contain a greater number than intestines, indicating a potential site of temporary retention. The majority of particles were fibres (84%) while the remaining 16% was fragments. Particles were mainly blue and black (42.5% and 26.4%) in colour and Nylon was the most prevalent (60%) polymer type. A possible relationship was found between the cause of death category and microplastic abundance, indicating that animals that died due to infectious diseases had a slightly higher number of particles than those that died of trauma and other drivers of mortality. It is not possible, however, to draw any firm conclusions on the potential biological significance of this observation and further research is required to better understand the potential chronic effects of microplastic exposure on animal health, particularly as marine mammals are widely considered important sentinels for the implications of pollution for the marine environment.
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Mass strandings of sperm whales (Physeter macrocephalus) are rare in the Mediterranean Sea. Nevertheless, in 2014 a pod of 7 specimens stranded alive along the Italian coast of the Central Adriatic Sea: 3 individuals died on the beach after a few hours due to internal damages induced by prolonged recumbency; the remaining 4 whales were refloated after great efforts. All the dead animals were genetically related females; one was pregnant. All the animals were infected by dolphin morbillivirus (DMV) and the pregnant whale was also affected by a severe nephropathy due to a large kidney stone. Other analyses ruled out other possible relevant factors related to weather conditions or human activities. The results of multidisciplinary post-mortem analyses revealed that the 7 sperm whales entered the Adriatic Sea encountering adverse weather conditions and then kept heading northward following the pregnant but sick leader of the pod, thereby reaching the stranding site. DMV infection most likely played a crucial role in impairing the health condition and orientation abilities of the whales. They did not steer back towards deeper waters, but eventually stranded along the Central Adriatic Sea coastline, a real trap for sperm whales.
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This study reports plastic debris pollution in the deep-sea based on the information from a recently developed database. The Global Oceanographic Data Center (GODAC) of the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) launched the Deep-sea Debris Database for public use in March 2017. The database archives photographs and videos of debris that have been collected since 1983 by deep-sea submersibles and remotely operated vehicles. From the 5010 dives in the database, 3425 man-made debris items were counted. More than 33% of the debris was macro-plastic, of which 89% was single-use products, and these ratios increased to 52% and 92%, respectively, in areas deeper than 6000 m. The deepest record was a plastic bag at 10898 m in the Mariana Trench. Deep-sea organisms were observed in the 17% of plastic debris images, which include entanglement of plastic bags on chemosynthetic cold seep communities. Quantitative density analysis for the subset data in the western North Pacific showed plastic density ranging from 17 to 335 items km⁻² at depths of 1092–5977 m. The data show that, in addition to resource exploitation and industrial development, the influence of land-based human activities has reached the deepest parts of the ocean in areas more than 1000 km from the mainland. Establishment of international frameworks on monitoring of deep-sea plastic pollution as an Essential Ocean Variable and a data sharing protocol are the keys to delivering scientific outcomes that are useful for the effective management of plastic pollution and the conservation of deep-sea ecosystems.
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Stomach contents of harbour porpoises (Phocoena phocoena) collected in the Netherlands between 2003 and 2013 were inspected for the presence of plastic and other man-made litter. In 654 stomach samples the frequency of occurrence of plastic litter was 7% with less than 0.5% additional presence of nonsynthetic man-made litter. However, we show that when a dedicated standard protocol for the detection of litter is followed, a considerably higher percentage (15% of 81 harbour porpoise stomachs from the period 2010–2013) contained plastic litter. Results thus strongly depended on methods used and time period considered. Occurrence of litter in the stomach was correlated to the presence of other non-food remains like stones, shells, bog-wood, etc., suggesting that litter was often ingested accidentally when the animals foraged close to the bottom. Most items were small and were not considered to have had a major health impact. No evident differences in ingestion were found between sexes or age groups, with the exception that neonates contained no litter. Polyethylene and polypropylene were the most common plastic types encountered. Compared to earlier literature on the harbour porpoise and related species, our results suggest higher levels of ingestion of litter. This is largely due to the lack of dedicated protocols to investigate marine litter ingestion in previous studies. Still, the low frequency of ingestion, and minor number and mass of litter items found in harbour porpoises in the relatively polluted southern North Sea indicates that the species is not a strong candidate for annual monitoring of marine litter trends under the EU marine strategy framework directive. However, for longerterm comparisons and regional differences, with proper dedicated protocols applied, the harbour porpoise has specific use in quantifying litter presence in the, for that specific objective, poorly studied benthic marine habitat.
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Cetacean stranding reports in the North Aegean Sea were recorded since 1998 from Strimonikos Gulf in Chalkidiki up to Alexandroupoli on the Turkish border and in a few northern Aegean islands. On site, the specimens were examined to identify species, gender, approximate age and, when possible, cause for stranding. A total of 26 filled stomachs of five cetacean species collected since 2002 were analysed: bottlenose dolphins Tursiops truncatus (N = 8), common dolphins Delphinus delphis (N = 8), harbour porpoises Phocoena phocoena (N = 5), striped dolphins Stenella coeruleoalba (N = 4) and Risso's dolphins Grampus griseus (N = 1). From the analysed stomachs it was found that the bottlenose dolphins fed mainly on snake blenny Ophidion barbatum (34%), bogue Boops boops (22%) and round sardinella Sardinella aurita (13%); common dolphins on round sardinella (17%), picarels Spicara spp. (10%) and Cocco's lantern fish Lobianchia gemellaris (9%); harbour porpoises on Gobidae (four-spotted goby Deltentosteus quadrimaculatus 41% and black goby Gobius niger 37%) and round sardinella (7%); striped dolphins on Myctophydae (Madeira lantern fish Ceratoscopelus maderensis 51%), and on Pfeffer's enople squid Abraliopsis morisii (10%) and bogue (8%); and Risso's dolphin exclusively on Teuthidae (31%), the umbrella squid Histioteuthis bonellii (30%) and the reverse jewel squid H. reversa (14%). The present work represents the first attempt to investigate the diet up to species level for several cetaceans in Greek waters and for harbour porpoises stranded in the Mediterranean Sea.
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Plastic pollution has become one of the largest environmental challenges we currently face. The United Nations Environment Program (UNEP) has listed it as a critical problem, comparable to climate change, demonstrating both the scale and degree of the environmental problem. Mortalities due to entanglement in plastic fishing nets and bags have been reported for marine mammals, turtles and seabirds, and to date over 690 marine species have been reported to ingest plastics. The body of literature documenting plastic ingestion by marine megafauna (i.e. seabirds, turtles, fish and marine mammals) has grown rapidly over the last decade, and it is expected to continue grow as researchers explore the ecological impacts of marine pollution. Unfortunately, a cohesive approach by the scientific community to quantify plastic ingestion by wildlife is lacking, which is now hindering spatial and temporal comparisons between and among species/ organisms. Here, we discuss and propose standardized techniques, approaches and metrics for reporting debris ingestion that are applicable to most large marine vertebrates. As a case study, we examine how the use of standardized methods to report ingested debris in Northern Fulmars (Fulmarus glacialis) has enabled long term and spatial trends in plastic pollution to be studied. Lastly, we outline standardized metric recommendations for reporting ingested plastics in marine megafauna, with the aim to harmonize the data that are available to facilitate large-scale comparisons and meta-analyses of plastic accumulation in a variety of taxa. If standardized methods are adopted, future plastic ingestion research will be better able to inform questions related to the impacts of plastics across taxonomic, ecosystem and spatial scales.