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Abstract

Anthropogenic debris ingestion has been reported for green turtles in all their life stages worldwide. The aim of the present study is to evaluate the marine debris ingestion by green turtles stranded in Uruguayan coast between 2005 and 2013. Debris items were categorized and quantified by frequency of occurrence, relative weight, volume and number of items. A total of 96 dead stranded turtles were analyzed and 70% presented debris in their guts. The majority of debris found were plastic, being hard plastics the most abundant in weight and volume. The best model explaining the variability of the amount of debris ingested included turtle size, Julian day and distance from the estuary. We detected a negative correlation between the presence of debris and turtle's size. Smaller turtles are new recruits to neritic grounds indicating that the early juvenile stage of this species is the most vulnerable to this threat in the Southwestern Atlantic.

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... In addition, knowledge on how individuals and populations use space over time can be fundamental to identify critical habitats, resources, migratory pathways (Musick & Limpus 1997, Bolten 2003, Meylan et al. 2011, baseline and shifts in growth rates (Diez & van Dam 2002, Bjorndal et al. 2013, 2016, Murakawa & Snover 2018, as well as the cumulative impacts of threats (Bolten et al. 2011) and areas of refuge (Maxwell et al. 2013, Halpern et al. 2015. For example, cumulative survival can be influenced by life stage duration, with varying exposure to stage-and habitat-specific threats (Frazer 1986, Sasso & Epperly 2007, Turner-Tomaszewicz et al. 2015, Vélez-Rubio et al. 2018). In addition, building a strong ecological baseline will provide better and more efficient opportunities to tackle sudden catastrophes and threats, such as the 2010 BP Deepwater Horizon oil spill in the Gulf of Mexico (Bjorndal et al. 2011). ...
... Prioritizing research in the Indian Ocean region is of special significance, given that it is a critical area of concern for sea turtles because of the high rate of bycatch and illegal fishing (Riskas et al. 2018, Temple et al. 2018. Across all regions, immature turtles are also increasingly facing local and global threats such as plastic pollution (Boyle et al. 2009, González-Carman et al. 2014, Santos et al. 2015, Nelms et al. 2016a, Schuyler et al. 2016, Duncan et al. 2017, Vélez-Rubio et al. 2018, seismic surveys (Nelms et al. 2016b), and port and dredging activities (Goldberg et al. 2015, Gama et al. 2016. Furthermore, the cumulative impact of anthropogenic stressors on oceanic environments is increasing at multiple sites within the Indian Ocean (e.g. ...
... al. 2013,Williams et al. 2017, Williard et al. 2017, genetics(Bjorndal & Bolten 2008, Jensen et al. 2016a,b, 2018, Naro-Maciel et al. 2017, diet preferences, and trophic levels showing an ontogenetic shift from omnivore to herbivore(Bjorndal 1997, Fuentes et al. 2006, Cardona et al. 2010, González-Carman et al. 2012a, Vander Zanden et al. 2013a,b, Morais et al. 2014, Gama et al. 2016, Vélez-Rubio et al. 2018, growth rates(Limpus & Chaloupka 1997, Bjorndal et al. 2000, Zug et al. 2002, Kubis et al. 2009, Goshe et al. 2010, Avens et al. 2012, Lenz et al. 2017, health assessments (e.g. fibropapillomatosis;Coberley et al. 2001, dos Santos et al. 2010, Hirama et al. 2014, Santos et al. 2015, Jones et al. 2016, Balladares et al. 2017, and the effect of human activities (e.g. ...
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Sea turtle research has received substantial focus worldwide. However, research on the immature life stages of sea turtles is still relatively limited. The latter is of particular importance, given that a large proportion of sea turtle populations comprises immature individuals. We set out to identify knowledge gaps in immature sea turtle research, and identify the main barriers hindering research in this field. We analyzed the perceptions of sea turtle experts through an online survey which gathered their opinion on the current state of affairs on immature sea turtle research, including species and regions in need of further study, priority research questions, and barriers that have interfered with the advancement of research. Our gap analysis indicates that studies on immature individuals of the leatherback Dermochelys coriacea and hawksbill Eretmochelys imbricata turtles are lacking, as well as studies on all species based in the Indian, South Pacific and South Atlantic Oceans. Experts also perceived that studies in population ecology, namely survivorship and demographic studies, and habitat use/behavior, are needed to advance the state of knowledge on immature sea turtles. Our survey findings indicate the need for more inter-disciplinary research, collaborative efforts (e.g., data-sharing, joint field activities), improved communication among researchers, funding bodies, stakeholders, and decision-makers on the importance of supporting research on immature sea turtles.
... The data here indicate a relatively greater frequency of marinedebris intake by C. mydas (92% of the total sampled) than observed during previous studies in the SWAO (Gama et al., 2016;Guebert-Bartholo et al., 2011;Santos et al., 2016;Vélez-Rubio et al., 2015). Similarly, the mean amounts of ingested debris (mean ± SE of 116.35 ± 198.95) exceeded those recently found for similar-sized C. mydas in the Mediterranean Sea (61.8 ± 15.8 items among specimens with a mean CCL of 36.9 ± 14.2 cm; Duncan et al., 2019) and Pacific Ocean (93.8 ± 83.6 items, and specimens measuring 43.9 ± 5.2 cm straight carapace length; Clukey et al., 2017), but were lower than values among conspecifics stranded off Uruguay (220.7 ± 320.8 items and 40.1 ± 6.7 cm Table 1 Number -Rubio et al., 2018b). Reasons for such variability in ingestion may range from regional debris availability to intra-specific genetic variation among stocks and feeding habitats (Coelho et al., 2018;Galgani et al., 2015;Vélez-Rubio et al., 2018b). ...
... Similarly, the mean amounts of ingested debris (mean ± SE of 116.35 ± 198.95) exceeded those recently found for similar-sized C. mydas in the Mediterranean Sea (61.8 ± 15.8 items among specimens with a mean CCL of 36.9 ± 14.2 cm; Duncan et al., 2019) and Pacific Ocean (93.8 ± 83.6 items, and specimens measuring 43.9 ± 5.2 cm straight carapace length; Clukey et al., 2017), but were lower than values among conspecifics stranded off Uruguay (220.7 ± 320.8 items and 40.1 ± 6.7 cm Table 1 Number -Rubio et al., 2018b). Reasons for such variability in ingestion may range from regional debris availability to intra-specific genetic variation among stocks and feeding habitats (Coelho et al., 2018;Galgani et al., 2015;Vélez-Rubio et al., 2018b). But it is important to note that there is considerable individual variation among the amounts of marine debris ingested, making it difficult to compare studies using only average values. ...
... Considering the entire digestive tract, it is apparent small C. mydas off Paraná had relatively greater proportions of marine debris per contents than their larger conspecifics. Similar results also have been reported in other studies and may be a consequence of a more generalist diet during the ontogenetic process (Duncan et al., 2019;Gama et al., 2016;Vélez-Rubio et al., 2018b). Conversely, larger turtles have a proportionally greater internal diameter of their digestive tract, better facilitating debris excretion (Schuyler et al., 2012). ...
Article
Beaches in southern Brazil have substantial marine debris and strandings of dead juvenile green turtles (Chelonia mydas). This study investigates associations by quantifying marine debris (1) ingested among new (<40 cm curved carapace length; CCL) and older (≥40 cm CCL) juvenile C. mydas recruits; (2) concentrations on beach transects; and then (3) selective ingestion by C. mydas. Among 40 C. mydas (2014–2015), 93% had ingested debris, with smaller individuals having proportionally more. Sheet-like and hard plastics were the most frequently ingested, and commonly concentrated on beach transects. Estuarine beach transects had more debris than those facing the ocean. Selectivity analyses revealed all C. mydas avoided white miscellaneous debris and straws, while smaller conspecifics selected clear sheet-like plastics and avoided coloured ones. The results reiterate a need for long-term reforms to regional waste disposal and short-term initiatives encouraging social awareness to avoid key plastics and reduce ingestion by C. mydas.
... In any case, juvenile green turtles at the region are considered in a general manner opportunistic, which may result in their high interaction with PML: previous reported FO% ingestion values for southern Brazil were 60.5% (only esophagus and stomach evaluated; Bugoni et al., 2001), 100% (Tourinho et al., 2010) and 72.6% (Colferai et al., 2017). Juvenile and adult green turtles at other areas in Brazil as well as Uruguay also present high FO% of PML ingestion, ranging from 70 to 100% (Carman et al., 2014;Santos et al., 2015;Vélez-Rubio et al., 2018). In the North Pacific, between 90 and 100% of sampled green turtles have been shown to ingest PML (Wedemeyer-Strombel et al., 2015;Fukuoka et al., 2016;Clukey et al., 2017). ...
... Plastic fragments were the most frequently and abundantly ingested litter by sea turtles in this study, in accordance with the worldwide pattern (Schuyler et al., 2014a(Schuyler et al., , 2016Santos et al., 2015;Clukey et al., 2017). The main items found in the GITs of the animals analysed were hard and flexible fragments, packaging, bags and lines, which are also the most common types of plastics ingested by sea turtles globally (Schuyler et al., 2014a;Clukey et al., 2017;Colferai et al., 2017;Pham et al., 2017;Vélez-Rubio et al., 2018). Other plastics, such as PS, ribbons, entangled wires and fibers, also occur in the GITs of green turtles. ...
... However, it is evident that in the area covered by this study, green turtles are under constant threat from PML ingestion, presenting ingestion frequencies equal to or above 70% for most analysed years. At the coast of Uruguay the FO% of PML ingestion by juvenile green turtles has also been high over the years (2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013), but with an increase in ingested mass and volume (Vélez-Rubio et al., 2018). The constant and abundant ingestion of PML by this species, as well as the apparent increase in the amount of PML ingestion, is concerning. ...
... There are reports of marine animals ingesting detritus in various regions of the world, such as the east coast of North America, Australasia, the west coast of North America, Europe, Antarctica, the east and west coasts of Africa, the west coast of South America and the Arctic (Gall and Thompson, 2015). On the coast of South America, there are reports of green turtles, on the Uruguaiana coast (Vélez-Rubio et al., 2018), Rio de la Plata (Argentina-Uruguay) (Carman et al., 2013) and southern Brazil (Tourinho et al., 2010). This is attributed to the similarity of these materials with algae and corals, the natural food of these animals, or when precipitated with algae (Caron et al., 2018). ...
... Regarding the curvilinear length of the carapace, the group that ingested inorganic detritus presented a mean of 7.7 cm less than the group that did not ingest, similar to Colferai et al. (2017) and Vélez-Rubio et al. (2018). But these results diverged from other studies (Bugoni et al., 2001;Casale et al., 2016;Tourinho et al., 2010). ...
... Casale et al. (2016),Colferai et al. (2017),Jerdy et al. (2017),Tourinho et al. (2010) andVélez-Rubio et al. (2018). The lowest rates were found via diagnosis by endoscopic examination, that visualizes the initial portions of the gastrointestinal tract, but almost 70% of the ingested detritus stay in the intestines (Guebert-Bartholo et al., 2011). ...
... It is thought to occur in at least 43% of cetacean species, 36% of the seabird species, many species of fish and has been reported in all species of marine turtle 7-10 . Plastics are the most commonly ingested of all anthropogenic debris; with a wide variety of items found inside necropsied sea turtles [11][12][13][14][15] . This has the potential to cause lethal effects from intestinal blockage and injury but additionally adverse sub-lethal effects such as dietary dilution, malnutrition and impaired immunity 9 . ...
... When attempting to understand reasons for plastic ingestion it is important to consider the feeding ecology of marine turtles 11,15,19 . Consumption of plastic may be due to a failure of discrimination when mixed with normal dietary items. ...
... It is important to note, however, that indirect ingestion of macroplastic through trophic transfer cannot be completely ruled out. Gelatinous macrozooplankton still make up a major component of the diet of neritic juvenile green turtles in the western Atlantic 15 . Macroplastic ingestion has been recently reported in such organisms providing potential trophic transfer of macroplastic pieces to marine turtles when prey is consumed suspended in the water column 41 . ...
Article
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Understanding the drivers of key interactions between marine vertebrates and plastic pollution is now considered a research priority. Sea turtles are primarily visual predators, with the ability to discriminate according to colour and shape; therefore these factors play a role in feeding choices. Classification methodologies of ingested plastic currently do not record these variables, however here, refined protocols allow us to test the hypothesis that plastic is selectively ingested when it resembles the food items of green turtles (Chelonia mydas). Turtles in the eastern Mediterranean displayed strong diet-related selectivity towards certain types (sheet and threadlike), colours (black, clear and green) and shapes (linear items strongly preferred) of plastic when compared to the environmental baseline of plastic beach debris. There was a significant negative relationship between size of turtle (curved carapace length) and number/mass of plastic pieces ingested, which may be explained through naivety and/or ontogenetic shifts in diet. Further investigation in other species and sites are needed to more fully ascertain the role of selectivity in plastic ingestion in this marine vertebrate group.
... Sheet-like items, represented by plastic bags, wraps and packaging, have also been reported as the most abundant shape of litter ingested by green turtles in other nearshore areas of the western Atlantic (e.g. Bugoni et al., 2001;Tourinho et al., 2010;Guebert-Bartholo et al., 2011;Di Beneditto and Awabdi, 2014;González Carman et al., 2014;da Silva Mendes et al., 2015;Santos et al., 2015;Vélez-Rubio et al., 2018;Rizzi et al., 2019;Petry et al., 2021). Although soft plastic items have been considered the most dangerous because they have a higher probability of causing obstructions (Roman et al., 2020), hard plastic fragments can be sharp and, therefore, damage the GI. ...
... Other studies from the Atlantic reported frequencies of occurrence of marine litter ingestion by green turtles between 70% and 90% (e.g. Santos et al., 2015;Colferai et al., 2017;Vélez-Rubio et al., 2018;Rizzi et al., 2019;Petry et al., 2021). In addition, and in line with previous findings in the region (e.g. ...
Article
Survivorship of early life stages is key for the well-being of sea turtle populations, yet studies on animals that distribute around oceanic areas are very challenging. So far, the information on green turtles (Chelonia mydas) that use the open NE Atlantic as feeding grounds is scarce. Strandings occurring in oceanic archipelagos can provide relevant information about the biology, ecology and current anthropogenic pressures for megafauna inhabiting the open ocean. In this study, we analysed stranding events of green turtles found in the Azores archipelago to investigate interactions with marine litter. In addition, we quantified and characterized litter items stranded on beaches to provide a direct comparison between the ingested items with the debris found in the environment. A total of 21 juvenile green turtles were found stranded in the region between 2000 and 2020 (size range: 12–49 cm, CCL). Overall, 14% of the animals were entangled in marine litter and 86% of the turtles necropsied had ingested plastic. The mean abundance of items ingested was 27.86 ± 23.40 and 98% were white/transparent. Hard plastic fragments between 1 and 25 mm were the most common shape recovered in the turtles, similarly to what was found on the coastline. All of the litter items analysed with pyrolysis GC-MS revealed to be polyethylene (PE). This study provides the first baseline assessment of interactions of plastic litter with juvenile green turtles found at the east edge of the North Atlantic Subtropical Gyre. The combination of these results supports the hypothesis that migratory megafauna that use remote oceanic islands as a feeding ground are exposed to anthropogenic litter contamination dominated by plastics, even when these regions are located far away from big industrial centers or populated cities.
... This high rate of plastic ingestion (88% of prevalence) is similar to those found in past studies performed elsewhere in the coast of Rio Grande do Sul: 60.5% (Bugoni et al., 2001), 100% (Tourinho et al., 2010), 72.6% (Colferai et al., 2017) and 81.3% (Rizzi et al., 2019). High rates of plastic ingestion by green turtles have also been reported in other regions of Brazil and Uruguay, ranging from 70 to 100% of all sampled individuals (Carman et al., 2014;Santos et al., 2015;Vélez-Rubio et al., 2018). ...
... Fragments of plastic bags and plastic sheets, as well as hard and threadlike plastics were predominant in our samples, similar to other studies of sea turtles across the globe (Schuyler et al., 2014a(Schuyler et al., , 2014bClukey et al., 2017;Colferai et al., 2017;Pham et al., 2017;Vélez-Rubio et al., 2018). Threadlike plastics were mainly composed by nylon lines used in fisheries. ...
Article
Five of the seven extant sea turtle species in the world forage on the coast of Southern Brazil at least in some stage of their life cycle. The green turtle Chelonia mydas frequently strands on beaches of Rio Grande do Sul State. The species is currently classified as vulnerable to extinction in the region, and pollution by marine debris is one of the most conspicuous threats to its conservation. In this study, we quantified and characterized plastic ingestion by juvenile green turtles in waters off the southern Brazilian coast between 2013 and 2016. We analysed the gastrointestinal content of 17 beached carcasses and registered debris ingestion in 15 individuals (88%). On average, each green turtle ingested 38.4 ± 88.5 plastic fragments. White and transparent plastic bags and plastic sheets were predominant. Our results indicate a high interaction between juvenile green turtles and marine debris off the coast of Southern Brazil.
... Há também riscos relacionados à pesquisa sísmica marítima, que constitui uma etapa fundamental para a exploração petrolífera. Segundo dados de literatura, essa atividade pode gerar quadros de estresse agudo, com alterações na fisiologia e comportamento das tartarugas (O´Hara e Wilcox, 1990;McCauley et al., 2000;Weir, 2007) (Mrosovsky, 1981;Bjorndal et al., 1994;Mrosovsky et al., 2009;Schuyler et al., 2013), inclusive em todo o Atlântico Sul Ocidental (Bugoni et al., 2001;Mascarenhas et al., 2004;Ivar-do-Sul e Costa, 2007;Tourinho et al., 2010;Santos et al., 2015;Vélez-Rubio et al., 2018). Os plásticos acumulados nos lagos, rios e mares são de dimensões variadas, indo desde materiais visíveis a olho nu até partículas microscópicas. ...
... Quando a categoria OL é considerada em conjunto com as observações externas de indícios de interação com óleo, esse achado soma 11 casos. Cabe destacar, contudo, que tais impactos são de responsabilidade difusa, já que podem ter mais de uma fonte causadora, não podendo ser atribuídos exclusivamente ao setor de óleo e gás.A ingestão de resíduos sólidos de origem antrópica constitui uma importante ameaça às tartarugas marinhas e tem sido relativamente bem documentada em todo o Atlântico Sul Ocidental(Bugoni et al., 2001;Mascarenhas et al., 2004; Ivar-do-Sul e Costa, 2007;Tourinho et al., 2010;Guebert- -Bartholo et al., 2011;Macedo et al., 2011;Stahelin et al., 2012;Awabdi et al., 2013;Carvalho et al., 2015;Gonzalez- -Carman et al., 2015;Mendes et al., 2015;Vélez-Rubio et al., 2018). Milhares de toneladas de lixo, em grande parte constituídas de material plástico, chegam aos oceanos anualmente. ...
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O presente trabalho tem por objetivo reunir informações de avistagem e encalhe de quelônios marinhos gerados no âmbito do Projeto de Caracterização Regional da Bacia de Sergipe-Alagoas (PCR-SEAL, 2013-2015), do Projeto de Avistagem da Biota Marinha e Embarcações de Pesca (Biota, 2014-2015) e do Programa Regional de Monitoramento de Encalhes e Anormalidades na Área de Abrangência da Bacia de Sergipe-Alagoas (PRMEA, 2010-2015), descrevendo sua riqueza, composição, distribuição espacial e sazonal e fatores de ameaça no litoral entre o sul de Alagoas e o norte da Bahia. Foram realizados 4.616 registros, sendo 17 de avistagem e 4.599 de encalhes. Entre os encalhes, 382 foram de tartarugas vivas e 4.217 de mortas. Duas espécies foram registradas através da metodologia de avistagem, Lepidochelys olivacea (n = 7) e Caretta caretta (n = 4), enquanto as cinco espécies foram identificadas pelo PRMEA: Chelonia mydas (n = 2.456), L. olivacea (n = 1.971), Eretmochelys imbricata (n = 87), C. caretta (n = 67) e Dermochelys coriacea (n = 1). A metodologia de avistagem mostrou-se menos eficaz em termos de número de registros e de espécies, mas ainda assim apontou sinais sobre a utilização da região por tais organismos. Os dados de encalhe, por sua vez, foram numericamente mais expressivos e importantes para indicar fatores de ameaças e a interação com atividades humanas. Assim, tais informações se complementam, contribuindo consequentemente para o planejamento de empreendimentos e para a conservação desses recursos biológicos na região.
... Marine debris ingestion and entanglement have caused morbidity and mortality in all seven of sea turtle species (Franzen-Klein et al., 2020). The incidence of plastic ingestion in these post-hatchlings is higher than that reported for later life-stages (Campani et al., 2013;Camedda et al., 2014;Vélez-Rubio et al., 2018). However, the incidence of plastic ingestion varies by year and geographic location (Gramentz, 1988;Witherington, 1994;Tomás et al., 2002;Parker et al., 2005;Boyle and Limpus, 2008;Campani et al., 2013;Camedda et al., 2014;Schuyler Q. et al., 2014a;Pham et al., 2017;Vélez-Rubio et al., 2018;Duncan et al., 2019; Table 1). ...
... The incidence of plastic ingestion in these post-hatchlings is higher than that reported for later life-stages (Campani et al., 2013;Camedda et al., 2014;Vélez-Rubio et al., 2018). However, the incidence of plastic ingestion varies by year and geographic location (Gramentz, 1988;Witherington, 1994;Tomás et al., 2002;Parker et al., 2005;Boyle and Limpus, 2008;Campani et al., 2013;Camedda et al., 2014;Schuyler Q. et al., 2014a;Pham et al., 2017;Vélez-Rubio et al., 2018;Duncan et al., 2019; Table 1). ...
Article
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Pollution from anthropogenic marine debris, particularly buoyant plastics, is ubiquitous across marine ecosystems. Due to the persistent nature of plastics in the environment, their buoyancy characteristics, degradation dynamics, and ability to mimic the behavior of natural prey, there exists significant opportunity for marine organisms to ingest these man-made materials. In this study we examined gastrointestinal (GI) tracts of 42 post-hatchling loggerhead (Caretta caretta) sea turtles stranded in Northeast Florida. Necropsies revealed abundant numbers of plastic fragments ranging from 0.36 to 12.39 mm in size (length), recovered from the GI tracts of 39 of the 42 animals (92.86%), with GI burdens ranging from 0 to 287 fragments with a mass of up to 0.33 g per turtle. Post-hatchlings weighed from 16.0 to 47.59 g yielding a plastic to body weight percentage of up to 1.23%. Several types of plastic fragments were isolated, but hard fragments and sheet plastic were the most common type, while the dominant frequency of fragment color was white. Fragment size and abundance mixed with natural gut contents suggests significant negative health consequences from ingestion in animals at this life stage. Gaining greater insight into the prevalence of plastic ingestion, the types of plastic and the physiological effects of plastic consumption by multiple life-stages of sea turtles will aid the prioritization of mitigation efforts for the growing marine debris problem. This report demonstrates that plastic ingestion is a critical issue for marine turtles from the earliest stages of life.
... Work by Parker el al. 54 from 1990−1992 with juvenile and subadult loggerheads and Mrosovsky et al. 55 Rubio et al. 56 with juvenile and subadult green sea turtles reported higher frequencies of 52 and 70% of animals that ingested plastic particles, respectively, which are typically buoyant in seawater. Any reduction in the efficiency of nutrient acquisition and absorption would be expected to be of the greatest consequence to post-hatchling and juvenile sea turtles with limited body energy reserves to prevent starvation or gut function. ...
Article
From July 2015 to November 2016, 96 post-hatchling sea turtles were collected from 118 km of Atlantic coastline in Florida, USA, including loggerhead, green, and hawksbill sea turtle species. Forty-five of the recovered turtles were rehabilitated and released, but the remaining 52 died and were frozen. At necropsy, the gastrointestinal tracts of most the turtles contained visible plastic, and collected particles of 27 individuals were chemically characterized by Raman microscopy as polyethylene, polypropylene, polyethylene terephthalate, and polystyrene. Mesoparticle plastic fragments 1.0 to 8.7 mm, microparticle fragments 20 to 1000 µm, and nanoparticles 5 to 169 nm were identified in the turtles. Polyethylene and polypropylene were the most common plastics ingested from specimens representing 54.1% and 23.7% of the total observed mesoparticles and 11.7% and 21.0% of the total observed microparticles, respectively. A plastic-to-body mass ratio of 2.07 mg/g was determined for this group. The authors suggest that ingestion of micronizing plastic by post-hatchling sea turtles is likely a substantial risk to survival of these endangered and threatened species. This study also provides some of the first evidence for the formation of nanoscopic plastic particles that we theorize forms in the post-hatchling and juvenile environment and are present post-ingestion.
... SIA has developed in the past two decades as a powerful tool to complement these traditional methods of studying diet and trophic ecology (see review by Haywood et al. 2019). Analysis of the composition of stable isotopes (δ 13 C and δ 15 N) in tissues with different residence times provides historical evidence of diet and patterns of ontogenetic shift Cardona et al. 2009;Vander Zanden et al. 2013;Vélez-Rubio et al. 2018). For example, blood serum represents food consumed recently and epidermal tissue or scutes represent the diet consumed several months previously (Reich et al. 2008). ...
Article
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To better understand dietary requirements, trophic shifts, and trophic interactions of the threatened green turtle (Chelonia mydas), we conducted a comprehensive global review and literature tabulation (177 studies) reporting diets of individuals > 25 cm carapace length. We analysed those studies involving natural sites and healthy animals that reported relative proportions of all diet components (67 studies, 89 datasets at 75 sites, 13 geographic sub-regions, 3 oceans). We compared diets by sub-region and foraging site relative to four diet components, i.e., seagrass, macroalgae, terrestrial plants (including mangroves) and animal matter. To assess sea surface temperature (SST) as an environmental driver, values were extracted from satellite data (single year) and site-specific observations (study durations) and examined relative to diet composition. Satellite data indicated that at warmer sites with temperatures > 25 °C (≥ 6 months annually), diet was predominantly herbivorous (mean = 92.97%; SE = 9.85; n = 69 datasets). At higher latitude sites and in cold-water currents with SST < 20 °C (≥ 6 months annually), dietary animal matter featured prominently (mean = 51.47%; SE = 4.84; n = 20 datasets). Site-specific observations indicated that SST had a small but significant effect on contributions of animal matter (r 2 = 0.17, P = < 0.001) and seagrass (r 2 = 0.24, P = < 0.001) but not macroalgae and terrestrial plants. Our study presents the first quantitative evidence at a global scale that temperature may be an important driver of omnivory, providing a new perspective on variations in green turtle diet, especially in light of global warming and climate change.
... Overall, it is necessary to develop systematic assessments in order to evaluate the impact of marine debris (plastic pollution, ghost nets, among others) in the study area (Guada & Sole 2000). We recognise that marine debris may be impacting marine turtles in other ways that we have yet to observe (Duncan et al. 2017;Caron et al. 2018;Vélez-Rubio et al. 2018). We suggest that it would be highly beneficial to involve all fishing communities connected by the waters of the Gulf of Venezuela in the monitoring of marine debris and its impacts to marine turtles, and to evaluate all potential biological, environmental and social consequences of this threat. ...
Article
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Marine megafauna is impacted by human-generated waste (Grant et al. 2012). Recent evaluations highlight the major threat posed by plastic pollution on the survival of charismatic megafauna, including penguins, aquatic mammals, seabirds, and marine turtles (González Carman et al. 2014; Wedemeyer-Strombel et al. 2015; Pham et al. 2017). Indeed, marine debris appears to affect all marine turtle species in all the habitats they use during their complex life cycle, including migratory routes, seasonal feeding grounds, and overwintering areas (Duncan et al. 2017, In press). The Gulf of Venezuela (GV), located in the southern Caribbean, is considered to be one of the most important feeding grounds for marine turtles in the country (Buitrago et al. 2008; Guada & Sole 2000). However, marine turtles found in the GV are exposed to several anthropogenic threats, primarily: (a) take of immature and adult-sized individuals of at least four species; (b) trade of marine turtle parts or products; (c) habitat degradation due to coastal development, particularly through dredging operations for navigation channel management in the southern portion of the GV; (d) exposure to frequent oil spills (Barrios-Garrido 2018). Moreover, recent studies have revealed an increase in exposure to some threats such as contamination (Barrios-Garrido et al. 2013; Petit-Rodriguez et al. 2013). Here we present further evidence of the threat of marine debris on marine turtle populations along the Venezuelan Guajira Peninsula on the GV. The Venezuelan Guajira Peninsula is located in the Zulia state, in north-western Venezuela, and forms the western side of the Gulf of Venezuela (Fig. 1). It is considered an important feeding area for at least four different species of marine turtles (Barrios-Garrido et al. 2017b). Although its human population is low in numbers (Almanza Vides et al. 2017), the Venezuelan Guajira Peninsula is highly affected by marine pollution (Pulido Petit et al. 2017). It occurs mainly due to constant blowing effect of the trade winds and sea currents along the coastal area (Morán et al. 2014; Gutierrez Leones et al. 2015). As part of regular scientific patrols (in-water and artisanal port surveys) carried out by members of the NGO “Grupo de Trabajo en Tortugas Marinas del Golfo de Venezuela (GTTM-GV)” (Barrios- Garrido & Montiel-Villalobos 2016), 55 stranded marine turtles (Chelonia mydas, Eretmochelys imbricata, Dermochelys coriacea, and Caretta caretta) were found in the study area between January and December 2011. In addition, in June 2016, during a separate survey, we rescued a juvenile green turtle on Zapara Island with evidence of plastic ingestion. In all cases, we collected standardized data from the stranded turtles, including curved carapace length (CCL), and we attempted to determine the cause of stranding. Necropsies were carried out when we encountered dead turtles. Due to logistic challenges in transporting carcasses to Maracaibo city (the state capital), only six turtles were necropsied in the Laboratory of General Ecology, at the University of Zulia; the others were necropsied in the field. From the 55 necropsied turtles, we identified marine debris in three cases (5%) of all 2011 samples. However, in only one turtle was marine debris identified as the cause of death. Note that the three turtles identified with marine debris were from the group of six carcasses necropsied under optimal conditions in the Laboratory of General Ecology in Maracaibo.
... Rismang et al., (2018) explained that prior to conservation, sea turtles were used as raw material to support human social life which led to a decrease in its population. The catalysts for the extinction of turtles are destruction of nesting habitats, coastal abrasion, and turtle food that has been exploited on a large scale (Siqueira-Silva et al., 2020;Vásquez-Carrillo & Peláez-Ossa, 2021;Vélez-Rubio et al., 2018). Kuenzi & McNeely, (2008) continues by discussing ecotourism, namely nature-based tourism, as an option in promoting a unique and authentic environment, as well as being a tourism site. ...
Article
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Sea turtles in Bali has been exploited excessively, which caused decrease in population, and this issue has placed sea turtles threatened to extinction. This review article aimed to provide information regarding the status, trends, and potential of sea turtles in Bali. Information given in this article is vital to ensure reliable knowledge not to only understand our current situation, but also to increase efficiency in reliant to the problem sea turtles face. The literature study method is used to write this review paper, namely by accessing a number of research paper published nationally and internationally. It was explained that the status of sea turtles is known to be endangered and law enforcement is not sufficient overcoming the problem. Conservation trends such as nurturing hatchlings have shown to not only help restore the population of sea turtles, but also to bring economic benefits to the conservation sites and the people. Potentials of ecotourism and DNA Barcoding has shown to be effective to benefit the people economically and increase the efficiency of law enforcement and conservation. Solutions and methods of improvement such as ecotourism and DNA Barcoding explained in this article is practical for Bali to adapt, so that sea turtle conservation is capable to overcome its status and incline to its potential.
... This result can be explained by the fact that the oceanic and sub-adult green turtles are commonly found in shallow-water neritic habitats (Meylan and Meylan 1999) and they are more exposed to anthropogenic threats. A study on the impact of marine debris ingestion in the stranded green turtles found a negative correlation between the presence of marine debris 11.4 0 page 10 of 15 Zoological Studies 57: 53 (2018) and green turtle's size in the Uruguayan waters between (Velez-Rubio et al. 2018). Moreover, Snape et al. (2013) stated that juvenile green turtles are more sensitive to fishing activities than adults regarding the differences in habitat use patterns. ...
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Data on stranded sea turtles allow us to obtain information about age classes, temporal and spatial distributions, and mortality rates in turtles. This study aims to investigate life stages, temporal variation in the number of stranded, body size trend, causes of stranding, and scute deviation of stranded sea turtles on Samandağ Beach, the eastern Mediterranean coast of Turkey during 2002-2017. A total of 302 stranded dead turtles were found. Among these, 167 (55.4%) of them were Chelonia mydas, 127 (42%) Caretta caretta, 2 (0.6%) Trionyx triunguis, and 6 individuals (2%) were unidentified. The mean annual stranding values over the years were 10.5 (ranging from 6 to 22) and 7.9 individuals (ranging from 4 to 21) for C. mydas and C. caretta, respectively. Although the adult green turtles were less stranded, sub-adult and adult stages of the loggerhead turtles were intensively stranded. As the body size of the stranded green turtle has slightly increased, the number of stranded green turtles has decreased over the years. Stranding of loggerhead turtles showed no trend in frequency or body size. The causes of death showed significant differences between the two species as well as among the years. Fishing activities and marine pollution is the main cause of strandings on Samandağ Beach. Oceanic and sub-adult stage individuals were stranded in especially high numbers due to plastic materials. Adult stages in both sea turtle have less carapacial scute deviation. The present study contributes to the stranded data for both sea turtle species in the Mediterranean. Natal origins of the stranded sea turtles on Samandağ Beach should be investigated and a stranding network system should be urgently established.
... Overexploitation is one of the most important threats to the marine environment; fisheries and their continued resource consumption has led to a situation where the 33.1% of world fish stocks are subject to overfishing (Food and Agriculture Organization, 2018), triggering drastic reduction in species population sizes like it happened in the case of the Bluefin tuna (Thunnus thynnus) in the Mediterranean Sea (Block, 2019). Similarly, anthropogenic litter has become another serious problem for marine ecosystems, as debris ends up in the sea where marine life is harmed: some species can get strangled by nets, macroplastics can cause death due to indigestions and microplastics (plastics degraded into particles smaller than 5 mm) can enter the food chain and become sources of toxic chemicals that are released to the environment (Vélez-Rubio et al., 2018;Liu et al., 2019). All along with this, our oceans are facing many other threats that alter the ecosystems, such as climate change that is causing global declines in tropical and subtropical coral species (Hughes et al., 2017) or shippingassociated pollution that causes mortality among many marine species (Walker et al., 2019). ...
Article
Recreational ports are known to be sources of pollution to the coastal marine environment due to the pouring of pollutants or the transfer of invasive species to neighboring areas. Nonetheless, the responsibility of protecting the marine environment does not lie solely on the users of the ports, but also affects the rest of citizens. Thus, an effective communication is necessary between scientists and citizens to avoid the lack of knowledge and boost cooperation against these environmental problems. In this study, (focused on the marina of Gijon, Northwestern Spain) citizens set education and social media as the main sources of information, rarely considering science outreach. Also, their environmental knowledge showed to be based on a visual perception, rather than on a cognitive one, as marine litter was considered a great environmental problem, while invasive species and biofouling went unnoticed, remarking the lack of an effective communication from scientific sources.
... Literature citing debris as a cause of death in sea turtles seldom identified a responsible item, due to both lack of specificity in reporting as well as numerous debris deaths involving a bolus of hard and soft plastic items, commonly reported as "plastic" or "plastic fragments". Sea turtle debris literature qualitatively describes film-like plastics-plastic bags, sheets, and packaging-as trapping hard fragments, with the resulting bolus a reoccuring factor in the reported sea turtle deaths (Colferai, Silva-Filho, Martins, & Bugoni, 2017;Vélez-Rubio et al., 2018). Plastic blockages occur in both the stomach and intestines, with fecal compaction commonly recorded (Colferai et al., 2017;Nelms et al., 2016;Rosolem Lima et al., 2018;Wilcox et al., 2018). ...
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.
... Small juveniles (including post-hatchlings and oceanic juveniles) are hypothesised as the life stage most likely to be highly impacted by plastic pollution as this life stage is particularly vulnerable to entanglement in floating marine plastic debris Duncan et al., 2017), damaging effects of ingestion (Clukey et al., 2017a;Pham et al., 2017;Vélez-Rubio et al., 2018;White et al., 2018;Duncan et al., 2019a;Eastman et al., 2020) and sensitive to potential population-level effects (Rice et al., 2021). The consumption of non-nutritional items can lead to dietary dilution resulting in reduced energy and growth (McCauley and Bjorndal, 1999;Nelms et al., 2016), and has been shown to cause damage and blockage to the gastrointestinal tract, cloaca and bladder in some specimen (Bugoni et al., 2001;Lazar et al., 2011;Ryan et al., 2016;Wilcox et al., 2018). ...
Article
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The ingestion of plastic by marine turtles is now reported for all species. Small juvenile turtles (including post-hatchling and oceanic juveniles) are thought to be most at risk, due to feeding preferences and overlap with areas of high plastic abundance. Their remote and dispersed life stage, however, results in limited access and assessments. Here, stranded and bycaught specimens from Queensland Australia, Pacific Ocean (PO; n = 65; 1993-2019) and Western Australia, Indian Ocean (IO; n = 56; 2015-2019) provide a unique opportunity to assess the extent of plastic (> 1mm) ingestion in five species [green (Chelonia mydas), loggerhead (Caretta caretta), hawksbill (Eretmochelys imbricata), olive ridley (Lepidochelys olivacea), and flatback turtles (Natator depressus)]. In the Pacific Ocean, high incidence of ingestion occurred in green (83%; n = 36), loggerhead (86%; n = 7), flatback (80%; n = 10) and olive ridley turtles (29%; n = 7). There was an overall lower incidence in IO; highest being in the flatback (28%; n = 18), the loggerhead (21%; n = 14) and green (9%; n = 22). No macroplastic debris ingestion was documented for hawksbill turtles in either site although sample sizes were smaller for this species (PO n = 5; IO n = 2). In the Pacific Ocean, the majority of ingested debris was made up of hard fragments (mean of all species 52%; species averages 46-97%), whereas for the Indian Ocean these were filamentous plastics (52%; 43-77%). The most abundant colour for both sites across all species was clear (PO: 36%; IO: 39%), followed by white for PO (36%) then green and blue for IO (16%; 16%). The polymers most commonly ingested by turtles in both oceans were polyethylene (PE; PO-58%; IO-39%) and polypropylene (PP; PO-20.2%; IO-23.5%). We frame the high occurrence of ingested plastic present in this marine turtle life stage as a potential evolutionary trap as they undertake their development in what are now some of the most polluted areas of the global oceans.
... The particular characteristics stated above, in addition to favouring the development of commercial fisheries, make the RLPMF one of the most important and southernmost areas of feeding and development grounds for three endangered sea turtle species, the green turtle (Chelonia mydas), loggerhead turtle (Caretta caretta), and leatherback turtle (Dermochelys coriacea) (López-Mendilaharsu et al., 2009;Fossette et al., 2010;González-Carman et al., 2011;Marcovaldi, Thomé & Fallabrino, 2018). Sea turtles' complex life history and wide distribution range make them highly susceptible to anthropogenic threats such as fisheries interactions and marine pollution throughout their different life stages (Tomás et al., 2002;Gallo et al., 2006;Wallace et al., 2010;Wallace et al., 2013;Lewinson et al., 2014;Nelms et al., 2015;Vélez-Rubio et al., 2018). Fisheries alone are responsible for an estimated annual bycatch of 85,000 sea turtles worldwide in monitored fleets (Wallace et al., 2010). ...
Article
• Fisheries bycatch of non‐target species in the commercial fleet is a major source of anthropogenic injury and mortality for sea turtles and marine megafauna. • The Río de la Plata maritime front (RLPMF) and its adjacent international waters – comprising part of the Argentine and Uruguayan exclusive economic zones, is a highly important fishing ground in the south‐western Atlantic Ocean as well as feeding and development grounds for sea turtles. • This paper analyses the distribution of the bottom and pelagic trawling fishery within the RLPMF using information from Vessel Satellite Monitoring System. With this information, areas of highest trawling intensity were defined and further evaluated their overlap with sea turtle habitat‐use areas from available sea turtle satellite tracking information. • Results besides identifying high‐susceptibility areas for sea turtle bycatch by the commercial trawler fleet along the RLPMF, provide predictive tools to identify vulnerable areas to interaction of sea turtles and the commercial fishing fleet. • Implementation of bycatch mitigation measures, such as reduced fishing effort areas by the Argentine and Uruguayan fisheries management agencies has the potential to benefit the fisheries as well as marine megafauna. Furthermore, there is a need for additional research on the impact that this fleet can have on sea turtles present in the area.
... Sub-lethal effects include dietary dilution or assimilation of contaminants derived from marine litter (Bjorndal, 1997;McCauley and Bjorndal, 1999). In severe cases, debris can block or tear their digestive tracts resulting in the death of the turtles (Bjorndal et al., 1994;Tom as et al., 2002;V elez-Rubio et al., 2018). ...
Article
Anthropogenic marine debris is one of the major worldwide threats to marine ecosystems. The EU Marine Strategy Framework Directive (MSFD) has established a protocol for data collection on marine debris from the gut contents of the loggerhead sea turtle (Caretta caretta), and for determining assessment values of plastics for Good Environmental Status (GES). GES values are calculated as percent turtles having more than average plastic weight per turtle. In the present study, we quantify marine debris ingestion in 155 loggerhead sea turtles collected in the period 1995-2016 in waters of western Mediterranean (North-east Spain). The study aims (1) to update and standardize debris ingestion data available from this area, (2) to analyse this issue over two decades using Zero-altered (hurdle) models and (3) to provide new data to compare the only GES value available (off Italian waters). The composition of marine debris (occurrence and amounts of different categories) was similar to that found in other studies for the western Mediterranean and their amounts seem not to be an important threat to turtle survival in the region. Model results suggest that, in the study area, (a) period of stranding or capture, (b) turtle size and (c) latitude are significant predictors of anthropogenic debris ingestion (occurrence and amount) in turtles. The GES value for late juvenile turtles (CCL>40 cm) has decreased in the last ten years in the study area, and this is very similar to that obtained in Italian waters. We also provide a GES value for early juvenile turtles (CCL≤40 cm) for the first time. Recommendations arising from this study include ensuring use of (1) the standardized protocol proposed by the MSFD for assessing marine debris ingestion by loggerhead sea turtles and (2) the ecology of the turtles (neritic vs oceanic), rather than their size, to obtain GES values.
... Si bien se ha reportado el consumo de carne y la comercialización de caparazones, las amenazas principales se centran en la pesca incidental, deportiva, artesanal e industrial (Lezama et al. 2004;Lezama 2009;Laporta et al. 2006;Figs. 57 y 58) y la ingesta de residuos de origen antrópico (Vélez-Rubio et al. 2018b). Esta última amenazada ha sufrido un gran incremento en los últimos años, siendo que en 2001 un 14% de los individuos analizados presentaba residuos, mientras que en el período 2009-2013 la cifra se sitúa en el 72,2% (Vélez-Rubio et al. 2018b). ...
... Indeed, we estimate that the number of deaths caused by plastic ingestion is higher than deaths for bycatch in Uruguay at present. Our studies revealed that the presence of plastic debris in green turtle digestive tracts increased from 14.5% in the period 2001 to 2003 to 75.5% in the period 2009e2013 [11] and appears to be an ever-growing issue. Furthermore, since plastic hazards are affecting the early life stages of the species in Uruguay, the future viability of the Chelonia mydas subpopulation in the South Atlantic region could be compromised (see regional management units [RMUs] in Ref. [12]). ...
Chapter
Plastic pollution is now considered to be one of the main threats to the marine environment. Plastics are ubiquitous and persistent pollutants that tend to undergo fragmentation and be concentrated in oceanic gyres and coastal fronts by the combined actions of winds and currents. When these garbage patches overlap with key habitats for sea turtles, the consequences for these species are dramatic. Ingestion, bioaccumulation, and entanglement, among others, are frequent impacts of plastic pollution on sea turtles’ health. Since 1999, the local NGO Karumbé has been working tirelessly for the conservation of marine turtles in Uruguay. This chapter discusses the experiences of the Karumbé initiative in the last 20 years.
... So that this decompensation against other groups may be due to the greater amount of fragments against fibers in coastal habitats, secondly, birds select plastic particles that resemble zooplankton prey (Floren and Shugart, 2017), so depending on the similarity of the prey of each species there will be a prevalence towards one type of microplastic or another. This case is also notable in turtles, which have a greater attraction to components similar to gelatinous macro-zooplankton (Vélez-Rubio et al., 2018). Prevalence of pellets in birds with respect to the rest of the groups is due to the fact that the areas where the samples were analyzed are closer to plastic industries that use this type of microplastics in their production processes (Adika et al., 2020), and that they can release them in nearby areas, affecting the local marine fauna. ...
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Plastics are the most important component in marine debris. In turn, within plastics, microplastics (<5 mm) are those that most affect marine biota. Thus, this review has as its main objective to show the current state of studies of microplastics, as well as to determine the groups of vertebrates most affected by microplastics, and the type and predominant color of microplastics. For this research, we review a total of 132 articles, from 2010 to May of 2020. Our results show that the group more affected are turtles with 88% of the specimens contaminated by microplastics and median of 121.73 particles/individue. The predominant type is fibers (67.3%), polymer is polyethylene (27.3%), size is less than 2 mm (73.6%), and color is blue (32.9%).
... Nevertheless, ocean pollution is one of the greatest threats to the marine environment and the organisms that depend on it (Sutherland et al. 2010;Vegter et al. 2014;Gall and Thompson 2015). Plastics are frequently found in the digestive tract of sea turtles, especially Green Turtles, which has been widely documented in the South Atlantic (Bugoni et al. 2001;Tourinho et al. 2010;Jerdy et al. 2017;Vélez-Rubio et al. 2018;Rizzi et al. 2019). Although this threat may have been underrepresented in our study, recent studies suggest that plastic pollution is a significant threat to this mixed foraging aggregation. ...
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Sea turtles are subject to a wide range of human threats. Information collected from sea turtles found dead or debilitated (termed strandings) can provide valuable insights into these threats. In recent years, extensive beach monitoring projects implemented along the entire coast of Brazil (7,367 km) have facilitated data collection on regional sea turtle strandings. Here, we compiled stranding data from the Santos Basin in the state of Rio de Janeiro, Brazil, from 19 September 2016 to 19 September 2019. During this period, we recorded 3,957 sea turtle strandings of which 3,508 were dead turtles. We recorded five turtle species including 3,587 Green Turtles (Chelonia mydas), 242 Loggerhead Turtles (Caretta caretta), 76 Olive Ridley Turtles (Lepidochelys olivacea), 18 Leatherback Turtles (Dermochelys coriacea), eight Hawksbill Turtles (Eretmochelys imbricata), and 26 unidentified individuals. From all species, 12 were oceanic-stage juveniles, 3,663 were neritic-stage juveniles, and 147 were adults. A total of 539 strandings (13.6%) showed signs of anthropogenic interactions: 318 involved fishing gear, 125 involved watercrafts, 90 showed evidence of direct injuries from humans, four involved plastic items, and two involved oil pollution. Our results suggest that fisheries bycatch and watercraft collisions (mainly in bays) are the predominant threats to Green Turtles in the state Rio de Janeiro. It also appears that mortality of Loggerhead, Olive Ridley, and adult Leatherback Turtles is associated with fishing activities in feeding areas or in migratory corridors between feeding and breeding areas.
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Pelagic Pacific sea turtles eat relatively large quantities of plastic (median 5 g in gut). Using Fourier transform infrared spectroscopy, we identified the polymers ingested by 37 olive ridley, 9 green, and 4 loggerhead turtles caught as bycatch in Hawaii- and American Samoa-based longline fisheries. Unidentifiable samples were analyzed using high-temperature size exclusion chromatography with multiple detectors and/or x-ray photoelectron spectroscopy. Regardless of species differences in dive depths and foraging strategies, ingested plastics were primarily low-density, floating polymers (51% low-density polyethylene (LDPE), 26% polypropylene (PP), 10% unknown PE, and 5% high-density PE collectively). Albeit not statistically significant, deeper diving, and deeper captured, olive ridley turtles ate proportionally more plastics expected to sink (3.9 %) than intermediate-diving green (1.2 %) and shallow-diving loggerhead (0.3 %) turtles. Spatial, but no sex, size, year or hook depth differences were observed in polymer composition. LDPE and PP, some of the most produced and least recycled polymers worldwide, account for the largest percentage of plastic eaten by sea turtles in this region. These novel data inform managers about the threat of plastic ingestion to sea turtles and may motivate development of more environmentally-friendly practices for plastic production, use and waste management.
Article
Because of their propensity to ingest debris, sea turtles are excellent bioindicators of the global marine debris problem. This review covers five decades of research on debris ingestion in sea turtles from 131 studies with a novel focus on quantities. Previous reviews have focused solely on presence/absence data. Past reviews have called for standardization and highlight biases in the literature, yet none thoroughly describe improvements needed at the data reporting stage. Consequences of three reporting choices are discussed: not reporting quantities of ingested debris (32% of sea turtle studies reported only frequency of occurrence), excluding animals that did not ingest debris (64%), and not normalizing quantities to animal size (95%). Ingestion quantities, corrected for these factors, allowed a first-ever global meta-analysis on the units of g/kg, revealing that hawksbill and green turtles rank highest among sea turtle species, and that the Central and Northwest Pacific and Southwest Atlantic Oceans are hotspots. Furthermore, this review discovered that monitoring efforts are disproportionate to the magnitude of the problem. Large efforts are focused in the Mediterranean Sea where international policies are hotly discussed versus the Central Pacific that has 5-fold greater debris ingestion quantities but represents only 3 % of the global research effort. Future studies are recommended to report quantities of ingested debris using units described herein and make use of the pilot database provided.
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פסולת ימית נפוצה בכל חלקי הסביבה הימית, משפיעה רבות עליה ועל החיים בה, ומהווה מקור לדאגה עולמית. צבי ים, הנפוצים בכל העולם, משתמשים בבתי גידול מרובים במהלך מחזור חייהם, חשופים למגוון רחב של מפגעים וכמות גבוהה של פסולת. אוכלוסיית צבי הים בים התיכון נמצאת תחת איום, בפרט באגן הלבנט שבו אחוזי התמותה הגבוהים ביותר בים בתיכון. המפגש בין צבי הים לסוגי הפלסטיק השונים מתרחש בכל אזורי המחייה שלהם ולכן נבחרו כביו אינדיקטורים עבור ניטור השפעת הפסולת הימית על בע"ח. הפגיעה מפלסטיק מגוונת, ומתחלקת לשני סוגים עיקריים: הסתבכות ועיכול. הפסולת שגורמת להסתבכות מתחלקת לשתי קטגוריות עיקריות: ציוד דיג (אקטיבי ופסיבי) ופסולת ממקור יבשתי. הפגיעה מציוד דיג יכולה לנבוע מדיג אקטיבי ברשתות דיג ומכמורת, קרסים ומערכי חכות בעודן פעילות במרחב המחייה של הצבים. שחרור הצב שהסתבך ללא טיפול מתאים עלול להוביל בהדרגה גם להסתבכות פסיבית שגורמת לזיהומים, נמקים, לתזונה לקויה, לאבדן גפיים ולמוות. דו"ח זה מציג לראשונה מידע על השפעת פסולת הפלסטיק על צבי ים בישראל ממידע שנאסף במשך 22 שנים במרכז להצלת צבי הים וכן בפיילוט של שנה בניטור פסולת בקיבות צבי הים, שנעשה בשיתוף פעולה של המרכז עם החברה לחקר ימים ואגמים לישראל. ניתוח המידע מצביע על לא פחות ממצב חירום סביבתי. המרכז הארצי להצלת צבי ים אוסף נתונים בנוגע לפגיעות צבים החל משנת 1999 . בעבודה זו מוצגות הרשומו ת ממסד הנתונים בנוגע ל-1,473 צבים שנאספו בשנים 1999-2021 . הרשומות מחולקות על פי מין הצב, פיזיולוגיה )אורך, משקל, זוויג( וסוג הפגיעה. כשליש מהצבים (566 רשומות, חיים או מתים) תועדו כנפגעים ממפגעים הקשורים בפלסטיק. הפגיעותמפסולת פלסטיק מחולקות לשלושה סוגים: פגיעות פלסטיק שונות (n=115) המהוות 21% מסך הפגיעות, פגיעות דיג (n=255) מהוות 47% והפגיעות משקי פוליפרופילן (n=176) המהוות 32% . כחמישית מהצבים המטופלים ( 22% , n=123) לא שרדו . בשנים 2017-2021 נצפתה עליה חדה במספר הצבים הצעירים שנפצעו או מתו בחופי ישראל בגלל הסתבכות (צוואר וגפיים) בשקים ארוגים מפוליפרופילן. דבר זה עלול להשפיע באופן חמור על הגיוס לאוכלוסייה. לכן המרכז להצלת צבים זיהה את השקים כסכנת חיים מרכז ית עבור צבי הים הצעירים, בשלב החיים הפלאגי. שקים אלו משמשים במגוון תעשיות, אך הכתובות עליהם מציינות שייעודם במקור הוא לאריזת מזון של בעלי חיים בחקלאות ונמצאו מספר ספינות שיכולות להיות קשורות למקור השקים בים. ההסתבכויות בשקי פוליפרופילן שכיחות יותר ( 88% מצבי הים חומים, 48% מצבי הים הירוקים) במהלך חודשי הקיץ (יוני-ספטמבר) לאורך כל קו החוף של ישראל . נתיחות לאחר המוות לבדיקת נוכחות פסולת במערכות עיכול בוצעו ב- 2021 במרכז ההצלה ובחקר ימים ואגמים בשני מיני צבי ים: 6 צבי ים ירוקים ו- 15 צבי ים חומים (שנבחרו כמין המייצג באיחוד האירופי). בכל הפרטים נמצאה פסולת במערכת העיכול. בצבי הים הירוקים נמצאה כמות גבוהה בהרבה של פסולת בהשוואה לצבי הים החומים, אך ריכוז הפסולת במערכות העיכול היה גבוה יותר בצב הים החום. ריכוז הפסולת היה גבוה משמעותית בצבים הצעירים בהשוואה לבוגרים, זאת ככל הנראה כתוצאה מאזורי המחייה השונים. חוטי דיג הופיעו ב 8% מקיבות הצבים שנותחו, ייצוג גבוה משמעותית ביחס לתפוצתם בפסולת הצפה או השקופה שנוטרה באזורינו. ניטור הפסולת במערכות עיכול של צבים החל בשנת 2021 ולכן לא נאספו מספיק נתונים על מנת להבין לעומק את הקשר בין סיבת המוות לתכולת הפלסטיק במערכת העיכול. הנתונים המובאים בעבודה זו מייצגים את הנתונים שנאספו במרכז להצלת צבים בלבד וקשה להעריך את אחוז הצבים הפגועים המטופלים במרכז ההצלה מכלל האוכלוסייה. לכן ככל הנראה נתוני הדוח מספקים הערכה בחוסר של כמות הצבים הפגועים והמתים כתוצאה מפסולת ימית. ההשפעה החמורה של הפסולת הימית על צבי הים באזורינו, ובפרט הסתבכות הצבים בפסולת ימית , מחייבת המשך מעקב והבנת התנהגות הצבים והפסולת באזורנו על מנת למזער את הפגיעה העתידית .
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Marine plastics have gained infamy as one of the most pressing environmental issues of our time. Their lightweight and durable properties, and low cost of production have made them an attractive material for packaging and shipping. This production-side preference for cheap plastic products and packaging, coupled with consumption preferences for prepackaged , single-use goods that ultimately overwhelm increasingly costly waste management efforts, has resulted in a persistent, ubiquitous presence of plastic materials globally. Grounded in an extensive review of the literature, this paper reviews the geography of marine plastics research, and the pervasive and persistent effects of plastic on the marine system to aid the discussions of comprehensive mitigation measures. The discussion points raised in this paper highlight the need for a global systems perspective that considers geography, environmental impacts, and sources in order to develop effective mitigation responses to marine litter.
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Read Full Proceedings of 2018 AMTS via: http://www.ausmarineturtlesymposium.com.au/files/01_MT_Symposium_Document_A4_FA_WEB.pdf? -------------------------------------------------------------------------------------------------------------- Global atmospheric temperatures are set to rapidly increase over the next hundred years, consequently altering the microclimates of the sand dune environment where sea turtles lay their eggs. Prior research has demonstrated that high nest temperatures increase embryo mortality, decrease hatchling vigour and size, and feminise the sex-ratio of clutches. Sand temperature is ultimately affected by microclimatic factors of the dunes including sand composition, vegetation cover and sun exposure. Ground vegetation cover is very important for structure in the dune ecosystem and even promotes female nesting behaviour, however its effect on sea turtle clutches in terms of hatching and emergence success and quality of hatchlings has not been quantified. I conducted a study on the loggerhead turtle nests at Mon Repos Conservation Park in southeast Queensland, to investigate the effect of nest location on the incubation success, hatchling morphology and locomotor performance of hatchlings. Twenty-four nests were relocated into a two-factor design, with shade/sun and surface vegetated/cleared as primary factors. Nests in sun had significantly higher nest temperatures and shorter incubation periods than those in the shade, however presence/absence of surface vegetation had no effect on nest temperature. De-vegetated nests had higher emergence success than vegetated nests, with the greatest difference in emergence success occurring between vegetated nests and de-vegetated nests in the shade. Hatchlings that emerged from cooler, shaded nests were larger in carapace size and had better locomotor performance than the more lethargic hatchlings that emerged from sun-exposed nests. To improve the hatchling production and quality of endangered marine turtles at naturally ‘hot’ beaches such as Mon Repos, active management strategies are required. Removing the more problematic and widespread grass species as well as increasing the amount of natural shading over the dunes by mindful planning can be implemented as an adaptable, global strategy to ensure the longevity of all threatened sea turtle populations against the adverse effects of global warming.
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Growing evidence suggests that anthropogenic litter, particularly plastic, represents a highly pervasive and persistent threat to global marine ecosystems. Multinational research is progressing to characterise its sources, distribution and abundance so that interventions aimed at reducing future inputs and clearing extant litter can be developed. Citizen science projects, whereby members of the public gather information, offer a low-cost method of collecting large volumes of data with considerable temporal and spatial coverage. Furthermore, such projects raise awareness of environmental issues and can lead to positive changes in behaviours and attitudes. We present data collected over a decade (2005–2014 inclusive) by Marine Conservation Society (MCS) volunteers during beach litter surveys carried along the British coastline, with the aim of increasing knowledge on the composition, spatial distribution and temporal trends of coastal debris. Unlike many citizen science projects, the MCS beach litter survey programme gathers information on the number of volunteers, duration of surveys and distances covered. This comprehensive information provides an opportunity to standardise data for variation in sampling effort among surveys, enhancing the value of outputs and robustness of findings. We found that plastic is the main constituent of anthropogenic litter on British beaches and the majority of traceable items originate from land-based sources, such as public littering. We identify the coast of the Western English Channel and Celtic Sea as experiencing the highest relative litter levels. Increasing trends over the 10-year time period were detected for a number of individual item categories, yet no statistically significant change in total (effort-corrected) litter was detected. We discuss the limitations of the dataset and make recommendations for future work. The study demonstrates the value of citizen science data in providing insights that would otherwise not be possible due to logistical and financial constraints of running government-funded sampling programmes on such large scales.
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Feeding ecology of juvenile green turtles (Chelonia mydas) was studied from 2008 to 2011 at Samborombón Bay (35°30′–36°30′S, Argentina), combining data on digestive tract examination and stable isotope analysis through a Bayesian mixing model. We found that animal matter, in particular gelatinous plankton, was consumed in large proportions compared to herbivorous food items such as terrestrial plants and macroalgae. This diet is facilitated by the high abundance of gelatinous plankton in the region, thus confirming the adaptive foraging behaviour of the juveniles according to prey abundance in the SW Atlantic. To our knowledge, this is the first study to employ this combination of techniques and to conclusively demonstrate that animal matter, in particular gelatinous plankton, is important in the diet of the neritic green sea turtles.
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We present the first study conducted in a wide spatio-temporal scale on marine turtles strandings (N = 1,107) over a 12-year period (1999–2010) in Uru-guay. Five species were recorded Chelonia mydas (N = 643; 58.1 %), Caretta caretta (N = 329; 29.7 %), Dermochelys coriacea (N = 131; 11.8 %), Eretmochelys imbricata (N = 3; 0.3 %), and Lepidochelys olivacea (N = 1; 0.1 %). The first three species stranded throughout the Uruguayan coast, but differences in distribution pat-terns were detected among species. Although occurring year round, stranding records show a clear seasonal pattern with variation in monthly distribution among species, but with a peak of records in austral summer. Strandings pro-vide indirect evidence of threats to marine turtles in Uru-guayan and surrounding waters, particularly fisheries and marine debris. Our results demonstrate that Uruguayan coastal waters likely serve as a foraging or development area for at least three endangered marine turtle species in temperate waters.
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The green turtle (Chelonia mydas) is a subcosmopolitan species found in tropical and temperate latitudes. The best knowledge on its behavior described an abrupt and irreversible ontogenetic shift that takes place early in life in some areas such as the Greater Caribbean and Australia. Young turtles move from oceanic to neritic habitats, from pelagic to benthic feeding and from an omnivorous to an herbivorous diet. However, whether this pattern applies elsewhere in the range of the species is not known. In the temperate waters of the South West (SW) Atlantic, preliminary evidence suggests that these juveniles would not comply with the tenets of an abrupt and irreversible ontogenetic shift as in tropical waters. We satellite tracked 9 neritic juveniles moving along the coast of Argentina, and applied a switching state-space model combined with kernel density estimation to identify preferential putative foraging areas and migratory routes. Results indicate that immature green turtles are not strictly herbivores or neritic in the temperate SW Atlantic. In summer and fall, juveniles foraged most of the time in estuarine areas without submerged macrophytes. In winter and spring, the turtles migrated north to warm coastal areas where macroalgae and seagrass are available. Concomitant to pelagic feeding, some turtles reached deep water areas where macrophytes are unlikely to occur. Adaptation to local conditions explains behavior better for the SW Atlantic than the abrupt and irreversible ontogenic shift described for warmer waters.
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We present a detailed analysis of sea turtle strandings (n = 619) over a 14 yr period (1993 to 2006) from the Valencian Community (eastern Spain). Loggerhead turtles Caretta caretta accounted for 98.1 % of recorded strandings. Although we detected an increasing trend in the annual number of strandings over the study period, we expect that this Was driven primarily by the increase in detection effort. Loggerhead turtles were mainly juveniles (mean ± SD curved carapace length from notch to tip [CCL] = 53.6 ± 12.6; range: 16 to 80.2 cm, n = 312) and strandings were far more frequent in summer months (69.6 % June to September). We believe that interaction with longline fisheries was by far the main cause of observed stranding (> 28 % of all cases, 43.5 % of 393 turtles with likely mortality cause identified). Turtles showing signs of interaction with longlines were, on average, larger (CCL = 57.5 ± 10.4; range: 29.8 to 80.2 cm, n = 116) than turtles stranded due to other causes (CCL = 51.4 ± 13.3; range: 16 to 79 cm, n = 196; t-test: t = -4.49, p < 0.001) and were more frequent in summer months, when longline fishing effort off the coast was highest. Recent reductions in longline effort may have led to a decrease in recent years in the proportion of stranded turtles with evidence of longline interaction. Although inferences from stranding data must be subject to a number of caveats, when considered over wide spatio-temporal extents and in conjunction with other data sources, they can offer useful insights into the geographic ranges, seasonal distribution and life history of marine species of conservation concern.
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We studied the diet of green sea turtles (Chelonia mydas) at Bahía de los Angeles in the Gulf of California, México. From 1995–1999, we collected esophageal lavage and fecal samples from live-captured turtles and analyzed stomach contents from stranded carcasses encountered in the study area. Foods ingested did not vary with carapace length. Turtles consumed diverse marine algae, with the filamentous red alga Gracilariopsis lemaneiformis the most abundant; other common genera included Gracilaria, Codium, Ulva, and Chaetomorpha. Turtles also augmented their diet with animal matter; 25 nonalga food items were identified, including sponges, tube worms, sea pens, and sea hares. Substratum and anthropogenic debris such as plastic bags and nylon cord were commonly recovered in diet samples.
Chapter
The closest interaction of an organism with its environment is the ingestion of a subset of that environment and the subsequent alteration and absorption of that subset as it passes through the digestive tract of the organism. The absorbed nutrients fuel the productivity — both growth and reproduction — of the organism. The pivotal 200role that nutrition plays in the productivity of individuals and populations — and thus to the conservation of species — has often been overlooked.
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Marine microscopic plastic (microplastic) debris is a modern societal issue, illustrating the challenge of balancing the convenience of plastic in daily life with the prospect of causing ecological harm by careless disposal. Here we develop the concept of microplastic as a complex, dynamic mixture of polymers and additives, to which organic material and contaminants can successively bind to form an ‘ecocorona’, increasing the density and surface charge of particles and changing their bioavailability and toxicity. Chronic exposure to microplastic is rarely lethal, but can adversely affect individual animals, reducing feeding and depleting energy stores, with knock-on effects for fecundity and growth. We explore the extent to which ecological processes could be impacted, including altered behaviours, bioturbation and impacts on carbon flux to the deep ocean. We discuss how microplastic compares with other anthropogenic pollutants in terms of ecological risk, and consider the role of science and society in tackling this global issue in the future.
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The growth of human population and deficient pollution control measures pose significant challenge to the environment. Despite conservation efforts, all sea turtle species are at some risk of extinction. The present study investigated the effect of marine debris on the gastrointestinal tract of green turtles in southeastern Brazil. Of the 777 animals evaluated, 290 showed marine debris in one segment of the gastrointestinal tract. The presence of these materials in the gastrointestinal tract may be harmful, independent of the segment involved, and increases the risk of impaction. Marine debris has become a significant hazard to Chelonia mydas in the region surveyed, causing perforation, rupture, or fecal impaction that, when not treated, is potentially fatal, exposing the intestine to bacterial infection.
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Beaches are social-ecological systems that provide several services improving human well-being. However, as one of the major coastal interfaces they are subject to plastic pollution, one of the most significant global environmental threats at present. For the first time for Uruguayan beaches, this study assessed and quantified the accumulation of plastic and microplastic debris on sandy beaches of the major touristic destination Punta del Este during the austral spring of 2013. Aiming to provide valuable information for decision-making, we performed a detailed analysis of plastic debris, their eventual transport pathways to the coast (from land and sea), and the associated persistent pollutants. The results indicated that the smallest size fractions (<20 mm) were the dominant size range, with fragments and resin pellets as types with the highest number of items. PAHs and PCBs were found in plastic debris, and their levels did not differ from baseline values reported for similar locations. The abundance of plastic debris was significantly and positively correlated with both the presence of possible land-based sources (e.g. storm-water drains, beach bars, beach access, car parking, and roads), and dissipative beach conditions. The analysis of coastal currents suggested some potential deposition areas along Punta del Este, and particularly for resin pellets, although modeling was not conclusive. From a local management point of view, the development and use of indices that allow predicting trends in the accumulation of plastic debris would be critically useful. The time dimension (e.g. seasonal) should also be considered for this threat, being crucial for locations such as Uruguay, where the use of beaches increases significantly during the summer. This first diagnosis aims to generate scientific baseline, necessary for improved management of plastic litter on beaches and their watersheds.
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Marine Protected Areas are increasingly considered in coastal areas as an instrument to preserve threatened fauna and fragile habitats from the detrimental effects of human activities. For this reason baseline data are of utmost importance for the evaluation of the outcomes of ongoing conservation efforts. Along the Uruguayan coast, the area of Cerro Verde (declared protected since 2011) represents the most important foraging and development area for green turtles (Chelonia mydas). Between 2002 and 2009, a long-term capture-mark-recapture programme for green turtles was developed to gather data on demography, ecology and status of the species in the area. Turtles captured were juveniles ranging from 28.8 to 64.3 cm in length over the curve of the carapace (n=514), and results indicated a size-based habitat segregation. Tumour prevalence was 5.3% (n = 27) and was positively correlated with carapace length. The mean body condition index was 1.25 ± 0.14 (n = 494). From the total number of tagged turtles 10.6% were recaptured during the study period. Green turtles showed high site fidelity; 81% of the turtles were recaptured within the same season and 76% were recaptured in different seasons but were found at the original capture spot. Mean annual growth rate was 1.6 ± 0.9 cm year−1. The catch per unit effort of 2008 differed from 2009, higher in 2009, but also significantly different between capture spots. The present study constitutes a baseline dataset for future monitoring of green turtles in the area and provides valuable information for wider analyses of population dynamics in the Southwestern Atlantic Ocean.
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Chelonia mydas is distributed in several regions of the world and they are common in coastal regions and around islands. Between August 2008 and July 2009, 20 specimens of C. mydas were found dead on the beaches of Ubatuba, São Paulo, Brazil. The stomachs were removed and anthropogenic wastes were separated according their malleability and color. Of those animals, nine had ingested marine debris. Soft plastic was the most frequent among the samples and the majority of fragments was white or colorless and was between zero and five cm. Many studies have shown a high incidence of eating waste for some species of sea turtles. The record of ingestion of mostly transparent and white anthropogenic wastes in this study strengthens the hypothesis that these animals mistake them for jellyfish. Although the intake of anthropogenic waste causes impact on the lives of sea turtles, such studies are still scarce in Brazil.
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Marine debris is listed among the major perceived threats to biodiversity, and is cause for particular concern due to its abundance, durability and persistence in the marine environment. An extensive literature search reviewed the current state of knowledge on the effects of marine debris on marine organisms. 340 original publications reported encounters between organisms and marine debris and 693 species. Plastic debris accounted for 92% of encounters between debris and individuals. Numerous direct and indirect consequences were recorded, with the potential for sublethal effects of ingestion an area of considerable uncertainty and concern. Comparison to the IUCN Red List highlighted that at least 17% of species affected by entanglement and ingestion were listed as threatened or near threatened. Hence where marine debris combines with other anthropogenic stressors it may affect populations, trophic interactions and assemblages. Copyright © 2015 Elsevier Ltd. All rights reserved.