Interdecadal variations of the mercury content in Scomber colias in Canary Islands.

Mercury is a very dangerous toxic metal that bioaccumulates very easily in organisms, and it migrates through the food web. The specimens studied in this study were Scomber colias. In the results obtained for the years 1973, 1992, and 2021, the concentration of mercury has been decreasing considerably over the decades, starting with 0.23 ± 0.04 mg/kg in 1973, and having less than half in 2021 with 0.11 ± 0.01 mg/kg. This may be due to the laws imposed by the countries against pollution and to a greater extent in the elimination of mercury; thanks to these measures it has been possible to reduce the concentration of mercury by half in S. colias. Otherwise, the conservation and availability of historical collections of living beings should be considered an unvalued source of information which could help to monitor legislation measures launched to ameliorate the human impact on the natural environment.

The influence of the degassing phase of the Tagoro submarine volcano (Canary Islands) on the metal content of three species of cephalopods.

Underwater volcanic eruptions are a type of natural contamination that affect all marine organisms at a local level. These eruptions usually begin and end a degassing stage of the volcano that, although they do not affect the magnitude of magma emanation, affect organisms to a lesser degree locally, such as cephalopods that due to their metabolism and trophic level, are good bioindicators of contamination. A total of 180 samples of three species of cephalopods were collected for the study: sixty Sepia officinalis, sixty Octopus vulgaris and sixty Loligo vulgaris in the area of the submarine volcano in El Hierro, Tenerife and Lanzarote in the Canary Islands (twenty samples per species in each location), and the metal concentrations (Al, Cd, Cr, Cu, Fe, Li, Ni, Pb and Zn) in each of the samples were analyzed. All species showed significant differences for all metals in El Hierro compared to Tenerife and Lanzarote. All the analyzed species from El Hierro had higher concentrations of the nine studied metals, this is due to the fact that they were caught near the Tagoro submarine volcano, which at the time was in a state of degassing and discharged many metal-rich compounds.

Limpets as bioindicators of element pollution in the coasts of Tenerife (Canary Islands).

Currently, there is an increase in marine pollution around the world; the most affected areas are the coastal ones since on the coast is where anthropogenic pollution first acts. Therefore, it is important to have natural bioindicators as organisms that indicate us in the first instance of this pollution. The main objective of the present research is to determine if Patella aspera and Patella candei crenata show statistical differences in their element content in contaminated areas of the Island of Tenerife and to verify if limpets can be good bioindicators of marine pollution by trace elements and non-essential elements. A total of 160 limpets were taken from 4 slopes of the Island of Tenerife in the Canary Islands. The samples were analyzed using the ICP-OES to obtain results of essential trace elements (Cr, Cu, Fe, Li, Ni, and Zn) and non-essential elements (Al, B, Cd, Pb, and V). P. aspera showed a higher concentration of elements than P. candei crenata, and it was in the Buenavista locality where alarming values of Cd 0.658 ± 0.124 mg/kg were observed for P. aspera. These two limpet species have been found to be useful as bioindicators of marine pollution based on the concentrations of metals especially for Cd and Cu.

Assessments of metallic contents in rare cephalopods from the Canary Islands: relationships with depth habitat and body size.

This study investigated 20 elements in the muscle of 11 cephalopod species caught in the Canary Islands inhabiting from coastal to meso-bathypelagic habitats. Among them, trace element contents from large and elusive cephalopods such as Architeuthis dux, Taningia danae, Lepidoteuthis grimaldii, and Haliphron atlanticus were determined. Statistically significant differences in element concentration were found among class sizes and habitat. Large species that are inhabiting in deepest waters such as Loligo forbesii, A. dux, T. danae, H. atlanticus, and L. grimaldii showed a high load and variability in Fe and Al, while coastal species were characterized by a homogeneous element composition, being the Zn loads highest than other elements. Metal contents in large and elusive cephalopod species were dominated by Fe, Ni, Al, Zn, and Sr, with these species being able to carry important amounts of these elements to predators such as deep-diving odontocetes that reside around the Canary waters.

Characterization of classes of mollusks in the East Atlantic according to their element content.

One hundred and ninety-two samples from six species of mollusks classified into the following taxonomic classes: Gastropoda (Patella aspera, Patella candei crenata), Bivalvia (Mytilus galloprovincialis, Ensis directus), and Cephalopoda (Abraliposis morisii, Pyroteuthis margatifera) were investigated. Samples were collected in the Atlantic Ocean (Canary Islands and Galicia). The concentrations of Al, B, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Mo, Na, Ni, Pb, Sr, V, and Zn were determined by ICP-OES. Statistical analysis verified that the classes of benthic organisms had the highest concentration of elements. However, the Cephalopoda class had the highest Cd (1.685 ± 0.929 mg/kg) and Pb (0.826 ± 1.104 mg/kg) content. On the other hand, the values obtained in this study were compared with studies conducted in other parts of the world to verify the environmental state of the Atlantic Ocean using the organisms studied as bioindicators.

Influence of Biometric and Seasonal Parameters on the Metal Content of Scomber colias in Northwestern African Waters.

Studies of the content of heavy metals and trace elements in fish and other marine organisms are of great importance to know the state of the marine ecosystem. This study has been carried out in northwestern African waters, Scomber colias being the target species, sampling a total of 345 specimens over 2 years. For the determination of metals and trace elements (Al, B, Cd, Cr, Cu, Fe, Li, Ni, Pb, V, and Zn) in the muscle, the ICP-OES (inductively coupled plasma optical emission spectrometry) was used. In the statistical study, the factors (oceanographic and maturity in the seasons, size of the specimens) were used. The samples sampled in the cold season that had high concentrations of metals may be due to the influence that African upwelling has on the Canary Islands. The metallic contents of our samples are lower than those found in the studies in Mauritania and Morocco due to the greater influence that upwelling has in these areas.

Metal content in stranded pelagic vs deep-diving cetaceans in the Canary Islands.

The Canary Islands are home to many cetacean species, many of which are resident species. The present work aims to analyze, for the first time to the best of the authors' knowledge, the macronutrients, micronutrients and trace elements and toxic heavy metals in muscle and liver tissue of six species of stranded cetaceans in the Canary Islands. The study species were: Tursiops truncatus, Stenella frontalis, Delphinus delphis, Grampus griseus, Globicephala macrorynchus and Physeter macrocephalus. Statistical analysis studied the significant differences between the concentrations in muscle and liver tissues, with the differences in element content depending on the type of diving and length of the species. The results indicate that there are differences between muscle and liver for Ca, Cd, Co, Cu, K, Mg, Mn, Mo, Ni, Pb, Sr, V and Zn. Deep-diving animals differ in their concentrations of Cr, Cu, Mg, Mn, Mo, and Zn with respect to shallow-diving animals in muscle and in liver in Al, B, Cr, K, Mn and Mo. As for the differences between sex, the males present differences in their concentrations of B, Cd, K and Mg in muscle tissue with respect to the females, while differences in the liver were only detected in the Fe content. The study of the correlations shows that as the size of the animal increases, the concentration of Cd increases while the concentrations of Al, Cu and Zn decrease. The specimens foraging in shallower waters had the highest concentration of the macronutrient.

Accumulation of toxic metals (Pb and Cd) in the sea urchin Diadema aff. antillarum Philippi, 1845, in an oceanic island (Tenerife, Canary Islands).

This document shows the results obtained from a study on the concentration of toxic heavy metals in the internal tissue and exoskeleton of sea urchins, collected from their natural habitat. The levels of lead and cadmium were measured by Graphite Furnace Atomic Absorption Spectrometry. The mean concentrations of lead and cadmium in the internal tissue were 304.04 and 260.54 microg/kg respectively, whereas in the shell they were 185.02 and 142.48 microg/kg. We also performed a statistical analysis of the differences in the distribution of metals between their exoskeleton and their internal content, a correlation study of the metal content in internal tissue and shell and sampling areas, and a correlation study between the metal content and sample size. Since the sea urchin Diadema antillarum presents a wide range of variation in metal content, this study suggests that this species is an excellent bioindicator of heavy metal contamination.

Heavy and trace metal concentrations in three rockpool shrimp species (Palaemon elegans, Palaemon adspersus and Palaemon serratus) from Tenerife (Canary Islands).

Trace metal concentrations (Fe, Cu, Co, Zn, Ni and V) were investigated in three rockpool shrimp species (Palaemon elegans, Palaemon adspersus and Palaemon serratus) from six littoral sampling sites (polluted and non-polluted) of Tenerife in the Canary Islands (Central Eastern Atlantic), Spain. Sex ratio for all three species has been determined: females predominate over males in all species and significant differences in total length and cephalothorax length was detected between sexes, being females larger than males. By other side, concentrations of trace metals were determined in whole specimens. Higher mean values for every metal were observed in P. adspersus. In males, higher values were observed in P. elegans and P. serratus, whereas in P. adspersus, mean values are higher in females. Finally, mean concentrations of trace metals studied were higher, in general terms, in the two clearly polluted stations: Santa Cruz of Tenerife commercial harbour and its fishery dock dependency.

Determination of metals in Anemonia sulcata (Pennant, 1777) as a pollution bioindicator.

Contamination from metals as a result of anthropic action in coastal marine areas is increasing and it is therefore of great importance to have an appropriate follow-up program in these areas. Samples were taken in the intertidal in 6 sites, of which 5 were in the island of Tenerife and one in the island of Lanzarote (Canary Islands, Spain); in all sites, 15 anemone samples were collected. Twenty metals were analyzed by ICP-OES. The results show the highest concentrations of contamination in the area of Los Silos and Puerto del Carmen for the anthropogenic metals Cr, B, Ni, Cu, Pb, Cd, Fe, Li, and V; Los Silos shows Pb 25.264 ± 27.185 mg/kg and Cd 0.058 ± 0.050 mg/kg, which are high compared with the other sites and indicate that the area may be exposed to a high degree of contamination. Compared with other studies, Los Silos has the same or greater concentrations of anthropogenic metals than areas of greater pollution, such as the Mediterranean Sea or the Indian Ocean. For these reasons, Anemonia sulcata can be used as a bioindicator of anthropogenic contamination and it has become a useful organism for environmental pollution monitoring studies.

Development stage and season influence in the metal content of small pelagic fish in the North-West Africa.

Marine organisms are exposed to great changes caused by man due to discharges into the oceans, so the study of marine pollution is of great value for each ecosystem. For this study, 963 specimens of pelagic fish have been collected, of which 345 are Scomber colias, 294 are Trachurus picturatus and 324 are Sardina pilchardus, it was wanted to study the development and ontogeny in the three species observing if there were variations in their metallic content. The study covered a total of 2 years, from June 2016 to May 2018.16 samples of each species were studied each month, during the 2 years of sampling, from the samplings carried out by the Canary Islands Oceanographic Center of the Spanish Institute Oceanography (COC-IEO) in the markets of the Island of Tenerife. The concentration of 11 anthropic metals was determined in each sample using the Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) technique. Statistical studies were carried out with factors such as the oceanographic season, and the level of maturity of the gonads. S. colias was the species that presented the highest concentration in a greater number of metals. S. pilchardus presents higher concentration in Cu, Li and Zn, in the warm season. These are metals of a very anthropic character on coasts; This species tends to get closer to the coasts compared to the other two and is the cause of its higher concentration in these metals due to the influence of pollution linked to the coast. The immature specimens of the three species had a higher concentration in more metals than the mature specimens.

Ontogenic and seasonal variations of metal content in a small pelagic fish (Trachurus picturatus) in northwestern African waters.

Marine organisms are exposed to great changes induced by human beings due, among others, to discharges into the oceans, increasing marine pollution. For this study, 294 specimens of Trachurus picturatus from the Canary Islands were analyzed during a period of 2 years. The concentration of 11 anthropic metals and trace elements was determined in each individual using the Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) technique. Statistical analyses were carried out considering the following factors: oceanographic season, maturity of the gonads, size of the specimens, season. Immature specimens had higher concentration in more metals than the mature specimens. This fact may be due to the fact that these specimens require a much higher metabolic rate due to their growth and do not detoxify like mature specimens.

Seasonal and ontogenic variations of metal content in the European pilchard (Sardina pilchardus) in northwestern African waters.

Marine fishes are exposed to great human-induced alterations due to the indiscriminate discharges into the sea, increasing marine pollution. For this study, 324 specimens of Sardina pilchardus from the Canary Islands were analized during a period of 2 years (June 2016 to May 2018). The concentration of 11 metals and trace elements (Al, B, Cd, Cr, Cu, Fe, Li, Ni, Pb, V and Zn) was determined in each individual using the Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) technique. Statistical analyses were carried out considering the following factors: oceanographic season, maturity of the gonads in the seasons, size of the specimens. Sardina pilchardus specimens captured in the hot season presented higher Ni, Li and Pb levels than the specimens caught in the cold season. Immature specimens had higher concentration in more metals than the mature specimens. This fact may be due to the fact that these specimens require a much higher metabolic rate due to their growth and do not detoxify like mature specimens. Significant differences were found in the concentration of metals in all the analyzes performed.

Content of lead and cadmium in barred hogfish, Bodianus scrofa, island grouper, Mycteroperca fusca, and Portuguese dogfish, Centroscymnus coelolepis, from Canary Islands, Spain.

Concentration of lead and cadmium has been analyzed in Bodianus scrofa and Mycteroperca fusca captured in the Canary Islands coast. Concentration of Pb ranged from 2.53 to 306.40 and 4.97 to 792.00 microg kg(-1) respectively, while that of Cd ranged from 1.75 to 1854.50 and 6.78 to 656.00 microg kg(-1). The same metals have been analyzed in muscles, liver and skin of Centroscymnus coelolepis from Canary Islands, with contents of Pb and Cd ranged between 24.18-96.12 microg kg(-1) and 32.00-3266.58 microg kg(-1) respectively, and in the Azores Archipelago, with concentrations of Pb and Cd ranged as follow: 18.41-38.99 microg kg(-1) and 5.23-4179.87 microg kg(-1) respectively. Percentage of contribution of both metals to the PTWIs, has also been calculated for both fishes.

Metal content in Mullus surmuletus in the Canary Islands (North-West African Atlantic).

The contents of 3 heavy metals (Al, Cd, and Pb) and 10 trace elements (B, Cr, Cu, Fe, Li, Mg, Ni, Sr, V, Zn) were determined by means of atomic emission spectrometry with inductively coupled plasma (ICP-OES) in 117 specimens of red mullet, Mullus surmuletus. The specimens were taken in two of the Canary Islands; two locations on the island of Tenerife: Candelaria on the northeast coast and Punta de Hidalgo on the north coast and Arguineguín, on the south coast of the island of Gran Canaria. No significant differences were found between the two sites in Tenerife regarding the metal content of the specimens studied, but differences were found between the specimens captured in Arguineguín and the two sites in Tenerife, the latter having higher concentrations of the analyzed metals.

Inferring trophic groups of fish in the central-east Atlantic from eco-toxicological characterization.

The marine organisms are exposed to great human-induced alterations due to the indiscriminate discharges into the sea, which is why the study of marine pollution is of great value for each ecosystem. Each organism bioaccumulates distantly the heavy metals and trace elements in its organism. Because of this it is possible to classify different groups of fish according to their feeding with the content of these metals. Ten fish species were grouped considering their trophic level and habitat ecology (benthic predators, herbivores, omnivores, pelagic predators and superpredator) and analyzed for its metal content. Statistically significant differences were found among all the fish groups, with the Superpredator group containing the highest concentrations in all metals, mainly Fe (103.751 ±â€¯92.151 mg/kg) and Al (28.908 ±â€¯21.221 mg/kg). Therefore, this study highlights that the selection of the species taking into account feeding and habitat partitioning must be carefully considered being crucial to identify fish groups as biological indicators of marine pollution.

Mercury, cadmium, and lead content in demersal sharks from the Macaronesian islands.

The overexploitation of shark and ray fishing as well as anthropogenic pollution in the sea has led to a large decline in their population, and because sharks occupy a high trophic position in the ecosystem, they could have high concentrations of heavy metals such as Hg, Pb, and Cd. This study is based on seven species of demersal sharks which were caught in the Macaronesian archipelagos (Tenerife, Gran Canaria, and the Azores Archipelago). Hg and Pb concentrations were found in the present study to be below those reported in other comparative studies, with the highest reported values of Hg and Pb being 281,738 µg/kg for Pb in Deania profundorum (Smith & Radcliffe, 1912) and 264,30 µg/kg for Hg in Centrophorus uyato, Rafinesque, 1810. As for Cd, the values found here are higher than those in the literature, the highest reported concentration being 120.36 µg/kg in Centrophorus squamosus (Bonnaterre, 1788).

Metals in Mytillus galloprovincialis (Lamarck 1819) and Ensis directus (Conrad 1883): Risk Assessment.

The study has been conducted with inductively coupled plasma optical emission spectrometry to determine the content of toxic heavy metals, macroelements, and essential elements in two species of bivalves of commercial interest in the Canary Islands: the Mediterranean mussel ( Mytillus galloprovincialis, Lamarck 1819) and the razor clam ( Ensis directus, Conrad 1883). The study included 40 samples corresponding to 20 specimens of each species acquired from fishmongers on the island of Tenerife. E. directus had higher levels of metals, except for B, Cd, Na, and Zn (0.98, 0.02, 2,006.93, and 15.07 mg/kg, respectively) compared with those in M. galloprovincialis, B, Cd, Na, and Zn (2.67, 0.12, 2,267.7, and 22.27 mg/kg, respectively). In both bivalve molluscs, the maximum limits established by European legislation on food for human consumption were not exceeded. Likewise, the estimated daily intakes for the toxic metals Pb and Cd were below the admissible daily intakes.

Influence of the submarine volcanic eruption off El Hierro (Canary Islands) on the mesopelagic cephalopod's metal content.

This work investigates whether a submarine volcanic eruption off El Hierro (Canary Islands) in October 2011 influenced the metal contents of two deep water cephalopod species: Abraliopsis morisii and Pyroteuthis margaritifera. This was assessed by comparing metal contents in specimens collected off the island of El Hierro and in the neighbouring islands of La Palma and Tenerife during an experimental deep water fishing trip. The concentration of 20 heavy metals was analyzed in 180 specimens of A. morisii and P. margaritifera collected around the three islands to test for inter-island differences for each species and metal. While both species showed geographical differences in metal concentrations, the main finding was that A. morisii could be a bioindicator species for metals such as Li, Sr and Ca.

Metals in Diplodus sargus cadenati and Sparisoma cretense-a risk assessment for consumers.

The increases in urbanization, demography and industrial activity, along with growing human needs which exploit the resources of the planet, have exponentially exacerbated pollution. In particular, the discharge of heavy metals into the marine ecosystem is a problem of global magnitude, as this may damage the diversity of marine species and ecosystems because of their toxicity, long persistence and bioaccumulation. Consequently, it is necessary to carry out an assessment of the risk of human exposure from the consumption of marine species potentially exposed to this type of pollutants. In the present study, the levels of toxic heavy metals (Cd, Pb and Al) as well as trace and essential metals (B, Ba, Co, Cu, Cr, Fe, Li, Mn, Mo, Ni, Sr, V and Zn) and macronutrients (Ca, K, Mg, Na) have been quantified in two species of fish for human consumption. In order to do this, a total of 80 muscle samples and 80 liver samples, belonging to two species of osteichthyes (bony fish), Diplodus sargus cadenati and Sparisoma cretense, were analyzed. The specimens studied were captured on the north coast of Gran Canaria (Canary Islands) using recreational fishing techniques. As they caught from the shore, the data obtained respond to the need to assess the toxic levels in two representative species of artisanal and recreational fishing in the area. The risk assessment indicated that these two fish species are safe for the average consumer; however, if the livers are frequently consumed, there may be potential risks because they exceed the Admissible Daily Intakes for Pb and Cd.