Metal bioaccumulation pattern by Cotylorhiza tuberculata (Cnidaria, Scyphozoa) in the Mar Menor coastal lagoon (SE Spain)

Long-term sediment records reveal over three thousand years of heavy metal inputs in the Mar Menor coastal lagoon (SE Spain)

The Mar Menor lagoon combined high biological production and environmental quality, making it an important economic engine. However, the pressure of human activities put its ecological integrity at risk, the oldest environmental impact being mining activity recorded since Roman times, about 3500 years ago, reaching its maximum intensity in the 20th century, contributing heavy metals to the lagoon sediments for almost 30 centuries. This work reviews the spatiotemporal evolution of the main heavy metals in this coastal lagoon using data from 272 surface sediment samples obtained during the last 40 years and two deep cores covering the total history of the lagoon (c. 6500 yrs BP), so as their incidence in the lagoon trophic web. The observed patterns in sedimentation, sediment characteristics and heavy metal content respond to the complex interaction, sometimes synergistic and sometimes opposing, between climatic conditions, biological production and human activities, with mining being mainly responsible for Pb, Zn and Cd inputs and port activities for Cu. High Fe/Al, Ti/Al and Zr/Al ratios identify periods of mining activity, while periods of arid climatic conditions and deforestation that increase erosion processes in the drainage basin and silt concentration in the lagoon sediments are determined by high Zr/Rb and, to a lesser extent, Zr/Al and Si/Al ratios. After the cessation of direct discharges into the lagoon in the 1950s, the recent evolution of heavy metals concentration and its spatial redistribution would be determined by hydrographic and biogeochemical processes, solubility of different elements, and coastal works in harbours and on beaches. The bioconcentration factor decreases along the trophic levels of the food web, suggesting that the lagoon ecosystem provides an important service by retaining heavy metals in the sediment, largely preventing their bioavailability, but actions involving resuspension or changes in sediment conditions would pose a risk to organisms.

Factors structuring microbial communities in highly impacted coastal marine sediments (Mar Menor lagoon, SE Spain)

Coastal marine lagoons are environments highly vulnerable to anthropogenic pressures such as agriculture nutrient loading or runoff from metalliferous mining. Sediment microorganisms, which are key components in the biogeochemical cycles, can help attenuate these impacts by accumulating nutrients and pollutants. The Mar Menor, located in the southeast of Spain, is an example of a coastal lagoon strongly altered by anthropic pressures, but the microbial community inhabiting its sediments remains unknown. Here, we describe the sediment prokaryotic communities along a wide range of environmental conditions in the lagoon, revealing that microbial communities were highly heterogeneous among stations, although a core microbiome was detected. The microbiota was dominated by Delta- and Gammaproteobacteria and members of the Bacteroidia class. Additionally, several uncultured groups such as Asgardarchaeota were detected in relatively high proportions. Sediment texture, the presence of Caulerpa or Cymodocea, depth, and geographic location were among the most important factors structuring microbial assemblages. Furthermore, microbial communities in the stations with the highest concentrations of potentially toxic elements (Fe, Pb, As, Zn, and Cd) were less stable than those in the non-contaminated stations. This finding suggests that bacteria colonizing heavily contaminated stations are specialists sensitive to change.

Sea snail (Hexaplex trunculus) and sea cucumber (Holothuria polii) as potential sentinel species for organic pollutants and trace metals in coastal ecosystems

The seasonal bioaccumulation of trace metals, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and organochlorinated pesticides (OCPs) in sea snail (Hexaplex trunculus) and sea cucumber (Holothuria polii) from Mar Menor lagoon were characterised. The highest concentrations of p,p'-DDE were detected in the central and south part of Mar Menor lagoon. However, the highest concentrations of metals in sea snail and holothurians were detected in the influence area of El Beal wadi. Biomagnification factors (BMF) in sea snail from cockle (sea snail-cockle concentration ratio) were higher than 5 for metal and organochlorinated compounds. However, similar concentrations were observed in both species for PAHs due to gastropods capability of metabolising these pollutants. Consequently, sea snail is proposed as a sentinel for trace metals, PCBs and OCPs in the coastal lagoons, not only due to its bioaccumulation and biomagnification capacity but also the easy sampling and amply distribution in many coastal areas.

Trace Metals Do Not Accumulate Over Time in The Edible Mediterranean Jellyfish Rhizostoma pulmo (Cnidaria, Scyphozoa) from Urban Coastal Waters

Jellyfish as food represent a millennial tradition in Asia. Recently, jellyfish have also been proposed as a valuable source of protein in Western countries. To identify health risks associated with the potential human consumption of jellyfish as food, trace element accumulation was assessed in the gonads and umbrella tissues of the Mediterranean Rhizostoma pulmo (Macri, 1778), sampled over a period of 16 months along the shallow coastal waters a short distance from the city of Taranto, an area affected by metallurgic and oil refinery sources of pollution. Higher tissue concentrations of trace elements were usually detected in gonads than in umbrella tissue. In particular, significant differences in the toxic metalloid As, and in the metals Mn, Mo, and Zn, were observed among different tissues. The concentrations of vanadium were slightly higher in umbrella tissues than in gonads. No positive correlation was observed between element concentration and jellyfish size, suggesting the lack of bioaccumulation processes. Moreover, toxic element concentrations in R. pulmo were found below the threshold levels for human consumption allowed by Australian, USA, and EU Food Regulations. These results corroborate the hypothesis that R. pulmo is a safe, potentially novel food source, even when jellyfish are harvested from coastal areas affected by anthropogenic impacts.

The role of Cymodocea nodosa on the dynamics of trace elements in different marine environmental compartments at the Mar Menor Lagoon (Spain)

During mining activities historically developed at Sierra Minera (Cartagena-La Unión, Spain), high amounts of trace elements were discharged to the Mar Menor coastal lagoon mainly through El Beal Wadi. The objective of this study is to establish the role played by the Cymodocea nodosa in the coastal marine dynamics of trace elements at the mouth of the wadi. To this end, the content of nine trace elements (As, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn) in different marine environmental compartments (i.e. marine and coastal sediments, C. nodosa tissues collected from live seagrass and C. nodosa beach cast litter) at two different locations were determined by inductively coupled plasma atomic emission spectrometry. The results showed that the seagrass C. nodosa could mobilise part of the elements present in marine sediments and water, thereby causing their re-accumulation in the coastal sediments through the C. nodosa beach cast litter.

A Multi-screening Evaluation of the Nutritional and Nutraceutical Potential of the Mediterranean Jellyfish Pelagia noctiluca

The phylum Cnidaria is one of the most important contributors in providing abundance of bio- and chemodiversity. In this study, a comprehensive chemical investigation on the nutritional and nutraceutical properties of Mediterranean jellyfish Pelagia noctiluca was carried out. Also, compositional differences between male and female organisms, as well as between their main anatomical parts, namely bell and oral arms, were explored in an attempt to select the best potential sources of nutrients and/or nutraceuticals from jellyfish. With the exception of higher energy densities and total phenolic contents observed in females than males, no statistically significant differences related to the specimen's sex were highlighted for the other compound classes. Rather, the distribution of the investigated chemical classes varied depending on the jellyfish's body parts. In fact, crude proteins were more abundant in oral arms than bells; saturated fatty acids were more concentrated in bells than oral arms, whereas polyunsaturated fatty acids were distributed in the exact opposite way. On the other hand, major elements and trace elements demonstrated an opposite behavior, being the latter most accumulated in oral arms than bells. Additionally, important nutraceuticals, such as eicosapentaenoic and docosahexaenoic acids, and antioxidant minerals, were determined. Overall, obtained data suggest the potential employment of the Mediterranean P. noctiluca for the development of natural aquafeed and food supplements.

The cytotoxicity and genotoxicity of particulate and soluble hexavalent chromium in leatherback sea turtle lung cells

Hexavalent chromium [Cr(VI)] is a marine pollution of concern as recent studies show it has a global distribution, with some regions showing high Cr concentrations in marine animal tissue, and it is extensively used. Leatherback sea turtles (Dermochelys coriacea) are an endangered marine species that may experience prolonged exposures to environmental contaminants including Cr(VI). Human activities have led to global Cr(VI) contamination of the marine environment. While Cr(VI) has been identified as a known human carcinogen, the health effects in marine species are poorly understood. In this study, we assessed the cytotoxic and genotoxic effects of particulate and soluble Cr(VI) in leatherback sea turtle lung cells. Both particulate and soluble Cr(VI) induced a concentration-dependent increase in cytotoxicity. Next, using a chromosome aberration assay, we assessed the genotoxic effects of Cr(VI) in leatherback sea turtle lung cells. Particulate and soluble Cr(VI) induced a concentration-dependent increase in clastogenicity in leatherback sea turtle lung cells. These data indicate that Cr(VI) may be a health concern for leatherback sea turtles and other long-lived marine species. Additionally, these data provide foundational support to use leatherback sea turtles as a valuable model species for monitoring the health effects of Cr(VI) in the environment and possibly as an indicator species to assess environmental human exposures and effects.

Distribution of Cr and Pb in artificial sea water and their sorption in marine sediments: an example from experimental mesocosms

The uptake of two heavy metals (chromium and lead) in sediments in experimental mesocosms under exposure to different metal concentrations was evaluated by monitoring their concentrations over time both in seawater and in sediment. Two separate experiments under laboratory-controlled conditions were carried out for the two metals. Sediments were collected from a protected natural area characterized by low anthropic influence and were placed in mesocosms that were housed in aquaria each with seawater at a different metal concentration. At pre-established time intervals, seawater and sediment samples were collected from each mesocosm for chemical analyses. Quantification of chromium and lead concentration in seawater and sediment samples was carried out by atomic absorption spectrometer with graphite furnace. Low doses of chromium and lead (<1 mg L^-1) do not entail an uptake in sediments and waters. At doses ≥1 mg L^-1, evolution of concentrations over time shows significant differences between these two metals: (i) chromium absorption from seawater is twice faster than lead; (ii) lead accumulates in considerable amount in sediments. The different behaviour of the two investigated heavy metals could be ascribed to different interactions existing between metal ions and different components of sediment.

Patterns of trace element bioaccumulation in jellyfish Rhizostoma pulmo (Cnidaria, Scyphozoa) in a Mediterranean coastal lagoon from SE Spain

The effects of an abandoned mining area, exploited for centuries in the mining district of Cartagena-La Union, result in a continuous supply of heavy metals into the Mar Menor coastal lagoon after rain episodes. As a consequence, concentration of trace elements in water column and sediments of this ecosystem is usually higher than in other areas. For monitoring ecosystem health, this study assessed the ability of Rhizostoma pulmo to bioaccumulate trace elements. A total of 57 individuals were sampled at eight different sampling stations during the summer of 2012. Although the concentrations of different analyzed elements (Al, Ti, Cr, Mn, Fe, Ni, Cu, Zn, As, Cd, Sn, and Pb) were moderate, bioconcentration levels in relation to seawater metal concentration were extremely high. In any case, the use or disposal of these organisms should consider their metal content, because of their potential environmental and health implications.