Microplastics (MPs) are thought to be ingested by a wide range of marine organisms before being excreted. However, several studies in marine organisms from different taxa have shown that MPs and nanoplastics could be translocated in other organs. In this study, we investigated the presence of MPs in the livers of commercial zooplanktivorous fishes collected in the field. The study focuses mainly on the European anchovy Engraulis encrasicolus but concerns also the European pilchard Sardina pilchardus and the Atlantic herring Clupea harengus. Two complementary methodologies were used to attest the occurrence of MPs in the hepatic tissue and to exclude contamination. 1) MPs were isolated by degradation of the hepatic tissue. 2) Cryosections were made on the livers and observed in polarized light microscopy. Both methods separately revealed that MPs, mainly polyethylene (PE), were translocated into the livers of the three clupeid species. In anchovy, 80 per cent of livers contained relatively large MPs that ranged from 124 μm to 438 μm, showing a high level of contamination. Two translocation pathways are hypothesized: (i) large particles found in the liver resulted from the agglomeration of smaller pieces, and/or (ii) they simply pass through the intestinal barrier. Further studies are however required to understand the exact process.

Piscivorous species like the Little Penguin (Eudyptula minor) are particularly at risk of being negatively impacted by pollution due to their heightened exposure through aquatic food chains. Therefore, determining the concentration of heavy metals in the fish prey of seabirds is an essential component of assessing such risk. In this study, we report on arsenic, cadmium, mercury, lead and selenium concentrations in three fish species, which are known to comprise a substantial part of the diet of Little Penguins at the urban colony of St Kilda, Melbourne, Australia. Metal concentrations in the fish sampled were generally within the expected limits, however, arsenic and mercury were higher than reported elsewhere. Anchovy (Engraulis australis) and sandy sprat (Hyperlophus vittatus) contained higher Hg concentrations than pilchard (Sardinops sagax), while sandy sprat and pilchard contained more selenium. We present these findings together with metal concentrations in Little Penguin blood and faeces, sampled within weeks of the fish collection. Mercury concentrations were highest in the blood, while faeces and fish prey species contained similar concentrations of arsenic and lead, suggesting faeces as a primary route of detoxification for these elements. We also investigated paired blood - faecal samples and found a correlation for selenium only. Preliminary data from stable isotope ratios in penguin blood indicate that changes in penguin blood mercury concentrations cannot be explained by trophic changes in their diet alone, suggesting a variation of bioavailable Hg within this semi-enclosed bay.

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.

Endocrine disrupting chemicals (EDCs) are substances which disrupt normal functioning of the endocrine system by interfering with hormone regulated physiological pathways. Aquatic environments provide the ultimate reservoir for many EDCs as they enter rivers and the ocean via effluent discharges and accumulate in sediments. One EDC widely dispersed in municipal wastewater effluent discharges is 17α-ethynylestradiol (EE2), which is one of the most widely prescribed medicines. EE2 is a bio-active estrogen employed in the majority of oral contraceptive pill formulations. As evidence of the health risks posed by EDCs mount, there is an urgent need to improve diagnostic tools for monitoring the effects of pollutants. As the cost of high throughput sequencing (HTS) diminishes, transcriptional profiling of an organism in response to EDC perturbation presents a cost-effective way of screening a wide range of endocrine responses. Coastal pelagic filter feeding fish species analyzed using HTS provide an excellent tool for EDC risk assessment in the marine environment. Unfortunately, there are limited genome sequence data and annotation for many of these species including Pacific sardine (Sardinops sagax) and chub mackerel (Scomber japonicus), which limits the utility of molecular tools such as HTS to interrogate the effects of endocrine disruption. In this study, we carried out RNA sequencing (RNAseq) of liver RNA harvested from wild sardine and mackerel exposed for 5 h under laboratory conditions to a concentration of 12.5 pM EE2 in the tank water. We developed an analytical framework for transcriptomic analyses of species with limited genomic information. EE2 exposure altered expression patterns of key genes involved in important metabolic and physiological processes. The systems approach presented here provides a powerful tool for obtaining a comprehensive picture of endocrine disruption in aquatic organisms.

Concentrations of organophosphate esters (OPEs) plasticizers were analysed in the present study. Fifty-five fish samples belonging to three highly commercial species, European sardine (Sardina pilchardus), European anchovy (Engraulis encrasicolus), and European hake (Merluccius merluccius), were taken from the Western Mediterranean Sea. OPEs were detected in all individuals, except for two hake samples, with concentrations between 0.38 and 73.4 ng/g wet weight (ww). Sardines presented the highest mean value with 20.5 ± 20.1 ng/g ww, followed by anchovies with 14.1 ± 8.91 ng/g ww and hake with 2.48 ± 1.76 ng/g ww. The lowest OPE concentrations found in hake, which is a partial predator of anchovy and sardine, and the higher δ¹⁵N values (as a proxy of trophic position), may indicate the absence of OPEs biomagnification. Eleven out of thirteen tested OPEs compounds were detected, being diphenyl cresyl phosphate (DCP) one of the most frequently detected in all the species. The highest concentration values were obtained for tris(1,3-dichloro-2-propyl) phosphate (TDClPP), trihexyl phosphate (THP), and tris(2-butoxyethyl) phosphate (TBOEP), for sardines, anchovies, and hakes, respectively. The human health risk associated with the consumption of these fish species showing that their individual consumption would not pose a considerable threat to public health regarding OPE intake.

Fatty acids (FAs) composition, 24 persistent organic pollutants (POPs), and 16 trace elements were examined in small pelagic fish (sardine, anchovy, round sardinella, chub and horse mackerels) caught by a fishing fleet for more than three years in the eastern Mediterranean Sea. Five Unmix source profiles associated with both sources, such as overlapping diet, including low-niche marine organisms and inputs from the surrounding environmental compartments were resolved. Inorganic compounds were notably more abundant in fish tissue than organochlorine xenobiotics. Comparison with the values of toxicological parameters revealed that the examined fish species are safe for human consumption, while the content of FAs emphasized the studied species as a valuable source of nutrients. A significant linear correlation was not observed between the 18 FAs and lipophilic organochlorines. Based on the obtained database, future assessments of the quality of edible fish species and the aquatic environment of the eastern Mediterranean Sea, which is known as an important fishing ground, could be significantly improved.

High-risk contaminants, OCPs and PCBs, were investigated in marine fish from the Adriatic Sea, from which retail fish in Croatia is commonly sourced. The pollutant levels in sardine, horse and chub mackerel, anchovy and round sardinella were analysed based on a two-year sampling and the joint use of generally accepted statistics and advanced clustering methods − self-organizing maps (SOM) and decision tree analysis (DT). Both the SOM and DT suggested fish mass and length rather than fat along with α-HCH, p,p′-DDT, PCB-74 and PCB-189 to cause variable pollutant uptake among species. Main distinctions of sardines occur in coastal and off coast regions rather than in a particular fishing zone and they are associated with both fish characteristics, levels of γ-HCH and PCBs: −60, −105, −150, −170, and −189. The results, mutually compatible or in agreement, could be useful for the design and implementation of the abatement strategies of fish pollution.

We used the Ecopath with Ecosim ecosystem model to assess the future effects of multiple stressors on sardine and the Portuguese continental shelf ecosystem. We assessed individual and combined impacts of changes in sardine fishing pressure, biomass of sardine competitors and predators and sea surface temperature (SST). This study demonstrated that the greatest impact on sardine stock is caused by projected SST rise whose effect is dominant and detrimental to sardine stock regardless of other conditions, including sardine fishing at maximum sustainable yield (FMSY). The largest impact on ecosystem stability, maturity and diversity of flows was observed under the forced-biomass scenarios that simulate changes in biomass of sardine predators and competitors. Moreover, these stressors alongside FMSY are projected to play an important role in the future evolution of the sardine stock. Results presented in this study can assist long-term and strategic management of the Iberian sardine stock.

This paper aimed at evaluating the total mercury content in five common fish species from the western European Atlantic coastal waters, and the associated risk of consumption. Mercury concentrations in muscle of Atlantic mackerel (Scomber scombrus), Atlantic chub mackerel (Scomber colias), European anchovy (Engraulis encrasicolus), Atlantic horse mackerel (Trachurus trachurus) and European pilchard (Sardina pilchardus) ranged from 0.003 to 0.20 mg kg⁻¹ wet weight, and no significant differences were observed between the average concentration in each species. A significant increasing trend in mercury content with fish size was observed for all species (except for European anchovy), suggesting mercury bioaccumulation throughout their life cycle. Still, the mercury content was far below the European Food Safety Authority and World Health Organization food safety thresholds in all species, highlighting the low risk to human health due to the ingestion of these species and the importance of consumer options for risk reduction.

We quantified the incidence of microplastics in the gut contents of the European sardine (Sardina pilchardus) and anchovy (Engraulis encrasicolus) in the Northwestern Mediterranean Sea and tested which variables influence this abundance, including the prevalence of parasites (i.e., trematoda larvae and nematodes). We detected a 58% occurrence of microplastics ingestion in sardines and a 60% in anchovies. With respect to sardines, the individuals with lower body conditions were found to have the highest microplastics ingestion probabilities, whereas in anchovies such probabilities were observed in individuals with higher gonadosomatic indices and smaller size. The areas with the highest microplastics ingestion probabilities were the Gulf of Alicante for sardines and the Gulf of Lion - Ebro Delta for anchovies. Both species showed a positive relationship between parasites and microplastics ingestion. These results highlight that both parasitism and ingestion of microplastics are concerns for the health of marine stocks and human consumers.