Copper, lead and cadmium monitoring via the Small-spotted catshark (Scyliorhinus canicula; Linnaeus, 1758): space-time driven variability in Western Mediterranean populations

doi:10.21203/rs.3.rs-3210738/v1

The philopatric and sedentary nature of female Scyliorhinus canicula, its high abundance as a bycatch and resilience to regular exploitation by bottom trawl fisheries and its widespread distribution, make it a potentially good candidate as a biomonitor species. To evaluate this potential, Microwave Assisted Extraction (MAE) and Graphite Furnace Atomic Absorption Spectrometry (GF-AAS) were used to analyse Pb, Cd and Cu in muscle tissue of individuals captured in the Western Mediterranean (Alicante, Spain). A monthly assessment of the concentration of these three analytes was conducted from November 2019 to November 2020 with 300 individuals. Results showed the existence of slightly higher mean concentrations during warmer seasons for Pb and Cd with mean concentrations for Pb and Cu peaking in Autumn 2019 and during Spring 2020 in the case of Cd. Significant differences in analyte concentrations found between non-consecutive months suggested gradual variability in time. Although space-wise, time-persistent concentration hotspots were observed throughout the sample area, the magnitude of these appeared to be variable in time and should be evaluated in future studies.

Heavy metal

Pollution

MAE

GFAAS

Scyliorhinus canicula

Biomonitor

The noxious nature of heavy metals toward human health requires the creation of regulations and instruments to control their concentrations in the environment as well as foodstuffs made available to consumers. Several organisations such as the Food and Agriculture Organisation of the United Nations (FAO), the World Health Organisation (WHO), the Environmental Protection Agency (EPA) and the Convention for the Protection of the Marine Environment of the North-East Atlantic (OSPAR), among others, have worked towards the establishment of maximum thresholds of heavy metal concentrations in foodstuff for their commercialisation and consumption. Perhaps, the most reliable and updated source of information in relation to this subject is the Codex Alimentarius, a document developed by the Joint FAO/WHO which constitutes the Expert Committee on Food Additives (JEFCA) and gathers the international food standards established by the JEFCA and the European commission regulations No 1881/2006 and No 629/2008.

According to the JEFCA, lead in fish must not exceed 0.3 µg·g-¹ wet weight, and 0.05 mg·Kg^− 1 wet weight for cadmium (Wu, 2014). Contaminants lacking public health significance such as copper, are not considered in the Codex Alimentarius or any actual law or regulation.

The enforcement of these thresholds throughout European waters could use instruments which may improve the monitoring of heavy metals throughout different fishing sites. Biomonitors understood as an organism (or a part of an organism or a community of organisms) that contains information on the quantitative aspects of the quality of the environment; are valuable tools for this same purpose since not only will they offer information on the quality of the environment they inhabit and the status of the ecosystems and trophic chains exposed to a particular xenobiotic but they could also offer relevant insights on food related consumer safety (Markert et al., 2003). Furthermore, biomonitor sample gathering may rely on other industries such as fisheries which have the potential of offering high quality, readily available samples at a lower cost compared to that of focused sampling. The use of elasmobranch as biomonitors could fulfil such purpose, acting as indicators of ocean health which may potentially detect the negative impact of pollutants before irreversible damage is caused (Alves et al., 2022).

It is for its biological and behavioural traits as well as its widespread distribution, relationship with fisheries and capability to accumulate xenoiotics that make the small-spotted catshark, Scyliorhinus canicula (Linnaeus, 1758) has a great potential to serve as a biomonitor. This demersal elasmobranch species can be found widespread throughout the Mediterranean and north-eastern Atlantic´s continental platform and the upper slopes (Ebert and Stehmann, 2013; Kousteni et al., 2015; Massutí and Moranta, 2003; Ruiz-García et al., 2023; Serena et al., 2020). This opportunistic predator´s diet has been found to be highly generalistic, being comprised mainly of crustaceans, molluscs, and teleosts (Barría et al., 2017; Kousteni et al., 2017; Lyle, 1983; Reinero et al., 2023; Valls et al., 2011). S. canicula captures are a common occurrence among Mediterranean fisheries within which, adults are occasionally targeted by fishermen due to their greater economic value, while younger individuals are generally discarded at sea (Barausse et al., 2014; Capapé et al., 2008; Carbonell et al., 2003). Despite being among the most captured elasmobranchs in the Mediterranean (Giovos et al., 2021), the Small-Spotted Catshark is known to display high post-capture recovery rates (Barragán-Méndez et al., 2019) which might be responsible for this species populations resilience toward fisheries (Peristeraki et al., 2020). In the Mediterranean, the length at 50% maturity has been found to be around 37.0–44.0 cm in males and females (Ivory et al., 2004).

Distribution patterns in this species appear to be size dependent, with mature individuals being more common in shallower waters (< 100 m) than juveniles (> 200 m) (Gouraguine et al., 2011); as well as consistent with male dispersal and female philopatry (Hueter et al., 2005; Sims et al., 2001; Sims, 2005), with genetic microsatellite, and mitochondrial markers; as well as genetic relatedness values, supporting such statement (Gubili et al., 2014; Kousteni et al., 2015; Manuzzi et al., 2019; Melis et al., 2023). Studies performed on Cantabrian Sea populations have registered individuals recaptured in the same area within one year of the original capture as well as limited movement ranges in 70% of the individuals under 24 Km from the site of first capture however, long term capture-recapture data gathered in Lough Hyne (South-West Ireland) have described residence periods of at least 7 years under specific geographical conditions (Rodrıguez-Cabello et al., 2004; Sims et al., 2001; Sims, 2005). The strong philopatric behaviour displayed by female individuals, along with their attachment to a particular area and relatively restricted movement range, could prove a useful trait that could support this species use for monitoring purposes.

Regarding S. canicula capability to incorporate Pb, Cd and Cu, studies performed on this species have described significant differences in all three elements muscle concentrations between individuals captured among areas with different levels of pollution, with even Pb, which concentrations tend to remain below detection limit, being detected in individuals from highly polluted areas (De Boeck et al., 2010; Vas, 1991). Moreover, a significant uptake of these analytes in muscle tissue was observed in S. canicula exposed to sublethal heavy metal concentrations when compared to individuals which were not exposed (De Boeck et al., 2010). Such findings corroborate this species capability to accumulate certain xenobiotics and could further support its aptitude for monitoring environmental purposes.

The limited economic interest of the fishing industry towards S. canicula regardless of its abundance among bottom trawl landings, poses a great opportunity for new research and further supports the species potential as a reliable, cost-efficient biomonitor. The present study is aimed towards the assessment of space-time variability of lead, cadmium, and copper concentrations in S. canicula muscle tissue in order to consider the use of this species as a heavy metal biomonitor.

A total of 300 Scyliorhinus canicula specimens were gathered throughout continental platform waters off the coast of the Marina Alta and Marina Baixa regions (Alicante, Spain) between November 2019 and November 2020 via commercial bottom trawlers from Calp´s fishing Guild (Fig. 1). Depth wise, the study area is characterised by a gentle depth gradient ranging from 60m to 250 m interrupted by a steep continental slope. Most of the trawls considered in this study took place between 60 and 200 m depth range with a maximum sampling depth of 400 m. Vessel GPS data was recorded for every haul performed during the sampling efforts.

All sampling was conducted in compliance with fishing quotas and biological standstills imposed over the studied area. Thus, monthly haul location within the sampling area was adapted to this premise. Only mature female specimens (> 40 cm ± 5 cm) were selected after every trawl. Samples were separated by date and trawl dependent lots and preserved at -18ºC until further processing was possible.

Sample Pretreatment and Analysis

Muscle samples were extracted and stored at -18ºC for at least 24 hours and subsequently oven dried at 60ºC for 48 hours or until constant weight was achieved. The resulting matrix was later blended to a thin powder using a domestic food processor and sieved trough a 50 µm mesh. The sieved powder was stored in polyethylene bags and preserved in a desiccator.

All glassware and materials involved in the analytical and pretreatment procedures were previously cleaned in a 10% HNO₃ acid bath. All reagents were provided by PANREAC (Barcelona, Spain). Heavy metal standards (Pb, Cd, Cu) were at an initial concentration of 1000 g·L^− 1 ± 0.002. A standard palladium solution (MERCK, Darmstadt, Germany) at a concentration of 1000 g·L^− 1 ± 0.002 was diluted to 500 mg·L^− 1 and used as a chemical matrix modifier. All dilutions were made using ultrapure bidistilled water.

Analyte extraction was performed via Microwave Assisted Extraction (MAE), using a CEM® MARS 6 microwave oven equipped with PTFE XPRESS digestion vessels. 1g of muscle matrix was digested along with 6 mL of Hyperpure HNO3 69% (v·v^− 1) and 2 mL of analytical grade H₂O₂ 33% (v·v^− 1) (PANREAC, Barcelona, Spain) in a 5-step power (W) controlled MAE procedure summarised in Table 1.

Table 1

MAE power-controlled acid extraction parameters.
Step	Power (W)	Time (min)
1	250	2
2	0	2
3	250	6
4	400	5
5	550	8

The resulting extracts were syringe filtered through a 0.45 µm mesh size Nylon filter and made up to 10 mL with ultrapure bidistilled water. All samples were then transferred to 12 mL sterile centrifuge tubes and preserved at 5ºC.

Cu, Cd and Pb were quantified within the samples via GFAAS (Varian® Model AA240Z). Analytical conditions for this procedure are summarised in Table 2.

Table 2

Analytical conditions for GFAAS
	Temperature ramp
Analyte	Drying and pyrolysis	Atomization	Matrix modifier	Graphite tube	λ(nm)
Cu	900ºC/8s	2300ºC/5s	N/a	NP	327.40
Pb	600ºC/17s	2100ºC/3s	Pd 500 ppm	NP	283.30
Cd	700ºC/22s	1800ºC/5s	Pd 500 ppm	NP	228.80
Inert Purge Gas Flow			0.3

Analyte concentrations were converted from dry weight to wet weight according to the equation:

$$\varvec{w}\varvec{w}=\varvec{D}\varvec{W}\varvec{*}[1-\left(\varvec{W}\varvec{P}\right)]$$

Where “ww” represents the wet weight concentrations, “DW” is the dry weight concentration of each sample and “WP” is the water percentage in muscles calculated per individual (Gaion et al., 2016; Gallo et al., 2023).

The technique´s analytical parameters and their corresponding calibration curves were obtained for each of the considered analytes. Calibration curves were generated by the spectroscopic analysis of standard solutions with known concentrations of each metal considered in this study. Results show linear correlation between the intervals 0.59–30.00 µg·L^− 1 for Cu, 0.12–30.00 µg·L^− 1 for Pb and 0.10–5.00 µg·L^− 1 for Cd in GFAAS. Additionally, a high correlation was observed in all cases (R₂ ≥ 0.999) as showed in Table 3. Limit of detection (LOD) and limit of quantification (LOQ) were also calculated according to the regulation (EC) 333/2007(58). Method validation was achieved using mussel tissue and dogfish liver certified reference materials (ERM®-CE278k and NRCC-DOLT-5).

Recovery values between 90% and 110% were accepted to validate digestion and analysis procedures (Türkmen et al., 2009). Mean recovery values can be observed in Table 3 (Bottom).

Table 3

Analytical parameters GFAAS and Analyte recovery values from Certified Reference Material analysis.
Analyte	RSD (%)	LOD (µg·L^− 1)^a	LOQ (µg·L^− 1)^b	LR (µg·L^− 1)^c	R²
Cu	1.23	0.03	0.11	0.3–30.0	1.0000
Pb	3.3	0.03	0.09	0.09-30.0	0.9996
Cd	2.7	0.003	0.01	0.01-5.00	0.9996
CRM	Cu (%)		Pb (%)	Cd (%)
ERM®-CE278k	94.70 ± 2.86		96.49 ± 3.84	99.40 ± 0.93
NRCC-DOLT-5	97.27 ± 2.20		99.81 ± 7.54	95.33 ± 4.97

* ^a Limit of Detection, ^b Limit of Quantification, ^c Linear Range

Data Processing and Statistical Analysis

All statistical analysis were carried out using GraphPad prism 7. Each dataset was tested for normality, using, Saphiro-Wilk´s test, which determined the dataset did not follow a normal distribution.

In order to assess analyte concentration variability over time throughout the sample area, mean haul concentration graphs were plotted (Fig. 2) and, since normality was not met in most datasets, a non-parametric Kruskal-wallis test and a multiple comparison, post hoc, Dunn´s test were performed. Significance was considered when the P < 0.05 criteria was met.

Heavy metal distribution throughout the sample area was evaluated using ArcMap 10.5. For this purpose, only trawls with mean analyte concentrations within the last decile of each element´s dataset was considered in order to pinpoint heavy metal concentration hotspots. High concentration areas were then pinpointed by generating circular minimum bounding geometries around the trawls. Depth data from the European Marine Observation Data Network (EMODnet) was used to plot bathymetric contours in the resulting maps.

Seasonal Variability

Overall, all three analyte concentrations remained relatively stable throughout the considered timeframe, with maximum mean monthly concentrations being observed during Autumn 2019 in the case of Pb and Cu (0.0502 ± 0.0164 and 0.416 ± 0.183 mg·kg^− 1ww respectively) and Spring 2020 in de case of Cd (0.0112 ± 0.0755 mg·kg^− 1ww). On the other hand, minimum mean Pb and Cu concentrations were observed during Autumn 2020 (0.0248 ± 0.00256 and 0.359 ± 0.182

mg·kg^− 1ww respectively) and Autumn 2019 for Cd (0.00644 ± 0.00444 mg·kg^− 1ww). Mean annual values for each element were 0.04052 mg·kg^− 1ww for Pb; 0.008516 mg·kg^− 1ww for Cd; and 0.3765 mg·kg^− 1ww for Cu.

Table 4

Mean wet weight (ww) analyte concentrations (mg·kg ^-1) and range found in muscle tissue per studied season. No outliers were included.
Month / Analyte	Pb	Cd	Cu
Autumn 2019	0.0502 ± 0.0164	0.00644 ± 0.00444	0.416 ± 0.184
Winter 2020	0.0439 ± 0.0285	0.00578 ± 0.00268	0.383 ± 0.173
Spring 2020	0.0379 ± 0.0214	0.0112 ± 0.00755	0.337 ± 0.211
Summer 2020	0.0385 ± 0.0154	0.00906 ± 0.00535	0.368 ± 0.134
Autumn 2020	0.0248 ± 0.00256	0.00929 ± 0.00411	0.359 ± 0.182

Concentration peaks above the threshold for safe human consumption tend to appear at a given time within very localised areas of the study site. In these areas and times, most individuals display considerably higher concentrations of one or several heavy metals when compared to those of specimens gathered elsewhere. These concentration peaks are not representative of most of the study area and have proved to be statistical outliers. Despite not being considered in the statistical analysis for temporal variability assessment, their presence should not be ignored, since it could imply the existence of localised heavy metal concentration hotspots and, therefore, their spatial distribution will be further explored in this study.

In order to assess analyte concentration variability over time, mean concentration graphs were plotted (Fig. 2). All three analyte concentrations in Scyliorhinus canicula muscle tissue remained relatively stable during the considered period and no significant concentration differences were observed between consecutive seasons. However, significant differences were found between certain non-consecutive seasons, implying, to some extent, high analyte temporal stability in S. canicula muscle tissue, with the same probably being true for analyte concentrations in the sediments and waters of study area. Regarding muscle Pb concentrations, significant differences were observed between Autumn 2019 and Spring 2020 (P < 0.0003). Weaker significant differences were found between Autumn 2019 and Autumn 2020 (P = 0.0438) and Autumn 2020 and Winter 2020 (P = 0.0479). Differences in Cd concentrations were found to be significant between Autumn 2019 and Spring 2020 (P = 0.0092) as well as Winter 2020, Spring 2020 (P < 0.0001) and Summer 2020 (P = 0.0064). Finally, regarding Cu concentrations, interseasonal differences observed were non-significant during the considered timeframe.

The non-consecutive seasonal differences observed in Cd and Pb concentrations suggest some degree of variability throughout the year, however, it is unclear if these follow an annual trend. Mean seasonal concentrations were plotted in Fig. 3 in order to compare this study´s results with those found in literature. Similarities have been found with the study performed by(Ghosn et al., 2020) which compared the concentration of Cu, Pb and Cd among other heavy metals between wet and dry seasons in three Eastern Mediterranean teleost species: Siganus rivulatus, Lithognathus mormyrus and Etrumeus teres. Despite not finding inter-seasonal significant differences in liver concentrations of the considered analytes, except for Pb in E. teres, mean concentrations tended to be higher in the warmer seasons (Spring-Summer) (Ghosn et al., 2020). Additionally, similar studies performed in Mediterranean waters on muscle tissues of Mullus barbatus by Soliman et al. (2021); on Solea solea and Sparus aurata byÇoğun et al. (2005) and on Sarda sarda, Trachurus trachurus and Merlangius merlangus byMendil et al. (2010) gathered results that coincided with those ofGhosn et al. (2020) for Pb, Cd and Cu. A similar pattern was observed in our study for Pb and Cd quantified in Scyliorhinus canicula muscle tissues for which mean concentrations tended to be slightly higher in Spring for Cd and Summer for Pb in comparison to colder seasons. the only exception to this apparent trend is Cu.

Similar studies performed on elasmobranch species in the Mediterranean sea and North Eastern Atlantic ocean, tend to focus on the spatial variability in trace element concentrations within these organism's tissues. Demersal species such as Galeus melastomus and Mustelus mustelus have been studied alongside S. canicula throughout Mediterranean waters.

Table 5. Mean values for Pb, Cd and Cu muscle tissue concentrations (mg·kg ^-1ww) from demersal elasmobranch species found in literature. Concentration values transformed when necessary to wet weight using the mean water percentage in muscle value for this study (80.36%) for S. canicula. TS = Tyrrhenian Sea, AS = Adriatic Sea, GoL = Gulf of Lion, BoB = Bay of Biscay, IS = Ionian Sea, SoS = Strait of Sicily

Species	Pb	Cd	Cu	Reference & Site
Scyliorhinus canicula	1.01	0.0334	1.687	(Filice et al., 2023) TS
	0.27	0.07	1.63	(Türkmen et al., 2009)
	0.00668	0.00177	0.314	(Mille et al., 2018) GoL
	0.00825	0.00177	0.157	(Mille et al., 2018) BoB
Galeus melastomus	0.104 – 0.126	0.0299 – 0.109	1.07 – 2.03	(Gallo et al., 2023) TS
	0.0193 - 0.0240	0 – 0.0193	0.565 – 1.702	(Gallo et al., 2023) SoS
	0.216	0.164	1.26	(Gaion et al., 2016) IS

0.010

0.000982

0.452

(Mille et al., 2018) GoL

0.00824

0.000982

0.137

(Mille et al., 2018) GoB

Mustelus

mustelus

0.06

0.01

0.71

(Storelli et al., 2011) AS

Analysis performed by Filice et al. (2023)d rkmen et al. (2009) on Scyliorhinus canicula on specimens gathered from the Tuscan archipelago in the Tyrrhenian Sea (Central Mediterranean sea) and the Aegean sea, showed muscle concentrations of all three elements that greatly surpassed mean annual values found in the present study. (Table 5). On the other hand, Pb, Cd and Cu concentrations observed by Mille et al. (2018) in S. canicula muscle tissues from the Gulf of Lion (Western Mediterranean) and the Gulf of Biscay (North Eastern Atlantic) were significantly lower than those found during this study (Table 5).

A comparison between the results gathered during this study and those obtained by Gaion et al. (2016), Mille et al. (2018),Gallo et al. (2023) and(Storelli et al., 2011) on the heavy metal content of Galeus melastomus and Mustelus mustelus muscle tissue reveals a similar trend, where samples gathered in Central and Eastern Mediterranean waters (Tyrrhenian, Adriatic and Ionian seas) display higher Pb, Cd and Cu concentrations than those gathered in the Western Mediterranean for all three species species regardless of the year each study was carried out. Furthermore, analyte concentrations observed in G. melastomus gathered from the GoL and the GoB were lower than those found in S. canicula during the present study. This suggests that, in this scenario, variables such as the species or each study´s timeframe might not affect trace element concentration as much as the sampling location.

The spatial distribution of the sampling site and its climatological specificities appear to heavily influence the severity of the seasonal heavy metal concentration variability as well as peak concentration months, especially in gill and liver tissue (Ghosn et al., 2020; Mathews et al., 2008; Mendil et al., 2010; Zuluaga Rodríguez et al., 2015). Variables such as water temperature and water chemistry are known to influence the uptake of heavy metals by marine biota and their environmental availability (Ghosn et al., 2020; Zuluaga Rodríguez et al., 2015). In addition, the main drivers of xenobiotic uptake and tissular variability are the species-specific accumulation dynamics as well as the stability of heavy metal concentrations within the diet, water, and sediments they are exposed to (James and Kleinow, 1994; Phillips and Rainbow, 1994; Zuluaga Rodríguez et al., 2015).

As observed by De Boeck et al. (2010) and Vas (1991), Scyliorhinus canicula muscle tissues display detectable levels if exposed to high enough concentrations of the considered analytes. Despite its limited sensibility, most samples analysed (86.3%) were above the limit of quantification for Pb and all surpassed it for Cd. These results imply that the matrix is sensitive enough to detect pollution hotspots, including areas with heavy metal concentration spikes, such as those found in the present study, some of which surpassed the maximum threshold for human consumption.

Spatial distribution of Pb, Cd and Cu

Pb, Cd and Cu annual spatial distribution among S. canicula populations was assessed by means of peak concentration plots which display the approximate location of potentially space-time persistent hotspots. Individuals displaying Pb concentrations within the tenth decile were gathered from 6 distinct trawls grouped into 2 nearby sites, located close to the edge of the continental platform and the beginning of the slope within a depth range of 100 to 450m (Fig. 3).

Note that despite displaying spatial proximity, most considered trawls were conducted during different months. The remaining trawls with mean concentrations bellow the tenth decile of the dataset, were both temporally and spatially close to the ones plotted in Fig. 3, nevertheless these displayed significantly lower concentrations. Such spatiotemporal behaviour may imply that the source of these hotspots is particularly localised, and its detection depends on the vessel´s course during the haul. Furthermore, the overlapping of hotspots derived from time distant trawls could suggest the existence of a common time persistent pollution source.

Regarding Cd distribution, two hotspots were found towards the edge of the continental shelf coinciding with those observed for Pb, and a third hot spot was observed closer to the coast, between 50 and 100 m deep (Fig. 4). The proximity of the latter to coastal waters could imply a greater involvement of anthropic pollution sources on the resulting Cd concentrations observed in S. canicula specimens however, further research is required to support this statement.

Cu concentration hotspots were widespread throughout the study site, occurring mainly between depths of 50 to 200m (Fig. 5).

Considering the greater abundance of Cu in the earth's crust compared with that of Pb and Cd, as well as its abundance within certain invertebrates, which comprise a considerable part of this species diet (Rainbow, 2018; Vas, 1991), the presence of Cu hotspots throughout the sample area is to be expected.

There is a knowledge gap regarding the distribution of Pb, Cd and Cu concentrations throughout the continental platform bottom waters and sediments of the studied area which supposes a handicap to stablish relationships between environmental concentrations and those found in Scyliorhinus canicula muscle tissues. It is noteworthy that the study area is subjected to heavy nautical traffic associated with the traffic separation scheme present within the studied area limits and a seasonal rise in peak touristic seasons, however, the effect these activities may have on heavy metal pollution is uncertain.

While temporal variability appears to be irregular throughout the studied timeframe, the existence of localised Pb and Cd hotspots, some of which coincide spatially, could imply the existence of a common source for both pollutants. With the exception of the isolated spikes, Scyliorhinus canicula consistently reflect temporally stable analyte hotspots, which supports the potential of this species for heavy metal monitorisation and encourages the development of future studies to correlate sediment and tissue pollutant concentration.

Nevertheless, further research on this species and on the cause for these hotspots must be carried out in order to fully assess the potential of the small spotted catshark as a biomonitor and to identify the nature of the analyte hotspots observed in the study site.

Regarding the reliability of bottom trawl fisheries as a means to gather samples for biomonitorisation purposes, it is true that high quality data can be gathered from such activities, however high bias is to be expected related to haul positioning and industry interests and restrictions which can affect the spatiotemporal homogeneity of sample gathering. On this regard, it is important to strictly select the trawls from which specimens are gathered to meet the requirements of the study.

Acknowledgements

This study forms part of the OCECOSVAL project (GVA-THINKINAZUL/2021/033) within the ThinkInAzul programme and was supported by MCIN with funding from European Union NextGenerationEU (PRTR-C17.I1) and by Generalitat Valenciana. This study was also supported by the Catholic University of Valencia through EDUCV PRE-2019 grant for in-training predoctoral research personnel as well as the 2021-159-001 and 2022-170-006 research aids. This study was further supported by IMEDMAR-UCV internal donations fund. Special thanks to Samuel Acevedo Quilis and Claudia Aragón Ferrer for their help and support.

Funding

This study forms part of the ThinkInAzul programme and was supported by MCIN with funding from European Union NextGenerationEU (PRTR-C17.I1) and by Generalitat Valenciana. This study was also supported by the Catholic University of Valencia through EDUCV PRE-2019-002 grant for in-training predoctoral research personnel as well as the 2021-159-001 and 2022-170-006 research aids. This study was further supported by IMEDMAR-UCV internal donations fund.

Competing Interests

The authors have no relevant financial or non-financial interests to disclose.

Author Contributions

Alejandro J. Molera Arribas, Ana M^a Hernández Martínez, Jose Rafael García March and Jose Tena Medialdea contributed to the study conception and design. Material preparation, data collection and analysis were performed by Alejandro J. Molera Arribas. The first draft of the manuscript was written by Alejandro J. Molera Arribas and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.

Ethical Approval

Biological samples involved in this study were obtained from deceased commercially available fish specimens gathered from commercial fisheries. Ethical approval is not applicable for this study.

Consent to Participate

Consent to participate is not applicable for this study.

Consent to Publish

All Authors give their consent for the publication of identifiable details within the manuscript.

Availability of Data and Materials

All data supporting the findings of this study are available within the paper and its Supplementary Information.

Alves LMF, Lemos MFL, Cabral H, Novais SC (2022) Elasmobranchs as bioindicators of pollution in the marine environment. Mar Pollut Bull 176:113418. https://doi.org/https://doi.org/10.1016/j.marpolbul.2022.113418
Barausse A, Correale V, Curkovic A, Finotto L, Riginella E, Visentin E, Mazzoldi C (2014) The role of fisheries and the environment in driving the decline of elasmobranchs in the northern Adriatic Sea. ICES J Mar Sci 71:1593–1603. https://doi.org/https://doi.org/10.1093/icesjms/fst222
Barragán-Méndez C, Ruiz-Jarabo I, Fuentes J, Mancera JM, Sobrino I (2019) Survival rates and physiological recovery responses in the lesser-spotted catshark (Scyliorhinus canicula) after bottom-trawling. Comp Biochem Physiol A Mol Integr Physiol 233:1–9. https://doi.org/https://doi.org/10.1016/j.cbpa.2019.03.016
Barría C, Navarro J, Coll M (2017) Trophic habits of an abundant shark in the northwestern Mediterranean Sea using an isotopic non-lethal approach. Estuar Coast Shelf Sci. https://doi.org/https://doi.org/10.1016/j.ecss.2017.08.021
Capapé C, Vergne Y, Reynaud C, Guélorget O, Quignard JP (2008) Maturity, fecundity and occurrence of the smallspotted catshark Scyliorhinus canicula (Chondrichthyes: Scyliorhinidae) off the Languedocian coast (southern France, north-western Mediterranean). Vie et milieu 58:47–55
Carbonell A, Alemany F, Merella P, Quetglas A, Román E (2003) The by-catch of sharks in the western Mediterranean (Balearic Islands) trawl fishery. Fish Res 61:7–18. https://doi.org/https://doi.org/10.1016/S0165-7836(02)00242-4
Çoğun H, Yüzereroğlu TA, Kargin F, Firat Ö (2005) Seasonal variation and tissue distribution of heavy metals in shrimp and fish species from the yumurtalik coast of iskenderun gulf, mediterranean. Bull Environ Contam Toxicol 75. https://doi.org/http://dx.doi.org/10.1007/s00128-005-0809-6
De Boeck G, Eyckmans M, Lardon I, Bobbaers R, Sinha AK, Blust R (2010) Metal accumulation and metallothionein induction in the spotted dogfish Scyliorhinus canicula. Comp Biochem Physiol A Mol Integr Physiol 155:503–508. https://doi.org/https://doi.org/10.1016/j.cbpa.2009.12.014
Ebert DA, Stehmann MFW (2013) Sharks, batoids and chimaeras of the North Atlantic. FAO, Roma. (Italia)
Filice M, Reinero FR, Cerra MC, Faggio C, Leonetti FL, Micarelli P, Giglio G, Sperone E, Barca D, Imbrogno S (2023) Contamination by Trace Elements and Oxidative Stress in the Skeletal Muscle of Scyliorhinus canicula from the Central Tyrrhenian Sea. Antioxidants 12, 524. https://doi.org/https://doi.org/10.3390/antiox12020524
Gaion A, Scuderi A, Sartori D, Pellegrini D, Ligas A (2016) Trace metals in tissues of Galeus melastomus Rafinesque, 1810 from the northern Tyrrhenian Sea (NW Mediterranean). Acta Adriat 57:165–172
Gallo S, Nania G, Caruso V, Zicarelli G, Leonetti FL, Giglio G, Fedele G, Romano C, Bottaro M, Mangoni O (2023) Bioaccumulation of Trace Elements in the Muscle of the Blackmouth Catshark Galeus melastomus from Mediterranean Waters. Biology (Basel) 12:951. https://doi.org/https://doi.org/10.3390/biology12070951
Ghosn M, Mahfouz C, Chekri R, Khalaf G, Guérin T, Jitaru P, Amara R (2020) Seasonal and spatial variability of trace elements in livers and muscles of three fish species from the Eastern Mediterranean. Environ Sci Pollut Res 27:12428–12438. https://doi.org/https://doi.org/10.1007/s11356-020-07794-5
Giovos I, Spyridopoulou RNA, Doumpas N, Glaus K, Kleitou P, Kazlari Z, Katsada D, Loukovitis D, Mantzouni I, Papapetrou M (2021) Approaching the “real” state of elasmobranch fisheries and trade: A case study from the Mediterranean. Ocean Coast Manag 211:105743. https://doi.org/https://doi.org/10.1016/j.ocecoaman.2021.105743
Gouraguine A, Hidalgo M, Moranta J, Bailey DM, Ordines F, Guijarro B, Valls M, Barberá C, De Mesa A (2011) Elasmobranch spatial segregation in the western Mediterranean. Sci Mar 75:653–664. https://doi.org/https://doi.org/10.3989/scimar.2011.75n4653
Gubili C, Sims DW, Veríssimo A, Domenici P, Ellis J, Grigoriou P, Johnson AF, McHugh M, Neat F, Satta A (2014) others, A tale of two seas: contrasting patterns of population structure in the small-spotted catshark across Europe. R Soc Open Sci 1, 140175. https://doi.org/https://doi.org/10.1098/rsos.140175
Hueter RE, Heupel MR, Heist EJ, Keeney DB (2005) Evidence of philopatry in sharks and implications for the management of shark fisheries. J Northwest Atl Fish Sci 35:239–247. https://doi.org/10.2960/J.v35.m493
Ivory P, Jeal F, Nolan CP (2004) Age determination, growth and reproduction in the lesser-spotted dogfish, Scyliorhinus canicula (L). J Northwest Atl Fish Sci 34:89–106. https://doi.org/10.2960/J.v35
James MO, Kleinow KM (1994) Trophic transfer of chemicals in the aquatic environment, in: Aquatic Toxicology and Cellular Perspectives. Lewis Publishers. Boca Raton, Florida, USA. pp. 1–35
Kousteni V, Karachle PK, Megalofonou P (2017) Diet of the small-spotted catshark Scyliorhinus canicula in the Aegean Sea (eastern Mediterranean). Mar Biol Res 13:161–173. https://doi.org/https://doi.org/10.1080/17451000.2016.1239019
Kousteni V, Kasapidis P, Kotoulas G, Megalofonou P (2015) Strong population genetic structure and contrasting demographic histories for the small-spotted catshark (Scyliorhinus canicula) in the Mediterranean Sea. Heredity (Edinb) 114:333. https://doi.org/10.1038/hdy.2014.107
Lyle JM (1983) Food and feeding habits of the lesser spotted dogfish, Scyliorhinus canicula (L.), in Isle of Man waters. J Fish Biol 23:725–737. https://doi.org/https://doi.org/10.1111/j.1095-8649.1983.tb02950.x
Manuzzi A, Zane L, Muñoz-Merida A, Griffiths AM, Veríssimo A (2019) Population genomics and phylogeography of a benthic coastal shark (Scyliorhinus canicula) using 2b-RAD single nucleotide polymorphisms. Biol J Linn Soc 126:289–303. https://doi.org/https://doi.org/10.1093/biolinnean/bly185
Markert BA, Breure AM, Zechmeister HG (2003) Definitions, strategies and principles for bioindication/biomonitoring of the environment. Trace Metals and Other Contaminants in the Environment. Elsevier, pp 3–39
Massutí E, Moranta J (2003) Demersal assemblages and depth distribution of elasmobranchs from the continental shelf and slope off the Balearic Islands (western Mediterranean). ICES J Mar Sci 60:753–766. https://doi.org/https://doi.org/10.1016/S1054-3139(03)00089-4
Mathews T, Fisher NS, Jeffree RA, Teyssié J (2008) Assimilation and retention of metals in teleost and elasmobranch fishes following dietary exposure 360. 1–12. https://doi.org/10.3354/meps07462
Melis R, Vacca L, Cariani A, Carugati L, Cau A, Charilaou C, Di Crescenzo S, Ferrari A, Follesa MC, Hemida F (2023) Commercial sharks under scrutiny: Baseline genetic distinctiveness supports structured populations of small-spotted catsharks in the Mediterranean Sea. Front Mar Sci 10:1050055. https://doi.org/https://doi.org/10.3389/fmars.2023.1050055
Mendil D, Demirci Z, Tuzen M, Soylak M (2010) Seasonal investigation of trace element contents in commercially valuable fish species from the Black sea, Turkey. Food Chem Toxicol 48:865–870. https://doi.org/https://doi.org/10.1016/j.fct.2009.12.023
Mille T, Cresson P, Chouvelon T, Bustamante P, Brach-Papa C, Bruzac S, Rozuel E, Bouchoucha M (2018) Trace metal concentrations in the muscle of seven marine species: Comparison between the Gulf of Lions (North-West Mediterranean Sea) and the Bay of Biscay (North-East Atlantic Ocean). Mar Pollut Bull 135:9–16. https://doi.org/https://doi.org/10.1016/j.marpolbul.2018.05.051
Peristeraki P, Tserpes G, Kavadas S, Kallianiotis A, Stergiou KI (2020) The effect of bottom trawl fishery on biomass variations of demersal chondrichthyes in the eastern Mediterranean. Fish Res 221:105367. https://doi.org/https://doi.org/10.1016/j.fishres.2019.105367
Phillips DJH, Rainbow PS (1994) Biomonitoring of trace aquatic contaminants. Chapman & Hall, p 371
Rainbow PS (2018) Heavy metal levels in marine invertebrates. Heavy Met Mar Environ 67–79
Reinero FR, Becerril-García EE, Elorriagaverplancken FR, Melo-Barrera FN, Toraldo-Serra ML, Giglio G, Micarelli P, Tripepi S, Galván-Magaña F, Sperone E (2023) Stable isotopes provide evidence of a trophic shift in the lesser spotted dogfish Scyliorhinus canicula from the Central Tyrrhenian Sea. Mediterr Mar Sci 24:1–6. https://doi.org/https://doi.org/10.12681/mms.27391
Rodrıguez-Cabello C, Sánchez F, Fernández A, Olaso I (2004) Is the lesser spotted dogfish (Scyliorhinus canicula) population from the Cantabrian Sea a unique stock? Fish Res 69:57–71. https://doi.org/https://doi.org/10.1016/j.fishres.2004.04.002
Ruiz-García D, Raga JA, March D, Colmenero AI, Quattrocchi F, Recasens L, Barría C (2023) Spatial distribution of the demersal chondrichthyan community from the western Mediterranean trawl bycatch. https://doi.org/https://doi.org/10.3389%2Ffmars.2023.1145176
Serena F, Abella AJ, Bargnesi F, Barone M, Colloca F, Ferretti F, Fiorentino F, Jenrette J, Moro S (2020) Species diversity, taxonomy and distribution of Chondrichthyes in the Mediterranean and Black Sea. Eur Zool J 87:497–536. https://doi.org/https://doi.org/10.1080/24750263.2020.1805518
Sims D, Nash J, Morritt D (2001) Movements and activity of male and female dogfish in a tidal sea lough: alternative behavioural strategies and apparent sexual segregation. Mar Biol 139:1165–1175. https://doi.org/10.1007/s002270100666
Sims DW (2005) Differences in habitat selection and reproductive strategies of male and female sharks, in: Sexual Segregation in Vertebrates. Cambridge University Press, p. 127
Soliman Y, Saad A, Hammoud V, Capapé C (2021) Heavy metal concentrations in tissues of red mullet, mullus barbatus (mullidae) from the syrian coast (eastern mediterranean sea), in: Annales: Series Historia Naturalis. Scientific and Research Center of the Republic of Slovenia, pp. 243–250. https://doi.org/10.19233/ASHN.2021.29
Storelli MM, Cuttone G, Marcotrigiano GO (2011) Distribution of trace elements in the tissues of smooth hound Mustelus mustelus (Linnaeus, 1758) from the southern–eastern waters of Mediterranean Sea (Italy). Environ Monit Assess 174:271–281
Türkmen M, Türkmen A, Tepe Y, Töre Y, Ate\cs A (2009) Determination of metals in fish species from Aegean and Mediterranean seas. Food Chem 113:233–237. https://doi.org/https://doi.org/10.1016/j.foodchem.2008.06.071
Valls M, Quetglas A, Ordines F, Moranta J (2011) Feeding ecology of demersal elasmobranchs from the shelf and slope off the Balearic Sea (western Mediterranean). Sci Mar 75:633–639. https://doi.org/10.3989/scimar.2011.75n4633
Vas P (1991) Trace metal levels in sharks from British and Atlantic waters. Mar Pollut Bull 22:67–72. https://doi.org/https://doi.org/10.1016/0025-326X(91)90138-I
Wu Y (2014) General standard for contaminants and toxins in food and feed. International Food Standards
Zuluaga Rodríguez J, Gallego Ríos SE, Ramírez Botero CM (2015) Content OF Hg, Cd, Pb and as in fish species: A review. https://doi.org/10.17533/udea.vitae.v22n2a09. Vitae

SuplementaryData.xlsx

Copper, lead and cadmium monitoring via the Small-spotted catshark (Scyliorhinus canicula; Linnaeus, 1758): space-time driven variability in Western Mediterranean populations

Status:

Journal Publication

Version 1

Abstract

Figures

Introduction

Materials & Methods

Sample Pretreatment and Analysis

* ^a Limit of Detection, ^b Limit of Quantification, ^c Linear Range

Data Processing and Statistical Analysis

Results and Discussion

Seasonal Variability

Spatial distribution of Pb, Cd and Cu

Conclusions

Declarations

References

Supplementary Files

Status:

Journal Publication

Version 1

Copper, lead and cadmium monitoring via the Small-spotted catshark (Scyliorhinus canicula; Linnaeus, 1758): space-time driven variability in Western Mediterranean populations

Status:

Journal Publication

Version 1

Abstract

Figures

Introduction

Materials & Methods

Sample Pretreatment and Analysis

* a Limit of Detection, b Limit of Quantification, c Linear Range

Data Processing and Statistical Analysis

Results and Discussion

Seasonal Variability

Spatial distribution of Pb, Cd and Cu

Conclusions

Declarations

References

Supplementary Files

Status:

Journal Publication

Version 1

* ^a Limit of Detection, ^b Limit of Quantification, ^c Linear Range