Effects of industrial pollution on the reproductive biology of Squalius laietanus (Actinopterygii, Cyprinidae) in a Mediterranean stream (NE Iberian Peninsula)

Abstract

Mediterranean rivers are severely affected by pollutants from industry, agriculture and urban activities. In this study we examined how industrial pollutants, many of them known to act as endocrine disruptors (EDCs), could disturb the reproduction of the Catalan chub (Squalius laietanus). The survey was conducted throughout the reproductive period of S. laietanus (from March to July 2014) downstream an industrial WWTP located in the River Ripoll (NE Iberian Peninsula). Eighty fish (28 females and 52 males) were caught by electrofishing upstream and 77 fish (33 females and 44 males) downstream a WWTP. For both sexes, the gonadosomatic index (GSI) and gonadal histology were examined and related to water chemical analysis and fish biomarkers. Female fecundity was assessed using the gravimetric method. Fish from the polluted site showed enhanced biomarker responses involved in detoxification. Also, in the polluted site, lower GSI values were attained in both sexes and females displayed lower numbers of vitellogenic oocytes. Gonadal histology showed that all maturation stages of testicles and ovaries were present at the two study sites but fish males from the polluted site had smaller diameter seminiferous tubules. Water chemical analysis confirmed greater presence of EDCs in the river downstream the industrial WWTP. The chemicals benzotriazole and benzothiazole could be partially responsible for the observed alterations in the reproductive biology of S. laietanus.

Biochemical aspects of susceptibility to stressors in two small cyprinids Squalius laietanus and Barbus meridionalis from the NW Mediterranean

“…Comparisons of baseline enzymatic activities were made in fish sampled in a confirmed reference area, all considering the undeniable anthropogenic fingerprint of NW Mediterranean watercourses (Blanco et al 2019;Carbajal et al 2019;Colin et al 2016b;Maceda-Veiga et al 2013;Marqueño et al 2019;Soler et al 2020). Markers of neurotoxicity signs (AChE), protection (BuChE), energy metabolism (LDH and CS),…”

“…xenobiotic metabolism and antioxidant defences (Colin et al 2016a) were selected as suggestive of a particular microhabitat use and biochemical adaptation. Since fish were simultaneously sampled at the same site, physical and chemical water conditions (described in Soler et al 2020) and the ecological characteristics of the habitat were common and only the influence of the particular diet, habitat use and physiological traits of each species will dictate the differences observed. In fact, the analysis of PFAS revealed higher bioaccumulation in barbel as formerly described for other organic contaminants and metals in the same fish species from the same geographical area From a biochemical perspective, the relationship between baseline enzymatic activities and in vitro sensitivity to chemicals can provide an estimation of the fish susceptibility to xenobiotics (Sanchez-Nogue et al 2013;Ribalta et al 2015).…”

“…Among the first steps of biotransformation, stand out the induction of 7-ethoxyresorufin-O-deethylase (EROD) activity related to CYP1A (Whyte et al 2000) and benzyloxy-4[trifluoromethyl]-coumarin-O-debenzyloxylase (BFCOD) activity associated to CYP3A (Celander 2011). The combination of both markers in fish has been applied in freshwater fish studies (Blanco et al 2019;Quesada-Garcia et al 2013;Soler et al 2020). CEs are also phase I reactions involved in the hydrolysis of foreign chemicals as well as endogenous compounds (Wheelock et al 2008) with a particular high stoichiometric affinity for organophosphorus pesticides for which a protective role, preventing AChE inhibition, has been awarded (Sanchez-Hernandez and Wheelock 2009).…”

“…In the particular case of the small Ripoll river, the physical and biotic community characterisation (Colin et al 2016b), the presence of bioaccumulated metals (Maceda-Veiga et al 2012;2013;Merciai et al 2014) and that of organic contaminants (Blanco et al 2019;Soler et al 2020) in water and/or in fish has been previously documented.…”

Improving water quality does not guarantee fish health: effects of ammonia pollution on the behaviour of wild-caught pre-exposed fish

“…Although ammonia is not the only pollutant present at these two sites, it is one of the most frequently found, not only in this river but in all rivers of NE Spain [2]. Table 1 shows the physical-chemical parameters analyzed at the two sites for the sampling month for Granollers Town Council (polluted site) and Fortuño et al [32] (unpolluted site). Other contaminants such as contaminants of emerging concern (CEC) (pesticides, metals, industrial solvents, pharmaceuticals and personal care products), could be found in other sites across these basin [32].…”