Browsing by Author "Cancio, Ibon"
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- Otolith shape and elemental signatures provide insights into the connectivity of euryhaline chelon labrosus inhabiting two close estuaries with different burdens of xenoestrogens in the southern bay of biscayPublication . Nzioka, Anthony; Cancio, Ibon; Cerio, Oihane Diaz de; Pinto, Edgar; Almeida, Agostinho; Correia, Alberto TeodoricoIntersex gonads have been observed in thicklip grey mullet Chelon labrosus, inhabiting estuaries with high burdens of xenoestrogens in the Southeast Bay of Biscay, but knowledge of population connectivity among estuaries is lacking for this euryhaline fish species. This study investigates the population structure of C. labrosus using otolith shape and elemental signatures of 60 adults (overall length ~ 38 cm) from two estuaries 21 nautic miles apart, one with a high incidence of intersex condition (Gernika), and the other one pristine (Plentzia). Otolith shape analyses were performed using elliptical Fourier descriptors, while elemental signatures of whole sagittae were obtained by inductively coupled plasma mass spectrophotometry. Univariate and multivariate statistics were applied to determine if otolith signatures show patterns of homogeneity between estuaries. The data indicated significant differences in the otolith shape and elemental composition between mullets of Gernika and Plentzia. Elemental differences were mainly driven by Sr, Li (both higher in Plentzia) and Ba (higher in Gernika). The 98% re-classification success rate obtained from stepwise linear discriminant function analysis suggests that Gernika and Plentzia individuals form separated population units. The limited connectivity between these two close estuaries would indicate a different life history of exposure to chemicals, which might explain the high prevalence of intersex condition in Gernika and its absence in Plenztia.
- Use of otolith shape and elemental signatures to infer the population structure of the Thicklip Grey Mullet Chelon labrosus in the Southern Bay of BiscayPublication . Nzioka, Anthony; Cancio, Ibon; Diaz De Cerio, Oihane; Ortiz-Zarragoitia, Maren; Pinto, Edgar; Almeida, Agostinho; Correia, Alberto TeodoricoXenoestrogenic effects have been reported in thicklip grey mullet, Chelon labrosus, used as pollution sentinel organisms in estuaries in the Southeast Bay of Biscay with intersex gonads described in populations from some contaminated estuaries. Despite evidence of reproductive stress in this catadromous fish species, knowledge of mullet reproductive movements and connectivity between estuaries is lacking. This study investigates the population structure of C. labrosus using otolith shape and elemental signatures of 60 adult individuals collected from two estuaries found in the Southeast Bay of Biscay (Gernika and Plentzia). All samples were collected in June–July 2020. Otolith shape analysis was determined using elliptical Fourier descriptors, while elemental signatures (Sr:Ca, Li:Ca, Mg:Ca, Mn:Ca, Co:Ca, Ni:Ca, Cu:Ca and Ba:Ca) of whole sagittae were determined by inductively coupled plasma mass spectrophotometry. Both natural tags were analyzed with univariate and multivariate statistics to determine whether these signatures are geographically distinct and can be used to assess the degree of separation between individuals. The data showed significant differences in the otolith shape and elemental analyses, with canonical analysis of principal coordinates plots identifying two different groups, each one belonging to each estuary of origin. Differences in whole otolith elemental signatures between locations were driven by Sr:Ca, Li:Ca, and Ba:Ca. Sr:Ca and Li:Ca ratios were higher in Plentzia than in Gernika, while Ba:Ca was higher in Gernika. The high re-classification success rate using both tools obtained from stepwise linear discriminant function analysis supports these findings and suggests that Gernika and Plentzia individuals passed enough time in separated water compartments and should be regarded as two different population units. This could suggest that the intersex condition in mullets from Gernika is due to life-long exposure to xenoestrogens after homing during early larval development in that estuary, without migrations to other estuaries.