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Carballeira C.,University of Cadiz | Martin-Diaz L.,University of Cadiz | Martin-Diaz L.,Campus Universitario Of Puerto Real | DelValls T.A.,University of Cadiz
Marine Environmental Research | Year: 2011

Sea urchin embryo-larval development (ELD) and fertilization tests have been widely used in ecotoxicity studies and are included in regulatory frameworks. Biological processes occur naturally within a range of salinity that depends on the species considered. In an attempt to determine the optimum range of salinity, ELD and fertilization bioassays were performed at different salinities (15-40.5‰) with two species of Atlantic sea urchin: Arbacia lixula and Paracentrotus lividus. In the ELD assay, the optimum range of salinity was wider for A. lixula (29-35.5‰) than for P. lividus (29-33‰). In the fertilization assay with P. lividus as a bioindicator species, the highest percentage of fertilization (90%) was obtained at salinities of between 29 and 33‰. More research on A. lixula is required, since the fertilization success was below 60%. The results of the present study demonstrate that salinity may be a confounding factor in interpreting ELD test results. © 2011 Elsevier Ltd.

Carballeira C.,University of Cadiz | Ramos-Gomez J.,University of Santiago de Compostela | Martin-Diaz M.L.,University of Cadiz | Martin-Diaz M.L.,Campus Universitario Of Puerto Real | And 2 more authors.
Journal of Environmental Monitoring | Year: 2012

The increase in aquaculture activities in the last few decades has not been accompanied by a corresponding increase in environmental controls and regulations. In this context, the application of environmental monitoring plans (EMPs) has become necessary to assess the environmental impact associated with fish farming wastes. The objective of this review paper is to evaluate the suitability of experimental and analytical procedures as monitoring tools for inclusion in EMPs for intensive land-based marine fish farms (LBMFFs). The strong hydrodynamics and, in particular, the lack of sediment on the rocky coasts where LBMFFs are usually located, greatly limit the monitoring tools that can be used. We propose EMPs that employ a weight-of-evidence approach to evaluate: contamination, trophic and toxic effects, and ecological integrity. Laboratory tests, in situ bioassays and field surveys of local species are presented as key tools for assessing the impact of LBMFFs on ecosystems. The δ15N signal along a spatial gradient is proposed for evaluating exposure to contaminants. Trophic effects can be determined by growth of transplanted macro- and microalgae. Toxic effects can be evaluated by responses at different levels of biological organization, including biochemical and histological changes, physiological alterations and survival, in species from different trophic levels. Fouling tests and analysis of community structures are recommended for assessing ecological integrity. This review contributes to the development of environmental controls for intensive LBMFFs, and for other activities that discharge wastewater to rocky shores. © 2012 The Royal Society of Chemistry.

Martin-Robles A.J.,University of Cadiz | Martin-Robles A.J.,Campus Universitario Of Puerto Real | Aliaga-Guerrero M.,Campus Universitario Of Puerto Real | Whitmore D.,University College London | And 2 more authors.
Chronobiology International | Year: 2012

Circadian rhythms are established very early during vertebrate development. In fish, environmental cues can influence the initiation and synchronization of different rhythmic processes. Previous studies in zebrafish and rainbow trout have shown that circadian oscillation of clock genes represents one of the earliest detectable rhythms in the developing embryo, suggesting their significance in regulating the coordination of developmental processes. In this study, we analyzed the daily expression of the core clock components Per1, Per2, Per3, and Clock during the first several days of Senegalese sole development (04 d post fertilization or dpf) under different lighting regimes, with the aim of addressing when the molecular clock first emerges in this species and how it is affected by different photoperiods. Rhythmic expression of the above genes was detected from 0 to 1 dpf, being markedly affected in the next few days by both constant light (LL) and dark (DD) conditions. A gradual entrainment of the clock machinery was observed only under light-dark (LD) cycles, and robust rhythms with increased amplitudes were established by 4 dpf for all clock genes currently studied. Our results show the existence of an embryonic molecular clock from the 1st d of development in Senegalese sole and emphasize the significance of cycling LD conditions when raising embryos and early larvae. Copyright © Informa Healthcare USA, Inc.

Martin-Robles A.J.,University of Cadiz | Martin-Robles A.J.,Campus Universitario Of Puerto Real | Whitmore D.,University College London | Pendon C.,University of Cadiz | Munoz-Cueto J.A.,Campus Universitario Of Puerto Real
Chronobiology International | Year: 2013

Studies on the developmental onset of the teleost circadian clock have been carried out in zebrafish and, recently, in rainbow trout and Senegalese sole, where rhythms of clock gene expression entrained by light-dark (LD) cycles have been reported from the first days post fertilization. However, investigations of molecular clock rhythms during crucial developmental phases such as metamorphosis are absent in vertebrates. In this study, we documented the daily expression profile of Per1, Per2, Per3, and Clock during Senegalese sole pre-, early-, middle-, and post-metamorphic stages under LD 14:10 cycles (LD group), as well as under transient exposure to constant light (LL-LD group) or constant dark (DD-LD group) conditions. Our results revealed that robust rhythms of clock genes were maintained along the metamorphic process, although with declining amplitudes and expression levels. All daily profiles were affected by transient constant conditions, in particular Per1, Per3, and Clock amplitudes and Per2 acrophase. Rhythm parameters were progressively restored upon reversion to LD cycles but even after 9 d under cycling conditions, a prolonged effect on clock function was observed, especially in the LL-LD group. These results reflect the differential sensitivity of clock machinery of sole to transitory light cues, being Per1 and Per3 predominantly clock regulated and supporting the role of Per2 as part of the light input pathway. Interestingly, there is no reversal in the phase of clock gene rhythms between pre- and post-metamorphic animals that would be coincident with the switch from diurnal to nocturnal locomotor activity, which occurs in this species just before the beginning of this process. Whether specialized central pacemakers dictate the phase of locomotor activity or this control is exerted outside of the core clock mechanism remains to be elucidated. Our results emphasize the importance of maintaining cycling light-dark conditions in aquaculture practices during ontogeny of Senegalese sole. © Informa Healthcare USA, Inc.

Servili A.,University of Cadiz | Servili A.,Institute Federatif Of Recherche 140 | Herrera-Perez P.,University of Cadiz | Herrera-Perez P.,Campus Universitario Of Puerto Real | And 3 more authors.
General and Comparative Endocrinology | Year: 2012

The European sea bass expresses three GnRH (Gonadotrophin Releasing Hormone) forms that exert pleiotropic actions via several classes of receptors. The GnRH-1 form is responsible for the endogenous regulation of gonadotrophin release by the pituitary gland but the role of GnRH-2 and GnRH-3 remains unclear in fish. In a previous study performed in sea bass, we have provided evidence of direct links between the GnRH-2 cells and the pineal organ and demonstrated a functional role for GnRH-2 in the modulation of the secretory activity of this photoreceptive organ. In this study, we have investigated the possible relationship between the GnRH-3 system and the retina in the same species. Thus, using a biotinylated dextran-amine tract-tracing method, we reveal the presence of retinopetal cells in the terminal nerve of sea bass, a region that also contains GnRH-3-immunopositive cells. Moreover, GnRH-3-immunoreactive fibers were observed at the boundary between the inner nuclear and the inner plexiform layers, and also within the ganglion cell layer. These results strongly suggest that the GnRH-3 neurons located in the terminal nerve area represent the source of GnRH-3 innervation in the retina of this species. In order to clarify whether the retina is a target for GnRH, the expression pattern of GnRH receptors (dlGnRHR) was also analyzed by RT-PCR and in situ hybridization. RT-PCR revealed the retinal expression of dlGnRHR-II-2b, -1a, -1b and -1c, while in situ hybridization only showed positive signals for the receptors dlGnRHR-II-2b and -1a. Finally, double-immunohistochemistry showed that GnRH-3 projections reaching the sea bass retina end in close proximity to tyrosine hydroxylase (dopaminergic) cells, which also expressed the dlGnRHR-II-2b receptor subtype. Taken together, these results suggest an important role for GnRH-3 in the modulation of dopaminergic cell activities and retinal functions in sea bass. © 2011 Elsevier Inc.

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