In situ experiments to assess effects of constraints linked to caging on ecotoxicity biomarkers of the three-spined stickleback (Gasterosteus aculeatus L.)

Abstract

The aim of this study was to evaluate the effects of caging constraints on multiple fish biomarkers used during ecotoxicological studies (biometric data, immune and antioxidant systems, and energetic status). Two of these constraints were linked to caging: starvation and fish density in cages, and one in relation to the post-caging handling: a short transport. Three in situ experiments were conducted with three-spined sticklebacks (Gasterosteus aculeatus). The first experiment compared the effects of three densities (low, medium, and high). The second experiment compared effects of starvation in fish fed every two days with fish that were not fed. Finally comparisons between sticklebacks which have suffered a short car transport after caging and sticklebacks killed without preliminary transport were made. The lack of food had no effect on fish energetic reserves but negatively affected their condition index and their immune system. Transport and high density induced oxidative stress, defined as an overproduction of reactive oxygen species and a stimulation of the antioxidant system. These two constraints also harmed the leucocyte viability. In order not to have any impact on ecotoxicity biomarkers during in situ experiments, it is preferable to decrease fish density in cages, prevent transport before dissections, and feed fish when the caging lasts more than two weeks.

In situ effects of metal contamination from former uranium mining sites on the health of the three-spined stickleback (Gasterosteus aculeatus, L.)

“…The sticklebacks were not fed during the experiment, which could explain the decline. This result was also observed on sticklebacks unfed compared to sticklebacks which were fed every 2 days, during another experiment (Le Guernic et al 2016). Although there are differences with the freshwater fish, Kerambrun et al (2012) showed that K for juvenile turbots, Scophthalmus maximus, also decreased after 10 days of fasting.…”

“…In order to discriminate the possible effects of our caged-fish design and other constraints due to in situ exposure, other experiments were conducted and summarized in the article of Le Guernic et al (2016). This study showed that the fish density used in the present study (1.33 fish/L) is not likely to induce effects on the studied biomarkers.…”

“…The phagocytic values were quite low compared to those obtained on fish kept in the laboratory, not subjected to stress (13.9 ± 5.0 %, n = 50, data not shown). Decreases of phagocytosis percentage between D14 and D28 observed for sticklebacks caged in the Malessard and Jonchère-SaintMaurice Ponds were maybe due to caging stress (Le Guernic et al 2016). However, this pattern was not observed for sticklebacks caged in the highest contaminated pond (Pontabrier).…”

“…Caging involves many sources of stress, such as lack of food, manipulation, transportation, and high fish density (Le Guernic et al 2016;Oikari 2006). Stress caused by these factors is indicated by enhancement of plasmatic cortisol levels (Blom et al 2000;Vazzana et al 2002).…”

“…Stress caused by these factors is indicated by enhancement of plasmatic cortisol levels (Blom et al 2000;Vazzana et al 2002). Some stressors can alter the antioxidant system (Blom et al 2000;Le Guernic et al 2016), decrease ROS production or modify the Ly distribution (Espelid et al 1996;Vazzana et al 2002). More serious effects, such as immunosuppression effects, resulting in decreased pathogenic resistance, also are possible (Bonga 1997;Espelid et al 1996).…”