Abstract
Most of the commercial species of teleost fish spawn pelagic eggs. The distribution and horizontal and vertical transport of fish eggs depend on their placement in the water layers and it is a key factor for the recruitment of the class of the year of fish populations. The position in the water column depends mostly on the species-specific buoyancy of the eggs. If fish eggs precipitate at unsuitable depths, the larvae may find unfavorable environmental conditions for survival (hypoxia and anoxia). The increased concentration of inorganic particles in the water column due to submarine tailings disposal (STD) could alter the buoyancy properties of the fish eggs. In this study, the impact of calcium carbonate particles deriving from a Norwegian STD site on the buoyancy of eggs of two economically and ecologically important fish species, cod (Gadhus morhua) and haddock (Melanogrammus aeglefinus) was investigated. The eggs were exposed to three different concentrations of tailing particles for 48 hours, followed by a recovery period of 48 hours. Results show that the adhesion of inorganic calcium carbonate particles to the surface of the eggs significantly alters their specific gravity causing the precipitation of the eggs at medium and high concentrations of tailings and reduction of the buoyancy in low concentrations in comparison with controls. These results indicate that submarine tailings disposal in coastal waters and specifically in fjord’s ecosystems could alter the distribution of haddock and cod eggs in the water column and thus impact local fish populations recruitment.