Sunniva Lönning

The early development of the halibut, Hippoglossus hippoglossus (L.), compared with other marine teleosts

Eggs were artificially fertilized and incubated in seawater of various salinities and temperatures. Both the ultrastructure of the exceptionally large eggs (average diameter: 2.92 mm) and the embryonic development suggest that the early developmental stages of the halibut are pelagic. Light and electron microscope studies of the halibut eggs showed a thin, homogeneous, lamellated chorion with small pores on the outer surface. However, neutral buoyancy determinations indicated that eggs would float only in salinities greater than c. 37 ‰. The halibut embryo, which develops very slowly, hatches at an apparently premature stage.

Reproductive cycles of two closely related sea urchin species, Strongylocentrotus droebachiensis (O.F. Müller) and Strongylocentrotus pallidus (G.O. Sars)

Strongylocentrotus droebachiensis and S. pallidus, from c. 70° N in the north east Atlantic, have different spawning times. The main breeding season of S. droebachiensis was found to be late winter, while S. pallidus spawned during spring or early summer. This difference in spawning time may explain why hybridization is rare at these latitudes. Both species initiated rapid oocyte growth during autumn. Maturing and mature specimens of S. pallidus were found during a longer period than those of S. droebachiensis. Ovaries did not display a resting phase. Oocyte proliferation and differentiation was initiated during winter and spring while the previous generation of mature eggs was still present. Gonad indices and gonad weights of maturing and mature S. pallidus were always lower than those of S. droebachiensis, which may suggest a lower fecundity in the former.

Morphological and experimental studies on the genus Echinus

Abstract The biological variation in the population of the genus Echinus from the vicinity of Bergen was studied. The morphological characters previously used in distinguishing between the species were discussed and new species-specific characters were established. The number of adult hybrid animals was found to be considerable. An experimental investigation of fertilization, cross fertilization and development in the genus Echinus was performed.

The effects of Esso Corexit 9527 on the fertilizing capacity of spermatozoa

Abstract The water-soluble oil dispersant Esso Corexit 9527 has earlier been found to interfere, even in low concentrations, with fertilization and development. Further studies of the effect on sea urchin spermatozoa demonstrate that Corexit 9527 gives negative biological effects in concentrations down to 0.0003 ppm.

On the formation of short-lived, toxic, water-soluble compounds during illumination of crude oil on seawater

Abstract The toxicity of various oil extracts has been studied using cod eggs as test organisms. The most toxic effect was observed when the eggs were kept underneath the water/oil interface during irradiation. This supports the notion that toxic primary photoproducts with a short life-time are generated when oil on seawater is illuminated.

Scanning electron microscope studies of the surface of the sea urchin egg.

SummaryThe surface of the egg of the two sea urchin species,Strongylocentrotus droebachiensis andS. pallidus, was studied with SEM. Clear differences were observed between the two species, in both the number and form of the microvilli. The changes in the egg surface which follow insemination are described.

Deleterious effects of corexit 9527 on fertilization and development

Abstract The effect of the water soluble oil dispersant Corexit 9527 was tested on larvae from several species of sea urchins and marine fishes. Severe effects in fertilization and development were registered often resulting in pathological larvae and rapid cytolysis. The combination of Corexit 9527 with oil was found to be even more dangerous to the embryo than Corexit or oil alone.

Observations on the chromaffin granules of the ventricle and the portal vein heart of Myxine glutinosa L.

Abstract The chromaffin granules present in the ventricle and the portal vein heart of the hagfish, Myxine glutinosa L., have been studied by electron microscopy, using for fixation a glutaraldehyde method which allows to distinguish between granules carrying either adrenaline or noradrenaline. From sections of fresh tissues as well as from particle fractions prepared by centrifugation of sucrose homogenates of the two hearts, pictures were obtained which confirm the presence of adrenaline in the granule-rich cells in the ventricle and of noradrenaline in the portal vein heart. Attention was also directed to granules, already noted by other observers, that occur in the myocardial cells adjoining the chromaffin cells. It was noted that both in the ventricle and in the portal vein heart these myocardial granules looked moderately electron dense, like adrenaline granules. Possible interpretations of these observations are discussed.

Toxicity and chemical reactivity of naphthalene and methylnaphthalenes

Abstract Newly fertilized sea urchin and fish eggs were exposed to solutions of naphthalene and mono- and disubstituted methylnaphthalenes. The toxic effects were not dependent on the number of methyl groups alone, but rather on their specific ring positions. Comparison with calculated atom and bond reactivity indices indicates that the variation in toxicity is related to differences in electronic properties of the molecules. The results are in favour of an initial atom oriented interaction mechanism of toxicity.

Toxic effects of hydroxylated aromatic hydrocarbons on marine embryos

Abstract Phenol and methyl-substituted phenols were acutely toxic towards sea-urchin and fish eggs in concentrations of 3–30 ppm. Naphthols were considerably more toxic than phenols, killing most embryos even in concentrations of 0.3–3 ppm. Sublethal concentrations of phenols and naphthols caused pigment defects in cod larvae.