Atlantic cod, Gadus morhua L., larvae were fed rotifers, Brachionus plicatilis and Artemia franciscana enriched on four different commercial media, using the manufacturers' protocols. Pooled samples of 20 cod larvae were homogenized, diluted, and plated out on Petri dishes. The number of colony-forming units per larva was estimated, and the dominant strains subsequently sampled for sequencing of 16S rDNA. Bacteria showing high sequence similarity to a pathogen characteristic of cod and other fish species, Listonella anguillarum, were present in all four groups. Other taxa present among the dominating bacterial colonies were Pseudoalteromonas sp., and Vibrio sp. However, these bacteria could be assigned to genera only. The different enrichments probably affected the number of colony-forming bacteria per millilitre in the enrichment cultures as well as in the larval gastrointestinal (GI) tract. Also, the composition of the microbiota associated with the larval GI tract was probably affected by the enrichment media.

–  In several carotenoids‐based ornamented species, females invest carotenoids also into their gametes to increase the quality of the rapidly growing zygote. The extra carotenoids demand may cause females to trade‐off valuable carotenoids between ornament and eggs. This may be one reason why females are less showy ornamented than males. In our study‐population of Arctic charr, individuals of both sexes vary in degree of conspicuousness of their red abdomen and fins. None of the two carotenoids‐based ornaments was significantly associated with either (i) the amount of carotenoids in the egg, although being negative and close to significance, or (ii) potential condition‐dependent parameters like relative density of leucocytes, condition‐factor and parasitism. This study does not support the ‘direct selection hypothesis’ to explain the existence of female ornaments, and gives equivocal support for the hypothesis of asymmetrical investment of carotenoids into gametes to explain the less showy ornaments in females when compared with males.

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