Bjørn Berland

Bio: Bjørn Berland is an academic researcher from Directorate of Fisheries. The author has contributed to research in topics: Ommatokoita & Cystophora cristata. The author has an hindex of 3, co-authored 4 publications receiving 401 citations.

Nematodes from some Norwegian marine fishes

Abstract: The present paper deals with nematode parasites from some Norwegian marine fishes. The major part of the material was collected personally from fishes caught in the fjords near Bergen and Tromso; the minor part of the material was obtained from the zoological museums in Oslo and Bergen and from other sources. 260 specimens of fish, belonging to 64 species, have been searched for nematode parasites. 9 species of fish were found to be free of nematodes.

Copepod Ommatokoita elongata (Grant) in the Eyes of the Greenland Shark—a Possible Cause of Mutual Dependence

Abstract: IN July 19591, and in July–August 1960, I had the opportunity to take part in Greenland shark fishery with Norwegian commercial sealing vessels in east Greenland waters. Data on this shark were collected, supplemented with information received from experienced Greenland shark fishermen.

Use of glacial acetic acid for killing parasitic nematodes for collection purposes.

Abstract: MANY parasitic nematodes have a tendency to coil considerably when placed in water or cold-fixing fluids such as alcohol or formalin. Ideally, in order to facilitate the subsequent microscopic examination, nematodes should die in an extended position. This is best achieved by the use of 70 per cent alcohol or Looss' fluid (9 parts 70 per cent alcohol and 1 part glycerol), near boiling temperature, in which nematodes uncoil and become fixed rapidly. However, hot alcohol is rarely available during field work, and a simple alternative method for killing and fixing nematodes in an extended position is likely to be desired by other workers.

The Hood of the Hooded Seal, Cystophora cristata Erxl.

Abstract: IT is well known that the male of the hooded seal, Cystophora cristata, can inflate its hood, which is the greatly enlarged skin of the snout. It is also known that the male hooded seal can extrude an assumed pair of fiery red bladders or balloons through his nose. The presence in the nose of two evertible cœca, which would apparently be turned inside out in much the same way as glove-fingers, was claimed by Mohr1 from the study of a museum specimen.

Advances and trends in the molecular systematics of anisakid nematodes, with implications for their evolutionary ecology and host-parasite co-evolutionary processes.

Abstract: The application of molecular systematics to the anisakid nematodes of the genera Anisakis, Pseudoterranova and Contracaecum, parasites of aquatic organisms, over the last two decades, has advanced the understanding of their systematics, taxonomy, ecology and phylogeny substantially Here the results of this effort on this group of species from the early genetic works to the current status of their revised taxonomy, ecology and evolutionary aspects are reviewed for each of three parasitic groups It has been shown that many anisakid morphospecies of Anisakis, Contracaecum and Pseudoterranova include a certain number of sibling species Molecular genetic markers provided a rapid, precise means to screen and identify several species that serve as definitive and intermediate and or/paratenic hosts of the so far genetically characterized species Patterns of differential distribution of anisakid nematodes in various definitive and intermediate hosts are presented Differences in the life history of related species can be due both to differential host-parasite co-adaptation and co-evolution, and/or to interspecific competition, that can reduce the range of potential hosts in sympatric conditions Phylogenetic hypotheses attempted for anisakid nematodes and the possible evolutionary scenarios that have been proposed inferred from molecular data, also with respect to the phylogeny of their hosts are presented for the parasite-host associations Anisakis-cetaceans and Contracaecum-pinnipeds, showing that codivergence and host-switching events could have accompanied the evolution of these groups of parasites Finally, examples in which anisakid nematodes recognized genetically at the species level in definitive and intermediate/paratenic hosts from various geographical areas of the Boreal and Austral regions and their infection levels have been used as biological indicators of fish stocks and food-web integrity in areas at high versus low levels of habitat disturbance (pollution, overfishing, by-catch) are presented

Ecology of marine parasites

Abstract: Important ecological aspects of marine parasites are discussed. Whereas effects of parasites on host individuals sometimes leading to death are known from many groups of parasites, effects on host populations have been studied much less. Mass mortalities have been observed mainly among hosts occurring in abnormally dense populations or after introduction of parasites by man. As a result of large-scale human activities, it becomes more and more difficult to observe effects of parasites on host populations under “natural” conditions. Particular emphasis is laid on ecological characteristics of parasites, such as host range and specificity, microhabitats, macrohabitats, food, life span, aggregated distribution, numbers and kinds of parasites, pathogenicity and mechanisms of reproduction and infection and on how such characteristics are affected by environment and hosts. It is stressed that host specificity indices which take frequency and/or intensity of infection into account, are a better measure of restriction of parasites to certain hosts than “host range” which simply is the number of host species found to be infected.

Anisakis and anisakiasis

Abstract: Publisher Summary This chapter reviews the literature on Anisakis, including use of the nematode as a biological tag in applied fishery science. The genetic diagnosis of Anisakis is presented as: three lips, each bearing a bilobed anterior projection, which carries the single dentigerous ridge; interlabia absent; excretory gland with duct opening between ventrolateral lips; oesophagus with anterior muscular portion (preventriculus) and posterior ventriculus, the latter being oblong and sometimes sigmoid or as broad as long; no oesophageal appendix or intestinal caecum; vulva in middle or first third of body; spicules of male unequal; preanal papillae numerous; postanal papillae including a group of three or four pairs set close to the tip of the tail on the ventral side. While euphausiids appear to be important crustacean hosts of Anisakis at least in offshore areas, further is required to show other crustaceans to be significant, possibly in inshore waters. Further investigation may show squid to be of greater significance in the transmission of Anisakis to final hosts than the literature indicates, bearing in mind the importance of squid in the diet of many cetacean species. Several aspects of development remain obscure. In view of the taxonomic importance of the “excretory system” in ascaridoid nematodes, its physiological functions are poorly understood; Anisakis may prove to be a useful experimental model for investigation of these functions. With regard to accidental infection of man with Anisakis, further study might be made of a possible allergic predisposition to severe gastrointestinal reaction.

Molecular systematics, phylogeny and ecology of anisakid nematodes of the genus Anisakis dujardin, 1845 : An update

Abstract: Advances in the taxonomy and ecological aspects concerning geographical distribution and hosts of the so far genetically recognised nine taxa of the nematodes belonging to genus Anisakis (i.e. A. pegreffii, A. simplex s.s., A. simplex C, A. typica, A. ziphidarum, Anisakis sp., A. physeteris, A. brevispiculata and A. paggiae) are here summarized. Genetic differentiation and phylogenetic relationships inferred from allozyme (20 enzyme-loci) and mitochondrial (sequences of cox-2 gene) markers, are revised and compared. The two genetic analyses are congruent in depicting their phylogenetic relationships. Two main clusters are showed to exist in the obtained trees, one encompassing the species A. pegreffii, A. simplex s.s., A. simplex C, A. typica, A. ziphidarum and Anisakis sp.; while, the second including A. physeteris, A. brevispiculata and A. paggiae. The existence of two clades is also supported by their morphological differentiation in adult and larval morphology. Comparison of phylogenetic relationships among Anisakis spp. with those currently available for their cetacean definitive hosts suggests parallelism between host and parasite phylogenetic tree topologies. Preliminary data for reconstruction of a possible co-evolutionary scenario between cetacean hosts and their Anisakis endoparasites suggests that cospeciation and host-switching events may have accompanied the evolution of this group of parasites. Finally, genetic/molecular markers for the identification of the so far genetically recognized taxa of Anisakis at any life-stage and both sexes were given also in relation to human anisakiosis is discussed.

Aspects of the life cycle and morphology of Hysterothylacium aduncum (Rudolphi, 1802) (Nematoda, Ascaridoidea, Anisakidae)

Abstract: Gravid Hysterothylacium aduncum from the intestine of eelpout, Zoarces viviparus, were used as the source of eggs for study. The two first moults occurred in the egg, which does not normally hatch ...