The population dynamics, reproductive biology and geographic distribution of Boreomysis nobilis G.O.Sars 1879 in coastal fjords of Newfoundland, Canada

Clark, Kirsten Jane (1992) The population dynamics, reproductive biology and geographic distribution of Boreomysis nobilis G.O.Sars 1879 in coastal fjords of Newfoundland, Canada. Masters thesis, Memorial University of Newfoundland.

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Abstract

The hyperbenthic mysid, Boreomysis nobilis G.O. Sars 1879, is reported from nine new locations around the island of Newfoundland in eastern Canada. It is most common within and at the mouths of deep fjords and is less common or absent outside these fjords. Its absence from two bays where the depths, temperatures and salinities are all within the range inhabited by B. nobilis in other bays indicates that other factors are likely influencing local distribution patterns. -- Boreomysis nobilis breeds throughout the year, since all developmental stages were present on all sampling dates. However, there is a period of increased breeding activity in the late spring and early summer. An examination of the relationship between brood size, body volume of ovigerous females, and number of stage 1 larvae (eggs) indicates that B. nobilis produces a smaller number of larger eggs than is predicted by the regression calculated for epipelagic and coastal mysids by Mauchline (1980). This agrees with the conclusion of Wittmann (1984) for epipelagic cold-water species of mysids. Thus B. nobilis exhibits a more K-selected strategy than its epipelagic counterparts from warmer water. -- The catch rates for B. nobilis are highest in the deep water within 150m of the bottom. However, no differences are found in the vertical distribution of the different life history stages of B. nobilis and no evidence is found for large-scale diel vertical migrations. -- The parasite Thalassomyces boschmai (Nouvel 1954) is reported from B. nobilis and from Newfoundland waters for the first time. Its localized distribution in two bays is suggested to be a result of the restricted geographic distribution pattern of its host.

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