Factors influencing the distribution of nereid polychaetes in Danish coastal waters
In: Ophelia: International Journal of Marine Biology. Ophelia Publications: Helsingør. ISSN 0078-5326, more
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| Abstract |
Evidence from field data (Norsminde Fjord and Vellerup Vig, Denmark) suggested that low salinity limits the landward distribution of the nereid polychaetes Nereis virens and N. succinea into estuaries and fjords. N. diversicolor; on the other hand, is usually confined to the low salinity areas. Laboratory tank-experiments indicated that competition in the form of interspecific aggressions are the primary determinant for the distribution in high salinity areas. Aggressiveness increases in the sequence: N. diversicolor; N. virens and N. succinea. However, the former species appears to be harmed more by N. virens than by N. succinea. The observed exclusion of N. diversicolorin areas occupied by N. succinea may therefore be caused be diffuse competition, i.e. cumulative effects of N. virens and N. succinea. N. diversicolor has apparently evolved a high tolerance for extreme environments at the expense of competitive ability. The tank-experiments revealed a clear preference for specific sediment types, i.e. N. virens-organic poor sand; N. succinea and N. dioersicolor-organic rich silts. However, the observed similarity of nereid distribution combined with the dissimilarity in sediment organic content in the two study areas indicated that sediment preference is not the primary determinant for the distribution patterns. |
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