|Physical and biological factors influencing the seasonal variation in distribution of zooplankton across the shelf at Nordvestbanken, northern Norway|
Halvorsen, E.; Tande, K.S. (1999). Physical and biological factors influencing the seasonal variation in distribution of zooplankton across the shelf at Nordvestbanken, northern Norway. Sarsia 84: 279-292
In: Sarsia. University of Bergen. Universitetsforlaget: Bergen. ISSN 0036-4827, more
|Authors|| || Top |
- Halvorsen, E.
- Tande, K.S.
This paper presents data on species composition, abundance, horizontal and vertical distributions of zooplankton from selected sites across Nordvestbanken, northern Norway, sampled monthly from March to September 1994.The sampling covered three stations: A (closest to shore), C and D (close to the shelf break). There was a distinct succession in species composition over the season, with shift from community almost entirely dominated by Calanus finmarchicus in May, towards a larger contribution of smaller, neritic species in August and September. Numerically C. finmarchicus made up about 70 %of the total zooplankton stock at stations D and C in May (about 90 %if nauplii, which mostly belonged to this species, (are included), whereas the proportion of this species was about 50 % at station A this month. The population development of the most common species agreed with earlier findings in the area. A CCA analysis was performed including total of 18 copepod species and 8 environmental variables. The pattern found demonstrated an inshore-offshore community gradient correlated to temperature, salinity and distance to shore. The most abundant copepod species at Nordvestbanken constituted a group which showed little or no correlation with either of the environmental variables included in the CCA analysis. These species are probably present in the area through- out the season, and are breeding successfully on the shelf. Temora longicornis, Acartia longiremis, and Paracalanus parvus represent the more neritic, shallow water, autumn species, and their presence is probably related to the offshore extension of the coastal water during summer. A third group composed of deep-water species such as Heterorhabdus norvegicus, Chiridius armatus, Scolecitricella minor and Pleuromamma robustacould also be distinguished, most likely introduced to the outer shelf area by events of intrusion of deeper slope water.