Composition, Abundance and Population Structure of Spring-Time
Zooplankton in the Shelf-Zone of Laptev Sea
KN. Abramova
Lena-Delta State Reserve, 28 Fiodorova St., 678400 Tiksi, Yakutia, Russia
Received I May 1997 and accepted in revised form 9 February 1998
Abstract - New evidence was received concerning the composition, distribution and
abundance of zooplankton in May-June 1996 in the shelf area of Laptev Sea. The minimal
depth of area is 6 m, the maximum 33 m. As measured at various stations, ice thickness
ranges between 1.20 and 2.07 m. Species diversity of spring-time zooplankton is
represented by 23 taxa of marine, brackishwater and freshwater species. Average abundance
of zooplankton across the examined area in May amounted to 155 individuals per m3 From
records of most stations, brackishwater plankton (mass species Drepanopus bungei) was
predominantly abundant, being at the time in the stage of reproduction. Induced by spring
flood, variations in hydrologic conditions in June have resulted in quantitative and
qualitative changes in zooplankton community. Brief analysis of the population structure
and development biology of some mass species in the shelf zone of Laptev Sea was made
on the basis of previous and newly obtained data.
Introduction
Previous investigations were effective to accumulate in the literature a sufficiently
comprehensive evidence on summer-time zooplankton of the shelf area of Laptev Sea. Species
composition, distribution, quantitative parameters characterizing plankton organisms are
comparatively well understood ecological aspects of plankton existence are touched upon.
However, knowledge of the structure and functioning of zooplankton community in the shelf
area of Laptev Sea in extended winter periods is insufficient numbering only several papers
(Pirozhnikov, 1958; Lutsik et aI., 1981; Abramova, 1996) with complete lack of evidence on
interSeasonal and annual dynamics of zooplankton in Laptev Sea. Thus, mostly intriguing is
the evidence concerning behavior of pelagic communities under ice cover. The results received
by joint Russian-German expedition Transdrift-IV between 16 May and 16 June 1996 proved
useful to permit to somewhat close the information gap.
Material and methods
In the total, the spring expedition of 1996 collected 44 zooplankton samples from 24 stations
located in 3 transects: one vertical and two horizontal (Figure I). One-time sampling at all the
stations was made prior to spring flood (between 18.05 and 29.05); after the beginning of the
flood (3.06 - 12.06) the second sampling was made twice at stations 3-6, 8-11 and once at st.
20, 21, 23 and 24. Complete sampling was made using small Jeddy net (hole input diameter
0.17 m, seive mesh 86!lm). At each stations nets were dipped three times permitting to receive
a representative sample. Arrangement of depths, temperatures and salinity at each station in
May is summarized in Table 1. After June 10, positive temperatures bellow 1 DC were recorded
on the southern stations of surface horizon of vertical transect of and along the whole water
column at shallow water stations. With the increase of freshwater runoff in June, evident
salinity reduction was reported across the whole of the observation area with the exception of
station 21 where near surface salinity was reported to increase to 37%0 and near bottom salinity
to 38. Mass species development biology was studied with attraction of the previous evidence
In: Kassens, H., H.A. Bauch, I. Dmitrenko, H. Eicken, H.-W. Hubberten, M. Melles, J. Thiede and L. Timokhoy (eds.)
Land-Ocean Systems in the Siberian Arctic: Dynamics and History. Springer-Verlag, Berlin, 1999, 161-168.
Zooplankton in the Shelf-Zone of Laptev Sea
KN. Abramova
Lena-Delta State Reserve, 28 Fiodorova St., 678400 Tiksi, Yakutia, Russia
Received I May 1997 and accepted in revised form 9 February 1998
Abstract - New evidence was received concerning the composition, distribution and
abundance of zooplankton in May-June 1996 in the shelf area of Laptev Sea. The minimal
depth of area is 6 m, the maximum 33 m. As measured at various stations, ice thickness
ranges between 1.20 and 2.07 m. Species diversity of spring-time zooplankton is
represented by 23 taxa of marine, brackishwater and freshwater species. Average abundance
of zooplankton across the examined area in May amounted to 155 individuals per m3 From
records of most stations, brackishwater plankton (mass species Drepanopus bungei) was
predominantly abundant, being at the time in the stage of reproduction. Induced by spring
flood, variations in hydrologic conditions in June have resulted in quantitative and
qualitative changes in zooplankton community. Brief analysis of the population structure
and development biology of some mass species in the shelf zone of Laptev Sea was made
on the basis of previous and newly obtained data.
Introduction
Previous investigations were effective to accumulate in the literature a sufficiently
comprehensive evidence on summer-time zooplankton of the shelf area of Laptev Sea. Species
composition, distribution, quantitative parameters characterizing plankton organisms are
comparatively well understood ecological aspects of plankton existence are touched upon.
However, knowledge of the structure and functioning of zooplankton community in the shelf
area of Laptev Sea in extended winter periods is insufficient numbering only several papers
(Pirozhnikov, 1958; Lutsik et aI., 1981; Abramova, 1996) with complete lack of evidence on
interSeasonal and annual dynamics of zooplankton in Laptev Sea. Thus, mostly intriguing is
the evidence concerning behavior of pelagic communities under ice cover. The results received
by joint Russian-German expedition Transdrift-IV between 16 May and 16 June 1996 proved
useful to permit to somewhat close the information gap.
Material and methods
In the total, the spring expedition of 1996 collected 44 zooplankton samples from 24 stations
located in 3 transects: one vertical and two horizontal (Figure I). One-time sampling at all the
stations was made prior to spring flood (between 18.05 and 29.05); after the beginning of the
flood (3.06 - 12.06) the second sampling was made twice at stations 3-6, 8-11 and once at st.
20, 21, 23 and 24. Complete sampling was made using small Jeddy net (hole input diameter
0.17 m, seive mesh 86!lm). At each stations nets were dipped three times permitting to receive
a representative sample. Arrangement of depths, temperatures and salinity at each station in
May is summarized in Table 1. After June 10, positive temperatures bellow 1 DC were recorded
on the southern stations of surface horizon of vertical transect of and along the whole water
column at shallow water stations. With the increase of freshwater runoff in June, evident
salinity reduction was reported across the whole of the observation area with the exception of
station 21 where near surface salinity was reported to increase to 37%0 and near bottom salinity
to 38. Mass species development biology was studied with attraction of the previous evidence
In: Kassens, H., H.A. Bauch, I. Dmitrenko, H. Eicken, H.-W. Hubberten, M. Melles, J. Thiede and L. Timokhoy (eds.)
Land-Ocean Systems in the Siberian Arctic: Dynamics and History. Springer-Verlag, Berlin, 1999, 161-168.