Hydrobiologia 491: 321–330, 2003. E. van Donk, M. Boersma & P. Spaak (eds), Recent Developments in Fundamental and Applied Plankton Research. © 2003 Kluwer Academic Publishers. Printed in the Netherlands. 321 Sub-fossils of cladocerans in the surface sediment of 135 lakes as proxies for community structure of zooplankton, fish abundance and lake temperature Erik Jeppesen 1,4 , Jens Peder Jensen 1 , Torben L. Lauridsen 1 , Susanne L. Amsinck 1 , Kirsten Christoffersen 2 , Martin Søndergaard 1 & Stuart F. Mitchell 3† 1 Department of Freshwater Ecology, National Environmental Research Institute, Vejlsøvej 25, DK-8600 Silkeborg, Denmark 2 Freshwater Biological Laboratory, University of Copenhagen, Helsingørsgade 51, DK-3400 Hillerød, Denmark 3 Department of Zoology, University of Otago, P.O. Box 56, Dunedin, New Zealand 4 Dept. of Botanical Ecology, University of Aarhus, Nordlandsvej 63, DK-8230 Risskov, Denmark E-mail: ej@dmu.dk Received 7 August 2001; in revised form 6 May 2002; accepted 13 August 2002 Key words: zooplankton, surface sediment, zooplankton remains Abstract To elucidate the possibilities of using zooplankton remains in the surface sediment to describe present-days community structure and population dynamics of zooplankton, fish abundance and temperature, we compared contemporary data sampled in the pelagial during summer with the sediment record from the upper 1 cm of the sediment in 135 lakes covering a latitude gradient from Greenland in the north to New Zealand in the south. The abundance of three genera Bosmina, Daphnia and Ceriodaphnia of the total pool of ephippia was significantly related to the total abundance of the same taxa in the pelagic zone. However, in most lakes the abundance of Ceriodaphnia was higher in the sediment than in the water, which may be attributed to the overall preference by this genus for the littoral habitat. Using contemporary data from 27 Danish lakes sampled fortnightly during summer for 10 years, we found substantial inter-annual variations in the abundance of Daphnia spp., Ceriodaphnia spp., B. longirostris and B. coregoni. Yet, the sediment record mimicked the medium level well for most of the lakes, which suggests that the sediment record provides an integrated picture of the pelagic cladoceran community, which otherwise can be obtained only by long-term frequent contemporary sampling for several years. The contribution of Daphnia to the sum of Daphnia and Bosmina ephippia was negatively correlated with the abundance of fish expressed as catch per night in multi-mesh sized gill nets (CPUE). Yet, region-specific differences occurred, which partly could be eliminated by including nutrient state expressed as total phosphorus (TP) in a multiple regression. The average ratio of ephippia to the sum of ephippia and carapaces of Bosmina varied 40-fold between the sampling regions and was significantly negatively related to summer mean air temperature, and for Danish lakes also, albeit weakly, to fish CPUE but not to chlorophyll a. Apparently, temperature is the most important factor determining the ratio of parthenogenetic to ephippia producing specimens of Bosmina. We conclude that the sediment record of cladocerans is a useful indicator of community structure of pelagic cladocerans and the abundance of fish and temperature. Introduction Zooplankton community structure and dynamics vary significantly with changes in environmental variables, † Deceased. such as eutrophication and acidification, and with al- terations in fish community structure and abundance (Gliwicz, 1969; Patalas, 1972; Pace, 1986; Gulati, 1990; Hansson et al., 1998; Jeppesen et al., 2000a). In addition, the zooplankton community varies on both a spatial (vertical and horizontal) and a tem-