Phytoplankton and zooplankton (Cladocera, Copepoda) relationship in the eutrophicated River Danube (Danubialia Hungarica, CXI)

Abstract

The seasonal variation in primary production, individual numbers, and biomass of phyto-and zooplankton was studied in the River Danube in 1981 . The secondary production of two dominant zooplankton species (Bosmina longirostris and Acanthocyclops robustus) was also estimated . In the growing season (April-Sept .) individual numbers dry weights and chlorophyll a contents of phytoplankton ranged between 30-90 x 10 6 individuals, l -', 3-12 mg 1 -', and 50-170µg 1 -1 , respectively . Species of Thalassiosiraceae (Bacillariophyta) dominated in the phytoplankton with a subdominance of Chlorococcales in summer . Individual numbers and dry weights of crustacean zooplankton ranged between 1400-6500 individuals M-3 , and 1.2-12 mg m-3, respectively . The daily mean gross primary production was 970 mg C m-3 d -1 , and the net production was 660 mg C m-3 d -' . Acanthocyclops robustus populations produced 0 .2 mg C m-3 d -1 as an average, and Bosmina longirostris populations 0 .07 mg C m-3 d -'. The `ecological efficiency' between phytoplankton and crustacean zooplankton was 0 .03 % . M J J J A J A S S ----Bosmina longirostris

The phytoplankton community of the River Meuse, Belgium: seasonal dynamics (year 1992) and the possible incidence of zooplankton grazing

“…between 50 and 100 mg m-3 , reaching 200 mg m-3 (River Danube, Bothfr & Kiss, 1990), and even high-Comparison with other European rivers er values (Descy et al, 1988). The seasonal pattern of different groups of algae are also similar in these The Meuse phytoplankton exhibits great similarities rivers.…”

“…In addition biomass of phytoplankton are clearly discharge, light to the rivers identified by Descy (1987) as sharing and temperature. The prominent role of the hydrologsimilar plankton behaviour, we may cite: the River ical regime is well illustrated by comparison with the Danube (Kiss, 1984(Kiss, , 1986(Kiss, , 1987Steinberg et al, longitudinal pattern of plankton growth in the River 1987; Bother & Kiss, 1990), the River Moselle (Descy Rhine and the River Meuse: De Ruyter Van Steveninck & Willems, 1991;Descy, 1993), the River Neckar et al (1990b showed that the variations probably lie (Hepperle, unpublished), the River Rhine (Friedrich in differences in flow regime between both rivers. The & Viehweg, 1984; River Rhine, which is fed by rainwater and the melt-1990a, b), the River Severn (Reynolds & Glaister, ing of glaciers in the Alps, has a relatively constant 1993), the River Vils (Steinberg et al, 1987) and the discharge.…”

Temporal and spatial variation in zooplankton populations in the River Great Ouse: an ephemeral food resource for larval and juvenile fish

“…During droughts the normally low, summer discharges are reduced further by additional demands for water. Responses of plankton communities to the frequency and magnitude of changing river discharge have previously been described for various rivers; for example, Ferrari et al (1989) in relation to short time-scale variation in densities of planktonic rotifers in the River Po and Bothar and Kiss (1990) referring to the primary and secondary production in the Hungarian River Danube. A review of published information on riverine densities of zooplankton world-wide (Bottrell, 1977) indicated a wide range of recorded densities, with Rotifera dominating during periods of high densities during summer, when they are an important component of the food taken by young ®sh .…”

Effect of sampling effort and sampling frequency on the composition of the planktonic crustacean assemblage: a case study of the river Danube

“…The minimal sample size resulted in 1,000 and 300 l of water, respectively. This sample size is beyond those applied in the studies of riverine plankton: 10 l (Illyová 2006), 20 l (De Ruyter Van Steveninck et al 1990), 25 l (Vranovsky 1991), 30 l (Saunders and Lewis 1989), 40 l (Reckendorfer et al 1999), 50 l (Gulyás 1995), 60 l (Ietswaart et al 1999), 100 l (Gulyás 1994;Maria-Heleni et al 2000) and 200 l (V. Balogh et al 1994;Bothár 1988;Bothár and Kiss 1990). Obviously, taking 1,000 l of water would mean an enormous effort, and this should not be the desired goal.…”

“…Generally, seasonal dynamics of riverine zooplankton have been discussed on the basis of samples collected at biweekly (Kim and Joo 2000;Maria-Heleni et al 2000;Reckendorfer et al 1999) or weekly intervals (Bothár 1988;Bothár and Kiss 1990;V.-Balogh et al 1994). Bothár (1996) performed zooplankton investigations in the river Danube on the daily basis and pointed out that no regular quantitative change or fluctuation in zooplankton abundance can be observed, although phytoplankton and water chemical data showed regular daily patterns.…”