… with a trend of improving trophic status. … with a trend of improving trophic status.

0

10

20

30

40

1/1/94 1/1/98 1/1/02 1/1/06

Inflow (757 r. km)Inflow (757 r. km)

mg chl a m-3mg chl a m-3

0

100

200

300

400

1/1/83 1/1/87 1/1/91 1/1/95 1/1/99 1/1/03 1/1/07

Outflow (163 r. km)Outflow (163 r. km)

mg chl a m-3mg chl a m-3

An order of magnitudeincrease in 1-2 weeks.An order of magnitudeincrease in 1-2 weeks.

Factors potentially contributing to the increase in algal biomass

Factors potentially contributing to the increase in algal biomass

- Altered flow pattern (flood protection, storage)

- Nutrient loads (sewage & diffuse agricultural)

- Polluted tributaries

- Hypertrophic oxbow lakes

- Inshore retention zones

Aims of the study

- To assess the relative importance of various factors in phytoplankton dynamics by using highresolution longitudinal data and hydrodynamicalmodeling.

- To test the applicability of automatic measuring devices (DF spectroscope, light scattering sensors)used with success in Lake Balaton for monitoring running waters.

Presentation structure

- Data collection.

- Hydrodynamical modeling (Kozma & Koncsos).

- Comparison of manual and automatic measurements.

- Primary data analysis.

- Phytoplankton dynamics (Honti et al.).

( - Nutrient retention (Kovács et al.).)

Measurements: 17 to 21 July 2006 downstream 22 to 26 July 2006 upstream

Measurements: 17 to 21 July 2006 downstream 22 to 26 July 2006 upstream

No measurements during the nights. No measurements during the nights.

0

100

200

300

400

500

0 8 16 24 32

TiszaSzamosMaros

m3 s-1