Lake Pusiano field experiment: first preliminary results

Greg Attwater & Diego Copetti, Supervisors: Giannni Tartari & Jorg Imberger

PART 1: CWR Equipment

SCAMPMeasures extremely small scale fluctuations (few mm) in temperature and conductivity (Carter & Imberger, 1986)

by Greg Attwater

Lake Diagnostic System (LDS)LDS combine a weather station measuring wind, air temperature, relative humidity, short wave radiation and net long wave radiation with a thermistor chain . Using the LAKEMON software, the system is used to monitor the strength of mixing activity in a water body by using Lake Number concept. Robertson & Imberger (1984).

F-ProbeA fine scale profiler using commercially available sensors for the measurement of temperature, conductivity, oxygen, pH and turbidity (Fozdar et al., 1985)In this experiment the F-Probe has been dropped with the Fluoro probe in order to obtain information on the distribution of 4 algal groups, total clorophyll a and DOC.

Why?

Scientific goals: to investigate on the bluegreen – green algal shift between 2002 and 2003;

to study the mechanism involved in the formation of the plankton patches. Distinguishing between physical, chemical and biological causes;

Applied goal: to study the ecology of the Lake Pusiano during the stratification period in order to obtain a detailed description of the nutrients circulation and their effect on the phytoplankton populationand suggest adequate strategies in order to obtain an ecological recover of the lake.

Part 2: Scientific Issues

by Diego Copetti

LDSmeteorological parameters

thermal structure

SCAMPwater column stability

F-ProbeTransport process

WQ samplingnutrient availability

Biological response

Biological sampling Fluoro probePhosphorus bioavailable

experiment

PAR

Experimental plan

LDS

SCAMP

hydrochemical parameters:P6, P18, P21biological parametersP3, P19, P11, P15, P21PARP3, P6, P21, P11, P15, P16, P18, P20

Bioavailable phosphorus concentration experiment

WE transect

NS transect

ELCOM - CAEDYM

Results: meteorological data and thermal structure

During 25 July 2003 intense wind produce regular high frequency wave

SCAMP profile 209 day

2002 hydrodynamic model (DYRESM)

The data collected during the Pusiano field experiment 2003 appear very consistent;

The first elaborations of the physical dataset underline the production of regularhigh frequency internal wave;

It is evident an anisotropy distribution of the phytoplankton community aggregatedin patches;

The results obtained during the field experiment will be the starting point of the restoration plan of the lake, particularly in the evaluation of the nutrient internalload.

Conclusion