Wednesday, June 11, 2008

Study of plankton

During World Environment Week, Year 6 students went on a Grime Scene Investigation to Georges River. During a river cruise, water samples were collected for studying under a microscope back at base.

We learnt that plankton is the start of the foodchain in the marine environment. The water samples we gathered were studied under a microscope and projected onto a screen for all to see. Unfortunately, in all the samples studied only one type of zooplankton (animal) was found in amongst the phytoplankton (plant). This was compared to a chart and determined to be Veliger (larva of the limpet) [image 1 below].

DVD footage of previous zooplankton finds was then screened and students identified those from the charts as well.

Activity - Click on the images below to view large versions of the charts and use them to identify the zooplankton in images 2, 3 and 4 above.

Answers: 2=m (second chart) 3=b (second chart) 4=f (first chart)

Why is plankton important to marine food chains? Because it is the starting point. Without it, there would be nothing for fish to eat; without fish there would be nothing for water birds to eat.

Fish dissection

During World Environment Week, Year 6 students went on a Grime Scene Investigation to Georges River.

A very popular part of the day involved disecting fish!

Tuesday, June 10, 2008

Grime Scene Investigation

On a particularly grim and grey June day in 2008, nine Year 6 students attended a Grime Scene Investigation on the Georges River. The day started with a river cruise looking at activities around the River's edge and the impacts of these on the water. Historically the main post-European river activity was oyster farming.

The following diagram (representing the same area as the aerial photo above) had locations A to H marked and, listening to the commentary, students had to identify the types of landuse activities from the key below.

KEY: 1 = factories/industry 2 = residential (housing) 3 = water sports/clubs 4 = open spaces /parks 5 = natural vegetation 6 = boat moorings 7 = landing ramp/wharf

Answers: A=4, 7 B=6 C=4 D=2 E=2, 4, 7 F=1 G=5 H=3

We learnt:
- that there are 235 different organisms in the water!
- that sea grass is the estuary supermarket being home to many of these organisms.
- that the catchment area for George's River is 960 square kilometres (which is a lot of stormwater run off)
- there is a 50km stretch of saltwater before the weir at Liverpool

Environmental issues include:
- stormwater drains emptying into the river, many without gross pollutant traps (GPTs)
- unnatural edges around most of the Bay prevent saltmarsh plants and mangroves from growing
- pollution from sewerage leaks, chemicals from boat washing get into the river
- Kogarah Council collected 113 tonnes of litter from one GPT in one year!
- litter from waterside picnic areas (particularly plastic bags which are eaten by birds mistaking them for jellyfish)

Environment solutions include:
- the use of boom nets to contain pollution (for eg at waterside building sites)
- installation of more GPTs
- fines for polluting practices
- establishment of "no wash" zones (eg Sylvania Waters)

During the cruise, water samples were taken for studying back at base.

See Study of Plankton for the results.

See also Fish dissection.

The excursion required certain roles to be played by the students. They were:
water quality chemist
environmental scientist

to be continued...