The effect on species diversity by water current Controlled - PowerPoint PPT Presentation

The effect on species diversity by water current

Controlled Variables Water depth River bed substrate composition Light intensity Abundance of water plants Temperature

Dependent variable Animal species Ind Rate of water flow

Hypothesis Current has direct effect on the distribution of organisms.The biodiversity may be inversion related to the speed of the water current

Materials and methods • Light meter: measure the light intensity • Digital thermometer: measure the temperature • Forceps: pick out the species attached to the surfaces • Water flow meter: measure the speed of the water flow

Materials and methods • Tray: temporarily hold the species for investigation • Brush pen: discard the species onto the tray • Metal sieve: catch the species which are difficult to catch by using forceps flowing with the water current. • Meter: measure water depth

Method to control the variables • Measure one-by-one by using the apparatus. Carry out experiment at regions with same water depth, river bed substrate, light intensity, temperature and abundance of water plants.

Methods of measuring water flow rate • Using water flow meter to measure the water flow rate at the shallow and stony part of the stream where we did animal survey. Make a few measurements at different points and then take average of the readings.

Method to record the data of dependent variables • Using quadrant sampling method to find out animal species.

Experiments • Fair test • Temperature: 22.5 Degree Celsius • Water depth: 8cm • Light intensity: 9920 • Substrate: by observation

Results (1) • Water flow rate: 0.16m/s • Species in different sizes are present, ranging from 1mm to 2cm • Greater abundance of species in smaller size • E.g. Dragonfly nymph, small stream leech, mayfly nymph, bloodworm, water penny

Results(2) • Water flow rate: 0.21m/s • Absence of species in large size • Presence of species in smaller size, particularly Caddisfly larva attached to the rock surfaces • E.g. Caddisfly larva, large stream snail

Results(3) • Water flow:0m/s • Presence of species in different sizes, ranging from 1mm to 5cm • E.g. Canton bee shrimp, toothed bee shrimp, large stream snoil, Toby

Analysis • Species smaller in size are present in both high and low water current.

Analysis • Species which are greater in size are present in lower water current, while absent in greater water current.

Analysis • Species in greater size may need to overcome a greater fluid resistance. It may be more difficult for them to maintain stability. • Certain species may have special adaptations like shells to protect them from high pressure. • Food may be washed away by the high water current

Summary • Clemency favors the growth and development of the species perhaps due to malnutrition and instability • Species with adaptations may have greater possibilities to survive in malevolence per