Analysis of Aquatic Lifeforms in Water Sample

Introduction to Experiment

Assessment of water body productivity and trophic status is based on the number and type of organisms present. Highly productive water bodies have a high density of phytoplankton, supporting various trophic levels due to nutrients and dissolved oxygen. Non-productive water bodies have low density and are transparent, with fewer trophic levels. Biological analysis of water samples can identify pollution levels, as some organisms can serve as strong indicators of water pollution.

Procedure of Experiment:

The living organisms in the sample are preserved by adding 5 mL of formaldehyde-acetic acid to 1 litre of water collected from nearby bodies.
Each sample is labelled and transferred to a laboratory.
When the samples are left undisturbed for 48–72 hours, concentrated sediment containing preserved organisms is obtained.
The sediment is dissolved in a small test tube and transferred to a slide.
After placing a coverslip, the slide is observed under a compound microscope.

Sample	List of organisms observed under a compound microscope
Pond water sample	Cyanobacteria: Anabaena, Calothrix, Spirulina, Rivularia, Oscillatoria, Gloeocapsa, Phormidium and Lyngbya.
Pond water sample	Phytoplanktons: Volvox, Chlamydomonas, Draparnaldiopsis, Euglena, Spirogyra, Closterium, Staurastrum, Gymnodinium, Ceratium, Peridinium, Amphora, Skeletonema, Nitella, Golenkinia, Pediastrum, Ankistrodesmus, Cryptomonas, Navicula, Biddulphia, Peridinium, Cosmarium, Desmidium and Coscinodiscus.
River water sample	Cyanobacteria: Nostoc, Microcystis, Gloeotrichia, Synechococcus, Synechocystis andCylindrospermum.
River water sample	Phytoplanktons: Coelastrum, Asterionella, Amphora, Mougeotia, Hydrodictyon, Chlorella, Scenedesmus, Melosira, Nitzschia, Gomphonema, Cocconeis, Stigeoclonium, Dinobryon, Synedra, Ceratium.
Waste water sample	Bacteria: Bacillaria, Fragilaria, Spirilla, Campylobacter jejuni, Vibrio cholerae, Amoeba, Bacillus, Coccus
Sea water sample	Chaetoceros, Rhizosolenia, Pleurosigma, Scytonema, Fischerella, Lauderia

Based on the microscopic analysis, the following results were obtained:

Different water bodies show a variety of microorganisms. The presence of certain microorganisms indicates polluted and non-productive water bodies.
In the pond water sample, the high density of phytoplankton is indicative of the high concentration of oxygen and nutrients that support diverse organisms of different trophic levels. Such water bodies are considered productive ones.
The wastewater sample is usually rich in faecal organic matter; the presence of pathogenic bacteria indicates the decomposition of the organic waste, reducing the levels of dissolved oxygen in the water and making it unfit to support other useful life forms.
Thus, the biological assessment of water bodies can identify pollution levels, productivity, and trophic status.

FAQs on Analysis of Aquatic Lifeforms in a Water Sample

Q1. Define water body productivity.

Ans. A water body’s productivity is influenced by the amount of plankton it contains and the amount of solar energy that autotrophic organisms are able to absorb in a given amount of time.

Q2. What is the trophic status of a water body?

Ans. The trophic status of a body of water is a comparative indicator of the lake’s biological productivity. It is a system of grading water bodies according to how much biological productivity they can support.

Q3. List five examples of aquatic microorganisms.

Ans. Volvox, Closterium, Navicula, Nostoc and Microcystis are some of the common examples of aquatic microorganisms.

Q4. Describe the characteristics of a productive water body.

Ans. Productive water bodies have a high density of phytoplankton, indicating a high concentration of oxygen and nutrients that support a varied range of organisms at various trophic levels.

Q5. Describe the characteristics of a non-productive water body.

Ans. A non-productive water body has fewer trophic levels, a very low density of organisms per unit area, and relatively transparent waters with low mineral concentrations and dissolved oxygen, and these characteristics all contribute to its non-productiveness.