Cover Image
close this bookBiodiversity in the Western Ghats: An Information Kit (IIRR, 1994, 224 p.)
close this folder1. Front matter
View the document1.1 About this information kit
View the document1.2 Workshop participants
View the document1.3 Introduction to biodiversity
View the document1.4 User survey
View the document1.5 Biodiversity: A synthesis
close this folder2. Threats
View the document2.1 Biodiversity of the Western Ghats
View the document2.2 Threats to biodiversity
View the document2.3 Urbanization and biodiversity
View the document2.4 Population and biodiversity in the Western Ghats
View the document2.5 Pollution in Goa's rivers and estuaries
View the document2.6 Atmospheric pollution and biodiversity
View the document2.7 Managing solid waste
View the document2.8 Traffic in wildlife products
View the document2.9 Effect of tobacco growing on biodiversity
View the document2.10 For those vanishing species
close this folder3. Marine
View the document3.1 Biodiversity of the Arabian Sea
View the document3.2 Seaweeds
View the document3.3 O verexploitation of of marine living resources
View the document3.4 Small-sector coastal fisheries along the Kerala coast
View the document3.5 Coral reefs
View the document3.6 Crabs
View the document3.7 Estuarine shellfish
View the document3.8 Fish
View the document3.9 Coastal ecosystems
View the document3.10 Coastal sand dune vegetation
View the document3.11 Fish breeding and habitat
close this folder4. Fresh- and brackishwater
View the document4.1 Estuarine ecosystems
View the document4.2 Mangroves
View the document4.3 Mangrove communities
View the document4.4 Wetlands
View the document4.5 Freshwater wetlands: Carambolim Lake
View the document4.6 Freshwater algae
close this folder5. Agriculture
View the document5.1 Rice diversity and conservation in the Konkan
View the document5.2 Conservation of traditional vegetables in the backyard
View the document5.3 Genetic diversity in mango and cashew
View the document5.4 Floriculture and arboriculture
View the document5.5 Enriched biodiversity by plant introductions
View the document5.6 Impact of introduced plants
View the document5.7 Effects of pesticides on biodiversity
View the document5.8 Khazan (saline) lands
close this folder6. Plants, fungi and bacteria
View the document6.1 Plant associations of the central Western Ghats
View the document6.2 Rare and endangered flowering plants
View the document6.3 Medicinal resources from the forest and sea
View the document6.4 Poisonous plants
View the document6.5 Fungi: Biodiversity, ecology and use
View the document6.6 Conserving fungi
View the document6.7 Edible mushrooms
View the document6.8 Microbial biodiversity of salt pans
close this folder7. Invertebrates
View the document7.1 Butterflies
View the document7.2 Honeybees to conserve biodiversity
View the document7.3 Mulberry silkworms
View the document7.4 Spiders
View the document7.5 Conserving natural enemies of mosquitoes
View the document7.6 Vermicomposting
close this folder8. Reptiles, birds and mammals
View the document8.1 Snakes
View the document8.2 Crocodiles
View the document8.3 Birds
View the document8.4 Mammals
View the document8.5 Animal diversity in prehistoric rock-art
close this folder9. Appreciating and conserving biodiversity
View the document9.1 Biodiversity and the media
View the document9.2 Role of non-government organizations in conservation
View the document9.3 Watershed management
View the document9.4 Energy conservation and alternatives
View the document9.5 Nature trails
View the document9.6 Sacred groves
View the document9.7 Rehabilitation of iron ore mine wasteland in Goa
View the document9.8 Reforestation to restore mining areas
View the document9.9 Mining: Social and environmental impacts
View the document9.10 Resource utilization in Uttar Kannada district
View the document9.11 Biodiversity of Dudhsagar valley
close this folder10. Reference
View the document10.1 National parks and sanctuaries in the Western Ghats
View the document10.2 Glossary
View the document10.3 NGOs in the Western Ghats states

6.8 Microbial biodiversity of salt pans

Salt pans are rectangular soil-based basins, protected by mud bunds. They are used to collect and evaporate water from the sea or estuaries to make brine and eventually crude crystalline salt. Common salt is not pure sodium chloride; it contains varying amounts of sodium, potassium, calcium and magnesium

Ecology and seasonal cycle

Salt pans in Goa are inundated by tidal waters and monsoon runoff. They undergo three seasonal phases: submerged (June to November), shallow (December to February), and drought (March to June).

The light intensity, temperature, pH and oxygen content of the water and sediments change from season to season. Such extreme physicochemi cal changes are detrimental to normal life, but allow microorganis ms capable of adapting to survive.


Salt pans in Goa

Goa has about 200 salt pans along its 105 km coastline.

Salt-loving microbes

Salt-loving microorganis ms are called "halophiles". They include fungi, diatoms, bacteria and cyanobacteria, which occur as free forms or in associations called "mats". Two types, halophilic archaebacteria and cyanobacteria are of special interest due to their significance to the ecosystem and economic potential.

Halophilic archaebacteria

This unique group of bacteria is one of the oldest forms of life on earth. They can adapt to major changes in temperature, oxygen, salinity and acidity, unlike true bacteria, plants and animals.
Some archacbacteria have photosensory pigments that enable them to use the sun's energy to grow and reproduce.

Salt lovers

· Slightly halophilic: tolerate 5-7% NaCI (salt) content.
· Moderately halophilic: tolerate 8-14% salt content.
· Extremely halophilic: tolerate 14-35% salt content.

As evaporation increases the salinity of a salt pan, only extreme halophiles called halophilic archaebacteria grow.

Types of halophilic archaebacteria

Halobacteria:
Rods, disks, cups, squares, rectangles and triangles.

Halococcus:
Spheres.

Haloarcula:
Change in shape as they grow.


Types of halophilic archaebacteria

In 1980, these remarkable organisms were assigned to an exclusive biological kingdom, "Archaebacteria".

Cyanobacteria

Cyanobacteria have pigments which harness light energy and fix carbon. Some also fix nitrogen and increase soil fertility.

These microorganisms occur in a wide range of forms: spheres, hemispheres, cylinders, elliptical, filaments-branched and unbranched.

Halophilic cyanobacteria:

· Fix atmospheric nitrogen and enrich the nitrogen economy of the neighbouring khazan (saline) paddies.

· Fix atmospheric carbon as biomass which is then available as feed to shrimp cultures of khazan land.

· Take in carbon dioxide and give out oxygen.

Economic importance

Both halophilic archaebacteria and Cyanobacteria could be harnessed for agricultural and industrial use, for instance, to produce biogas. With their ability to adapt to toxic levels of chemicals and physical stress, they could also be used to remove heavy metals, crude oil and suspended matter from polluted water.

Potential uses of halophilic micro-organisms


Halophilic archaebacteria

Cyanobacteria

Biomass

Beta-carotenes, detergents, oil recovery

Food (nutrient supplements), livestock feed production, textile dyes, food colours, biofertilizer production.

Pollution control

Heavy metal adsorption, oil degradation

Heavy metal removal, oil degradation, water recycling

Non-conventional energy

Photochemical energy, biogas

Hydrogen fuel cells, biogas production

Electronics

Artificial light-sensitive - pigments


Salt pans under threat

Goa's salt pans are becoming extinct due to use of land for housing, roads, railways and aquaculture. Pollution (such as oil and grease) from barges and other boats, monsoon runoff from mining areas, and industrial effluents in estuarine waters put a heavy stress on even the tolerant halophilic microorganisms. These pollutants may also contaminate the salt produced in the pans.


Salt pans under threat

Conservation

Salt pans are an important ecological niche for microorganisms involved in the cycling and fixing of oxygen, sulphur, carbon and nitrogen.

· Salt pans should be protected from encroachment and pollution.

· Research is needed to isolate these unique microflora and conserve them for biotechnology research and industrial use.

Prepared by Dr. I. Furtado