Limnology

An introduction to limnology

1. Limnology - An Introduction Dr. V P Saini Dean College of Fisheries, Kishanganj

2. Introduction Civilizations have depended on water bodies such as lakes, reservoirs, rivers and wetlands . Its essential not only to sustain human life but also to support the activities that form the basis for thriving economics . Though the water resources are essential to human societies who could pollute and degrade and limiting their beneficial uses . Agriculture , mining, urban development and other activities can pose risks to freshwater bodies and hence steps have to be taken to reduce these risk factors .

3. Unique Properties of water

4. Unique Properties of water

5. Hydrology Cycle

6. Distribution of Earth’s Water Water covers about 2/3 of the Earth’s surface

7. What is Limnology? - Limnology is the study of inland waters . - It is a branch of science which deals with the study of inland waters . The term Limnology is derived from Greek word; Limne means lake and logos means knowledge. Limnology is often regarded as a division of ecology or environmental science. This includes the study of lakes, ponds, rivers, reservoirs, swamps, streams, wet lands, bogs, marshes etc. Hence, it is commonly defined as that branch of science which deals with biological productivity of inland waters and with all the causal influences which determine it (Welch, 1963).

8. Welch (1935) conceived the problem of “Biological productivity” as the central theme of Limnology. He defined Limnology as that branch of science which deals with all causal influences which determine it . In short, Limnology is the study of all aquatic systems including lakes, wetlands, marshes, bogs, ponds, reservoirs, streams, rivers etc. with regard to their physical chemical and biological characteristics . In addition to the above, certain other terms, like Hydrobiology, Freshwater Biology, Aquatic Biology, Aquatic Ecology etc , are sometimes loosely used as synonymous to the word 'Limnology'. But, most of these terms are names under which a diverse variety of subject matter is included and only a part of it is limnological in nature.

9. History of Limnology F.A . Forel, "Father of Limnology L ac Leman (Lake Geneva) -- began biological studies S.A . Forbes ,( 1887 ) Lake as a Microcosm-Beginnings of ecosystem ecology Birge and Juday sampled many lakes -- comparative approach, 'the data will speak ' versus hypothesis testing Thienemann and Naumann Lake classification; Continuation of ecosystem ecology G.E . Hutchinson Treatise of Limnology (1957 first volume) F.A. Forel G.E. Hutchinson August Thienemann Einar Naumann E.A. Birge Chancey Juday

10. Inland waters The inland waters which include both fresh water masses and estuarine waters of varying salt content are clearly distinguishable from the salt waters of the oceans . The inland water masses are discrete and being isolated within the specific land area, acquire the characteristic chemical composition of the land, by exchange between soil and water. The oceanic water on the other hand is open and mixing together by wind action and currents and therefore more homogeneous in chemical composition. However , the land water exchange is limited to coastal areas. The estuarine waters are mixtures of sea and freshwater, but with the higher content of salts in the sea water (150 – 200 times that of freshwater), are dominated by the sea water effects. According to Hutchinson (1959), limnology is the large variety, individual and groups of inland water bodies, the diversity being caused by the diversity of their origin as well as by the diversity of their chemistry and biology.

11. Inland Water Resources

12. Types of inland water Frey (1960) has classified inland waters in three different ways Whether the water is stationery or flowing Whether the water mass is natural or artificial Whether the water is permanent / temporary . Stationery or flowing Waters Flowing waters (Lotic waters) Standing waters (Lentic waters) Natural or artificial Natural bodies of water : Certain parts of the world are endowed with an abundance of natural waters serving human needs. Artificial bodies of water: According to man’s needs water bodies are created artificially. It includes ponds, wells, tanks reservoirs etc.

13. Types of inland water Based on seasonal duration ponds can be classified into two types. 1 . Temporary ponds 2 . Permanent ponds Temporary – those in which the basin contains water at certain times or seasons and becomes dry at others Temporary ponds divided into three types Vernal ponds: Water exists only in spring season. Vernal Autumnal pond: Water exists in those ponds during spring and autumn and they dry in summer. Aestival ponds: Water persists in these ponds throughout the season but it freezes during winter. Permanent - Those which contain some water the year round .

14. Key Questions What is Environment? What is ecology ? What is ecosystem? What are the major components of an ecosystem?

15. What is Environment? The surroundings or conditions in which a person, animal, or plant lives or operates . All the physical surroundings on Earth  are called the environment. The environment includes everything living and everything nonliving. The nonliving part of the environment has three main parts: the atmosphere, the hydrosphere, and the lithosphere.

16. What is Ecosystem? An Ecosystem is a self regulating group of biotic communities of species interacting with one another with their non-living environment exchanging energy and matter.

17. What is ecology? Ecology—Greek oikos meaning house Ecology is the study of living and non components and their interactions. Study of how organisms interact with one another and their non-living environment (biotic and abiotic components)

18. Characteristics of an Ecosystem Structure of ecosystem Biotic Structure Abiotic Structure Functions of Ecosystem Trophic Structure Food Chains Food Web Ecological Pyramids Energy Flow Nutrient Flow Ecological Succession Types of Ecosystems

19. Major Ecosystem Components Abiotic Components Water, air, temperature, soil, light levels, precipitation, salinity Sets tolerance limits for populations and communities Some are limiting factors that structure the abundance of populations Biotic Components Producers, consumers, decomposers Plants, animals, bacteria/fungi Biotic interactions with biotic components include predation, competition, symbiosis, parasitism, commensalism etc.

20. Limiting Factors on Land & in H 2 O Terrestrial Sunlight Temperature Precipitation Soil nutrients Fire frequency Wind Latitude Altitude Aquatic/Marine Light penetration Water clarity Water currents Dissolved nutrient concentrations Esp. N, P, Fe Dissolved Oxygen concentration Salinity

21. Biotic Components of Ecosystems Producers=autotroph Source of all food Photosynthesis Consumers=heterotroph Aerobic respiration Anaerobic respiration Methane, H 2 S Decomposers Matter recyclers… Release organic compounds into soil and water where they can be used by producers

22. Producers - the first trophic level Autotrophs (“self-feeders”) = organisms that capture solar energy for photosynthesis to produce sugars Green Plants Cyanobacteria Algae Chemosynthetic bacteria use the geothermal energy in hot springs or deep-sea vents to produce their food

23. Consumers: organisms that consume producers Primary consumers ( second trophic level ) Organisms that consume producers Herbivores consume plants/algae: Zooplankton Secondary consumers ( third trophic level ) Organisms that prey on primary consumers: Herbivores fish (Rohu, silver carp, etc.) Tertiary Consumers ( fourth trophic level ) Predators at the highest trophic level Consume secondary consumers Are also carnivores Omnivores = consumers that eat both plants and animals

24. Detritivores and decomposers Organisms that consume nonliving organic matter Enrich soils and/or recycle nutrients found in dead organisms Detritivores = scavenge waste products or dead bodies Decomposers = break down leaf litter and other non-living material Fungi , bacteria Enhance topsoil and recycle nutrients

25. Food webs show relationships and energy flow Food chain the relationship of how energy is transferred up the trophic levels Food web a visual map of feeding relationships and energy flow Includes many different organisms at all the various levels Greatly simplified; leaves out the majority of species

26. Food Webs and the Laws of matter and energy Food chains/webs show how matter and energy move from one organism to another through an ecosystem Each trophic level contains a certain amount of biomass (dry weight of all organic matter) Chemical energy stored in biomass is transferred from one trophic level to the next With each trophic transfer, some usable energy is degraded and lost to the environment as low quality heat Ecological Efficiency : The % of usable energy transferred as biomass from one trophic level to the next (ranges from 5-20% in most ecosystems, use 10% as a rule of thumb) Thus, the more trophic levels or steps in a food chain, the greater the cumulative loss of useable energy…

27. Energy, biomass, and numbers decrease Most energy organisms use is lost as waste heat through respiration Less and less energy is available in each successive trophic level Each level contains only 10% of the energy of the trophic level below it There are far fewer organisms at the highest trophic levels, with less energy available A herbivorous fish’s ecological footprint is smaller than a carnivorous fish’s footprint

28. Pyramids of energy, biomass, and numbers

29. Pyramids of Energy and Matter Pyramid of Energy Flow Pyramid of Biomass Heat Heat Heat Heat Heat 10 100 1,000 10,000 Usable energy Available at Each tropic level (in kilocalories) Producers (phytoplankton) Primary consumers (zooplankton) Secondary consumers (perch) Tertiary consumers (human) Decomposers

30. Ecological Pyramids of Energy

31. Ecological Pyramids of Biomass