AQUATIC ECOLOGY AND LIMNOLOGY

1. IKENWEIWEBolatitoNafisatSENIOR LECTURERDEPARTMENT OF AQUACULTURE AND FISHERIES MANAGEMENTUNIVERSITY OF AGRICULTURE, ABEOKUTA AQUATIC ECOLOGY AND LIMNOLOGY titobola2007@yahoo.com, 08033770265

2. AQUATIC ECOLOGY AND LIMNOLOGY FIS 703 (3 Units)

3. Course outline • Classification of aquatic systems.  • Physio-Chemical parameters of aquatic environment plankton and benthos.  • Primary and Secondary Production, • energy budget

4. The basic needs of aquatic biota? • Carbondioxide • Oxygen • Sunlight • Nutrients- food & minerals

5. Types of Aquatic Ecosystems • Freshwater Ecosystems • Standing Water- lakes & ponds • Moving Water- rivers & streams • Transitional Communities • Estuaries • Wetlands- bogs/fens, swamps, marshes • Marine Ecosystems • Shorelines • Barrier Islands • Coral Reefs • Open Ocean

6. Freshwater Freshwater contribute about 0.31% and many of the large rivers of the world lie in the tropical and sub-tropical zones

7. Transitional Communities • ESTUARIES • Where freshwater dumps into ocean • Brackish (less salty than seawater) • Has rich sediments that often form deltas • Productive & biodiverse • Organisms adapted to varying levels of salinity as tide ebbs & flows • “Nursery” for larval forms of many aquatic species of commercial fish & shellfish

8. Transitional Communities • WETLANDS • Land saturated at least part of the year • Swamps- have trees like bald cypress; high productivity • Marshes- no trees; tall grasses; high productivity • Bogs/Fens- may or may not have trees; waterlogged soil with lots of peat; low productivity • Fens- fed by groundwater & surface runoff • Bogs- fed by precipitation Swamp Fen Bog

9. Marine Ecosystems • SHORELINES • Rocky coasts- great density & diversity attached to solid rock surface • Sandy beaches- burrowing animals • Threats- due to hotels, restaurants, homes on beach, more plant life destroyed, destabilizing soil, susceptible to wind & water erosion • Insurance high; danger of hurricanes, erosion • Build sea walls to protect people but changes & endangers shoreline habitat

10. MARINE • Oceans, • Seas, and • Other saline water • They all constitutes 97.69% and few usually contains higher nutrient concentrations than the sea water

11. Universal solvent • Water is a universal solvent. • There are also a number of minor constituents in solution, • variety of colloidal materials, both inorganic and organic. • Several gases are also found in natural water. • Water contains larger or smaller concentration of all elements found in the earth crust and in the atmosphere. • Furthermore, most of the organic compounds synthesized by living organisms may be found in water.

12. Dissolved gases The gases that can be found in dissolved form in water include: • oxygen, • carbon dioxide, • nitrogen, • ammonia, • hydrogen sulphate and • methane

13. Mineral constituents Mineral constituents of water include calcium, magnesium, sodium, potassium, iron, manganese, aluminium, zinc, copper, molybdenum, sulphur, chlorine, fluorine, iodine, boron and silicon. These elements are usually present as ions or complex organic or inorganic molecules.

14. Soluble Organic Matter Water soluble organic matter include: • sugar, fatty acids, • humic acids, tannin, • vitamins, amino acids, • peptides, protein, • plant pigments, urea and • many other biochemical compounds

15. Suspended Inorganic Matters The suspended inorganic matters include: • colloidal clay and • coarse suspension of soil particles.

16. Colloidal or suspended particles are: • remains of organism in various stages of decay, • living phytoplankton, zooplankton, fungi and bacteria

17. TYPES OF WATER TYPES OF WATER Lotic i.e flowing water Lentic i.e. static or stagnant water

18. LIMNOLOGY

19. LIMNOLOGY • LIMNO means lake, • LOGY means study

20. LIMNOLOGY It is the study of fresh water habitat which involves the study of physical chemical and biological as well as geographical location (longitude and latitude) characteristics of fresh water environment.

21. Limnology is divided into two: • Lentic water which is static, water lakes and pond • Lotic water which is flowing, streams and rivers

22. PHYSICAL LIMNOLOGY These include: • Temperature, Light, • Turbidity (colour), Viscosity, • Water density, • Water current (speed and direction), • Depth, • Amount of suspended/floating/sinking organisms, and • Physical nature of substance (atoms).

23. TEMPERATURE Temperature is defined as the degree of hotness or coldness.

24. Effects of temperature • Affect states of water (solid, liquid and gas). • Temperature also affect dissolved gas e.g. amount of soluble salt in water increases as temperature increases • Affect biology of aquatic organisms.

25. Difficult to transfer fish geographically except when water is heated artificially in cold region • It also affect solubility e.g. in warm water, fertilizer dissolved faster, herbicides act quicker, rotenone degrades faster and rate of oxygen consumption by decaying manure is greater.

26. Effects of temperature cont’d Metabolism In high temperature rate of metabolism is increase, hence increase growth as the organisms require more than enough food to supply energy with which to compensate the high metabolic rate

27. Effects of temperature cont’d Reproduction • Tropical fish would breed only at temperature greater than 20oC. Embryo develops into fingerling slow at low temperature of less than 20oC. • At high temperature (30oC) some aquatic organism hibernate in mud, under stones • zooplankton lay eggs with cyst preparing for drought.

28. Effects of temperature cont’d Thermal stratification and mixing • Water is divided into 1,2, or 3 parts. Upper part warmer, lower part colder and temperature decreases with depth, • Dividing water into Epilimnion, Hypolimnion and middle Metalimnion with a a sharp change in temperature called Thermocline.

29. At high temperature water become lighter, less dense and mixing (upwelling is increase). • Even at different part of a river e.g. edges are warmer, lighter, cooler and denser towards middle. • Shallow depth at the edge with low volume i.e. horizontal zonation.

30. VARIATIONS IN WATER TEMPERATURE The variation in temperature of water bodies are: • Partial variation in temperature • Diurnal variation • Seasonal variation

31. WATER STRATIFICATION (THERMAL) Due to temperature difference, Lentic water is divide into three layers, • Epilimnion, • Hypolimnion and • Metalimnion

32. UPWELLING Upwelling is caused as a result of thermal stratification

33. Classification of Upwelling Upwelling classified on the basis of number of times to occur includes: • MONOMICTIC - upwelling occur once in a year e.g. in Nigeria, it occur during rain of July - Oct. • DIMITIC - upwelling that occurs twice in a year. During rain and harmatan e.g. North Nigeria

34. POLYMICTIC - upwelling occurring several times in a year. Most ideal for aquaculture. • MEROMICTIC - uncompleted upwelling only some partial, not reach lower part • HOLOMICTIC - complete mixing of both lower and upper part

35. Measurement of temperature • Simple mercury in glass thermometer that ranges between 0oC-50oC e.g. reversing thermometer and thermogram can be used to measure temperature of 1000km away on satellite.

36. Temperature can also be measured using: Electrical thermometer operated using batteries and resistance wire with amount of current to temperature

37. DENSITY • Density is mass per unit volume (g/cm3). • Closely related to viscosity and specific gravity. Viscosity is the relative amount of water molecules in relation to one another. • Water density affect movement of organisms. Organisms can move on dense water than on light water by floating.

38. Density and Temperature Density is also affected by temperature, increase in temperature result in low density though to a maximum temperature of 4oC when it is constant

39. Water Density and Salinity • Water density is also affect by salinity (amount of salt in water). • Water containing high salt concentration has increase water density compared with water with low salt concentration.

40. Measurement of Density Density can be determined by using: • Hydrometer • Specific gravity bottle

41. LIGHT/WATER TRANSPARENCY This is the amount of light entering the water

42. Factors Affecting Water Transparency • Light intensity • Angle of incident ray • Geographical area (higher in the tropics) • Time of the day • Water movement • Season • Water quality

43. TURBIDITY Amount of suspended solids in water

44. Effect of Turbidity When light penetrated water, suspended solid absorb/reflect light rays reducing amount of light going beyond them.

45. Thus, the more dissolved solid, the more turbid water and the less light penetrate it.

46. Effects of Light Intensity • Embryo activity • Breeding period • Visibility • Avoidance of enemies Light intensity affect :

47. Effects of light intensity cont’d At optimum light intensity • Higher photosynthesis thus dissolved oxygen released into the atmosphere and carbon dioxide is removed • More nutrients NO3-, PO4-, etc are utilized thus pH becomes greater (alkali) as all the acidic CO2 are used up.

48. Measurement of water transparency • PHOTOMETER which convert radiant energy of light into electric energy and recorded. • SECCHI DISC measure light depth penetration.

49. WATER COLOUR • True water colour is caused by the amount of substance in solution/ colloidal suspension in it. • colour result from unabsorbed light ray.

50. The main reason the ocean is blue is that water itself is a blue-colored chemical. Optical scattering from water molecules provides a second source of the blue color, but colored light caused by scattering only becomes significant with extremely pure water