AQUATIC STUDIES

1. AQUATIC STUDIES LIMNOLOGY – LAKE ECOLOGY

3. LAKES ARE BROKEN UP INTO SEVERAL ZONES • PHOTIC ZONE- SURFACE TO DEPTH OF NO LIGHT PENETRATION- (VARIES 5-90FT) • EXCESSIVE OXYGEN PRESENT • NUTRIENT PRODUCING ZONE (PHYOTOPLANKTON PRODUCTION BY PHOTOSYNTHESIS)

4. APHOTIC ZONE – NO LIGHT • ONLY FOUND IN OCEANS AND VERY DEEP LAKES • BENTHIC ZONE- FLOOR OF A BODY OF WATER • IN SHALLOW PONDS, STREAMS, AND COASTAL AREAS IT CONTAINS A VARIETY OF ORGANISMS

5. BENTHIC CON’T • IN SHALLOW WATERS, SUNLIGHT REACHES THIS ZONE WHICH CAN SUPPORT PLANT LIFE • LARGE POPULATIONS OF BACTERIA AND FUNGI WHICH DECOMPOSE DEAD ORGANIC MATERIAL

6. PHOTIC ZONE IS DIVIDED INTO TWO SUBZONES • LITTORAL ZONE SHALLOW REGION OF THE LAKE, CHARACTERIZED BY ROOTED VEGETATION, -EMERGANT- CATTAILS, BULLRUSHES -FLOATING- DUCKWEED, LILLY PADS SUBMERGENT-ELODEA, CABOMBA

7. LITTORAL ZONE CON’T • ALSO PRESENT ARE PLANKTON (FLOATING MICROORGANISMS) • PHYTOPLANKTON- ALGAE AND OTHER MICROSCOPIC PLANTS • ZOOPLANKTON- PROTOZOA WHICH FEED PRIMARILY ON PHYTOPLANKTON • THIS ZONE PROVIDES FOOD AND BREEDING SITES FOR: beetles, dragon flies, crayfish, frogs, newts, fish, snails, salamanders, turtles, birds

8. Littoral zone con’t • Per volume of water, the littoral zone produces the most biomass, • A lake may be entirely littoral zone • LIMNETIC ZONE • Deep region of water beyond the littoral zone • No rooted plants • Phytoplankton provide oxygen, and act as producers

9. THERMAL STRATIFICATION

10. THERMAL STRATIFICATION • EPILIMNION- upper stratum, • Temperature change is less than 1 degrees C/ meter of depth • Oxygen concentration is high – phytoplankton, wave action • Water freely circulates • THERMOCLINE- middle stratum, temperature change is greater than 1 degrees C/ meter of depth, few currents

11. Thermal stratification con’t • HYPOLIMNION- bottom stratum, cold water, less than 1 degrees C/ meter temperature change • Little or no current

12. Dissolved Oxygen – results • 28 drops x.5mg/l dissolved oxygen= 14mg/l • Water temperature= 20C • Atmospheric pressure= 750mm/hg • Correction factor= 1 x 14mg/l = 14mg/l • 150% saturation • What does this mean= this water sample has plenty of oxygen in it and would be great for all species.

13. Michigan lakes show seasonal temperature change

14. Fall overturn- as surface water cools, it becomes more dense and sinks • At 4C, water is in its densest state, this water forms the bottom layer • Upon freezing, water expands and becomes less dense • Ice helps insulate the water below it to keep it from freezing

15. Winter kill- deep snow on the ice blocks light to the phytoplankton • Oxygen production is greatly reduced, fish die • Spring Overturn- spring winds circulate water and mix oxygen and nutrients evenly throughout • As the season progresses and the water warms, stratification begins to occur • By summer eplimnion has become larger (about 20’) with high oxygen levels • By late summer decomposers put stress on oxygen levels near the bottom • Warm water holds less oxygen (causes summer kill) • B.O.D.- Biological oxygen demand puts stress on D.O. (dissolved oxygen)

16. Summer kill- caused by oxygen depletion • Occurs in hypolimnion in late summer • Microcystis- scum forming, algae block sunlight • Fish growth is retarded • Sudden death of algae and decay causes B.O.D. to rise drastically

17. Fish populations • The biotic potential of fish • Fish have an extremely high reproductive capacity • 3lb bass- 40,000 eggs • 10lb pike 100,000 eggs • Bluegill- 67,000 eggs • 35 lb Muskie 225,000 eggs

18. Environmental resistance faced by fish • Approximatley 70% of a fish population dies each year • 1,000,000 young hatch • 700,000 die • 300,000 1 yr. old • 210,000 die • 90,000 2 yr. old and so on until there are only 6 fish left after 10 yrs.

19. Actual study- in Ottertail, Minnesota • 15,000 fish netted- only 4% were over a year old • Negative environmental conditions that fish encounter • A. Siltation- (result of bad land practices like logging, farming, public use) • Sediment fills ponds and lakes • Clogs gills • Covers gravel spawning beds • Suffocates eggs of spawning fish • Kills larval food sources • Reduces photosynthesis

20. B. Thermal pollution • Cold water fisheries (trout, salmon) demand water< 70 degrees F. • Power plants heat water -Destroy phytoplankton -Warm water holds less oxygen

21. C. Domestic and industrial pollution D. Eutrophication • Phytoplankton population explodes • Die off in the fall must be broken down by bacteria • Bacteria population explodes • Biological Oxygen Demand (B.O.D.) increases • Fish die from lack of oxygen • Nitrates and phosphates contribute to eutrophication * fertilizer, sewage, detergents

22. E. Exotics -Introduced from foreign waters -Transported by people, boats, and fishing gear -Compete with native species for food and habitat -Lack natural enemies

23. A few examples of what happens when invasive species move in: • The entire Lake Trout population was on the verge of crashing after the sea lamprey invasion until biologists developed ways to keep the lamprey under control. • The hungry, aggressive Round Goby feeds on the eggs and fry of game fish, stressing the native populations. • Invasive purple loosestrife and phragmites spread quickly — firmly taking hold in wetlands, rendering some land unusable along waterfronts and squashing biodiversity. Phragmites are especially good at knocking out other plants in their growth area, secreting a form of acid that proves lethal to those nearby.

24. Eurasian Watermilfoil and Frogbit choke out waterways, which makes the areas unusable to boaters and swimmers. Some invasive plants rob the water of oxygen, causing fish kills. • Industrial plants – including water plants that provide drinking water for cities – have reported significant reductions in pumping capabilities and occasional shutdowns due to zebra mussels. The mussels attach to hard surfaces and colonize on structures, such as boats, water intake pipes, turtle shells, etc. • Industry, government and citizen groups spend tens of millions of dollars on invasive species control every year.

25. Overview Zebra mussels (Dreissena polymorpha) are small, fingernail-sized mussels native to the Caspian Sea region of Asia. They are believed to have been transported to the Great Lakes via ballast water from a transoceanic vessel. The ballast water, taken on in a freshwater European port was subsequently discharged into Lake St. Clair, near Detroit, where the mussel was discovered in 1988. Since that time, they have spread rapidly to all of the Great Lakes and waterways in many states, as well as Ontario and Quebec. Diving ducks and freshwater drum eat zebra mussels, but will not significantly control them. Likely means of spread: Microscopic larvae may be carried in livewells or bilgewater. Adults can attach to boats or boating equipment that is in the water.

26. Zebra mussels

27. BALLAST

28. F. Predation • By fish, amphibians, reptiles birds and mammals

29. Fish activity • Directions: after receiving a fish out of the envelope apply these questions to it. (handout is a classroom copy) • Draw the fish and label – you can use the fish anatomy handout from yesterday. • Looking at adaptations; how are the following adaptated for your fishand what is the advantage A. Mouth B. Body shape C. Coloration D. Horizontal stripes E. Reproduction F. Fin shape/location E. What is the name of the fish

31. Ballast law – exotic species

32. Closure questions 10.2.09 • EXPLAIN THE DIFFERENCES BETWEEN THE PHOTIC AND APHOTIC ZONE- HOW DO THESE DIFFERENCES AFFECT THE LIVING ORGANISMS. • Where can the following zones be found: Epilimnion, thermocline, hypolimnion 3. What percentage of fish species offspring die each year? 4. Why do fish lay so many eggs? 5. EXPLAIN SPECIFICALLY DEALING WITH LAKES AND SEASONS HOW ABIOTIC FACTORS CAN HAVE AN IMPACT ON BIOTIC FACTORS.