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Aquatic Ecology

Aquatic Ecology. Objectives. Discuss biodiversity and endangered species. Examine the needs of all aquatic environments. Discuss the three types of aquatic environments. Identify various zones in a lake. Analyze the trophic stages of a pond, lake, or stream.

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Aquatic Ecology

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  1. Aquatic Ecology

  2. Objectives • Discuss biodiversity and endangered species. • Examine the needs of all aquatic environments. • Discuss the three types of aquatic environments. • Identify various zones in a lake. • Analyze the trophic stages of a pond, lake, or stream. • Discuss and define biological indicators. • List sensitive and tolerant groups. • Describe how to collect samples. • Identify macro invertebrates in your sample. • Identify and determine the quality of a local stream.

  3. BIODIVERSITY PROTECTION • Hunting and Fishing Laws • By 1890’s, most states had enacted some hunting and fishing laws. • General idea was pragmatic, not aesthetic or moral preservation. • White-tailed deer • Wild turkeys • Wood ducks

  4. Endangered Species Act • Established in 1973. • Endangered are those considered in imminent danger of extinction. • Threatened are those likely to become endangered, at least locally, in the near future. • Vulnerable are those that are naturally rare or have been locally depleted to a level that puts them at risk.

  5. Endangered Species Act Cont’d • ESA regulates a wide range of activities involving Endangered Species: • Taking (harassing, harming, pursuing, hunting, shooting, killing, capturing, or collecting) either accidentally, or on purpose. • Selling • Importing into or Exporting out of the U.S. • Possessing • Transporting or Shipping

  6. Endangered Species Act Cont’d • Currently, the U.S. has 1,300 species on its endangered and threatened lists, and 250 candidate species waiting for consideration. • Number reflects more about human interests than actual status. • Invertebrates make up 75% of all species, but only 9% worthy of protection. • Listing process is extremely slow.

  7. Recovery Plans • Once a species is listed, USFWS is required to propose a recovery plan detailing the rebuilding of the species to sustainable levels. • Total cost of all current plans = $5 billion. • Opponents have continually tried to require economic costs and benefits be incorporated into planning.

  8. Reauthorizing ESA • ESA officially expired in 1992. • Proposals for new ESA generally fall into two general categories: • Versions that encourage ecosystem and habitat protection rather than individual species. • Safe Harbor policies that allow exceptions to critical habitat designations. • (Economic Considerations)

  9. What are the basic needs of aquatic biota? • CO2 • O2 • Sunlight • Nutrients- food & minerals

  10. What factors influence the availability of those basic needs? • Substances dissolved in water- Nitrates, phosphates, potassium, O2 • Suspended matter- (silt, algae) can affect light penetration • Depth • Temperature • Rate of flow • Bottom characteristics (muddy, sandy, or rocky) • Internal convection currents • Connection to or isolation from other aquatic ecosystems.

  11. 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

  12. Types of Aquatic Systems Rivers & Streams Lakes & Ponds Wetlands Estuaries Groundwater Marine system

  13. Freshwater Ecosystems • Usually 0.005% salt • Some exceptions: • Great Salt Lakes- 5-27% salt • Dead Sea- 30% salt • Moving water- high elevations; cold; high O2; trout; streamlined plants • Standing water- lower elevations; warmer; less O2; bass, amphibians; cattails, rushes

  14. Lentic Zones

  15. Lotic Environments

  16. Lotic Environments

  17. Lakes and Ponds • Critical differences from other freshwater systems • Longer residence time • Typically not shaded with most of the surface area exposed to sunlight • Florida lakes are typically shallow and well mixed • Florida lakes are often highly colored, but can have light reaching much of the bottom Photo by Bill Wade

  18. Watershed / Lake Area Ratio • Watershed area relative to lake area will influence the residence time of water in the lake. • This ratio is also a factor in the nutrient loading to the lake

  19. Lake Habitat Zones

  20. Lake Littoral Zone • Functions • Intercepts Nutrients • Refuge from Predators • Nursery for Fish Eutrophic Southern Lake Oligotrophic Northern Lake

  21. Lake Limnetic/Pelagic Zone • Functions • Plankton • Zooplankton

  22. Lake Limnetic / Pelagic Zone • Submerged Aquatic Vegetation (SAV) • Nutrient uptake • Sediment stabilization • Habitat • Oxygen production

  23. Pond Food Web Algae/Plants Fish Nutrients Grazers Nutrients Algae/Plants Grazers Fish

  24. Fish Algae/Plants Grazers Algae/Plants Grazers Fish Algae/Plants Grazers Fish Algae/Plants Grazers Fish Relationship Between Nutrients and Pond Productivity Nutrients Nutrients Nutrients Algae/Plants Grazers Fish Nutrients Nutrients Habitat/Environmental Impacts

  25. Low nutrients Low primary productivity Low grazers and insects Low fish production Clear water Sandy/low organic matter on bottom

  26. Moderate nutrients Increased primary productivity More grazers and insects More fish production Moderate water clarity More aquatic plants Some organic sediment accumulation TROPHIC STATE

  27. High nutrients High primary productivity Large number of grazers and insects Moderate fish production Low water clarity, or Clear with aquatic plants High organic sediment accumulation TROPHIC STATE

  28. Trophic State Change • Nutrients & Productivity • Sediment & Accumulation • Species Shifts • Species Richness

  29. How is a lake stratified and what lives in each level? • Epilimnion- upper layer of warm water; high light & O2; ex: water striders, phyto- & zooplankton, fish • Thermocline (mesolimnion); middle layer; medium light & O2; ex: phyto- & zooplankton, fish • Hypolimnion- lower layer of cold water; lower light & O2; ex: fish • Benthos- bottom level; no light & little O2; ex: anaerobic bacteria, leeches; insect larvae • Littoral- near the shoreline; cattails, rushes, amphibians, etc.

  30. 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

  31. 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 Marsh Bog Fen

  32. Importance of Wetlands • Highly productive- get lots of sunlight, ↑ plants = ↑ animals • Nesting, breeding ground for migratory birds • Slows flooding by absorbing runoff • Silt settles, making water clearer & nutrient rich • Trap & filter water • Natural chemical rxns neutralize and detoxify pollutants • Gives H2O time to percolate thru soil & replenish underground aquifers. • Threats- artificial eutrophication (see slide 13), draining, sedimentation via construction • “Nature’s Septic Tank”

  33. 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

  34. Marine Ecosystems • BARRIER ISLANDS • Low, narrow offshore islands • Protect inland shores from storms • Beauty attracts developers = developers destroy land • New coastal zoning laws protect future development

  35. MARINE ECOSYSTEMS • CORAL REEFS • Clear, warm shallow seas • Made up of accumulated calcareous (made of calcium) skeletons of coral animals • Formation depends on light penetration. • Have a symbiotic relationship with algae • Very diverse, abundant (rainforests of sea) • Threats- destructive fishing (cyanide & dynamite to stun fish), pet trade; about 3/4ths have been destroyed

  36. What factors can alter aquatic ecosystems? • Natural Succession- normal cycle of pond becoming forest • Artificial Succession- humans add N & P to water via fertilizer & sewage causing succession to happen faster = EUTROPHICATION

  37. What factors can alter aquatic ecosystems? • Humans! • Find food • Recreation • Waste disposal • Cooling of power plants • Transportation • Dams, canals

  38. Cyanophyta Chlorophyta Euglenophyta Heterokontophyta Xanthophyceae Chrysophyceae Bacillariophyceae Phaeophyceae Oomycetes Rhodophyta Pyrrhophyta Rotifera Ectoprocta/Bryozoa Arthropoda Crustacea (superclass) Cladocera (suborder) Copepoda (order) Chelicerata (subphylum) Arachnida (superclass) Acari (order) Algae and MicroinvertebratesCan’t be seen with the naked eye

  39. Phytoplankton • Phytoplankton – microscopic plants and some types of bacteria which obtain their energy via photosynthesis. • Important to the ecosystem because • Part of the primary producing community • Assist in recycling elements such as carbon and sulfur which are required elsewhere in the community.

  40. Phytoplankton • Basis for aquatic food chain b/c major primary producers • Huge impact on global primary production • Estimated at 105 – 106 g C/year • More abundant in well-lighted areas with higher temperatures • Relatively unspecialized physiology, but are evolved to maintain buoyancy • Very little competitive exclusion • May be unicellular or multicellular

  41. Phytoplankton • Asexual reproduction keep numbers high • Cyanobacteria can double several times/day • Diatoms are slower, but can double every 1-2 weeks

  42. Phytoplankton • Phylogenetically diverse • Important groups: • cyanobacteria • dinoflagellates • euglenoids • green algae • diatoms

  43. Diatoms: Order Centrales • Characterized by centric and often circular form • Note also the numerous punctae (pores)

  44. Diatoms Gyrosigma obtusatum Pleurosira laevis Nitzschia levidensis

  45. Dinoflagellates • Phylum Pyrrhophyta “Whirling flagella” • Habitat: Mostly marine, some freshwater • Notes: • Unicellular protists • 2 dissimilar flagella • Many are photosynthetic

  46. Dinoflagellates Notes: • Heterotrophic dinoflag feed on diatoms or other protists • Marine “blooms” • Red tides

  47. Rotifers • Phylum Rotifera “Rotating wheel” • Habitat: Fresh water • Notes: • Heterotrophic • Corona of cilia provide movement and means to move food toward the mouth.

  48. Rotifers Notes: • Sessile, anchors itself with foot • May enter dormancy and form cyst when env. conditions unfavorable • Cysts last up to 50 years

  49. Bryozoa • Phylum Ectoprocta (=Bryozoa) • “Moss animals” • Habitat: Marine and both lotic/lentic freshwaters • Notes: • Sessile; can be epiphytic, epilithic or epidendric • Colonial; a number of clones inhabit one structure • Extend ciliated tentacles to filter food from water • Often host a number of smaller organisms

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