Streams are ecosystems that provide the basic requirements for life including water, nutrients, energy, and an electron acceptor like oxygen. Organisms living in streams must find ways to obtain these necessities in the flowing water environment. The riffle habitat within streams provides advantages for both autotrophs and heterotrophs due to higher oxygen, light levels, and habitat structure compared to pools. Woody debris and other obstacles are important for creating microhabitats and retaining organic matter that fuels the food web.

1. Concepts in Stream Ecology Streams are ecosystems

2. Communities of organisms and their physical, chemical, and biological environments Ecosystems

3. Basic needs for life: Water: All organisms on earth need water to live Even Organisms in Aerial milieu Nutrients: We are (mainly) made of CHONSP! Energy: While growing and once grown, need energy! Electron acceptor(s) Fundamental requirements of life

4. 70% by weight of living organisms Babies:78% 1 yr : 65% Men 60%, Women 55% Solvent, Transport, support Source of H and O in metabolic breakdown of protein and carbohydrates What does water do for our cells?

5. Why do we need nutrients? Organisms mainly made of CHONSP Carbohydrates: Mostly CHO store energy, Cell structure for plants (cellulose)

6. Why do we need nutrients? Proteins: CHONS engine for cell metabolism Regulate exchanges Catalyse reactions

7. Why do we need nutrients? Lipids: CHOP Store energy Cell walls: phospholipids

8. How does the energy circulate in cells? The magic molecule: ATP Adenosine TriPhosphate

9. How does the energy circulate in cells? ATP “recharged” by energy rich molecules

10. What about Oxygen? Oxygen: main electron acceptor

11. Take home points All organisms need water, nutrients, energy and electron donors to live Stay wet or drink Get nutrients for cell structures Get energy: Sun light Food Have the best electron acceptor: oxygen

13. Who lives in streams? Make a list of all organisms you can think that live in streams

14. Who lives in streams? Bacteria, virus Amoeba, rotifers Plants: Algae: microscopic and macroscopic Bryophytes (mosses) Angiosperms (flowering plants) Fungi

15. Who lives in streams? Animals: Protozoa: Sponges (Bryozoa) Macroinvertebrates Acoelomate worms Planaria or flatworm (Turbellaria) Nematode or Threadworm, Horsehair worm (Nematoda) Mollusca Clams (Bivalva) Snails (Gasteropoda) Annelida Leeches (Hirudinea or Achaeta) Tubifex worm (Oligochaeta) Bristle worms (Polychaeta)

16. Who lives in streams? Animals: Macroinvertebrates (Cont’d) Arthropods: Spiders (Arachnida) Crayfish, Water flea (Crustacea) Stonefly, Mayflies, Caddisfly (Insects) Vertebrates: Vertebrates Lamprey (Agnatha) Fish (Osteichthyes) Frogs (Amphibians) Water snakes and turtles (Reptiles) Kingfisher, Dipper (Birds) Otter, beaver (Mammals)

17. Algae: What do they look like? Microscopic and macroscopic algae Diatoms commonly comprise the dominate algal group in river biofilms in terms of species number and biomass.

18. Aquatic mosses (Bryophytes) Christmas Moss (Vesicularia montagnei) Zipper Moss – (Fissidens zippelianus)

19. Aquatic flowering plants Myriophyllum spp – Watermilfoils Water lilies – Nuphar spp Glyceria Fluitans

20. Aquatic sponges Freshwater sponges are aquatic animals that grow in lakes, rivers, bogs, and streams attached to submerged rocks, sticks, logs, or aquatic vegetation. These sedentary animals feed by filtering small particles from the water, and so are thought to be sensitive indicators of pollution. The sponges may be colored green by algae that live inside their cells or they may be beige to brown or pinkish in color. Sponges can be delicate to very firm feeling but are not slimy or filmy. Some sponges prefer the underside of logs and sticks; these are usually not green in color.

21. Acoelomate worms Turbellarians or planarians (Turbellaria) possess a pharynx tube that extends to feed on whole small animals or suck tissues from dead or wounded prey. http://trc.ucdavis.edu/biosci10v/bis10v/media/ch16/blood_fluke.html

22. Nematods Nematodes exhibit a wide range of feeding habits: carnivorous, herbivorous and parasitic

23. Horsehair worms Horsehair eggs are laid in the water in long strings where the adults live. After hatching, the larvae penetrate some aquatic insect; they escape in some unknown way from this host and find their way into a second host; usually a beetle, cricket, or grasshopper; in the body cavity of the second host the larvae continue their development eventually passing out into the water where they become mature. Since the adults live only in water, those that survive probably emerge from terrestrial (flying) insects, which constitute their second hosts, that chance to drown in watering troughs and small ponds.

24. Clams Freshwater mussels feed by filtering algae and small particles from the water. Most species have a larval stage that is parasitic on fish. Larvae are released by the female mussel and must locate a certain fish species or die. They usually attach to the host fish's gills or fins where they remain for a few weeks or months. Larval mussels rarely harm infected fish under natural conditions. If essential fish species are removed from the habitat, mussels will not be able to reproduce. Support muskrats, otters, wading birds and game fish

25. Aquatic snails Aquatic snails are a crucial host to the flatworm parasite Herbivores

26. Leeches Leeches suck the blood of fishes, amphibians, birds, and mammals. They also eat snails, insect larvae, and worms

27. Tubifex worms Tubifex tubifex, also called the sludge worm, is a species of tubificid segmented worm that inhabits the sediments of lakes and rivers on several continents. These worms ingest sediments and gain nutrition by selectively digesting bacteria and absorbing molecules through the body wall. The worms can survive without oxygen for months, and can survive in areas so heavily polluted with organic matter that almost no other species can endure. By forming a protective cyst and lowering its metabolic rate, T. tubifex can survive drought and food shortage. Encystment may also function in dispersal of the worm. Ecologically, it is important as a source of food for leeches, crustaceans, insects, and fishes.

28. Bristle worm Mostly in seawater

29. Aquatic Spiders Water spiders breathe air. They use their silk to make a spherical container under the water, attaching the silk to water plants. When this is done they collect air from the surface and place it in the silk container. They even lay their eggs in this trapped air bubble

30. Crustaceans Sawbug Crayfish Daphnia Copepods Mostly herbivores

31. Insects in NC Ephemeroptera – mayflies Plecoptera – stoneflies Trichoptera – caddisflies Odonata – damsel and dragonflies Coleoptera – beetles Megaloptera – Dobson and Alderflies Diptera – True flies EPT

32. Characteristics of a stream Carries water, particulate and dissolved matter at the lowest point of the land upstream

33. Particular longitudinal and transversal shape

34. Highly variable parameters of the ecosystem Viscous milieu Velocity and weight of water create momentum and shear stress at the sediment water interface High variability Velocity, momentum and shear stress Transport of bedload Turbidity and particulate matter Nutrient and oxygen concentrations

35. Stream Ecosystems Mostly downstream fluxes of energy and matter Lateral and vertical the riparian and hyporheic zones

36. Why do you think the riffle could be a good milieu? The riffle: a wonderful milieu

37. The riffle: a wonderful milieu Elevation drop Higher velocity Higher shear stress More resuspension of fine sediments Only bigger particles stay Riffle contain gravel size stones at their surfaces

38. The riffle: a wonderful milieu (Cont’d) Highly porous medium High hydraulic conductivity Water can get into Advective transport of O 2 , nutrients and particulate matter Hydraulic refugia

39. The riffle: a wonderful milieu (Cont’d) Relatively Shallow Smaller cross section area Obstacles relatively bigger Woody debris go agroud Leaf pack can develop

40. How do all organisms find their requirements for life in streams? Water? Source of nutrients? Source of energy? Source of electron donor (oxygen)?

42. Where do organisms find oxygen? Primary producers produce oxygen during daylight: photosynthesis At night and for all other organisms: from water Dissolved oxygen in water

43. Sources and sinks of oxygen in water Sources: Photosynthesis from autotrophs Reaeration at the interface between water and atmosphere

44. Reaeration Partial pressure equilibrium between atmosphere and water dissolved gas mole fraction of any gas, x i , at equilibrium conditions P O2 =0.2095 The colder the water the higher the potential for oxygenated waters

45. Reaeration (Cont’d) DO values also depend on The depth of the water The velocity of the water Water T °C

46. Where is water fast and shallow in streams?

47. Oxygen concentration highest in riffles!!!

48. Can oxygen be a problem? Oxygen content in streams and sediment driven by the ratio between supply and demand. All organisms from bacteria to fish respire and consume oxygen In sediment oxygen can be all consumed: anoxia Oxygen: major driver of stream habitat and biogeochemical processes

49. Challenges when an autotroph in a stream Find a spot Find a point of anchorage Stay in place Find light Find nutrients Avoid being grazed

50. Biofilms

51. Biofilms

52. Increased water exchange in Biofilms

53. Challenges for macrophytes in streams Withstand the currents Obtain nutrients from both sediment and water column

54. Challenges when a fungus or Shredder Have something to shred upon Leaf packs, dead algae macrophytes

55. Riparian plant community = stream organic dynamics

56. Wood Mass Estimates (Valette, et. Al.) Old Growth Streams = 8.33 kg/m ² Second Growth Streams = 0.05 kg/m²

57. Challenges when a fungus or Shredder Have something to shred upon Leaf packs, dead algae macrophytes Capture particulate matter Clogging Not getting washed away Ability to hide

58. Video for capture

60. Challenges when a fungus or Shredder Have something to shred upon Leaf packs, dead algae macrophytes Capture particulate matter Clogging Not getting washed away Ability to hide from current and predators

62. Challenges for scrapers Be were the biofilms are Have oxygen Withstand current Hide or develop strategies against predators

64. Challenges for filters and collectors Have enough oxygen Enough food Not too many fine particles Clogging Hide from predators

65. Challenges for invertebrate predators The food chain above must exist Have enough oxygen Live where the preys live Not get washed away Ephemeroptera

66. Challenges for higher predators Have enough oxygen Find where the insects and fish are Locations to rest, feed and reproduce Depend on the entire food chain above

67. Take home points: Where does energy come from? Light for the autotrophs (autochtonous origin) For most organisms: Dead organic matter Crucial importance of Fine Particulate Organic Matter (FPOM)

68. Why would anyone want to live in a riffle?

69. Why would anyone want to live in a riffle? Autotrophs More light More renewal of nutrients Heterotrophs More oxygen in water and sediment Smaller cross section area thus higher probability of capturing food for the same volume scanned Higher chance for obstacle for leaf packs Woody debris essential as physical barriers

70. Take home points: Why would anyone want to live in a pool? Autotrophs Less shear stress Soft sediment for roots and for nutrient supply Heterotrophs Less shear stress (herbivores) Soft sediment for habitat (Bivalva) Fine particulates for detritivores

71. Take home points: Small obstacles: key to ecosystem health

72. Biological indicators of good health Mayfly (Ephemeroptera) Stonefly (Plecoptera) Caddisfly (Trichoptera) EPT

73. In-Stream habitat Macrohabitats: riffles and pools Microhabitats: bankroots, leaf packs, large woody debris, hyporheos, other vegetation

74. Great diversity of habitat in streams

76. Can search for nutrient, energy, oxygen be altered? Eutrophication Turbidity of water, erosion and increased bedload No woody debris No habitat for the whole food chain

77. Some biological indicators of water quality