1. Aquatic Ecology

2. How much water is there on Earth?

3. Habitats and Communities Marine systems: three major zones 1.Off shore or open sea 2.Neritic or near shore 3.Intertidal – alternately submerged and exposed Few insects some of great interest – discuss later Devoid of insects

4. Habitats and Communities Estuaries: brackish water Ecotone between inland water and the sea Richer aquatic insect fauna than marine

5. Habitats and Communities Lotic: inland running water 1.Crenal – spring fed headwaters 2.Rhithral – streams and small rivers 3.Potamal – large rivers Highest diversity of aquatic insects

6. Habitats and Communities Lentic: inland standing water 1.Lacustrine – lakes and ponds 2.Palustrine – marshes and swamps –Shallow habitats –Ecotones between aquatic and terrestrial Greatest insect diversity associated with vegetation

7. Habitats and Communities Subterranean waters: Hypogean 1.Troglal – caves 2.Stygal – groundwater Relatively sparse insect communities except were merging with surface waters

8. Habitats and Communities Biotic Community: Comprises all populations in a given habitat -- including everything from bacteria to vertebrates and higher plants

9. Habitats and Communities “Planktonic Community” Plankton – organisms that remain suspended Adaptations for vertical migration and/or to remain at certain depths Few insects adapted to planktonic existence

10. Habitats and Communities “Nektonic Community” Nekton – Strong swimmers not at the mercy of the currents. Few insect representatives

11. Habitats and Communities “Pleustonic Community” Pleuston – Organisms at air-water interface Atmospheric breathers that require aqueous medium for other needs

12. Habitats and Communities “Benthic Community” Benthos – organisms associated with substratum Bottom materials, plant beds, logs or other solid surfaces

13. Lentic Freshwaters Lakes provide diverse habitats for aquatic insects Environmental conditions –Distinct spatial gradients –Temporal changes pronounced Aquatic insect communities change w/ gradients in lakes and between lake types

14. Lake Zonation Limnetic Zone – open water devoid of rooted vegetation Littoral Zone – shallow marginal areas characterized by rooted vegetation Sublittoral Zone – transition between well- illuminated upper strata and Profundal Zone Profundal Zone – light insufficient for photosynthesis

15. Lake Zonation

16. Lake Communities Pleuston: organisms associated with surface film Epipleuston – upper surface –Water striders Hypopleuston – lower surface Meropleuston – not continuous resident –Mosquito larvae

17. Lake Communities Pleuston: Adaptations for surface residence –Small size –Furcula Collembola –Hydrophobic cuticle Gyrinids have hydrophobic dorsum and wettable venter

18. Lake Communities Pleuston: Three families of Hemiptera = striders –Hydrometridae – elongate body and legs Water measurer –Gerridae and Veliidae Supported by full length of tarsi Tarsi covered with “hairpiles” Secrete substance that lowers surface tension

19. Lake Communities Pleuston: Diptera limited to mosquitoes Hydrophilid beetles “walk” inverted on underside of water surface

20. Lake Communities Plankton: Insects poorly represented Chaoboridae only planktonic insect

21. Lake Communities Chaoboridae: World wide –Lakes and ponds Nearly transparent Prehensile antennae Feed on zooplankton and mosquitoes

22. Lake Communities Chaoborus: Tracheal system reduced to kidney shaped air sacs –One pair thoracic; another in abdomen Use these “hydrostatic organs” to adjust buoyancy

23. Lake Communities Chaoborus: 2 types of vertical migration –Full – generally in lake species Reside in bottom mud during day Feed in water column at night –Reduced – predominately in pond species = Remain in epilimnion

24. Lake Communities Chaoborus: Limited migration of some species may explain why they are missing from lakes with fish (C. americanus) Others coexist with fishes (full), and are found in fishless lakes (reduced; C. flavicans)

25. Lake Communities Chaoborus: Different larval instars exhibit different migratory behavior C. trivittatus –1 st and 2 nd instars restricted to surface water –3 rd and 4 th move to deeper water during day –Smallest at surface, size  with depth

26. Lake Communities Chaoborus: –Regular depth distribution of size classes apparently related to food size distribution and predation Larger items generally deeper Greater vulnerability to visual predation

27. Lake Communities Chaoborus: Light = entraining agent –Benthic & planktonic phases can be artificially reversed in lab –instars react differently

28. Lake Communities Chaoborus: Oxygen = entraining agent –High 0 2 1% migrated –Low 0 2 30% migrated

29. Lake Communities Chaoborus: Horizontal migration –Spring migration of larvae to littoral zone –Adaptation enabling exposure to warm water prior to pupation

30. http://cfb.unh.edu/CFBkey/html/m ovies.html#

31. Lake Communities Chironomidae: 1 st instar adapted to planktonic existence for dispersal –Larvae positively phototactic 1-3 days –Vertical migrations common w/ diel light –As larvae mature shift from photophilous to photophobic

32. Lake Communities Chironomidae: Late instars may again enter plankton 1.Move to well-aerated water 2.In some species, late instar individuals follow pattern described for 1 st instars

33. Lake Communities Ranatra montezuma: Hemipteran Nocturnal planktonic behavior As light drops below 100 lux, move from littoral to limnetic zone Feed on Hyalella montezuma, return to littoral zone during day

34. Lake Communities Nekton: Nekton distinguished from plankton by directional mobility; from benthos by association with open water Although many aquatic insects swim, they are associated with hard substrate

35. Lake Communities Nekton: Truly nektonic species restricted to a few hemipterans and coleopterans Hemiptera nektonic species include Notonectidae, Corixidae and Belostomatidae

36. Lake Communities Nekton: Anisops and Buenoa (Notonectidae) use hemoglobin to control buoyancy Prey on small arthropods in open water column

37. Lake Communities Nekton: Relationship between habitat and leg structure –Buenoa – open water –Hind legs for rapid pursuit –Forelegs and midlegs for prey capture

38. Lake Communities Nekton: Relationship between habitat and leg structure –Notonecta – underside of surface film Feed on moving prey as well as those caught in surface film Leg structure is intermediate

39. Lake Communities Nekton: Corixidae +Elongate, flattened, hair-fringed hindlegs +Most restricted to water < 1 m Planktivorous spp. are nektonic

40. Lake Communities Nekton: Belostomatidae –Most are sit and wait predators –Lethocerus = nekton Coleoptera –Only largest Dytiscidae and Hydrophilidae

41. Lake Communities Benthos: Majority of insects in lentic habitats are benthic Collectively, aquatic insects make up to 90% of total benthic fauna

42. Lake Communities Benthos: Several orders have highest diversity and abundance in lentic habitats –Odonata (dragonflies) –Hemiptera –Coleoptera –Diptera (some families exclusively lentic) –Hymenoptera –Lepidoptera –Neuroptera

43. Lake Communities Benthos: The composition and relative abundance of aquatic insects is integrated along depth profiles

44. Lake Communities Benthos: Hutchinson - insect fauna of lakes fall into three depth categories 1.Aquatic adults that never developed gills –Hemipterans and coleopterans –Rarely occur in water depth more than 3 m –Most surface for air

45. Lake Communities Benthos: Hutchinson - insect fauna of lakes fall into three depth categories 2.All other orders with exception of Diptera Amphibiotic (aquatic larva, terrestrial adult) Extract O 2 from water Restricted to relatively shallow water

46. Lake Communities Benthos: Hutchinson - insect fauna of lakes fall into three depth categories 3.Only certain dipterans have colonized profundal zone –Amphibiotic –Chaoboridae –Chironomidae

47. Lake Communities Taxonomic richness of benthic insect communities declines with depth Max richness at depths of 1-2 m

48. Exam topics

49. Hoeinghaus et al. 2007 Which river concept explains energy sources in 10 tribs of Parana’ river? Low-gradient, high gradient, reservoirs C,N isotopes for fishes, molluscs, plants, detritus Big conclusions? –Lowland river foodwebs = C from aquatic macrophytes –Reservoirs = C from algae more important –High gradient rivers = C from filamentous algae Relate to river concept?

50. Lytle and Poff 2004 Adaptations to survive floods and droughts ID adaptations Modes: know examples Timing of flow = life history adaptations Predictability = behavioral adaptations Magnitude/freq = morphological adaptations Human impacts

51. Stone et al. 2005 Macroinvertebrates of ag streams What variables impact them? Methods? Sites? Sampling? What attributes were compared? Which attributes varied with physical variables? What impacts caused low scores for macroinvertebrates?

52. Merritt and Cummings Chapter 3 Sampling Devices Sorting, preservation Taxonomic resolution

53. Merritt and Cummings Chapter 5 Habitat, life history Marine paradox Hydraulics Habitats Upstream movements