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Aquatic Entomology ZOOL 484/584 Policies Course outline - website.

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Presentation on theme: "Aquatic Entomology ZOOL 484/584 Policies Course outline - website."— Presentation transcript:

1 Aquatic Entomology ZOOL 484/584 Policies Course outline - website

2 What is Aquatic Entomology? Study of Aquatic Insects, –habitat consists mainly of a body of water have key morphological adaptations to assist them in this habitat. course is based on ecology and taxonomy of aquatic insects

3 Where do you find aquatic insects? Water Lentic = Lotic = Highest diversity AI in lotic ecosystems

4 Stream ecology Physical Properties Hydrologic cycle

5 Water in rivers Discharge –Speed of water in channel –Current velocity U –Varies across stream: –Highest where friction is lowest (surface, center of channel) –Approaches 0 at substrate surface

6 Cross-sectional area of stream Width x Depth Total volume at point (discharge, Q) = –W x D x U

7 Hydrograph Record of discharge

8 Material carried by flow Particles move along bed = bedload Suspended load = silt, clays All sediments from erosion: –Streambed, bank regions

9 What causes sediment transports? Flow events that influence channel form Human impacts: –Ag run-off, urban run-off, channelization, etc.

10 Discharge relationships Profile: steep headwaters, flatten with distance –Particle size decreases Sinuosity Deposition Erosion

11 Discharge relationships Floodplain: Pool-riffle floodplain channel terrace pool riffle pool riffle

12 Stream order: always flowing

13 Rivers change over time

14 Effects of flow on organisms Adaptations of aquatic invertebrates –Attachment devices: hooks, sticky stuff, suckers –Body shape: flattened, streamlined

15 Substrate Wentworth scale –Boulder: > 256 mm –Cobble: mm –Pebble:16-64 mm –Gravel: 2-16 mm –Sand: mm –Silt:< mm

16 Most stream organisms live in/on substrate Lithophilous = stony substrate Psammophilous = sand substrate Burrowing Xylophilous = wood-dwelling Phytophilous = plants

17 Substrate size and organism diversity Particle size mm Species richness

18 Water quality and organisms Temperature Oxygen pH Salinity

19 Read Poff et al. (1997) Know: What is “natural flow regime” How to characterize?

20 How does streamflow affect: Water temperature? Channel geomorphology? Habitat diversity? A “master variable”

21 River management has been based on: Species of interest Commercial interests Sportfishing interests Not working!

22 Recent advocates suggest understanding/restoring natural flow regime: Magnitude Frequency Duration Timing Rate of change

23 Lytle & Poff TREE 19:94

24 Natural flow regime Why do streams differ in flow regimes? How have we altered flow regimes?

25 Ecosystem changes along streams River continuum concept (RCC) Vannote et al. (1980) Can. J. Fish. Aquat. Sci. 37:130 Based on forested headwater streams in eastern North America

26 Three basic RCC Principles 1. Stream communities are based on continuous gradient of physical variables that change from headwaters to mouth

27 Three basic RCC Principles 2. Communities cannot be divorced from riparian zone or geomorphic catchment.

28 Three basic RCC Principles 3. Downstream assemblage is inextricably linked to processes occurring upstream.

29 Major prediction of RCC Longitudinal changes in abundances of functional feeding groups and their food resources.

30 RCC Predictable changes in assemblages with stream distance: Headwaters = leaf inputs -- shredders, collectors

31 RCC Midreaches: sunlight = algae -- fewer shredders, more collectors + grazers

32 RCC Downstream: deeper = less light to bottom, less allochthonous inputs -- collectors- filterers

33 Problems with RCC Not all streams are the same: spring-fed, arid riparian, blackwater Large rivers -- little studied; grazers are present

34 Alternatives Flood pulse concept for large rivers (Junk et al. 1989) Allochthonous material has large impact: periodic flooding allows riparian materials to wash into river

35 Alternatives Serial discontinuity concept (Stanford + Ward 1983) The effect of a dam is to “reset” the RCC

36 Alternatives The riverine ecosystem synthesis Thorp, Thoms, Delong. Combines previous ideas: Hydrogeomorphic patches Functional process zones

37 Riverine Ecosystem Synthesis

38 Underground aquatic habitats Caves, hyporheic zone Organisms live in substrates or in caves Caves typically have high endemism

39 Lentic ecosystems Abiotic zones based on light penetration, distance from shore –Littoral, epilimnion, hypolimnion, benthic Stratification


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