Aquatic Entomology ZOOL 484/584 Policies Course outline - website.
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Transcript of Aquatic Entomology ZOOL 484/584 Policies Course outline - website.
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
Where do you find aquatic insects?
• Water
• Lentic =
• Lotic =
• Highest diversity AI in lotic ecosystems
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
Hydrograph
• Record of discharge
0
10000
30000
50000
70000
5/30/04 6/9/04 6/19/04 6/29/04 7/9/04 7/19/04 7/29/04 8/8/04 8/18/04 8/28/04
Cub
ic f
eet
/ sec
1st 2nd
Material carried by flow
• Particles move along bed = bedload
• Suspended load = silt, clays
• All sediments from erosion: – Streambed, bank regions
What causes sediment transports?
• Flow events that influence channel form
• Human impacts: – Ag run-off, urban run-off, channelization, etc.
Discharge relationships• Profile: steep headwaters, flatten with distance
– Particle size decreases
• Sinuosity
Depos
ition
Erosio
n
Discharge relationships• Floodplain:
• Pool-riffle
floodplain
channel
terrace
pool
riffle
pool riffle
Effects of flow on organisms
• Adaptations of aquatic invertebrates– Attachment devices: hooks, sticky stuff,
suckers
– Body shape: flattened, streamlined
Substrate
• Wentworth scale– Boulder: > 256 mm– Cobble: 64-256 mm– Pebble: 16-64 mm– Gravel: 2-16 mm– Sand: 0.063-2 mm– Silt: < 0.063 mm
Most stream organisms live in/on substrate
• Lithophilous = stony substrate
• Psammophilous = sand substrate
• Burrowing
• Xylophilous = wood-dwelling
• Phytophilous = plants
How does streamflow affect:
• Water temperature?
• Channel geomorphology?
• Habitat diversity?
• A “master variable”
River management has been based on:
• Species of interest
• Commercial interests
• Sportfishing interests
• Not working!
Recent advocates suggest understanding/restoring natural
flow regime:
• Magnitude
• Frequency
• Duration
• Timing
• Rate of change
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
Three basic RCC Principles
• 1. Stream communities are based on continuous gradient of physical variables that change from headwaters to mouth
Three basic RCC Principles
• 2. Communities cannot be divorced from riparian zone or geomorphic catchment.
Three basic RCC Principles
• 3. Downstream assemblage is inextricably linked to processes occurring upstream.
Major prediction of RCC
• Longitudinal changes in abundances of functional feeding groups and their food resources.
RCC
• Predictable changes in assemblages with stream distance:
• Headwaters = leaf inputs -- shredders, collectors
Problems with RCC
• Not all streams are the same: spring-fed, arid riparian, blackwater
• Large rivers -- little studied; grazers are present
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
Alternatives
• Serial discontinuity concept (Stanford + Ward 1983)
• The effect of a dam is to “reset” the RCC
Alternatives
The riverine ecosystem synthesis. 2006. Thorp, Thoms, Delong.
Combines previous ideas:Hydrogeomorphic patches Functional process zones
Underground aquatic habitats
• Caves, hyporheic zone
• Organisms live in substrates or in caves
• Caves typically have high endemism