Lecture 5- macroinvertebrates and the river continuum concept Flashcards
How is macro invertebrate sensitivity scored?
-on a scale of 0-12.5
how are macroinvertebrate fucntional groups scored?
on feeding habits
what are the macro invertebrate functional groups? (four)
- shredders
- collectors
- scrapers
- predators
what is periphyton, what does it contain and how does it form? how does it protect?
- periphyton is a microbial biofilm, containing the microbial loop. it is essentially a jelly like matrix that attaches to a surface. this jelly is produced by bacteria and algae
- periphyton is 99% water, which provides organisms in it protection from dehydration when changes in water level occur
what are the three forms of macroinvertebrate food?
- fine particulate organic matter (microbes+zooplankton)
- coarse particulate organic matter
- periphyton
Describe shredders(what they eat etc)
- shredders feed of CPOM, such as decayed leaves and aquatic plants
- snails and crustaceans are the main shredder groups
why do shredders have to wait for leaf decay? what do they wait for?
- leaves are essentially “too hard” for macronivertebrates to consume
- so they must wait for a biofilm of microbes to cover them, and once this biofilm begins breaking the leaf down the macroinvertebrates can eat them
what are the two groups of collectors?
-filterfeeders and gatherers
what do filter feeders utilise?
- fine particulate organic matter
- acquire it from suspension via filter feeding
how do gatherers acquire fpom?
- gather its from SUBSTRATUM (sediment associated larva)
- also called deposit feeders
- feed of sloughed periphyton and feces
what do scrapers feed off? how do they acquire it?
- feed off periphyton via scraping food off the surface
- scrape surface with mouthpart. Eg. Rasping Radula of snails
what do predators feed on? what are the two types of prey?
- feed on other macroinvertebrates via ambushing or overhunting
- feed on suspended (eg. caddisfly) or attached prey
what do predators feed on when small vs large?
-commonly feed on perihpyton when small and macroinvertebrates when large
what does the river continuum concept describe?
-describes the way macro invertebrate distribution changes along a river as it increases in size
what do rivers start in?
-headwater streams
what dominates 1-3 order streams?
- the initial inputs of energy are CPOM from vegetation that lines the catchment
- the dominant benthic invertebrates in headwater streams are COLLECTORS (collecting fpom) and SHREDDERS (breaking down cpom)
- most fish require cool,well oxygenated water
what dominates 4-6 order streams?
- less cpom due to it being broken down by upstream shredders
- greater area for PERIPHYTON PRODUCTION which increase the quantity of scrapers
- collectors also present, filter feeding on broken down fpom coming from upstream
- larger river means warmer waters with less oxygen. Fish must tolerate this
what dominates 6th order and onwards streams?
- large planktonic food web due to large river size
- collectors+filterfeeders dominate
- warmer conditions and even less oxygen for fish to cope with
- large zooplnakton population may also be sustained, feeding off upstream fpom
how is the river continuum concept applied to the real world?
the RCC represents an ideal river with zero pollution. Organic polution in the real world will change macroinvertebrate distribution, so comparing the real to this ideal can allow for understanding of the extend of pollution effects.
what is the difference between allochthonous and autochthonous inputs?
- autochontous inputs are those produced via primary production in the river
- allochontous are organic, external inputs (eg. leaves that fall in)
what are the two variations in DOC in rivers?
- LABILE. meaning substances are easily decomposed and taken up by micro organisms
- REFRACTORY, meaning substances are left over and transported downstream
what happens to doc and cpm as you move downstream?
-decrease in doc diversity, increase in cpom importance
what is the functional group distribution as you progress up stream orders?
Low order streams: more shredders and collectors due to cpom dominance
Intermediate order streams: scraper and collector dominated
High order streams: collector and filter feeder dominated
describe the water framework directive
-was created in 2000 by the EU, focusing on the integrated assessment and management of all
EU rivers
-applies to: rivers, lakes, estuaries, coastal water, groundwater
what did the water framework directive aim to achieve? how did it go about this?
-maintain and restore ecosystem health, by reaching “good ecological and chemical status” of all water bodies by 2015
the directive had a “no deterioration policy for involved fining countries that polluted clear rivers”
what were the advantages of using macroinvertebrate diversity to assess waterquality in the water framework directive?
- cheap and easy
- taxonomy well sorted and common species response known
what were the disadvantages of the water framework directive?
- only measures macroinvertebrate response to organic pollution
- seasonal variability complicates comparability
- some groups (eg. segmented worms) are taxonomically difficult to identify
what are the three filters on the ability of species to settle in a habitat?
- climate regime
- geochemistry of catchment (often a result of underlying bedrock)
- shoreline vegetation (impacts the amount of entering cpom)
