LEC 28 - BENTHIC INVERTS

Question 1

theres microbenthos, meiobenthos, and macrobenthos. discuss

Answer 1

-benthos will refer to benthic (on floor/in sediment) organisms

microbenthos: protozoans, juvenile meio-/macroinverts

meiobenthos: benthic forms of pelagic taxa (rotifers, copepods), small oligochaetes, and nematodes

macrobenethos: da big boys
- usually comprise aq juveniles of terre animals (ex mosquito larvae, mayfly larvae)

Question 2

what is the EPT index?

Answer 2

consists of ephermoptera, plecoptera, tricoptera

these species are used to indicate health of a water body (sensitive to poor water quality)

Question 3

what is the difference between CPOM and FPOM? why is this difference important?

Answer 3

COPM = coarse particulate organic matter, FPOM = fine particulate organic matter

CPOM is shredded macrophyte leaf litter etc, FPOM is clumped DOM
– implications on who can eat what

Question 4

the littoral zone breaks down into the upper, middle, and lower littoral with there being a secret fourth zone. explain what all these are, what prim prods are in the zone, and the expected biomass/diversity.

Answer 4

upper littoral: the top of the littoral that gets most light + most waves
- high sediment disturbance
- periphyton are disturbance resistant (ex. stalked filamentous macrohpytes)
- high diversity + biomass, all adapted to resist disturbances

mid littoral: the middle
- submerged macrophytes, periphyton found on epilithon, epiphyton, and epipelon
- still got a good biomass and diversity

sub littoral: the bottom
- periphyton on sediment and rocks only (no macrophytes left)
- LOWER diversity and biomass

the secret fourth thing is the profundal zone below compensation depth, where its not prim prods left
- benthic inverts are chillin tho

Question 5

what is a shredder? tell me about them: what do they eat? where are they found?

Answer 5

shredders are benthic invertebrates who are adapted to chew n shit
- feed on CPOM (macrophytes in lakes, allochthonous inputs in lower order streams) and on stalked filamentous periphyton

PRECONDITIONING!! BREAK IT DOWN NOW!!

Question 6

what are collectors? tell me about them: what do they eat? where are they found?

Answer 6

feed on FPOM
split into two subgroups: the filterers (feed on FPOM in suspension) and the gatherers (feed on FPOM in sediment)

filterers are more common in streams (particles stay in suspension due to turbulence), gatherers are more common in lakes (particles fall out of suspension)

Question 7

what are grazers/scrapers? what is their role in the grander food web

Answer 7

feed on epilithon and epiphyton algae

grazers are important top down controls on prim producers

Question 8

we’re back to da fuckin upper/mid/sub littoral zones! where are the following found:
- shredders
- filterers
- gatherers
- grazers

Answer 8

shredders: anywhere macrophytes are found - upper and middle

filterers: the water column - upper, middle

gatherers: sediment - middle, sub and profundal

grazer: feed on epilithon, epipelon - upper, middle, and lower

Question 9

with respect to the river continuum concept, where are the following likely to be found:
- shredders
- filterers
- gatherers
- grazers

Answer 9

shredders: headwaters, where CPOM is highest

grazers: middle, where turbidity doesn’t fuck w light pen and light reaches the bottom (epilithon/pelon algae are present)

filterers: downstream, where w ppton and FPOM are higher, where waters are slower and ppton can incr in abundance

gatherers: downstream, where waters are slow and sediments fall out of suspension (higher in FPOM)

of filterers and gatherers, filterers dominate