LEC 27 - THE PELAGIC ZONE Flashcards
what is the phytobenthos?
benthic algae + periphyton
periphyton being epilithon (on rocks), epiphyton (on submerged macrophytes), and epipelon (on/in sediment)
compensation depth is at about 1% light pen, and below is the profundal zone. what is it, and what is notable here?
the profundal zone is basically just the area where organic material in sediment are decomposed by bacteria
while the littoral zone is determined by light, max biomass is not necessarily at the surface. why?
biomass is a function of light pen and mixing depth
what is the polysaccharide matrix?
an area sitting off submerged macrophytes that acts as an environ for bacteria, algae, detritus, enzymes to chill
r strategists vs k strategists for plants. discuss.
r strategists:
- grow fast
- shorter
k strategists:
- grow slow
- taller, stalked, filamentous/colonial
fundamentally periphyton can be thought of as miniature forests, where taller trees soak up more light (k take longer to grow, but they get higher; r fight for whatever’s left)
periphyton tend to do better in what scenarios
- resource avail
- grazing pressure
- substrate conditions
- sediment suspension
- more resources avail
- lower grazing pressure
- stable substrate (substrate gets shakier as slope gets steeper)
- low sediment suspension
within the polysaccharide matrix there are very few nutrients to spare. what implications would this have for community breakdown? if we compared canopy to understory cells, what would we find?
more mixotrophs further into the matrix, more autotrophs towards the outside of the matrix
in general, canopy has access to more carbon than understory
–> canopy has more autotrophs and understory has more mixotrophs
in terms of consumption in the food web, periphyton and macrophytes have diff roles. what is this difference?
periphyton are way smaller and can be eaten way easier; macrophytes have to be conditioned first, or they must die first and be turned to detritus for bact
recall that emergent macrophytes want to be tall and stalked to maximize light received. what implications may this have for organisms that want to eat them?
tall + stalked = lots of cellulose and other organic carbon
–> cant consume it, gotta wait for it to die
if we look at redfield ratios its like 500:24:1 compared to the normal 160:16:1
compared to emergent macrophytes, floating leaf species just float. what implications does this have for organisms that want to eat them?
lower carbon but since its so big, grazing isnt ‘easy’ - requires preconditioning
when talking about ppton, we discussed how intense cyanobacteria hold the community by the cock in eutrophic times. how do macrophytes play into this - consider it in terms of different types of macrophyte
emergent:
submerged: compete for CO2 in water column
floating: bc they float, they can outshade cyanobacteria (competition!)
what is the role of the boundary effect for SA:V
as things get closer (ex nutrients) there is a limited space for it to diffuse into the cell - diffusion is tempered by inherent boundary effect limitations
greater SA:V
