Stream Bio Unit 2

primary production

production of organic C molecules from CO2, primarily via photosynthesis

liebig’s law of minimum

growth is controlled by the scarcest resource

redfield ratio

plants require C:N:P of 106:16:1

FPOM

fine particulate organic matter; comes from fragmented leaves, feces, eroded soil, and microbes

DOM

dissolved organic matter; mostly carbon, but also includes N and P (DON, DOP); main sources are leaf and soil leaching; masses through a 0.45microm filter

atochthis

meaning “from the river”; comes from organisms in the river

throughfall

organic matter is leached off of plants during precipitation, then enters the stream

labile DOM

simple, low molecular weight compounds are highly soluble and rapidly assimilated; can easily be respired into CO2; includes simple carbohydrates or amino acids

recalcitrant DOM

high molecular weight compounds with low solubility are poorly assimilated; require enzymes to enact decomposition and impart color into water; commonly come from terrestrial matter like leaves; includes humic acids, phenols, lignin, and carboxylic acids

autotroph

organism that can fix inorganic C into organic carbon

heterotroph

organism that obtains organic carbon from outside sources

autochthonous

carbon originating inside the stream

allochthonous

carbon from outside the stream

ecosystem/community respiration (CR/ER)

respiration of C by all stream organisms (dec. oxygen); occurs by both heterotrophic (Rh) and autotrophic (Ra) organisms; always a negative number bc it’s a loss of carbon

gross primary production (GPP)

production of new organic C by autotrophic organisms (inc. oxygen); always a positive value bc it’s a gain of carbon

net primary/ecosystem production (NPP/NEP)

new organic C produced by autotrophs in excess of respired C; can be positive or negative

reaeration

a physical process pushing DO towards equilibrium with the atmosphere

GPP to ER (P/R) ratio

indicates the importance of autochthonous v. allochthonous sources of C; >1 means energy sources are dominated by autotrophic production, <0.5 means energy sources are dominated by allochthonous inputs, and 0.5-1 means a mix of internal and external C

gathering collectors

feed on fine particles in depositional areas of streams; often the dominant FFG in streams; rely on low-quality food = slow growth rates and lots of consumption

ecosystem engineers

organisms that greatly modify the environment changing the amount, quantity, or type of habitat; affect community structure and food webs disproportionately to the size of the population