Plot of increases in cell number vs time for cell dividing by binary fission = Growth Curve Logarithmic Growth N = No2 n N = No2 n Exponential Growth N = No2 n N = No2 n n = number of generations (doublings) required for a population at an initial cell density (No) to reach a specific higher cell density (N) n = (log Nt-logNo )/log2 log2 = When cell concentrations of 10 2 reaches 10 5 cells/Liter in 4 hrs, how many generations has passed? n =1 n = = (5-2)/0.301 = 9.67 generations (doublings) n = (log log 10 2 ) / 0.301= (5-2)/0.301 = 9.67 generations (doublings) What was the generation time (gt) or doubling time (Dt)? = Dt = 4 hours/ 9.67 generations (doublings)/ = 0.41 hrs ~ 25 minutes gt = Dt = 4 hours/ 9.67 generations (doublings)/ = 0.41 hrs ~ 25 minutes ADD TO YOUR NOTES Doublings per day = 24 h/gt = 24/0.41 ~ 58!

Lot Chl a concentration control urea NO3 NH4 Log cell density Compare pattern of growth based upon cell number vs biomass estimates over time Under LD, cell division is often phased to one time of day, with gt varying in a repeatable (predictable) pattern over time Here, in situ diatoms were incubated in collecction water plus one of 3 possible inorganic nitrogen sources were added. Do results indicate that N is limiting in the original sample? Which is the most limiting N source? need control expt to see growth in absence of extra nutrients max min max

Synchronous growth Nt1 Nto Another way of estimating growth rate is to calculate the rate of change in cell number or mass per change unit time (dN/dt), esp. to identify phased & highly dynamic growth rates Where dN/dt = i s the rate of change in cell number or mass per unit time&  = specific growth rate constant, usually expressed in values per day (D-1) dN/dt =  N To solve for   for any specific time interval, the differential dN/dt must be integrated between times t1 & t2 lnNt 2 - lnNt 1 =  (t 2 -t 1 ) Note: ln (natural exponential log) [lnNt 2 - lnNt 1]/ (t 2 -t 1 ) =  units (d   Exponential Growth dN/dt =  N N   = ln 2/ n, where n = number of generations units (d  

Continuous culture system (chemostat, cyclostat, turbidostat) differ from batch cultures in that nutrients are supplied to the cell culture at a constant rate, and in order to maintain a constant volume, an equal volume of cell culture is removed. This allows the cell population to reach a “steady state” (ie. growth and cell division where the growth rate and the total number of cells per milliliter of culture remains constant). 1. If flow rate removes cells as fast as they divide, then the cell concentration in the chemostat will stay the same and its gt = time it takes to completely replace the volume of medium in the chemostat once. 2. However, cell concentrations in chemostat can rise when the actual gt is faster than the gt predicted by setting the flow rate. 3. And cell concentrations in chemostat will fall when the actual gt is predicted than the gt predicted by the set the flow rate. Pattern of diel variation in cell division of diatom grown in a cyclostat (chemostat with LD cycle)

Fe concentration in growth media 4 diatom spp What is the experimental set up to get this data using batch cultures ? Growth rate is dependent upon many biological variables and comparison of growth rates under different conditions and between phytoplankton type show the great variability that any one variable may have on growth rate.

Temperature Regulation of microbial growth rates (k =  ) Winter SST Different races of a single specie of phytoplankton havve developed at each pole as ocean warmed and separated the specie into isolated niches.

Atlantic temperature section Falklands Greenland

Surface salinity Note how much Saltier the N. Atlantic is than N. Pacific Ocean Salinity regulation of microbial growth…not the different shapes of the different curves salt ponds Extreme halophile… salt ponds most marine phytoplankton halophile… most marine phytoplankton estuaries, coastal zone, ice edge halotolerant… estuaries, coastal zone, ice edge freshwater, soil, gut (enteric) Non-halophile… freshwater, soil, gut (enteric) Non-halophile Halophile Extreme Halophile Halotolerant

7. Sinking &/or Burying of POC in sediment Fecal material Review of the Carbon Cycle found in all types of aquatic ecosystems inorganic 1 1. Inorganic Nutrient Uptake & Limited availability controls u 2. Autotrophic Growth (formation of new organic C, N, P, S, Si etc. from external inorganic sources) / Plant Biomass /Animal Biomass /Bacterial Biomass 3. Grazing (consuming new POM, DOM ) and passing through food webs, microbial loops 5 5. Uptake of DOM to support heterotrophic growth 6 6. Remineralization DOM4 4. Create DOM pool due to excretion sloppy feeding, death / decay 3*. Grazing (consuming recycled POM, DOM ) and passing through microbial loops