Phytoplankton Primary Production in the Western Antarctic Peninsula

 

The Palmer Long-Term Ecological Research (LTER) program studies an oceanic and coastal region along the Western Antarctic Peninsula - one of the most rapidly warming parts of our planet.  The program was originally started in the early 1990s in part to try to understand declining abundances of Adelie penguins in the region, although the LTER program studies the entire ecosystem.  Among other measurements, they have been measuring net primary productivity (NPP) to determine the total phytoplankton (algae) production in the euphotic zone (the sunlit upper region of the ocean).  These scientists measure NPP using a technique known as C-14 bicarbonate uptake.  Using this method, the scientists collect a sample of water from a specific depth in the ocean.  This water sample (including the natural phytoplankton and zooplankton communities) is put in a clear bottle and the scientists add some carbon-14 labeled bicarbonate (HCO3-).  Bicarbonate is the form of dissolved inorganic carbon that is most common in the ocean.  In other words, it is basically the form of carbon dioxide that is most available to phytoplankton.  So when the phytoplankton conduct photosynethesis, they must take up bicarbonate from their environment.  After the scientists have added the carbon-14 labeled bicarbonate they will place their samples in incubators on deck that are kept at natural light levels.  The phytoplankton will take up the carbon-14 labeled bicarbonate at the same time that they take up natural bicarbonate.  After 24 hours the scientists will end their experiment and filter all of the phytoplankton from the seawater.  They can then measure how much carbon-14 was taken up by the phytoplankton, because carbon-14 is radioactive.  This allows them to measure the NPP of the entire phytoplankton community.  The scientists make this data freely available and if you want to download it for yourself you can access it at the Palmer LTER DataZoo website.

 

The Palmer LTER scientists measure NPP at a site near the coast throughout the austral summer (this site is iced over for half of the year, making it impossible to sample during this period).  They also make a suite of other measurements, such as phytoplankton pigments, nutrient concentrations, and temperature.  I have compiled some of these other data in the excel spreadsheet below.  These measurements might be useful in trying to understand what drives variability in primary production in this polar region.

 

Please note that in this dataset the letters "NaN" means that a measurement was not taken.  Time-series evolve over time and logistical issues (e.g., 20-foot waves and 40-knot winds) can make it impossible to make every measurement every time.

 

Palmer Station Primary Productivity Data.xlsx

 

Data Columns:

 Year

 Julian Day

 Study = the name of the field season from which the data came

 Event = a number representing the unique sampling location and time

 Station = the station where the data came from ('B' is a near coast station)

 Depth = depth from which the sample was collected (unit = meters)

 Phosphate = the most abundant phosphorus-containing nutrient available to phytoplankton (unit = micromoles phosphate per liter of seawater)

 Silicic acid = the most abundant silicon-containing nutrient available to phytoplankton (unit = micromoles silicon per liter of seawater).  Note that only some phytoplankton (including diatoms) need silicon.

 Nitrite = a nitrogen-containing nutrient available to phytoplankton that is usually produced from ammonium during the process of nitrification (unit = micromoles nitrate per liter of seawater)

 Nitrate = the most abundant nitrogen-containing nutrient available to phytoplankton (unit = micromoles nitrate per liter of seawater)

 Ammonium = the most easily-utilized nitrogen-containing nutrient available to phytoplankton (unit = micromoles nitrate per liter of seawater).  Ammonium is given off by many heterotrophic bacteria and zooplankton.

 Chlorophyll a = the most important photosynthetic pigment found in nearly all plants and phytoplankton (unit = micrograms of chlorophyll per liter of seawater).  This column was measured fluorometrically.

 Phaeopigments = a byproduct of chlorophyll a that is most frequently created when zooplankton consume phytoplankton and the chlorophyll gets acidified in their guts (unit = micrograms of chlorophyll per liter of seawater)

 Particulate organic carbon = total amount of organic carbon containined in particles (unit = milligrams of carbon per meter cubed).  It is equal to the sum of the organic carbon in phytoplankton + protistan zooplankton + heterotrophic bacteria + dead organic matter

 Particulate organic nitrogen = total amount of nitrogen containined in particles (unit = milligrams of carbon per meter cubed).  It is equal to the sum of the nitrogen in phytoplankton + protistan zooplankton + heterotrophic bacteria + dead organic matter

 Peridinin = An "accessory" pigment that helps phytoplankton use wavelengths of light that are unavailable to Chlorophyll a.  Peridinin is most commonly found in diatoms.  Unit = micrograms peridinin per liter of seawater.

 19'-butanoyloxyfucoxanthin = An "accessory" pigment that helps phytoplankton use wavelengths of light that are unavailable to Chlorophyll a.  19'-butanoyloxyfucoxanthin is most commonly found in diatoms.  Unit = micrograms 19'-butanoyloxyfucoxanthin per liter of seawater.

 Fucoxanthin = An "accessory" pigment that helps phytoplankton use wavelengths of light that are unavailable to Chlorophyll a.  Fucoxanthin is most commonly found in diatoms.  Unit = micrograms fucoxanthin per liter of seawater.

 19'-hexanoyloxyfucoxanthin = An "accessory" pigment that helps phytoplankton use wavelengths of light that are unavailable to Chlorophyll a.  19'-hexanoyloxyfucoxanthin is most commonly found in diatoms.  Unit = micrograms 19'-hexanoyloxyfucoxanthin per liter of seawater.

 Divinyl chlorophyll a = A form of chlorophyll a that is most commonly found in Prochlorococcus.  Unit = micrograms divinyl chlorophyll a per liter of seawater.

 Chlorophyll a = the most important photosynthetic pigment found in nearly all plants and phytoplankton (unit = micrograms of chlorophyll per liter of seawater).  This column was measured by high-pressure liquid chromatography

 Percent Surface Irradiance = Intensity of photosynethetically-active radiation.  Unit = percent of irradiance at the sea surface

 Primary Production = net bicarbonate uptake by phytoplankton in samples incubated at natural light levels (units = milligrams of carbon per meter cubed of seawater per day)