Increased Temperatures and Marine Protist Productivity

Increased Temperatures and Marine Protist Productivity : 

Increased Temperatures and Marine Protist Productivity By Tom Tran Biology 7 Section 7419 December 1, 2011

Abstract : 

Abstract Marine phytoplankton and protists contribute to almost half of the biosphere’s net primary productivity (NPP) through photosynthesis. About 30% of the world’s photosynthesis is carried out by diatoms, dinoflagellates, multicellular algae, and other aquatic protists. Photosynthesis is a vital link in the cycling of carbon between living and inorganic stocks as more than a hundred million tons of carbon in the form of CO2 are fixed into organic material. The trends of sea surface temperatures (SST) and NPP are correlated with each other, inversely.

Introduction: The Ocean and Protists : 

Introduction: The Ocean and Protists Over 71% of the surface of the Earth is covered with ocean areas. Marine phytoplankton and protists are the primary producers and the foundation of the ocean food chain as well as the terrestrial as they produce organic compounds and oxygen. Essential nutrients such as nitrogen, phosphorous, silicon, and iron are attained by the producers through the circulation and upwelling of colder, nutrient-dense waters from the lower zones of the ocean. Nutrients pass through the food chain and are reused as they complete their cycle going through the bottom of the ocean to the light-rich layers to eventually be consumed and recycled in some form.

Introduction: Measuring Protistan Productivity : 

Introduction: Measuring Protistan Productivity Warmer layers of water prevent protists and phytoplankton from surviving and producing, thus leading to less density. Measuring the density of marine protist populations as well as their NPP output requires scientific systems, programs and instruments installed on orbiting satellites. To help with comparing climatic variability, the Multivariate ENSO Index (MEI) is used. A mathematical model is also used to give estimates on global NPP for the recorded data obtained from the satellites’ instruments.

Materials and Methods: Instruments on Satellites : 

Materials and Methods: Instruments on Satellites Sea-viewing Wide Field-of-view Sensor (SeaWiFS) on Geoeye’s Orbview-2 satellite. Advanced Very High Resolution Radiometer (AVHRR) sensor on the National Oceanic and Atmospheric Administration’s (NOAA) series of orbiting satellites named NOAA-#-AVHRR. SeaWiFS equipped satellite NOAA satellite

Materials and Methods: Models and Indexes : 

Materials and Methods: Models and Indexes The Multivariate ENSO Index is used to evaluate the cycles of El Niño/Southern Oscillation weather phenomenons based on factors of sea-level pressure, surface winds, sea surface temperatures (SST), surface air temperatures, and cloudiness. Anomalies in graphs are found by taking the average of the entire time series and deducting that from each monthly average. The Simple Ocean Data Assimilation(SODA) is used to record stratification anomalies and density data. The estimations of NPP from satellite chlorophyll data is given through a math model called the Vertically Generalized Production Model (VGPM). This model is used to give estimates for the SeaWiFS record and data.

Materials and Methods: Data sources : 

Materials and Methods: Data sources SeaWiFS data: http://oceancolor.gsfc.nasa.gov MEI data: http://www.cdc.noaa.gov/people/klaus.wolter/MEI SODA data: http://www.atmos.umd.edu/~ocean AVHRR data: http://podaac-www.jpl.nasa.gov/sst

Results:Figure 1: Distribution and trends in global ocean NPP and chlorophyll concentrations : 

Results:Figure 1: Distribution and trends in global ocean NPP and chlorophyll concentrations In figure 1a, the projection of Earth depicts various levels of NPP and the area in-between the two brown lines are areas where warm stratification exists. In figure 1b, the green line shows anomalies for chlorophyll concentrations. The gray dots and black lines (best fit lines) show anomalies for chlorophyll concentrations in stratified regions. In figure 1c, The green line shows anomalies of NPP levels and the gray dots and best fit lines show anomalies for NPP in stratified regions.

Results:Figure 2: Ocean productivity and NPP levels are closely tied to changes in climate conditions. : 

Results:Figure 2: Ocean productivity and NPP levels are closely tied to changes in climate conditions. In figure 2a, the grey symbols represent the NPP anomalies in stratified regions similarly to the previous figure. The red symbols represent the MEI of climate variability. In figure 2b, the grey symbols also represent the NPP anomalies in stratified regions. The red symbols depict the anomalies in ocean stratification and warm water layering that results in obstruction Note: The values for the MEI and stratification anomalies are reversed.

Results: Figure 3: The relationship between NPP and SST is inversely related as climate changes affect productivity : 

Results: Figure 3: The relationship between NPP and SST is inversely related as climate changes affect productivity Figure 3a shows global changes in SST in degrees Celsius from 1999 to 2004. Figure 3b shows the global changes in NPP in percentage from 1999 to 2004. Figure 3c shows that approximately 74% of the stratified regions have inversely related NPP and SST. Yellow and purple show decreasing NPP, but increasing and decreasing SST respectively. Red and blue show increasing NPP, but increasing and decreasing SST respectively.

Discussion and Conclusion : 

Discussion and Conclusion Upwelling and circulation of nutrient-rich waters can be disrupted by a warmer, stratified region of water. The warming of oceans affects productivity of marine protists as shown in figure 3. Comparing NPP and SST shows that they are inversely related and warmer waters cause a decline in productivity. Continuous periods of warming can be detrimental for the higher trophic levels of the food chain and the food web overall as the autotrophic producers are the base of the food chain. Marine protists such as diatoms and dinoflagellates can alter the nutrient cycles through a deficit of ocean detritus and coral reef development as dinoflagellates are symbiotic with the polyps that form the coral.