Phytop l anktonNutrien t sZoopla nktonPatterns of Productivity• There is a large “SpringBloom” in the NorthAtlantic (temperatelatitudes… remember theGulf Stream!)What is a bloom?• Analogy to terrestrial plants, referring tothe “spring blooming” of flowers• Typically short-lived, days to weeks(however, exceptions exist, such as theTexas Brown Tide, which lasted 7years)• Defined as a “significant” populationincrease… modeled after diatombloomsDiatom Blooms• Well studied--thought to be causedprimarily by 1) increase in nutrients,and/or 2) decrease in grazing pressure,with 3) appropriate physical conditions• Other (non-diatom) species oftenthought of as “rogue”, episodic, orinconsequential eventsModern Definition:• Non-Toxic species:– A “significant” increase in biomass with time,relative to the mean– >100 µg Chl L-1 in coastal waters– Deep Chlorophyll Maximum (is this a bloom?)• Harmful species:– Measurable harmful impacts, regardless ofcolor, toxicity, cell abundance, etc.Large-Scale VariabilityUpwellingIslandEffectDomesGyresIron FertilizationBloomsDefinitionsHNLCOligotrophicEutrophic: High ProductivityMesotrophic: ModerateOligotrophic: Low Prod.HNLC: High Nutrient, Low ChlWhat controls the large scale patterns?We would expect that it is some combination of Light,Temperature, Nutrients (bottom up control), and grazing(top down control)…..Major Ocean BasinsProvides no information about the biology!Large Marine Ecosystems of the WorldPatterns of ProductivityPatterns of ProductivitySpecies Succession is embedded within the “bloom”• can be differentspecies of thesame group (e.g.diatoms), ordifferent groups(e.g. diatoms-->dinoflagellates)or even different“strains” of onespecies….Patterns of Productivity1) Upwelling, Mixing2) Vertical Migration3) Direct Fixation4) Exogenous Inputs5) “Rogue Diatom” HypothesisSources of NutrientsWhy is the Spring Bloom in the North Pacific “missing”?N. Pacific--the Bering Seablooms, but the rest of the North Pacific is low in biomassN. Atlantic--widespread bloomingof phytoplankton throughout thebasin, not just near landLatitudinal Effects• Very High Lat,not enough light• Very Low Lat,not enoughvariability• N Atlantic, NPacific, shouldget two bloomsN Pacific vs. N AtlanticBehavior: Multiple DaysMigration by Growth StageCopepods produce eggs as a functionof:Water TemperatureTime of YearAvailability of PreyEgg production occurs mostly at night,when at depthDevelopment of early stages at depth isadvantageous because:Fewer predatorsCan’t swim yetMinimizes advective lossesWhat about Iron?-The deep concentrations ofiron are very similar in theNorth Pacific and NorthAtlantic (bottom panel), butthe surface concentrationsare very low in the NorthPacific compared to the NorthAtlantic (top panel)http://www-paoc.mit.edu/cmi/applications/biogeochemical.htmEcumenical Iron Hypothesis:1) In the North Atlantic, Iron is not limiting, but in the NorthPacific, Iron is limiting to diatoms--smaller cells are less ironlimited, but are heavily grazed2) In the North Atlantic, there is very deep winter mixing(NADW forms); In the North Pacific, there is no deep waterformation.3) In the North Atlantic, zooplankton “bloom” after thephytoplankton, but in the North Pacific, zooplankton arepresent all year.4) Iron limits diatom growth in the N. Pacific, and the4) Iron limits diatom growth in the N. Pacific, and themacro- and micro-zooplankton control the limitedmacro- and micro-zooplankton control the limiteddiatom blooms and blooms of other organisms!diatom blooms and blooms of other organisms!Is the ocean changing?Is the ocean changing?Is the ocean changing?Is the ocean changing?Other Mesoscale PatternsBesides global warming, there are other patterns thatimpact the oceans, and therefore biologicaloceanography:• Long time scales: glacial-interglacial cycles• 40-50 year time scales: Pacific DecadalOscillation• Newly recognized: North Pacific Gyre Oscillation• 5-7 years: El Niño Southern Oscillation• 0-3 years: mesoscale eddies• Infrequent: warm and cold anomalies- Caused by fluctuations in Jet Stream (US)- Most recent, 2005 warm anomalyAll of these can make it difficult to interpret short termrecords, and can look like global warming!ENSOOther Mesoscale PatternsBesides global warming, there are other patterns thatimpact the oceans, and therefore biologicaloceanography:• Long time scales: glacial-interglacial cycles• 40-50 year time scales: Pacific DecadalOscillation• Newly recognized: North Pacific Gyre Oscillation• 5-7 years: El Niño Southern Oscillation• 0-3 years: mesoscale eddies• Infrequent: warm and cold anomalies- Caused by fluctuations in Jet Stream (US)- Most recent, 2005 warm anomalyAll of these can make it difficult to interpret short termrecords, and can look like global warming!Biological ModelsParadox ofthe