Life in the pelagic realm: The Coastal and Open Ocean Flashcards
Where do coastal waters extend?
Edge of continental shelf (<200m) to the estuaries . 7% ocean surface, <0.5% ocean volume
What are the characteristics of coastal waters?
Most biologically productive, nutrient rich and have high primary production, major role in biogeochemical cycling (Organic carbon, CaCo3, SiO2, gas exchange flux of C and N, total global production, most total global production, new production, denitrification) most fisheries
What other processes occur in coastal zone which affect the physical characteristics?
Shallowness, freshwater flow, tidal currents, upwelling events
What happens to nutrients at the river/estuary interface?
River flows over the seawater and nutrients are trapped at the interface which causes phytoplankton bloom and upwelling occurs
What causes river and estuarine plumes?
Increased turbidity and nutrient enrichment from materials carried by the river (particles, river-born nutrients), nutrient enrichment from entrainment and upwelling of nutrient-rich seawater, enhanced water column stability due to less dense freshwater layer over the denser ocean water layer
Why are estuaries important?
Very productive (lots of phytoplankton), nursery grounds for many species, economically relevant, salt-marshes and mangrove swamps
What are the characteristics of the North Atlantic?
Warmer (8.5C in winter), low nutrient levels in summer, no iron limitation (HCLN), lots of diatoms and photosynthetic dinoflagellates
What are the characteristics of the North Pacific?
Cold (3.8C in winter), high nutrient levels year round, iron limited (HNLC), lots of small photosynthetic flagellates, lots of microzooplankton
What is Line P?
A series of ocean weather sampling stations in the subarctic NE Pacific with 60 years of data
What is the difference between the NA copepod and NP copepod species?
NA migrates from surface to 500m depth several times throughout the year, deep water in winter, NP migrates to surface in spring/early summer, then migrates to 500m as an adult and for spawning
What are the ecosystem characteristics of NA?
Poor coupling of phyto. and zoo. cycles during growing season, high export of phytoplankton, large number of benthic fishes
What are the ecosystem characteristics of NP?
Close coupling of phyto. and zoo. cycles during growing season, low export of phytoplankton, larger number of pelagic fishes
What are the 2 study sites with long time-series of observations in subtropical gyre biomes?
HOTS (Hawaii), BATS (Bermuda)
What are characteristics of subtropical gyres?
Anti-cyclonic motion, convergent, surface layer 18C winter, 25C summer, season thermocline (50-70m), permanent thermocline (125m), water column stability, high nutrients below pycnocline, low/undetectable above
What are the rates of photosynthesis and nutrient concentration changes like in subtropical gyres?
Net PS positive to 125m, surface nitrate depleted up to that depth, surface phosphorous not quite depleted, oligotropic biomes, uses regenerated nutrients, deeper chl maximum
Why is there a low chl maximum in subtropic gyres?
Low vertical mixing of nutrients upwards through pycnoline, 60% phytoplankton biomass at depth is cyanobacteria (Prochlorococcus)
What adds N2 to subtropical gyres?
N2 fixation by Trichodesmium and other cyanobacteria (mostly in Sargasso Sea)
What supples Fe in Sargasso Sea?
Aeolian dust from North Africa which supports N2 fixation, then P becomes exhausted
What is the ratio of N:P in Sargasso Sea and NPCG?
Sargasso Sea: 17:1, NPCG: 15:1 due to differences in N2 fixation
What does grazing due?
Keeps production almost exactly in balance by consuming all increase in biomass
What are the characteristics of NPCG/Sargasso mesozooplankton?
Continuously active, no seasonal rest phase, diverse but present in low biomass
What are the normal conditions for the Western equatorial pacific?
Low pressure and rising air, cloudy and rainy
What are the normal conditions for the Eastern equatorial pacific?
High pressure and sinking air, clear and dry weather?
What do pressure differences between WEP and EEP do?
Cause strong SW trade winds which move water from E to W and upwelling along Peruvian coast and PAcific warm pool on western Pacific
What is ENSO?
Irregular shift in ocean/atmosphere characteristics every 2-10years
What are the effects of ENSO?
Alternation between warm and cold phases (12-18months/years) in atmosphere/ocean, strong local effects (productivity, fisheries yield, marine mammals and birds, weather patterns), global climate, benefits and consequences
What happens during el nino?
Warmer temperatures
What happens during la nina?
Colder temperatures
What is the ENSO index?
Index determining whether we are in El Nino or La Nina. Calculated using weighted average of atmospheric/oceanic factors (atmospheric pressure, winds, sea surface temperatures)
What are the effects of mild and severe el nino?
Mild: affects only equatorial SP, Sever: alter atmospheric jet stream and weather worldwide. Drought (W), forest first, coastal erosion, marine impact, flood (E)
What is TAO?
Monitors equatorial pacific with ~70 moored buoys with realtime data to detect and understand el nino and la nina
When do La Nina’s occur relative to El Nino’s?
Usually the year after
What are the conditions in La Nina?
Cooler temperatures, weaker winds,
What ENSO index indicates strong El Nino or La Nina?
2 (El Nino), -1.5 (La Nina)
What is the dominant copepod in the North Atlantic?
Calanus finmarchicus
What is the dominant copepod in the North Pacific?
Neocalanus plumchrus,
