Marine Ecology Flashcards
What affects O2 distribution in the ocean
Eutrophication and global warming
Describe the relationship between solubility of O2 and temperature
The concentration of dissolved oxygen when in equilibrium with the atmosphere decreases with increasing temperature
Where/how is O2 produced in the ocean
In sufficiently light surface waters phytoplankton photosynthesize
Where/how is CO2 produced in the ocean
Throughout the watercolumn by respiring organisms
Define thermocline
The transition layer between the warmer mixed water of the epipelagic zone and the colder deeper mesopelagic zone
Describe the vertical distribution of dissolved O2
In surface mixed layer Equilibrate with atmosphere Production through photosynthesis Loss via respiration Below thermocline Can’t equilibrate with atmosphere Loss via respiration Supply via circulation
What is an oxygen minimum zone?
a zone where O2 saturation is at its lowest
What causes oxygen minimum zones
When water renewal very slow and/or
respiration very high
Define oxycline
a sharp gradient in oxygen
Describe the Oxic level
~ 250-300 mmol O2m-3 Normal aerobic respiration takes places
Describe the Hypoxic level
~ 60 mmol O2m-3 – fish, zooplankton stressed and actively select higher oxygen levels
Describe the suboxic level
5-20 mmol O2m-3. Denitrification : consumes nitrate, produces nitrogen
reduced zooplankton egg development
Describe the anoxic level
oxygen minimum zones and sediments). Sulphate reduction, production of hydrogen sulphide. Methane production from CO2
What is eutrophication and its consequences?
Run of of nitrates and phosphates leading to algal blooms which reduces the O2 concentration potentially leading to hypoxic conditions. Nutrient pollution is the single largest pollution problem affecting coastal waters of the United States (Howarth et al., 2000).
What two effects does global warming have on the oceans
Decreases solubility and increases stratification
What are the consequences of global warming on phytoplankton
Surface warming increases the density difference, or vertical“stratification” of the ocean waters, leading to
less mixing between the surface water layers,
where phytoplankton live, and the deeper water
layers, which contain the nutrients they need to
flourish.
What are the 3 oceanic consequences of rising CO2 level?
acidification, warming and deoxygenation