EPS SCI 15 Lecture 10 Review

Life is subdivided into three domains:

Eukaryotes, Bacteria and Achaea

Bacteria and Archaea:

have no cell nucleus and are called Prokaryotes

(Eukaryotes have a cell nucleus)

Prokaryotes

Single-cell organisms

Eukaryotes

Can be single-cell organisms (Protists) and multicellular organisms (with diversified cells)

Depending on the carbon and energy source, organisms are metabolically divided into:

photoautotrophs, chemoautotrophs, photoheterotrophs, and chemoheterotrophs.

Photosynthesis:

Takes up CO2 and water to build sugar and release oxygen

Respiration:

Consumes oxygen and sugars to produce CO2 and water

The ocean is subdivided into different habitable zones:

1. pelagic (in the water)

2. benthic (on/in the seafloor)

3. neritic (on the shelf)

4. oceanic (off the shelf)

5. photic (light)

6. aphotic (no light)

7. litoral (shelf tidal zone)

8. sublitoral (shelf below tidal zone)

Organisms in the ocean are subdivided depending on their lifestyle and habitat:

1. plankton (drifting in water)

2. nekton (actively swimming in water)

3. neuston/pleuston (at the water/air interface)

4. benthos (at the sediment/water interface)

Plankton comprises primary producers _______________ and consumers __________________ and can be categorized in different size spectra from femto (viruses <<μm) and pico (procaryotes and very small algea ~μm) to mega plankton

( e.g. salp chains up to some meters).

1. primary producers: phytoplankton = photoautotrophs

2. consumers: (zooplankton = chemoheterotrophs)

Trophic levels describe:

the position of an organisms in a food chain/web.

The basis of the (surface) ocean food chain starts with:

photoautotrophic bacterio- and phytoplankton, which is consumed by heterotrophic zooplankton. Together they form the plankton. Further up the food chain we find nekton (fish etc.) that feed on the zooplankton. Because some nekton also feeds on phytoplankton, trophic levels in the oceans are best described in webs rather than in chains.

Phytoplankton uses _____________ (blue and red wavelengths) with the chlorophyll pigment to conduct photosynthesis.

the light of the sun

Phytoplankton is ________________________________________________. For example, some form carbonate shells, others produce toxins and others are able to fix nitrogen (N2).

diverse also with regard to other chemical specialties

 Primary productivity can be inferred from:

1. satellite images of chlorophyll distribution

2. by dark/light incubations of seawater with organisms (measuring oxygen production/consumption).

At the compensation depth photosynthesis equals:

respiration

At the critical depth, photosynthesis integrated over the entire water column equals:

their total respiration

Primary productivity (= photosynthesis) of phytoplankton is limited0 by:

the penetration of light into the ocean.

Different parts of the light have:

different penetration depths into water (blue deepest, red shortest in clear water).

Light penetration into the ocean can vary by

(a)

(b)

(c)

(a) amount of particles in the water that absorb/reflect light

(b) seasonality (particularly at high latitudes)

(c) sun vs. moon light.