I. I.Zonation C. C.Depth Zones 2. 2.Benthic c. c.Sublittoral (Mean low water to edge of continental shelf) Region of sea floor underlying neritic zone

I. Zonation

C. Depth Zones2. Benthic

c. Sublittoral (Mean low water to edge of continental shelf)• Region of sea floor underlying neritic zone (8%)• Character of zone changes with depth and distance

offshore: concentrations of benthic algae decrease, hard substrate replaced by soft substrate

• Highly productive; supports higher densities of organisms than deeper zones

• Vast majority of large benthic species live in this zoned. Bathyal (200–4000 m)

• Essentially no primary production• Organismal densities decrease with increasing depth• Within this zone, physical parameters change

dramatically: light availability, temperature, [O2]• Covers 16% of sea floor

I. Zonation

C. Depth Zones2. Benthic

c. Abyssal (4000-6000 m)• Largest ecological region on earth• Covers 75% of sea floor (>50% of earth’s surface)• Light virtually absent, pressure high, cold, food scarce

and somewhat unpredictable in space & time• Organisms difficult to study and poorly known,

compared to shallow-living relatives

d. Hadal (6000–11,000 m)• Oceanic trenches• Trenches may accumulate organic detritus (food) that

may form basis of trench food webs• Organisms difficult to study and not well known

II. Ocean Circulation

A.A. Surface CurrentsSurface Currents• Driven by winds

• Surface currents deflected to right/left of wind direction by Coriolis Effect

• Anticyclonic gyres in major basins• Clockwise in N. Hemisphere• Counterclockwise in S. Hemisphere

Fig. 4-14

Fig. 4-15


A.A. Surface CurrentsSurface Currents• Driven by winds

• Surface currents deflected to right/left of wind direction by Coriolis Effect

• Anticyclonic gyres in major basins• Clockwise in N. Hemisphere• Counterclockwise in S. Hemisphere

• Currents transport heat from equator to poles• Why is Antarctica covered with ice today?

• Surface temperatures higher on western margins of ocean basins vs. eastern margins


B. Vertical Circulation• Thermohaline circulation

• Driven by unstable water column with denser water at surface

• Drives Great Ocean Conveyor

Fig. 4-16


B. Vertical Circulation• Thermohaline circulation

• Driven by unstable water column with denser water at surface

• Drives Great Ocean Conveyor

• Upwelling and Downwelling• Driven by wind

Fig. 4-22

III. Marine Microbes

A. Marine Viruses• Not alive in traditional sense

B. Marine Bacteria• Organized by nutritional mode and taxon

C. Archaea• “Extremophiles”

D. Eukarya• Fungi• Stramenopiles• Haptophytes• Alveolates• Choanoflagellates• Amoeboid Protozoans

Fig. 6-1


A. Marine Viruses• Virion outside of host cell• 10x as abundant as marine bacteria

• Up to 1010 virions per liter

• DNA or RNA encapsulated in protein capsid• DNA viruses

• Helical tail• Two basic life cycles: lytic, lysogenic• Ecologically important

• Facilitate breakdown of microbial blooms• Alter food/nutrient availability• Cause diseases in marine animals

Fig. 6-3

Fig. 6-2







Fig. 6-4








B. Marine Bacteria• Many shapes - spheres, coils, rods, ringsMany shapes - spheres, coils, rods, rings• Very small cells (usually less than 1 μm across)Very small cells (usually less than 1 μm across)

• May be very large (by bacterial standards)

Fig. 6-5

Coccus Bacillus Spirillum


B. Marine Bacteria1. Autotrophic

a. Photosynthetic• Energy from sunlight• Contain chlorophyll or other photosynthetic pigments• Important primary producers in open oceani. Cyanobacteria (aerobic) – Some perform nitrogen

fixationii. Purple and green photosynthetic bacteria (anaerobic)

b. Chemosynthetic• Obtain energy from chemical compounds• Ex: Hydrogen, hydrogen sulfide, ammonium ion• Often anaerobic, may be symbiotic

2. Heterotrophic• Most are decomposers (break down organic material)• Important in nutrient cycling• May be symbiotic

Fig. 6-8







Fig. 6-11







Fig. 6-14


C. Archaea• Resemble bacteria superficially but may be more closely

related to eukaryotes than bacteria• Very small cells (0.1 – 15 μm)• Heterotrophs or autotrophs (photo- or chemosynthetic)

• Many methanogens• Some fix nitrogen

• Important decomposers• Abundant in sediments

• Extremophiles• Deep sea (barophiles)• Hydrothermal vents (thermophiles)• Salt ponds/lakes (halophiles)• Antarctic (psychrophiles)• Acid/Alkaline lakes (acidophiles)


D. Eukarya1. Fungi

• Unicellular or multicellular (produce hyphae)• Body = mycelium• Mostly microscopic

• Cell walls made of chitin• Heterotrophic

• Important decomposers, esp. of wood• Some pathogenic forms• Host to algae in lichens

Fig. 6-17


D. Eukarya2. Stramenopiles (Heterokonts)

• Diverse group• Bear two different flagella at some point in life cycle

• One complex with mastigionemes• Photosynthetic and nonphotosynthetic forms

• Photosynthetic = Ochrophytes

a. Diatoms

b. Silicoflagellates

Fig. 6-18



a. Diatoms• Unicellular; may form chains• Cell enclosed by silica frustules (test)• Shape: centric or pennate• Test usually perforated and ornamented with

spines or ribs (Why?)• Perforations allow gases, nutrients, waste

products to pass through test to cell• Important open-water primary producers,

especially in temperate and polar regions

Centric

PennateFig. 6-19

Fig. 6-20



b. Silicoflagellates• Silica test, usually with spines• One or two flagella• Especially abundant in• cold water

Fig. 6-21


D. Eukarya2. Haptophytes

• Two similar simple flagella

a. Coccolithophores• Covered by calcium carbonate coccoliths• Abundant and important in tropics• Coccoliths may be important in sediments

Fig. 6-23

Fig. 6-24


D. Eukarya3. Alveolates

• Membranous sacs (alveoli) beneath cell membranes

a. Dinoflagellates

b. Ciliates

Fig. 6-25



a. Dinoflagellates• Motile forms possess two flagella• Some lack flagella• May be autotrophic, heterotrophic (~50%),

mixotrophic• Some symbiotic (e.g. zooxanthellae)

• Two basic forms• Thecate – Covered with theca made of cellulose

plates, sometimes with spines (Why?)• Athecate – Less common

Fig. 6-26



b. Ciliates• Important small heterotrophs

Fig. 6-27


D. Eukarya4. Choanoflagellates

• Solitary or colonial free-living heterotrophs• Best-known from surface waters• Important grazers on bacteria• Closest living relatives of metazoans

Fig. 6-28


D. Eukarya5. Amoeboid Protozoans

a. Foraminiferans• Test (shell) made of calcium carbonate (CaCO3) or

agglutinated sediment particles - Fossil tests used to age geological deposits

• May have multiple chambers - Tests increase in size as organism grows

• Feed by extending pseudopodia through pores in test - Trap bacteria and other small organisms/detritus - Some have bacterial symbionts

• Pelagic forms (calcareous) - Often have spines - Tests may form foraminiferan oozes, esp. in shallow water beneath tropics

• Benthic forms (calcareous or agglutinated) - Calcareous tests can be important sources of sand for beaches

http://earthguide.ucsd.edu/earthguide/imagelibrary/orbulinauniversa.html

http://www.ucl.ac.uk/GeolSci/micropal/foram.html


D. Eukarya5. Amoeboid Protozoans

b. Radiolarians• Test made of silica (SiO2)

• Tests may form radiolarian oozes, esp. in deep water in temperate and polar regions

• Feed by extending pseudopodia through pores in test

• Trap diatoms and other small organisms/detritus (Why diatoms?)

Fig. 6-30

Documents

I. I.Zonation C. C.Depth Zones 2. 2.Benthic c. c.Sublittoral (Mean low water to edge of continental shelf) Region of sea floor underlying neritic zone