aquatic life zones: 2 major categories

Aquatic Life Zones: 2 major categories

1. Marine (saltwater) Or 2. Freshwater

Types of organisms determined by:

• Salinity• Temperature• Sunlight availability• D.O. (dissolved oxygen)• Nutrient availability

Major types of Organisms

• Plankton: small free-floating

organisms

– Phytoplankton: plant-like• Photosynthetic• diatoms, protists, etc

- Zooplankton: animal-like • Heterotrophic• Protozoans• Larvae• Copopods, cnidarians, krill…etc.

- Ultraplankton: TINY (less than 2 micrometers)• includes bacteria

• Benthos (benthic organisms): bottom dwellers – anchor to one spot, burrow, or walk along bottom

• Nekton: active swimmers – don’t follow currents

Baleen whales: filter feedersPlates (baleen) hang from upper jaw – filter plankton from waterincludes: humpbacks and blue whales

Toothed whales: teeth used to bite and chew food

includes:orca (killer whale) and sperm whale

Marine Lifezone:

Subcategories: * Coastal * Open Ocean (Sea)

euphotic zonebathyal zoneabyssal zone

Subcategory: Coastal

• High tide to Continental shelf

• (Ample sunlight) high NPP

• 90% of all marine species

1. Coral reefs: MOST biodiverse areas of all aquatic life zones

– “The Aquatic Rainforest”– Hundreds of thousands of coral polyps

excrete CaCO3 skeletons

– Grow slowly, disrupted easily:• Biggest threat: sediment run-off

• Bleaching (even from 1 degree temp increase)

• Removal (aquariums/jewelry)• Pollution • Damage (tourists, anchors, natural

disasters)• Overfishing• Cyanide/dynamite “fishing”

–1 m2 of reef killed for every fish caught

2. Intertidal zone: shoreline between low and high tide

• Tides caused by gravitational pull of moon

• Organisms adapted to HARSH conditions

•

3. Barrier Islands: islands separated from the mainland by a shallow sound, bay, or lagoon

• Constantly shifting beaches due to erosion– Can be helped with a jetty

• Dunes – backbone that provides stability– Plants hold sand in place– Protect from natural disasters

4. Coastal wetlands: inlets, bays, sounds, Mangrove forest swamps

5. Estuary: where freshwater meets saltwater (mouth of a river)

Marine Lifezone:

Subcategories: * Coastal * Open Ocean (Sea)

euphotic zonebathyal zoneabyssal zone

Subcategory: Open Ocean 1. Euphotic zone: top

• Sunlight layer: phtyoplankton = photosynthesis: HIGH D.O. (dissolved oxygen) and low dissolved CO2, big fish and mammals

2. Bathyal zone: middle• Dimly lit – little/no producers, zooplankton,

smaller fish3. Abyssal zone: bottom • Dark, cold, little D.O., nutrients on floor• Chemosynthetic bacteria at hydrothermal

vents