The Seafloor Section 1

Seafloor geography Continental shelf – the gradually sloping end of a continent that extends under the ocean – Atlantic coast – 100 km – 350 km into the sea – Pacific Coast – 10 km – 30 km – Ocean depth at continental shelf – avg. 200 m

Continental slope Extend from edge of continental shelf to the ocean floor Descends from 200 m to 4,000 m deep

Abyssal Plains Sediments constantly settle on the bottom filling in valleys creating flat seafloor called abyssal plains – Ocean depth at abyssal plain – 4,000 m to 6,000 m Seamounts – under-water inactive volcanic peaks

Volcanic Island Volcano that breaches the surface of the water forming an island

Mid-ocean Ridges The area in an ocean basin where new ocean floor has formed Forms due to oceanic plates moving apart and lava hardening

Subduction Zones Subduction zones are marked by trenches – long, narrow steep sided depression where one crustal plate sinks beneath another Mariana Trench 11 km ( 10,000 m) below sea level (deeper than Mt. Everest is tall)

Seafloor Mineral Resources 1 - Continental Shelf – petroleum and natural gas deposits – Sand and gravel can be dredged – Rivers deposit minerals that are concentrated in one place by ocean currents called placer deposit

2 - Deep Water Deposits Hot water comes out of cracks near mid-ocean ridges and quickly cools causing minerals to fall out Ex: sulfur, iron, copper, silver, zinc Hard to mine economically b/c so deep How would you mine them?

Section 2 Life in the Ocean

Photosynthesis Using energy from sun to produce energy Sun goes through water up to 100 m deep

Producers/Consumers Producers – org. that produce their own food – ex: algae, seaweed, kelp, phytoplankton Algae in oceans are an important source of oxygen Consumers – org. that eat (consume) producers – Ex: shrimp, fish, dolphins, sharks, killer whales

Food Chain/Food Web Org. transfer energy from one to another Ex: algae copepods herring cod seal killer whale

Chemosynthesis Org. such as bacteria that chemosynthesize or use sulfur to create energy

Reproduction Corals and sponges release reproductive cells into water for currents to distribute Others like salmon and sea turtle return to the same place each year to spawn or nest

Ocean Life Most org. live above continental shelf since most of food is located here b/c relatively shallow & sun passes to the bottom

Plankton Org. that drift with the current – Ex: algae and jellyfish Phytoplankton – producers – plants that drift Zooplankton – consumers – hatchlings, crabs, diatoms

Nekton Animals that actively swim – Ex: fish, whales Org. control buoyancy using air bladder Bioluminescence – luciferin molecule – used to attract bait, defense mechanism

Benthos Plants/animals living on the seafloor – Ex: sea cucumber, sea urchins, flounder, sea anemone, sponges

Beach Habitat Sand fleas/mole crabs, worms Makes holes in sand when water covers holes they filter feed Where sand is constantly covered – fish turtles horseshoe crabs Org. deal with lots of change

Rocky Shore Habitat Starfish, anemones, mussels, barnacles, attach to rocks Tide pools area where water remains during low tide – Good place to lay eggs b/c safe from predators

Estuary Area where mouth of a river opens into an ocean, lots of biological life Brackish water – fresh water & salt water mix Great place for hatchlings – many plants for protective cover and food Important economic food source Oysters, shrimp, clams, crab

Chesapeake Bay VA’s estuary Very easy to pollute b/c rivers flow directly in them Pollutants: – Pesticides, herbicides, insecticides, oil, biosolids, fertilizers

Coral Reefs Coral thrive in sunlit warm water Animal build hard calcium capsules around its body – Calcium from ocean Reef forms as org. connect to each other Other animals begin to live there

Section 3 Ocean Pollution

Pollution Anything not native to the environment that causes damage to org. by interfering w/ their life processes Oceans are environmentally and economically important Human activity have consequences for the ocean

Pollution Introduction 4 ways: – Deliberate dumping – Lost overboard accidentally – Air pollutants the enter through rain – Carried by rivers - runoff from lawns (herbicides), crop fields, construction sites (sediment)

Sewage Combined Sewage Overflow – Lynchburg Algal blooms – caused by fertilizers, sewage inc. amount of algae, algae dies, bacteria that decompose use up all oxygen, cause fish kills

Chemical Pollutants Pesticides, insecticides, herbicides Industrial waste contain heavy metals like mercury and lead, polycarbonated biphenyls (PCBs) biological amplification – when harmful chemicals can build up in the tissues of organisms that are at the top of the food chain

Oil Mostly from runoff of streets, parking lots, dumped into drains/ground Oil spills – use bacteria that eat oil and change its chemical composition called bioremediation

Solid Waste Balloons, plastic bags sea turtles eat mistaken for jellyfish Biohazardous waste – needles can make beaches unsafe

Sediment Forestry, construction, agriculture not practicing good erosion control techniques Sediment covers coral reefs & fill estuaries

Bathymetric Maps Isobaths – contour lines used to measure areas of equal depth