Oceans

Ocean Water Chemistry The salinity of the water is on average 35 parts per thousand. This means that in 1kg of ocean water there is about 35g of salt. Sodium and chloride make up almost 86% of the ions dissolved in ocean water. Smaller amounts of other ions including magnesium, calcium, nitrogen, and phosphorus also exist in ocean water.

Variations of Salinity Rain, snow, and melting ice add fresh water to the ocean which lowers the salinity. Also, near the mouths of large rivers, the salinity is lower due to freshwater entering. Things that increase salinity would be evaporation or the water becoming ice because the salt is left behind to dissolve in the remaining water.

Effects of Salinity Salt in the water causes it to freeze at a much lower temperature. Saltwater has a higher density that freshwater. Seawater has greater buoyancy due to the higher density.

Other Ocean Properties The deeper you go into the ocean, the more dense and cooler the water gets. Carbon dioxide is 60 times more plentiful in the oceans as in the air. Algae use for photosynthesis Corals use it to provide the carbon for their hard skeletons

Other Ocean Properties cont. Oxygen is not as plentiful in seawater. Most plentiful in seawater near the surface. Comes from the air and photosynthesis from algae Cold waters in polar regions contain more oxygen than the warm tropical waters. Enough to support a variety of organisms. The deeper you go, the colder it gets. The deeper you go, the more pressure that is exerted on an object.

Currents and Climate Surface currents, which affect water to a depth of several hundred meters, are driven mainly by winds. Gulf Stream – largest and most powerful surface current in the North Atlantic Ocean Affect climate by moving cold and warm water around the globe Deep currents are caused by differences in density of ocean water

Currents and Climate cont Deep currents move and mix water around the world. They carry cold water from the poles to the equator. Upwelling Brings tiny ocean organisms, minerals, and other nutrients from the deeper layers of the water. Without this motion, surface waters of the open ocean would be very scarce in nutrients. Zones of upwelling using have lots of fish due to the nutrients being plentiful.

Exploring the Ocean Ocean has been explored for many years due to travel and food. Ocean floor is almost twice as deep as the Grand Canyon (3.8 kilometers deep on average) Major advance in ocean floor exploration was sonar (sound navigation and ranging) Must withstand cold and extreme pressure

Life in the Ocean Plankton – tiny algae and animals that float in the water and are carried by waves and currents (diatoms, copepods, larvae of some animals) Nekton – free-swimming animals that can move throught the water column (squid, most fish, whales, seals, etc) Benthos – organisms that inhabit the ocean floor (crabs, sea stars, octopus, lobsters, sea anemones)

Relationships Among Organisms Many plankton and benthos are algae. Like plants, algae use sunlight to produce their own food using photosynthesis. Photosynthetic plankton are called producers. Other plankton and benthos, as well as all nekton, eat either algae or other organisms which means they are consumers. Organisms that break down wastes and the remains of other organisms are called decomposers.

Food Web Plankton are a source of food for organisms of ALL sizes

Intertidal Zone From the highest high tide to the part exposed by the lowest low tide. Organisms that live in the rocky intertidal zone must be able to tolerate the pounding of the waves and changes in both salinity and temperature. They must withstand periods of being underwater and periods of being exposed to the air. The spray zone is never completely covered with water. Only gets splashed when the waves break.

Neritic Zone From low tide line to edge of continental shelf Kelp forests and coral reefs are found in the Neritic Zone Kelp forests – grow in cold neritic waters where the ocean floor is rocky Coral reefs – made of living things; can only form in shallow, tropical ocean waters; protect coastlines during storms Home to many things because the shallow water receives sunlight and a steady supply of nutrients washed from the land into the ocean.

Open Ocean Begins at edge of continental shelf Only a small part receives sunlight and water has fewer nutrients Divided into 3 zones Surface zone – extends as far as sunlight can reach below the surface, only part to receive enough sunlight to support growth of algae Transition zone – from bottom of surface zone to a depth of about 1km, darker and colder Deep zone – darker and colder that transition zone, few organisms live here, animals use bioluminescence to produce their own light Hydrothermal vents are in deep zone. Bacteria feed on nutrients and form base of food web at hydrothermal vent.

Creatures of the Deep

Yeti crab--Lives near hydrothermal vents

Glass squid

Hydrothermal vent snail—only one discovered

Copepod--Discovered 2006, 5k+ meters down, Atlantic, Pacific

New dumbo—discovered over mid-Atlantic ridge

Jeweled squid—above mid-Atlantic ridge—lives 500-2000 meters

Pink see-through fantasia is a swimming sea cucumber at 2500 meters

Fathead found during expeditions at 1013-1340 meters

squidworm

Pacific barreleye fish

Goblin shark

Spider crab

Coconut crab