Ocean Water and Ocean Life

Chapter 15

SalinityThe total amount of

solid material dissolved in water.

Measured in Parts Per Thousand (ppt ‰)

Average Ocean Salinity = 35‰Most of the salt in

seawater is NaCl, or common table salt.

Where did the salt come from??Chemical

weathering and erosion of rocks and minerals.

Earth’s interior:Gases emitted into

the air by volcanoes throughout geologic history

Processes that Affect SalinityLess salty

PrecipitationRunoffMelting ice

More saltyEvaporationFormation of ice

Temperature and ThermoclineOcean temperature

is highest at the surface.

Thermocline- the layer of ocean water where there is a rapid change of temperature with depth.Creates a vertical

barrier for ocean life.

DensityMass per volume

unitMass ÷ VolumeAffects water’s

vertical position.Factors that affect

density:SalinityTemperature

Ocean LayersMixed Zone –water is mixed

by waves and circulation currents and tides

Transitional Zone –temperature falls abruptly

Deep Zone –Little to no sunlight. Density is the same as well as temperature.

Ocean Floor

Classification of Marine Organisms Classified by

where they live and how they move.

Plankton: float or drift with ocean currents.

Nekton: free swimmers found in all area of the ocean.

Benthos: Live on ocean floor

Marine Life Zone FactorsAvailability of

sunlight.Distance from shoreWater depth

Photic vs. Aphotic zonesPhotos=lightPhotic Zone: upper

part of the ocean where light can penetrate.Euphotic: portion of the

photic zone where there is enough light to support photosynthesis.

Aphotic Zone: no sunlightDeep ocean

Distance from shoreIntertidal zones:

Area where land and ocean meet and overlap.

Neritic Zone: Seaward from the

low-tide line to the continental shelf break.

Oceanic Zone-Beyond the

continental shelf.

Depth of OceanPelagic Zone

Open ocean of any depth.

Benthic zoneAny sea-bottom surface

at any distance from shore.

Abyssal zoneDeep area with high

pressure zones, low temps and low oxygen levels.

Ocean ProductivityPrimary Productivity is

the production of organic compounds from inorganic substances .

Photosynthesis- uses light energy to convert water and carbon dioxide into glucose.

Chemosynthesis- uses chemical energy to create organic molecules from inorganic nutrients.

Factors that Affect a Region’s Photosynthetic ProductivityAvailability of

nutrients

Amount of solar radiation/sunlight.

Productivity in the OceansProductivity in Polar Oceans

Productivity in Tropical Oceans

Productivity in Temperate Oceans

High amounts of nutrients

Small amounts of nutrients

Winter: Low productivity. Days are short and sun angle is high

Small amounts of sunlight

High amounts of sunlight

Spring: Phytoplankton quickly depleted. Productivity is limited.Summer: Strong thermocline develops so surface nutrients are not replaced.Fall: Nutrients are near surface when waters are being mixed due to winds.

Trophic LevelsA trophic level is a nourishment level in a

food chain. • Top of the pyramid

Tertiary

Consumers:

• Consume the herbivores.

Carnivores or secondary consumers.

• Consume the producers

Herbivores or primary consumers.

• Lowest levelProducers/Autotrophs

Food Chain vs. Food WebFood Chain:

sequence of organisms through which energy is transferred, starting with the primary producer.

Food Web: group of interrelated food chains