Ocean Water and Ocean Life Chapter 15

Salinity The 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 Salinity Less salty Precipitation Runoff Melting ice More salty Evaporation Formation of ice

Temperature and Thermocline Ocean 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.

Density Mass per volume unit Factors that affect density: Mass ÷ Volume Affects water’s vertical position. Factors that affect density: Salinity Temperature

Ocean Layers Mixed 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 Factors Availability of sunlight. Distance from shore Water depth

Photic vs. Aphotic zones Photos=light Photic 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 sunlight Deep ocean

Distance from shore Intertidal zones: Neritic Zone: Oceanic Zone- 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 Ocean Pelagic Zone Benthic zone Abyssal zone Open ocean of any depth. Benthic zone Any sea-bottom surface at any distance from shore. Abyssal zone Deep area with high pressure zones, low temps and low oxygen levels.

Ocean Productivity Primary 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 Productivity Availability of nutrients Amount of solar radiation/sunlight.

Productivity in the Oceans Productivity 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 Levels A trophic level is a nourishment level in a food chain. Tertiary Consumers: Top of the pyramid Carnivores or secondary consumers. Consume the herbivores. Herbivores or primary consumers. Consume the producers Producers/Autotrophs Lowest level

Food Chain vs. Food Web Food Chain: sequence of organisms through which energy is transferred, starting with the primary producer. Food Web: group of interrelated food chains