CH 15 Ocean Life and Ocean Water

Salinity – total amount of dissolved solids in waterExpressed in parts per thousandAverage salinity of is 35 ppt or 3.5 %2 main dissolved solids– Chlorine = 55 % from earth’s interior (volcanoes)– Sodium = 30.6 % from chemical weathering of rocks

carried by rivers

Processes Affecting Salinity

Oceans are well mixedPercentages of major components in sea water are constant, but salinity varies from 33 – 38 ppt– Precipitation decreases salinity– Runoff from land decreases– Icebergs melting decreases– Evaporation increases– Formation of sea ice increases

Ocean VariationsTemperature– Mostly a function of latitude– A function of depth, too– Thermocline – rapid change in temp as depth changes– Only found in low latitudes

Density– Higher salinity = higher density– Lower temps = higher density– Deeper = more dense– Pycnocline – rapid change in density as depth changes– Only found in low latitudes

Ocean Layering

Most parts of the open ocean have a 3 layered structure– Surface zone – warmest; photosynthesis; mixed

zone due to waves, currents, and tides; mostly constant temperatures

– Transition zone – thermocline: pycnocline; halocline– Deep zone – abyss; very cold, very high pressures,

and very dark

Ocean Life

Marine organisms are classified according to where they live and how they move

1. Plankton – drift with ocean currents– Phytoplankton/plant and zooplankton/animal

2. Nekton – all animals that can swim/move on their own– Fish, squid, turtles

3. Benthos – living on or in the ocean bottom– Worms, coral, starfish

Marine Life Zones

3 factors to divide oceans into marine life zonesA) Availability of sunlight

– Photic; euphotic; aphoticB) Distance from shore

– Intertidal, neritic, oceanicC) Water depth

– Pelagic, benthic, abyssal

Other Ocean Stuff to Learn

Hydrothermal ventsCoral reefsAbyssal creaturesSharks

Oceanic Productivity

Primary productivity – Production of organic stuff from inorganic stuff…– Photosynthesis - – Chemosynthesis – bacteria and H2S

Productivity in polar oceans – Seasonal variation– Salt concentrating nutrients– Limit of available sunlight

Productivity in tropical oceans– Sunlight penetrates far– Thermocline prevents mixing– Lack of nutrients limits production

Productivity in temperate oceans– Sunlight and nutrient supply limit productivity– Each season has its effect– Spring is when the big bloom occurrs.

Oceanic Feeding Relationships

Trophic levels– Feeding stages on a food pyramid– Herbivores and carnivores

Transfer efficiency– Energy transfer between trophic levels is very

inefficient…usually about 2 %...wowFood chains and food webs– Yada, yada, yada