CH 15 Ocean Life and Ocean Water Salinity
- Slides: 10
CH 15 Ocean Life and Ocean Water Salinity – total amount of dissolved solids in water Expressed in parts per thousand Average 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 mixed Percentages 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 Variations Temperature – 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
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
Marine Life Zones 3 factors to divide oceans into marine life zones A) Availability of sunlight – Photic; euphotic; aphotic B) Distance from shore – Intertidal, neritic, oceanic C) Water depth – Pelagic, benthic, abyssal
Other Ocean Stuff to Learn Hydrothermal vents Coral reefs Abyssal creatures Sharks
Oceanic Productivity Primary productivity – Production of organic stuff from inorganic stuff… – Photosynthesis – Chemosynthesis – bacteria and H 2 S 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 %. . . wow Food chains and food webs – Yada, yada
