Biological Oceanography: Factors Affecting Life and Ocean Zones

Factors Affecting Life: Light Dissolved Nutrients Temperature Salinity Dissolved Gases pH Pressure

Light Needed for photosynthesis. Must occur in the first few 100 m of ocean. Also trigger breeding some species.

Classification by Light:

Dissolved Nutrients Nutrients are substances that provide nourishment and growth. Required for production of organic (carbon based) matter. Problems: Phosphorous Loading – detergents Nutrient Loading in Halifax Harbour

Dissolved Nutrients

Temperature The mixed layer is near the surface where the temperature is roughly that of surface water. In the thermocline, the temperature decreases rapidly from the mixed layer temperature to the much colder deep water temperature. The mixed layer and the deep water layer are relatively uniform in temperature, while the thermocline represents the transition zone between the two.

Temperature Cold Blooded: Warm Blooded: Changes in temperature will directly affect metabolic rate. Warm Blooded: Have blubber that acts as insulation.

Salinity Salt content in ocean directly effects buoyancy of organism. Species have adapted physical features to combat this problem. Eg. Fish – Swim Bladder Interior salinity of most marine life is equal to ocean’s salinity.

Dissolved Gases CO2 and O2 are needed to stay alive in the ocean. O2 does not dissolve easily in ocean. 100 X more gaseous oxygen in air than ocean. CO2 dissolves more easily in ocean. 60 X more carbon dioxide in ocean than air.

pH Pressure Pure Water = 7 Seawater = 8 Increases drastically with depth. -Sea Level: 14.7 psi -Under 33 feet: 30 psi -Under one mile: 2 333 psi

Ocean Zones by Light

1. Photic Zone 2. Disphotic Zone 3. Aphotic Zone 0-200m sunlit layer at the ocean’s surface upper part of photic zone is where photosynthesis occur 2. Disphotic Zone 200 – 1000m where animals can see but not enough light for photosynthesis 3. Aphotic Zone 1000m and below largest region, no light

Ocean Zones by Surface Location Neritic zone spans from the low-tide line to the edge of the continental shelf in oceans near coast 2. Oceanic zone is the part of the open sea or ocean that is not near the coast

Ocean Zones by Depth Pelagic = Belonging to the upper layers of the open sea. Benthic = relating to the ocean bottom, living in or on the bottom of a body of water

Pelagic zone Is subdivided into 1. Photic zone receives enough sunlight to support photosynthesis. 2. Disphotic zone, where only small amounts of light penetrate 3.Aphotic zone into which no light penetrates.

Sub-divisions of the Bottom Benthic Zone 1)Littoral Zone – The shallow water area between high and low tides. 2) Sublittoral Zone - Ocean bottom near shore and out to edge of continental shelf 3) Bathyal Zone- seabed on the slopes 4) Hadal Zone or Abyssal Zone - deepest sea bed, trenches and floors

The Benthic Zone includes the seafloor and immediate substratum. Marine Zonation Neritic Zone Oceanic Zone Littoral Zone Benthic Zone Photic Zone Sublittoral Zone disphotic Zone The Benthic Zone includes the seafloor and immediate substratum. The Pelagic Zone is all the other open waters of the ocean. Bathyal Zone Benthic Zone Aphotic Zone Benthic Zone Hadal Zone or Abyssal Zone