Warm Up 2/11/09 Which of the following is NOT a process that decreases the salinity of seawater? a. icebergs melting c. runoff from land b. precipitation d. evaporation In addition to salinity, what factor affects the density of seawater? a. salt content c. latitude b. temperature d. depth Ocean salinity is usually expressed in ____. a. charts c. parts per thousand b. chemical formulas d. parts per billion Answers: 1) d. 2) b. 3) c.

The Diversity of Ocean Life Chapter 15, Section 2

Classification of Marine Organisms Marine organisms can be classified according to where they live and how they move Plankton include all organisms—algae, animals, and bacteria—that drift with ocean currents Phytoplankton – the algae that undergo photosynthesis Zooplankton – animal plankton Nekton include all animals capable of moving independently of the ocean currents, by swimming or other means of propulsion The term benthos describes organisms living on or in the ocean bottom

Plankton Phytoplankton Zooplankton

Nekton

Benthos

Marine Life Zones The distribution of marine organisms is affected by the chemistry, physics, and geology of the ocean Three factors are used to divide the ocean into distinct marine life zones: the availability of sunlight, the distance from shore, and the water depth

Availability of Sun Photic Zone – the upper part of the ocean into which sunlight penetrates The clarity of seawater is affected by many factors, including the amount of plankton, suspended sediment, and decaying organic particles The euphotic zone is the portion of the photic zone near the surface where light is strong enough for photosynthesis (usually no deeper than 100 meters) Below the photic zone is the aphotic zone, where there is no sunlight

Photic Zone

Concept Check What is the difference between the photic zone and the aphotic zone? Sunlight penetrates the photic zone; no sunlight reaches the aphotic zone.

Distance from Shore Intertidal Zone – the area where the land and ocean meet and overlap The intertidal zone is a narrow strip of land which is alternately covered and uncovered between high and low tides Neritic Zone – covers the gently sloping continental slope The neritic zone is often shallow enough to put all of it in the photic zone, and is so rich with life that it supports 90% of the world’s commercial fisheries Oceanic Zone – area beyond the continental shelf Surface waters in the oceanic zone tend to not have many nutrients as they sink down to the deep ocean floor

Intertidal Zone

Water Depth Pelagic Zone – open ocean of any depth Animals in the pelagic zone swim or float freely Benthic Zone – includes any sea-bottom surface regardless of its distance from shore The benthic zone is mostly inhabited by benthos organisms Abyssal Zone – a subdivision of the benthic zone; includes the deep-ocean floor, such as abyssal plains The abyssal zone is characterized by high water pressure, consistently low temperature, no sunlight, and sparse life

Marine Life Zones

Marine Life Zones

Hydrothermal Vents Seawater seeps into the ocean floor through cracks in the crust The water is super-heated and saturated with minerals, and escapes back into the ocean The minerals precipitate out, giving the water the appearance of black smoke (black smokers) At some hydrothermal vents water temperature of 100ºC or higher support communities of organisms found nowhere else in the world

Hydrothermal Vents

Assignment Read Chapter 15, Section 2 (pg. 428-432) Do the Chapter 15 Assessment #1-32 (pg. 443-444) For Section 2: Do #’s 5-8, 16-19, 32