Aquatic Ecology Ocean Life Zones

Objectives for Aquatic Ecology Answer the following questions: What are the types of ocean life zones? What factors influence the kinds of life found there? What are the types of saltwater and freshwater life zones? How is the aquatic environment being affected by humans? How can we help sustain the water world?

Must Know for Project Know names and descriptions of zones Significant adaptations Trophic relationships Human factors

Aquatic Life Zones (Biomes) 1. The Saltwater/Marine Life Zone includes the oceans of the world. 75% of world’s surface is water. 2. The Freshwater life zone includes the rivers, ponds, streams, lakes and wetlands.

Aquatic Life Zones in Ocean

Common Organisms in Aquatic Life Zones Plankton are organisms that float or only weakly swim. Nektons are swimming life forms. Benthos organisms are the bottom dwellers. Decomposers are the bacteria.

Plankton

Nekton

Benthos Things that crawl/swim at bottom of ocean

Unique Factors for Water Life Sunlight only penetrates the first 100 feet. Pressure increases greatly with depth Temperature drops quickly through thermoclines. Salinity of the water dehydrates cells. Buoyancy provides physical support. Nutrients and pollution are in the water so they are dissolved and diluted. Chemicals for life (O2) have to be taken out of solution.

Oceans 75% of Earth’s surface. Key role in environment. Hydrologic cycle starting point. Controlling factor in weather. Important chemical sink and cycle controller. Absorbs heat from sun and redistributes it, regulating temperature. 250,000 known species of life. Two life zones: Coastal and Open Sea.

Intertidal Zone The area of shoreline between low and high tides is the intertidal zone. The organisms must be adaptable to the ocean or shore life because of changing conditions of salinity. They must also be able to hold on to rocks or sand when the waves crash on them.

Intertidal Zone Life

Coastal Zone, aka Neritic Zone Shore to end of continental shelf. 10% of ocean area: 90% of the life in the ocean. Site of large commercial fisheries. Site of most aquatic biodiversity: Reefs

Reef Systems Coral reef systems are a collection of many species co-habitating in a mutualistic and sometimes synergistic relationship. These are the rain forests of the ocean. The most biologically diverse habitat in the ocean.

Reef Systems in the Ocean

Effects of Mankind on Coasts 3.9 billion people (2/3 of world population) live along coasts or within 100 miles of a coast. Since 1900, the world has lost approximately half of the coastal wetlands by development. 55% of the USA’s wetlands and estuaries have been lost by development. This includes dredging and filling and waste contamination. Virginia’s coast has been eroding for over a century.

Effects of Mankind on Reefs Mankind has killed 10% of the world’s reef systems. 30% are in critical condition. 30% are in threatened condition. Only 30% are stable. At current rates 60% of the world’s reefs could be dead in 20-40 years.

Open Ocean Biological Zones Open Ocean/Open Sea zone has 3 vertical zones based on the penetration of sunlight. It contains about 10% of the marine species.

Open Ocean/Open Sea Zones Euphotic - upper zone, first 200 meters Bathyal, or Benthic - middle zone, 200-1500 meters Abyssal - bottom zone, below 1500 m

Euphotic Zone Photosynthesis (first 200 m) High Dissolved Oxygen (content varies widely from 1.5 ppm to 7.5 ppm), low nutrient levels, 90% of the ocean’s surface. Only 10% of commercial fish for the world. Zone of CO2 absorption from the atmosphere. Oceans help clean the greenhouse gases out of the atmosphere. It turns the CO2 into carbonate ions that are stored in sediment of the ocean bottom.

Bathyal (Benthic) Zone No photosynthesis Lower Dissolved Oxygen Colder Pressure higher

Abyssal Zone Totally dark, strange life forms Lowest level of Dissolved Oxygen Coldest; Temp can be below freezing, but pressure keeps it liquid. Highest nutrient layer due to the sediments

Marine Life Zones

Food Webs & Food Chains