Do Now Look at the images below Which
Do Now: Look at the images below. Which abiotic factors are the most critical limiting factors in these aquatic ecosystems? Why? Photic Zone Aphotic Zone
3. 3_ AQUATIC ECOSYSTEMS SC. 912. L. 17. 2 Explain the general distribution of life in aquatic ecosystems as a function of chemistry, geography, light, depth, salinity, and temperature. SC. 912. L. 17. 7 Characterize the biotic and abiotic components that define freshwater systems, marine systems and terrestrial systems.
Learning Objectives Discuss factors that affect aquatic ecosystems. Identify the major categories of freshwater ecosystems. Describe the importance of estuaries. Describe and compare the distinct ocean zones that make up marine ecosystems.
Nearly three-fourths of Earth’s surface is covered with water.
What abiotic factors affect organisms in aquatic ecosystem? Aquatic organisms are affected primarily by the water’s depth, and light as a result of it temperature, flow rate, salinity and concentrations of dissolved nutrients (nitrogen, phosphorus, ect).
Water Depth • Sunlight penetrates only a relatively short distance through water • The deeper the water, the less light can penetrate. Inversely Proportional relationship Light vs. Depth
Let’s Practice Scientific Method! 1. 2. 1. What is the independent variable? Light intensity Remember DRY MIX? 2. The dependent variable? Water depth (meters)
Photic Zone
Water Depth Photic zone Sunlit region near the surface in which photosynthesis can occur May be as deep as 200 meters in tropical seas Much less in rivers and lakes PHOTO refers to LIGHT
Plankton Phytoplankton: Photosynthetic algae live in the photic zone Producers (make their own food) Zooplankton: tiny freefloating animals-like organisms, or larvae that eat the phytoplankton. Consumers (eat or absorb nutrients from others)
Let’s see plankton in action! Video: The Secret Life of Plankton
Check Point What is phytoplankton? So, why do we find phytoplankton only in the photic zone? Remember all organisms that do photosynthesis have photosynthetic pigments = chlorophyll=green, so phytoplankton is green!
Misconception Alert A common misconception is that phytoplankton a too small to be important photosynthesizers. Reality: Oceans cover three quarters of Earth’s surface Each drop of water down to 100 meters is home to thousands of phytoplankton. Phytoplankton produce 70 % of Earth’s oxygen and are the main consumers of carbon dioxide, a greenhouse gas responsible for global warming.
Water depth creates zones: Photic Zone Aphotic zone Zone with light (photosynthesis) without light (Photosynthesis cannot occur) Benthic zone Rocks and sediments and on bottom of lakes and streams Benthos: zone. Aquatic organisms that live in the benthic
Temperature and Currents Warmer near the equator and colder near the poles Deepest parts of lakes and oceans are often colder than surface waters Currents can carry different temperature waters.
Nutrient Availability Nutrients such as phosphorus, nitrogen are not consistent in aquatic habitats. Many factors affect their distribution
Salinity • there are different levels of salinity across aquatic ecosystems Freshwater < 0. 05% Salt Brackish Water 0. 05% - 3 % Salt Saline Water 3% - 5 % Salt
Classification of species by salinity tolerance Stenohaline Species Adapted to a narrow range of salinity Ex. Largemouth bass lives only in freshwater but won’t survive in saline water. Euryhaline Species: Adapted to a wide range of salinity Found in both in fresh or marine environments They are good at regulating the amount of water in their bodies. Ex. Salmon (born in fresh water, then migrate to the ocean, and returns to freshwater to reproduce)
Salinity Salt is required for normal cell functioning Aquatic organisms are adapted to specific salinity levels If too much, water will leave cells If too little, cell will swell and may burst.
Freshwater ecosystems can be divided into three main categories: rivers and streams, lakes and ponds, and freshwater wetlands.
Rivers and Streams Often originate from underground water sources in mountains or hills Have plenty of dissolved oxygen but little plant life near source Sediments build up and plants establish themselves downstream Depend on terrestrial plants and animals that live along their banks for food.
Lakes and Ponds Based on a combination of plankton and attached algae and plants Water flows in and out of lakes and ponds and circulates between the surface and the benthos, distributing heat, oxygen, and nutrients.
Freshwater Wetlands • Wetland – • • Water either covers the soil or is present at or near the surface for at least part of the year May have flowing water Nutrient-rich, highly productive, and serve as breeding grounds for many organisms Purify and filter water Freshwater bogs, freshwater marshes, and freshwater swamps.
Estuary Saltwater wetland Where river meets the sea Affected by tides Spawning and nursery grounds for many ecologically and commercially important fish and shellfish species.
Marine Ecosystems Ocean divided into zones based on depth and distance from shore: Intertidal zone, the coastal ocean, and the open ocean.
Ocean
1. What is this diagram telling me? 2. Now sketch a graph that illustrate the concept shown. (no numbers needed, just a line showing relationship)
Intertidal Zone Submerged in seawater at high tide and exposed to air and sunlight at low tide Barnacles and seaweed attached to rocks. Organisms who live here adapted to extreme conditions
Coastal Ocean Extends from the low-tide mark to the outer edge of the continental shelf Water is brightly lit, and is often supplied with nutrients- very productive.
Open Ocean Begins at the edge of the continental shelf and extends outward More than 90 percent of the world’s ocean Depth ranges from 500 m along to more than 10, 000 m Divided into photic and aphotic zones.
Photic Zone Typically has low nutrient levels and supports only small phytoplankton Most photosynthesis occurs in the top 100 meters of the open ocean.
Aphotic Zone Permanently dark ( no photosynthesis can occur) Producers (autotrophs) use chemical energy to synthesize carbohydrates (sugars) in a process called chemosynthesis. Deepest parts of the ocean.
Let’s Practice Which of the following are abiotic factors that shape aquatic ecosystems? A. worms, plants and water temperature B. wind, precipitation, and soil type C. salinity, temperature, light, water depth D. sunlight, mushrooms, and water depth
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