Understanding the Environmental Requirements for Fish Lesson 2
Understanding the Environmental Requirements for Fish Take a drink of water. How good does it taste? How important is water to your life? How important is water to fish?
Terms Aeration Ammonia toxicity Biomass Eutrophication Nitrogen cycle Oxygenation pH Phytoplankton Plankton Salinity Water biology Water chemistry Zooplankton
Objectives Describe the factors affecting water quality Understand water oxygenation Understand the effects of nitrogen Describe the effects of other common compounds in water
What factors affect water quality? Water is a simple compound consisting of 2 parts hydrogen and 1 part oxygen. Water and its quality are very important in fish production Water quality has 3 characteristics –chemical characteristics –physical characteristics –biological characteristics
Chemical characteristics Water chemistry - many dissolved molecules combined in the water. Common substances in water: –Dissolved oxygen –Nitrogen –Hydrogen sulfide –Carbon dioxide –Iron
Chemical characteristics pH and salinity affect water chemistry pH –Measure of the water’s acidity or alkalinity. Salinity –Amount of dissolved salt in the water.
Physical characteristics Temperature –Determines physical characteristics –Physical characteristics of water Solid Liquid Gas –Fish have a specific range of temperatures that they can survive
Water biology –All of the living and non-living organisms in the water –From the large aquatic plants to the small microscopic organisms Plankton –Tiny plants and animals that float in the water
Plankton Types of plankton Phytoplankton –Algae plankton which produce oxygen through photosynthesis Zooplankton –Microscopic animal life that is often used as food by many fish
Water biology Biomass –All living organisms in a given location
What is water oxygenation? Fish rely on dissolved oxygen in water to sustain their life functions. The amount of available oxygen is a limiting environmental factor. When oxygen is limited, oxygen can be added. This process is called oxygenation.
What is water oxygenation? One source of oxygen is from the air above the water. This process of obtaining oxygen from air above water is called aeration.
Methods of aeration Splashing –Water is added to system –Water splashed against concrete or something similar –Allows more water molecules to come into contact with air molecules Pumping air or oxygen into water –Allows oxygen molecules to come in contact with water molecules –Allows oxygen to become dissolved in the water –Commonly seen in fish tanks
Methods of aeration Spraying water in air –Use of a fountain or a paddle wheel. –Water is sprayed into air causing it to come into contact with oxygen. –Water catches this oxygen and brings back down into water.
Methods of aeration Using chemicals –Potassium permanganate added to ponds causing a chemical reaction that releases oxygen. –Common method of using chemicals is fertilizing the pond. This allows aquatic plants to grow increasing photosynthesis.
What are the effects of nitrogen in water? Nitrogen is an abundant element in the environment. Nitrogen circulates through the atmosphere, soil, water, animals, and plants. This circulation is known as the nitrogen cycle. Excessive nitrogen in water can be toxic to fish. Highly intensive fish production systems, nitrogen can be a problem.
Where does the nitrogen come from? Organic wastes in the water causes excessive nitrogen in fish production. Organic material can be manure from fish or uneaten feed. As this material decomposes, ammonia is released. Ammonia converted to nitrites. Ammonia and nitrites both harmful to fish.
Ammonia toxicity –Level of ammonia that can cause harm High levels of nitrite in the water will prohibit blood of the fish from effectively carrying oxygen.
Ammonia toxicity Factors making ammonia more toxic –Increasing temperatures –pH becomes more alkaline –Dissolved oxygen decreases –Carbon dioxide increases –Salinity decreases
Preventing nitrogen problems Intensive fish production cause nitrogen levels to change quickly. Test nitrogen levels regularly. Care should be taken to prevent over feeding of the fish. Design system to allow for proper water flow to remove waste from system.
What are the effects of other common compounds found in water? Phosphorus, chlorine, and heavy metals may cause problems with water quality. Phosphorus –Usually attributed to wastes entering water. –In combination with nitrogen can cause excessive nutrients in water. –This is called eutrophication. –This leads to algae blooms causing a decrease in oxygen in water.
What are the effects of other common compounds found in water? Chlorine –Usually attributed to municipal chlorinated water entering the system. –Can cause problems for some species of fish. –To eliminate chlorine Water needs to be de-chlorinated by aging or chemical treatments.
What are the effects of other common compounds found in water? Heavy metals –Lead and mercury. –Attributed to water pollution from manufacturing or illegal dumping. –May not kill the fish, however absorbed into fish and cause problems for humans consuming the fish. –Test water for heavy metals.
Review / Summary What factors affect water quality? What is water oxygenation? What are the effects of nitrogen in water? What are the effects of other common compounds found in water?