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Algae and Aquatic Plants for Fisheries

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Introduction Role of algae and aquatic plants as primary producers Aquaculture of algae and ... water supplies Control of problem algae and aquatic weeds ... – PowerPoint PPT presentation

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Title: Algae and Aquatic Plants for Fisheries


1
Algae and Aquatic Plants for Fisheries
  • Kevin Fitzsimmons, Ph.D.
  • Professor, University of Arizona
  • Visiting Fulbright Professor, Thailand
  • President, World Aquaculture Society
  • Kasetsart University
  • August 4, 2004

2
Introduction
  • Role of algae and aquatic plants as primary
    producers
  • Aquaculture of algae and aquatic plants
  • Invasive species problems
  • Control of problem algae and aquatic weeds

3
Role of algae and aquatic plants as primary
producers
  • In most aquatic systems algae (phytoplankton and
    attached algae) and aquatic plants are the
    primary source of oxygen and food.

4
Role of algae and aquatic plants as primary
producers
  • Algae and plants also remove/convert waste from
    animals and bacteria.

5
Nitrogen cycle in aquatic systems
6
Productivity of water can be a measure of
fisheries potential
  • Waters with high productivity are able to support
    high fish populations and growth

7
Productivity of water can be a measure of
fisheries potential
  • Tools to measure productivity
  • Secchi disk measure of water clarity
  • Light and dark bottle reactions - measures of
    photosynthesis and respiration
  • Fluorometer measures amount of chlorophyll
  • Direct algae/plant counts and identification

8
Secchi disk
Indirect measure that estimates algae population
from clarity. Inaccurate method.
9
Light-Dark Reactions in BOD bottles
1. Use one clear exposed bottle to determine
photosynthesis rate 2. Use one dark covered
bottle to determine respiration rate 3. Do
arithmetic to determine gross and net
photosynthesis
10
Fluorometer Systems
Old style
New styles
1. Water sample is placed inside 2. Sample is
excited by light radiation 3. Chlorophyll
molecules have excited electrons, which give
off fluorescence when they drop to level.
11
Direct counts and identification of algae
3. Count cells in randomly selected region
1. Sample on counting slide
2. Focus on counting grid on low magnification
4. Identify algae
12
Fisheries estimate based on productivity
  • Light dark bottle results
  • Plus one or more of the other methods can be used
    to estimate
  • About 10 energy or biomass conversion between
    trophic stages

13
Aquaculture of algae and aquatic plants
  • Phytoplankton algae used to feed larval fish,
    shrimp, mollusks
  • Macroalgae (kelps, red algae) widely used for
    human consumption
  • Many aquatic plants used for human and animal food

14
Invasive plants and algae
  • Invasive weeds damage environment, reduce crop
    yields, and poison livestock
  • Aquatic weeds clog irrigation systems, fill
    aquaculture ponds, increase mosquito habitat
  • Blue-green algae cause taste and odor problems in
    fish and drinking water supplies

15
Control of problem algae and aquatic weeds
  • Chemical controls (herbicides, copper, etc)
  • Mechanical controls (dredges, rakes, backhoes)
  • Environmental controls (nutrient reduction,
    shade)
  • Biological controls (fish, insects)
  • Integrated Pest Management

16
Algae - water quality project
17
Algae - water quality project
  • Collected data on water chemistry and physical
    parameters
  • Counted algae and determined recruitment and
    growth
  • Determined nutrient sources and timing
  • Changed water removal from dam
  • Saved utilities 600,000 per year on water
    treatment costs

18
Salvinia molesta in the Colorado River
  • Aquatic weed introduced from Brazil
  • Filling irrigation canals and damaging irrigation
    pumps
  • May impact fish and wildlife

19
Control of Salvinia molesta ???
  • Mechanical controls not working
  • Chemical controls not working and damaging the
    environment

20
Best hope for control of Salvinia
  • Integrated pest management plan
  • Limited spray, some mechanical, and introduce
    biological control
  • Cyrtobagous salvinia, Salvinia weevil from
    Brazil

21
Quick overview
  • Algae and aquatic plants critical to aquatic
    environments
  • Many useful aspects for humans
  • Can cause problems for humans when out of control
  • Many new jobs and opportunities managing aquatic
    systems
  • Thank you for opportunity to present our research
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