1. AQUATIC PLANTS
ELODEA
TO EMILY:
the first 3 slides are the info i got with the websites
underneath. and my actual slides are the ones after that.

2. a)
• Among the most important for aquatic ecosystems are nitrogen and phosphorous.
Nitrogen and phosphorus are particularly critical to aquatic ecosystems because they often control the rates of photosynthesis. This is not because nitrogen and
phosphorous are the most abundant constituents of living things - carbon is significantly more abundant than either of them, and oxygen and sulfur are more abundant
that phosphorous. Instead, it is because nitrogen and phosphorous are less available to plants relative to their growth requirements than are other elements.
Phosphorus is often in short supply in an aquatic ecosystem and limits plant and algae growth. The primary natural sources of phosphorus to aquatic ecosystems are the
slow dissolution of minerals in soil and decomposition of allochthonous organic matter, such as leaf litter, although natural sources also include soil dusting and burning.
But human activities have dramatically increased delivery of phosphorus to fresh waters. Primary anthropogenic sources of the nutrient include sewage (whether treated
or not), septic tank leachate, fertilizer runoff, soil erosion, animal waste and industrial discharges.
A lack of nitrogen can limit plant growth in both terrestrial and aquatic ecosystems. As with phosphorous, we often add nitrogen to farm fields and gardens in the form of
fertilizers to increase production of crops and other desirable plants.
For example, nitrogen fixation readily occurs in freshwater. When nitrogen availability limits plant or algae growth in freshwater ecosystems, populations of nitrogen
fixing organisms (especially cyanobacteria) increase until some other nutrient - often phosphorus - becomes limiting. Because nitrogen fixation is less rapid in marine
environments, nitrogen is more likely to limit primary production in marine and estuarine environments than in freshwater. Nitrogen can be limiting in phosphorus-rich
environments.
akes and streams may also undergo anthropogenic eutrophication, where human inputs of nutrients create excessive algal blooms and result in decreased water clarity
and dissolved oxygen
In aquatic ecosystems, it is important to recognize that there are healthy ranges all of these aspects of water chemistry, including water temperature, dissolved oxygen,
pH and nutrients. If too little of one of these components is available, the ecosystem will suffer, just as it will if there is too much of another.
http://www.tu.org/conservation/eastern-conservation/brook-trout/education/nutrients-in-aquatic-systems
degradation of water and habitat quality. Nitrogen and phosphorus are essential components of structural proteins, enzymes, cell
membranes, nucleic acids, and molecules that capture and utilize light and chemical energy to support life.
Nutrient enrichment of marine waters promotes the growth of algae, either as attached multicellular forms (e.g. sea lettuce) or as
suspended microscopic phytoplankton, because algae can grow faster than larger vascular plants. Small increases in algal
abundance or biomass have subtle ecological responses that can increase production in food webs sustaining fish and shellfish,
even producing higher fish yields. However, over-stimulation of algal growth leads to a complex suite of interconnected
biological and chemical responses that can severely degrade water quality and threaten human health and sustainability of living
resources in the coastal zone.
http://www.eoearth.org/article/Eutrophication

3. hypoxia
• Hypoxia, or oxygen depletion, is a phenomenon that occurs in aquatic environments as dissolved oxygen (DO; molecular
oxygen dissolved in the water) becomes reduced in concentration to a point where it becomes detrimental to aquatic organisms
living in the system. Dissolved oxygen is typically expressed as a percentage of the oxygen that would dissolve in the water at the
prevailing temperature and salinity (both of which affect the solubility of oxygen in water; see oxygen saturation and underwater).
An aquatic system lacking dissolved oxygen (0% saturation) is termed anaerobic, reducing, or anoxic; a system with low
concentration—in the range between 1 and 30% saturation—is called hypoxic or dysoxic. Most fish cannot live below 30%
saturation. A "healthy" aquatic environment should seldom experience less than 80%. The ex-aerobic zone is found at the
boundary of anoxic and hypoxic zones.-------> wikipedia
• http://www1.eere.energy.gov/biomass/pdfs/biomass_growth.pdf

4. hypothesis of eutrophication
• Eutrophication brings about increased dissolved oxygen consumption in lakes progressively lowering
dissolved oxygen concentrations. Eutrophic lakes covered with ice and snow, wetlands and northern
rivers receiving large quantities of organic matter from their ice and snow, exhibit substantial DO
losses during the winter (Likens, 1972).
At higher temperatures, water can hold less oxygen when saturated which results in less oxygen directly
available and a lower percentage of the metabolic demand being satisfied, since the metabolic rate of organisms
increases with increasing temperature (Klaff, 2002).
Eutrophication can have both temporary and more irreversible effects on aquatic ecosystems. Significant
fluctuations in dissolved oxygen concentrations between day and night can occur in waters where there is
enhanced plant growth (Muir, 2001). This can cause problems in the early morning when low oxygen levels, the
result of plant respiration, may lead to the death of invertebrates and fish. This process can be compounded
when algal blooms, through their decay, further reduce the oxygen content of water. (Klaff, 2002). The growth
and/or decay of bottom-dwelling macro-algae can also lead to the deoxygenating of sediments. Certain algal
species, particularly freshwater blue-green algae, can produce toxins, which may seriously affect the health of
mammals, including humans, fish and birds (Muir, 2001). This occurs either through the food chain, through
contact with, or ingestion of, the algae. Algal species also cause fish deaths, for example by physically clogging
or damaging gills, and causing asphyxiation. Eutrophication ultimately detracts from biodiversity, through the
dominance of nutrient-tolerant plants and algal species. These tend to displace more sensitive species of higher
conservation value, changing the structure of ecological communities (Muir, 2001).
Eutrophication can also adversely affect a wide variety of water uses such as water supply (e.g. algae clogging
filters in treatment works), livestock watering, irrigation, fisheries, navigation, water sports, angling and nature
conservation (Hutchinson, 1970). It can give rise to undesirable aesthetic impacts in the form of increased
turbidity, discoloration, unpleasant odors, slimes and foam formation (Klaff, 2002).

5. After examining the consequences of eutrophication we can see there is both temporary, but
more irreversible effects on aquatic ecosystems. It may lead to the death of invertebrates and
fish from over-population of algal blooms, and through their decay reducing the oxygen
content of water. The deoxygenation of sediments can produce toxins, which may seriously
affect the health of mammals, including humans, fish and birds. This may occur either
through the food chain, through contact with, or ingestion of the algae or even physically
clogging or damaging gills, and causing asphyxiation. Eutrophication ultimately will continue
to reduce biodiversity, through the dominance of nutrient-tolerant plants and algal species
unless we see a change in agricultural activities. At the rate eutrophication is negatively
effecting aquatic ecosystems, this will soon begin to have an effect on humans as well. If the
biodiversity decreases even more dramatically than it already is we may find ourselves being
responsible for the extinction of many fish and as a result could lose many commercially
important species such as salmon or tuna that are purchased and consumed daily. This could
eliminate many fishing-dependent industries as well. Even recreational fishing could come to
an end as fresh water tourist lakes become depleted of aquatic plants.

6. GROWTH LIMITING FACTORS:
Like all ecosystems, aquatic environments thrive best at optimal or “preferable” ranges of certain factors.
Specifically aquatic ecosystems are dependent on aspects of water chemistry including water temperature,
dissolved oxygen, pH, nutrients, and also sufficient sunlight for plants conducting photosynthesis. If
organisms cannot properly adapt to environmental changes, it can substantially damage the growth of all
surroundings.
Human inputs have been one of the leading causes of altered habitat quality in aquatic ecosystems.
Agricultural activities have increased delivery of nitrogen and phosphorus to fresh waters via sewage,
fertilizer runoff, soil erosion, animal waste and industrial discharges, Though nitrogen and phosphorus
are essential components of structural proteins, enzymes, cell membranes, nucleic acids, etc. and help
utilize light/chemical energy they also have many harmful effects. At unnaturally high rates, nitrogen and
phosphorous promote the rapid growth of algae. However the over-stimulation of algal growth leads to
biological and chemical responses that can severely decrease water quality & water clarity. Algae drape
over the water surface preventing light to be delivered to the plants below for photosynthesis inhibiting
their ability to metabolize prevent ing growth or repair. Furthermore, increased production of algae also
results in increased dead matter of algae that fuels bacterial growth in bottom waters and sediments
causing over-consumption of oxygen by bacterial metabolisms.
<---http://05lovesgeography.blogspot.ca/
2011/02/eutrophication.html

7. WHAT ABOUT BIOMASS? WHAT IS HYPOXIA?
In an aquatic system, increases in
biomass of organisms such as algae
during eutrophication result in increased
production in food webs sustaining fish
and shellfish, even producing higher fish
yields. However, it is common when algal
biomass builds during blooms that
resulting algal dead matter sinks to
bottom waters and sediments igniting
bacterial population sizes. With increased
bacteria consuming excessive rates of
algae there is a high metabolic
http://en.wikipedia.org/wiki/Eutrophication
consumption of oxygen caused by the
bacteria. If the rates of oxygen dissolving
in water are slower than bacterial
metabolism consuming it, then bottom
waters become hypoxic. This
phenomenon occurs when oxygen in
reduced in concentration to a point where
it becomes detrimental to aquatic
organisms living in the system. Aquatic
systems lacking dissolved oxygen become
anaerobic creating conditions stressful or
even lethal for marine invertebrates and
fish. Eventually, this can become the birth
place of “Dead Zones” where no living
organisms can survive or reproduce.
http://www.saawinternational.org/eutrophication.jpg

8. HYPOTHESIS OF EUTROPHICATION
It may be assumed that with the addition of nutrients such as phosphorous and nitrogen by
eutrophication there would be a positive affect on aquatic plants, it is evident that the
resulting increased biomass of aquatic plant life results in more negative effects than positive
ones. Aquatic plants need proper conditions to survive, however algal blooms diminish their
ability to properly metabolize using photosynthesis and without photosynthesis all aquatic
life can only begin to deplete.