Eutrophication sets off a chain reaction in the ecosystem, starting with an overabundance of algae and plants. The excess algae and plant matter eventually decompose, producing large amounts of carbon dioxide.
This lowers the pH of seawater, a process known as ocean acidification. Acidification slows the growth of fish and shellfish and can prevent shell formation in bivalve mollusks. This leads to a reduced catch for commercial and recreational fisheries, meaning smaller harvests and more expensive seafood. The state plans to establish five new sanctuary sites in Suffolk and Nassau Counties to transplant seeded clams and oysters, and to expand public shellfish hatcheries in the two counties through a dedicated grant program.
Eutrophication has had significant economic impacts on Long Island Sound, where commercial shellfisheries have lost millions of dollars annually since Recent projections indicate that without intervention, the Sound could lose all of its seagrass beds by , and that two-thirds of the Sound could lack enough oxygen for fish to survive. The NOAA scientists used aquaculture modeling tools to demonstrate that shellfish aquaculture compares favorably to existing nutrient management strategies in terms of efficiency of nutrient removal and implementation cost.
Documenting the water quality benefits provided by shellfish aquaculture has increased both communities' and regulators' acceptance of shellfish farming, not only in Connecticut but across the nation. Over-saturated terrestrial ecosystems contribute both inorganic and organic nitrogen to freshwater, coastal, and marine eutrophication, where nitrogen is also typically a limiting nutrient Hornung, et al. However, in marine environments, phosphorus may be limiting because it is leached from the soil at a much slower rate than nitrates, which are highly soluble Smith et al.
Numerous ecological effects can arise as primary production is stimulated, but there are three particularly troubling ecological impacts: decreased biodiversity, changes in species composition and dominance, and toxicity effects. When a body of water experiences an increase in nutrients, primary producers reap the benefits first. This means that species such as algae experience a massive population boom called an algal bloom.
Algal blooms tend to disturb the ecosystem by limiting sunlight to bottom dwelling organisms and by reducing the amount of dissolved oxygen available in the environment. Oxygen is required by all respiring plants and animals in an aquatic environment and it is replenished in daylight by photosynthesizing plants and algae. Under eutrophic conditions, dissolved oxygen is reduced by the dense population, and additional oxygen is taken up by microorganisms feeding on dead algae.
When dissolved oxygen levels decline, especially at night when there is no photosynthesis, hypoxia occurs and fish or other marine animals may suffocate. As a result, creatures such as fish, shrimp, and especially immobile bottom dwellers die off Horrigan et al.
In extreme cases, anaerobic conditions ensue, promoting growth of bacteria such as Clostridium botulinum that produces toxins deadly to birds and mammals. Zones where this occurs are known as dead zones. Eutrophication has been shown to cause competitive release by making abundant an otherwise limiting nutrient.
This causes shifts in the composition of ecosystems. For instance, an increase in nitrogen might allow new, more competitive species to invade and out compete original species. This has been shown Bertness et al. Some algal blooms, otherwise called "nuisance algae" or "harmful algal blooms," are toxic to plants and animals.
As stated above, this toxicity can lead to decreased biodiversity, or it can manifest itself in primary producers, making its way up the food chain. As a result of these toxic algae, marine animal mortality has been observed Anderson Freshwater algal blooms also pose a threat to livestock.
When these blooms die or are eaten, neuro - and hepatotoxins are released which can kill animals and may pose a threat to humans Lawton and Codd , Martin and Cooke Ultimately, these toxins can work their way up to humans, as is the case in shellfish poisoning Shumway Biotoxins created during algal blooms can become manifested in shellfish, leading to a variety of poisoning in humans.
Such examples include paralytic , neurotoxic, and diarrhoetic shellfish poisoning. Theoretically, other marine animals could also be vectors for such toxins. There are also toxic effects caused directly by nitrogen. When this nutrient is leached into groundwater, drinking water can be affected because concentrations of nitrogen are not filtered out. Nitrate NO 3 has been shown to be toxic to human babies. This is because bacteria can live in their digestive tract that convert nitrate to nitrite NO 2.
Nitrite reacts with hemoglobin to form methemoglobin, a form that does not carry oxygen. The baby essentially suffocates when its body receives no oxygen. In order to gauge how to best prevent eutrophication from occurring, specific sources that contribute to nutrient loading must be identified. There are two common sources of nutrients and organic matter: point and nonpoint sources. Point sources are directly attributable to one influence. In point sources the nutrient waste travels directly from source to water.
For example, factories that have waste discharge pipes directly leading into a water body would be classified as a point source. Then, to ensure a fair test , kids should measure the same amount of water into each jar. First, establish a control jar. Second, add maybe five, ten, and fifteen drops of fertilizer into three additional jars. As you peruse them, complete this worksheet.
After her students opened their Chromebooks, they set to work. In no time, they were learning about eutrophication. Feel free to pin images from this post. After her students filed in the next day, Ms. Sneed began. A buzz of excitement filled the air. Sneed continued with a container of plant fertilizer and an eyedropper for person 3.
Then she asked person 4 to get a graduated cylinder. Without missing a beat, her students got busy. Soon, everyone had prepared their jars. Next, Ms. Sneed asked students to collect more materials: a microscope, a slide, and a slipcover. She distributed a page with some circles. Draw what you see.
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