Bioaccumulation and Eutrophication

Hiya!

Recently discovered that I didn't now anything about bioaccumulation or eutrophication so I thought I would do a lovely blog to help it stick! Hopefully you'll accumulate this information as much as I'm hoping to! Happy reading!

Bioaccumulation is the process of chemicals being passed up a food chain in higher concentrations. It occurs when unnatural, insoluble molecules enter a the bottom of a food chain and as trophic levels go up, the concentrations of the accumulated substances increases. It is best explained using flow diagrams;

1. Small amounts of chemicals/toxins (often pesticides or chemicals from human activity which is poorly disposed of) are absorbed by plants
2. Primary consumers eat some of these plants an accumulate low concentration of the chemical/toxin
3. Secondary consumers eat the primary consumers, often multiple of them (E.g large fish eat multiple smaller fish) and they develop even higher concentrations of the chemical
4. The secondary consumers are eaten by higher level consumers. The high level consumers now contain the largest concentrations of the molecules which can confront an animals level of toxicity (fatal effects). 

(A picture of Geneva Lake that I took! Woah!)

We can use an example of factory pollutants and their effects on coastal areas;

1. Factories contaminate waters by releasing small quantities of pollutants and insoluble molecules into rivers and water sources
2. Marine plants absorb the chemicals 
3. Small fish eat some of the plants and accumulate higher concentrations in their bodies
4. Larger fish eat a few of the smaller fish and contain large amounts of the chemical
5. Seagulls feed on the larger fish but by eating them they can reach the maximum level of toxicity and subsequently die

(Shaun Low)

Although this is a very specific example, the ideas cam be applied to many scenarios based on the ecosystems and what stimuli change. As the frequency of plastic usage worldwide increases, we can see there is a significant increase in the bioaccumulation of microplastics. As the plastics molecules are insoluble and small, they are easily consumed by small fish and plankton which passes up the food chain. For exams you might not need to know this, but as a decent member of society you should make yourself aware. So what about eutrophication?

Eutrophication is where a body of water (lakes, rivers etc) becomes overly saturated with nutrients and plant rate growths rise rapidly as a consequence. Although this seems like a good thing, it can have detrimental effects on the marine ecosystems and destroy, desert the waters. 

1. Excessive nutrients (often from surface run-off) are flushed form the lands into the lakes and rivers
2. The nutrients cause small, algae and basic plants to rapidly grow.
3. As the algae grows, it thrives and photosynthesises rapidly which slowly begins to deplete the oxygen levels. Whilst growing rapidly and depleting oxygen levels, algae blocks out the sunlight for the other plants lower down in the water, stopping them from being able to photosynthesise properly. These plants die.
4. Decomposers in the water (bacteria and other microorganisms) break down the dead plant matter depleting oxygen concentrations further
5. The ecosystem begins to break down and die as there is little oxygen for fish, animals and plants to live in.