Trophic Dynamics Flashcards
What is meant by “bottom up” ecological controls
This refers to the availability of food and the bottom of the food chain determining the limits of production of upper trophic levels.
What is meant by “top down” ecological controls?
this refers to when top predators determine the regulation of the abundance of their prey and thereby determine the abundance of bottom trophic level.
Give a “top down” ecological control example
Keystone species → Sea otter → when the sea otter is not present urchins mass produce and eat kelp which results in low abundance or no kelp. When sea otters are present they keep urchin population down which results in more kelp growth.
Explain why a greater fraction of net primary productivity is consumed by herbivores in aquatic compared to terrestrial systems.
This is because a large portion of terrestrial primary consumption is biomass, compared to the smaller portion of the accumulation of aquatic biomass. Terrestrial biomass is concentrated in producers compared to consumers. On the contrary the biomass in aquatic systems is concentrated in consumers compared with producers.
What is Assimilation Efficiency?
Assimilation is when organisms convert external resources into their own biomass and energy stores.
What is production Efficiency?
Production Efficiency is measured by how much energy has passed from one trophic level to the next. It goes from producers to consumers and from consumers (ex:herbivores) to consumers (carnivores).
What is the difference between assimilation and production efficiency?
The difference between Assimilation and production efficiency is that assimilation is on an individual scale and production efficacy is on an ecosystem scale.
What is a trophic cascade?
A trophic cascade is made up of multiple trophic levels each having crucial roles in maintaining the balance and structure of ecosystems. The effects can take place in either direction in this cascade (up or down) the presence or absence of top predators can influence the abundance and behavior of their prey, which, in turn, affects the structure and dynamics of ecosystems.
Explain the concept of “fishing down marine food webs.”
this concept refers to the depletion of high-trophic level marine species due to overfishing. The species who are overfished have a decrease in population and as a result fishing activities change, they start fishing for lower trophic levels which can disrupt the balance within marine ecosystems, leading to a decline in biodiversity.
Explain the components and dynamics of an ocean food web, including the roles of primary producers, primary consumers, and top predators.
It consists of multiple trophic levels, including primary producers, primary consumers, and top predators.
- Primary Producers are typically photosynthetic organisms, such as phytoplankton and seaweed
- Primary consumers are herbivores that feed on primary producers. They include zooplankton, small fish, and invertebrates.
- Top predators are carnivorous species, such as sharks, large fish, ect. that prey on lower trophic level organisms.
Name three human activities that impact oceanic food webs.
overfishing → leads to depletion of many fish species, including top predators thus disturbing the balance of ocean food webs.
Pollution →agricultural runoff and industrial waste, can contaminate the ocean with chemicals and plastics.
Climate change → leads to rising sea temperatures and ocean acidification which affects the abundance of marine species which in turn affects the food web.
Explain the concept of a biomass spectrum in terrestrial ecosystems.
A biomass spectrum shows us the distribution of biomass across different trophic levels. Biomass accumulates in terrestrial systems much more than in ocean systems, this is because there are more producers than consumers in terrestrial systems and there are more consumers than producers in aquatic systems. Therefore, As we move up the trophic levels biomass decreases.
