UNDERSTANDING:
- Introduced alien species can escape into local ecosystems and become invasive
- Competitive exclusion and the absence of predators can lead to reduction in the numbers of endemic species when alien species become invasive
- Pollutants become concentrated in the tissues of organisms at higher trophic levels by biomagnification
- Macroplastic and microplastic debris has accumulated in marine environments
APPLICATIONS:
-Study of the introduction of cane toads in Australia and one other local example of the introduction of an alien species
- Discussion of the trade-off between control of the malarial parasite and DDT pollution
- Case study of the impact of marine plastic debris on Laysan albatrosses and one other named species
SKILLS
- Analysis of data illustrating the causes and consequences of biomagnification
- Evaluation of eradication programs and biological control as measures to reduce the impact of alien species
ALIEN AND INVASIVE SPECIES
Introduced alien species can escape into local ecosystems and become invasive
human activity often results in an organism being introduced to an area where it did not previously occur. Species that are native to an area are referred to as endemic whereas species that are not native but are introduced by humans are referred to as alien species
The impacts of an alien species are usually only significant if it increases in number and speeds rapidly. Species that do this are described as invasive.
Many of these invasive species have significant effects on the ecosystems where they are released. For example, rats introduced in New Zealand contributed to the extinction of ground nesting bird species by predating their eggs.
ALIEN SPECIES COMPETE WITH ENDEMIC SPECIES
Competitive exclusion and the absence of predators can lead to reduction in the numbers of endemic species when alien species become invasive
An alien species can become so reproductively successful and aggressive that is dominates the new ecosystem and poses a serious threat to biodiversity. Organisms that are endemic to an area may occupy similar niches as the alien species.
One consequence of the competition might be that either or both species may occupy smaller realized niches. If the alien species lacks predators it may be able to out-compete native species and become invasive.
Alternatively, the ability of a new ecosystem to resist and alien species can prevent it from becoming invasive.
BIOMAGNIFICATION
Pollutants become concentrated in the tissues of organisms at higher trophic levels by biomagnification
Sone toxins build up in the body of organisms, particularly if the toxic is fat-soluble and not easily excreted. This is known bioaccumulation.
Biomagnification is the process by which chemical substances become more concentrated at each trophic level. At each stage in a food chain, the predator will accumulate higher contraptions of the toxin than its prey. This is because they predator consumes large quantities of prey during its lifetime and bioaccumulates the toxic that they contain.
The concentration of toxic in the highest trophic levels may be lethal. even when the concentrations in organisms at the start of the food chain were very love.
Figure 11 shows the concentrations of PBCs in an aquatic food chain the Great Lakes. These chemicals were used as insulators in electrical devices and as flame-retardants.
- Introduced alien species can escape into local ecosystems and become invasive
- Competitive exclusion and the absence of predators can lead to reduction in the numbers of endemic species when alien species become invasive
- Pollutants become concentrated in the tissues of organisms at higher trophic levels by biomagnification
- Macroplastic and microplastic debris has accumulated in marine environments
APPLICATIONS:
-Study of the introduction of cane toads in Australia and one other local example of the introduction of an alien species
- Discussion of the trade-off between control of the malarial parasite and DDT pollution
- Case study of the impact of marine plastic debris on Laysan albatrosses and one other named species
SKILLS
- Analysis of data illustrating the causes and consequences of biomagnification
- Evaluation of eradication programs and biological control as measures to reduce the impact of alien species
ALIEN AND INVASIVE SPECIES
Introduced alien species can escape into local ecosystems and become invasive
human activity often results in an organism being introduced to an area where it did not previously occur. Species that are native to an area are referred to as endemic whereas species that are not native but are introduced by humans are referred to as alien species
The impacts of an alien species are usually only significant if it increases in number and speeds rapidly. Species that do this are described as invasive.
Many of these invasive species have significant effects on the ecosystems where they are released. For example, rats introduced in New Zealand contributed to the extinction of ground nesting bird species by predating their eggs.
ALIEN SPECIES COMPETE WITH ENDEMIC SPECIES
Competitive exclusion and the absence of predators can lead to reduction in the numbers of endemic species when alien species become invasive
An alien species can become so reproductively successful and aggressive that is dominates the new ecosystem and poses a serious threat to biodiversity. Organisms that are endemic to an area may occupy similar niches as the alien species.
One consequence of the competition might be that either or both species may occupy smaller realized niches. If the alien species lacks predators it may be able to out-compete native species and become invasive.
Alternatively, the ability of a new ecosystem to resist and alien species can prevent it from becoming invasive.
BIOMAGNIFICATION
Pollutants become concentrated in the tissues of organisms at higher trophic levels by biomagnification
Sone toxins build up in the body of organisms, particularly if the toxic is fat-soluble and not easily excreted. This is known bioaccumulation.
Biomagnification is the process by which chemical substances become more concentrated at each trophic level. At each stage in a food chain, the predator will accumulate higher contraptions of the toxin than its prey. This is because they predator consumes large quantities of prey during its lifetime and bioaccumulates the toxic that they contain.
The concentration of toxic in the highest trophic levels may be lethal. even when the concentrations in organisms at the start of the food chain were very love.
Figure 11 shows the concentrations of PBCs in an aquatic food chain the Great Lakes. These chemicals were used as insulators in electrical devices and as flame-retardants.
PLASTICS IN THE OCEAN
Macroplastic and microplastic debris has accumulated in marine environments
Plastic is a broad item that describes a number of different polymers that are used in a growing number of disposable consumer items. Some plastics enter the ocean through direct disposal from ships and platforms, but the majority comes from litter being blown into water systems
Macroplastic is large visible debris including nets, buoys, buckets and trash that has not degraded (Figure 15)
Macroplastic and microplastic debris has accumulated in marine environments
Plastic is a broad item that describes a number of different polymers that are used in a growing number of disposable consumer items. Some plastics enter the ocean through direct disposal from ships and platforms, but the majority comes from litter being blown into water systems
Macroplastic is large visible debris including nets, buoys, buckets and trash that has not degraded (Figure 15)
Physical and chemical degradation of macro plastic results in microplastic fragments that are harder to see but are more omnipresent
Ocean currents transport garbage to five concentration areas across the globe called gyres. These are very large "patches" within the ocean where circular currents concentrate the plastic waste.
Some of the consequences of marine plastic pollution are:
- The degradation of the plastic at sea releases persistent organic chemicals into the ocean that can bioaccumulate and biomagnify
- Plastics absorb other persistent organic chemicals and this concentrate these toxins
- Animals eat or become tangled in plastic pollution
Ocean currents transport garbage to five concentration areas across the globe called gyres. These are very large "patches" within the ocean where circular currents concentrate the plastic waste.
Some of the consequences of marine plastic pollution are:
- The degradation of the plastic at sea releases persistent organic chemicals into the ocean that can bioaccumulate and biomagnify
- Plastics absorb other persistent organic chemicals and this concentrate these toxins
- Animals eat or become tangled in plastic pollution