Unit 7: Ecology and conservation Flashcards
Population
A group of individual organisms of the same species living in a given area.
assumptions of capture-mark-release
no migration in or out, no deaths or births, marked at first have same chance of being captured on second occasion as unmarked, marks remain visible, marks don’t increase chance of predation.
Lindex index
(M (initially caught and marked) x N (total recaptired))/R (recaptured with marks)
Carrying capacity
Maximum size of poplation that an environment can support.
Density-dependent factors
Increasing effect as population increases. Basis for negative feedback )ex. competition, predation, infectious disease)
Density-Independent
Same effect however large the size of a population. (ex. sewater flooding, forest fires)
Community
Groups of populations living together in an area and interacting with each other.
Example of intraspecific competition
Plants compete for light, flowering plants for pollinating insects, Guillemots for breeding sites.
Example of intraspecific cooperation
Birds hudding together to conserve body heat, hunting in groups by chimpanzees, fish moving in “bait balls” to make it harder to be caught be predators
Herbivory
Primary consumers feeding on producers. The producer may or may not be killed. (ex. bison grazing on grasses).
Predation
One consumer species killing and eating another (ex. anteaters feeding on ants)
Interspecific competition
Two or more species using same resource, with the amount taken by one reducing the available amount to other. (ex. ivy climbing up oak trees and competing for light).
Mutualism
Two species living in a close assocation with both benefiting. (photosynthesizing zooxanthellae living in the cells of hard corals exchanging materials)
Parasitism
One species living inside, or on the outer surface of, another species and obtaining food from them. The host is harmed and parasite benefits. (ex. ticks living on skin of deer and feeding by sucking blood)
Pathogenicity
One species living inside another and causing a disease (ex.tuberculosis bacteriom infecting badgers).
Root nodules in Fabaceae
Plants (Fabaceae family) developing mutualism relationship with nitrogen fixing bacteria for a supply of ammonium. THe plant grows root nodules for bacteria to live in for protection and maintains low Oxygen conditions inside the nodules for them and supply them with sugar from photosynthesis, the bacteria absorbs nitrogen and fices it to produce ammonim and supplies it to the plant to prevent nitrogen deficiency.
Mycorrhizae in Orchidaceae
Orchids dependent on this relationship bc their seeds dont contain food reserves. Orchid supplies carbon compounds made by photosynthesis, while the fungus absorbs nitrogen and phosphorus fromm the soil and supplies it to the orchid and supplies carbon in organic comparounds obtained from the soil throw saprotophic methods and supplies water from soil also.
Zooxanthellae in hard corals
Hard corals secrete CaCO3 to form skeleton in whivh animals can live. Coral reefs are build from this. They often contain this algae absorbed from seawater and kept isnide the coral cells. The coral porivdes a safe environment (skeleton), grows close to the surface for algae to have a source of light, suuplies CO2 produced by cell respiration. Zooxanthellae supplies carbon compounds such as glucose produced through photosynthesis and supplies oxygen also.
Endemic species
Those that occur naturally in an area. Density-dependent regulat size.
Alien species + example
Those introduced by humans, deliberately or accidentally. Often size not regulated (because the factors of native habitat are absent). If increases in nr and spreads -> invasive species. Ex: red lionfish endemic to coastal seas in Indo-Pacific but moved due to escape from an aqaurion during a hurricane in Florida, and have multiplied on corals reefs around the area (hjelped by lack of predators adopted to avoid venomous spines) and compete for prey with endemic species by establishing teritories.
Top-down control
Acts from a higher trophic level to lower once (ex. increase in predator nr will decrease nr of prey in lower trophic level).
Bottom-up control
Acts from lower trophic level to higher (ex. population of producers may be limited by avaia´lability of mineral nutrients in soil or water)
Allelopathy
A biological phenomenon where one plant releases chemicals that influence the growth, survival, or reproduction of other plants.
Antibiotic secretion + example
Secreted by microorganisms to kill or prevent growth of others. Ex. peniccilium (a genus of fungi) that inhabit natural environments such as soil, saprotrophic, with hyphae to secrete enzymes into environments to digest carbon compounds. To reduce competition, Peniccilium species secrete penicillin (antibiotic) which interferes and causes the bacteria to die.
Allelopathic agents + example
Secreted into soil by plants kill or deter growth of neighboring plants. Ex. tree of heaven (native to China) has become invasive specie sin North America and releases an allelopathic chemical (ailanthone) which can also be extreacted from its root/stem bark.
Stability of an ecosystem + example
Means that it can persist indefinitely becaue of mechanisms operating within it. These mechansism are fragile and easily disrupted, so not always stable. Ex. Borneo Lowland Rainforest has existed for about 140 million years.
Requirements for stability
Steady supple of energy, nutrient cyclcing with closed system, individual species (esp keystone) must have high genetic diversity for survival under selection pressures.
Ex of environmental changes acting as disruptions
Harvesting and removable of materials disruptiing nutrient cycle, erosion causing loss of nutrients, eutrophication, climate variables must be within tolerance range
Eutrophication
occurs when the environment becomes enriched with nutrients, increasing the amount of plant and algae growth to estuaries and coastal waters
Tipping point
Systems crossing ecological thresholds difficult to reverse due to disturbance. Ex. deforestation of Amazon rainforest: need a large area of rainforest for the generation of atmospheric water vapour by transpiration, with consequent cooling, air flows and rainfall. But uncertainty over the minimum area of rainforest that is sufficient to maintain these processes.
A keystone species
one whose community activity has a diproportionate effect on the structure of an ecological community. Species diversity decreases if keystone species is lost..
Sustainable harvesting of palnts
bBrazil nutns are harvester from trees in the Amazon rainforest which can grow up to 50m and live for a 1000 years, Logging is threatening these strees. Sustainable harvesting dpends on leaving some nuts to germinate and grow into trees. In areas of intense harvesting, there are new or no young trees so harvesting is unsystainable.
Sustainable harvesting of fish
Cod inhabit cold watrers of the north Atlantic. Overfishing led to a collapse of cod population on some areas, and still not recovered, demonstrating importance of sustainable harvesting. As long as fishe are not harvester faster than the max rate of popualtion growth, stocks should not decline.
Sustainability of agriculture
Several factors negatively impact the sustainability of agriculture, reducing long-term productivity and harming ecosystems. Soil erosion depletes fertile topsoil, reducing crop yields and increasing desertification. Leaching of nutrients occurs when excessive irrigation or rainfall washes essential minerals (e.g., nitrogen and phosphorus) out of the soil, leading to nutrient depletion and water contamination. The supply of fertilizers and other inputs is often unsustainable, as synthetic fertilizers rely on non-renewable resources and can degrade soil health over time. Pollution from agrochemicals, including pesticides and herbicides, harms biodiversity, contaminates water sources, and disrupts ecosystems. Additionally, the carbon footprint of agriculture is significant due to emissions from machinery, transportation, and livestock production, contributing to climate change. Sustainable practices, such as crop rotation, organic farming, and precision agriculture, can help mitigate these impacts.
Consequences of eutrophication
Eutrophication is caused by the excessive leaching of nitrogen and phosphate fertilizers into aquatic ecosystems, often due to overuse in agriculture and runoff from fields. These nutrients promote algal blooms, which block sunlight and reduce oxygen levels in the water. When the algae die, decomposers break them down through respiration, increasing biochemical oxygen demand (BOD) and depleting dissolved oxygen. This leads to hypoxia (low oxygen conditions), causing fish and other aquatic organisms to suffocate, disrupting food chains and reducing biodiversity. Additionally, eutrophication can produce toxic algal blooms, which contaminate drinking water and harm both wildlife and humans. Sustainable farming practices, such as buffer zones and controlled fertilizer application, can help prevent eutrophication.
Biomagnification
Biomagnification is the process by which toxic substances accumulate and increase in concentration as they move up the food chain. It begins with pollutants, such as heavy metals or pesticides, entering the environment through industrial waste, agricultural runoff, or atmospheric deposition. These toxins are absorbed by primary producers (e.g., algae or plants) or consumed by primary consumers (e.g., zooplankton, small fish). Since these substances are fat-soluble and non-biodegradable, they remain stored in the tissues of organisms rather than being excreted. As higher trophic levels consume multiple prey organisms, the concentration of toxins increases, reaching dangerous levels in top predators.
Cause and effect of mercury biomagnification
Mercury pollution in ecosystems primarily originates from coal combustion, industrial discharge, and mining activities, releasing mercury into the air and water. In aquatic environments, bacteria convert mercury into methylmercury, a highly toxic form that accumulates in fish and other marine organisms. As mercury moves up the food chain, it becomes increasingly concentrated in large predatory fish such as tuna and sharks. When humans consume these fish, they are exposed to high levels of mercury, which can cause neurological disorders, developmental issues in children, and kidney damage. Mercury biomagnification also disrupts aquatic food webs, affecting fish populations and ecosystem stability.
Cause and effect of DDT biomagnification
DDT (dichlorodiphenyltrichloroethane) is a synthetic pesticide once widely used in agriculture and mosquito control. Though effective in killing pests, DDT persists in the environment and accumulates in fat tissues of organisms. As it biomagnifies up the food chain, top predators like birds of prey (e.g., eagles and falcons) suffer the most severe effects. High DDT levels interfere with calcium metabolism, causing birds to lay eggs with thin, fragile shells, leading to population declines. This was notably observed in the bald eagle and peregrine falcon, whose populations were drastically reduced before DDT was banned in many countries. Though restrictions have helped, DDT residues remain in some ecosystems, highlighting the long-term impact of biomagnification.
Biodegradable
A biodegradable substance is one that can be broken down into simpler, non-toxic compounds by natural decomposers such as bacteria, fungi, and other microorganisms. This process occurs over time, often returning nutrients to the environment and reducing waste accumulation. Plastics are not biodegradable.
Microplastics
plastic particles smaller than 5 millimeters in diameter, which originate from the breakdown of larger plastics or are manufactured as microbeads in products like cosmetics and toothpaste. They are often invisible to the naked eye and can be found in water, soil, and even the air.
Macroplastics
larger plastic debris, such as plastic bags, bottles, and fishing nets. These can eventually degrade into microplastics but remain as visible pollution in marine and terrestrial environments for long periods.
Causes and Effects of Microplastic Pollution in an Ocean Ecosystem
Microplastic pollution in the ocean is primarily caused by plastic waste mismanagement, industrial runoff, and the degradation of larger plastic debris due to environmental exposure. Washing synthetic fabrics, using cosmetic products containing microbeads, and improper disposal of plastic items all contribute to microplastic contamination. Once in the ocean, microplastics are ingested by marine organisms, including plankton, fish, and seabirds, leading to internal blockages, reduced feeding efficiency, and toxic chemical accumulation. These pollutants can also bioaccumulate and biomagnify in the food chain, affecting larger marine predators and ultimately humans who consume seafood. Additionally, microplastics can absorb harmful chemicals from the water, increasing the toxicity of marine environments.
Effects of Plastic Pollution on Marine Life
Plastic pollution has devastating effects on marine ecosystems due to its non-biodegradable nature. Large plastic debris, such as discarded fishing nets, entangles marine animals like sea turtles, seals, and dolphins, often leading to injury, drowning, or restricted movement. Seabirds and fish frequently mistake plastic for food, leading to starvation and internal injuries as plastic fills their stomachs without providing nutrition. Coral reefs are also affected, as plastic debris blocks sunlight and damages coral structures, reducing biodiversity. The long-term presence of plastics in the ocean disrupts food chains, reduces species populations, and contributes to the decline of marine health, making plastic pollution a major global environmental concern.
Rewilding
the process of restoring ecosystems by reintroducing native species, especially apex predators and keystone species, to restore natural ecological processes and improve biodiversity.
Methods of Ecosystem Restoration by Rewilding
Rewilding methods include the reintroduction of apex predators and keystone species to restore natural predator-prey relationships, the re-establishment of habitat connectivity over large areas to facilitate species migration, and the minimization of human impact through active ecological management, such as controlling invasive species and reducing human activity in sensitive areas.
Rewilding of the Hinewai Reserve in New Zealand
The Hinewai Reserve in New Zealand is a prime example of rewilding, where native forest restoration efforts are underway. In this reserve, invasive species are being controlled, and natural regeneration of native flora is encouraged. The reserve aims to reintroduce key species to restore ecological balance, and it focuses on minimizing human interference through careful management. The rewilding effort helps regenerate native habitats, increasing biodiversity and ecosystem health.
