Cycles and Mass Extinction

Flashcards covering cycles, mass extinction events, and climate change.

Biogeochemical Cycle

The movement and transformation of biomass such as carbon, nitrogen, phosphorous, sulphur and micro elements from non-living to living compartments and back, large proportions usually driven by microbes e.g. nitrogen cycle.

Carbon Sequestration

The process of removing carbon from the atmosphere through photosynthesis and calcification (generation of seashells). Calcification has a net store of carbon but releases co2

Calcification

A process where marine organisms create seashells and similar forms, sequestering carbon but also releasing carbon dioxide.

Anthropogenic CO2 Emissions

Carbon dioxide emissions resulting from human activities, primarily from fossil fuel burning (80%) and changes in land use like deforestation (20%). 45% of this remains in the atmosphere while 30% is taken up by oceans. the remainder is taken up by vegetation and soil.

Ocean Acidification

The reduction in the pH of the ocean due to the absorption of excess CO2 from the atmosphere, potentially affecting marine organisms and calcification rates. an 0.3 decrease in the atmosphere from 8.2 to 7.9 is predicted in the next 50 years. This process poses risks to biodiversity however the increased carbon available to marine organisms could also increase photosynthetic and calcification rates.

Extinction

The process by which species die out, normally occurring at a low rate, but can be greatly elevated during mass extinction events.

Causes of Mass Extinctions

Include bolide impact, vulcanism, increased oxygenation, and sea level changes, all linked to major changes in climate over geologically short periods.

Keystone Species

Species that play a critical role in maintaining the structure and function of an ecosystem; their loss can lead to the extinction of many other species.

6th Mass Extinction

The current period of species loss due to human activities (deforestation, habitat fragmentation, desertification, pollution) and climate change, with extinction rates far exceeding background levels.

Pressures on Ecosystems

Include climate change, deforestation, habitat fragmentation, desertification, and pollution (air, water, sound, and light).

Ecosystem Collapse

The breakdown of an ecosystem due to biodiversity loss, often indicated by the loss of plant species that serve as habitats for other species.

Human-Driven Extinction

Extinction caused by human activities, such as overexploitation of species ,and habitat destruction. The rapidity of the changes doesnt allow time to adapt leading to rapid depopulation.

Temperature-Dependent Ecological Processes

Many ecological processes, such as beetle egg development and metabolic rates, are influenced by temperature, with limits to how much they can increase.

Desertification

The process by which fertile land turns into desert, threatening ecosystems and human societies, often due to overabstraction of water and drought.

Coral Bleaching

The death of endosymbiotic algae (zooxanthellae) in coral reefs due to rising temperatures, leaving behind a “bleached” desert.

Climate Change Solutions

Include improved public awareness, political pressure, agreements like the Paris agreement, increased green energy use, and recycling.

release of matter from earths interior

volcanic eruptions. Matter released then disperses into the atmosphere and can interact with biota and oceans causing rapid changes. OR, exchanges of minerals between rocks, soil and the ocean, a slower process

When was the earliest evidence of life?

3.6 gy ago found in stromatolites and microfossils.

when did oxygen appear as a gas

about 2.7-2.5 billion years ago, during the Great Oxidation Event, when photosynthetic organisms began releasing oxygen into the atmosphere. this is evidenced by oxidised fe3+ which precipitated to form banded iron formations.

How oxygen caused a mass extinction

2.7 - 2.5 Gy ago photosynthetic organisms began releasing oxygen into the atmosphere. The build up of oxygen due to a lack of respiring organisms resulted in toxicity for anaerobic life forms, leading to significant biodiversity loss.

Sequester

to capture and store carbon or other substances in a form that is not easily broken down again

Calcification

a process by which organisms, particularly marine organisms, secrete calcium carbonate to form shells and skeletons, which can contribute to carbon sequestration.

Coccolithophore

a type of marine algae that plays a significant role in calcification and carbon cycling, by producing calcium carbonate plates called coccoliths.

soil as a terrestrial sink for co2

Soil acts as a crucial terrestrial carbon sink by storing carbon in organic matter and minerals, thus helping to mitigate atmospheric carbon dioxide levels. however soil has lost between 40 and 60 pg due to human activity such as burning fossil fuels and land-use changes.

Acidity and calcification

extant species evolved in a ph of 8.2 and increased acidity reduces the ability of organisms like corals and shellfish to survive, and if these organisms do not adapt they will not sequester co2 by producing calcium carbonate.

How the loss of species can lead to ecosystem collapse

loss of primary producers can lead to further extinctions. This disruption can diminish ecosystem functions such as nutrient cycling and habitat provision, ultimately resulting in a collapse of the entire ecosystem. Loss of keystone species can also cause this

North american bison

The North American bison Once roamed the Great Plains in massive herds however tens of thousands were shot in a few years nearly driving them to extinction.

Vulnerability and trophic levels

species at the top of a food chain are more vulnerable as they are slow breeders with lower populations making it harder to recover from population decline.

loss of shark populations

demand for shark fin soup has decimated shark populations, who due to being high in the food chain are unable to quickly recover. Their 70% decline in the last 50 years affects marine ecosystems, leading to overpopulation of prey species and disruption of ecological balance.

Loss of large mammals at the end of Pleistocene

The extinction of large mammals such as woolly mammoths and saber-toothed cats at the end of the Pleistocene epoch, the loss of which coincides with the arrival of modern man and habitat loss due to climate change and hunting pressures.

How temperature influences species coexistence

Temperature affects species coexistence by influencing physiological processes, resource availability, and interactions such as competition and predation, ultimately determining which species can thrive in a given environment. The rise or fall in temperature can alter habitat suitability, leading to shifts in the outcome of competition. This is an example of a realised versus fundemental niche.

Temperature dependent ecological processes

metabolic budgets of ectotherms, developmental rates, metabolic rate

Edge effect

The edge effect refers to the changes in population or community structures that occur at the boundary of two habitats, often resulting in increased biodiversity and different ecological dynamics compared to interior areas. The edge effect occurs when two distinct habitats meet, leading to unique ecological interactions and increased species diversity along the boundary compared to the interior habitats.

Edge effect and habitat fragmentation

fragmentation increases the proportion of edge to interior of a habitat , leading to higher biodiversity along edges but can also disrupt species' natural behaviors and processes.