Zooplankton as Beacons of Anthropogenic Climate Change Flashcards
(30 cards)
What does ‘anthropogenic climate change’ mean?
It refers to changes in the Earth’s climate system that result from human activities—primarily fossil fuel burning, deforestation, and industrial emissions—which increase atmospheric greenhouse gases such as CO₂.
What major environmental changes are caused by anthropogenic climate change?
These include global warming, ocean acidification, melting of polar ice, sea-level rise, ocean deoxygenation, and increased frequency of extreme weather events.
How does the ocean act as a buffer to climate change?
The ocean absorbs most of the excess heat trapped by greenhouse gases, reducing atmospheric warming but altering marine environments profoundly.
List six physical impacts of climate change on oceans.
- Warming and marine heatwaves
- Deoxygenation and OMZ expansion
- Ice cap and glacier melt
- Sea-level rise
- More extreme storms
- Ocean acidification
Why is temperature considered the most influential physical factor for marine ecosystems?
It controls metabolic rates, reproduction, geographic distribution, and species survival, thus directly shaping ecosystem structure and function.
How has the Southern Ocean warmed compared to the global average?
Since 1955, winter air temperatures have risen by more than 5°C in the Southern Ocean—more than double the global average—mainly affecting surface waters and polar ecosystems.
What are the two main causes of ocean deoxygenation?
- Natural aging of water masses—older waters like in the Pacific have less oxygen.
- Eutrophication—nutrient runoff causes algal blooms that decompose and consume oxygen, leading to hypoxic or anoxic conditions.
What are dead zones and their ecological consequences?
Dead zones are low-oxygen areas (hypoxic or anoxic) that can no longer support most marine life, leading to biodiversity loss and impaired fisheries.
What climate-driven changes are occurring in Arctic and Antarctic ice cover?
- Arctic: Decrease in sea ice thickness and extent.
- Antarctic: Regional variations in mass balance—some basins gain while others lose significant ice.
How is the ocean’s salinity pattern changing and why does it matter?
Freshening occurs near poles due to ice melt and precipitation, while subtropics show increased salinity. These changes alter ocean circulation and nutrient transport.
How does CO₂ contribute to ocean acidification?
The ocean absorbs about one-third of anthropogenic CO₂, which reacts with seawater to form carbonic acid, lowering pH and carbonate ion availability.
How does acidification affect marine calcifiers?
Organisms like pteropods suffer shell dissolution due to decreased carbonate ions, threatening their survival and the broader food web.
How was the link between marine life and climate change first established?
Using Continuous Plankton Recorder (CPR) data, scientists detected shifts in plankton communities corresponding with rising sea surface temperatures.
Why are zooplankton effective indicators of climate change?
Their temperature sensitivity, short life cycles, full exposure to environmental change, non-commercial status, and ecological ubiquity make them reliable biological sentinels.
What is poikilothermy and how does it affect zooplankton?
Poikilothermy means body temperature depends on the environment, making zooplankton’s metabolic and developmental rates highly sensitive to temperature shifts.
How does short lifespan enhance zooplankton sensitivity to climate change?
It allows rapid generational turnover, meaning populations can quickly reflect environmental changes through shifts in abundance, distribution, or timing.
What ecological roles enhance zooplankton’s importance beyond their own survival?
Many marine animals have zooplanktonic larval stages, and zooplankton are a key food source, linking primary producers with higher trophic levels.
What is a Thermal Window (TW)?
A range of temperatures within which an organism can maintain normal physiological functions. Outside this range, performance declines sharply.
How do performance curves look for poikilotherms?
They are unimodal: performance increases to an optimum and then declines rapidly beyond it.
What is the Arrhenius Breakpoint Temperature (ABT)?
A temperature at which enzymatic activity shifts significantly, indicating a physiological tipping point for the organism.
How is zooplankton fitness affected by warming?
Fitness depends on energy input (ingestion) versus energy loss (respiration). If warming increases respiration faster than ingestion, fitness declines.
How do different life stages respond to temperature?
Early stages often have narrower thermal windows and are more vulnerable. Later stages may be even more sensitive due to higher energy demands.
How does warming affect species coexistence?
It narrows the overlap in species’ thermal windows, reducing coexistence potential and possibly leading to competitive exclusion.
What happens when seasonal environmental cues become decoupled from biological cues?
Phenological mismatches occur—organisms may spawn or migrate at times that no longer align with optimal environmental conditions.
