Zooplankton and climate change Flashcards
(23 cards)
What are the grand challenges in marine science?
Climate change (warming, acidification, deoxygenation).
Biodiversity loss and shifts in ecosystem services.
Sustainable use of marine resources.
Addressing these requires aligning global marine research priorities.
Why are zooplankton good indicators of anthropogenic climate change (ACC)?
They have fast life cycles and respond quickly to environmental changes.
Sensitive to temperature, food availability, and ocean circulation.
Reflect changes in distribution, size, phenology, and abundance.
How is ACC affecting the distribution of zooplankton species like Calanus (explain)?
C. finmarchicus (cold-water) is declining and moving north.
C. helgolandicus (warm-water) is increasing and shifting poleward.
Climate indices (like NAO) and rising SST are driving these changes.
What are the ecological implications of shifting of each Calanus species distributions?
C. finmarchicus: Large and lipid-rich, key prey for many fish.
C. helgolandicus: Smaller, less energy-dense → weaker food chain support.
Affects fish recruitment and overall energy flow in ecosystems.
What is the role of the Subpolar Gyre in zooplankton ecology?
Controls temperature and nutrient distribution in the North Atlantic.
Changes in gyre strength alter sea surface temperature (SST) and primary productivity.
Abundance of C. finmarchicus correlates with gyre variability.
How does ocean warming impact non-native species in marine environments?
Warmer waters promote expansion of warm-water and alien species.
Enclosed seas (e.g. Eastern Mediterranean) show sharp increases (150% rise in non-native zooplankton since the late 1990s).
How is zooplankton biodiversity changing globally?
Biodiversity peaks are shifting poleward.
Temperate zones are seeing an influx of subtropical species.
More species = generally smaller average body size.
What is the relationship between temperature and zooplankton body size?
Inverse correlation: Warmer areas have smaller zooplankton.
Small species dominate in high-diversity, warm waters.
What ecological rules explain size changes in warming oceans?
Bergmann’s Rule: Species tend to be smaller in warmer regions.
James’ Rule: Individuals within a species are smaller in warm areas.
Temperature-Size Rule (TSR): Higher temperatures → faster development but smaller adults.
What mechanisms drive the Temperature-Size Rule in zooplankton?
Direct: Fast development reduces time to grow large.
Indirect: Warmer waters → more stratification → lower nutrient mixing → smaller, less nutritious phytoplankton.
What changes were observed in Long Island Sound’s zooplankton community?
SST rise over decades reduced Acartia copepod size.
Cyclopoids like Oithona spp. became more abundant due to thermal tolerance and smaller size.
How has phenology (seasonal timing) of zooplankton changed due to ACC?
Species now peak earlier in the season.
Pacific example: Warm PDO phase → earlier copepod blooms.
North Sea: Multiple species show earlier seasonal peaks since the 1950s.
What are the potential ecological risks of phenological shifts?
Trophic mismatches (e.g., zooplankton peaking before fish larvae hatch).
Disrupted food availability for higher trophic levels.
Are zooplankton becoming more or less abundant with climate change?
Abundance trends are variable and not always directly linked to temperature.
Influenced by multiple factors like nutrients, circulation, and predator presence.
What changes have occurred in zooplankton community composition?
Central North Sea: Increase in meroplankton (e.g. echinoderm and decapod larvae).
Likely due to warming-induced stratification and enhanced reproduction.
What is a marine regime shift?
A long-term, large-scale change in ecosystem structure and function.
Often triggered by climate change and reinforced by internal feedbacks.
Difficult to reverse once established.
Describe the North Sea regime shift example.
Cold regime (1962–1982): Low diversity, cold-water species.
Warm regime (1985–1999): High diversity, warm-water species.
Fish impacts: Flatfish thrived in warm conditions. Gadoid fish declined due to prey (C. finmarchicus) loss.
Are regime shifts local or widespread?
Often hemispheric or global in scale.
Linked to sea surface temperature anomalies, salinity shifts, and atmospheric patterns (e.g., Arctic Oscillation).
What biological responses occur after regime shifts?
Declines in large copepods.
Changes in fish recruitment.
Altered timing and intensity of phytoplankton blooms.
Trophic cascades through the food web.
What broader physical and chemical changes are caused by ACC in oceans?
Warming: Reduces habitat for cold-water species.
Acidification: CO₂ uptake lowers pH, harms calcifiers (e.g. pteropods).
Sea Level Rise: Erosion, flooding, habitat loss.
Sea Ice Loss: Alters light regimes and polar productivity.
What’s the difference between ecosystem structure and function?
Structure: What species are present, how they are arranged.
Function: Energy flow, nutrient cycling, productivity.
ACC impacts both, reducing resilience and stability.
What ecosystem services are at risk from climate-induced regime shifts?
Fisheries productivity.
Coastal protection (e.g., reefs, salt marshes).
Biodiversity maintenance.
Carbon cycling and sequestration.
Why are regime shifts hard to reverse?
Ecosystems develop internal feedback loops (e.g., predator-prey, nutrient cycling).
Once thresholds are crossed, systems stabilize in new states.
