Tema 3 Flashcards
What are the key features of the Epipelagic Zone?
Primary source of food and energy export in marine ecosystems.
Suspension feeders dominate.
Home to large predators and diverse organisms.
What are the characteristics of phytoplankton?
Predominantly unicellular organisms.
Responsible for 95% of oceanic photosynthesis and half of the world’s primary production.
Contribute to half of atmospheric oxygen (O₂).
What are the key characteristics and ecological roles of diatoms?
~12,000 species (half marine).
Unicellular (2–2000 µm), some form aggregates.
Account for ~40% of oceanic primary productivity.
Major prey for mesozooplankton.
Thrive in temperate, polar, and nutrient-rich waters.
Made of silica, contributing to diatomaceous earth.
What are the key characteristics and ecological roles of dinoflagellates?
Size: 80-500 µm.
~1200 species, mostly marine.
Capable of migration and mobility.
Some cause red tides and produce toxins.
Thrive in nutrient-poor tropical waters.
What causes red tides and what are their ecological impacts?
Caused by dinoflagellates and other phytoplankton.
Some species produce toxic substances.
Resting spores/cells provide resistance to light, temperature, salinity, and nutrient changes.
What is the significance of picoplankton in marine ecosystems?
Size: 0.6–0.8 µm.
Major contributor to primary production in epipelagic zones.
Can reach up to 100 million per liter.
Cyanobacteria, such as Synechococcus, are important for photosynthesis.
What are the key groups of nanoplankton?
Size: 3-10 µm (up to 100 µm).
Includes coccolithophores, silicoflagellates, diatoms, and dinoflagellates.
Important primary producers, especially in neritic zones.
How are zooplankton classified?
Holoplankton: Entire life cycle in plankton.
Meroplankton: Planktonic only during certain life stages.
Protozoa: Unicellular, some photosynthetic.
Major contributors to primary production and microbial loops.
What is the role of copepods in marine ecosystems?
Represent ≥ 70% of zooplankton communities.
Primary consumers of phytoplankton.
Can filter thousands of diatoms daily.
Important in zooplankton biomass.
Why do marine species migrate vertically?
To avoid predation and conserve energy.
Helps reduce metabolism and avoid toxins produced by phytoplankton.
Migrating species include nektonic species like fish.
What are the characteristics of energy flow in marine ecosystems?
Marine ecosystems have longer trophic levels compared to other ecosystems.
Tropical waters typically have 5-6 trophic levels, while cold waters have fewer.
Herbivores make up more than 20% of the biomass, carnivores over 10%.
What is the microbial loop, and why is it important?
Involves nano- and picophytoplankton in primary production.
Phytoplankton produce MOD (Dissolved Organic Matter) that is recycled in the system, supporting the microbial loop.
What factors control primary production in marine ecosystems?
Light and nutrients (N and P).
The Redfield Ratio (C:N:P = 106:16:1).
Critical depth where light penetration supports photosynthesis.
How does primary production occur in polar and temperate waters?
Enhanced by overturn and mixing, bringing nutrients to the surface.
Nutrient-rich zones have high primary production.
How does primary production differ between neritic and oceanic waters?
Neritic (coastal) waters are more productive due to proximity to land and nutrient input.
Oceanic waters are less productive but can experience upwelling, which brings nutrients.
