Lecture 13- Marine food webs Flashcards
What is the big difference in primary producers on land and in the sea?
-on land they are large (trees) -in the seas they are unicellular (phytoplankton)
How does a food chain work?
-1. Phytoplankton 2. Herbivorous zooplanktin 3. carnivorous zooplankton 4. small fish 5.larger fish 6- seal 7. killer whale
What is the difference if trophic levels on land and in the sea?
-on land usually up to 3 or 4 -in the sea can reach almost 7(not really)
What do all organisms need to grow and thrive?
-energy -electrons -carbon (plus associated nitrogen, phosphorus and sulphur)
What are autotrophs?
-synthesize their own complex carbon compounds.
What are phototrophs? (subdivision of autotroph)
-such as phytoplankton use energy from sunlight plus carbon dioxide and water to synthesize complex carbon compounds
What are chemotrophs? (subdivision of autotrophs)
-use energy from inorganic chemical compounds, such as methane, hydrogen sulphide, or reduced iron plus carbon dioxide or some organic carbon to synthesize complex carbon compounds
What are mixotrophs?
-are organisms that can use energy from both sunlight and chemical compounds.
What are heterotrophs?
are organisms that must eat other organisms to obtain complex carbon compounds. Some are able to use sunlight or inorganic compounds for energy, others must use organic carbon compounds for energy. People are heterotrophs that get complex carbon compounds and energy from other organisms.
What are bacteroivores?
-eat bacteria
How do we determine food web structure?
- Stomach content analyses (traditional) - Stable carbon and nitrogen isotope analysis -observation (put camera on)
Who are the primary producers in the sea? (trophic level 1)
-phytoplankton (autotrophic)
Who are the primary consumers in the sea? (trophic level 2)
-zooplankton
Who are the secondary consumers in the sea? (trophic level 3)
-predatory zooplankton
Who are the tertiary consumers in the sea? (trophic level 4)
-filter feeders
Who are the 4th, 5th and 6th level consumers?
-predators
What are the 3 characteristics of marine food webs?
• Marine food webs are complex •Species may alter levels in a food web at different life cycle stages •Consumers often feed at multiple levels in a food web
Who are the primary producers?
- phytoplankton, seaweeds, plants (sea grass), chemotrophic bacteria
How much do the diatoms contribute to ocean primary productivity?
- contribute about 60 per cent of the primary productivity in the oceans. - 200,000 different species diatoms ranging is size from micrometres to millimetres
How much do the Coccolithophores (haptophytes) contribute to ocean phytoplankton biomass?
- contribute about 15 per cent of the average oceanic phytoplankton biomass to the oceans.
What types of zooplankton are the primary consumers?
-Single-celled animals such as ciliates or amoeboids that never grow large. -Copepods about 7500 species, extremely abundant. Biomass ∼ 0.8 and 2.0 billion tons -Shrimp e.g. Krill, ∼ 500 million tons in the southern ocean -Larval forms of barnacles, molluscs, fish, and jellyfish, all of which grow to be much larger animals
What types of filter feeders are the secondary consumers?
-Shrimp and krill. -Immature stages of larger animals such as jellyfish and fish. -Small planktivorous fish such as sardines, anchovies, mackerel and herring,highly abundant and a principal target of modern fisheries. -Some whales (e.g. blue whale)
What types of carnivores are the tertiary consumers?
=Jellyfish = Cephalopods (squid and octopus). -Predatory fish= enormous diversity
What sort of predators are the 4th, 5th and 6th level consumers?
1.Large predatory fish such as sharks, tuna, and mackerel. 2.Marine mammals - seals, walruses, dolphins 3.Birds such as pelicans, albatross, penguins and skua. 4.Jellyfish Cephalopods (squid and octopus). Predatory fish - enormous diversity 5.People, the dominant top predator.
