Energy Capture and Allocation Flashcards
Primary Production
The formation of organic matter through the trapping of light energy and assimilation of inorganic elements
Mangroves, Salt Marsh, and Seagrass Coverage
These ecosystems cover less than 0.5% of the marine area yet account for between 50 and 71% of carbon storage in marine sediments
Primary Producers of the Ocean
Seaweeds (macro-algae), seagrasses, and microscopic algae (phytoplankton) and bacteria
Algal Bloom
When phytoplankton rapidly proliferate under proper light and nutrient conditions
Needs of Photosynthetic Organisms
Light, carbon dioxide, oxygen, macro-nutrients (phosphate, nitrate, silicate)
Oligotrophic
Low concentrations of nutrients for algal blooms and low primary productivity (<100 g carbon m-2 per year)
Eutrophic
High concentrations of essential nutrients for algal blooms and high primary productivity (300 to 500 g carbon m-2 per year)
Mesotrophic
In between eutrophic and oligotrophic waters (100 to 300 g carbon m-2 per year)
Eutrophication
Rapid increase in the primary productivity of an area, often caused by a rise in an essential inorganic nutrient like nitrogen or phosphorus
Biomass-Limiting
The nutrients are so exhausted that no more mass can be produced
Rate-Limiting
The nutrients limit the rate of new biomass production by their rate of supply
Diffusive Boundary Layer
Surrounds each cell or surface in water and restricts the molecular diffusion and the movement of water // Smaller cells have a thinner/lower DBL and have a physiological advantage in low nutrient waters
HNLC Areas
High nutrient, Low-chlorophyll areas are potentially limited by light or depletion of standing stocks, yet more likely by the absence of iron (a necessary micro-nutrient for primary production)
Succession of Phytoplankton Species
Controlled by a complex mosaic of factors, like temperature, irradiance, growth rates, and nutrient supply
Governing Factors of Marine Primary Production
Light, nutrients, stability, and mixing
Tropical and Subtropical Areas (PP)
Normally have permanent thermal stratification and less mixing, so more nutrient-limiting, resulting in lower levels of productivity that are fairly consistent
Polar Areas (PP)
Significant mixing which brings good nutrient concentrations, yet more light-limiting through irradiance, and limited times of production
Temperate Waters (PP)
Seasonal fluctuation of primary productivity due to the complex range of factors, so low in the summer/winter and higher in the spring/summer
Coriolis Effect
Deflects currents northwards in the northern hemisphere and southwards in the southern hemisphere, drawing surface waters away from the equator and allowing for upwelling to occur there
Coastal Waters // Continental Shelf Waters (PP)
These waters have the highest primary productivity, shallow enough for good light and receive nutrients from river sources
Marine and Terrestrial Primary Production
Roughly the same, at 50 Pg of carbon each per year
Primary Production
Usually defined by the amount of bacterial, algal, or plant biomass built up through the process of photosynthesis over time
Net Primary Production
The total photosynthetic carbon assimilation minus respiration carbon losses
Mass Balance
There is a net input of around 20 Tmol carbon per year to the oceans, and the oceans are probably net heterotrophic, with respiration exceeding photosynthesis by about 0.2%
Redfield Ratio
A 7:1 relative proportion of nitrogen and phosphorus needed by phytoplankton
Trophic Levels
Producers (autotrophs) - Primary Consumers (heterotrophs, for all following levels) - Secondary Consumers - Tertiary Consumers - Quaternary Consumers (also Decomposers)
Food Chains
Show a relationship from primary producers to quaternary consumers, via the energy flows and loss of energy upwards (linear model)
Food Webs
In addition to showing connections of energy, includes all the relationships, including decomposers, detritivores, scavengers as well
Quantitative Measures in Food Webs
Connectance, linkage density, and chain length (and mean)
Connectance
The measure of the proportion of links in a food web (the number of observed links divided by the total number of species squared)
Linkage Density
The number of observed links divided by the number of total species (basically gives you the average number of links)
Chain Length
The number of trophic levels in each chain (can add up these numbers and then divide by the number of chains)
Continual Input of Small Nutrient Doses
Competitive species are favored, domination by a very few species, relatively constant biomass
Occasional Input of Large Nutrient Doses
Biomass may fluctuate widely, continually altering species composition
Dietary Guilds
A way of classifying species in each trophic level by their dietary habits
Dead Zones
Occur because of eutrophication which may lead to algae blooms where the end result is low O2 areas (hypoxia) or no O2 areas (anoxia) because the bacteria use up all the oxygen during decomposition
Causes of Increasing Eutrophication
Increased nutrient pollution, sea surface warming, ocean acidification, and reduced water flow
Grazing
Phytoplankton are often consumed by a range of grazing zooplankton // this can lead to “clear-water phases” when they eat all of the algae
Detritus
Most phytoplankton biomass settles to lake or sea beds
Diadromous Fish
Fish that spend part of their lives in freshwater and part of their lives in marine waters; anadromous if mostly salt [salmon], catadromous if mostly fresh [herring]
Potadromous Fish
Migration takes place entirely in freshwater systems, e.g. catfish
Oceanodromous Fish
Migration takes place entirely in the sea, e.g. bluefin tuna
Tidal Migrations
Smaller scale movements over shorter periods in up-shore or down-shore directions, for food, to minimize predation risk, for reproduction // Can be intertidal migration or selective tidal-stream transport
Primary Producers of the Ocean
Seaweeds (which are macro-algae, not flowering plants), seagrasses, microscopic algae and bacteria, mangroves, etc
Phytoplankton Cells
Micro-algae that generate most of the primary production in the oceans
Prokaryotic Photosynthetic Organisms
Much smaller than microphytoplankton, and include organisms like cyano-bacteria and pelagic prochlorophytes
Picoplankton
Very small, from 0.2 to 2.0 um // thus the prokaryotic photosynthetic organisms fit into this
Photoautotrophs
Algae (micro- and macro-) and cyanobacteria // Use light for their energy source and carbon dioxide (in various forms) to produce new organic matter
Anticyclonic Gyres
CW in northern hemisphere, CCW in southern // regions of low primary production because the thermocline is deepened, with water moving toward the center of the gyre
Cyclonic Gyres
CCW in northern hemisphere, CW in southern // mix water below the thermocline into surface waters, so support higher rates of primary production
Marine Snow
Zooplankton are a vector for transport of organic material from the surface to the depths, and detritus that falls out of the euphotic zone is “marine snow”
Species of Oligotrophic Waters
Small phytoplankton species that have a greater surface area:volume ratio, enabling more molecular diffusion crucial for the resupply of nutrients
Diffusion-Limitation
For organisms >100 um in diameter, movement through water can lower the DBL and increase nutrient diffusion // For macro-algae and seagrasses, ridges and ruffled blades increase the motion of water around the DBL
Main Growth-Limiting Nutrients (marine)
Nitrogen and phosphorus
Main Growth-Limiting Nutrients (freshwater)
Nitrogen and phosphorus, yet mostly phosphorus
