Productivity

Why do we tend to use food webs rather than food pyramids in describing real communities?

A food web shows multiple food chains, multiple relationships and connections. This a more complicated but more realistic way of showing feeding relationships, as most organisms consume more than one species and are consumed by more than one species. a food pyramid takes the food chain but uses it to show how energy moves through a community. Because each organism uses some of the energy it received from the previous level for growth and other processes, the energy available to the next level is less (because some of that energy has been used). This is why we have more primary producers than carnivores.

Limiting Factors

A limiting factor is a physical or biological necessity whose presence in inappropriate amounts limits the normal action of organisms (primary productivity) Photosynthetic organisms need water, CO2, inorganic nutrients, and sunlight Water is not a limiting factor in the ocean CO2 is almost never limiting Sunlight can be limiting

What are some of the indirect ways to measure primary productivity?

By collecting bottles at different depths and adding either carbon-14 or measuring the oxyen produced. Using Carbon 14 is more accurate.

Photic Zone

CO2 is released by respiration and the breakdown of organic matter in the photic zone O2 is consumed by respiration and the breakdown of organic matter in the photic zone CO2 is removed from photic zone by photosynthesis

What is produced through primary productivity?

Carbs (organic carbon)

What is energy?

Living matter cannot function without energy Energy (E) is the capacity to do work

Can organism create new energy?

Living organisms cannot create new energy, but transform one kind of energy to a different kind All life activity is involved in energy transformation and transfer

Which organisms directly use solar energy? How?

Only 1 part in 2,000 of the light that reaches the Earth's surface is captured by organisms Light energy is trapped by chlorophyll in producers (some bacteria, algae, plants) and changed into chemical energy Chemical energy is used to build organic molecules, food Food is used by the producers or eaten by consumers (bacteria, fungi, animals)

The vertical distribution of nutrients in the water column is similar to the one of...

Oxygen

What are gross productivity and net productivity? EXAM QUESTION!!

Phytoplankton are "photoautotrophs," harvesting light to convert inorganic to organic carbon, and they supply this organic carbon to diverse "heterotrophs," organisms that obtain their energy solely from the respiration of organic matter. "Gross primary production" (GPP) refers to the total rate of organic carbon production by autotrophs "Net primary production" (NPP) is GPP minus the autotrophs' own rate of respiration; it is thus the rate at which the full metabolism of phytoplankton produces biomass. A certain amount of organic material is used to sustain the life of producers; what remains is net productivity.

Which organisms are responsible for primary productivity in the oceans?

Phytoplankton produce 90-96% of oceanic organic carbon Seaweeds contribute 2-5% Chemosynthetic organisms account for 2-5% - Total ocean productivity ranges 75-150 gC/m2/yr

Define primary productivity. What units are used to express it?

Primary productivity is the rate at which atmospheric or aqueous carbon dioxide is converted by autotrophs (primary producers) to organic material. Primary production via photosynthesis is a key process within the ecosystem, as the producers form the base of the entire food web, both on land and in the oceans. gC/m2/yr

How much mass and energy are transferred between trophic levels?

The total mass of consumers becomes smaller as energy flows toward the top of the pyramid (less but bigger animals) Only ~10% of the mass and energy from the organisms consumed is stored in the consumers

Seagrass beds

flowing plants live in sand water and muddy or sandy bottoms harbor many diff species ecosystem engineers high productivity

Primary Consumers

(herbivores): animals that feed on primary producers

Marine producers are

more efficient than terrestrial producers

Autotrophs

or primary producers: photosynthetic and chemosynthetic organisms (they make their own food)

Heterotrophs

organisms that must consume other organisms because they are unable to synthesize their own food molecules

Which of the following statements is FALSE?

oxygen is removed from photic zone by photosynthesis

Ocean Productivity

sugar cane - 3000gC/m2/yr temperate NA forest - 1500gC/m2/yr average open ocean - 100gC/m2/yr open tropical oceans - 18-50gC/m2/yr coral reefs - 1500-5000gC/m2/yr the amount of food marine organisms can produce and the number of organisms the ocean can support

Photosynthesis

the process through which light energy is used to synthesize molecules rich in stored energy

Chemosynthesis

the production of usable energy directly from E-rich inorganic molecules

Biolimiting nutrients

• Phytoplankton need inorganic nutrients to synthesize organic molecules and construct their skeletons or shells N, P, and Si are non-conservative nutrients that change in concentration with biological activity They are essential to the growth of phytoplankton. If these biolimiting nutrients increase in sea water, productivity increases. If they decrease in sea water, productivity decreases After a phytoplankton bloom (period of rapid growth) surface waters are often depleted of such nutrients The resulting low nutrient concentrations are the most important factors limiting the growth of marine producers

Light is more of a limiting factor for primary productivity...

at high latitudes

Compare marine and terrestrial primary productivity

Marine producers are much more efficient in their production of food The rapid turnover time indicates that nutrients cycle from producer to consumer and back much more quickly in marine ecosystems The total mass of a primary producer is assumed to be ~10 times the mass of the C it fixes

What is the ultimate source of energy for all organisms?

The main source of energy for living organisms is the Sun

What are some of the direct ways to measure primary productivity?

Various properties of the ocean can be measured to give an approximation of the amount of primary productivity Plankton nets are used to capture plankton. Analysis of the amount and type of organisms captured reveals much about the productivity of the area Carbon taken up by primary producers can be measured to calculate the rate of primary productivity using radioactive carbon Bottles can be used to measure the O2 produced by phytoplankton which indicates the amount of organic C synthesized Satellites can estimate the chlorophyll content of ocean water

Secondary Consumers

animals that feed on primary consumers

Primary Producers

are mostly chlorophyll-containing organisms