Primary Productivity in the Ocean

Lesson 13 and 14

Engage

Some of the most important organisms in aquatic environments are microscopic

Primary productivity in the oceans is greater than on land

Variation of Productivity Across Marine Ecosystems

Primary production is the total amount of carbon (C) in grams converted into organic material per square meter of sea surface per year (gm C/m2/yr).

Factors that limit plant growth and reduce primary production include solar radiation and nutrients as major factors and upwelling

turbulence

grazing intensity

turbidity as secondary factors.

Variation of Productivity

Productivity varies greatly in different parts of the ocean in response to the availability of nutrients and sunlight.

In the tropics and subtropics sunlight is abundant, but it generates a strong thermocline that restricts upwelling of nutrients and results in lower productivity.

High productivity locally can occur in areas of coastal upwelling, in the tropical waters between the gyres and at coral reefs.

Variation of Productivity

In temperate regions productivity is distinctly seasonal.

Polar waters are nutrient-rich all year but productivity is only high in the summer when light is abundant.

What Affects Productivity

Upwelling and turbulence can return nutrients to the surface.

Over-grazing of autotrophs can deplete the population and lead to a decline in productivity.

Turbidity reduces the depth of light penetration and restricts productivity even if nutrients are abundant.

Global Patterns of PP

Primary productivity varies from 25 to 1250 gm C/m2/yr in the marine environment highest in estuaries

lowest in the open ocean.

Global Patterns of PP

Although PP low in the open ocean, it has the greatest biomass productivity because of its enormous size.

In the open ocean the food chains are longer and energy transfer is low, so fish populations are small.

Global Patterns of PP

In the open ocean productivity distribution resembles a “bull’s eye” pattern

Lowest productivity in the center and highest at the edge of the basin.

Water in the center of the ocean is a clear blue because it is an area of downwelling

Above a strong thermocline and has almost no biological activity.

Global Patterns in PP

Continental shelves display moderate productivity between 50 and 200 gm C/m2/yr Nutrients wash in from the land Tide- and wave- generated turbulence recycle

nutrients from the bottom water.

Global Patterns of PP

Polar areas have high productivity because there is no pycnocline to inhibit mixing.

Global Patterns of PP

Equatorial waters have high productivity because of upwelling.

Energy Transfer through Food Chains

Biomass is the quantity of living matter per volume of water.

With each higher trophic level – Size of organisms generally increases

Reproductive rate, number, and the total biomass decrease.

Energy Transfer through Food Chains

The two major food chains in the ocean Grazing food chain

Detritus food chain - non-living wastes form the base of the food chain.

Only about 10-20% of energy is transferred between trophic levels

Produces a rapid decline in biomass at each successive trophic level.

Many Marine Producers

Cyanobacteria are some of the tiniest phytoplankton, but are also very important. They are believed to be Earth's first producers.

Like any other type of phytoplankton, coccolithophores are one-celled marine organisms that live in large numbers throughout the upper layers of the ocean. Coccolithophores surround themselves with a microscopic plating made of calcite, the mineral that makes up limestone. These scales, known as coccoliths, are shaped like hubcaps and are only three one-thousandths of a millimeter in diameter.

Diatoms

Coccolithophores

Cyanobacteria

Diatoms

Diatoms Eukaryotic algae Common type of

phytoplankton Unicellular or colonies Primary producers in the food

chain Over 200 genera of living

diatoms, and approximately 100,000 species

Found in freshwater and marine environments

Diatom cells are contained within a unique silica cell wall called frustules, comprising two separate shells two shells overlap one other

like the two halves of a petri dish

•Silica is made in the cell and then extruded to the cell exterior and added to the wall.

Reproduction

When a diatom divides to produce two daughter cells, each cell keeps one of the two halves and grows a smaller half within it.

After each division cycle the average size of diatom cells in the population gets smaller.

When a certain minimum size is reached, they reverse this decline by expanding in size to give rise to a much larger cell Caused by sexual reproduction.

Ecology

Diatoms produce an estimated 20% to 25% photosynthesis on the planet

A major food resource for marine and freshwater microorganisms and animal larvae

A major source of atmospheric oxygen.

Nanotechnology

The deposition of silica by diatoms may also prove to be of utility to nanotechnology

Diatom cells manufacture different shapes and sizes, potentially allowing diatoms to manufacture micro- or nano-scale structures which may be of use in a range of devices, including drug delivery

Algal blooms

Although microscopic, these organism can reproduce at a rapid pace and become visible

This is called an algal bloom.Some release harmful toxins that

can be deadly to marine organisms and humans.

These are called harmful algal blooms (HABs).

Diatom Algal Blooms - Article

Brown tideAureococcus anophagefferens

Does not create toxins

However, they do damage seagrasses and seabeds

Led to economic losses - millions of dollars

Harmful Algal Blooms

The first reported outbreak of domoic acid poisoning occurred in 1987

Shellfish from Prince Edward Island, Canada were consumed

Harmful Algal Blooms

3 people died and over 100 people developed various toxic symptoms.

Domoic acid was found to be produced by the diatom Pseudo-nitzschia multiseries.

Domoic Acid

Most unusual symptom is loss of memory

Exposure is called Amnesic Shellfish Poisoning

Interferes with nerve signal transmission

Dinoflagellates

Unicellular protists which exhibit a great diversity of form

The largest, Noctiluca, may be as large as 2 mm in diameter!

Many are photosynthetic

Some species are capable of producing their own light through bioluminescence, which also makes fireflies glow.

Some are parasites

Dinoflagellates

The most dramatic effect of dinoflagellates are the coastal marine species which "bloom" during the warm months of summer.

These species reproduce in such great numbers that the water may appear golden or red, producing a "red tide".

Red Tide

Dinoflagellates

When this happens many kinds of marine life suffer, for the dinoflagellates produce a neurotoxin which affects muscle function in susceptible organisms.

Humans may also be affected by eating fish or shellfish containing the toxins.

Dinoflagellates

The resulting diseases include ciguatera (from eating affected fish) and paralytic shellfish poisoning, or PSP (from eating affected shellfish, such as clams, mussels, and oysters); they can be serious but are not usually fatal.

Type 2: Red tide

Caused by the dinoflagellate Karenia brevis.

Produces a suite of toxins called Brevetoxins.

Occurs in the Gulf of Mexico and various other places.

Can blow onshore to affect humans with respiratory illnesses.