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  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/m 2 /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.  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/m 2 /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.  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.  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.  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/m 2 /yr in the marine environment  highest in estuaries  lowest in the open ocean.  Primary productivity varies from 25 to 1250 gm C/m 2 /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.  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.  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/m 2 /yr  Nutrients wash in from the land  Tide- and wave- generated turbulence recycle nutrients from the bottom water.  Continental shelves display moderate productivity between 50 and 200 gm C/m 2 /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.  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.  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

 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  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.  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.  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  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).  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 tide  Aureococcus anophagefferens  Does not create toxins  However, they do damage seagrasses and seabeds  Led to economic losses - millions of dollars  Brown tide  Aureococcus 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  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.  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  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  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 ".  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.  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.  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.