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(Bio) Planktons: Chemistry of Fossil Plankton Shells

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PostPosted: Wed Apr 05, 2006 8:16 am    Post subject: (Bio) Planktons: Chemistry of Fossil Plankton Shells Reply with quote

Chemistry of Fossil Plankton Shells Precise Indicator of Depth Habitat
European Geosciences Union
Saturday, 01 April 2006

New geochemical techniques now make it possible to precisely determine the water depths at which plankton used to live. This opens new opportunities for palaeoceanographic research.

Marine geologists often use the fossil remains of calcareous marine zooplankton (planktic foraminifera) to obtain information on the past ocean. The chemistry of the tiny shells of these organisms provides important information on, for example, the ocean’s temperature, density stratification, ice volume or may be used to reconstruct past changes in biological productivity or CO2. It is often assumed that species grow their calcite shells at a fixed level in the water column.

Using plankton tows, Iris Wilke (Geosciences Department, University of Bremen) and Frank Peeters (Vrije Universiteit, Amsterdam) have collected living planktic foraminifera at various locations in the Atlantic and Indian Oceans. Their results, presented on a poster at the EGU 2006, show that the shell geochemistry does not reflect a single depth level or a fixed temperature. They use an oxygen isotope mass-balance model to precisely quantify the depth habitat of ten species of modern planktic foraminifera which are frequently used in palaeo-oceanographic studies. The model fits to field data clearly indicate species-specific and species-characteristic depth integrated growth patterns.

Wilke and Peeters, show that some species grow their calcite at very shallow levels in the water column (i.e. within the surface mixed layer), while other species may continue to grow in water layers down to hundreds of metres below the sea surface, much deeper than previously assumed. Considering the chemisty of shells of different species that have grown over different parts of the water column, the authors suggest that their findings may be used to potentially unravel the density structure of the past water column and hence density driven circulation.


Questions to explore further this topic:

An introduction to marine biology


The ocean food web

What are planktons?

What are phytoplanktons?

Images of phytoplankton

Species of phytoplanktons

Phytoplanktons in fish ponds

What are algae?

What are zooplanktons?

Images of zooplanktons

How are zooplanktons identified?


Zooplanktons and coral reefs

Planktons in Southeast Asia

Planktons in the Black Sea

Planktons and red tide

What are holoplanktons?

What are meroplanktons?

Ocean biology and chemistry

Shells, history, climate change,00.html

Chemistry of shells


The Earth Through Time (Fossils)



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PostPosted: Thu Aug 31, 2006 2:58 pm    Post subject: NASA study solves ocean plant mystery Reply with quote

NASA/Goddard Space Flight Center
31 August 2006

NASA study solves ocean plant mystery

A NASA-sponsored study shows that by using a new technique, scientists can determine what limits the growth of ocean algae, or phytoplankton, and how this affects Earth's climate.

Phytoplankton is a microscopic ocean plant and an important part of the ocean food chain. By knowing what limits its growth scientists can better understand how ecosystems respond to climate change.

The study focused on phytoplankton in the tropical Pacific Ocean. It is an area of the ocean that plays a particularly important role in regulating atmospheric carbon dioxide and the world's climate. This area of the ocean is the largest natural source of carbon dioxide to the atmosphere.

"We concluded that nitrogen is the primary element missing for algae growth and photosynthesis in the northern portion of the tropical Pacific, while it was iron that was most lacking everywhere else," said Michael J. Behrenfeld, an ocean plant ecologist from Oregon State University, Corvallis, Ore.

Scientists determined when phytoplankton is stressed from lack of iron; it appears greener, or healthier than they really are. Normally, greener plants are growing faster than less green plants. When iron is lacking, enhanced greenness does not mean phytoplankton are growing better. They are actually under stress and unhealthy. These conclusions solved the mystery why healthy looking phytoplankton are actually not so healthy.

"Because we didn't know about this effect of iron stress on the greenness of algae or phytoplankton before, we have always assumed that equally green waters were equally productive," Behrenfeld said. "We now know this is not the case, and that we have to treat areas lacking iron differently."

For the tropical Pacific, correction for this "iron-effect" decreases scientists' estimates of how much carbon ocean plants photosynthesize for the region by roughly two billion tons. This figure represents a tremendous amount of carbon that remains in the atmosphere that scientists previously thought were being removed.

The results about the false health of phytoplankton allow scientists using computer models to re-create the movement of carbon around the world much more accurately. Resource managers will become more knowledgeable about where carbon is going and the impact of recreational, industrial or commercial processes that use or produce carbon. Researchers better understand the Earth as an ecosystem, and can incorporate these findings in future modeling, analysis and predictions.

While satellite data from NASA's Sea-viewing Wide Field-of-view Sensor played an important part in the study, the real cornerstone of the discovery was ship-based measurements of fluorescence.

Fluorescence occurs when plants absorb sunlight and some of that energy is given back off again as red light. Scientists looked at approximately 140,000 measurements of fluorescence made from 1994 to 2006 along 36,040 miles of ship tracks. They found that phytoplankton give off much more fluorescence when the plants do not have sufficient iron. It is this signal they used to fingerprint what parts of the ocean are iron-stressed and what parts are nitrogen-stressed.

It is important that scientists understand how ocean plants behave because all plants play a critical role in maintaining a healthy planet. Plants annually take up billions of tons of carbon dioxide from the atmosphere through photosynthesis and use this carbon to create the food that nearly all other organisms on Earth depend on for life.

Nutrients that make ocean plants thrive, such as nitrogen and phosphate, mostly come from the deep parts of the ocean, when water is mixed by the wind. Iron also can come from dust blowing in the air.

Approximately half of the photosynthesis on Earth occurs in the oceans, and the remainder on land. Ocean and land plants share the same basic requirements for photosynthesis and growth. These requirements include water, light and nutrients. When these three are abundant, plants are abundant. When any one of them is missing, plants suffer.

An article on this technique appears in a recent issue of Nature. For images related to this research, visit:
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PostPosted: Fri Jun 15, 2007 1:03 pm    Post subject: Marine phytoplankton changes form to protect itself from dif Reply with quote

Marine phytoplankton changes form to protect itself from different predators
Single-celled transformers
15 June 2007
Georgia Institute of Technology

A tiny single-celled organism that plays a key role in the carbon cycle of cold-water oceans may be a lot smarter than scientists had suspected.

In a paper published June 11 in the online version of Proceedings of the National Academy of Sciences, researchers report the first evidence that a common species of saltwater algae – also known as phytoplankton – can change form to protect itself against attack by predators that have very different feeding habits. To boost its survival chances, Phaeocystis globosa will enhance or suppress the formation of colonies based on whether nearby grazers prefer eating large or small particles.

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PostPosted: Sat Dec 22, 2007 6:29 am    Post subject: The Institute for the Promotion of the Less than One Millime Reply with quote

The Institute for the Promotion of the Less than One Millimeter

For several centuries artists have depicted the human figure, still-lifes, landscapes or non-figurative motives. One subject has been widely neglected all those years: Micro organisms!

The Micropolitan Museum finally exhibits these often overlooked works of art which are only visible with the aid of the microscope. Curator Wim van Egmond has collected the finest microscopic masterpieces nature has ever produced during eons of natural selection.
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