Antarctic benthic foraminifera austral summer 2001-2002 slideshare

  • View
    633

  • Download
    2

Embed Size (px)

Text of Antarctic benthic foraminifera austral summer 2001-2002 slideshare

  • Its a small worldor:

    Just because you cant see it doesnt mean its not there!

  • What are Protozoa ?Protozoa are single-celled organismsOne cell can perform all the living functions (feeding, movement, reproduction) multicellular organisms such as worms or humans - need a large number of cells forProtozoa have developed many different ways of life (parasitic, free-living) in terrestrial and marine environments They are everywhere!

  • What are Foraminifera ?Foraminifera are a group of Protozoa that are exclusively marineThere are pelagic and benthic ForaminiferaThey occur everywhere in the oceansForams are particularly abundant in low temperature environments e.g. the deep sea and polar seas they appear to be the most common group of protozoa in Antarctic benthic environments!

  • There are different kinds of Foramssome Forams are soft-bodied they have an organic wall

  • agglutinated Foraminifera make their tests out of sediment particles

  • calcareous Foraminifera have shells made from calcium carbonate

  • Investigates the impact of food input on the benthic environment and the organisms living on the Western Antarctic Peninsula shelf.FOODBANCS: Food for the Benthos on theAntarctic Continental Shelf PIs Craig Smith, UH and Dave DeMaster, NCSU1999-2000

  • Foraminifera show a strong specific response to pulsed food inputThey are able to ingest a large part of freshly deposited organic matter quicklyForams respond directly to food availability - other groups, e.g. nematode or polychaete worms, show a delayed response or no response at all.Why Forams?

  • Whats special about Forams?Being Protozoa, they can reproduce much faster than metazoa (asexual multiple fission)A solid calcareous or agglutinated test provides protection against environmental factors and (arguably) predatorsForams have a high potential turnover rate - they can burn a high amount of organic matter in a short period of timeTheir reticulopodial net is a highly efficient food gathering apparatus (conveyor-belt movement)

  • FOODBANCS:Abundances of Foraminifera in the >300mm size classAgglutinated foraminifera are more abundant than metazoa in the macrobenthic size class (>300 mm) in the topmost sediment layer (0-0.5 cm)Metazoan organisms are more abundant in the 0.5-1.0 cm layer belowOrganic matter from the spring phytoplankton bloom is most likely be processed to a great extent by foraminifera before metazoan organisms can get to it

  • Its not just about quantity!

  • Food thats good for you(and other critters):Polyunsaturated Fatty Acids (PUFAs)PUFAs are a group of fatty acids components of fats and oils which are only produced by a small number of organisms, but needed by manyIn the marine environment, photosynthetic organisms such as diatoms and flagellates produce PUFAs in high amounts

  • What are PUFAs good for?PUFAs are important for certain cell membrane properties, e.g. preservation of membrane fluidity under high pressure or low temperature (deep-sea, Antarctic!!)Certain fish species need PUFAs in neural tissue (retinas and brain)PUFAs are precursors for a number of animal hormonesPhytoplankton with high PUFA content supports higher zooplankton biomass the availability of PUFAs is a limiting factor

  • What happens to these fatty acids?

  • FOODBANCS:results from lipid analysisThree of the most abundant species of Foraminifera feed very selectively on certain components of freshly deposited organic matterThere is some indication that certain species ingest and decompose that part of the phytodetritus which is rich in PUFAs and thus make it unavailable for other organisms

  • And now

  • Objectives at PalmerTime series: development of fatty acid profiles of an abundant calcareous foraminiferal species Globocassidulina crassa - in January-FebruaryFeeding experiments on G. crassa decomposition of the high quality part of phytoplankton?

    Suhr & Pond (2006) Deep Sea Research Part II, Volume 53, Issues 8-10

  • SoForaminifera have a potentially very important and complex role in areas with a pulsed food input such as the Antarctic.

  • Suhr et al. (2003) MEPS Vol. 262: 153162

Recommended

View more >