Antarctic benthic foraminifera austral summer 2001-2002 slideshare

It’s a small world…

or:

Just because you can’t see it doesn’t mean it’s not there!

What are Protozoa ?• Protozoa are single-celled organisms• One cell can perform all the living functions

(feeding, movement, reproduction) multicellular organisms – such as worms or humans - need a large number of cells for

• Protozoa 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 marine

• There are pelagic and benthic Foraminifera• They occur everywhere in the oceans• Forams 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 Forams…

…some 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 ShelfPIs Craig Smith, UH and Dave DeMaster, NCSU

1999-2000

• Foraminifera show a strong specific response to pulsed food input

• They are able to ingest a large part of freshly deposited organic matter quickly

• Forams respond directly to food availability - other groups, e.g. nematode or polychaete worms, show a delayed response or no response at all.

Why Forams?

What’s 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) predators

• Forams have a high potential turnover rate - they can ‘burn’ a high amount of organic matter in a short period of time

• Their reticulopodial net is a highly efficient food gathering apparatus (conveyor-belt movement)

FOODBANCS:Abundances of Foraminifera in the

>300µm size class

• Agglutinated foraminifera are more abundant than metazoa in the macrobenthic size class (>300 µm) in the topmost sediment layer (0-0.5 cm)

• Metazoan organisms are more abundant in the 0.5-1.0 cm layer below

• Organic matter from the spring phytoplankton bloom is most likely be processed to a great extent by foraminifera before metazoan organisms can get to it

It’s not just about quantity!

Food that’s 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 many

• In 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 hormones

• Phytoplankton 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 analysis

• Three of the most abundant species of Foraminifera feed very selectively on certain components of freshly deposited organic matter

• There 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 Palmer

• Time series: development of fatty acid profiles of an abundant calcareous foraminiferal species – Globocassidulina crassa - in January-February

• Feeding 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

So…

Foraminifera have a potentially very important and complex role in areas with a pulsed food input such as the

Antarctic.

Figure 4: MDS plot of replicate samples; = phytodetritus, = Gobocassidulina subglobosa, = Quinqueloculina sp., = Thurammina sp. (Stress = 0.09)

Suhr et al. (2003) MEPS Vol. 262: 153–162