Tag Archives: SAR

Friday Fellow: Bubble Globigerina

by Piter Kehoma Boll

A little more than a year ago I introduced the first foraminifer here, the tepid ammonia. Now it is time to bring the second one, this time a planctonic species that is rather famous and whose scientific name is Globigerina bulloides, or the bubble globigerina as I call it.

Globigerina_bulloides

A live specimen of Globigerina bulloides. Photo extracted from Words in mOcean.

This species can be found throughout the world, but it’s more common in cold subantarctic waters and a little less common in subarctic waters. The most common areas are the North and South Atlantic and the Indian Oceans, but the tropical records are most likely a misidentification of other closely related species.

The bubble globigerina usually lives in the upper 60 m of the water column, at least while reproducing, and feeds on other planktonic organisms, especially microscopic algae. In oder to maximize the ability of their gametes to meet in the vast extension of the ocean, the bubble globigerina synchronizes its sexual cycle with the moon cycle, reproducing during the first week after the new moon. It is, therefore, a kind of biological calendar.

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ResearchBlogging.orgReferences:

Bé, A. W. H.; Tolderlund, D. S. 1972. Distribution and ecology of living planktonic Foraminifera in surface waters of the Atlantic and Indian Oceans. In: Funnell, B. M.; Riedel, R. (Eds.) The Micropaleontology of Oceans, Cambridge University Press, pp. 105–150.

Schiebel, R., Bijma, J., & Hemleben, C. (1997). Population dynamics of the planktic foraminifer Globigerina bulloides from the eastern North Atlantic Deep Sea Research Part I: Oceanographic Research Papers, 44 (9-10), 1701-1713 DOI: 10.1016/S0967-0637(97)00036-8

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Friday Fellow: Northern Plaited Radiolarian

by Piter Kehoma Boll

Some weeks ago I introduced a diatom here and mentioned that, despite the fact that they are a very abundant group, little information on species is available. Today our species is a radiolarian and, just as with the diatoms, they are abundant but little known.

I struggled to find an extant species that also had a good and available photo to share. And the winner was a species known as Cleveiplegma boreale, or Rhizoplegma boreale perhaps. I’m not sure what is the currently accepted name. Anyway, it does not have a common name, but I decided to create one, so let’s call it “northern plaited radiolarian”.

Radiolarians are unicelular organism that have an intricate mineral skeleton that contains a central capsule that typically divides the cell into two portions: an inner one and an outer one. Our fellow today looks like this:

cleveiplegma_boreale

A living specimen of the northern plaited radiolarian. Photo by John Dolan.*

The northern plaited radiolarian has from 6 to 10 spines growing out of it and there is a complex plaited pattern of the skeleton that surrounds them and the inner shell. Measuring anout 20µm in diameter, it is a rather large radiolarian.

Although it is known from fossils along the Quaternary, from at least 10 thousand years before present, the northern plaited radiolarian is still a living species. Currently it is known to occur in the Nordic Seas, around Scandinavia, Iceland and Greenland, in the North Pacific, including the Bering Sea, and in the Southern Ocean, around Antarctica. We can see, therefore, that this species likes cold waters.

Ah, and they feed on diatoms… I guess.

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ResearchBlogging.orgReferences:

Dolven, J., & Bjørklund, K. (2001). An early Holocene peak occurrence and recent distribution of Rhizoplegma boreale (Radiolaria): a biomarker in the Norwegian Sea Marine Micropaleontology, 42 (1-2), 25-44 DOI: 10.1016/S0377-8398(01)00011-1

Dumitrica, P. (2013). Cleveiplegma nov. gen., a new generic name for the radiolarian species Rhizoplegma boreale (Cleve, 1899) Revue de Micropaléontologie, 56 (1), 21-25 DOI: 10.1016/j.revmic.2013.01.001

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Friday Fellow: Giant Kelp

by Piter Kehoma Boll

This week we’ll stay in the sea and meet on of the most impressive algae, the giant kelp, Macrocystis pyrifera. It is called giant for a good reason, since it can grow up to 50 m in length and form real forests in the sea. Being able to grow 60 cm in a single day, it has the fastest linear growth of any organism on Earth.

The giant kelp is a brown algae, so it is not related (at least not closely) to green or red algae, but it is a relative of the tiny diatoms that cover the ocean. It grows in cold waters along the Pacific Coast of the Americas and close to the coast of the countries near Antarctica, such as Chile, Argentina, South Africa, Australia, and New Zealand.

macrocystis_pyrifera

It’s a really beautiful alga, isn’t it? Photo by California Academy of Sciences.*

This amazing organism is composed by a thallus that branches at the base and then continues as a single and very long stalk from which blades develop at regular intervals on only one side. At the base of each blade, there is a gas  bladder that helps the whole organism to stand in a more or less upright position.

The huge kelp forests in the oceans are an important ecosystem and many species depend on them to survive, including other algae. Humans also use the giant kelp either as a direct food source or as a source of dietary supplements, since the alga is rich in many minerals, especially iodine and potassium, as well as several vitamines.

macrocystis_pyrifera2

The kelp forests sustain a huge diversity of lifeforms in the oceans. Photo by Stef Maruch.**

In the last decades, the kelp populations are decreasing rapidly. This is most likely caused by climatic changes, as this alga cannot develop in temperatures above 21°C. The giant kelp is, thus, just one more victim of global warming. And if it goes extinct, a whole ecosystem will be gone with it.

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ResearchBlogging.orgReferences:

Foster, M. (1975). Algal succession in a Macrocystis pyrifera forest Marine Biology, 32 (4), 313-329 DOI: 10.1007/BF00388989

Wikipedia. Macrocystis pyrifera. Available at . Access on January 19, 2007.

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Friday Fellow: Tepid ammonia

by Piter Kehoma Boll

One of the few groups of living being not yet featured in Friday Fellow is Rhizaria, a group of single-celled organisms that includes the famous foraminifers. So today I decided to bring you just that, a foraminifer. And I think a good species to start with is Ammonia tepida, or the “tepid ammonia” as I decided to call it.

A live Ammonia tepida. Credits to Scott Fay.*

A live Ammonia tepida. Credits to Scott Fay.*

The tepid ammonia is found worldwide in brackish waters, or more precisely in the sediments deposited in brackish waters worlwide. It is able to tolerate a wide range of temperatures and degrees of salinity and is considered an ideal species of laboratory studies. As most foraminifers, the tepid ammonia secrets a shell of calcium carbonate, which is deposited on the cell’s surface in the form of a chain of chambers forming a spiral path, thus making it look like a snail shell.

Living in the sediments, the tepid ammonia feeds mainly on algae, but also consumes bacteria. In the laboratory, it demonstrated to have the ability to prey on small animals, such as nematodes, copepods and molluk larvae.

This kid got talent!

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References:

Dupuy, C.; Rossignol, L.; Geslin, E.; Pascal, P.-Y. (2010) Predation of mudflat meio-macrofaunal metazoans by a calcareous foraminifer, Ammonia tepida (Cushman, 1926). The Journal of Foraminiferal Research 40 (4): 305–312.

Munsel, D.; Kramar, U.; Dissard, D.; Nehrke, G.; Berner, Z.; Bijma, J.; Reichart, G.-J.; Neumann, T. (2010) Heavy metal incorporation in foraminiferal calcite: results from multi-element enrichment culture experiments with Ammonia tepida. Biogeosciences 7 (8): 2339–2350.

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