Canadian Association of Palynologists
 

Palynology at the Hole

by
Rob Fensome and Andrew MacRae
Geological Survey of Canada (Atlantic)
Dartmouth, Nova Scotia

The 30th Annual Meeting of the American Association of Stratigraphic Palynolygists (AASP) took place this year (1997) in the idyllic setting of Wood's Hole, Massachusetts. Wood's Hole is the home of the Marine Biological Laboratory (MBL), Wood's Hole Oceanographic Institution (WHOI or "Hoo-ee" as it seems to be called by locals), Alvin the submersible, and the ferry services to the evocative Martha's Vineyard and Nantucket islands. The venue was indeed different from a hotel-orientated setting, more familiar for AASP meetings. Most attendees stayed at the Swope Center of the MBL, which not only provided beds, but meals, "free" booze during the 5 o'clock to 6 o'clock happy hour (hic), and a sumptuous lobster supper (yes, which even we lobster connoisseurs from Nova Scotia enjoyed, though perhaps we may have been mellowed in our lobster assessment capability by the foregoing happy hour).

Not only the accommodation differed from the usual format. The organizers, Sarah Damassa, Ken Piel and Paul Strother, decided to focus the meeting around a particular theme and invite several "key- note" talks relating to that theme. The theme chosen was "Evolution of the Marine Phytoplankton" and the invited talks were on diatoms, dinoflagellates, invertebrates, nannoplankton and Precambrian life. We'll discuss these talks in more detail below. We feel that this experimental format was a resounding success from the scientific point of view: the general quality of the talks was excellent and the interest level was indicated by the high level of animated discussion that arose in the ample scheduled question periods. What may have been a problem was the marketing of the idea: the fact that only 59 people registered, although possibly a sign of the times, may also reflect the feeling of non-phytoplankton oriented palynologists that the meeting would hold no interest for them. If this is the case, it's a shame because it was not the intention of the organizers to exclude other aspects of palynology, and other aspects were certainly well represented among the presentations.

So, more about the juicy invited talks. Andrew Knoll was the first invitee off the mark on Monday morning. He discussed "Life in the Precambrian Oceans". Andy noted that leiospheres, which are presumably the earliest remains of eukaryotes, first appeared about 2400 Ma and that acritarchs showed substantial morphological differentiation by 1300 Ma. This diversity was abruptly curtailed at the onset of the Varinger glacial event, but increased again at the same time as the Ediacaran fauna, only to decline again just before the end of the Precambrian. It is sobering to think that all these events happened before the Cambrian "explosion", which only 50 years ago was heralded as the onset of significant life on Earth. Andy also showed that examination of Precambrian fossils can stimulate the discovery of new living organisms - a new living genus and species was discovered in intertidal encrustations after fossils from analogous Precambrian paleoenvironments had pointed the way.

The Monday afternoon invited paper was on dinoflagellates, co-authored by the two of us and three other Canadians, neontologists Max Taylor and Gary Saunders and paleontologist Graham Williams. We're not sure if there is some significance to the fact that it took only one author each to discuss the other keynote topics, but five of us to discuss dinos! (Shades of "How many Lower Slobovians does it take to screw in a light bulb?") Anyway, we attempted to review the evidence for the course and pattern of dinoflagellate evolution, bringing in considerations from the fossil record, biogeochemical evidence (more below), and the ultrastructure of modern dinos and their molecular phylogenetics (i.e., "RNA studies"). The way all these sources of evidence are coming together is an exciting current development that will be a major theme at next year's DINO6 meeting in Trondheim, Norway.

On Tuesday afternoon Sherwood ("Woody") Wise led off with a relaxed and stimulating discussion of calcareous nannofossils, which of course mainly consist of coccoliths. Woody told us that the group first appeared in the Late Triassic and diversified to such an extent through the Jurassic that the expansion is reflected in the change from "black" to "brown" to "white" Jura in Europe. Through to the Early Creta- ceous, the greatest diversity and abundance was in open ocean environments. In the Late Cretaceous, this focus shifted to the continental shelves and interior seaways, the result being the great chalk belts of North America and Europe that gave the Cretaceous its name. Woody noted that, unlike dinoflagellates, nannoplankton underwent a sudden and drastic extinction at the K/T boundary, rebounded to some extent in the Paleogene, but then generally declined in the Neogene. Many aspects of this pattern - appearance in Late Triassic, diversification in the Jurassic, peaks in mid to late Cretaceous and decline in the Neogene - are intriguingly familiar to dinoflagellate workers.

John Barron is perhaps best known to a general audience for his papers on paleoclimatology, but his roots are in the diatom business, and it was as a specialist in that siliceous group of microfossils that John addressed us on Wednesday morning. He told us that the earliest definitive diatoms are from the Early Jurassic, but the earliest forms are from the Early Cretaceous. Diatoms may have evolved earlier than these records suggest, but the vulnerability of the opaline silica diatom frustules to alkaline pore waters and temperatures in excess of 50°C makes their preservation in older rocks a risky business. John suggested that continued study of diatoms in protective concretions should in the future contribute significantly to our understanding of early diatoms. There was an "explosive" (John's word) radiation of diatoms in the Late Cretaceous, but no major extinction event at the K/T boundary. He suggested that the presence of resting spores (or "cysts") in the life cycle allowed diatoms to survive that environ- mental crisis - a possibility that we might also invoke for dinoflagellates. In the Cenozoic, diatoms had their ups and downs that John related to climate, but, unlike dinos and nannos, no general decline in the Neogene.

With no disrespect intended to Andy, Woody and John, the star of the invited speakers was Richard Bambach, who delivered an exceptional presentation on the "Evolution of the Marine Ecosystem" after dinner on Tuesday. Richard reviewed the changes in ecosystem structure through time, emphasizing the metazoan invertebrates. The first 2.5 billion years of the history of life was a story involving only producers and decomposers - no consumers. Consumers first appeared in the Vendian, but their limited presence even then allowed the sessile Ediacaran fauna to survive. With the Cambrian radiation and consequent increase in consumers, Ediacaran type faunas could no longer survive. Richard pointed out that, although there is perhaps not a significant difference between Paleozoic and later diversities of marine animals, Paleozoic forms were mosty gristle and skin - if you look inside a brachiopod, "there's no one home". However, organisms that dominated the Mesozoic and Cenozoic seas were fleshy, more massive, and included more carnivores, signifying a change in energy transfer and other ecological factors. Why a talk on such macrofossils at a meeting focusing on phytoplankton? Well, phytoplankton are "fish food" of course, and a full understanding of the ecological and evolutionary patterns among consumers can only be gained by a consideration of patterns at the lower end of the food chain. Richard posed the critical questions: 1) what changes in the primary ecosystem influence the consumer system; and 2) what are the feedbacks from consumers that influence primary producers?

Of the other talks, space limits the number that we can mention specifically, and we have to be honest and say that, even between the two of us, we didn't attend every talk - collaborative discussions (perhaps the most valuable aspect of meetings) distracting our attention for some of the time. Apart from the invited presentations, the highlight for both of us was Nina Talyzina's talk (co-authored by Michael Moldowan and the late Gonzalo Vidal) on the distribution of dinosterane geochemical biomarkers in Early Cambrian acritarchs. Using a novel application of a technique from cell biology, Nina was able to extract and concentrate fractions from standard palynological preparations based on their different fluorescence characteristics. The resulting fractions consisted of leiospheres and tasmanitids, neither of which yielded dinosteranes, and acanthomorph acritarchs, which did. These results have obvious implications for the affinities of some acanthomorph acritarchs, and are consistent with molecular phylogenetic evidence, which suggests that the dinoflagellate lineage evolved in the Late Precambrian. Nina's work is intriguing, innovative, thoughtful and clearly carefully carried out. Questions remain however: where does the dinosterane come from - one wouldn't expect it to be associated within the "sporopollenin" walls in the living organisms; are we sure that the closest living relatives of dinoflagellates (apicomplexans and ciliates) lack dinosteranes; and are the results repeatable using confirmed dinos and prasinophytes of the later fossil record?

Paul Strother reminded us that that bane of a group, the "boring" leiospheres, are polyphyletic and can be marine, and, perhaps surprisingly, non-marine as far back as the Cambrian. Thomas Servais, in a paper co-authored with Stuart Molyneux, expressed scepticism about whether "lineages" of (especially Ordovician) acritarchs can be considered truly evolutionary in nature.

John Beck provided a summary of his work on the Silurian Arisaig Group of Nova Scotia, a spectacular succession that has received surprisingly limited palynological attention in the past. In addition to a diverse acritarch flora (130 species), an impressive non-marine spore and cryptospore flora occurs starting in the Llandovery, and transgressive-regressive trends are evident in the distribution of major palynomorph groups and palynofacies.

Moving up section into the Mesozoic and Cenozoic, Raffaella Bucephalo Palliani and Jim Riding presented a very interesting story of Early Jurassic dinoflagellate migrations and paleoecology. Tipped off by the fact that certain taxa have different ranges in the Boreal and Tethyan Realms, Raffaella and Jim revealed evidence for two migrational events, one at the early/late Pliensbachian boundary, the other in the mid Toarcian.

Calcareous dinoflagellates are a group that have had a blossoming of attention lately, with several recent major monographs (most written, oddly, by authors with surnames starting with a "K"). Calcareous dinos with visible tabulation all show a stable peridiniacean pattern, and have a range of characteristic "apical" archeopyles, the likes of which have only very exceptionally been found among organic-walled forms. However, Sarah Damassa presented the final talk of the meeting on a group of organic-walled cysts that clearly show the archeopyle styles so characteristic of calcareous cysts. Sarah's interpretation was that these new forms do not appear to represent linings of calcareous cysts from which the inorganic component has been dissolved, but separate, albeit related, forms. Sarah's material is from the Eocene to Miocene of several localities in the North Atlantic and its borderlands.

The history of dinoflagellate studies has had its share of enduring "dynamic duos" - its own versions of Batman and Robin. There was Cookson and Eisenack in the 1950's and 1960's and Lentin and Williams in the 1970's through 1990's. The "Batman and Robin duo" (though we're not revealing who we think of as Batman and who as Robin) forever associated with Wood's Hole is that of Wall and Dale. David Wall and Barrie Dale carried out seminal work on dinoflagellate cyst-theca relationships at the Marine Biological Laboratory primarily in the mid to late 1960's. The dynamic duo was reunited at this meeting, and both were active participants. Barrie, indeed, treated us to a talk, co-authored with his wife, Amy Dale, on environmental controls on the evolution of cyst-forming dinoflagellates. Barrie and Amy took the 20 most common modern cyst types and assigned tham to four environmental categories: warmer coastal, colder coastal, cosmopolitan and oceanic. Barrie pointed out that the geological record of these categories shows some notable trends. The warmer water and oceanic types, as well as most of the cosmopolitan types have longer histories (back to the Eocene in many cases) than the colder water types (only back to the late Miocene at most). Thus the warmer water and oceanic forms have been able to "track" their environments during times of climate change and the cosmopolitan forms have been able to tolerate those same changes. In contrast, the colder water species have more recently evolved in response to the onset of new cold water environments.

Gordon Wood and co-authors presented an integrated palynological and organic geochemical study of an Eocene source rock in Pakistan. Through an interval of less than 2 m, there were large vertical variations in organic facies and the proportions of reworked Jurassic palynomorphs and in situ palynoflora. Particularly unusual was the occurrence of organic remnants of possible diatoms (whose presence is consistent with the geochemical biomarkers) and a nearly monospecific assemblage of an undescribed dinoflagellate. The latter assemblage also yielded an unusual, unidentified dinosterane-like molecule that can perhaps serve as an indicator of similar environments.

There were several papers dealing with purely Quaternary topics. CAP Secretary/Treasurer, Francine McCarthy, in a paper co-authored with Steve Blasco, David Dubas and Kevin Gostlin, asked "Where have all the sediments gone?" We found out that the title didn't refer to some Great Rock Robbery perpetrated at geological departments throughout the world, but an apparent gap in the sedimentary record of Georgian Bay since the mid Holocene, its temporal extent confirmed by palynology. The authors attributed the gap - actually a condensed succession - to a dramatic decrease in sediment influx due to cessation of transgression. Francine alluded to the important environmental inplications of this interpretation.

The only paper of the technical session (in contrast to the invited papers) that was not based on palynomorphs was presented by Melissa McQuoid, from Victoria, B.C. Her paper, co-authored with Louis Hobson, involved a study of diatoms and silicoflagellates as Holocene climatic indicators in Saanich Inlet, B.C. The inlet has laminated sediments that can be sampled at annual and subannual resolution. Short cores have revealed a record over the last 100 years, and longer timescales can be examined from cores taken on the JOIDES Resolution's visit to Saanich Inlet as ODP Leg 169S (see CAP Newsletter 19(2):16-18, 1996, and CAP Newsletter 20(1):8-10, 1997).

John Wrenn presented a paper with several coauthors on the application of palynology and other microfossil methods (phytoliths and diatoms) to high-resolution dating in Holocene sediments in the Mississippi Delta area. By a combination of plant introduction records and other historical events a very precise chronology was established for the period AD 1750 to 1900, an interval otherwise undatable using radiometric techniques. Particularly interesting was the use of characteristic carbon spherules in palynological preparations to recognize the onset of the use of different types of fuel, and the use of Vigna luteola (cow pea) pollen as a proxy for sugarcane production.

A common topic of discussion during this meeting was the application of computers to palynology. This subject received specific attention in a Tuesday morning session entitled "Palynology and the Internet". Owen Davis discussed in general terms about the protocols in use on the Internet and their utility for palynology. Clearly there is great potential for the easy storage and distribution of large amounts of palynologically related text and image data on the World Wide Web. Subsequent speakers discussed several implementations of palynological data distribution and analytical tools. For example, there was free software from the International Quaternary Association (Louis Maher), paleobotanical information (Mike Boulter), and the Global Pollen Database (Eric Grimm and John Keltner). In two later talks during the last day of the conference, Robert Williams and Eric Monteil introduced the audience to Dinium-Alpha, program for storing dinoflagellate images and morphologic and stratigraphic data. Robert also gave an impromptu demonstration of digital image processing as it applies to palynomorphs. With image capture hardware becoming relatively inexpensive and yielding much better results than a few years ago, a suprising amount of work can now be done "filmless", offering advantages in cost and versatility.

Outside of the formal talks, there was a demonstration by Ken Piel of a new graphical interface to the PALYNODATA database of pre-Quaternary palynological information. This vast dataset is now much more accessible than in earlier implementations. Another commercial demonstration was for equipment for microwave-enhanced digestion of palynological samples (as described in Palynology, Vol. 18, p. 23).

Awards were given out at the AASP Business Luncheon at - where else - the Swope Center on Thursday. Robert Booth, a student of Fred Rich at Georgia Southern University, won the best student paper award for his presentation "Palynology and Depositional History of Late Pleistocene and Holocene Coastal Sediments from St. Catherines Island, Georgia, U.S.A." (He also won the award for the longest title - just kidding.) Merrell Miller of AMOCO, Houston won the best poster award for his poster "Palynological Characterization of a Silurian Transgressive Event". And last but not least, our own former CAP President from Simon Fraser University, Rolf Mathewes, was inducted as the new President of the American Association of Stratigraphic Palynologists. Congratulations Rolf - doubly so if you're still with us at the end of this wordy review!

As far as meetings go, this was one of the best organized and most stimulating that we have attended, and Ken, Paul and Sarah are to be commended for arranging and staging such a successful meeting.
 


This article first appeared in CAP Newsletter 20(2):7-12, 1997.
 


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