Spores and pollen in the marine realm

14 SPORES AND POLLEN IN THE MARINE REALM LINDA HEUSSER

INTRODUCTION

Pollen

In contrast to the other microfossils discussed in this book, pollen and spores of plants are an allochthonous marine micropaleontologic group. That is, unlike foraminiferans or radiolarians, pollen and spores are not marine organisms, but are the products of continental vegetation, and might best be considered as a biogenous component of fine-grained (5-150 jum) detrital or terrigenous marine sediment. Interest in marine palynology, the study of pollen and spores in present-day oceans and ocean sediments, has grown concomitantly with the mid-twentieth century development of oceanography. Although the stratigraphic and ecologic potential of terrestrial microfossils in marine sediments was recognized when pollen and spores were first described from marine cores, the full potential has yet to be exploited due to lack of meaningful data. MuUer's (1959) classic work on the Orinoco Delta, South America, was the first comprehensive study of the distribution of marine palynomorphs in space and time. Subsequent studies of a similar nature have been conducted on the continental shelf and in relatively restricted areas such as the Gulf of California and the Sea of Okhotsk (Koreneva, 1957; Cross and others, 1966). When Stanley reviewed the field of marine palynology in 1969, less than fifty papers had been published by about half as many authors, most of which dealt with pollen in surface sediment or in cores with sediment of Quaternary age.

Pollen grains are the male reproductive bodies (microgametophytes) in seed plants (Fig. 1). They originate on the anthers of flowering plants, or angiosperms (like oaks, grass, roses) and in the microsporangia of gymnosperms (pines, firs, spruces). After pollination (transfer of the pollen grains to the female reproductive part) and fertilization (fusion of the sperm or male gamete with the egg or female gamete), the embryo develops within the ovule which becomes a seed. Coniferous pollen types were first described from the Pennsylvanian and angiosperm pollen from the early Cretaceous.

Fig. 1. A tetrad pollen type, Drimys winteri, showing three of the four components, x 1800.

327

328

SPORES AND POLLEN IN THE MARINE REALM

Spores Spores produced by "lower plants", such groups as algae, fungi, mosses, and ferns, are some of the earliest preserved remains of plants (Fig. 2). The Silurian marks the appearance of the first accepted spores with triradiate sutures. Spore production in primitive vascular plants, such as the club moss, may be homosporous, that is, a single type of spore is formed; or heterosporous. Heterosporous plants, those that produce male microspores and female megaspores, are known since the late Devonian. (In a strict sense pollen grains are microspores and are analogous to the microspores of ferns.) In homosporous plants the spore germinates and develops into either bisexual gametophytes or into two plants one of which produces male gametophytes and one female gametophytes.

reading" for a more extensive account of pollen and spore morphology and taxonomy. We will touch upon these aspects only briefly. Pollen grains (and spores) are distinguished by the aspects of morphology — size, shape, apertures, surface sculpture — and wall structure. Size The size of the majority of pollen grains is between 20 and 80 //m, with rare forms less than 10 jum to more than 200 jum. Approximate size is relatively constant and useful in identification; however, it should be noted that size variations are caused by a number of factors, including preparatory technique. For example, mounting in glycerine gelatin tends to cause swelling of the pollen grains; the same grains embedded in silicone oil are about 30% smaller. Shape A wide variety of radially symmetrical shapes exist, of which variations of the rotational ellipsoid are more common. The relation between the polar and equatorial dimensions forms the basis for definition of commonly used shape classes, some of which are illustrated in Fig. 3. Variations of the ellipsoid form are frequently encountered. Bilaterally symmetrical convex pollen grains are produced principally by two groups, the monocotyledons (lilies) and the gymnosperms. The latter produce vesiculate grains, those with sacci (bladders or wings) (Fig. 3F).

Fig. 2. A monad X 1500.

apore,

Lycopodium

gayanum.

CHARACTERISTICS

Distinguishing criteria for pollen The reader should consult one or more of the texts listed in "Suggestions for further

Apertures The number and t5^e of apertures (openings or thinning of part of the exine) form the primary basis for pollen differentiation. Generally, isodiametric apertures are called pores, and elongate or furrow-Hke apertures are called colpi (Fig. 4). Pollen grains may have no apertures (inaperturate), single apertures (monoporate or monocolpate), multiple pores (diporate, triporate, stephanoporate, or periporate), multiple colpi (dicolpate, tricolpate, stephanocolpate, heterocolpate, or syncolpate), or multiple pores and colpi (dicolporate,tricolporate, stephanocolporate, pericolporate).

329

L. HEUSSER

Proximal pole

Polariaxis

Cap

Dorsal root of sac

Ventral root of sac

Fig. 3. Some common shapes of pollen grains. A. Prolate. B. Subspheroidal. C. Oblate. D. Pentagonal. E. Irregular. F. Vesiculate. G. Descriptive t e r m s . (All figures approximately x 330, except D: x 890.)

Sculpture Perhaps of greatest diagnostic value in the identification of pollen grains are surface sculpture and wall structures. Some twelve kinds of sculpture are recognized: these include tj^es that are smooth, pitted, grooved.

or ones that exhibit more or less isodiametric or elongate elements (see Fig. 4). Wall structure Sculptural elements are developed in the outer structural layer of the pollen grain, the exine, which is frequently divided into an inner homogeneous layer, the endexine, and an outer layer, the ektexine (Fig. 5). The exine is composed of a complex of minerals and organic compounds which include sporopoUenin, a "natural plastic" which is highly resistant to degradation. The intine or interior wall of the pollen grain which encloses the protoplasm or living nucleus is largely composed of cellulose and other substances which are readily destroyed and thus are rarely fossilized.

* Tectum

-< Fig. 4. Scanning micrographs showing some a p e r t u r a l types and sculpture on pollen grains. A. Diporate, microechinate grain of Embothrium coccinineum. X 1400. B. Tricolporate, echinate grain of Corynahutilon vitifo/ium. x 750. C. Triporate, foveolateechinate grain of Cereus chiloensis, x 750. D. Triporate, echinate heterobrochate grain of Lomatia ferruginea. x 1500.

Columella

^

;

> Ektexine

Foot

layer J Endexine

Fig. 5. Details of the pollen wall structure.

330

SPORES AND POLLEN IN THE MARINE REALM

Spore characteristics Spores are spheroidal, tetrahedral, or elongate (generally biconvex or planoconvex) and when mature occur both singly and in tetrads. The size of late Cenozoic spores is comparable to that of pollen; older spores may be as large as 2 mm. Surface sutures, scars or laesurae, are usually single (monolete), or triradiate (trilete), although they may be absent (alete) (Fig. 6). The spore wall, hke that of the pollen grain, is composed of intine and exine. An outer layer or envelope called the perine appears in certain spores (Fig. 7). Many spores are decorated with sculptural elements in the same manner as pollen grains. Variations in sculpture, as well as structure, are more prevalent in trilete spore groups than in monolete groups. Envelopes enclosing spores to varying degrees are characteristic of many Paleozoic groups. Crassitudes (equatorial envelopes), sacci (wings), extensions of the tectum (fused and unfused) are commonly developed in Paleozoic and Mesozoic spores.

Fig. 6. Major spore types. A. Monolete. B. Trilete. x500.

tive (x 950—1500 magnification) and an authenticated reference collection of pollen and spores from the area being studied with which comparisons can be made. Preparation techniques designed to extract and concentrate the pollen by chemical or physical methods vary according to the matrix and personal preference of the palynologist. Many extraction techniques are covered by Gray (1965) in the Handbook of Paleontological Techniques. Obviously sampling size and intervals will depend on the purpose of the study, the type of sediment, and the rate of sedimentation. Generally significant numbers of palynomorphs can be extracted from 3 to 5 cm^ of organic terrigenous lutites. Up to 10-20 cm^ of less organic terrigenous sediment may have to be processed to obtain counts of more than 100 pollen grains. Traverse and Ginsburg (1966), for example, processed 25 g of calcareous sands from the Great Bahama Bank. As plants are sensitive indicators of terrestrial ecologic change, it is desirable to sample at the closest intervals possible. In some areas, such as Santa Barbara Basin and Saanich Inlet, Vancouver, British Columbia, our samples cover about 10-year intervals and the presence of varved sediments may permit the sampling of yearly intervals. In sampling marine sediments for pollen analysis, it is extremely important to obtain uncontaminated material. Many marine samples and cores are stored at temperatures which permit the growth of fungi on the outer surface of the sediment. External surfaces of cores may also be contaminated by poUen from the air. By avoiding material from the external surfaces, the possibility of contamination can be reduced.

^J^ ^ ^ i ^ ^ 50/im

Fig. 7. Loosely folded outer layer (prine) on a monolete spore, Athyrium alpestre.

Methods Identification of pollen and spores requires a high quahty compound binocular microscope equipped with an oil immersion objec-

FACTORS AFFECTING THE NATURE OF POLLEN IN THE MARINE ENVIRONMENT

The nature of the relationship between pollen in marine sediment and the source of the pollen, the species of the plant communities, is complex and can be envisioned as a function of a number of interrelated processes (ecologic, penecontemporaneous, and diagenetic).

331

L. HEUSSER Cascade mts. 4000 m

O l y m p i c mts,

Northeast Pacific

Olympic Peninsula

Puget Trough pme

L hemlock:::^

I I I I I

spruce

scale 0

Mt. Rainier

Cascades

I I

^

fir

^

Douglas

/I

fir

V

alder

A

I I

herbs V/V

50«/o

Fig. 8. Comparison of major pollen groups in surface sediments from the northeast Pacific and from a transect across Washington. Data from the core tops are the author's. Data from western Washington were derived from Florer (1972), Hansen (1947, 1949), and Heusser (1969, 1973). The cartoon illustrates the dominant vegetation of different elevations of the western Olympic Peninsula, Puget Trough, Mt. Rainier and the Cascades, and the Columbia Basin (Franklin and Dyrness, 1969).

Ecologic processes

P e n e c o n t e m p o r a n e o u s processes

Among the ecologic processes which delimit the plant communities from which pollen and spores are derived are climate, topography, edaphic or local factors such as soil and ground water, fire, and man. Plant communities are characterized by distinctive pollen assemblages. Although the relationship between the abundance of plants in the ecotone and the abundance of pollen is not always a simple one-to-one ratio*, in many geographic regions the pollen assemblages can be used to distinguish the broad features of the vegetation. For example, in eastern North America, Davis and Webb (1975) show close geographical correlation between contemporaneous pollen rain and the distribution of modern vegetation. The correlation between modern pollen rain and plant assemblages of western Washington is illustrated in Fig. 8.

Diffusion, deposition, and destruction, the major penecontemporaneous processes act selectively and in essence screen the pollen and spore assemblage. Initial pollen dispersal from the plant to the surrounding environment is primarily anemophilous (by wind), zoogamous (animal) and hydrophilous (water); initial diffusion is comparatively unimpotant and dispersal distance short. Estimates vary from 10 to 150 km as a "natural" limit of primary diffusion, although long distance wind transport of up to 1500 km of small amounts of pollen has been reported. Some pollen may be wind-transported from coastal regions to the marine borderland. Estimates of coastal pollen rain range from 10^ to 10^ grains/cm^ per year (Dyakowska, 1948). The nature and concentration of aeolian pollen would obviously depend on atmospheric circulation and on the aerodynamic properties of the pollen grains. Pollen and spore content of the atmosphere beyond the continental margins is low, on the order of 10-10^, and it would appear that aeolian transport would be

*Pollen produced by individual species in a plant community ranges from one mLlhon grains/flower in pine to ten grains/flower in beech (Erdtman, 1969). Generally less poUen appears to be produced in restrictive environments, such as in tundra biomes, than in more temperature environments.

SPORES AND POLLEN IN THE MARINE REALM

332

145°W

140*

135'

130"

125°

120"

Fig. 9. Map showing distribution of pollen concentration (grains/cm^ in marine sediments) off NE Pacific coast of the United States. Contours are in grains x lOVcm'^.

relatively unimportant in the dispersal of pollen to the deep sea. In some areas, however, as off western Equatorial Africa and in the Mediterranean, windblown pollen may form a significant proportion of marine palynomorphs. Fluvial transport is probably the major means of pollen dispersal to the marine environment. Although long-term data are lacking, isolated observations on the amount of pollen in rivers and estuaries range up to 8000 grains/hter. In an extended study of a small catchment basin in England (Peck, 1973), comparison of the aerial and fluvial components of the pollen supply indicated that greater than 90% of the new pollen was derived from stream transport. Concentrations of pollen on the continental margins are higher adjacent to stream influx and lower off areas lacking permanent drainage. PoUen concentration in the northeast Pacific Ocean (Fig. 9) clearly reflects the influence of fluvial input of pollen. Contours of maximum amounts of pollen coincide with the distribution of the Colimabia River plume, the major source of suspended sediment in the northeast Pacific. Secondary maxima occur off the outlet of the Sacramento and San Joaquin Rivers in California.

When pollen grains enter the water and are wetted, it appears that they are transported and deposited in the same manner as suspended particles of the size of fine silt and clay. Little data are available concerning the hydrodynamics of pollen grains, however Hopkins' (1950) observations suggest that hydrodynamic properties of pollen and spores may be species specific. Analysis of suspended and surface sediments of rivers and estuaries indicate that fluvial pollen assemblages are similar to the regional vegetation of the entire drainage basin rather than to local environments. According to McAndrews and Power (1973) pollen in the surface sediments of Lake Ontario is generally uniform and reflects the deciduous and coniferous vegetation of the various streams which drain into the lake. Similar results were found by Groot (1966) in the Delaware River and by Thompson (1972) in the Raritan River in New Jersey, where the pollen content of the river, the estuary (Raritan Bay) and the atmosphere show a 67% similarity. In the ocean, as in streams, pollen is believed to function as suspended, terrigenous particles. Overall, the amount of pollen in modern marine sediments is decreased seaward due to progressive lateral and vertical mixing with marine water of lower sedimentary particle concentration; however, the concentration of pollen grains in marine sediments is not necessarily in a simple linear relation to distance from land or to increased depth of water. In the northeast Pacific Ocean, poUen concentration is polymodal, being lower on the shelf, higher on the slope and rise, and decreases to minimal values in the basins. The quantity of poUen seems to be positively related to the distribution of lutites which bypass the outer shelf (Harlett and Kulm, 1973) and are transported to the slope by subsurface currents and particle setthng from overlying waters (Baker, 1973). The general parallehsm of the pollen concentration contours with marine isocHnes in the northeast Pacific suggests that the pattern of poUen concentration is partly a function of distribution by surface currents. The complex distribution of pollen in shelf sediments of the Orinoco Delta was related by Muller (1959) to the influence of surface currents.

333

L. HEUSSER

MS^W

140»

135»

125»

120»

Fig. 10. Map showing distribution of relative abundance (percent of the pollen sum) of Pinus. Geographic extent of Pinus species from which pollen in marine sediment may be derived is indicated by shading.

The selective nature of marine transport has frequently been inferred from the decreased diversity of marine pollen assemblages compared to continental pollen assemblages

and from the prominence of pine pollen in marine sediments. In core tops from the continental margin of the northwest Atlantic, about 90% of the pollen is pine, whereas on the adjacent coast the relative frequency of pine pollen ranges from 30 to 75% (Davis and Webb, 1975). At least 30% of all poUen in over 100 core tops from the northeast Pacific Ocean is pine (Fig. 10), both in samples adjacent to areas where pine is prolific and where pine trees and pollen are absent, such as the northern and southern extremities of the coast. This suggests transport by surface currents, the northwest flowing Alaska gyre, and the south flowing California current. Similar observations on the importance of surface currents on the distribution of pine pollen were made by Traverse and Ginsburg (1966) on the Great Bahama Bank. Even more striking is the uniform increase of pine pollen seaward, which apparently reflects the relative hydrodynamic efficiency of pine, although some differential resistance to destruction may also be a factor. The selective effects of marine transport on pinaceous poUen have been described by Cross and others (1966); Koreneva (1964) in a reconaissance study of the western Pacific Ocean, and by LublinerMianowska in the Bay of Gdansk, Poland (1962). Differential destruction of pollen and spores is not confined to the marine environment but is undoubtedly a selective factor from the time pollen grains are produced.

TABLE I Comparative ranking of some major pollen types in relation to corrosion and oxidation susceptibility, sporopollenin content, and preservation ability (based on Havinga, 1964; and Sangster and Dale, 1964) Pollen type

Corrosion susceptibility

Oxidation susceptibility

SporopoUenin content

Preservation ability

Conifers (pines, spruce, fir, etc.)

Ic)W

Ic w

h igh

hi gh

high

high

low

low

Spores (lycopods, polypods) Alder, birch, linden, hazel Oak, maple willow, poplar

334

SPORES AND POLLEN IN THE MARINE REALM

organic carbon in marine sediments, undoubtedly also affect the abundance of pollen and spores which are susceptible to degradation by oxidizing agents. Relatively high pollen concentrations and maximum organic concentrations appear related to minimal dissolved oxygen concentration in surficial marine sediments on the continental margin off Oregon and Washington. The unusually high number of pollen grains per gram of sediment found in the Black Sea by Traverse (1974) may be due, at least in part, to the euxinic character of the sediment. Pollen grains are apparently absent in ancient carbonate environments. Although this may be due to the adverse effect of alkalinity on pollen, as has been suggested, it may also be a function of oxidation and/or sedimentation. In the present carbonate sediments of the Bahamas, pollen is fairly abundant (greater than 100 grains/g) and maximum abundance is associ-

Observations on chemical destruction of pollen and spores in terrestrial environments, such as lakes and bogs, and in the laboratory are summarized in Table I. Bacterial and fungal activity also causes differential destruction of palynomorphs. Different layers of the spore are selectively attacked by microbial activity. The susceptibility of pollen to chemical and microbial degradation may be related to differences in the chemical and mineral composition of the exine, to differences in the chemical structure of the sporopoUenin, and/or to difference in the relationship between the sporopoUenin and the mass of pollen.

Diagenesis Oxidation and bioturbation, diagenetic processes which affect the distribution of

TABLE II Stratigraphic distribution of some major spore and pollen groups (Figs. 1, 4: X 400; 2,3,8: X 325; 5, 6, 7, 9 : X 450). Spores

Pollen

Quaternary

^,—^ Ui


Pliocene

a

CO

A

Miocene

"—' o a

•4->

Oligocene

1

1 O

1

-«->

a;

Paleocene Cretaceous Jurassic Triassic Permian \

Devonian Silurian

^ 0 1

a

Eocene

Carboniferous

0) <<-*

L

:

•4-»

0 a

>>

o au

.M

0

a, 'o

TJ

a 11 -^ •4-i

1

335

L. HEUSSER

ated with fine-grained sediments (Traverse and Ginsburg, 1966). During diagenesis pollen grains may be filled with opaque minerals, such as pyrite or manganese, or with oil. Over time the sporopoUenin undergoes colorimetric evolution which can be detected through fluorescence or by reflective techniques. Pollen and spores stained with Safranin-0 show a gradation in stain acceptance which has been correlated with time by Stanley (1966b). Older grains, Paleozoic or Mesozoic in age, do not readily accept the stain and appear yellow or brown; Pleistocene grains accept stain and appear much like Recent pollen and spores. This coloric differentiation has been used by some palynologists to separate contemporaneous and reworked palynomorphs.

Generally marine pollen assemblages appear to be an amalgam of coastal and regional vegetation, the extent of the region depending on the area of permanent drainage. Muller (1959) found a few grains of alder pollen from the Andes in sediments of the Orinoco Delta, and pollen in the eastern Mediterranean is apparently derived from coastal vegetation and from the Nile River, according to Rossignol-Strick (1973). The relative absence of representatives of the Compositae in marine sediments off the mouth of the Columbia River suggests that the pollen of these sagebrush herbs which cover vast areas of interior Oregon and Washington does not reach tributaries of the Columbia River. The lack of permanent drainage in arid northwest Africa has also been cited as the reason for the depauperate pollen content offshore (Koreneva, 1971).

DISTRIBUTION OF POLLEN AND SPORES IN THE MARINE ENVIRONMENT

Horizontal distribution

Vertical distribution

Despite the complex nature of the processes affecting pollen and spores from the time they leave the plant until they are collected from the sediment, marine pollen assemblages do appear to reflect the vegetation from which they are derived. Comparison of the relative frequency of marine pollen in the northeast Pacific Ocean with the distribution of vegetation on the adjacent Pacific U.S. coast reveals a fairly good correlation of the dominant taxa. For example, western hemlock (Tsuga heterophylla), a prominent member of the temperate conifer forest, reaches optimal development in western Washington and coastal British Columbia, off which maximum percentages of western hemlock are found (Fig. IIA). Spruce (Picea sitchensis) becomes more important in southeastern Alaska, where high relative frequencies of marine spruce pollen occur (Fig. IIB). In California, Sequoia becomes a significant member of the temperate conifer forest and distribution of Sequoia on the continental margin is restricted to coastal California, as is oak (Quercus species) which although more widespread is relatively insignificant in the vegetation and pollen rain north of California (Fig. l i e and D).

The stratigraphic ranges of some major pollen groups are indicated in Table II. Published studies of pre-Quaternary palynomorphs in cores from the present oceans are rare. Organic lutites from several cores in the Bahama Abyssal Plain which contained a rich Cretaceous pollen assemblage were described by Habib (1968), who also identified Cretaceous spores in cores from the North Atlantic off West Africa and north of Surinam, South America. Williams and Brideaux (1972) used distinctive Tertiary pollen assemblages to zone and correlate cores from the Grand Banks, Newfoundland. Pollen and spores of Tertiary age have also been recorded from the shelf off New Zealand, the Aleutian Abyssal Plain, the Black Sea, and the Gulf of Mexico. Spores and pollen in Mesozoic and Tertiary marine sediments have been used primarily to determine the age of the poUiniferous intervals. In the Gippsland Basin of southeastern Australia, late Cretaceous, Paleocene, and Eocene biostratigraphic zones based on spores and pollen were used by Stover and Evans (1973) and Stover and Partridge (1973) to correlate more than 40 offshore wells on the continental shelf. The zonation, an essentially

336

SPORES AND POLLEN IN THE MARINE REALM

50»

45'*

40°

SS-N

35- N

B 145°W

140°

135°

130°

125°

120°

MS'W

140°

135°

130°

125°

120°

J W ^

m

55°

50°

•

-

•• • • •

45°

-

40°

-

35° N

-

I

VYL

•

••• • ••

\

•Wk\ t'/'K—i-""^ • / 10 . \ \ 1/

"^^ W^

•

c 1

1

1

145'W

140°

135°

1

130°

1

125°

\

1

120°

145''W

140

Fig. 11. Maps showing distribution of the relative abundance (percent of the total pollen sum) of Tsuga heterophylla (A), Picea (B), Sequoia (C) and Quercus (D). Geographic extent of T. heterophylla, Picea, Sequoia and Quercus species from which pollen in marine sediments may be derived is indicated by shading.

337

L. HEUSSER PI -RPF-

depth l l

o

m.

I

l-l

I

I

I

9420 ±110 8930 i 150 93001180 h 13.340±500 14.950+240 15.600i240 5X10^ SCALE

SCALE

A. -RPF g.5 in O •

«^ a i
1

i

1

1 ^ 1P— ^

[ASHI

f

1

^

1

t y

[

1

1 f—

SCALE

L

12 3 1 12 3 1 VALUES X 10^ GM-i

6 8 10

Fig. 12. A. Relative pollen frequency (RPF) and pollen influx (PI) diagrams of principal taxa in core HV-67 from the Hoh River Valley, western Olympic Peninsula. B. Relative pollen frequency (RPF) and absolute frquency (APF) diagrams of principal taxa in core 63-013 from the continental slope, northeast Pacific Ocean. (From Heuser and Florer, 1973.)

338 continuous, gradually changing sequence of pollen assemblages, was based on the changes of about 150 species and on the internal consistency of the palynomorph assemblages in each zone. Correlation of offshore wells with wells drilled in coals, interbedded sandstones, clays, and volcanics onshore was based on palynomorph stratigraphy. Pollen analyses from a site drilled in the Ross Sea, Antarctica, suggest that southern beech forests similar to that presently growing in cool temperate South America and New Zealand persisted in the area through the early phases of glaciation in the late Ohgocene (Kemp and Barrett, 1975). The Antarctic pollen assemblage is not unlike that from the Ninety-East Ridge in the Indian Ocean which is interpreted as reflecting flourishing island floras which were colonized by long distance dispersal mechanisms (Kemp and Harris, 1975). Pre-Quaternary and Quaternary spores and pollen have been used as biostratigraphic tools. Quaternary palynomorphs can also be used as paleoclimatologic tools. Our initial studies of chronologically controlled cores from the northwest Atlantic and northeast Pacific suggest that marine pollen assemblages, at least for the past 70,000 years, are correlative with terrestrial pollen assemblages in the region from which the pollen is derived. Comparison of the pollen assemblages in a bog from western Washington (Fig. 12A) with those from a core on the continental slope offshore (Fig. 12B) shows the same sequence of pollen assemblage zones. The late glacial vegetation of the western Olympic Peninsula (Fig. 12A) is composed primarily of grass (Gramineae) and sedge (Cyperaceae), zone L. Minor amounts of pine and herbs are present, and pollen influx (pollen grains/cm^ per year) is low (less than 1000 grains/cm^ per year). Arboreal succession during climatic amelioration is reflected in the pollen diagrams by the successive peaks in the profiles of pine, spruce, alder, and hemlock. The postglacial rise in pollen influx (to 5000 grains/cm^ per year) is interpreted as reflecting increased pollen production during mild interglacial cHmate. The concentration (pollen grains/g) of pollen in late glacial marine sediments is also

SPORES AND POLLEN IN THE MARINE REALM

low, less than 1000 grains/g. Grass and sedge are relatively more abundant in the lower part of the core (zone L) and successive peaks occur in the profiles of pine, spruce, alder, and hemlock, as in the core from continental Washington. An abrupt increase in the density of pollen ca. 10,000 years B.P. reflects the rise in continental pollen influx. The profile of pine in zones P-2 and P-3 of the marine core differs from that of the same zones in the terrestrial core. In the Hoh River Valley pine decreases as the spruce-hemlock forest develops, whereas pine pollen remains relatively constant (approximately 30%) in the marine sediments. The higher amount of pine in zone P-2 and P-3 of core 63-013 may be due to the influx of pollen derived from the postglacial pine forest steppe vegetation of the Columbia River Basin, the principal source of sediments in the core, as well as to the selective effects of marine dispersion and destruction. As pollen in a given level of a marine core is probably contemporaneous with other microfossils in that level, marine pollen provides a direct means of correlating marine and continental cores. In cores from the continental slope off western Washington state, the glacial—interglacial boundary interpreted from the change in poUen composition and from the abrupt increase in the frequency of pollen is the same as that determined by the sharp increase in dinoflagellates and from the change in the planktonic foraminiferan/ radiolarian ratio (Barnard, personal communication). Analysis of pollen, radiolaria, and oxygen isotopes in a core from the Pacific Ocean off southern Oregon shows that the response of these three variables to climatic change over the past 80,000 years is generally synchronous (Heusser and others, 1975). The continuous marine pollen record is correlative with pollen records of western Washington covering the same time interval. Marine pollen, used with discretion, can provide information regarding the vegetation of the terrestrial source. The relative continuity of the marine pollen record is particularly important in areas where terrestrial records are interrupted, as in glaciated regions, or where the vegetation record is absent. In the Pacific Northwest, as in many parts of the

L. HEUSSER

world, relatively little information concerning early Pleistocene vegetation is available. First order analyses (40 cm sampling intervals) of a core from the Oregon slope (DSDP Site 175) suggest that pollen assemblages throughout the last 920,000 years are not unUke those of the last 30,000 years. SUGGESTIONS FOR FURTHER READING Faegri, K. and Iversen, J., 1975. Textbook of Pollen Analysis. Hafner, New York, N.Y., 295 pp. [New edition of the compact, information-filled basic palynology text. Includes keys to pollen identification.] Kapp, R.O., 1969. How to know Pollen and Spores. Brown and Co., Dubuque, Iowa, 249 pp. [Inexpensive, illustrated key to major pollen and spore groups.] Manton, A.A. (Editor), 1966. Marine palynology. Mar. Geol., 4(6): 395-582. [Contains general articles as well as specific studies from various parts of the world.] Tschudy, R.H. and Scott, R.A., 1969. Aspects of Palynology. Wiley, New York, N.Y., 510 pp. [An excellent compilation by fourteen authorities on various aspects of palynology ranging from the role of pollen and spores in the plant kingdom to the geologic record of palynomorphs.]

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339 Havinga, A.J., 1964. Investigation into the differential corrosion susceptibility of pollen and spores. Pollen Spores, 6: 621-635. Heusser, C.J., 1969. Modern pollen spectra from the Olympic Peninsula, Washington. Bull. Torrey Bot. Club, 96: 407417. Heusser, C.J., 1973. Modern pollen spectra from Mt. Ranier, Washington. Northwest Sci., 47: 1-8. Heusser, C.J. and Florer, L.E., 1973. Correlation of marine and continental Quaternary pollen records from the northeast Pacific and western Washington. Quaternary Res., 3: 661-670. Heusser, L.E., Shackleton, N.J., Moore, T.C. and Balsam, W.L., 1975. Land and marine records in the Pacific Northeast during the last glacial interval. Geol. Soc. Am., Abstr. Progr., 7: 1113-1114. Hopkins, J.S., 1950. Differential floatation and deposition of coniferous and deciduous tree pollen. Ecology, 31: 633-641. Kemp, E.M. and Barrett, P.J., 1975. Antarctic glaciation and early Tertiary vegetation. Nature, 258: 507-508. Kemp, E.M. and Harris, W.K., 1975. The vegetation of Tertiary islands on the Ninety-East Ridge. Nature, 258: 3 0 3 307. Koreneva, E.V., 1957. Spore-pollen analysis of bottom sediments of the Sea of Okhotsk. Tr. Inst. Okeanol. Akad. Nauk S.S.S.R., 22: 221-251. Koreneva, E.V., 1964. Distribution and preservation of pollen in sediments in the western part of the Pacific Ocean. Tr. Geol. Inst. Akad. Nauk S.S.S.R., 109: 1-88. Koreneva, E.V., 1971. Spores and pollen in Mediterranean bottom sediments. In: B.M. Funnell and W.R. Riedel (Editors), The Micropaleontology of Oceans. Cambridge University Press, New York, N.Y., pp. 361-371. Lubliner-Mianowska, K., 1962. Pollen analysis of the surface samples of bottom sediments in the Bay of Gdansk. Acta Soc. Bot. Polon., 31: 305-312. McAndrews, J.H. and Power, D.M., 1973. Palynology of the Great Lakes, the surface sediments of Lake Ontario. Can. J. Earth Sci., 10: 777-792. Muller, J., 1959. Palynology of recent Orinoco delta and shelf sediments. Micropaleontology, 5: 1-32. Peck, R., 1973. Pollen budget studies in a small Yorkshire catchment. In: H.J.B. Birks and P.G. West (Editors), Quaternary Plant Ecology. Wiley, New York, N.Y., pp. 43-60. Rossignol-Strick, M., 1973. Pollen analysis of some sapropel layers from the deep-sea floor of the eastern Mediterranean. Init. Rep. Deep Sea Drill. Proj., XIII: 971-991. Sangster, A.G. and Dale, H.M., 1964. Pollen grain preservation of under-represented species in fossil spectra. Can. J. Bot., 42: 437-449. Stanley, E.A., 1996a. The application of palynology to oceanography with reference to the northwestern Atlantic. Deep-Sea Res., 13: 921-939. Stanley, E.A., 1966b. The problem of reworked pollen and spores in marine sediments. Mar. Geol., 4: 397-408. Stanley, E.A., 1969. Marine Palynology. Oceanogr. Mar. Biol. Annu. Rev., 7: 277-292. Stover, L.E. and Evans, P.R., 1973. Upper CretaceousEocene spore-pollen zonation, offshore Gippsland Basin, Australia. Geol. Soc. Aust. Spec. Publ., 4: 55-72. Stover, L.E. and Partridge, A.D., 1973. Tertiary and late Cretaceous spores and pollen from the Gippsland Basin, southeastern Australia. R. Soc. Vic. Proc, 85(2): 237-286. Thompson, D., 1972. Paleoecology of the Pamlico Formation, St. Mary's County, Maryland. Thesis, Rutgers University, New Brunswick, N.J. Traverse, A., 1974. Palynologic investigation of two Black Sea cores. AAPG, Mem., 20: 381-388. Traverse, A. and Ginsburg, R.N., 1966. Palynology of the surface sediments of the Great Bahama Bank, as related to water movement and sedimentation. Mar. Geol., 4: 417459. Williams, G.L. and Brideaux, W., 1972. Palynologic analyses of cored sediments from the Grand Banks, Newfoundland. Am. Assoc. Stratigr. Palynol., Abstr. 3rd Meet., 136.