Environmental Micropaleontology

For many decades, applied paleontology has concentrated on finding energy resources. Despite the extensive, but almost exclusive, use of micropaleontology in petroleum exploration during the last half-century, foraminifera were used much earlier to date strata in a water well near Vienna, Austria in 1877. Further studies followed in the United States, but it was primarily J. A. Udden of Augustana College (Illinois), who, in 1911, began to use microfossils to correlate water wells in the United States. Udden would later forsake academe to become head of the newly organized Bureau of Economic Geology of Texas, where he shifted application of microfossils from water to petroleum. Bandy et al. (1964a,b; 1965a,b) were among only a handful of workers during the succeeding years who examined the response of foraminiferal populations to environmental disturbance (large inputs of sewage in shallow marine waters). Bandy et al.’s studies lay dormant, however, probably because the environmental movement had not yet fully developed and because of the heavy emphasis of applied micropaleontology on petroleum exploration (Bandy’s results may also have been confounded by the effects of low salinity; see Debenay et al., Ch. 2).

The aim of ecological studies is to establish the relationship between the biota (e.g., community structure of populations of living organisms including standing crop, species abundance, and species diversity) and the attributes of the environment (physical, chemical, and biological). Such studies may be spatial involving a suite of samples collected over a geographic area during a very short time interval (days), or temporal, where samples are collected from one (or more) sites over an extended period of time (ideally several decades). Spatial studies give a snapshot over a broad area, whereas temporal studies give a near-continuous record of a very small area.

Foraminifera are extensively used in different fields of earth and environmental sciences by virtue of several factors such as (1) a hard exoskeleton, which records fundamental environmental changes and evolutionary processes of earth history, (2) small size and, consequently, high abundance in small samples, (3) wide distribution over all marine environments, (4) high taxonomic diversity, and (5) very short reproductive cycles (month to year), which make them excellent recorders of environmental changes covering a short time span.

Tarawa Atoll, the seat of government and main population center for the Republic of Kiribati, is located in the western Pacific Ocean at latitude 1°28′N and longitude 173°00′E (Fig. 1). The 35 islands of the republic are divided into three main groups, the Gilbert, Line, and Phoenix islands, with Tarawa Atoll located in the central Gilbert Group.

Human activities are impacting ecosystems on a global scale; Vitousek et al. (1997a) asserted that no ecosystem on the Earth’s surface is free of human influence. The land, atmosphere, and hydrosphere have all been altered to varying degrees. Up to 50% of the Earth’s land area has been transformed or degraded (Vitousek et ai., 1997a). As a result of stratospheric ozone depletion, intensities of biologically damaging ultraviolet radiation (UVB) at 20°N latitude between April and August now exceed the June 1969 (summer solstice) maximum (Shick et al., 1996). Carbon dioxide concentration in the atmos- phere has increased by nearly 30% since the beginning of the Industrial Revolution (Schimel et ai., 1995), with potential influences ranging from climate changes to altered ocean chemistry. Human activities have effectively doubled the annual transfer of nitrogen from the atmospheric pool of N₂ to biologically-available fixed nitrogen (Schnoor et al., 1995; Vitousek et al., 1997b). Much of this fixed nitrogen, along with nitrous oxides from fossil-fuel burning (e.g., Prinn et al., 1990), is washed by the rains into aquatic systems.

Ostracoda have long been known to be useful as indicators of variations in the environment, such as salinity, pH, Eh, and temperature, and more recent studies have focused on pollution. Initially, these studies concentrated on freshwater species and, indeed, most of the subsequent work has also been done using freshwater species. Ostracodes were used to show the influence of a sewage discharge into a stream in Israel (Rosenfeld and Ortel, 1983). Later, other studies worked on the effects of pesticides on freshwater species in ricefields (Lim and Wong, 1986). Pioneering work was done in France by Bodergat (1978) on the effects of cerium on the environment through studying the valves of marine water species and also on the effects of industrial and urban water from a large city in Japan on the marine ostracodes (Bodergat and Ikeya, 1988). Another study by Bodergat et al. (1997) was done on natural pollution or eutrophication. Following changes observed in the faunas at Tarawa Atoll, Republic of Kiribati, (Eagar, 1998), where the number of species had recently declined, a study was undertaken in New Zealand on the extreme situation, of a direct sewer discharge from a large city into the marine environment (Eagar, 1999; see also in this volume Ebrahim, Ch. 4; Hallock, Ch. 5; Rosenfeld et al., Ch. 7; Schomhikov, Ch. 8; Ishman, Ch. 16).

Organic pollution produces changes in the aquatic environment. Effluent reduces the dissolved-oxygen concentration as a result of decomposition of organic material and increases the levels of ammonia and phosphate, and both the biochemical oxygen demand (BOD) and chemical oxygen demand (COD). These affect the stream fauna so that different communities often show a zonation that characterizes distinct sections downstream of the discharge (Kolkwitz, 1950; Hynes, 1960; Liebmann, 1962; Hawkes, 1962; Chandler, 1970). This biotic zonation led to the traditional classification of water quality: a heavily polluted (polysaprobic) zone, a moderate (mesosaprobic) polluted zone (divided into two subzones, alpha and beta), and a slightly (oligo-saprobic) polluted zone, also known as the recovery zone, which indicates an advanced stage of self-purification of the river.

Ostracoda are a diverse ( >40,000 species) class of crustaceans. They are known from the Cambrian, and recent ostracodes dwell in all possible aquatic biotopes, from oceanic hadal to humid land biotopes and subterranean waters, in which they form specific complexes of species.

Foraminifers are increasingly used as bioindicators of environments. Their community structure provides information on the general characteristics of the environment, especially in highly changing paralic environments (e.g., Hayward and Hollis, 1994), and some species are sensitive to specific environmental parameters. Test morphology may also be related to environmental characteristics and is sometimes used as a bioindicator. The size and the density of pores, e.g., have been considered as indicators of dissolved oxygen concentration (Sen Gupta and Machain-Castillo, 1993).

Foraminifera play an important role in the global biogeochemical cycles of inorganic and organic compounds, which makes them one of the most significant of marine and marginal marine taxa (Lipps, 1983; Anderson, 1988; Lee and Anderson, 1991). The hardtests of foraminifera are preserved long after they die and can be studied in the fossil record. Therefore, foraminifera are often perceived more as a subject of geology and paleontology than of cell biology and zoology, and both paleontologists and zoologists have devoted more attention to the study of foraminiferal shells than the living specimens; ironically, however, molecular mechanisms of shell formation are unknown. Systematics and paleontology of foraminifera are studied in more detail than their biology, ecology, and ecotoxicology. The cytophysiology, biochemistry, molecular biology, and chemical ecology of foraminifera are particularly poorly understood.

This chapter summarizes the first attempts to use dinoflagellate cysts as indicators of eutrophication and industrial pollution. This is new work, published just recently, and though so far based on only a few studies it shows a clear potential for development as a robust working method for environmental science. In contrast to almost all other microfossil groups included in this book, the cysts used here are acid-resistant and therefore not subject to the dissolution that sometimes affects the mineralized shells of foraminifers and diatoms. Furthermore, they provide environmental signals from the first level of the food web—primary production.

Many silled fjords have a natural potential for developing dysoxic and even anoxic bottom water conditions. This often occurs in microtidal silled fjords with an estuarine circulation pattern, where surface or transitional lowdensity water extends down to sill depth and thereby inhibits frequent renewals of the denser deep basin water. The oxygen regimes in such fjords are very sensitive to increased fluxes of organic carbon whether due to natural or anthropogenic causes.

This study investigates the sediment source for washover fans and the use of natural (foraminifera) and artificial (glass bead) tracers to quantify deposition and mixing in back-barrier marsh environments along the South Carolina coast. Erosion and deposition along South Carolina’s coast are processes of growing interest. Recent storm events have demonstrated the economic effects of such natural agents and the need to better understand the frequency of major storms in relation to barrier-island migration, sediment supply, and evolution. Foraminiferal assemblages provide insight into back-barrier deposition rates, including potential storm-generated washover intervals, and may help to identify processes acting on an evolving barrier island in a transgressive setting.

The South Florida ecosystem is complex and dynamic. The evolution of the ecosystem has been influenced by the influx of freshwater related to natural hydroperiods in the Everglades wetland, to hurricane events, and to sea-level rise, as well as to anthropogenic changes, such as alteration of the natural hydroperiod and changes in flow between Florida Bay and the Atlantic. Reduced fish and shellfish populations, altered seagrass densities and die-offs (Robblee et al., 1991), and increased phytoplankton blooms show that the ecosystem has undergone significant change, the causes of which remain poorly understood (VanArman, 1984; Boesch et al., 1993). While there have been detailed studies of aquatic animals and vegetation conditions, changes in the benthic community have not been as rigorously addressed.

Rivers are major transport elements in the global nutrient cycle: dissolved and particulate matter is brought from the continents to deltaic areas, where it is spread over the shelves and beyond. Basically, most of the transported material consists of erosion products, including all essential nutrients for life. Additionally, organic remains from terrestrial life are swept into the shallow marine realm. The total process forms the basis of the marine food web, and through marine primary production the pelagic, and later on the benthic, foodweb is fueled.

The Savannah River Site (SRS) occupies 310 km2 within Aiken, Barnwell, and Allendale counties in southwestern South Carolina, U.S.A. (Fig. 1). Bedrock (Paleozoic metamorphic and Triassic clastic rock) and overlying Coastal plain sediments (Upper Cretaceous through Holocene unconsolidated sediments) constitute the hydrologic system beneath the SRS and surrounding areas (Fig. 2). Direction of groundwater flow in the aquifers at SRS is primarily toward the Savannah River and its tributaries. Aquifers in the Cretaceous sediments are the primary source of drinking water for the SRS and surrounding communities.

London is one of the world’s most important capital cities, having expanded over 2000 years since being founded by the Romans (as Londinium) during the time of their occupation of Britain. The original settlement was located on a gravel bank very close to the present City of London. This relatively high location afforded protection from the occasional high tides that, even then, had begun to encroach on the flat marshland that bordered the nearby river.