Definitions of diversity. Measuring species diversity. Choosing an index and interpreting diversity measures. Sampling problems. Structural diversity. Applications of diversity measures. Summary.

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Ecological Diversity and its Measurement

Since 65 million years ago (Ma), Earth's climate has undergone a significant and complex evolution, the finer details of which are now coming to light through investigations of deep-sea sediment cores. This evolution includes gradual trends of warming and cooling driven by tectonic processes on time scales of 10(5) to 10(7) years, rhythmic or periodic cycles driven by orbital processes with 10(4)- to 10(6)-year cyclicity, and rare rapid aberrant shifts and extreme climate transients with durations of 10(3) to 10(5) years. Here, recent progress in defining the evolution of global climate over the Cenozoic Era is reviewed. We focus primarily on the periodic and anomalous components of variability over the early portion of this era, as constrained by the latest generation of deep-sea isotope records. We also consider how this improved perspective has led to the recognition of previously unforeseen mechanisms for altering climate.

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Trends, Rhythms, and Aberrations in Global Climate 65 Ma to Present

Ecological extinction caused by overfishing precedes all other pervasive human disturbance to coastal ecosystems, including pollution, degradation of water quality, and anthropogenic climate change. Historical abundances of large consumer species were fantastically large in comparison with recent observations. Paleoecological, archaeological, and historical data show that time lags of decades to centuries occurred between the onset of overfishing and consequent changes in ecological communities, because unfished species of similar trophic level assumed the ecological roles of overfished species until they too were overfished or died of epidemic diseases related to overcrowding. Retrospective data not only help to clarify underlying causes and rates of ecological change, but they also demonstrate achievable goals for restoration and management of coastal ecosystems that could not even be contemplated based on the limited perspective of recent observations alone.

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Historical overfishing and the recent collapse of coastal ecosystems.

Interactions between organisms are a major determinant of the distribution and abundance of species. Ecology textbooks (e.g., Ricklefs 1984, Krebs 1985, Begon et al. 1990) summarise these important interactions as intra- and interspecific competition for abiotic and biotic resources, predation, parasitism and mutualism. Conspicuously lacking from the list of key processes in most text books is the role that many organisms play in the creation, modification and maintenance of habitats. These activities do not involve direct trophic interactions between species, but they are nevertheless important and common. The ecological literature is rich in examples of habitat modification by organisms, some of which have been extensively studied (e.g. Thayer 1979, Naiman et al. 1988).

Organisms as ecosystem engineers

The management and conservation of the world's oceans require synthesis of spatial data on the distribution and intensity of human activities and the overlap of their impacts on marine ecosystems. We developed an ecosystem-specific, multiscale spatial model to synthesize 17 global data sets of anthropogenic drivers of ecological change for 20 marine ecosystems. Our analysis indicates that no area is unaffected by human influence and that a large fraction (41%) is strongly affected by multiple drivers. However, large areas of relatively little human impact remain, particularly near the poles. The analytical process and resulting maps provide flexible tools for regional and global efforts to allocate conservation resources; to implement ecosystem-based management; and to inform marine spatial planning, education, and basic research.

/pdf/a-global-map-of-human-impact-on-marine-ecosystems-1r5xgg00oe.pdf

A Global Map of Human Impact on Marine Ecosystems

The sediments drilled during Leg 14 of the Deep Sea Drilling Project off northwestern Africa and northeastern South America comprise a wide range of Cretaceous and Tertiary deep-sea facies. The major processes controlling the distribution of these facies are the changing patterns of supply and preservation of biogenous matter, terrigenous influx, and erosion and redeposition on the ocean floor. The sequence of mid-Tertiary to Quaternary sediments can be described as an evolution from a "north Pacific" to a typical "Atlantic" facies, contingent upon a change in deep-sea circulation from ascending (estuarine) to descending (lagoonal), and a decreasing orogenic influence. For older sediments, recent counterparts are not available in many cases, and the reconstruction of the ncient environments involves unfamiliar sets of geochemical, climatological, and geographic variables, in addition to diagenesis. End_of_Article - Last_Page 604------------

Cretaceous and Tertiary Deep-Sea Sediments from Atlantic Ocean: ABSTRACT

This informal report was prepared from the shipboard files by the scientists who participated in the cruise. The report was assembled under time constraints and is not considered to be a formal publication which incorporates final works or conclusions of the participating scientists. The material contained herein is privileged proprietary information and cannot be used for publication or quotation. Any opinions, findings and conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the views of the National Science Foundation, the participating agencies, ABSTRACT During Leg 175, thirteen sites were occupied off the western coast of Africa (Congo, Angola, Namibia, and South Africa), and 40 holes were drilled using advanced hydraulic piston coring and the extended core barrel method. The goal is to reconstruct the late Neogene history of the Benguela Current and the associated upwelling regimes between 5° and 32°S. The area investigated contains one of the greatest upwelling regions of the world, intermediate in intensity between the systems off Peru and California. The Angola-Benguela Current system with its associated upwelling regions ("ABC-system") is characterized by organic-rich sediments that contain an outstanding record of productivity history, which can be read on a very fine scale. In addition, this environment provides an excellent setting for natural experiments in diagenesis. The individual transects selected for drilling within the ABC-system reflect a compromise among geographic coverage, accessibility, quality of sedimentary record, and time constraints. Variations in productivity are generated in different ways, within different geographic settings (off the Congo, near the Angola Dome, at Walvis Ridge, in the upwelling cells south of the ridge). One of the major goals is to document fluctuations in productivity in these different settings in relationship to large-scale climate change within the late Neogene, including the onset of glacial cycles in the Northern Hemisphere. Another major goal is to tie the fluctuations in oceanic conditions to the corresponding changes in climate on the adjacent continent. Most of the sites drilled have high sedimentation rates (ca. 100 m/m.y.), which offers an opportunity to develop detailed paleoceanographic records, with a resolution near 1000 yr. Sediments are largely diatomaceous and carbonate-rich clays with variable (and occasionally very high) organic carbon contents. Analysis of these sediments will greatly extend and refine results concerning paleoceanography and paleoclimate of the late Neogene that were provided by Deep Sea Drilling Project Sites 362 and 532. contain the …

http://www-odp.tamu.edu/publications/prelim/175_prel/175prelim.pdf

Ocean drilling program leg 175 preliminary report benguela current

The main factor in all processes on the surface of Earth, including geological ones involving sedimentation, is commonly thought to be the energy from the sun, which provides for exogenic forcing. However, major changes in geography (such as the distribution of land and sea and elevations) are wrought by endogenic forcing, that is, forcing that comes from the mantle and drives tectonics, including plate motions. In addition, there is astronomic forcing, which works through the Earth’s orbital features, through impact, or by cosmic radiation. Milankovitch forcing is orbital and modifies solar forcing. Apparently it is responsible for much of the ice-age fluctuations. Exogenic (solar) forcing directly involves the radiation balance (which is part of the everyday climate system), that is, the equilibrium between incoming solar heat and outgoing radiation from the Earth, an equilibrium that keeps the planet at a given average temperature (Fig. 9.1). The latest (and most rapid) of changes are from human activities, presumably to be counted as “exogenic” since they work by enhancing solar input (i.e., blocking output of heat radiation to space). The changes are commonly (quite properly) categorized as “anthropogenic,” emphasizing human causation.

Imprint of Climatic Zonation on Marine Sediments

As mentioned in the introduction, deep-Sea Deposits were first explored in a comprehensive fashion during the British Challenger Expedition (1873–1876) Many thousands of samples were subsequently studied by John Murray (1841–1914), naturalist on the Challenger He and his co-worker A F Renard published a weighty report on the results, which laid the foundation for all later work in this field of research The first great step beyond Murray’s work were the results of the German Meteor Expedition, almost half a century later (1927–1929) A new branch of oceanography started with the recovery of long cores by the Swedish Albatross Expedition (1947–1949), that is, Pleistocene oceanography It revolutionized our understanding of the great Ice Ages Another great step came in 1968 with Glomar Challenger and the Deep Sea Drilling Project, which provided the samples for Tertiary and Cretaceous ocean history

Deep-Sea Sediments — Patterns, Processes, and Stratigraphic Methods

The productivity of the world ocean (that is, its biological output) is of interest to marine geologists mainly for two reasons: (1) the distribution of biogenic particles (calcareous and opaline skeletal material, shells) and of organic matter depends on the patterns of productivity of the sea and (2) the history of productivity drives the evolution (that is, the geologic history) of organisms that eat food, which means all of the marine animals, including those of the zooplankton Since the green primary producers need nutrients, they must evolve as well to adjust to changing nutrient supply There are (at least) two more reasons to study productivity: (3) the evolution of marine microbes (4) In economic geology, of course, the history of marine productivity is important in the origin of oil and gas

Wolfgang H Berger

Papers

Cretaceous and Tertiary Deep-Sea Sediments from Atlantic Ocean: ABSTRACT

Ocean drilling program leg 175 preliminary report benguela current

Imprint of Climatic Zonation on Marine Sediments

Deep-Sea Sediments — Patterns, Processes, and Stratigraphic Methods

Productivity of the Ocean and Implications