Techniques developed for enclosing viable natural planktonic ecosystems pro vided the opportunity for prolonged and detailed investigation of dynamic events within the pelagic system of a known water body. Recent investigations into plankton ecology, using enclosure systems in dif ferent marine environments, are discussed in relation to the data obtained from the Nanaimo, British Columbia, Canada, plastic-sphere experiments of 1960 and 1962. Three types of modern enclosure experiments are recognized: floating systems within nutrient levels maintained or running down, and benthic attached systems. The review largely discusses results from the two kinds of floating systems. Processes at several trophic levels have been investigated in enclosures. This review attempts to draw together details from all experimental systems to emphasize the enclosures' contribution to our understanding of planktonic systems. Enclosures made it possible to examine primary production processes, particularly in relation to inorganic nutrient availability and water-column sta bility. Recent experiments have used the understanding of these processes as a management technique in maintaining different planktonic systems. Relation ships between primary and secondary trophic levels are not always easy to inter pret, since the growth of primary carnivore populations can often determine the survival of zooplankton populations. Nevertheless, the development of co horts of herbivorous zooplankton has been followed in several enclosures, yield ing useful information on development times and production rates. In enclosed systems it is thus possible to directly relate tertiary level production to inorganic nutrient input, and to calculate production rates and exchange efficiencies at several trophic levels.

Modem biology owes much to the study of favorable model systems which fa cilitates the realization of critical experiments and results in the introduction of new concepts. Examples of such systems are numerous and studies of them are regularly recognized by the scientific community. The 1983 Nobel Prize in Med icine and Physiology is a magnificent example in which com plants served as the experimental model. In a manner somewhat more modest, other biological systems have attracted recognition due to their critical phylogenetic position, or indeed because of their uniqueness which distinguishes them from all other organisms. Assuredly, among the whole assemblage ofliving organisms, sponges stand out as worthy of interest by scientists: they are simultaneously models, an important group in evolution, and animals unlike others. As early as the beginning of this century, sponges appeared as exceptional models for the study of phenomena of cell recognition. Innumerable works have been dedicated to understanding the mechanisms which assure the reaggregation of dissociated cells and the reconstitution of a functional individual. Today, re search on these phenomena is at the ultimate, molecular level. Through an as semblage of characteristics the sponges are, based upon all available evidence, the most primitive Metazoans. Their tissues-perhaps one can say their cell groups-are loosely assembled (they possess no tight or gap junctions), cell dif ferentiation appears highly labile, and they do not develop any true organs. But, they are most certainly Metazoans.

This timely volume provides a comprehensive account of the natural history of the organisms associated with the deep-sea floor and examines their relationship with this inhospitable environment--perhaps the most remote and least accessible location on the planet. The authors begin by describing the physical and chemical nature of the deep-sea floor and the methods used to collect and study its fauna. Then they discuss the ecology of the deep sea by exploring spatial patterns, diversity, biomass, vertical zonation, and large-scale distribution of organisms. Subsequent chapters review current knowledge of feeding, respiration, reproduction, and growth processes in these communities. The unique fauna of hypothermal vents and seeps are considered separately. Finally, there is a pertinent discussion of human exploitation of deep-sea resources and potential use of this environment for waste disposal.

The Biology of Tardigrades is the only modern comprehensive account of marine and freshwater tardigrades. It contains the first taxonomic review for over a decade in addition to covering every aspect of their biology.

Introduction to Marine Biogeochemistry focuses on the ocean's role in the biogeochemical cycling of selected elements and the impact of humans on the cycling of these elements. Among the topics covered are the chemical composition of seawater from the perspectives of elemental speciation and the impacts of solutes on water's physical behavior; biogeochemical phenomena which control accumulation and preservation of marine sediments; marine chemistry of radioactive and stable isotopes; and seawater pollution. The book contains many examples as well as steady-state models to aid readers in understanding this growing and complex science.. - The focus of Introduction to Marine Biogeochemistry is the concept of the ocean as a system, linking land and atmospheric processes - The text integrates the most current research, allowing students to learn concepts in context - Includes detailed coverage of computational aspects

The key to preserving and managing biodiversity is understanding which processes are important at different scales, and how changes affect different components of biodiversity. In this book, existing theories on diversity are synthesised into a logical framework. Global and landscape-scale patterns of biodiversity are described in the first section. In the second, the spatial and temporal dynamics of diversity are emphasised. The third section develops an integrated set of mechanistic explanations for diversity patterns at the levels of population, community, ecosystem and landscape. Finally, case studies examine diversity patterns in marine and terrestrial ecosystems and the effects of biological invasions. The book concludes with a discussion of the economics of preserving biological diversity. This book will interest research workers and students of ecology, biology and conservation.