Competition and Coexistence


Book Description

The question "Why are there so many species?" has puzzled ecologist for a long time. Initially, an academic question, it has gained practical interest by the recent awareness of global biodiversity loss. Species diversity in local ecosystems has always been discussed in relation to the problem of competi tive exclusion and the apparent contradiction between the competitive exclu sion principle and the overwhelming richness of species found in nature. Competition as a mechanism structuring ecological communities has never been uncontroversial. Not only its importance but even its existence have been debated. On the one extreme, some ecologists have taken competi tion for granted and have used it as an explanation by default if the distribu tion of a species was more restricted than could be explained by physiology and dispersal history. For decades, competition has been a core mechanism behind popular concepts like ecological niche, succession, limiting similarity, and character displacement, among others. For some, competition has almost become synonymous with the Darwinian "struggle for existence", although simple plausibility should tell us that organisms have to struggle against much more than competitors, e.g. predators, parasites, pathogens, and envi ronmental harshness.










Effects of Trawling and Dredging on Seafloor Habitat


Book Description

Concerns over the potential ecological effects of fishing have increased with the expansion of fisheries throughout the marine waters of the United States. Effects of Trawling and Dredging on Seafloor Habitat describes how assessment of fishing impacts depends on gear type, number and location of bottom tows, and the physical and biological characteristics of seafloor habitats. Many experimental studies have documented acute, gear-specific effects of trawling and dredging on various types of habitat. These studies indicate that low mobility, long-lived species are more vulnerable to towed fishing gear than short-lived species in areas where the seabed is often disturbed by natural phenomena. Trawling and dredging may also change the composition and productivity of fish communities dependent on seafloor habitats for food and refuge. The scale of these impacts depends on the level of fishing effort. This volume presents color maps of fishing effort for all regions with significant bottom trawl or dredge fisheries-the first time that such data has been assembled and analyzed for the entire nation.




Recruitment, Colonization and Physical-Chemical Forcing in Marine Biological Systems


Book Description

The 32nd European Marine Biology Symposium was held in Lysekil, Sweden on August 16-22, 1997, organised by Kristineberg Marine Research Station. The selected topics were: `Recruitment and colonisation' and `Physical and Chemical Forcing on Marine Biological Systems', partly reflecting the present research interests at Kristineberg. In this volume, recruitment and colonisation processes cover primarily the dynamics of interspecific interactions within assemblages as well as the effects of hydrodynamic variables. Both laboratory and field studies are emphasised. The contribution of papers within the topic `Physical and Chemical Forcing on Marine Biological Systems' deals with structuring effects of, for example, tides, temperatures, nutrients and hypoxia on the physiology and ecology of marine organisms. The book covers many aspects of marine life. It is our hope that the selected topics will fascinate readers and be of wide interest to students and researchers in marine biology.




Biogeochemical Cycling and Sediment Ecology


Book Description

Oceanographic discontinuities (e. g. frontal systems, upwelling areas, ice edges) are often areas of enhanced biological productivity. Considerable research on the physics and biology of the physical boundaries defining these discontinues has been accomplished (see [I D. The interface between water and sediment is the largest physical boundary in the ocean, but has not received a proportionate degree of attention. The purpose of the Nato Advanced Research Workshop (ARW) was to focus on soft-sediment systems by identifying deficiencies in our knowledge of these systems and defining key issues in the management of coastal sedimentary habitats. Marine sediments play important roles in the marine ecosystem and the biosphere. They provide food and habitat for many marine organisms, some of which are commercially important. More importantly from a global perspective, marine sediments also provide "ecosystem goods and services" [2J. Organic matter from primary production in the water column and contaminants scavenged by particles accumulate in sediments where their fate is determined by sediment processes such as bioturbation and biogeochemical cycling. Nutrients are regenerated and contaminants degraded in sediments. Under some conditions, carbon accumulates in coastal and shelf sediments and may by removed from the carbon cycle for millions of years, having a potentially significant impact on global climate change. Sediments also protect coasts. The economic value of services provided by coastal areas has recently been estimated to be on the order of $12,568 9 10 y" [3J, far in excess of the global GNP.




Ecological Communities


Book Description

This work is the first to focus systematically on a much-debated topic: the conceptual issues of community ecology, including the nature of evidence in ecology, the role of experiments, attempts to disprove hypotheses, and the value of negative evidence in the discipline. Originally published in 1984. The Princeton Legacy Library uses the latest print-on-demand technology to again make available previously out-of-print books from the distinguished backlist of Princeton University Press. These editions preserve the original texts of these important books while presenting them in durable paperback and hardcover editions. The goal of the Princeton Legacy Library is to vastly increase access to the rich scholarly heritage found in the thousands of books published by Princeton University Press since its founding in 1905.




Structural Equation Modeling and Natural Systems


Book Description

This book, first published in 2006, presents an introduction to the methodology of structural equation modeling, illustrates its use, and goes on to argue that it has revolutionary implications for the study of natural systems. A major theme of this book is that we have, up to this point, attempted to study systems primarily using methods (such as the univariate model) that were designed only for considering individual processes. Understanding systems requires the capacity to examine simultaneous influences and responses. Structural equation modeling (SEM) has such capabilities. It also possesses many other traits that add strength to its utility as a means of making scientific progress. In light of the capabilities of SEM, it can be argued that much of ecological theory is currently locked in an immature state that impairs its relevance. It is further argued that the principles of SEM are capable of leading to the development and evaluation of multivariate theories of the sort vitally needed for the conservation of natural systems.