Investigations of the role of competition, predation and abiotic stress in shaping natural communities were a staple for previous generations of ecologists and are still popular themes. However, more recent experimental research has uncovered the largely unanticipated, yet striking influence of facilitation (i.e. positive species interactions) on the organization of terrestrial and aquatic communities. Modern ecological concepts and theories were well established a decade before the current renaissance of interest in facilitation began, and thus do not consider the importance of a wide variety of facilitative interactions. It is time to bring ecological theory up to date by including facilitation. This process will not be painless because it will fundamentally change many basic predictions and will challenge some of our most cherished paradigms. But, ultimately, revising ecological theory will lead to a more accurate and inclusive understanding of natural communities.

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Inclusion of facilitation into ecological theory

http://people.uncw.edu/pawlikj/2008AquatBotNagle.pdf

The habitat function of mangroves for terrestrial and marine fauna: a review

Estuaries exhibit a wide array of human impacts that can compromise their ecological integrity, because of rapid population growth and uncontrolled development in many coastal regions worldwide. Long-term environmental problems plaguing estuaries require remedial actions to improve the viability and health of these valuable coastal systems. Detailed examination of the effects of pollution inputs, the loss and alteration of estuarine habitat, and the role of other anthropogenic stress indicates that water quality in estuaries, particularly urbanized systems, is often compromised by the overloading of nutrients and organic matter, the influx of pathogens, and the accumulation of chemical contaminants. In addition, the destruction of fringing wetlands and the loss and alteration of estuarine habitats usually degrade biotic communities. Estuaries are characterized by high population densities of microbes, plankton, benthic flora and fauna, and nekton; however, these organisms tend to be highly vulnerable to human activities in coastal watersheds and adjoining embayments. Trends suggest that by 2025 estuaries will be most significantly impacted by habitat loss and alteration associated with a burgeoning coastal population, which is expected to approach six billion people. Habitat destruction has far reaching ecological consequences, modifying the structure, function, and controls of estuarine ecosystems and contributing to the decline of biodiversity. Other anticipated high priority problems are excessive nutrient and sewage inputs to estuaries, principally from land-based sources. These inputs will lead to the greater incidence of eutrophication as well as hypoxia and anoxia. During the next 25 years, overfishing is expected to become a more pervasive and significant anthropogenic factor, also capable of mediating global-scale change to estuaries. Chemical contaminants, notably synthetic organic compounds, will remain a serious problem, especially in heavily industrialized areas. Freshwater diversions appear to be an emerging global problem as the expanding coastal population places greater demands on limited freshwater supplies for agricultural, domestic, and industrial needs. Altered freshwater flows could significantly affect nutrient loads, biotic community structure, and the trophodynamics of estuarine systems. Ecological impacts that will be less threatening, but still damaging, are those caused by introduced species, sea level rise, coastal subsidence, and debris/litter. Although all of these disturbances can alter habitats and contribute to shifts in the composition of estuarine biotic communities, the overall effect will be partial changes to these ecosystem components. Several strategies may mitigate future impacts.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0376892902000061

Environmental threats and environmental future of estuaries

The deep-sea communities of the continental slope and rise off the eastern coast of the United States have a remarkably high diversity-measured regionally or locally either as species richness or as the evenness of relative abundance among species. In a 1,500-2,500-m depth range off New Jersey and Delaware, 233 30 x 30-cm samples contained 798 species in 171 families and 14 phyla. Addition of stations from sites to the north and south approximately doubled the number of samples and doubled the number of species to 1,597. Species-area curves do not level off within stations or when stations are added together. Moreover, the proportion of species represented by single individuals is high at all scales of sampling, which indicates that much more sampling is needed to adequately represent the species richness either locally or regionally. Diversity changes very little through time at a single site or with distance along a 180-km transect at a depth of 2,100 m. Diversity is maintained by a combination of bioge...

Deep-Sea Species Richness: Regional and Local Diversity Estimates from Quantitative Bottom Samples

Two main ecological boundaries, ecotone and ecocline, have been defined in landscape ecology At this scale, the estuary represents a boundary between rivers and the sea, but there has been no attempt to fit empirical data for estuaries to these boundary models An extensive data set from the Thames estuary was analysed using multivariate techniques and species-range analysis, in order to investigate whether the ecocline or the ecotone model was most relevant to this estuary Data for periods of high and low freshwater flow allowed the impact of large-scale fluctuations implicit in both models to be determined A continuum of assemblages existed along the salinity gradient from freshwater river to the North Sea, with shifts in the ranges of organisms apparent in response to changes in freshwater flow This pattern closely fits an ecocline model However, the estuary differs from previously defined ecoclines in having two overlapping gradients in the major stressor: from river to mid-estuary for freshwater species and from sea to mid-estuary for marine species We propose, therefore, that the estuary represents a two-ecocline model, with fauna inhabiting the mid-estuary being either freshwater or marine species at the edge of their range, rather than ‘ true estuarine organisms ’ This allows a redefinition of the Remane diagram, with estuarine species removed, and supports previous arguments that brackish-water species do not exist Such two-ecocline models may also exist in other marine systems, such as rocky shores

Ecotone or Ecocline: Ecological Boundaries in Estuaries

1. Introduction to the Marine Environment. Properties of Water. Basic Oceanography. Some Ecological Principles. Larvae and Larval Ecology. Comparison of Terrestrial and Marine Ecosystems. Division of the Marine Environment. 2. Plankton and Plankton Communities. The Phytoplankton. The Zooplankton. Floatation Mechanisms. Primary Production. Factors Affecting Primary Productivity. Primary Productivity of the Biosphere. The Ocean Ecosystem: The Classic Model. The Ocean Ecosystem: A Changing Model. 3. Oceanic Nekton. Composition of the Oceanic Nekton. Environmental Conditions. Adaptations of Oceanic Nekton. Ecology of Nekton. 4. Deep-Sea Biology. Zonation. Sampling the Deep Sea. Environmental Characteristics. Adaptations of Deep-Sea Organisms. Community Ecology of the Benthos. Midwater Community Ecology. 5. Shallow-Water Subtidal Benthic Associations. Environmental Conditions. Unvegetated Sedimentary Environments. Rocky Subtidal Communities. Kelp Beds and Forests. Seagrass Communities. Some Special Communities. Biology of Polar Seas. 6. Intertidal Ecology. Environmental Conditions. Adaptations of Intertidal Organisms. Rocky Shores. Cobble Beaches. Sandy Shores. Muddy Shores. Intertidal Fishes. Birds. 7. Meiofauna. Environmental Characteristics. Composition of the Interstitial Assemblages. Sampling and Extracting Meiofaunna. Adaptations. Ecology. 8. Estuaries and Salt Marshes. Types of Estuaries. Physical Characteristics of Estuaries. The Biota of Estuaries. Adaptations of Estuarine Organisms. Ecology of Estuaries. Salt Marshes. 9. Tropical Communities. Coral Reefs. Mangrove Forests. 10. Symbiotic Relationships. Symbioses of Algae and Animals. Symbioses Among Animals. 11. Human Impact on the Sea. Fisheries. Mariculture. Pollution. Marine Diseases. Drugs From the Sea. Global Warming and Sea Level Change. Concluding Remarks.

James Willard Nybakken

Papers

Marine Biology: An Ecological Approach