When changes in the frequency and extent of disturbance outstrip the recovery potential of resident communities, the selective removal of species contributes to habitat loss and fragmentation across landscapes. The degree to which habitat change is likely to influence community resilience will depend on metacommunity structure and connectivity. Thus ecological connectivity is central to understanding the potential for cumulative effects to impact upon diversity.

The impact of fishing on chondrichthyan stocks around the world is currently the focus of considerable international concern. Most chondrichthyan populations are of low productivity relative to teleost fishes, a consequence of their different life-history strategies. This is reflected in the poor record of sustainability of target shark fisheries. Most sharks and some batoids are predators at, or near, the top of marine food webs. The effects of fishing are examined at the single-species level and through trophic interactions.

There is considerable controversy about the role of individual species in ecosystem functioning. Most models stress the role of species richness and diversity in ecosystem function, but it is also recognised that individual species or functionally similar species can play prominent roles in assessments of function. There have been relatively few tests of functional replacement by similar species in the marine environment. On intertidal reef platforms in southern New Zealand, six species of fucoid algae co-occur.

In recognition of the need to develop approaches to environmental impact assessment that are both proactive and which take a wider view of environmental change and its causes, there has been increasing interest in the concept of cumulative environmental change and its assessment. We outline a definition and conceptual framework for the analysis of cumulative environmental change. The contribution of geographical information systems (GIS) to the assessment of cumulative effects is considered.

The application of basic ecological concepts to fields of conservation biology and applied environmental sciences is a healthy sign, but before these concepts are widely used, ecology must provide operational definitions and quantifiable methods. Keystone species and interaction strength are concepts with deep practical and theoretical implications. We studied the strength of predation on mussels (Mytilus trossulus) by the keystone seastar Pisaster ochraceus and the whelks Nucella emarginata and N. canaliculata under different environmental conditions in the Oregon intertidal zone.

Cumulative effects (CEs) result from the combined effect of multiple activities over space or time. This implies a persistence through time and often a transmittal mechanism through space. Environmental legislation often requires a broader CE assessment in addition to the more direct, project-specific impacts. Current efforts to evaluate and manage CEs are hampered by the conceptual problems of defining the key issues, specifying the appropriate spatial and temporal scales, and determining the numerous interactions and indirect effects.

Although the timing and magnitude of global climate change is in dispute, the possible effects of such change merit consideration to allow for discussion of policy ramifications and mitigative actions. Climate change may result in sea level rise; water temperature increase; and deviations from present patterns of precipitation, wind, and water circulation. Estuaries may experience loss of marsh habitat, intrusion of marine waters and associated organisms, changes in circulation patterns that affect retention of some indigenous species, and increased hypoxia and storm surges.

Humans impact natural systems in a multitude of ways, yet the cumulative effect of multiple stressors on ecological communities remains largely unknown. Here we synthesized 171 studies that manipulated two or more stressors in marine and coastal systems and found that cumulative effects in individual studies were additive (26%), synergistic (36%), and antagonistic (38%).

Our aim in this paper is to present the first broad-scale quantification of species abundance for rocky intertidal communities along the Pacific coast of North America. Here we examine the community-level marine biogeographical patterns in the context of formerly described biogeographical regions, and we evaluate the combined effects of geographical distance and environmental conditions on patterns of species similarity across this region. Location Pacific coast of North America.

Nearshore estuarine and marine ecosystems—e.g., seagrass meadows, marshes, and mangrove forests—serve many important functions in coastal waters. Most notably, they have extremely high primary and secondary productivity and support a great abundance and diversity of fish and invertebrates. Because of their effects on the diversity and productivity of macrofauna, these estuarine and marine ecosystems are often referred to as nurseries in numerous papers, textbooks, and government-sponsored reports (Boesch and Turner 1984, NRC 1995, Butler and Jernakoff 1999).

The spatial proximity of one habitat to another can strongly influence population and community dynamics We investigated whether the proximity of intertidal oyster reefs to vegetated estuarine habitats, salt marshes, and seagrass beds, affects the abundance and community structure of benthic macroinvertebrates on reefs and predator-prey interactions between mobile predators and bivalves living on reefs. Benthic macroinvertebrate abundance was highest on reefs spatially separated from salt marshes.

Marine scientists have made many recent advances in understanding the connections between the structure of benthic communities, replenishment of populations through dispersal processes, and interactions with the nearshore water mass. In this review, some of the themes and models relating to these processes and interactions are discussed. Benthic–pelagic coupling models are in the early stages of development, but encompass oceanic processes such as upwelling and downwelling, the transport of larvae and their arrival back to shore to settle.

Long-term trends in the response of benthic macrofauna to hydrological conditions were examined in the Lavaca-Colorado Estuary, Texas. Four stations representing a range of salinities in the Lavaca-Colorado Estuary were sampled quarterly for benthic macrofauna and hydrography from April 1988 to October 2008. The relationship between climate variability and local salinity patterns and benthic populations was investigated using the Oceanic Nino Index (ONI), North Atlantic Oscillation (NAO), and North Pacific Index (NPI). Mean salinity declined during the 20 yr study period.

1. A basin approximation was used to analyse distribution patterns of different components of biodiversity (taxonomic richness, endemicity, taxonomic singularity, rarity) and conservation status of freshwater fish fauna in 27 Mediterranean Iberian rivers. 2. Basin area alone explained more than 80% of variation in native species richness. Larger basins featured not only a higher number of native species, but also more endemic and rare species and fewer diversified genera than smaller basins. 3.

The potential for stressors to interact or elicit different responses depending on ecological setting can confound the use of contaminant guidelines or predictions from laboratory-based ecotoxicological studies. However, predicting and identifying multiple stressor effects is challenging because of the wide range of treatment combinations needed for laboratory experiments and the difficulty of conducting field experiments across a range of conditions that may influence stress responses.

1 Top-down control can be an important determinant of ecosystem structure and function, but in oceanic ecosystems, where cascading effects of predator depletions, recoveries, and invasions could be significant, such effects had rarely been demonstrated until recently. 2 Here we synthesize the evidence for oceanic top-down control that has emerged over the last decade, focusing on large, high trophic-level predators inhabiting continental shelves, seas, and the open ocean.