Food chain length and omnivory determine the stability of a marine
... time. Predators and omnivory could influence temporal stability through effects on abundance (the ‘abundance’ effect), summed variance across taxa (the ‘portfolio effect’) or summed covariances among taxa (the ‘covariance effect’). 3. We found that increasing food chain length by predator addition de ...
... time. Predators and omnivory could influence temporal stability through effects on abundance (the ‘abundance’ effect), summed variance across taxa (the ‘portfolio effect’) or summed covariances among taxa (the ‘covariance effect’). 3. We found that increasing food chain length by predator addition de ...
as a PDF
... low in most streams world wide. but a few streams are very productive (Figure 15.1) although not as productive as streams supporting warm-water species where annual production can exceed 100glmzlyr (Naiman 1976). Many factors influence productivity. Physical characteristics of the stream environment ...
... low in most streams world wide. but a few streams are very productive (Figure 15.1) although not as productive as streams supporting warm-water species where annual production can exceed 100glmzlyr (Naiman 1976). Many factors influence productivity. Physical characteristics of the stream environment ...
climate driven trophic cascades affecting seabirds around the british
... After flourishing during the second half of the twentieth century, many North Sea seabird populations are now in decline. Much evidence is accumulating that climate change is driving these negative trends in growth rate. Climate driven changes in the physical environment may affect seabirds both dir ...
... After flourishing during the second half of the twentieth century, many North Sea seabird populations are now in decline. Much evidence is accumulating that climate change is driving these negative trends in growth rate. Climate driven changes in the physical environment may affect seabirds both dir ...
Predicted and Observed Feeding Rates of the Spinose Planktonic
... of SCUBA-collected foraminifera also showed a wide variability, averaging one copepod captured every 3.3 days, and were generally within the range of feeding rates predicted by the model. ...
... of SCUBA-collected foraminifera also showed a wide variability, averaging one copepod captured every 3.3 days, and were generally within the range of feeding rates predicted by the model. ...
Top-down and bottom-up diversity cascades in detrital vs. living food
... communities, but the indirect (ÔcascadingÕ) effects of top-down and bottom-up forces on diversity at different trophic levels are not well resolved in terrestrial systems. Manipulations of predators or resources can cause direct changes of diversity at one trophic level, which in turn can affect div ...
... communities, but the indirect (ÔcascadingÕ) effects of top-down and bottom-up forces on diversity at different trophic levels are not well resolved in terrestrial systems. Manipulations of predators or resources can cause direct changes of diversity at one trophic level, which in turn can affect div ...
organic matter flow in stream food webs with reduced detrital
... and Williams 1996). It also has been suggested that highly resolved binary food webs will provide insight into ecosystem function (Bengtsson and Martinez 1996). A more fundamental problem with these food webs is that all links were considered equal, because links were not quantified in terms of ener ...
... and Williams 1996). It also has been suggested that highly resolved binary food webs will provide insight into ecosystem function (Bengtsson and Martinez 1996). A more fundamental problem with these food webs is that all links were considered equal, because links were not quantified in terms of ener ...
Bridge under troubled water: Turbulence and niche partitioning in
... inevitable at high niche overlap, but such divide between competitors may be bridged if environmental circumstances displace competitor niches to enhance partitioning. Foraging-niche dimension can be influenced by environmental characteristics, and if competitors react differently to such conditions ...
... inevitable at high niche overlap, but such divide between competitors may be bridged if environmental circumstances displace competitor niches to enhance partitioning. Foraging-niche dimension can be influenced by environmental characteristics, and if competitors react differently to such conditions ...
CHANGES IN TURBULENT MIXING SHIFT COMPETITION FOR
... buoy 6 (Fig. 1). The temperature loggers recorded the temperature every 10 minutes. Vertical turbulent diffusivities can be calculated from detailed profiles of the temperature microstructure (Imberger and Ivey 1991, Kocsis et al. 1999, MacIntyre 1999, Sharples et al. 2001). This requires that the t ...
... buoy 6 (Fig. 1). The temperature loggers recorded the temperature every 10 minutes. Vertical turbulent diffusivities can be calculated from detailed profiles of the temperature microstructure (Imberger and Ivey 1991, Kocsis et al. 1999, MacIntyre 1999, Sharples et al. 2001). This requires that the t ...
small networks but not small worlds: unique aspects of food web
... average connectance over all 16 webs is 0.11 (SD = 0.09), similar to mean connectance values reported for other reliable sets of community food webs (Martinez 1992: 5 webs, mean C = 0.11, SD = 0.03; Havens 1992: 50 webs, mean C = 0.10, SD = 0.04). Characteristic path lengths range from 1.33 to 3.74, ...
... average connectance over all 16 webs is 0.11 (SD = 0.09), similar to mean connectance values reported for other reliable sets of community food webs (Martinez 1992: 5 webs, mean C = 0.11, SD = 0.03; Havens 1992: 50 webs, mean C = 0.10, SD = 0.04). Characteristic path lengths range from 1.33 to 3.74, ...
Freshwater autotrophic picoplankton: a review
... Autotrophic picoplankton (APP) are distributed worldwide and are ubiquitous in all types of lakes of varying trophic state. APP are major players in carbon production in all aquatic ecosystems, including extreme environments such as cold ice-covered and/or warm tropical lakes and thermal springs. Th ...
... Autotrophic picoplankton (APP) are distributed worldwide and are ubiquitous in all types of lakes of varying trophic state. APP are major players in carbon production in all aquatic ecosystems, including extreme environments such as cold ice-covered and/or warm tropical lakes and thermal springs. Th ...
Daphnia as keystone predators - Orlando Sarnelle
... 120.039 W), a naturally eutrophic lake in southern California, USA. The lake is thermally stratified for much of the year, leading to persistent anoxia in the deep waters. Total phosphorus (dissolved plus particulate) concentrations in the mixed layer average about 10 mM during winter mixing period ...
... 120.039 W), a naturally eutrophic lake in southern California, USA. The lake is thermally stratified for much of the year, leading to persistent anoxia in the deep waters. Total phosphorus (dissolved plus particulate) concentrations in the mixed layer average about 10 mM during winter mixing period ...
chapter 6 interplay between scale, resolution, life history and food
... indirect. This leads us to a very fundamental question: How are food webs structured? The answer is not derived only from the measurement of nature, but also depends on conceptualization of the model. Winemiller and Layman (2005) recently described four alternative concepts of food web structure. Th ...
... indirect. This leads us to a very fundamental question: How are food webs structured? The answer is not derived only from the measurement of nature, but also depends on conceptualization of the model. Winemiller and Layman (2005) recently described four alternative concepts of food web structure. Th ...
Growth physiology and fate of diatoms in the ocean: a review
... Diatoms are a major component of phytoplankton community. They tend to dominate under natural high-nutrient concentrations, as well as during artificial Fe fertilisation experiments. They are main players in the biogeochemical cycle of carbon (C), as they can account for 40% of the total primary pro ...
... Diatoms are a major component of phytoplankton community. They tend to dominate under natural high-nutrient concentrations, as well as during artificial Fe fertilisation experiments. They are main players in the biogeochemical cycle of carbon (C), as they can account for 40% of the total primary pro ...
When is a trophic cascade a trophic cascade?
... interaction as a trophic cascade, regardless of the exact mechanism by which the indirect interaction occurs (e.g. trophic cascades would include strong effects arising from indirect interactions, such as keystone or intraguild predation). Second, this definition (which includes both species-level a ...
... interaction as a trophic cascade, regardless of the exact mechanism by which the indirect interaction occurs (e.g. trophic cascades would include strong effects arising from indirect interactions, such as keystone or intraguild predation). Second, this definition (which includes both species-level a ...
Chinese Mitten Crab
... and clams. In California, adult crabs have become a major nuisance to anglers, taking a variety of baits ranging from ghost shrimp to shad. Predatory fishes, including sturgeon, striped bass and channel catfish, as well as bullfrogs, raccoons, river otters and wading birds may prey upon the crab. ...
... and clams. In California, adult crabs have become a major nuisance to anglers, taking a variety of baits ranging from ghost shrimp to shad. Predatory fishes, including sturgeon, striped bass and channel catfish, as well as bullfrogs, raccoons, river otters and wading birds may prey upon the crab. ...
Are there real differences among aquatic and terrestrial food webs?
... studies have perhaps been overemsmall invertebrate consumers phasized relative to more synthetic (1–5 m2 and days–months)11. comparative analyses, the degree to which we can generalize Second, recent reviews and meta-analyses14–16 in freshsimilarities and differences across ecosystems is limited. wa ...
... studies have perhaps been overemsmall invertebrate consumers phasized relative to more synthetic (1–5 m2 and days–months)11. comparative analyses, the degree to which we can generalize Second, recent reviews and meta-analyses14–16 in freshsimilarities and differences across ecosystems is limited. wa ...
Species interactions and energy transfer in aquatic food webs
... Zooplankton feeding ecology Zooplankton species are dominant intermediate species in aquatic ecosystems and important prey items for many fish species (Stibor et al. 2004) due to their high abundance and high nutrient content (Beaugrand 2003). Yet, integrated assessment of how zooplankton species’ d ...
... Zooplankton feeding ecology Zooplankton species are dominant intermediate species in aquatic ecosystems and important prey items for many fish species (Stibor et al. 2004) due to their high abundance and high nutrient content (Beaugrand 2003). Yet, integrated assessment of how zooplankton species’ d ...
Ward et al. - Massachusetts Institute of Technology
... importance of both nutrient and grazer controls. The model suggests that zooplankton : phytoplankton (Z : P) biomass ratios may vary from an order of 0.1 in the oligotrophic gyres to an order of 10 in upwelling and highlatitude regions. Global estimates of the strength of bottom-up and top-down cont ...
... importance of both nutrient and grazer controls. The model suggests that zooplankton : phytoplankton (Z : P) biomass ratios may vary from an order of 0.1 in the oligotrophic gyres to an order of 10 in upwelling and highlatitude regions. Global estimates of the strength of bottom-up and top-down cont ...
Compensation masks trophic cascades in complex food
... the feeding relationships between interacting species within an ecosystem. Understanding how the complexity of these networks influences their response to changing top-down control is a central challenge in ecology. Here, we provide a model-based investigation of trophic cascades — an oft-studied ec ...
... the feeding relationships between interacting species within an ecosystem. Understanding how the complexity of these networks influences their response to changing top-down control is a central challenge in ecology. Here, we provide a model-based investigation of trophic cascades — an oft-studied ec ...
Scientist and Stakeholder Views on the Delta Ecosystem
... A central water policy challenge facing California is how to improve the management of the Sacramento– San Joaquin Delta’s aquatic ecosystem. The Delta is a network of mostly manmade islands and channels at the confluence of the Sacramento and San Joaquin Rivers. Together with the San Francisco Bay, ...
... A central water policy challenge facing California is how to improve the management of the Sacramento– San Joaquin Delta’s aquatic ecosystem. The Delta is a network of mostly manmade islands and channels at the confluence of the Sacramento and San Joaquin Rivers. Together with the San Francisco Bay, ...
Cercopagis pengoi - New Important Food Object of the
... development than the previous summer, C. pengoi was first recorded in the plankton on 30 July, when the surface water temperature rose to 13.5 °C, near the Island UlkoTammio with a density of 60 ind • m-3 (Fig. 2). In comparison, we can note that in summer 1999 the same water temperature occurred mu ...
... development than the previous summer, C. pengoi was first recorded in the plankton on 30 July, when the surface water temperature rose to 13.5 °C, near the Island UlkoTammio with a density of 60 ind • m-3 (Fig. 2). In comparison, we can note that in summer 1999 the same water temperature occurred mu ...
BAY-DELTA HEARINGS
... both long- and short-term elements. The recommended elements of the short-term program are based on the recognized need to provide additional protections to reduce mortality and improve overall habitat conditions for Bay-Delta fish populations while also recognizing competing demands for limited ava ...
... both long- and short-term elements. The recommended elements of the short-term program are based on the recognized need to provide additional protections to reduce mortality and improve overall habitat conditions for Bay-Delta fish populations while also recognizing competing demands for limited ava ...
Bacterivory of metazooplankton, ciliates and flagellates in a newly
... Heterotrophic bacteria form a large proportion of the biomass in pelagic ecosystems (Cho and Azam, 1988; Simon et al., 1992). The small variations in bacterial abundance, despite the fact that bacterial generation times are of the order of a day in temperate regions (Pace, 1988), suggest that there ...
... Heterotrophic bacteria form a large proportion of the biomass in pelagic ecosystems (Cho and Azam, 1988; Simon et al., 1992). The small variations in bacterial abundance, despite the fact that bacterial generation times are of the order of a day in temperate regions (Pace, 1988), suggest that there ...
Ecology of the San Francisco Estuary
The San Francisco Estuary together with the Sacramento-San Joaquin River Delta represents a highly altered ecosystem. The region has been heavily re-engineered to accommodate the needs of water delivery, shipping, agriculture, and most recently, suburban development. These needs have wrought direct changes in the movement of water and the nature of the landscape, and indirect changes from the introduction of non-native species. New species have altered the architecture of the food web as surely as levees have altered the landscape of islands and channels that form the complex system known as the Delta.This article deals particularly with the ecology of the low salinity zone (LSZ) of the estuary. Reconstructing a historic food web for the LSZ is difficult for a number of reasons. First, there is no clear record of the species that historically have occupied the estuary. Second, the San Francisco Estuary and Delta have been in geologic and hydrologic transition for most of their 10,000 year history, and so describing the ""natural"" condition of the estuary is much like ""hitting a moving target"". Climate change, hydrologic engineering, shifting water needs, and newly introduced species will continue to alter the food web configuration of the estuary. This model provides a snapshot of the current state, with notes about recent changes or species introductions that have altered the configuration of the food web. Understanding the dynamics of the current food web may prove useful for restoration efforts to improve the functioning and species diversity of the estuary.