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Dennis R. Devries - One of the best experts on this subject based on the ideXlab platform.
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effect of detritus quality on growth and survival of Gizzard shad dorosoma cepedianum potential importance to benthic pelagic coupling
Canadian Journal of Fisheries and Aquatic Sciences, 2007Co-Authors: Gene W Kim, John M Dettmers, Roy A Stein, Alpa P Wintzer, Trisha K Menker, Russell A Wright, Dennis R. DevriesAbstract:Gizzard shad (Dorosoma cepedianum) population characteristics vary with lake productivity, competing with and providing prey for sport fishes. Because age-0 Gizzard shad (>30 mm total length) are facultative detritivores, they can link benthic energy, carbon, and nutrients to pelagic food webs. To determine how age-0 Gizzard shad success varies along a detritus-quality gradient, we completed a 15-day laboratory experiment in which age-0 Gizzard shad fed lake sediment and starved Gizzard shad both suffered high mortality, whereas fish fed zooplankton grew and survived well. This suggested that detritus alone is insufficient to ensure Gizzard shad growth and survival. When sediment quality was high in outdoor mesocosms, density-dependent factors led to rapid growth only at low fish density and high-quality sediments; however, survival generally increased with sediment quality, regardless of Gizzard shad density. In four small reservoirs, annual growth of Gizzard shad increased with sediment quality. Collect...
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quantifying responses to hybrid striped bass predation across multiple trophic levels implications for reservoir biomanipulation
Transactions of The American Fisheries Society, 1996Co-Authors: John M Dettmers, Dennis R. DevriesAbstract:Abstract Top-down effects from piscivores to phytoplankton have been documented in north temperate lakes, thus permitting managers to regulate these food webs. From our review of the literature, reservoir trophic interactions appear less amenable to biomanipulation owing to the presence of a fast-growing, omnivorous planktivore, Gizzard shad Dorosoma cepedianum. If reservoir zooplankton can be enhanced by reducing Gizzard shad through biomanipulation, this could increase survival of food-limited early life stages of sport fishes dependent on zooplankton and could improve water clarity by reducing phytoplankton. To quantify this potential, we evaluated responses of age-0 Gizzard shad, crustacean zooplankton, and phytoplankton to the addition of hybrid striped bass Morone saxatilis × M. chrysops (22 kg/ha) to four of eight 0.4-ha ponds. Hybrid striped bass nearly eliminated age-0 Gizzard shad from ponds within 10 d after being stocked, which permitted zooplankton density and size to increase but had no effe...
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food web regulation by a planktivore exploring the generality of the trophic cascade hypothesis
Canadian Journal of Fisheries and Aquatic Sciences, 1995Co-Authors: Dennis R. Devries, John M DettmersAbstract:The trophic cascade hypothesis currently being tested in north temperate systems may not apply to open-water communities in lower latitude U.S. reservoirs. These reservoir communities differ dramatically from northern lakes in that an open-water omnivore, Gizzard shad (Dorosoma cepedianum), often occurs in abundance. Neither controlled by fish predators (owing to high fecundity and low vulnerability) nor by their zooplankton prey (following the midsummer zooplankton decline, Gizzard shad consume detritus and phytoplankton), Gizzard shad regulate community composition rather than being regulated by top-down or bottom-up forces. In experiments across a range of spatial scales (enclosures, 1–9 m2; ponds, 4–5 ha; and reservoirs, 50–100 ha), we evaluated the generality of the trophic cascade hypothesis by assessing its conceptual strength in reservoir food webs. We reviewed the role of Gizzard shad in controlling zooplankton populations and hence recruitment of bluegill, Lepomis macrochirus (via exploitative c...
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complex interactions between fish and zooplankton quantifying the role of an open water planktivore
Canadian Journal of Fisheries and Aquatic Sciences, 1992Co-Authors: Dennis R. DevriesAbstract:An open-water planktivore, the Gizzard shad (Dorosoma cepedianum), can drive complex interactions among fish and zooplankton in Ohio reservoirs. In Kokosing Lake, crustacean zooplankton density declined to near zero immediately after larval Gizzard shad abundance peaked during 1987 and 1988. This decline can be attributed to increased death rates, due to predation, and to reduced number of eggs per cladoceran. In an enclosure/exclosure experiment, young-of-year Gizzard shad at lake densities significantly reduced density of crustacean zooplankton and rotifers within 2 wk. In addition, phytoplankton that were edible to zooplankton were reduced in enclosures, likely due to a combination of direct herbivory by Gizzard shad and reduced nutrient availability due to uptake by the growing Gizzard shad. Gizzard shad not only directly influenced zooplankton via predation, they also indirectly affected zooplankton by reducing phytoplankton abundance. Because larval bluegill (Lepomis macrochira) migrated to the limn...
Kimberley J Mathot - One of the best experts on this subject based on the ideXlab platform.
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evolutionary design of a flexible seasonally migratory avian phenotype why trade Gizzard mass against pectoral muscle mass
Proceedings of The Royal Society B: Biological Sciences, 2019Co-Authors: Anne Dekinga, Kimberley J Mathot, Joseph B Burant, Petra Manche, Darren SaintongeAbstract:Migratory birds undergo impressive body remodelling over the course of an annual cycle. Prior to long-distance flights, red knots ( Calidris canutus islandica) reduce Gizzard mass while increasing body mass and pectoral muscle mass. Although body mass and pectoral muscle mass are functionally linked via their joint effects on flight performance, Gizzard and pectoral muscle mass are thought to be independently regulated. Current hypotheses for observed negative within-individual covariation between Gizzard and pectoral muscle mass in free-living knots are based on a common factor (e.g. migration) simultaneously affecting both traits, and/or protein limitation forcing allocation decisions. We used diet manipulations to generate within-individual variation in Gizzard mass and test for independence between Gizzard and pectoral muscle mass within individuals outside the period of migration and under conditions of high protein availability. Contrary to our prediction, we observed a negative within-individual covariation between Gizzard and pectoral muscle mass. We discuss this result as a potential outcome of an evolved mechanism underlying body remodelling associated with migration. Although our proposed mechanism requires empirical testing, this study echoes earlier calls for greater integration of studies of function and mechanism, and in particular, the need for more explicit consideration of the evolution of mechanisms underlying phenotypic design.
John M Dettmers - One of the best experts on this subject based on the ideXlab platform.
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effect of detritus quality on growth and survival of Gizzard shad dorosoma cepedianum potential importance to benthic pelagic coupling
Canadian Journal of Fisheries and Aquatic Sciences, 2007Co-Authors: Gene W Kim, John M Dettmers, Roy A Stein, Alpa P Wintzer, Trisha K Menker, Russell A Wright, Dennis R. DevriesAbstract:Gizzard shad (Dorosoma cepedianum) population characteristics vary with lake productivity, competing with and providing prey for sport fishes. Because age-0 Gizzard shad (>30 mm total length) are facultative detritivores, they can link benthic energy, carbon, and nutrients to pelagic food webs. To determine how age-0 Gizzard shad success varies along a detritus-quality gradient, we completed a 15-day laboratory experiment in which age-0 Gizzard shad fed lake sediment and starved Gizzard shad both suffered high mortality, whereas fish fed zooplankton grew and survived well. This suggested that detritus alone is insufficient to ensure Gizzard shad growth and survival. When sediment quality was high in outdoor mesocosms, density-dependent factors led to rapid growth only at low fish density and high-quality sediments; however, survival generally increased with sediment quality, regardless of Gizzard shad density. In four small reservoirs, annual growth of Gizzard shad increased with sediment quality. Collect...
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feeding preferences of omnivorous Gizzard shad as influenced by fish size and zooplankton density
Transactions of The American Fisheries Society, 1996Co-Authors: Lisa A Yako, John M DettmersAbstract:Abstract In Ohio reservoirs, larval Gizzard shad Dorosoma cepedianum less than 30 mm total length consume only zooplankton but frequently switch to detritus as they grow longer than 30 mm. However, in laboratory studies without detritus, Gizzard shad longer than 30 mm consume crustacean zooplankton. To explore the composition of diets of omnivorous 30–100-mm Gizzard shad, we completed 1-h laboratory feeding trials with different amounts of zooplankton and detritus and quantified the diets of Gizzard shad in reservoirs. In both laboratory and field, Gizzard shad ate primarily detritus but also ate zooplankton, consuming more as more became available, which demonstrates that this species is a facultative detritivore. In the field, zooplankton consumption declined as Gizzard shad body size increased. We believe Gizzard shad maximize growth by supplementing their low-protein detritus diet with more zooplankton as more becomes available. With this strategy, omnivorous Gizzard shad may compromise the potential ...
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quantifying responses to hybrid striped bass predation across multiple trophic levels implications for reservoir biomanipulation
Transactions of The American Fisheries Society, 1996Co-Authors: John M Dettmers, Dennis R. DevriesAbstract:Abstract Top-down effects from piscivores to phytoplankton have been documented in north temperate lakes, thus permitting managers to regulate these food webs. From our review of the literature, reservoir trophic interactions appear less amenable to biomanipulation owing to the presence of a fast-growing, omnivorous planktivore, Gizzard shad Dorosoma cepedianum. If reservoir zooplankton can be enhanced by reducing Gizzard shad through biomanipulation, this could increase survival of food-limited early life stages of sport fishes dependent on zooplankton and could improve water clarity by reducing phytoplankton. To quantify this potential, we evaluated responses of age-0 Gizzard shad, crustacean zooplankton, and phytoplankton to the addition of hybrid striped bass Morone saxatilis × M. chrysops (22 kg/ha) to four of eight 0.4-ha ponds. Hybrid striped bass nearly eliminated age-0 Gizzard shad from ponds within 10 d after being stocked, which permitted zooplankton density and size to increase but had no effe...
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food web regulation by a planktivore exploring the generality of the trophic cascade hypothesis
Canadian Journal of Fisheries and Aquatic Sciences, 1995Co-Authors: Dennis R. Devries, John M DettmersAbstract:The trophic cascade hypothesis currently being tested in north temperate systems may not apply to open-water communities in lower latitude U.S. reservoirs. These reservoir communities differ dramatically from northern lakes in that an open-water omnivore, Gizzard shad (Dorosoma cepedianum), often occurs in abundance. Neither controlled by fish predators (owing to high fecundity and low vulnerability) nor by their zooplankton prey (following the midsummer zooplankton decline, Gizzard shad consume detritus and phytoplankton), Gizzard shad regulate community composition rather than being regulated by top-down or bottom-up forces. In experiments across a range of spatial scales (enclosures, 1–9 m2; ponds, 4–5 ha; and reservoirs, 50–100 ha), we evaluated the generality of the trophic cascade hypothesis by assessing its conceptual strength in reservoir food webs. We reviewed the role of Gizzard shad in controlling zooplankton populations and hence recruitment of bluegill, Lepomis macrochirus (via exploitative c...
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food consumption by larval Gizzard shad zooplankton effects and implications for reservoir communities
Transactions of The American Fisheries Society, 1992Co-Authors: John M DettmersAbstract:Abstract Because peak abundance of larval Gizzard shad Dorosoma cepedianum occurs simultaneously with the midsummer decline of macrozooplankton in Ohio reservoirs, we hypothesized that zooplanktivory by larval Gizzard shad caused this decline. To test this hypothesis, we compared larval food consumption with zooplankton productivity in two reservoirs. Larval Gizzard shad began to influence zooplankton production in a reservoir with high zooplankton productivity (exceeding 125 mg·m−3·d−1) only after peak zooplankton biomass occurred, even at high larval densities (38 shad·m−3). However, consumption by early juvenile (25−30-mm) Gizzard shad severely reduced zooplankton in this reservoir. Conversely, relatively low densities of larval Gizzard shad (3–7 shad·m−3) had variable effects on zooplankton in a reservoir with low zooplankton productivity (at most 4 mg·m−3·d−1). Depending on larval Gizzard shad density and zooplankton production, larval Gizzard shad alone or in conjunction with early juveniles may con...
Anne Dekinga - One of the best experts on this subject based on the ideXlab platform.
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evolutionary design of a flexible seasonally migratory avian phenotype why trade Gizzard mass against pectoral muscle mass
Proceedings of The Royal Society B: Biological Sciences, 2019Co-Authors: Anne Dekinga, Kimberley J Mathot, Joseph B Burant, Petra Manche, Darren SaintongeAbstract:Migratory birds undergo impressive body remodelling over the course of an annual cycle. Prior to long-distance flights, red knots ( Calidris canutus islandica) reduce Gizzard mass while increasing body mass and pectoral muscle mass. Although body mass and pectoral muscle mass are functionally linked via their joint effects on flight performance, Gizzard and pectoral muscle mass are thought to be independently regulated. Current hypotheses for observed negative within-individual covariation between Gizzard and pectoral muscle mass in free-living knots are based on a common factor (e.g. migration) simultaneously affecting both traits, and/or protein limitation forcing allocation decisions. We used diet manipulations to generate within-individual variation in Gizzard mass and test for independence between Gizzard and pectoral muscle mass within individuals outside the period of migration and under conditions of high protein availability. Contrary to our prediction, we observed a negative within-individual covariation between Gizzard and pectoral muscle mass. We discuss this result as a potential outcome of an evolved mechanism underlying body remodelling associated with migration. Although our proposed mechanism requires empirical testing, this study echoes earlier calls for greater integration of studies of function and mechanism, and in particular, the need for more explicit consideration of the evolution of mechanisms underlying phenotypic design.
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digestive organ size and behavior of red knots calidris canutus indicate the quality of their benthic food stocks
Israel Journal of Ecology & Evolution, 2007Co-Authors: Jan A Van Gils, Anne Dekinga, Piet J Van Den Hout, Bernard SpaansAbstract:Assuming that animals respond optimally to environmental changes, both behavior and physiology should be useful indicators of the way that animals perceive the quality of their environment. For verification, we examined foraging time and Gizzard size of the red knot (Calidris canutus), a long-distance migrant shorebird that ingests hard-shelled mollusk prey whole and therefore readily faces digestive constraints. Nevertheless, even when digestively bottlenecked, knots can still enhance their daily energy intake by flexibly increasing the size of their digestive system, notably the Gizzard, and/or by feeding longer per day. Whether such adjustments are actually necessary depends on the quality (condition) of their food, i.e., the ratio of flesh to shell mass. Hence, Gizzard mass and daily foraging time in knots may be reliable indicators of the quality of their invertebrate prey. This idea is explored by using field data on radio-marked knots during late summer in the Dutch Wadden Sea. Their Gizzards were measured using ultrasonography and the knots' movements and working hours were monitored using handheld receivers and automated radio-tracking systems. Indeed, Gizzard mass alone predicted annual variation in food quality satisfactorily; however, adding estimates for daily foraging time significantly improved the predictions. We discuss and conceptualize how knots may trade off digestive organ size against foraging time upon arrival in the Wadden Sea, given the quality and quantity of the food on offer, and why these findings are relevant in the context of conservation of migration systems.
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modelling phenotypic flexibility an optimality analysis of Gizzard size in red knots calidris canutus
Ardea, 2006Co-Authors: Jan A Van Gils, Anne Dekinga, Phil F BattleyAbstract:Reversible phenotypic changes, such as those observed in nutritional organs of long-distance migrants, increasingly receive the attention of ornithologists. In this paper we review the cost-benefit studies that have been performed on the flexible Gizzard of Red Knots Calidris canutus. By varying the hardness of the diet on offer Gizzard mass could experimentally be manipulated, which allowed quantification of the energetic costs and benefits as a function of Gizzard size. These functions were used to construct an optimality model of Gizzard mass for Red Knots on migration and during winter. Two possible currencies were assumed, one in which Knots aim to balance their energy budget on a daily basis (satisficers), and one in which Knots aim to maximise their daily energy budget (net rate maximisers). The model accurately predicted variation in Gizzard mass that we observed (1) between years, (2) within years, and (3) between sites. Knots maintained satisficing Gizzards during winter and rate-maximising Gizzards when fuelling for migration. The model-exercise revealed the importance of digestive constraints and quality of prey in the life of Knots.
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digestive bottleneck affects foraging decisions in red knots calidris canutus ii patch choice and length of working day
Journal of Animal Ecology, 2005Co-Authors: Jan A Van Gils, Anne Dekinga, Bernard Spaans, Wouter K VahlAbstract:Summary 1. When prey occur at high densities, energy assimilation rates are generally constrained by rates of digestion rather than by rates of collection (i.e. search and handle). As predators usually select patches containing high prey densities, rates of digestion will play an important role in the foraging ecology of a species. 2. The red knot Calidris canutus shows tremendous inter- and intra-individual variation in maximum rates of digestion due to variation in the size of the processing machinery (Gizzard and intestine), which makes it a suitable species to study the effects of digestive processing rate on foraging decisions. 3. Here we report on patch use, prey choice, and daily foraging times as a function of Gizzard size in free-ranging, radio-marked, red knots. As knots crush their bulky bivalve prey in their Gizzard, the size of this organ, which we measured using ultrasonography, determines digestive processing rate. 4. Using the digestive rate model, we a priori modelled patch use, prey choice, and daily foraging times as a function of Gizzard mass. Focusing on two contrasting patches, birds with small Gizzards were expected to feed on high-quality (soft-bodied) prey found in low densities in the one patch, while birds with large Gizzards were expected to feed on low-quality (hard-shelled) prey found in high densities in the other patch. Assuming that red knots aim to balance their energy budget on a daily basis, we expected daily foraging time to decline with Gizzard mass. 5. Observed patch and prey choices were in quantitative agreement with these theoretical predictions. Observed daily foraging times were only in qualitative agreement: they declined with Gizzard mass but less steeply than predicted. 6. We discuss that red knots might be aiming for a slightly positive energy budget in order to (i) refuel their stores depleted during migration, and (ii) to insure against unpredictability in supply and demand during winter. Red knots arriving from their breeding grounds with small Gizzards are only able to realize this aim when densities of soft-bodied prey are high, which is the case in late July and early August. Rapidly declining soft-bodied prey densities throughout late summer pose a major penalty for individuals arriving late at their wintering grounds. 7. The long daily foraging periods required by knots with small Gizzards are only feasible through ‘tide-extension’. In our study area, birds can and do raise the daily low tide period from 12 h to almost 17 h by moving along with the tide in an easterly direction, subsequently flying back to their starting point at the high tide roost.
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cost benefit analysis of mollusc eating in a shorebird ii optimizing Gizzard size in the face of seasonal demands
The Journal of Experimental Biology, 2003Co-Authors: Jan A Van Gils, Anne Dekinga, Theunis Piersma, Maurine W DietzAbstract:Aiming to interpret functionally the large variation in Gizzard masses of red knots Calidris canutus, we experimentally studied how the digestive processing rate is influenced by the size of the Gizzard. During their non-breeding season, red knots feed on hard-shelled molluscs, which they ingest whole and crush in their Gizzard. In three experiments with captive birds we tested predictions of the hypothesis that Gizzard size, via the rate of shell crushing and processing, constrains intake rate in red knots (against the alternative idea that external handling times constrain intake rate). Gizzard size within individual birds was manipulated by varying the hardness of the diet on offer, and was confirmed by ultrasonography. The results upheld the 'shell-crushing hypothesis' and rejected the 'handling time hypothesis'. Intake rates on with-shell prey increased with Gizzard size, and decreased with shell mass per prey. Intake rates on soft (without shell) prey were higher than on with-shell prey and were unaffected by Gizzard size. Offering prey that were heavily shelled relative to their flesh mass led to energy intake rates that were marginally sufficient to balance the daily energy budget within the time that is naturally available in a tidal system. We predicted the optimal Gizzard sizes that are required to either (1) balance energy income with energy expenditure, or (2) to maximise net daily energy intake. The Gizzard mass of free-living red knots in the Wadden Sea is such that it maximises daily net energy intake in spring when fuelling for migration, while it balances energy budget throughout the remainder of the year.
Darren Saintonge - One of the best experts on this subject based on the ideXlab platform.
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evolutionary design of a flexible seasonally migratory avian phenotype why trade Gizzard mass against pectoral muscle mass
Proceedings of The Royal Society B: Biological Sciences, 2019Co-Authors: Anne Dekinga, Kimberley J Mathot, Joseph B Burant, Petra Manche, Darren SaintongeAbstract:Migratory birds undergo impressive body remodelling over the course of an annual cycle. Prior to long-distance flights, red knots ( Calidris canutus islandica) reduce Gizzard mass while increasing body mass and pectoral muscle mass. Although body mass and pectoral muscle mass are functionally linked via their joint effects on flight performance, Gizzard and pectoral muscle mass are thought to be independently regulated. Current hypotheses for observed negative within-individual covariation between Gizzard and pectoral muscle mass in free-living knots are based on a common factor (e.g. migration) simultaneously affecting both traits, and/or protein limitation forcing allocation decisions. We used diet manipulations to generate within-individual variation in Gizzard mass and test for independence between Gizzard and pectoral muscle mass within individuals outside the period of migration and under conditions of high protein availability. Contrary to our prediction, we observed a negative within-individual covariation between Gizzard and pectoral muscle mass. We discuss this result as a potential outcome of an evolved mechanism underlying body remodelling associated with migration. Although our proposed mechanism requires empirical testing, this study echoes earlier calls for greater integration of studies of function and mechanism, and in particular, the need for more explicit consideration of the evolution of mechanisms underlying phenotypic design.