Captive sentinel hosts efficiently measure the establishment,seasonality and dispersal of a parasitoid biological control agent     

Hardwick  Scott  Phillips  Craig B. 《Journal of pest science》2021,94(3):817-827

Introduced biological control agents are used to suppress populations and reduce the damage caused by many exotic herbivorous insects in New Zealand pasture. Understanding the dispersal behaviour of a recently introduced biocontrol agent in its new environment is important as it helps biocontrol practitioners make decisions on the number and location of future releases. In this study, a monitoring device which contained sentinel hosts was developed to monitor the establishment and dispersal of the Irish strain of Microctonus aethiopoides (Hymenoptera, Braconidae) into areas of the South Island of New Zealand where the clover pest Sitona obsoletus Gmelin (Coleoptera, Curculionidae) had recently become established. Field tests of the monitoring device at five sites in Marlborough confirmed that M. aethiopoides would enter the device through a 900 µm mesh and parasitise the sentinel weevils within. In a further trial conducted over 4 years at four sites in North Canterbury, monitoring devices successfully tracked the dispersal and establishment of M. aethiopoides at sites up to 27 km from the original release site. Monitoring devices containing sentinel hosts may help reduce the cost of classical biological control programmes as they enable rapid sampling of numerous sites and largely eliminate the time consuming practice of dissecting field collected hosts to determine the presence of the parasitoid.

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A partial-reuse system for coldwater aquaculture   总被引：7，自引：0，他引：7  

Steven T. Summerfelt  John W. Davidson  Thomas B. Waldrop  Scott M. Tsukuda  Julie Bebak-Williams 《Aquacultural Engineering》2004,31(3-4):157-181

A model partial-reuse system is described that provides an alternative to salmonid production in serial-reuse raceway systems and has potential application in other fish-culture situations. The partial-reuse system contained three 10 m³ circular ‘Cornell-type’ dual-drain culture tanks. The side-wall discharge from the culture tanks was treated across a microscreen drum filter, then the water was pumped to the head of the system where dissolved carbon dioxide (CO₂) stripping and pure oxygen (O₂) supplementation took place before the water returned to the culture tanks. Dilution with make-up water controlled accumulations of total ammonia nitrogen (TAN). An automatic pH control system that modulated the stripping column fan ‘on’ and ‘off’ was used to limit the fractions of CO₂ and unionized ammonia nitrogen (NH₃---N). The partial-reuse system was evaluated during the culture of eight separate cohorts of advanced fingerlings, i.e., Arctic char, rainbow trout, and an all female brook trout × Arctic char hybrid. The fish performed well, even under intensive conditions, which were indicated by dissolved O₂ consumption across the culture tank that went as high as 13 mg/L and fish-culture densities that were often between 100 and 148 kg/m³. Over all cohorts, feed conversion rates ranged from 1.0 to 1.3, specific growth rates (SGR) ranged from 1.32 to 2.45% body weight per day, and thermal growth coefficients ranged from 0.00132 to 0.00218. The partial-reuse system maintained safe water quality in all cases except for the first cohort—when the stripping column fan failed. The ‘Cornell-type’ dual-drain tank was found to rapidly (within only 1–2 min) and gently concentrate and flush approximately 68–88% (79% overall average) of the TSS produced daily within only 12–18% of the tank’s total water flow. Mean TSS concentrations discharged through the three culture tanks’ bottom-center drains (average of 17.1 mg/L) was 8.7 times greater than the TSS concentration discharged through the three culture tanks’ side-wall drains (average of 2.2 mg/L). Overall, approximately 82% of the TSS produced in the partial-reuse system was captured in an off-line settling tank, which is better TSS removal than others have estimated for serial-reuse systems (approximately 25–50%). For the two cohorts of rainbow trout, the partial-reuse system sustained a production level of 35–45 kg per year of fish for every 1 L/min of make-up water, which is approximately six to seven times greater than the typical 6 kg per year of trout produced for every 1 L/min of water in Idaho serial-reuse raceway systems.  相似文献   

Foraging Behavior and Monetary Impact of Wading Birds at Arkansas Baitfish Farms   总被引：1，自引：0，他引：1  

Scott J.  Werner J. Brent  Harrel David E.  Wooten 《Journal of the World Aquaculture Society》2005,36(3):354-362

Abstract— We conducted foraging observations, food habits studies, and producer surveys to determine the foraging behavior and monetary impact of great blue herons Ardea herodas , great egrets A. alba , and little blue herons Egrerra caerulea foraging at Arkansas baiffish farms. Although great egrets captured most baitfish/minute, captures/strike were nearly identical among the three wading bird species. American gizzard shad Dorosoma cepedianum , goldfish Carassius auratus , and giant water bugs Hemiptera: Belostomatidae were collected from the gastro-intestinal tract of great blue herons. Only golden shiners Noremgonus crysoleucas and goldfish were found in great egrets. We found dragonflies Odonata , golden shiners, green sunfish Lepomis cyanellus , and water bugs in little blue herons. In contrast to other birds collected, snowy egrets E. thula were found to contain mosquito fish Gambusia affinis . Among 2,742 teleost otoliths recovered from collected great blue herons, great egrets, and little blue herons, most otoliths belonged to the Cyprinidae family (including the baiffishes). Surveyed farm managers use various auditory and visual stimuli to disperse fish-eating birds from their farms. Surveyed baitfish farmers suggested that the average cost of their annual bird harassment program was $11,580 at relatively small farms (< 202 ha) and $104,560 at relatively large × 202 ha) baitfish aquaculture facilities. We estimated the replacement cost of baitfish consumed by wading buds based upon their daily food requirements, the food habits of herons and egrets at baiffish farms, the hypothetical abundance of wading birds at a particular baitfish farm (relative to survey results), the duration of herons and egrets reported by farm managers, and current baitfish market values.  相似文献   

SHORT COMMUNICATION: Group ‘resting’ behaviour in a population of captive bull huss (Scyliorhinus stellaris)     

G.W. Scott  K. Gibbs  J. Holding 《Aquarium Sciences and Conservation》1997,1(4):251-254

Captive bull huss, Scyliorhinus stellaris (L.), rest in groups more often than alone. These groups are of fluid composition, suggesting that there is no special need to maintain group membership when translocating animals.This revised version was published online in October 2005 with corrections to the Cover Date.  相似文献   

Reproductive performance of common dentex, Dentex dentex, broodstock held under different photoperiod and constant temperature conditions     

M. Pavlidis  S. Keravec  L. Greenwood  B. Mourot  A.P. Scott 《Fish physiology and biochemistry》2001,25(3):171-180

The effect of photoperiod and temperature on the timing and the quality of spawning, and on associated endocrine changes in circulating 17β-oestradiol, 11-ketotestoserone (11-KT) and vitellogenin (Vtg) were investigated in common dentex, Dentex dentex, undergoing their second reproductive cycle. The possibility was also explored of using the measurement of steroids in the culture water of broodstock tanks, rather than in individual blood plasma samples, as a potentially useful tool for assessing the physiological state of a fish without disturbing them. One group of fish was exposed to a simulated natural seasonal cycle and ambient temperature (CONTROL). The other two groups were exposed to simulated seasonal photoperiod cycles (12 month-long) but which were phase-shifted either three months before (ADVANCED) or after (DELAYED) the natural cycle. Temperature was kept at 19.4±0.9 °C all-year-round. In the CONTROL, spawning started in mid-April and lasted until mid-June, while in the ADVANCED group, spawning started 4 months earlier and in the DELAYED group 2 months later than the CONTROL. The total egg production, egg quality, hatching rate, relative fecundity, and spawning index of the experimental groups were similar to the controls. The differences in spawning time induced by photothermal manipulation were associated with a difference in the timing of peak concentrations of plasma E₂, 11-KT and Vtg. In all three groups, the amounts of conjugated 17,20β-dihydroxy-4-pregnen-3-one (17,20β-P) and free and sulfated 11-KT which could be extracted from the water during the spawning period were significantly higher than those found in the preovulatory period. However, the differences were mostly less than 2-fold suggesting that, at least under the conditions employed in this study, the method was of limited use for non-intrusive detection of gonadogenesis and spawning (as had been hoped). The observed differences in spawning time and in the seasonal changes of sex steroids and Vtg confirm and extend the findings on marine fish. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

Population structure,genetic diversity,and colonization history of the eastern pondmussel,Sagittunio nasutus,in the Great Lakes drainage     

Mariah W. Scott  Todd J. Morris  David T. Zanatta 《水产资源保护:海洋与淡水生态系统》2020,30(4):631-646

1. The eastern pondmussel, Sagittunio nasutus (Bivalvia: Unionida), has declined in abundance and distribution in eastern North America over the last few decades. The declines are predominantly the result of infestation by invasive dreissenid mussels and changes in habitat. The species is now considered imperilled across large portions of its distribution, especially in the Laurentian Great Lakes region.
2. The genetic diversity and structure of the remnant populations in the Great Lakes region were assessed using 10 newly developed microsatellite DNA loci for S. nasutus. Understanding the remaining populations can inform future management projects and determine whether the remnant populations have experienced a genetic bottleneck or a founder effect. We hope that this will inform the conservation of other species in regions founded by, and isolated from, a more genetically diverse source population or with disjointed geographical distributions.
3. Focusing on the Great Lakes region, samples (n = 428) from 62 collection sites in 28 water bodies were collected. Across the locations sampled for S. nasutus 11 genetic populations were identified, with significant genetic differentiation among them. The genetic structure of the species was assessed, with genetic similarities among populations compared and with geographical routes of colonization and gene flow evaluated.
4. Initial colonization from the Atlantic coast into Lake Erie and Lake Ontario is evident, followed by colonization events into nearby inland rivers and lakes. Analyses found evidence of inbreeding in all but one population and evidence of past genetic bottlenecks or strong founder effects in all but four populations. This study deepens our understanding of the genetic past and present of this imperilled species, providing conservation suggestions for the future management of the species.

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Integrating physiology and life history to improve fisheries management and conservation   总被引：3，自引：0，他引：3  

Jeffery L. Young  Zosia B. Bornik  Michelle L. Marcotte  Kim N. Charlie  Glenn N. Wagner  Scott G. Hinch  & Steven J. Cooke 《Fish and Fisheries》2006,7(4):262-283

Knowledge of life‐history traits is increasingly recognized as an important criterion for effective management and conservation. Understanding the link between physiology and life history is an important component of this knowledge and in our view is particularly relevant to understanding marine and freshwater fishes. Such linkages (i.e. the life‐history/physiology nexus) have been recently advocated for avian systems and here we explore this concept for fish. This paper highlights the gap in fisheries literature with regard to understanding the relationship between physiology and life history, and proposes ways in which this integration could improve fisheries management and conservation. We use three case studies on different fishes (i.e. the Pacific salmon, the grouper complex and tuna) to explore these issues. The physiological structure and function of fish plays a central role in determining stock response to exploitation and changes in the environment. Physiological measures can provide simple indicators necessary for cost‐effective monitoring in the evaluation of fisheries sustainability. The declining state of world fisheries and the need to develop and implement restoration strategies, such as hatchery production or protected areas, provides strong incentive to better understand the influence of physiology on population and reproductive dynamics and early life history. Physiology influences key population‐level processes, particularly those dealing with reproduction, which must be incorporated into the design and successful implementation of specific and broadscale initiatives (e.g. aquatic protected areas and bycatch reduction). Suggestions are made for how to encourage wider application of the physiology/life‐history link, in fisheries management and conservation, as well as more broadly in education and research.  相似文献   

Chemical pollution as a factor affecting the sea survival of Atlantic salmon, Salmo salar L.     

D. Scott 《Fisheries Management and Ecology》2001,8(6):487-499

The catch of Atlantic salmon Salmo salar L., from ocean and coastal fisheries since 1960 is described and the decline starting in 1973 noted. This decline continued despite cessation of some fisheries, and evidence indicates a marine locus for the decline. Oceanic pollution has received little attention, and ozone loss has caused an increase in UV radiation reaching the surface of the North Atlantic. Direct effects of this increase include negative impacts on the food chain. Photo-induced toxicity of polycyclic aromatic hydrocarbons (PAH) is a possible effect, but concentrations of these compounds in oceanic waters are low. Chlorinated organic compounds are widely distributed in the North Atlantic, and their persistence, lipophilicity, bioaccumulation potential and toxicity represent a potential hazard to salmon. The suggested causes of decline are likely to be complementary rather than exclusive.  相似文献   

Phosphorus fractionation and mobility in Loch Leven sediments     

J. G. Farmer  A. E. Bailey-Watts  A. Kirika  C. Scott 《水产资源保护:海洋与淡水生态系统》1994,4(1):45-56

This paper reports on the application of a chemical fractionation scheme for assessing the amounts, forms and potential mobility (recycling potential) of phosphorus in the sediments of the freshwater Loch Leven, which is currently highly topical in relation to eutrophication and its manifest dense, potentially toxic, blue-green algae. The findings are placed in the context of the biological importance of the loch, the problems it is experiencing and some management options for its restoration. The fractionation scheme adopted enabled quantification of phosphorus in sediment pore water and in sedimentary solid phases classified as ‘loosely-bound’, ‘reductant-soluble’, ‘oxide-adsorbed’, ‘organic’, ‘apatite-bound’ and ‘residual’ in the sections of a 16-cm core collected in January 1990. Vertical profiles of reductant-soluble and pore water phosphorus and iron show redox-controlled remobilization and cycling within the sediment to be the principal mechanisms leading to the surface sediment enrichment of phosphorus observed during the winter months. The association of phosphorus with iron oxyhydroxides in the reductant-soluble fraction, which accounts for 31% of the total phosphorus (2470 mg kg^?1) in the 0–1 cm section compared with 0.5% loosely-bound, 25.6% oxide-adsorbed, 27.9% organic, 9.9% apatite-bound and 5.1% residual, restricts the release of phosphorus to the overlying water column in winter. Extrapolation of the data to the whole loch suggests that in early 1990 more than 40 tonnes of phosphorus were associated with the surfaces of iron oxyhydroxides in the upper 10 cm of Loch Leven sediment, about five times that required to raise loch water concentrations to maxima of 0.15 mg L^?1 observed during the algal blooms of summer under conditions favourable to the release of phosphorus from the sediments. Despite recent measures to reduce external inputs of phosphorus and thereby limit the degree of eutrophication of Loch Leven, there appears to have been little overall change in the inventory of phosphorus associated with iron in the upper 10 cm of sediment since 1970. There should be more detailed seasonal and spatial studies of the chemical fractionation and mobility of phosphorus in Loch Leven sediments to investigate the extent to which release from the reductant-soluble iron oxyhydroxide fraction (internal loading) contributes to the highly elevated phosphorus concentrations in loch water during summer.  相似文献   

Ten-year response of bird communities to an operational herbicide-shelterwood treatment in a northern hardwood forest     

Scott H. Stoleson  Stephen B. Horsley 《Forest Ecology and Management》2011,262(7):1205-1214

Use of herbicides in forestry to direct successional trajectories has raised concerns over possible direct or indirect effects on non-target organisms. We studied the response of forest birds to an operational application of glyphosate and sulfometuron methyl herbicides, using a randomized block design in which half of each 8 ha block received herbicide and the other acted as a control, on shelterwood seed-cut Allegheny hardwood stands in northwestern Pennsylvania. We monitored birds using 50 m radius point counts in two pretreatment years and for 10 years post-treatment (1992-2004). Fences were erected six years after herbicide treatment in response to increased deer browsing at a subset of sites. Avian responses to herbicide treatment varied by nesting guild: we detected no response by cavity-nesters, but documented declines in the shrub-, ground- and canopy-nesting guilds. Responses were short-lived (2-4 years post-treatment), but shrub-nesters did not recover until fencing provided regenerating vegetation respite from browsing. Thus, apparent responses of birds to herbicide were confounded with deer browsing in this study. High species turnover, even within control plots, suggests that avian communities may be assessed more appropriately assessed at larger spatial scales than those used in this study (6.5-8 ha).  相似文献