bluuebunny/crossref_metadata_2025 huggingface dataset:
Contribution ofBordetella bronchisepticaFilamentous Hemagglutinin and Pertactin to Respiratory Disease in Swine
Authors: Nicholson Tracy L. , Brockmeier Susan L. , Loving Crystal L.
Published: February 2009

Bordetella bronchisepticais pervasive in swine populations and plays multiple roles in respiratory disease. Most studies addressing virulence factors ofB. bronchisepticaare based on isolates derived from hosts other than pigs. Two well-studied virulence factors implicated in the adhesion process are filamentous hemagglutinin (FHA) and pertactin (PRN). We hypothesized that both FHA and PRN would serve critical roles in the adhesion process and be necessary for colonization of the swine respiratory tract. To investigate the role of FHA and PRN inBordetellapathogenesis in swine, we constructed mutants containing an in-frame deletion of the FHA or the PRN structural gene in a virulentB. bronchisepticaswine isolate. Both mutants were compared to the wild-type swine isolate for their ability to colonize and cause disease in swine. Colonization of the FHA mutant was lower than that of the wild type at all respiratory tract sites and time points examined and caused limited to no disease. In contrast, the PRN mutant caused similar disease severity relative to the wild type; however, colonization of the PRN mutant was reduced relative to the wild type during early and late infection and induced higher anti-Bordetellaantibody titers. Together, our results indicate that despite inducing different pathologies and antibody responses, both FHA and PRN are necessary for optimal colonization of the swine respiratory tract.
Asc and Ipaf Inflammasomes Direct Distinct Pathways for Caspase-1 Activation in Response to
Legionella pneumophila
Authors: Case Christopher L. , Shin Sunny , Roy Craig R.
Published: February 2009

Caspase-1 activation is a key feature of the innate immune response of macrophages elicited by pathogens and a variety of toxins. Here, we determined the requirement for different adapter proteins involved in regulating host processes mediated by caspase-1 after macrophage infection by
Legionella pneumophila
. The adapter protein Asc was found to be important for caspase-1 activation during
L. pneumophila
infection. Activation of caspase-1 through Asc did not require the flagellin-sensing pathway involving the host nucleotide-binding domain and leucine-rich repeat-containing protein Ipaf (NLRC4). Asc-dependent caspase-1 activation was inhibited by high extracellular potassium levels, whereas Ipaf-dependent activation was unaffected by potassium treatment. Activation of caspase-1 in macrophages occurred independently of Nalp3 and proteasome activity, suggesting that a previously uncharacterized mechanism for caspase-1 activation through Asc may be triggered by
L. pneumophila
. Rapid pore formation and pyroptosis induced by
L. pneumophila
required caspase-1, Ipaf, and bacterial flagellin but occurred independently of Asc. Equivalent levels of active interleukin-18 (IL-18) were detected in the lungs of mice infected with a flagellin-deficient strain of
L. pneumophila
and Asc-deficient mice infected with wild-type
L. pneumophila
. Active IL-18 was undetectable in the lungs of Asc-deficient mice infected with an
L. pneumophila
flagellin mutant, indicating independent roles for Ipaf and Asc in caspase-1-mediated processing and release of IL-18 in vivo. Ipaf-dependent activation of caspase-1 restricted bacterial replication in vivo, whereas Asc was dispensable for restriction of
L. pneumophila
replication in mice. Thus,
L. pneumophila-
mediated caspase-1 activation involves the coordinate activities of inflammasomes differentially regulated by Ipaf and Asc.
Electrochemical characteristics of an interdigitated microband electrode array of boron-doped diamond film
Authors: Zhang Wei , Xie Shaoai , Li Mei , Chen Hongjin , Ma Li , Jia Jinping
Published: February 2009

An microband electrode array (MBEA) of a boron-doped diamond (BDD) film was prepared by using the hot-filament chemical vapor deposition (HF-CVD) technique and microfabrication process with a standard photolithography technique. Electrochemical properties of a single MBEA (S-MBEA) and interdigitated MBEA (I-MBEA) of BDD film were studied by cyclic voltammetry (CV) analysis. Charge transfer characteristics were examined by electrochemical impedance spectra (EIS) analysis. A ferri–ferrocyanide redox system was chosen to act as the probe of one-electron transfer processes. The redox reaction was controlled by linear diffusion-limited transport at S-MBEA and quasi-steady-state non-linear diffusion at I-MBEA. A relation between current limit at I-MBEA and sweep rate was obtained with a correlation coefficient greater than 0.93. Hemispherical diffusion was primary at I-MBEA of BDD surface. There were two time constants for the S-MBEA and one time constant for the I-MBEA in the redox system.
Altruistic surrogacy: the necessary objectification of surrogate mothers
Authors: Tieu M M
Published: February 2009

One of the major concerns about surrogacy is the potential harm that may be inflicted upon the surrogate mother and the child after relinquishment. Even if one were to take the liberal view that surrogacy should be presumptively allowed on the basis of autonomy and/or compassion, evidence of harm must be taken seriously. In this paper I review the evidence from psychological studies on the effect that relinquishing a child has on the surrogate mother and while it appears that many surrogates are able to cope with relinquishment, I argue that there are good reasons, grounded in empirical evidence, to support the view that the subsequent management of the relinquishment necessarily objectifies the surrogate mother.
Composition, training needs and independence of ethics review committees across Africa: are the gate-keepers rising to the emerging challenges?
Authors: Nyika A , Kilama W , Chilengi R , Tangwa G , Tindana P , Ndebele P , Ikingura J
Published: February 2009

Background:

The high disease burden of Africa, the emergence of new diseases and efforts to address the 10/90 gap have led to an unprecedented increase in health research activities in Africa. Consequently, there is an increase in the volume and complexity of protocols that ethics review committees in Africa have to review.

Methods:

With a grant from the Bill and Melinda Gates Foundation, the African Malaria Network Trust (AMANET) undertook a survey of 31 ethics review committees (ERCs) across sub-Saharan Africa as an initial step to a comprehensive capacity-strengthening programme. The number of members per committee ranged from 3 to 21, with an average of 11. Members of 10 institutional committees were all from the institution where the committees were based, raising prima facie questions as to whether independence and objectivity could be guaranteed in the review work of such committees.

Results:

The majority of the committees (92%) cited scientific design of clinical trials as the area needing the most attention in terms of training, followed by determination of risks and benefits and monitoring of research. The survey showed that 38% of the ERC members did not receive any form of training. In the light of the increasing complexity and numbers of health research studies being conducted in Africa, this deficit requires immediate attention.

Outcome:

The survey identified areas of weakness in the operations of ERCs in Africa. Consequently, AMANET is addressing the identified needs and weaknesses through a 4-year capacity-building project.
Transforming growth factor β1 signalling, wound healing and repair: a multifunctional cytokine with clinical implications for wound repair, a delicate balance
Authors: Klass B R , Grobbelaar A O , Rolfe K J
Published: February 2009

Transforming growth factor β1 (TGFβ1) is a multifunctional cytokine known to be involved in a number of human diseases. It is believed to play an important role in wound healing and repair, as it is a key regulator of the production and remodelling of the extracellular matrix through its effect on mesenchymal cells. Over the last few years, it has become evident that the signalling pathway of TGFβ is complex with numerous receptor–ligand interactions, intracellular pathways and a number of mechanisms, which not only control the signalling but may also decide the response to the TGFβ signal. This review focuses on TGFβ1 signalling and the role that TGFβ1 plays in wound healing, repair and scarring.
Current treatments in the management of patients with primary hyperparathyroidism
Authors: Iglesias P , Díez J J
Published: February 2009

Primary hyperparathyroidism (PHP) develops as a consequence of autonomous hypersecretion of parathyroid hormone (PTH) by parathyroid glands usually because of a solitary parathyroid adenoma. Parathyroidectomy, a surgical procedure with a high success rate, is currently the treatment of choice. Pathological parathyroid tissue excision can be achieved by surgical and non-surgical ablative therapy. Bilateral cervical surgical exploration performed by an experienced parathyroid surgeon is curative in 95–98% of PHP and is associated with a low complication rate. In some patients, such as those with a single parathyroid adenoma adequately localised in presurgical imaging studies, this type of surgery may be more extensive than is needed. Moreover, the introduction of new intraoperative parathyroid-localising techniques, such as intraoperative PTH measurement and nuclear mapping, has boosted the development of new and less invasive parathyroid surgical techniques. Other non-surgical ablative techniques, such as selective percutaneous ethanol injection and transcatheter ablation of pathological parathyroid tissue, may be adequate in cases in which surgery is contraindicated. Lastly, among the therapeutic alternatives to parathyroidectomy are antiresorptive drugs (bisphosphonates, oestrogens and selective oestrogen receptor modulators) and inhibitors of PTH secretion (calcimimetics). A combination of drugs with diverse mechanisms of action may have a synergistic effect in the symptomatic control of PHP.
Factors Affecting Variability of Trapnet Catches
Authors: Hamley John M. , Howley Thomas P.
Published: February 2009

We summarized the literature relating to sampling characteristics of trapnets, and examined the variability of trapnet catches from Long Point Bay, Lake Erie. In Long Point Bay the frequency distributions of numbers of fish caught per trapnet lift were very skewed, peaking at zero for all species. Standard deviations of raw catches of even the most commonly taken species (Ambloplites rupestris, Perca flavescens, Aplodinotus grunniens) were high, about twice as large as their means. From 50 to 65% of the variability of transformed catches could be attributed to differences in soak time, sampling location, season, and year. Precision of estimating abundances of fish from catch-per-effort data is low for trapnets as well as for other sampling gear. Our fishing effort of nine trapnet lifts per sampling design cell sufficed to estimate, with 95% confidence, geometric mean catches in Long Point Bay to within a factor of 2 of their true values. To estimate them to within 20–25% would have required about 100 lifts. Regarding possible future changes of abundance, it would take 3 yr of observation to establish statistical significance of a decrease of arithmetic mean catches to half the levels observed in 1971–78.
Planktivory in a Littoral-Dwelling Lake Fish Association: Prey Selection and Seasonality
Authors: Keast Allen
Published: February 2009

A littoral zone assemblage of six planktivorous fishes (Pimephales notatus, Notropis heterodon, Fundulus diaphanus, Lepomis macrochirus, Ambloplites rupestris, Perca flavescens), and five zooplankter species, was analysed relative to three hypotheses concerning prey consumption: (1) Size-dependent predation will operate, as elsewhere. (2) Small-bodied planktivores, unable to handle larger prey, will take the most abundant zooplankter and not show species specialization. (3) The strongly cyclical nature of zooplankton populations will not permit fish species to specialize exclusively on zooplankton; there will be a negative correlation between zooplankton numbers and use of alternative prey, and at this time the planktivores will minimize competition by choosing different alternative prey. The first hypothesis was supported, the second and third partially so. The small specialist planktivores, P. notatus and N. heterodon, did not take the commonest small zooplankter, Bosmina longirostris: rather, they specialized largely on Chydorus sphaericus, feeding on it even when rare. Lepomis macrochirus, a generalise took largely B. longirostris, No species was exclusively planktivorous. The species only partly differed in alternative prey types eaten. Chironomid larvae were a regular item of diet of most species.
Recruitment of the Puerulus of the Spiny Lobster, Panulirus marginatus, in Hawaii
Authors: MacDonald Craig D.
Published: February 2009

Settlement of pueruli of the Hawaiian spiny lobster, Panulirus marginatus, was monitored on a weekly to monthly basis during June 1979 – June 1985 at three islands situated across the extent of the Hawaiian Archipelago to define patterns of recruitment over the species' geographic range. Settlement occurred irregularly throughout the year at French Frigate Shoals near the center, but seasonally during reciprocal times of the year at Kure Atoll and Oahu located at opposite ends of the island chain. There were no significant long-term trends in monthly mean catch per collector. Settlement occurred primarily during the new moon and first quarter lunar phases at each island. The seasonal and geographic patterns of recruitment may be determined to a large extent by an island's position relative to the northern and southern boundaries of the North Pacific Central Water type. Seasonal changes in the position of the principal wind systems of the region, the trades and westerlies, also may influence these patterns. Settlement tended to be higher at the center of the archipelago than at either end and higher in the Northwestern Hawaiian Islands than around the main high islands. Regional differences in catch rates in the commercial fishery may be related to regional differences in puerulus recruitment. Settlement overall was low in comparison with spiny lobsters elsewhere.
Relationship Between Indices of Juvenile Abundance and Recruitment in the Western Rock Lobster (Panulirus cygnus) Fishery
Authors: Caputi N. , Brown R. S.
Published: February 2009

Indices of abundance of 3- and 4-yr-old juvenile western rock lobsters (Panulirus cygnus) were used to determine the status of the stocks between the puerulus stage and subsequent recruitment to the fishery. These indices were based on logarithmically transformed catch rate data of undersize lobsters obtained from a monitoring program which commenced in 1971–72. The juvenile indices were determined from regression coefficients associated with the factor "year", adjusted for other factors, e.g. location, month, depth, soak time, which affect juvenile catch rates. A revised index of recruitment was based on logarithmically transformed catch rates, in depths up to 18 m. A 7-d moving average was used to smooth out daily fluctuations to enable the "best" 60-d catch rate over the period of recruitment to the fishery (November–January) to be determined so that differences in the time of recruitment may be taken into account in quantifying the level of recruitment. This index is compared with a previous recruitment index based on total catch divided by total effort during November–December. The relationships between the abundance indices of 3- and 4-yr-old male juveniles and the recruitment index resulted in correlations of 0.95 and 0.93, respectively, from the log–log analyses of 11 year-classes with a multiple correlation of 0.97 when the 3- and 4-yr-old indices were used in a multiple regression. These indices provide an independent method to support or modify the prediction of recruitment based on an index of abundance of settling puerulus (aged 9–11 mo) obtained 4 yr before they recruit into the fishery.
California Spiny Lobster (Panulirus interruptus) Larval Retention and Recruitment: A Review and Synthesis
Authors: Pringle J. D.
Published: February 2009

The late Dr. M. W. Johnson studied Panulirus interruptus phyllosome larval natural history from samples collected between 1949 and 1955 inclusive on the California Cooperative Oceanic Fisheries Investigations (CalCOFI) grid. Despite wide broadcasting of larvae, he concluded that gyres and countercurrents must retain larvae to ensure recruitment to the population. The conclusions are reviewed and the data reinterpreted in light of both recent physical oceanographic information and congeneric biology. Phyllosome concentrations are highly aggregated within the California Current: 66% of the larvae were located in 12% of the areal distribution, with the concentrations located off central Baja California. Stage I larvae cooccurred nearshore in areas of moderate Ekman wind drift. They were quickly (about 13 d) transported southward, likely by the California Current, to a perennially occurring, semipermanent gyre. Phyllosome maturation to stage VIII occurred over a 5-mo period within the gyre. Late-stage (IX–XI) concentrations occurred slightly northwest of the gyre, possibly transported by the counter-flowing Davidson Current. Pueruli were rarely encountered, suggesting a deepwater (> 140 m) distribution. Onshore movement is likely made by the puerulus stage. Phyllosome concentrations in the Southern California Bight were rare (stage IV only). Evidence is presented to support the hypothesis that recruitment to this northern, relatively impoverished brood stock area may be episodic, influenced by the large-scale, interannual El Niño events.
The Pelagic Phase of Spiny Lobster Development
Authors: Phillips B. F. , McWilliam P. S.
Published: February 2009

A reappraisal of the pelagic phase of development in palinurid lobsters, in conjunction with recent oceanographic data, shows that the ontogenetic changes in the vertical migratory behaviour of phyllosoma larvae operate as a biological strategy to effect larval recruitment. Wind-driven surface currents can transport the larvae in the opposite direction to the general circulation of the upper 300 m water layer. Ocean circulation charts are unreliable indicators of likely paths of larval transport because of their gross scale, lack of seasonal information, and the absence of indications of wind-driven surface currents. The majority of larvae are transported beyond the continental shelf to areas greater than 100 km offshore. This appears to be the principal source of larval recruitment to benthic populations, although some local recruitment from coastal areas may occur. Larval transport between populations of Jasus sp. in the Southern Ocean appears likely but is unconfirmed. For some insular populations this may be the sole, or major, source of recruitment. Delayed development of phyllosomata, or of pueruli, may account for year-round settlement in some species. Salinity changes are implicated as a factor stimulating metamorphosis from the final phyllosoma larval stage. The pelagic phase is completed by the nektonic, puerulus stage which swims (possibly directionally) across the continental shelf before settling and metamorphosing into the benthic stage.
Factors Affecting Growth and Maturation of Spiny Lobsters, Panulirus argus, in the Florida Keys
Authors: Hunt John H. , Lyons William G.
Published: February 2009

Overall growth rates of sublegal-sized (50–75 mm carapace length (CL)) and large ([Formula: see text] CL) spiny lobsters, Panulirus argus, in the Florida Keys were 0.46 and 0.15 mm CL/wk; growth rates were 48 and 67% less, respectively, in winter than in summer. Injuries caused a significant 39% growth reduction in small (≤60 mm CL) lobsters. Growth decreased dramatically between 74 mm CL (0.46 mm CL/wk) and 76 mm CL (0.23 CL/wk). Between 71–75 and 76–80 mm CL size classes, intermolt periods of females increased 58% and molt increments decreased 16%; male intermolt periods increased 33% but molt increments did not change until 85 mm CL. Consequently, large ([Formula: see text] CL) males grew 33% faster than females. Changes in growth rates signified a shift in energy use at onset of maturation.
Evaluation of the Role of Nutrition in Lobster Recruitment
Authors: Castell J. D. , Kean J. C.
Published: February 2009

Many of the hypotheses and proposals presented here on the role of nutrition in lobster recruitment have been derived from research on other aquatic animals. Little research has focused on the determination of nutritional requirements of lobsters and even that has been primarily with small juveniles (36–1000 mg). Despite the tacit acknowledgement that maternal fecundity and egg viability are a function of quantity and quality of available food, little is known about the nutrition of reproductively mature lobsters. The importance of broodstock nutrition and possible methods for evaluating nutritional status are discussed. Information on protein, essential amino acids, vitamins, minerals, carbohydrates, and lipids is summarized. Additionally, some proposals for field application of nutritional response criteria used in the laboratory are discussed. Though research on larvae adult broodstock nutrition, effects of environmental factors (e.g. temperature, salinity, photoperiod, etc.), as well as many other aspects of nutrition is yet to be done, there is "good opportunity" for nutrition to be a significant part of the current lobster recruitment research program.
Effects of Environmental Forcing on Age-Structured Populations: Northern California Dungeness Crab (Cancer magister) as an Example
Authors: Botsford Louis W.
Published: February 2009

Evaluation of potential environmental effects on recruitment requires knowing how environmental forcing can affect recruitment and subsequent catch, and how these effects depend on life history. General relationships between a time series of an environmental forcing variable, the resulting time series of recruitment, and the subsequent time series of catch or abundance are described here for a fishery in which environmental forcing affects density-dependent recruitment and the population is fished at a constant rate. For a stable population with overcompensatory, density-dependent recruitment, the recruitment time series will resemble the environmental time series except that frequencies near 1/(2 × mean age in the population) will be emphasized. The amount of selective emphasis will depend on the degree of overcompensation, harvest rate, and width of the cohort size distribution (in a size-selective fishery). For a population harvested at constant rate, the catch time series will resemble the recruitment time series except that lower frequencies will be emphasized. The degree of selective emphasis will depend on harvest rate and width of the cohort size distribution. Application of these results to Dungeness crab (Cancer magister) research has allowed analysis of combined effects of density dependence and environmental forcing. They show (1) that criteria formerly used to evaluate density-dependent recruitment mechanisms were too strict, (2) that female harvest could reduce harvest variability due to environmental forcing, and (3) how a nonlinear influence of spring wind stress in combination with density-dependent recruitment could cause the observed catch record. Implications for other crustacean populations are discussed.
Effect of Assumptions about the Stock–Recruitment Relationship on a Lobster (Homarus gammarus) Stock Assessment
Authors: Bannister R. C. A. , Addison J. T.
Published: February 2009

Stock assessment of the European lobster (Homarus gammarus) has involved yield per recruit analysis based on the established length cohort methodology of Jones (1974. ICES C.M. 1974/F:33; 1981. FAO Fish. Circ. 734) which assumes that recruitment to the fishery is independent of spawning stock. The Shepherd (1982. J. Cons. Int. Explor. Mer 40: 67–75) model has been used to simulate a range of assumed stock–recruitment relationships, and the resulting sensitivity analysis describes how these affect the relation between yield or biomass and four management variables, namely fishing mortality, minimum carapace length, maximum carapace length, and the capture or noncapture of egg-bearing females. Yield curves show a clear maximum with a marked tendency to stock collapse when fishing effort is high. For the range of simulations considered, the probability of an early recruit failure is greatest for asymptotic stock–recruitment curves, which generate yield curves with maxima at an effort substantially lower than the present level. Only with a highly overcompensatory stock–recruitment curve is there a case for increasing effort to maximise yield, but such a relationship tends to reduce the benefit of increasing minimum carapace length or of setting a maximum carapace length. The model predicts that the assumption made about the stock–recruitment relationship also has a marked effect on the results expected from a ban on the landing of egg-bearing females. Overall the results confirm the unsatisfactory prognosis of the yield per recruit model and emphasise the need to gain an understanding of the biological factors determining the shape of the lobster stock–recruitment curve.
Density-Dependent Mortality and the Relationship between Size Composition and Fishing Effort in Lobster Populations
Authors: Addison J. T.
Published: February 2009

Examination of time series data from lobster fisheries shows that although in some cases fishing mortality (estimated from size composition data) is directly related to fishing effort, that of many stocks remains relatively unchanged despite changes in the pattern of exploitation. This suggests that conventional stock assessment models used for finfish populations may not be adequate for lobster populations. A model is described which incorporates into a standard yield per recruit model density-dependent mortality in large lobsters due to limited availability of suitable holes in the substrate. The model predicts that size composition may change little with changes in fishing effort, and it is shown that current stock assessment methods may fail to detect those changes. The underlying assumptions of current methods are undermined further by the possible delay of moulting of lobsters that cannot find shelters.
Winter Distribution of Bearded Seals (Erignathus barbatus) in the Penny Strait Area, Northwest Territories, as Determined by Underwater Vocalizations
Authors: Cleator Holly J. , Stirling Ian
Published: February 2009

Vocalization surveys conducted in Penny Strait, Northwest Territories, indicated that before ice break-up, bearded seals (Erignathus barbatus) preferred regions of less stable ice where break-up occurred early and avoided stable, landfast ice or areas heavily used by walruses (Odobenus rosmarus). Water depth did not appear to influence distribution. Numbers of calls increased between mid-April and early June, probably because of an increase in rate of calling by individual seals. Vocalization surveys can be used to separate preferred habitats from unsuitable ones. Using a single hydrophone and our current understanding of bearded seal vocal behaviour, it is not possible to determine the absolute number of bearded seals at or near a site using vocalizations. However, it is possible to measure the relative abundance of seals for spatial and temporal comparisons.
Woody Debris, Channel Features, and Macroinvertebrates of Streams with Logged and Undisturbed Riparian Timber in Northeastern Oregon, U.S.A.
Authors: Carlson J. Y. , Andrus C. W. , Froehlich H. A.
Published: February 2009

Macroinvertebrate communities and several aspects of fish habitat were examined for 16 northeastern Oregon stream segments, 11 with undisturbed riparian forests and five where 26–54% of the riparian forest had been harvested 6 to 17 yr previously. Amounts of woody debris in streams and pools formed by the debris were similar between undisturbed and logged sites. Pool volume was inversely related to stream gradient and directly related to the amount of woody debris in the stream. Stream surface substrate composition was not significantly different between streams in logged and undisturbed areas. Macroinvertebrate density was 20 to 113 percent greater at the logged sites and diversity was similar at logged and undisturbed sites. Macroinvertebrates were most abundant at lower elevation streams and at streams that were shaded less by the surrounding vegetation. Timber harvesting activities do not appear to have damaged aquatic insect habitat and pool abundance was not altered, suggesting the habitat's carrying capacity for fish was not affected.
Effect of Copper on the interaction between the PredatorDidinium nasutumand its PreyParamecium caudatum
Authors: Doucet Christine M. , Maly Edward J.
Published: February 2009

Tests to determine acute copper toxicity levels demonstrated that the protozoan predator Didinium nasutum were more susceptible to copper stress than its prey Paramecium caudatum Thus we predicted that Paramecium and Didinium densities, at the equilibrium point of their interaction, would be higher at sublethal copper levels due to a decrease in the predator's efficiency. This situation is likely to produce a decrease in the stability of the system. However, isocline analysis did not support the predictions based on the acute lethality tests. Equilibrium densities of both predator and prey did not change at copper levels between 30 and 180 μg/L. The mathematical analysis suggested that the interaction became less stable with increasing copper concentrations. However, stability decreased due to hormesis in Didinium at sublethal copper levels and not due to a reduction in predator efficiency as expected. At 300 μg Cu/L, densities of both species at equilibrium were higher and the stability of the system decreased. This decrease in stability resulted from a reduction in predator efficiency, as 300 μg Cu/L is not sublethal for Didinium.
Effects of Chlorpyrifos on the Diet arid Growth of Larval Fathead Minnows, Pimephales promelas, in Littoral enclosures
Authors: Brazner John C. , Kline Edward R.
Published: February 2009

A series of 12 littoral enclosures constructed within a 2 ha, mesotrophic pond near Duluth, Minnesota were used to determine if sublethal concentrations of the insecticide chlorpyrifos [0,0,-diethyl 0-(3,5,6-trichloro-2-pyridyl) phosphorothioate] could lead to changes in the diet and growth of fathead minnow larvae. Chlorpyrifos was added to the enclosures at nominal concentrations of 0.0, 0.5, 5.0, and 20.0 μg/L in a single application on June 16, 1986. Growth rates of larvae were significantly reduced in the treated enclosures during the 32-d study period. The most dramatic differences in the mean size of larvae from the four treatment groups were observed 15 d posttreatment. These differences corresponded to the most significant reductions in cladoceran, copepod, rotifer, and chironomid populations in the treated enclosures. These results indicate that toxicity to chlorpyrifos-sensitive invertebrate forage species forced dietary changes that led to reduced growth of native fathead minnow larvae in the treated enclosures.
Effectiveness of Crab and Lobster Traps
Authors: Miller Robert J.
Published: February 2009

Traps are a versatile and powerful fishing gear. Desired species and sizes can be targeted through trap design and the choice of bait. Size of the catch is affected by trap size, bait quantity and quality, time between setting and hauling, and preventing escape through the entrance. But the largest potential for increasing trap catches is by increasing ease of entry and reducing the effect of gear saturation (animals inside traps preventing those outside from entering). Using catch per trap as an index of abundance is attractive for both fisheries management and ecological studies. However, correlations between catch and abundance have not been well established, probably because of the many factors affecting catchability (e.g. stage of the molt and reproductive cycles, sex, animal size, lunar and diurnal cycles, temperature, and water motion). Methods for conducting trapping surveys, measuring catchability, and comparing fishing strategies are critically reviewed.
Seasonal Variation in Spawning by Preovigerous American Lobster (Homarus americanus) in Response to Temperature and Photoperiod Manipulation
Authors: Waddy S. L. , Aiken D. E.
Published: February 2009

By manipulating temperature and photoperiod, we altered the incidence and timing of spawning in preovigerous American lobster (Homarus americanus), but the degree of alteration was affected by season. Females moved from natural conditions to unseasonably high temperatures (13–14 °C) and short daylengths (LD 8:16) beginning on 27 November did not spawn. Spawning rarely occurred (1%) when these conditions were started on 21 December (winter solstice), but after 8 January, there was a direct relationship between time spent at normal winter conditions and the incidence of spawning after environmental manipulation (8 January, 17%; 23 January, 45%; 8 February, 73%; 3 April, 82%; 12 May, 96%). Spawning occurred 26–42 d after photoperiod and temperature change, and the shortest times were associated with the longest periods of winter conditioning. Furthermore, a relatively brief exposure to normal winter environment enabled preovigerous lobster to disregard daylength and spawn in response to increasing spring temperature. This study indicates that spawning in response to environmental manipulation is altered by season, that duration of exposure to winter conditions influences the timing and incidence of spawning, and that different cues are utilized in different environmental regimes.
Institutional Learning and Spawning Channels for Sockeye Salmon (Oncorhynchus nerka)
Authors: Hilborn Ray
Published: February 2009

In the 1960s and 1970s, six artificial spawning channels for sockeye salmon (Oncorhynchus nerka) were constructed in British Columbia. I use the evaluation of these facilities and the response to the evaluation to test the hypothesis that fisheries management agencies can learn from experience. One of the facilities was almost immediately determined to be successful, but it took approximately 20 yr for the agency to evaluate the success of the other five. The evaluation was ambiguous for three of these. Only when facilities were overwhelmingly successful or total failures did clear answers emerge. The Canadian Department of Fisheries and Oceans (DFO) has experimented, evaluated, and learned about design, construction, and operation of spawning channels. DFO appears to be less successful at using the evaluation of adult production resulting from spawning channels. Learning appears to work best when goals are well defined, experiments can be conducted and evaluated rapidly, and there is a close organizational connection between decision makers, evaluators, and operators.
Assessment of Activity-Specific Metabolism of Aquatic Organisms: An Improved System
Authors: Davies Ronald W. , Wrona Frederick J. , Kalarani V.
Published: February 2009

An improved flow-through respirometer capable of assessing activity-specific metabolism of aquatic organisms is presented and assessed. The system is highly sensitive and versatile, since it continuously monitors and records activity-specific oxygen consumption readings for periods up to 72 h and is capable of detecting differences in metabolism of individual specimens of similar weight. Using this system, we demonstrated individual variation and intraspecific differences in metabolism between two size classes of the freshwater leech Nephelopsis obscura and interspecific differences between N. obscura and another freshwater leech, Erpobdella montezuma, and compared these findings with the metabolism of the amphipod Hyalella montezuma.
Osmoregulatory Failure and Death of First-Year Largemouth Bass (Micropterus salmoides) Exposed to Low pH and Elevated Aluminum, at Low Temperature in Soft Water
Authors: McCormick J. Howard , Jensen Kathleen M.
Published: February 2009

Young-of-the-year largemouth bass (Micropterus salmoides) were exposed to pH levels from 8.0 to 4.5 in two water types, 1.5 and 13.4 mgCa/L. Exposures were conducted at 3.8 °C for 113 d, followed by 14 d of increasing temperature to 18 °C. Two treatments in the softer water, one each at pH 5.0 and 4.5, had Al added to attain 30 μg Al/L; all other treatments were at approximately 5 μg Al/L. The condition factor of fish in all treatment groups declined with exposure time at 3.8 °C. Fish in the 13.4 mg Ca/L water maintained osmotic homeostasis through pH 5.0. In the 1.5 mg Ca/L water, osmotic homeostasis was lost at pH 4.5 and at pH 5.0 when Al was added. Mortalities were most prevalent when exposed in the 1.5 mg Ca/L water with added Al. The probability of survival was directly correlated with blood osmolality; no correlation was found between survival probability and condition factor. A rise in blood osmolality occurred among fish from most exposure groups when the temperature was increased to 18 °C. When fish from these chronic treatments were challenged at pH 3.8, they had shorter survival times in the softer water and after longer preexposures.
Effects of Nutrient Enrichment and Flood Frequency on Periphyton Biomass in Northern Ozark Streams
Authors: Lohman Kirk , Jones John R. , Perkins Bruce D.
Published: February 2009

Ambient nutrient concentrations (TN and TP) and periphyton biomass (Chl a) were measured every 2 wk during March–November in 1985 and 1986 at 22 sites on 12 streams in the northern Ozarks, Missouri. Benthic Chl a was positively correlated in both years with log TN (R2 = 0.58, 0.60) and with log TP (R2 = 0.47, 0.60). When sites were grouped by the degree of enrichment and plotted over time, benthic Chl a decreased at all sites after flood events, but rebounded more rapidly at highly enriched sites. Differences in recovery following flooding were most obvious in fall 1986, when both high and moderately enriched sites exhibited similar biomass accrual patterns, reaching mean benthic Chl a of 397.4 and 321.1 mg∙m−2, respectively, within 42 d after a catastrophic flood. In contrast, average benthic Chl a at nutrient-poor sites reached a maximum level of 76.8 mg∙m−2 within 28 d after flooding, suggesting that maximum standing crops are influenced by both nutrient supply and the length of the flood-free period.
Phosphate and Iron Limitation of Phytoplankton Biomass in Lake Tahoe
Authors: Chang Cecily C. Y. , Kuwabara James S. , Pasilis Sofie P.
Published: February 2009

Field measurements and bioassay experiments were coupled to investigate the interdependent processes affecting phytoplankton biomass at Lake Tahoe using a trace metal protocol. Water samples were analyzed for suspended particulate matter, dissolved organic carbon, major ions and macronutrients, adenosine triphosphate, and phytoplankton abundance. Concentrations of total Cd [Formula: see text], Cu (2.25–8.85 nM), and Fe (22–49 nM) were similar to or lower than those reported for other oligotrophic lakes. Bioassays were carried out to assess the response of inoculated, single-species diatom populations (Cyclotella meneghiniana and Aulocosiera italica) to additions of synthetic chelators (EDTA, EDDHA) and phosphate. A chemical speciation model along with the field data was also used to predict how trace metal speciation, and hence bioavailability, was affected by the chelator additions. Results suggest that phosphate was limiting to phytoplankton biomass. Other solutes, Fe in particular, may also exert controls on biomass. Nitrate limitation seems less likely, although Fe-limiting conditions, as suggested by the bioassays, may have led to an effective N limitation because algae require Fe to carry out nitrate reduction. Small perturbations in water chemistry may have pronounced effects on phytoplankton biomass in oligotrophic systems where essential nutrients are at low concentrations.
A Comparison of von Bertalanffy and Polynomial Functions in Modelling Fish Growth Data
Authors: Chen Y. , Jackson D. A. , Harvey H. H.
Published: February 2009

We compared the von Bertalanffy growth function (VBGF) and five polynomial functions (PF) in modelling fish growth for 16 populations comprising six species of freshwater fishes. Ranked results of the variance explained by each growth function indicated that VBGF described growth data better than three- and four-parameter polynomial functions. Log-transforming length and age greatly improved the goodness-of-fit of the three-parameter polynomial function. Statistical comparison of growth between populations or sexes was done using a general linear model for polynomial functions. An analysis of residual sum of squares was proposed to compare the resultant VBGFs because the nonlinear formulation of the VBGF prevented traditional analysis of covariance procedures. Fitting of different growth functions to the same growth data set yielded the same result in the intra-species growth comparisons for three species (eight populations) but different results for two species (seven populations). Where ages of the fish were less than the maximum age in the samples, dL/dt were similar for all growth functions except the parabola based on the log-transformation of length alone. The VBGF proved to be the best growth model for all 16 populations.
Optimal fineness ratio for minimum drag in large whales
Authors: Ahlborn Boye K. , Blake Robert W. , Chan Keith H.S.
Published: February 2009

The optimum fineness ratio (X = L/d, where L and d are body length and profile height, respectively) for minimum drag is about 4.5 and many fast swimming fish are characterized by values of this order. However, values for large whales that undergo extensive migrations (e.g., Balaenopteridae, Balaenidae, and Physeteridae) are as high as 8. A plot of fineness ratio versus mass (M) for different species of large whales shows that the optimal fineness ratio for minimum drag and therefore the minimum cost of transport increases slowly with increasing mass (X = 4M0.06). Optimal fineness ratio was determined from a simple hydromechanical model based on the sum of friction and pressure drag on an equivalent cylindrical body, which indicate a small positive dependence (0.11) of optimal fineness ratio for minimum drag with increasing body mass, suggesting an adaptation for reducing the energy cost of swimming.
Intrinsic and extrinsic sources of variation in the diets of harp and hooded seals revealed by fatty acid profiles
Authors: Tucker Strahan , Bowen W. Don , Iverson Sara J. , Stenson Garry B.
Published: February 2009

Individuals of different age, sex, and morphology are expected to exhibit differences in dietary niches largely owing to sexual dimorphism, ontogenetic niche shifts, and resource polymorphism. Harp ( Pagophilus groenlandicus (Erxleben, 1777)) and hooded ( Cystophora cristata (Erxleben, 1777)) seals are geographically overlapping and highly migratory predators in the North Atlantic Ocean. These species differ in their diving behaviour, with hooded seals diving deeper, longer, and more associated with the continental shelf edge and deep ocean than harp seals. We examined blubber fatty acid (FA) composition (N = 37; 93% of total FA by mass) of harp (adults N = 294; juveniles N = 232) and hooded (adults N = 118; juveniles N = 38) seals to test hypotheses about sources of intrinsic (age and sex) and extrinsic (geographic location, season, year) variations in diets. A significant difference in FA profiles suggested dietary segregation between species. We found significant effects of sex and age class on FA profiles, with these being more pronounced in the highly size-dimorphic hooded seals than in harp seals. FA profiles of both species also varied between inshore and offshore sampling locations and between prebreeding and postbreeding periods. Finally, FA profiles of harp seals differed among years, which was coincident with large changes in prey distribution and availability in the mid-1990s.
Influence of weather on two insectivorous bats in a temperate Pacific Northwest rainforest
Authors: Burles D. W. , Brigham R. M. , Ring R. A. , Reimchen T. E.
Published: February 2009

Adverse weather conditions frequently have a significant negative influence on survival and reproductive success of insectivorous bats. Low ambient temperatures increase the energetic costs of maintaining euthermia and reduces insect activity, while precipitation likely adds “clutter” making prey more difficult to detect using echolocation. We studied two species of insectivorous bats, Myotis lucifugus (LeConte, 1831) and Myotis keenii (Merriam, 1895), in the Pacific Northwest of Canada, a region that experiences frequent cool, wet weather during spring and summer. Our study took place during the El Niño – La Niña cycle of 1998–1999, which resulted in contrasting years. The summer of 1998 was unusually warm and dry, while the summer of 1999 was unusually cool and wet. We predicted that both species would be adversely affected by the cool, wet conditions of 1999, resulting in prolonged gestation, late fledging of young, and lower reproductive success. However, this was not the case. Myotis lucifugus did experience delays in reproductive timing and lower reproductive success in 1999, as predicted, whereas M. keenii experienced much shorter gestations, earlier fledgings, and no difference in reproductive success between years. We hypothesize that the ability of M. keenii to glean prey enables it to better cope with cool, wet conditions.
Population variation in hypoxic responses of the cichlid Pseudocrenilabrus multicolor victoriae
Authors: Martínez M. L. , Chapman L. J. , Rees B. B.
Published: February 2009

F1 offspring of the African cichlid Pseudocrenilabrus multicolor victoriae Seegers, 1990 from swamp (low oxygen) and lake (high oxygen) origin were raised under normoxia and submitted to hypoxia acclimation (0.8 ± 0.4 mg·L–1) and normoxia acclimation (7.4 ± 0.3 mg·L–1) for 4 weeks. Haematocrit and lactate dehydrogenase (LDH) specific activities in the liver, white skeletal muscle, heart, and brain were measured. For haematocrit and LDH activities of liver, muscle, and heart, the response to acclimation depended upon population of origin. In general, fish from the swamp population showed a more “typical” hypoxic response (increased haematocrit and LDH activities), whereas fish from the lake population either did not respond or showed the opposite response. The results suggest that populations of P. m. victoriae sampled from habitats with diverse oxygen regimes differ in their physiological and biochemical responses to hypoxia.
Selective feeding of pine voles on roots of tree seedlings
Authors: Schreiber L. A. , Swihart R. K.
Published: February 2009

Previous studies have implicated numerous physical and biotic factors as contributing to the failure of oak to regenerate successfully throughout substantial portions of eastern North America. Recent field evidence in southern Indiana implicated belowground herbivory by pine voles ( Microtus pinetorum (LeConte, 1830)) as a potentially important but overlooked mortality agent for oak seedlings. We used cafeteria-style feeding trials to determine whether selection of hardwood seedlings by captive pine voles differed according to species or age. White oak ( Quercus alba L.) was selected more frequently and experienced a greater proportion of root removal by pine voles than same-age seedlings of the other four species tested. Yellow poplar ( Liriodendron tulipifera L.) was never eaten. White oak seedlings 3 and 6 weeks of age suffered proportionately greater root removal than conspecific seedlings 12 and 15 weeks of age; pine voles removed roughly constant levels of root biomass irrespective of seedling age. Our results confirm that pine voles selectively feed on oak seedlings. In areas where pine voles are abundant, belowground herbivory could limit regeneration of oak by reducing seedling growth and survival. The importance of pine voles as factors influencing the success of oak regeneration warrants closer scrutiny in future field studies.