bluuebunny/crossref_metadata_2025 huggingface dataset:
Interrelations among rock lobsters, sea urchins, and juvenile abalone: implications for community management
Authors: Mayfield Stephen , Branch George M
Published: April 2011

Field and laboratory experiments demonstrate that juveniles of South African abalone (Haliotis midae) depend vitally on the protection from predation that they gain from living concealed beneath Cape urchins (Parechinus angulosus). Recent reports suggest that rock lobsters (Jasus lalandii) have increased substantially in the region where the commercial abalone fishery is centered. This increase has been blamed for a recorded collapse of urchin populations and dramatic reductions in the numbers of juvenile abalone. We verified the substantial increase in rock lobster abundance there. Surveys covering 200 km of coastline showed that densities of urchins were negatively correlated with those of large lobsters (>68 mm carapace length) and that densities of juvenile abalone were positively correlated with those of urchins. The indirect negative effects of rock lobsters on juvenile abalone clearly pose a major threat to the abalone industry, already under stress from poaching. Quantification of the relationship between juvenile abalone and urchins and between urchins and rock lobsters allows a forecast of the magnitude of lobster harvesting necessary to reduce them to a level at which urchins may recover and sustain juvenile abalone. The complex interactions involved emphasize the importance of an ecosystem approach for the management of these stocks.
An experimental test of metabolic and behavioural responses of benthic fish species to different types of substrate
Authors: Fischer Philipp
Published: April 2011

Behavioural and respiratory responses to different types of substrate were tested in burbot (Lota lota) and stone loach (Barbatula barbatula). Both species showed distinct diel cycles of activity and respiration rate, with highest values immediately after dusk and lowest during the day. In burbot, mean respiration rate over a 24-h cycle was 30% higher on pebble substrates compared with cobbles. During daytime, the difference increased to 86%, but no significant differences were found during the night. The results show that lack of adequate shelter may substantially affect metabolism and somatic growth rates in benthic fish. These effects occur even when no predator is actually present and shelter is not essential for survival. The results provide evidence that current theories on the effects of substrate and predation pressure should be applied to the benthic community with care. Because most of these theories are derived from epibenthic or pelagic model-species, where the actual presence of a threat is needed to modify behaviour and thus the specimens' metabolism, their validity for the benthic community seems to be limited. The availability of adequate shelter may be of more importance than other environmental resources for fish that have a high substrate affinity, even when no predator is actually present.
Colonization and development of stream communities across a 200-year gradient in Glacier Bay National Park, Alaska, U.S.A.
Authors: Milner Alexander M , Knudsen E Eric , Soiseth Chad , Robertson Anne L , Schell Don , Phillips Ian T , Magnusson Katrina
Published: April 2011

In May 1997, physical and biological variables were studied in 16 streams of different ages and contrasting stages of development following glacial recession in Glacier Bay National Park, southeast Alaska. The number of microcrustacean and macroinvertebrate taxa and juvenile fish abundance and diversity were significantly greater in older streams. Microcrustacean diversity was related to the amount of instream wood and percent pool habitat, while the number of macroinvertebrate taxa was related to bed stability, amount of instream wood, and percent pool habitat. The percent contribution of Ephemeroptera to stream benthic communities increased significantly with stream age and the amount of coarse benthic organic matter. Juvenile Dolly Varden (Salvelinus malma) were dominant in the younger streams, but juvenile coho salmon (Oncorhynchus kisutch) abundance was greater in older streams associated with increased pool habitat. Upstream lakes significantly influenced channel stability, percent Chironomidae, total macroinvertebrate and meiofaunal abundance, and percent fish cover. Stable isotope analyses indicated nitrogen enrichment from marine sources in macroinvertebrates and juvenile fish in older streams with established salmon runs. The findings are encapsulated in a conceptual summary of stream development that proposes stream assemblages to be determined by direct interactions with the terrestrial, marine, and lake ecosystems.
Drift pathways on the western Scotian Shelf and its environs
Authors: Shore Jennifer A , Hannah Charles G , Loder John W
Published: April 2011

Particle tracking and velocity streamlines in three-dimensional seasonal mean current and tidal-current fields are used to develop a Lagrangian view of circulation in the western Scotian Shelf region. The flow fields, taken from a finite element prognostic model, have pronounced spatial structure associated with topography and inflows, and this structure is explored with emphasis on implications for biological populations. The velocity streamlines show the seasonal variations in the locations of throughflows, closed (recirculation) areas, and associated saddle points. Particle tracking from the Browns Bank gadoid nursery provides a spring mean drift pattern and retention times similar to those observed. On-shelf drift pathways through Northeast Channel (with peak summer inflow) and the Scotian Gulf are identified and provide a mechanism for supplying slope water, nutrients, and organisms to shelf basins with significant vertical structure. The Nova Scotian Current provides a near-surface drift pathway from zooplankton overwintering sites in Emerald and Lahave basins to the Browns Bank region in spring and winter. A direct near-surface pathway from outer Browns Bank to outer Georges Bank across Northeast Channel provides the potential for farther downstream drift. Sensitivities to additional flow components are identified.
Allometry of natural mortality as a basis for assessing optimal release size in fish-stocking programmes
Authors: Lorenzen Kai
Published: April 2011

This study evaluates the use of general mortality-size relationships for the assessment of release size in stocked fisheries. Seven release experiments (53 stocking events) are analysed, using a survival model based on allometric mortality and linear-length growth, allowing variation between experiments in both the allometric exponent and the level of mortality at reference length or generalising in one or both of the parameters. Results support the existence of a consistent allometry that applies independently of the overall level of mortality. The best-performing model is one in which the length exponent of mortality is set to -1 a priori, while mortality at reference length is allowed to vary between experiments (ranging from 0.7 to 33 per year at 15 cm in the present study). Even though the allometry of mortality is constant, the relative survival advantage of stocking large fish increases with the level of mortality at reference length. Using the identified length exponent of mortality of -1, survival models are derived for the linear, exponential, and von Bertalanffy growth equations. The models can be used to assess alternative release sizes, given an estimate of mortality at reference length, to facilitate comparative studies and to aid in the design of release experiments.
Associations between flatfish abundance and surficial sediments in the eastern Bering Sea
Authors: McConnaughey Robert A , Smith Keith R
Published: April 2011

Spatially explicit relationships between pleuronectid flatfish abundance and surficial sediments in the eastern Bering Sea were investigated using published sediment descriptions and trawl survey data (1982-1994). Flatfish food habits were also examined because sediment properties are known to affect the distribution and abundance of benthic prey. For six species, we compared sediment textures in areas of highest and lowest abundance (kilograms per hectare). Sand predominated in areas of high yellowfin sole (Pleuronectes asper) (YFS) (p << 0.001) and rock sole (Lepidopsetta spp.) (RS) (p << 0.001) abundance, while mixed sand and mud was most common in areas of lowest abundance. In contrast, mixed sand and mud predominated in areas preferred by flathead sole (Hippoglossoides elassodon) (FHS) (p << 0.001), Alaska plaice (Pleuronectes quadrituberculatus) (AP) (p = 0.002), and arrowtooth flounder (Atheresthes stomias) (ATF) (p = 0.004), with more diverse substrates in low-density areas. Areas of high and low Greenland turbot (Reinhardtius hippoglossoides) (GT) (p = 0.845) abundance had similar sediment textures (primarily mixed sand and mud). Species with highly restricted diets (AP) or piscivores with weak sediment associations (GT, ATF) had relatively inflexible food habits, whereas YFS, RS, and FHS food habits varied considerably with sediment type. Our findings suggest that benthic-feeding pleuronectids prefer certain sediment textures because of adaptive differences in prey availability.
The influence of stock structure and environmental conditions on the recruitment process of Baltic cod estimated using a generalized additive model
Authors: Cardinale M , Arrhenius F
Published: April 2011

The recruitment process and its underlying mechanisms are among the most studied phenomena in fisheries ecology. Traditional models estimate fish recruitment assuming a direct relationship with spawning stock size. However, highly variable environmental conditions, feeding conditions, and other factors can influence and complicate the results of a simple linear regression analysis between stock and recruitment. We used generalized additive models (GAMs) to investigate the influence of environmental conditions and stock structure on the recruitment processes of Baltic cod. The interaction between abiotic factors and old spawners (>5+ years) and eggs produced by old spawners were the most significant explanatory variables. Eggs produced by young spawners have a positive impact on cod recruitment only at high levels of reproductive volume, while old spawners' eggs have the highest positive effect at low levels of reproductive volume. Here we show: (i) that the number of Baltic cod recruits is strictly dependent on the age structure of the population; (ii) that interactions between biotic and abiotic factors are crucial in explaining recruitment variability; and (iii) that GAMs are a powerful technique for defining and quantifying the intricate multidimensional relationship between biotic and abiotic variables involved in recruitment processes.
Reconstructing the stock-recruit relationship for Northeast Arctic cod using a bioenergetic index of reproductive potential
Authors: Marshall C Tara , Yaragina Nathalia A , Ådlandsvik Bjørn , Dolgov Andrey V
Published: April 2011

Correlation and simulation analyses suggest that, for the Northeast Arctic (NA) cod stock, the total lipid energy (TLE (kJ)) contained in the livers of mature females is proportional to total egg production, making TLE a potential predictor of recruitment. Accordingly, the TLE of NA cod was estimated for a 51-year time period (1946-1996), using estimates of numbers at length derived from virtual population analysis, modelled values of proportion mature and weight at length, and observed values of the liver-condition index. A significant linear relationship between TLE and recruitment to age 3 was observed. The temporal trend in TLE suggests that the reproductive potential of the NA cod stock has been in decline since the mid-1970s. A multiple-regression model that included TLE, mean temperature, and mean alongshore wind stress as independent variables explained approximately 43% of the variation in recruitment. Reconstructing stock-recruit relationships using more sensitive measures of reproductive potential is the first step in resolving environmental effects on recruitment and in developing biological reference points that are more effective in stock conservation.
Application of fuzzy cluster analysis to Lake Simcoe crustacean zooplankton community structure
Authors: Nicholls Kenneth H , Tudorancea Claudiu
Published: April 2011

Fuzzy clustering generates cluster membership weights that indicate how tightly each object is linked to its cluster relative to other clusters of a dendrogram. In a fuzzy clustering of the crustacean-zooplankton taxa of Lake Simcoe, a large (720 km2) hardwater lake in Ontario, Canada, we show how the membership weights can be used to rank all taxa for their contribution to the sampling unit (SU) classification, where the total number of SUs was 84 (7 years × 12 sampling sites). The validity of the results was confirmed by comparison with other more traditional methods of identifying variables important for object classifications and by permutation tests of matrix correlation before and after removal of low-ranked and highly ranked species. Fuzzy clustering of Lake Simcoe SUs also revealed (i) the likelihood of trends in zooplankton community composition over the 7-year period and (ii) differences in composition possibly related to sampling-station depth. In particular, the shallowest sampling station in southern Cook's Bay had a zooplankton community structure that differed significantly from other stations during all years of the study. As a preliminary screening or data exploration tool, fuzzy clustering is particularly useful for analysis of ecological data.
The influence of smallmouth bass (Micropterus dolomieu) predation and habitat complexity on the structure of littoral zone fish assemblages
Authors: MacRae Pamela SD , Jackson Donald A
Published: April 2011

Fish assemblages in small lakes ([Formula: see text]50 ha) in central Ontario were characterized to determine the impact of smallmouth bass (Micropterus dolomieu) predation and habitat complexity on the structure of littoral zone fish assemblages. Data were collected employing minnow traps and visual assessment. Although species richness did not differ between lakes with and without smallmouth bass, species composition and relative abundance did differ. We identified two distinct fish assemblage types: one characterized by small-bodied species, mainly cyprinids, and a second by large-bodied centrarchid species, e.g., smallmouth bass. Smallmouth bass appear to reduce abundance, alter habitat use, and extirpate many small-bodied species such as brook stickleback (Culaea inconstans), fathead minnow (Pimephales promelas), pearl dace (Margariscus margarita), and Phoxinus spp.
Fish habitat modeling: from conceptual framework to functional tools
Authors: Boisclair Daniel
Published: April 2011

Natural and anthropogenic perturbations do not always equally affect all parts of an ecosystem, and all parts of an ecosystem do not equally contribute to maintain fish communities. The increasing pressure to use natural resources and to modify habitats led to the development of approaches to identify areas of key importance for fish communities. Following these approaches, aquatic systems could be perceived as puzzles, composed of a multitude of pieces with temporally flexible physical attributes and biological roles. Such a spatially explicit framework requires models that may allow one to predict fish distribution patterns and fish net energy gain once they have adopted a specific distribution pattern. Despite the conceptual appeal of spatially explicit approaches, functional tools may be obtained only after their assumptions have been tested and their models have been validated. Efforts must be deployed to identify temporal and spatial scales at which fish distribution and abundance should be estimated and modeled. Studies on fish behaviour and the energetic consequences of these behaviours must be conducted to insure that bioenergetic criteria used to define fish habitat quality do not depend on arbitrary assumptions about fish activity costs.
I: MARINE BIOLOGICAL STATION OF CANADA.: INTRODUCTORY NOTES ON ITS FOUNDATION, AIMS AND WORK
Authors: PRINCE E. E.
Published: April 2011

not available
Recent declines in benthic macroinvertebrate densities in Lake Ontario
Authors: Lozano Stephen J , Scharold Jill V , Nalepa Thomas F
Published: April 2011

Surveys of benthic macroinvertebrates conducted in Lake Ontario during 1994 and 1997 revealed recent declines in populations of three major taxonomic groups: Oligochaeta, Sphaeriidae, and Diporeia spp. (Amphipoda), with the most drastic reductions occurring in the latter. Results from sediment measurements were used to classify deepwater sediments into three habitat zones. Densities of all three taxa declined in the shallowest (1288 m) of the sediment zones between 1994 and 1997; the greatest changes in density were observed for Diporeia, which declined from 3011 to 145 individuals·m2, and for total benthic macroinvertebrates, which declined from 5831 to 1376 individuals· m2. Mean densities of Dreissena spp. in 1997 were highest in the shallowest zone, and the areas of greatest densities corresponded to areas of largest reductions in Diporeia populations. We believe that dreissenids are competing with Diporeia by intercepting the supply of fresh algae essential for Diporeia survival. A decline in macroinvertebrate densities, especially populations of an important food item such as Diporeia, in Lake Ontario sediments at depths of 1288 m may have a detrimental impact on the benthic food web.
Simulation of the planktonic ecosystem response to pre- and post-1976 forcing in an isopycnic model of the North Pacific
Authors: Haigh S P , Denman K L , Hsieh W W
Published: April 2011

To investigate the hypothesis that the 1976 "regime shift" in North Pacific fish populations resulted from climatic change propagating up the fisheries food web, we have embedded a four-component planktonic ecosystem model in an ocean general circulation model. The Miami isopycnic model (MICOM) has been implemented on a 2° grid over the domain from 18°S to 61°N, with a KrausTurner-type mixed layer model overlaying 10 isopycnal layers. An initial baseline run with forcing for the period 19521988 reasonably reproduces the spatial patterns and seasonal changes in SeaWiFS images. Estimates of annual net and export production compare well with contemporary observations of primary and export production at Ocean Station Papa in the subarctic North Pacific but are low by a factor of 810 at station ALOHA near Hawaii. Two subsequent runs with forcing for the periods 19521975 and 19771988 show the main gyres to strengthen after 1976 with large areas of increased mixed layer depth. In the light-limited subarctic, limited areas of shallower spring mixed layer produced increased phytoplankton biomass, whereas in the nutrient-limited subtropical gyre, increased nutrients (or migration of the subarctic front and the equatorial current system into the gyre) after 1976 correlated with increased plankton biomass.
Tidal currents and mixing in the Gulf of St. Lawrence: an application of the incremental approach to data assimilation
Authors: Lu Youyu , Thompson Keith R , Wright Daniel G
Published: April 2011

Tidal heights from 19 tide gauges around the Gulf of St. Lawrence are assimilated into a fully nonlinear, three-dimensional model using the incremental approach to data assimilation. The predicted sea level fields are realistic and agree with the assimilated tidal heights to within about 0.05 m at the M2 tidal frequency. The model also predicts tidal currents with useful skill. The prediction error at the M2 tidal frequency is typically less than 0.05 m·s1. The maps of predicted tidal currents are used to identify regions of mixed and stratified water in the Gulf of St. Lawrence using a version of the SimpsonHunter stability parameter, E. Overall, the map of E is in good agreement with a direct measure of water column stability based on observed density profiles.
The importance of influence diagnostics: examples from Snake River chinook salmon spawner-recruit models
Authors: Hinrichsen Richard A
Published: April 2011

The rapid decline of some salmonid populations in the Columbia River Basin led investigators to analyze spawner-recruit (SR) data in order to understand the potential gains of improving main-stem passage conditions and quantify the effectiveness of the juvenile transportation program. Direct measurements of passage survival and transportation were not always available, so instead, the researchers attempted to tease out the passage or transportation effects by using trends in production estimated from SR models. Small subsets of data, or even single observations, highly influenced the estimates of passage survival and transportation effectiveness derived from these models. For stream-type chinook salmon, deleting 1 of 13 stocks changed the estimate of main-stem passage survival from 11 to 34%. For ocean-type chinook salmon, the conclusion that transportation should be immediately halted hinged on a single observation. The Snake River salmon SR models starkly illustrate the importance of using influence diagnostics to temper inferences.
The influence of energetic requirements on the preferred temperature of overwintering juvenile Atlantic salmon (Salmo salar)
Authors: Morgan Ian J , Metcalfe Neil B
Published: April 2011

We used a horizontal temperature gradient to investigate the effect of alternate life history strategies and nutritional state on the preferred temperature of overwintering juvenile Atlantic salmon (Salmo salar L.). Contrary to our prediction, there was no significant difference in final preferred temperature between juvenile Atlantic salmon that will migrate to sea the following spring (early migrants) and those that show reduced growth and delay migration for at least another year (delayed migrants). Both migrant groups preferentially selected relatively low temperatures (<10°C), likely owing to their low appetite and growth rates. Food deprivation resulted in a significant increase, rather than our predicted decrease, in the final preferred temperature of the juvenile Atlantic salmon of approximately 2°C. We suggest that this is due to the need for an increased foraging effort to offset the projected energy deficit later in the winter. The final preferred temperature of delayed migrants increased from winter to spring, as predicted, coincident with increases in natural food availability and endogenous seasonal increases in appetite and growth rates. We conclude that the preferred temperature of overwintering juvenile Atlantic salmon may be influenced by future energetic requirements rather than the current level of energy reserves.
X: PRELIMINARY REPORT ON THE TREMATODES OF CANADIAN MARINE FISHES.
Authors: Stafford M.A., Ph. D. J.
Published: April 2011

not available
XIII: PROFESSOR MACALLUM ON THE CHEMISTRY OF MEDUSÆ. A CONDENSED RÉSUMÉ OF RESULTS
Authors: Prince Edward E.
Published: April 2011

not available
Accounting for responsive movement in line transect estimates of abundance
Authors: Palka D L , Hammond P S
Published: April 2011

A method is developed to account for effects of animal movement in response to sighting platforms in line transect density estimates using data on animal orientation. Models of expected distributions of animal orientation show that presence of responsive movement is determined by the ratio of animal sightings with angles of orientation in the third quadrant relative to the first quadrant. The distance at which response began is estimated using logistic generalized additive models of the relationship between radial distance and orientation. Density corrected for responsive movement is estimated by applying the Buckland and Turnock two-team analysis method to data poststratified into regions "close" to and "far" from (beyond the distance that responsive movement began) the observation platform instead of the original stratification by observation team. For data collected in the North Atlantic, white-sided dolphins, harbor porpoises, and minke whales responded by avoiding the survey ship, and white-beaked dolphins were attracted to the ship. For these populations, our method to correct for responsive movement gave significantly higher estimates, from 1.4 to 2.7 times the uncorrected estimates.
Assessing the production and the impact of cultivated oysters in the Thau lagoon (Mediterranee, France) with a population dynamics model
Authors: Gangnery A , Bacher C , Buestel D
Published: April 2011

The Thau lagoon (France) has been studied for many years because of its ecological interest related to economic activities: shellfish cultivation, tourism, and industry. The standing stock of cultivated filter feeders is around 20 000 t and consists of two main species, the Japanese oyster Crassostrea gigas and the Mediterranean mussel Mytilus galloprovincialis. To predict changes in the standing stock and the annual production, a mathematical model of the population dynamics was defined. It was based on the continuous equation of the density as a function of the mortality rate, the individual growth rate, and the interindividual variability. The daily growth rate was derived from field surveys and depended on the phytoplankton concentration and individual weight. The model also took into account the rearing strategy of the producers defined by the timetable of seeding and harvesting, obtained by an inquiry among the producers and used to simulate real cases of standing stock changes. The model was also used to assess the potential impact on the environment through the computation of the food consumption, which was compared with the residence time and the primary production.
A general framework for integrating the standardization of catch per unit of effort into stock assessment models
Authors: Maunder Mark N
Published: April 2011

A general framework is presented for integrating the standardization of catch per unit of effort (CPUE) into stock assessment models. Catchability is modeled using both continuous and categorical explanatory variables. The likelihood for the CPUE data is combined with the other likelihoods from the stock assessment model; the parameters used to model catchability are estimated simultaneously with the other parameters of the stock assessment model. The method is applied to a New Zealand rock lobster (Jasus edwardsii) stock, and the results are compared with those obtained using a generalized linear model. The point estimates are similar for both methods, but the confidence intervals from the integrated framework are much narrower. Simulation analysis supports the findings that the integrated approach gives narrower confidence intervals that more accurately represent the uncertainty in the parameter estimates, provided the model is correct.
Decadal changes in phytoplankton color index and selected calanoid copepods in continuous plankton recorder data from the Scotian Shelf
Authors: Sameoto D
Published: April 2011

Continuous plankton recorder data for phytoplankton color index, total diatoms, Calanus finmarchicus stages 14 and 56, C. glacialis, C. hyperboreus, and ParacalanusPseudocalanus spp. collected between the years 1961 and 1998 in the Canadian Atlantic region were analyzed for geographic and temporal changes. Significant differences in both geographic and temporal scales were detected. Changes were observed in all taxa during 19911998 with the phytoplankton color index increasing significantly (P = 0.05). A shift in the climatology occurred after 1991 as concentrations of C. finmarchicus and ParacalanusPseudocalanus became significantly higher (P = 0.05) in the first 3 months of the year compared with the years 19611974. Multiple linear regressions calculated between various biological taxa and the storm, temperature, and stratification indices showed that these physical indices explained between 21 and 51% of the multiple regression variance.
Recovery of ovary size, follicle cell apoptosis, and HSP70 expression in fish exposed to bleached pulp mill effluent
Authors: Janz David M , McMaster Mark E , Weber Lynn P , Munkittrick Kelly R , Kraak Glen Van Der
Published: April 2011

We hypothesized that impaired ovarian function (e.g., reduced ovary size) in wild fish chronically exposed to bleached pulp mill effluents is related to an increased rate of apoptosis in ovarian follicle (granulosa and (or) theca) cells. In 1996, vitellogenic white sucker (Catostomus commersoni) collected downstream of a bleached kraft pulp mill had reduced ovary size associated with increases in ovarian cell apoptosis and stress protein (HSP70) expression when compared with fish collected from an upstream reference site. Fish sampling was repeated in 1998 following mill maintenance changes aimed at minimizing the discharge of process chemicals. In 1998, there were no differences in ovary size, ovarian cell apoptosis, or ovarian HSP70 levels between fish collected upstream and downstream of the mill. Based on the results of this and our previous work, we conclude that chronic stimulation of ovarian cell apoptosis by certain components of mill effluents may represent an important cellular mechanism responsible for reductions in ovary size, and potentially other integrated reproductive responses, in female fish exposed to pulp mill effluents.
Estimating predation mortality in the Georges Bank fish community
Authors: Tsou Tien-Shui , Collie Jeremy S
Published: April 2011

Multispecies virtual population analysis (MSVPA) is one of the most successful methods of including predation in fishery models. By applying MSVPA to nine important fish species on Georges Bank, we estimated predation mortality of prey species, fishing mortality, and population abundance from 1978 to 1992. One of the inputs to the MSVPA, relative stomach content, was estimated by fitting gamma distributions to the logarithmic predator-to-prey size ratios. Chi-square tests indicated that the gamma distributions fit the observed ratios well. Predation mortality was highest at ages 0 and 1. Total biomass of all species remained relatively constant with decreasing predator biomass and increasing prey biomass. MSVPA requires extensive input data, and the uncertainty in the inputs will propagate into the model output. The sensitivity of MSVPA to perturbations in the inputs was assessed with a two-level fractional factorial design. Results of the sensitivity test indicated that MSVPA outputs were most sensitive to predator consumption rates and terminal fishing mortalities. With ±25% perturbations to the input parameters, MSVPA outputs varied within ±10% of the levels from the base run. Therefore, MSVPA appears to be relatively robust to uncertainty in the input data.
Identifying cause in sediment assessments: bioavailability and the Sediment Quality Triad
Authors: Borgmann U , Norwood W P , Reynoldson T B , Rosa F
Published: April 2011

Application of the Sediment Quality Triad approach to non-pH-stressed Sudbury area lakes clearly demonstrated increased metal (Cd, Co, Cu, and Ni) contamination, decreased abundances of some benthic invertebrates (amphipods, pisidiid clams, and tanytarsiid midges), and severe sediment toxicity to amphipods and mayflies. However, the bioavailability of metals and the cause of biological effects cannot be identified from these data. Bioaccumulation measurements, however, clearly demonstrated increased Cd, Co, and Ni bioavailability to Hyalella. Copper concentrations in Hyalella were not elevated, in spite of much higher sediment Cu concentrations. Nickel was the only metal accumulated in sufficient amounts to cause toxicity. Toxicity in Hyalella caged above the sediments was equivalent to that of animals exposed directly in sediment, demonstrating that effects were due to dissolved metal and not metals in the solid phase. Copper concentrations in overlying water were much lower than Ni concentrations and insufficient to account for toxicity. Including bioaccumulation data with traditional measurements of sediment chemistry, benthic community composition, and sediment toxicity allows quantification of metal bioavailability and identification of the cause of toxicity. This approach results in a much more complete assessment of the biological impacts of metals in sediments.
Resolving allegations of oil damage to incubating pink salmon eggs in Prince William Sound
Authors: Brannon Ernest L , Collins Keya CM , Moulton Lawrence L , Parker Keith R
Published: April 2011

The Exxon Valdez Oil Spill Trustee Council concluded that oil caused mortality of pink salmon (Oncorhynchus gorbuscha) eggs in Prince William Sound streams. Their conclusion was based primarily on Alaska Department of Fish and Game (ADF&G) studies which reported that mean mortality of embryos in eggs was higher in oiled than non-oiled streams when sampled shortly after spawning completion. However, developing embryos are vulnerable to shock mortality for a period of 20 days after fertilization, and the embryos in eggs from the latest spawners were still in the sensitive period at the time sampling took place. We argue that the original ADF&G analysis should have included sample timing in statistical comparisons of mortality between streams. Analysis of a subset of the ADF&G data showed that sampling shock was a major source of embryo mortality in these samples, and that source of mortality in the original survey would likely have been mistakenly interpreted as an oiling effect. Compensating for sample timing removed all statistical evidence for an oiling effect in the data subset. We conclude that the ADF&G study design confounded the ability to assess for the effect of oil exposure on pink salmon eggs.
Rapid communication / Communication rapide Invasion of transgenes from salmon or other genetically modified organisms into natural populations
Authors: Hedrick Philip W
Published: April 2011

In recent years, there has been widespread concern about the ecological and genetic effects of genetically modified organisms. In salmon and other fishes, transgenic growth hormone genes have been shown to have large effects on size and various traits related to fitness. In this paper, I have shown by using a deterministic model that if such a transgene has a male-mating advantage and a general viability disadvantage, then the conditions for its invasion in a natural population are very broad. More specifically, for 66.7% of the possible combinations of the possible mating and viability parameters, the transgene increases in frequency, and for 50% of the combinations, it goes to fixation. In addition, by this increase in the frequency of the transgene, the viability of the natural population is reduced, increasing the probability of extinction of the natural population. These findings provide independent confirmation of previous concerns about the inherent risks of transgenic organisms, especially for native salmon populations potentially affected by commercial salmon production using transgenic stocks.
Stable isotope composition of walleye: 15N accumulation with age and area-specific differences in δ13C
Authors: Overman Nathanael C , Parrish Donna L
Published: April 2011

Stable nitrogen and carbon isotope ratios were measured for walleye (Stizostedion vitreum) collected across Lake Champlain, Vermont, to determine relationships between isotopic composition and diet, location of capture, length, weight, and age. Variation in δ13C values reflected area-specific differences in isotopic composition of organisms collected across the lake. A critical assumption in the application of isotope techniques is that a predictable relationship exists between the diet and isotopic composition of an organism. Our results indicate that isotopic fractionation factors may not be independent of age as has largely been assumed. By combining stable nitrogen and carbon isotope analysis with conventional stomach content analysis, we documented significant age effects in the δ15N composition of adult walleye that were not attributable to observed changes in diet. Age accounted for 81% of the variation in δ15N values of walleye (ages 227, N = 65, δ15N range = 15.319.2), providing evidence supporting 15N accumulation over the life span of walleye. Therefore, the risk of making faulty inferences of trophic position and food web interactions based on δ15N values may be increased when age is unknown. Our results indicate that metabolic effects associated with age require greater consideration in applications of stable isotope analysis.
Prey capture ability of mummichogs (Fundulus heteroclitus) as a behavioral biomarker for contaminants in estuarine systems
Authors: Weis Judith S , Samson Jennifer , Zhou Tong , Skurnick Joan , Weis Peddrick
Published: April 2011

Prey capture was evaluated as a behavioral biomarker of contamination by examining feeding behavior of adult mummichogs (Fundulus heteroclitus) from 13 sites. Prey capture ability was related to sediment and tissue contaminant levels and with previous genetic analyses. The levels of contaminants at a site were highly correlated with each other, confounding the impacts of individual contaminants. The number of prey (grass shrimp) captured was highest in three of the cleanest sites. Sites with the lowest capture rates were generally more contaminated. The number of captures at all sites was highly variable, with both high and low efficiencies in highly contaminated populations. A significant relationship exists between the Mdh-A(a) allele and captures, with higher captures in the southern populations. Gut content analysis of field-collected fish had grass shrimp as the largest proportion of the diet at sites whose fish had the highest laboratory capture rates. Thus, prey capture as a behavioral biomarker is ecologically relevant and corresponds to diet in the field. However, it is not especially sensitive due to great variability at each site. Behavioral differences related to overall contaminant levels rather than to specific toxicants.
Predicting mercury levels in yellow perch: use of water chemistry, trophic ecology, and spatial traits
Authors: Greenfield Ben K , Hrabik Thomas R , Harvey Chris J , Carpenter Stephen R
Published: April 2011

Recent research suggests that wetland abundance surrounding lakes, fish trophic position, and fish community composition may influence the bioavailability of mercury (Hg) to fish. To compare the importance of these spatial and biological factors to chemical factors known to influence bioavailability, we determined the relationship between 24 lake traits and Hg concentrations in yellow perch (Perca flavescens; whole fish samples) for 43 northern Wisconsin lakes. Independent variables included biological traits such as fish trophic position and body condition, spatial traits such as lake hydrologic position and surrounding wetland abundance, and chemical traits such as pH and water color. The strongest predictor of fish Hg levels was pH (R2 = 0.42; p < 0.002). Of the biological traits measured, yellow perch body condition explained significant additional variation (final R2 = 0.54; p = 0.024). Trophic position explained limited variability and population abundance of planktivores and piscivores were not correlated to perch Hg levels. Regression tree models indicated that small lakes with greater than 6% wetland in their watershed have moderately elevated fish Hg levels. Our results indicate that within-lake chemistry and fish growth patterns are stronger correlates of Hg levels in yellow perch than spatial traits, trophic position, or fish community attributes.
Recovery of zooplankton assemblages in mountain lakes from the effects of introduced sport fish
Authors: Donald David B , Vinebrooke Rolf D , Anderson R Stewart , Syrgiannis Jim , Graham Mark D
Published: April 2011

Impacts of introduced fish on zooplankton assemblages of lakes may persist for decades following fish removal. We tested this hypothesis by comparing zooplankton assemblages from four categories of lakes located in western Canadian mountain parks including lakes without and with fish that differed in their fish community complexity and fish-stocking history. Zooplankton species richness was greatest in lakes with a complex community of fish and least in pristine fishless lakes. Canonical correspondence analysis showed that taxonomic shifts in zooplankton assemblages could be attributed to differences in fish-stocking history between the study lakes. In fishless lakes, larger copepods (Eucyclops agilis, Diaptomus leptopus), cladocerans (Diaphanosoma, large Daphnia), and chaoborids were abundant, whereas in the presence of fish, small crustaceans were more common and chaoborids were relatively rare. Once introduced trout were absent from lakes, recovery trajectories for zooplankton showed a general taxonomic shift towards assemblages characteristic of fishless lakes that had never been fish stocked. Based on separation between previously stocked fishless lakes and naturally fishless mountain lakes in ordination space (chi-squared distance), taxonomic recovery by zooplankton assemblages from the influence of introduced salmonids may require an average of 19 years.
A new model of growth back-calculation incorporating age effect based on otoliths
Authors: Morita Kentaro , Matsuishi Takashi
Published: April 2011

We developed a simple back-calculation model that includes the age effect in which otolith size increases continuously during no-growth periods. To evaluate the validity of our proposed model, we back-calculated the past fish lengths and growth rates using the new model and seven traditional back-calculation models (scale-proportional hypothesis (SPH), body-proportional hypothesis (BPH), FraserLee, biological intercept, nonlinear SPH, nonlinear BPH, and modified Fry) using the otoliths of individually tag-recaptured white-spotted char (Salvelinus leucomaenis). The estimated fish lengths corresponded well to observed fish lengths for simple traditional (SPH, BPH, and FraserLee) and the new models. However, the back-calculated growth rates did not correspond to observed growth rates except for the new model. All previous models had considerable bias; growth rates of slow-growing fish were overestimated. As our model incorporating the age effect did not show such bias, this bias would be attributed to the age effect. Our proposed back-calculation model incorporating the age effect should be useful to estimate past growth rates at the individual level.
Sensitivity of zooplankton for regional lake monitoring
Authors: Stemberger Richard S , Larsen David P , Kincaid Thomas M
Published: April 2011

We present a general method for evaluating and selecting indicators for regional monitoring based on an analysis of the relative magnitude of spatial and temporal components of variation. As part of a pilot survey of 355 lakes in the northeastern U.S.A., we sampled zooplankton assemblages and evaluated candidate indicators for their components of variance. Indicators with high sensitivity for status estimation show strong lake-to-lake differences as defined by the ratio of the spatial component of variance divided by the remaining components. Sensitivity generally increased within spatial partitions of the larger Northeast region. Calanoid abundance indicators showed the highest sensitivity but only within the Adirondack Mountains and coastal/urban zone and had low sensitivity in region-wide estimates. Rotifer, cyclopoid copepod, and cladoceran abundances showed low sensitivity irrespective of subregions. Richness indicators also showed low sensitivity across subregions. We conclude that sensitivity can be increased for many zooplankton indicators with increased revisit sampling and with refinement of spatial boundaries. Our results also show a good correspondence within abundance indicators between first and second visits within a year. Hence, the single visit protocol of the sampling design provides a reasonable snapshot of the general structure of a lake's zooplankton assemblage.
Environmental and biological factors associated with the stage-specific abundance of brown shrimp (Penaeus aztecus) in Louisiana: applying a new combination of statistical techniques to long-term monitoring data
Authors: Haas Heather L , Lamon III E Conrad , Rose Kenneth A , Shaw Richard F
Published: April 2011

Several short-term and small-scale correlative studies have associated brown shrimp (Penaeus aztecus) recruitment with high densities of sub-adults, high salinity, warm temperature, low river flow, and low precipitation. In this paper, we address criticisms of traditional correlative studies by using a spatially and temporally extensive dataset, by comparing stepwise multiple regression (SMR) to Bayesian model averaging (BMA), and by investigating nonlinear relationships with generalized additive models (GAMs). We use this combination of statistical methods to examine relationships between annual, stage-specific abundance estimates and environmental factors. BMA and SMR resulted in models with similar explanatory power, but BMA suggested fewer linear predictors. GAMs did not suggest nonlinear relationships among stage-specific abundance estimates. Postlarval abundance was not well described by any model. Juvenile abundance was partially described by environmental variables such as temperature, water clarity, and water level. Adult abundance was well described by early-juvenile abundance, salinity, and temperature. These results suggest that juvenile abundance may be the critical component in determining year-class strength of brown shrimp. Identifying mechanisms that regulate juvenile production within the estuary will be a critical step in effectively managing Louisiana's brown shrimp resource.
III.: NOTES ON THE ACTINIÆ OCCURRING IN THE NEIGHBOURHOOD OF THE BIOLOGICAL STATION, ST. ANDREWS, N.B.
Authors: McMurrich M.A., Ph. D. J. Playfair
Published: April 2011

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XVIII. THE TEMPERATURES AND DENSITIES AND ALLIED SUBJECTS OF PASSAMAQUODDY BAT AND ITS ENVIRONS. THEIR BEARING ON THE OYSTER INDUSTRY.
Authors: Copeland B. A. G. G.
Published: April 2011

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VI.: THE FRESH-WATER MALACOSTRACA OF ONTARIO.
Authors: Huntsman B. A., M. B. A. G.
Published: April 2011

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X.: PRELIMINARY REPORT ON THE PLANTS OF GEORGIAN BAY.: A Contribution to the Biology of the Georgian Bay Waters.
Authors: MacClement M.A., D.Sc. W. T.
Published: April 2011

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XIII.: ENTOMOSTRACA OF GEORGIAN BAY.
Authors: Sars G. O.
Published: April 2011

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XIII.: VARIATIONS IN DENSITY AND TEMPERATURE IN THE COASTAL WATERS OF BRITISH COLUMBIA—PRELIMINARY NOTES.
Authors: Fraser M.A., Ph.D., C. McLean , Cameron M.A., B.Sc. A. T.
Published: April 2011

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XVII.: THE WATER AND IODINE CONTENTS OF SOME PACIFIC COAST KELPS.
Authors: Cameron M.A., B.Sc. A. T.
Published: April 2011

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ON THE LIFE-HISTORY OF THE COHO.
Authors: Fraser Ph.D. C. McLean
Published: April 2011

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AN INVESTIGATION OF OYSTER PROPAGATION IN RICHMOND BAY, P.E.I., DURING 1915.
Authors: NELSON PH.D. JULIUS
Published: April 2011

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NOTES ON THE PHYTO-PLANKTON OF THE BAY OF FUNDY AND PASSAMAQUODDY BAY.
Authors: Bailey M.A., Ph.D., LL.D., F.R. L. W.
Published: April 2011

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III: THE PEARLY FRESH-WATER MUSSELS OF ONTARIO.
Authors: Detweiler M.A. John D.
Published: April 2011

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VII: FURTHER HYDROGRAPHIC INVESTIGATIONS IN THE BAY OF FUNDY.
Authors: Craigie B.A. E. Horne , Chase B.A. W. H.
Published: April 2011

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VIII.: EXAMINATION OF AFFECTED SALMON, MIRAMICHI HATCHERY, NEW BRUNSWICK.
Authors: Harrison D.Sc., F.R. F. C.
Published: April 2011

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IX: REPORT ON AFFECTED SALMON IN THE MIRAMICHI RIVER, NEW BRUNSWICK.
Authors: Huntsman B.A., M.B., F.R. A. G.
Published: April 2011

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XV: HYDROGRAPHY IN PASSAMAQUODDY BAY AND VICINITY, NEW BRUNSWICK.
Authors: Vachon B.A., L.Ph. Alexander
Published: April 2011

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III.: Temperature and Specific Gravity Variations in the Surface Waters of Departure Bay, B.C.
Authors: Fraser C. McLean
Published: April 2011

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XII: The Diatoms of Canada.
Authors: Bailey LL.D., F.R.S.C. L. W. , Mackay LL.D., F.R.S.C. A. H.
Published: April 2011

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No. 2: A STUDY OF THE SEA MUSSEL (Mytilus edulis, Linn.)
Authors: MOSSOP M.A. BESSIE K. E.
Published: April 2011

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No. III: THE FISHES OF THE BAY OF FUNDY
Authors: HUNTSMAN A. G.
Published: April 2011

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