bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of experimental otter trawling on the macrofauna of a sandy bottom ecosystem on the Grand Banks of Newfoundland
Authors: Kenchington E LR , Prena J , Gilkinson K D , Gordon Jr. D C , MacIsaac K , Bourbonnais C , Schwinghamer P J , Rowell T W , McKeown D L , Vass W P
Published: April 2011

A 3-year otter trawling experiment was conducted on a deepwater (120146 m) sandy bottom ecosystem on the Grand Banks of Newfoundland that had not experienced trawling for at least 12 years. The benthic macrofauna were sampled before and after trawling and in reference areas. The 200 grab samples collected contained 246 taxa, primarily polychaetes, crustaceans, echinoderms, and molluscs. Biomass was dominated by propeller clams (Cyrtodaria siliqua) and sand dollars (Echinarachnius parma), while abundance was dominated by the polychaete Prionospio steenstrupi and the mollusc Macoma calcarea. The most prominent feature of the data was a natural decline in the total number of species, the total abundance, and the abundance and biomass of selected species between 1993 and 1995. The only immediate effect of trawling was seen in 1994 when the abundance of 13 species, the biomass of 11 species (mostly polychaetes), and the total abundance per grab were significantly lower. There was little evidence of long-term trawling effects. When trawling disturbance was indicated, it appeared to mimic natural disturbance, shifting the community in the same direction in multidimensional scaling ordination; no distinctive trawling signature was observed. However, the results of this experiment should not be uncritically extrapolated to the impacts of commercial trawling.
Production of stream habitat gradients by montane watersheds: hypothesis tests based on spatially explicit path analyses
Authors: Isaak Daniel J , Hubert Wayne A
Published: April 2011

We studied how the features of mountain watersheds interact to cause gradients in three stream attributes: baseflow stream widths, total alkalinity, and stream slope. A priori hypotheses were developed before being tested in a series of path analyses using data from 90 stream reaches on 24 second- to fourth-order streams across a fifth-order Rocky Mountain watershed. Because most of the conventional least squares regressions initially calculated for the path analyses had spatially correlated residuals (13 of 15 regressions), spatially explicit regressions were often used to derive more accurate parameter estimates and significance tests. Our final working hypotheses accounted for most of the variation in baseflow stream width (73%), total alkalinity (74%), and stream slope (78%) and provide systemic views of watershed function by depicting interactions that occur between geomorphology, land surface features, and stream attributes. Stream gradients originated mainly from the unidirectional changes in geomorphic features that occur over the lengths of streams. Land surface features were of secondary importance and, because they change less predictably relative to the stream, appear to modify the rate at which stream gradients change.
Effects of acclimation to brackish water on the growth, respiratory metabolism, and swimming performance of young-of-the-year Adriatic sturgeon (Acipenser naccarii)
Authors: McKenzie D J , Cataldi E , Romano P , Owen S F , Taylor E W , Bronzi P
Published: April 2011

Specific growth rates, exercise respirometry, and swimming performance were compared in young-of-the-year Adriatic sturgeon (Acipenser naccarii) maintained in freshwater (FW) or acclimated to brackish water (BW) that was slightly hypertonic to sturgeon plasma, at a salinity of 11 g·L1. Specific growth rate was significantly (17%) lower in BW than in FW. Sturgeon in BW also had a significantly (30%) higher standard metabolic rate than those in FW. In both groups, the relationship between swimming speed and oxygen uptake was described equally well by a linear or exponential equation, with a power relationship between swimming speed and net cost of locomotion and a linear relationship between tailbeat frequency and swimming speed. However, sturgeon in BW exhibited higher mean total oxygen uptake, net costs, and tailbeat frequencies than the FW group at any given swimming speed. There were, however, no differences in aerobic scope or maximum sustainable swimming speed between the FW and BW groups because the BW group exhibited a compensatory increase in active metabolic rate and maximum tailbeat frequency. The results indicate that FW is a more suitable environment than mildly hypertonic BW for young-of-the-year Adriatic sturgeon.
Spatial and temporal effects of interspecific competition between Atlantic salmon (Salmo salar) and brown trout (Salmo trutta) in winter
Authors: Harwood A J , Metcalfe N B , Armstrong J D , Griffiths S W
Published: April 2011

Previous work has shown that juvenile stream-dwelling salmonids become predominantly nocturnal during winter by emerging from daytime refuges to feed, with several species having been shown to prefer slow-flowing water while active at night. We used seminatural stream channels, landscaped to provide a choice of water depths, and hence velocities, to test whether Atlantic salmon, Salmo salar, and brown trout, Salmo trutta, show similar habitat preferences during winter. We also tested whether there was any spatial or temporal displacement of Atlantic salmon when in sympatry with brown trout. Nighttime observations revealed that Atlantic salmon did have a preference for slow-flowing water. However, when in direct competition with trout, salmon either remained predominantly nocturnal but occupied shallower water, or became significantly less nocturnal, spending more time active during the day than when in allopatry. These results, which were especially marked in relatively larger fish, indicate that competition between the two species for food and resources is not restricted to the summer months and may affect both the short- and long-term growth and survival of overwintering wild Atlantic salmon.
Fishing on ecosystems: the interplay of fishing and predation in NewfoundlandLabrador
Authors: Bundy Alida
Published: April 2011

In the early 1990s, Atlantic cod, a major component of the NewfoundlandLabrador ecosystem, suffered a stock collapse, and other groundfish stocks such as American plaice and yellowtail flounder seriously declined. This paper explores whether the relative effects of predation and fishing alone can account for these ecosystem changes. The NewfoundlandLabrador ecosystem was first modelled with a mass balance model for a time period in the mid-1980s when the groundfish biomass was relatively stable. This provided the starting point for simulations using a trophodynamic simulation model, Ecosim. A series of simulations were run, under different assumptions about energy control, to address the larger question "can the effects of fishing and predation account for the changes observed in the ecosystem?" The collapse and nonrecovery of cod was replicated, assuming top-down energy control. Other control assumptions were less successful. While groundfish stocks collapsed, seal populations and invertebrates such as shrimp and snow crab increased in abundance. The model predicted these increases, while a simulated increase in harp seals further repressed the recovery rate of cod. It was concluded that these results are consistent with the hypothesis that the collapse of cod was caused by excess fishing and that cod recovery is retarded by harp seals.
Testing assumptions of otolith radiometric aging with two long-lived fishes from the northern Gulf of Mexico
Authors: Baker, Jr. M Scott , Wilson Charles A , VanGent Daniel L
Published: April 2011

In this study, we evaluate the assumptions for estimating ages with radiometric and elemental analyses of otoliths of red snapper (Lutjanus campechanus) and red drum (Sciaenops ocellatus) from the northern Gulf of Mexico. In whole otoliths of both red snapper and red drum, 226Ra activity was inversely correlated with the otolith mass increase with age, validating the assumption that 226Ra accumulation in otoliths occurs at a rate proportional to that of Ca. 222Rn emanation from otoliths decreased as otolith mass increased. 222Rn loss occurred in all red snapper otolith samples ([Formula: see text]4.1%) and, to a lesser extent, in red drum otolith samples ([Formula: see text]0.6%) and decreased with increasing size (age) of the otolith. For red drum, the assumption that the initial activity ratio of 210Po to 226Ra in otoliths is essentially zero was indirectly validated with elemental analyses of Pb and Ba. Radiometric age estimation of shallow-water fishes from the northern Gulf of Mexico holds great promise, considering that 226Ra activities observed in this study are some of the highest recorded to date for species to which the 210Pb/226Ra dating technique has been applied.
Predictions of critical habitat for five whale species in the waters of coastal British Columbia
Authors: Gregr Edward J , Trites Andrew W
Published: April 2011

Whaling records from British Columbia coastal whaling stations reliably report the positions of 9592 whales killed between 1948 and 1967. We used this positional information and oceanographic data (bathymetry, temperature, and salinity) to predict critical habitat off the coast of British Columbia for sperm (Physeter macrocephalus), sei (Balaenoptera borealis), fin (Balaenoptera physalus), humpback (Megaptera novaeangliae), and blue (Balaenoptera musculus) whales. We used generalized linear models at annual and monthly time scales to relate whale occurrence to six predictor variables (month, depth, slope, depth class, and sea surface temperature and salinity). The models showed critical habitat for sei, fin, and male sperm whales along the continental slope and over a large area off the northwest coast of Vancouver Island. Habitat models for blue, humpback, and female sperm whales were relatively insensitive to the predictor variables, owing partially to the smaller sample sizes for these groups. The habitat predictions lend support to recent hypotheses about sperm whale breeding off British Columbia and identify humpback whale habitat in sheltered bays and straits throughout the coast. The habitat models also provide insights about the nature of the linkages between the environment and the distribution of whales in the North Pacific Ocean.
Herbivory in variable environments: an experimental test of the effects of vertical mixing and Daphnia on phytoplankton community structure
Authors: Beisner Beatrix E
Published: April 2011

Phytoplankton communities in lakes are exposed to different within-season frequencies of heterogeneity in resource supply because of wind-induced vertical mixing. Effects of such heterogeneity, in conjunction with herbivory, on phytoplankton community structure have rarely been simultaneously examined, despite the fact that each factor can have large effects on phytoplankton composition and diversity. This study uses replicated oligotrophic mesocosms to examine the effects of herbivory and different scales of temporal heterogeneity in deepwater mixing. The pattern of vertical mixing alone had minor effects on phytoplankton community diversity and composition. The herbivore Daphnia caused a shift in phytoplankton composition to less edible types, based mainly on morphological features (spiny shapes and trichomes on cell walls) rather than size structure alone. Phytoplankton richness depended jointly on mixing frequency and large Daphnia biomasses. When systems were well mixed, with high encounter rates between predator and prey populations, phytoplankton community richness was lowest. By contrast, the systems that were least often mixed had highest richness. These results are related to limited encounter rates with infrequent mixing and to the availability of refuges from predation. Responses to different scales of temporal heterogeneity in these oligotrophic phytoplankton communities depend more on Daphnia feeding than on resource pulsing.
Movement and harvesting mortality of American lobsters (Homarus americanus) tagged inside and outside no-take reserves in Bonavista Bay, Newfoundland
Authors: Rowe Sherrylynn
Published: April 2011

To determine the potential effectiveness of no-take reserves in sustaining fisheries for American lobster (Homarus americanus), lobster movement and survival were quantified both within and outside of two no-take reserves in Bonavista Bay, Newfoundland, during 19971999. Most (58.7%) tagged lobsters were recaptured in the immediate vicinity of their original capture location. Among lobsters that moved, 77.1% traveled less than 1000 m. Lobster movement resulted in some exchange between no-take reserves and nearby harvested areas (8.7% of lobsters recaptured were in an area different from their location of tagging). Overall, little evidence was found for a relationship between lobster movement and sex, size, or time at large. Annual harvesting mortality accounted for up to 71.9% for lobsters eligible for harvest. However, many more lobsters tagged outside of no-take reserves were harvested (11.571.9%) than those tagged in no-take reserves (0.018.5%), a result of low frequency of movement between these areas. No difference was found between female and male mortality as a result of the fishery. Because the frequency of lobster emigration from reserves was relatively low and harvesting pressure outside of reserves was intense, results suggest that no-take reserves can offer increased survival to lobsters and thereby may provide benefits to fisheries.
RAPID COMMUNICATION / COMMUNICATION RAPIDEEstablishment of two invasive crustaceans (Copepoda: Harpacticoida) in the nearshore sands of Lake Michigan
Authors: Horvath Thomas G , Whitman Richard L , Last Laurel L
Published: April 2011

Benthic copepods (Copepoda: Harpacticoida) in the nearshore sediments of southern Lake Michigan appear to be dominated by two new invasive species. We report the first occurrence in North America of Schizopera borutzkyi Montschenko, a native to the Danube River delta, and Heteropsyllus nr. nunni, likely a new species that is morphologically similar to the marine species Heteropsyllus nunni and represents the first occurrence of this genus in freshwater. Schizopera borutzkyi is a euryhaline species occurring in shallow sands in its native habitat and in deeper sands (615 m) in southern Lake Michigan. Based on the absence of these species from previous studies, we suggest that they are recent introductions. Heteropsyllus nr. nunni dominated (55100%) the harpacticoid abundance to depths of 9 m, but S. borutzkyi comprised 75% of the harpacticoid abundance at 15 m. Native harpacticoids were always greatly outnumbered by invasive harpacticoids in our samples, which suggests that the natives are being replaced rapidly or that the invasive species are finding unused resources. The ecological implications of these introductions are not known, but these invasions may represent continued "invasional meltdown" in Lake Michigan.
Maternal effects as a recruitment mechanism in Lake Michigan yellow perch (Perca flavescens)
Authors: Heyer Christopher J , Miller Thomas J , Binkowski Fred P , Caldarone Elaine M , Rice James A
Published: April 2011

Changes that occurred in the distribution of adult Lake Michigan yellow perch (Perca flavescens) phenotypic traits suggest that maternal effects on larval traits may be substantially influencing the recruitment of this heavily exploited species. We investigated maternal effects on yellow perch larvae at hatching in 10 maternal lines to test the null hypothesis of no effect of maternal phenotype on offspring phenotype and condition. Analyses lead to a rejection of the null hypothesis and indicated that the observed maternal effects likely resulted from differences among females in size, age, gonadosomatic index, and egg production. The observed maternal effects were expressed in the offspring by differences in larval total length, yolk volume, dry weight, and DNA quantity. Older, larger females were found to have high fecundity, yet low gonadosomatic index. Furthermore, older, larger females produced offspring that were, on average, short with large yolk sacs and high quantities of body reserves, as measured by dry weight and total DNA content. We conclude that the distribution of Lake Michigan yellow perch larval traits at hatching is linked to maternal influences and that this linkage may provide a mechanism through which managers can help rebuild the population.
Developing Baltic cod recruitment models. I. Resolving spatial and temporal dynamics of spawning stock and recruitment for cod, herring, and sprat
Authors: Köster Friedrich W , Möllmann Christian , Neuenfeldt Stefan , John Michael A St , Plikshs Maris , Voss Rüdiger
Published: April 2011

The Baltic Sea comprises a heterogeneous oceanographic environment influencing the spatial and temporal potential for reproductive success of cod (Gadus morhua) and sprat (Sprattus sprattus) in the different spawning basins. Hence, to quantify stock and recruitment dynamics, it is necessary to resolve species-specific regional reproductive success in relation to size, structure, and distribution of the spawning stock. Furthermore, as species and fisheries interactions vary between areas, it is necessary to include these interactions on an area-specific basis. Therefore, area-disaggregated multispecies virtual population analyses (MSVPA) were performed for interacting species cod, herring (Clupea harengus), and sprat in the different subdivisions of the Central Baltic. The MSVPA runs revealed distinct spatial trends in population abundance, spawning biomass, recruitment, and predation-induced mortality. Results, when evaluated with respect to trends in population sizes from research surveys, were similar for the cod and sprat stocks but different for herring. Horizontal distributions from MSVPA runs and research surveys indicate that cod and sprat undergo migrations between basins during different life stages. This is an observation potentially influencing estimates for the different stock components but not affecting the overall stock sizes.
The ecological effects of urbanization of coastal watersheds: historical increases in nitrogen loads and eutrophication of Waquoit Bay estuaries
Authors: Bowen Jennifer L , Valiela Ivan
Published: April 2011

Historical changes in land use on coastal watersheds have increased rates of land-derived nitrogen loading to estuaries and altered their biogeochemistry and food webs. We used information on human populations and land uses within the watershed of Waquoit Bay, Cape Cod, Massachusetts, U.S.A., to model how nitrogen loads derived from atmospheric deposition, fertilizer use, and wastewater disposal have changed since the 1930s. Nitrogen loading into Waquoit Bay more than doubled between 1938 and 1990. The predominant source of nitrogen added to the bay changed from atmospheric deposition to wastewater disposal during the 1980s, reflecting the increasing urbanization of Cape Cod. Larger nitrogen loads increased nitrogen concentrations in the water, altering the assemblage of primary producers and resulting in eutrophication of the estuary. Biomass of phytoplankton and macroalgae increased, and areal cover of eelgrass (Zostera marina) decreased, with increasing nitrogen load. An increase in nitrogen load from 15 to 30 kg N·ha1·year1 virtually eliminated eelgrass meadows. Land-use changes prompted by urban sprawl can therefore be linked to marked changes in water quality and eutrophication of receiving waters.
Why the Atlantic cod (Gadus morhua) stock off eastern Nova Scotia has not recovered
Authors: Fu Caihong , Mohn Robert , Fanning L Paul
Published: April 2011

An age-structured population dynamics model, incorporating interactions between Atlantic cod (Gadus morhua), the fishery, and the grey seal (Halichoerus grypus) population, was applied to the cod stock off eastern Nova Scotia (Northwest Atlantic Fisheries Organization Divisions 4Vs and 4W, commonly abbreviated to 4VsW), a stock that has dramatically declined since the late 1980s. Mortality was modeled as having three components: fishing mortality (F), seal predation (Mp), and all other sources of natural mortality (M). Specifically, M was assumed to be distinct for immature cod (ages 14; Mi) and mature cod (age 5 and older; Mm), and respective annual variations were estimated. Parameters estimated also included recruitment (cod abundance at age 1; R), F, and Mp. Based on our estimates of F, Mp, and M, it is unlikely that the collapse of the 4VsW cod stock can be attributed to a sudden increase in M; fishing appears to have been the primary cause for the stock's decline. However, after the moratorium on commercial fishing in 1993, increasing Mp and Mm and low R may have contributed to the failure of the 4VsW cod stock to recover.
Littoral water temperature response to experimental shoreline logging around small boreal forest lakes
Authors: Steedman Robert J , Kushneriuk Robert S , France Robert L
Published: April 2011

Shoreline logging did not significantly increase average littoral water temperatures in two small boreal forest lakes in northwestern Ontario, Canada. However, over the early summer monitoring period clearcut shorelines were associated with increases of 12°C in maximum littoral water temperature, and increases of 0.30.6°C in average diurnal temperature range, compared with undisturbed shorelines or shorelines with 30-m shoreline buffer strips. Comparison of simultaneous water temperatures at littoral locations with and without shoreline forest showed that increased temperatures were caused by daytime heating.
Surplus production, variability, and climate change in the great sardine and anchovy fisheries
Authors: Jacobson Larry D , De Oliveira Jose A.A , Barange Manuel , Cisneros-Mata Miguel A , Félix-Uraga Roberto , Hunter John R , Kim Jin Yeong , Matsuura Yasunobu , Ñiquen Miguel , Porteiro Carmela , Rothschild Brian , Sanchez Ramiro P , Serra Rodolfo , Uriarte Andres , Wada Tokio
Published: April 2011

We used fishery and survey data to calculate annual surplus production (ASP) and instantaneous surplus production rates (ISPR) for eight anchovy and nine sardine stocks. In addition, we calculated ASP per unit spawning area for six anchovy and six sardine stocks. Median ASP was highest for stocks with highest median biomass (mostly anchovies), and ASP was typically about 16% of stock biomass. ASP was often negative, more frequently for anchovies (36% of years) than for sardines (17% of years). ISPR was less variable for sardines and autocorrelated for longer-lived stocks (mostly sardines). Strong biomass increases tended to be preceded by short, abrupt increases in ISPR, and declines were pronounced when catches exceeded ASP for 5 years or more. The longest "runs" of positive and negative production were 21 and 4 years for sardine off Japan, 10 and 3 years for sardine off California, 8 and 2 years for anchovy off Peru, and 4 and 3 years for anchovy off California. ISPR is more sensitive to environmental changes than catch, biomass, or ASP and appear to be better for identifying environmentally induced regime shifts. Long time series show evidence of density-dependent effects on ASP in anchovies and sardines, but environmentally induced variation appears to dominate.
Risk aversion in allocating fishing effort in a highly uncertain coastal fishery for pelagic fish, Moluccas, Indonesia
Authors: Oostenbrugge JAE van , Densen WLT van , Machiels M A.M
Published: April 2011

The Ambonese small-scale purse-seine fishery for small pelagic fish, such as scads and mackerels, is characterised by highly variable daily catches. Fishermen involved in this fishery are therefore seriously constrained in optimising the outcome of their fishery through spatial allocation of effort. Spatial patterns in effort allocation were compared with those in catch per unit effort (CPUE), indexed by both catch weight and profit. Average CPUE indexed by catch weight differed between fishing locations by up to 14 times. However, individual fishermen could only detect such large differences after 14 days of exploratory fishing because of the high variability in daily catches. Daily decisions on effort allocation are therefore not based on maximising CPUE but on minimising operational costs and risk. A very high proportion (88%) of the fishing trips were made within 8 km of the home port, although the capacity of the purse seiners allowed for fishing in more productive areas much farther away. A 10- to 20-fold increase in operation costs (travelling and local use rights) when fishing in other areas reinforced this behaviour.
Differences in Cd accumulation among species of the lake-dwelling biomonitor Chaoborus
Authors: Croteau Marie-Noële , Hare Landis , Tessier André
Published: April 2011

We measured substantial differences in Cd accumulation among four species of the phantom midge Chaoborus that were exposed in the laboratory to the same Cd concentration in naturally contaminated prey. The two large-bodied species accumulated more Cd than did the two small-bodied species, in spite of the fact that all species ingested prey at the same rate. To determine why this was the case, we fitted our experimental data to a bioaccumulation model that allowed us to compare the species with respect to their rate constants for growth and Cd efflux, their Cd assimilation efficiency, and their Cd concentrations at steady state. Differences among species were explained mainly by the fact that the small-bodied species assimilated a much lower proportion of the Cd that they ingested with prey ([Formula: see text] 6%) than did the large-bodied species (45 and 58%). A comparison between Cd concentrations measured in Chaoborus species in the field and predictions from the model suggests that differences in Cd concentrations among coexisting Chaoborus species in nature are explained by differences both in the rate at which they assimilate Cd and in their feeding habits.
Cellular and tissular distribution of copper in an intrasedimentary bivalve, the Baltic clam Macoma balthica, originating from a clean or a metal-rich site
Authors: Ballan-Dufrançais C , Jeantet A Y , Geffard A , Amiard J C , Amiard-Triquet C
Published: April 2011

Baltic clams (Macoma balthica) from clean and industrialized areas were exposed to 30 ng Cu·mL1 or 40 ng Cu·mL1 for 13 days. Specimens from the industrialized site accumulated less Cu in their soft tissues, suggesting that those clams living in a metal-rich area are able to limit metal accumulation. Cu and metallothionein-like protein (MTLP) levels were positively correlated in specimens from the industrialized site only, indicating that perhaps living in a polluted area enables them to use this method of detoxification. The contaminated specimens contained Cu-rich microgranules in the basal lamina and intracellular spaces of digestive gland, labial palps, and gills as well as in lysosomes of the digestive gland and in a few hemocytes. The coexistence of S and Cu suggests that sulfur may be the chelating agent. As a consequence of detoxified storage, ultrastructural damage was rarely observed. These Cu deposits, which contributed to the predominance of biochemical insoluble forms shown in the whole soft tissues, are generally considered hardly available to predators, whereas soluble Cu (3538% of total Cu) would most probably be bioavailable.
Summer movement and growth of juvenile anadromous salmonids in small western Washington streams
Authors: Kahler Thomas H , Roni Philip , Quinn Thomas P
Published: April 2011

Movements of juvenile coho salmon (Oncorhynchus kisutch), cutthroat trout (Oncorhynchus clarki clarki), and steelhead trout (Oncorhynchus mykiss) were studied by observations and recapture of marked individuals in three western Washington streams to test the hypotheses that few fish would move, downstream movement would predominate, movers would be initially smaller and grow slower after movement than residents, and habitat quality would influence movement. Contrary to predictions, from 28 to 60% of marked fish moved at least one habitat unit, and immigration of unmarked fish also indicated considerable movement. Upstream movement predominated but the stream with the step-pool/cascade channel type had fewer upstream movers and greater distances moved downstream. Coho movers were not smaller than nonmovers, as predicted based on assumptions that movement results from competitive exclusion. Habitat units that coho left were smaller and shallower but lower in density than units where coho remained. Thus, movement is a common phenomenon rather than an aberration, and may reflect habitat choice rather than territorial eviction. Moreover, movers grew faster than nonmovers, so the "mobile fraction" of the population was not composed of competitively inferior fish but rather individuals that thrived. The phenomenon of small-scale habitat- and growth-related movements should be considered when planning and interpreting studies of juvenile salmonid ecology in streams.
The post-Wisconsinan glacial biogeography of bull trout (Salvelinus confluentus): a multivariate morphometric approach for conservation biology and management
Authors: Haas Gordon R , McPhail J D
Published: April 2011

Canonical correlation analysis (CCA) can quantitatively partition historical and ecological information from morphometric data where these features are otherwise confounded. CCA is applied to sample site locality morphometric data and corresponding sample site locality coordinate data for bull trout. Two vectors result. The first accounts for the maximum morphometric variation correlated to geographic information specified by the locality coordinates. The second represents the remaining less correlated variation. For biogeography, the first vector generates historical hypotheses for Pleistocene glacial refugia and for post-Wisconsinan glacial recolonization patterns and phylogeographic relationships. The second vector infers hypotheses for broad ecological patterns. The historical biogeographic patterns for bull trout suggest recolonization from either two or three glacial refugia and emphasize within-species biodiversity in western North America. These patterns from the Chehalis and Columbia refugia are largely concordant with other analyses based on molecular genetics. The morphometric analysis also suggests the additional possibility of a Nahanni and (or) Bering refugium. The ecological patterns suggest the importance and extent of anadromy and migration within these historical groups and how this may have affected postglacial recolonization, present distributions, and life histories.
Predicting Cyanobacteria dominance in lakes
Authors: Downing John A , Watson Susan B , McCauley Edward
Published: April 2011

A controversial precept of aquatic ecology asserts that low ratios of nitrogen to phosphorus (N:P) lead to noxious and sometimes toxic blooms of Cyanobacteria. Cyanobacteria dominance is a major risk to human and ecosystem health. The stoichiometric control of Cyanobacteria therefore has become central to freshwater resource management. This controversial concept is based on observed Cyanobacteria dominance in lakes with low N:P and the results of lab and field experiments. Here we analyze data from 99 of the temperate zone's most studied lakes and show that this model is flawed. We show that the risk of water quality degradation by Cyanobacteria blooms is more strongly correlated with variation in total P, total N, or standing algae biomass than the ratio of N:P. Risks associated with Cyanobacteria are therefore less associated with N:P ratios than a simple increase in nutrient concentrations and algal biomass.
Effects of solar ultraviolet radiation on epilithic metabolism, and nutrient and community composition in a clear-water boreal lake
Authors: Watkins Elise Marie , Schindler David W , Turner Michael A , Findlay David
Published: April 2011

Stratospheric ozone depletion, climate change, and acidification will increase the exposure of aquatic eco systems to ultraviolet radiation (UVR; 280400 nm). The objective of this study was to determine the ecological effects of ambient UVR exposure on epilithon (algal communities attached to rocky substrata) relative to an artificially reduced UVR environment. UVR exposure was altered in the littoral zone of a boreal lake by selectively filtering segments of the solar spectrum with large acrylic sheets. This 130-day study took place at the Experimental Lakes Area, northwestern Ontario, in 1998. Epilithon were monitored for changes in productivity, biomass, pigment, and nutrient and taxonomic composition. The absence of UVR increased epilithic photosynthetic rates 3746% above epilithon exposed to ambient UVR, increased cellular carbon and nitrogen content, and consequently lowered C:P. UVR effects on algal metabolism were dependent on seasonal trends. Epilithic respiration rates and chlorophyll a concentrations were not significantly different among treatments. A reduction in UV induced taxonomic shifts in epilithon, with diatoms increasingly favoured under low UV conditions. Species richness and diversity were not affected. Overall, the results of this study, considered together with previous research, suggest that the epilithic community is sensitive to changes in the UVR environment of aquatic ecosystems.
Effects of epilimnetic versus metalimnetic fertilization on the phytoplankton and periphyton of a mountain lake with a deep chlorophyll maxima
Authors: Wurtsbaugh Wayne A , Gross Howard P , Budy Phaedra , Luecke Chris
Published: April 2011

Nutrients can load directly to either the epilimnion or metalimnion of lakes via either differential inflow depths of tributaries or intentional fertilization of discrete strata. We evaluated the differential effects of epilimnetic versus metalimnetic nutrient loading using 17-m-deep mesocosms that extended into the deep chlorophyll layer of oligotrophic Pettit Lake in the Sawtooth Mountains of Idaho. Addition of nitrogen plus phosphorus stimulated primary production nearly identically (2.4- to 4-fold on different dates) in both treatments, with the production peaks occurring in the strata where nutrients were added. The metalimnetic fertilization, however, resulted in equal or greater stimulation of chlorophyll a and phytoplankton biovolume than when nutrients were added directly to the epilimnion. Periphyton growth was stimulated 10100 times more by epilimnetic fertilization than by metalimnetic fertilization and diverted nutrients from the planktonic autotrophs. These results suggest that the development of deep chlorophyll layers may be influenced by plunging river inflows that carry nutrients to the metalimnion and that metalimnetic lake fertilization may be useful as a tool for increasing lake productivity while reducing the impact on water quality.
Individual-based yield-per-recruit analysis, with an application to the Atlantic sea scallop, Placopecten magellanicus
Authors: Hart Deborah R
Published: April 2011

There can be considerable variation in fishing mortality risk among individuals in a stock, especially for sedentary or sessile species. An individual-based per-recruit model is proposed that can systematically deal with variability in fishing mortality among recruits. These variations can alter the yield per recruit (YPR) and biomass per recruit (BPR) that would be predicted from conventional theory. Where the YPR curve is concave, standard theory will tend to overestimate YPR, whereas the opposite will be true where the YPR curve is convex. Additionally, variations in fishing mortality among individuals can create a mismatch between conventional metrics of mean fishing mortality and that required to properly apply standard per-recruit theory. The concept of "recruit-weighted" fishing mortality is introduced to deal with this problem. An application of the model to the Atlantic sea scallop, Placopecten magellanicus, is presented that demonstrates that standard per-recruit theory may often misrepresent true YPR and BPR.
Facilitative interactions among aquatic invaders: is an "invasional meltdown" occurring in the Great Lakes?
Authors: Ricciardi Anthony
Published: April 2011

A widely cited hypothesis in ecology is that species-rich communities are less vulnerable to invasion than species-poor ones, owing to competition for limiting resources (the "biotic resistance" model). However, evidence for biotic resistance in aquatic ecosystems is equivocal. Contrary to the view that communities become more resistant to invasion as they accumulate species, the rate of invasion has increased over the past century in areas that have received frequent shipping traffic. Furthermore, introduced species may facilitate, rather than compete with, one another. A review of invasions in the Great Lakes indicates that direct positive (mutualistic and commensal) interactions among introduced species are more common than purely negative (competitive and amensal) interactions. In addition, many exploitative (e.g., predatorprey) interactions appear to be strongly asymmetric in benefiting one invading species at a negligible cost to another. These observations, combined with an increasing invasion rate in the Great Lakes, tentatively support the Simberloff  Von Holle "invasional meltdown" model. The model posits that ecosystems become more easily invaded as the cumulative number of species introductions increases, and that facilitative interactions can exacerbate the impact of invaders. It provides a theoretical argument for substantially reducing the rate of species introductions to the Great Lakes.
Rapid recovery of exhausted adult coho salmon after commercial capture by troll fishing
Authors: Farrell Anthony P , Gallaugher Patricia E , Routledge Richard
Published: April 2011

To reduce mortality in the by-catch of commercial salmon fisheries, techniques are being explored to revive fish before live release and improve survival. By measuring blood and muscle variables, we demonstrated that capture of coho salmon (Oncorhynchus kisutch) by commercial trolling methods resulted in severe exhaustion and stress, e.g., muscle lactate reached 46.1 mmol·kg1while muscle phosphocreatine (PCr) decreased to 6.1 mmol·kg1. Nevertheless, coho salmon recovered rapidly by swimming in a cage alongside the vessel while fishing activity continued. In particular, there were significant increases in muscle glycogen and PCr levels, and a decrease in muscle lactate after two hours. Notably, and in contrast to when exhausted fish are held stationary during recovery, plasma lactate remained low (<4 mmol·L1) during recovery, a phenomenon observed in earlier laboratory studies with rainbow trout (Oncorhynchus mykiss). There was no postcapture delayed mortality after 24 h. Therefore, we have established that postexhaustion activity promotes a rapid recovery in wild salmon and this result might find application in nonretention commercial and recreational fishing.
IV.: ON THE FAUNA OF THE ATLANTIC COAST OF CANADA.: SECOND REPORT.—MALPEQUE, 1903-1904.
Authors: Stafford M.A., Ph. D. J.
Published: April 2011

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V.: ON THE FAUNA OF THE ATLANTIC COAST OF CANADA.: THIRD REPORT—GASPE, 1905-1906
Authors: Stafford M.A., Ph. D. J.
Published: April 2011

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X.: HOLOSOMATOUS ASCIDIANS FROM THE COAST OF WESTERN CANADA.
Authors: Huntsman B.A., M.B. A. G.
Published: April 2011

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VII.: INVESTIGATION OF A DISEASE OF THE HERRING (CLUPEA HARENGUS) IN THE GULF OF ST, LAWRENCE, 1914.
Authors: Cox Ph.D. Philip
Published: April 2011

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XI: List of Fishes collected in 1917 off the Cape Breton coast and the Magdalen Islands.
Authors: Cox Ph.D. Philip
Published: April 2011

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No. 4: SOME PHYSICAL AND CHEMICAL FACTORS INFLUENCING THE DISTRIBUTION OF MARINE FLORA AND FAUNA IN THE STRAIT OF GEORGIA AND ADJACENT WATERS
Authors: CAMERON A. T. , MOUNCE IRENE
Published: April 2011

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No. 6: THE EFFECT OF MARKED CHANGES IN SPECIFIC GRAVITY UPON THE AMOUNT OF PHYTOPLANKTON IN DEPARTURE BAY WATERS
Authors: MOUNCE M.A., M.Sc. IRENE
Published: April 2011

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No. 10: A PRELIMINARY LIST OF BRYOZOA (POLYZOA) FROM THE VANCOUVER ISLAND REGION
Authors: O'DONOGHUE B.A., F.Z.S., F.R.S.C. ELSIE , O'DONOGHUE D.SC. CHAS H.
Published: April 2011

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No. 17: THE LARVAL STAGES AND MEGALOPS OF CANCER AMŒNUS (HERBST)
Authors: CONNOLLY PH.D. C. J.
Published: April 2011

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No. 6: LIMITING FACTORS FOR MARINE ANIMALS.: 3. RELATIVE RESISTANCE TO HIGH TEMPERATURES
Authors: HUNTSMAN A. G. , SPARKS M. I.
Published: April 2011

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No. 16: STUDIES IN THE ECOLOGY OF THE SOCKEYE SALMON (ONCORHYNCHUS NERKA)
Authors: FOERSTER PH.D. R. EARLE
Published: April 2011

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No. 18: A REVIEW OF THE CIRRIPEDIA OF THE COAST OF BRITISH COLUMBIA, WITH GLOSSARY, AND KEY TO GENERA AND SPECIES
Authors: CORNWALL F.G.S. IRA E.
Published: April 2011

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No. 22: TINTINNIDAE FROM THE STRAIT OF GEORGIA, B.C.
Authors: WAILES G. H.
Published: April 2011

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CONDITIONS AFFECTING THE GROWTH OF THE SOFT SHELL CLAM, MYA ARENARIA L.
Authors: WILTON MARGARET H. , WILTON HELEN I.
Published: April 2011

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FACTORS INVOLVED IN THE PRODUCTION OF ANNUAL ZONES IN THE SCALES OF THE COD (GADUS CALLARIAS LINNAEUS)
Authors: DUFF B.A. G. LYMAN
Published: April 2011

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THE SPAWNING AND DEVELOPMENT OF MACKEREL ON THE OUTER COAST OF NOVA SCOTIA
Authors: SPARKS IRVING
Published: April 2011

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SPAWNING PERIODICITY AND EMBRYONIC DEATH RATE OF ENCHELYOPUS CIMBRIUS (L.) IN PASSAMAQUODDY BAY
Authors: BATTLE HELEN I.
Published: April 2011

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SOME CISCOES OR LAKE HERRINGS OF WESTERN CANADA
Authors: DYMOND J. R. , PRITCHARD A. L.
Published: April 2011

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SYMBIOSIS OF BEROE AND A FLAGELLATE
Authors: BERKELEY C.
Published: April 2011

Beroe abyssicola Mortensen is a ctenophore occurring in the strait of Georgia, found only at depths of 150 fathoms or more, characterised by the possession of a deep red lining to the stomodoeum, which is due to a symbiotic flagellate present in very large numbers in the cells immediately beneath the epithelial layer. The organism is minute, never exceeding 2 μ in diameter.Though highly coloured, it lives in an environment to which practically no sunlight penetrates, thus resembling the green organism inhabiting the cells of the intestinal lining of the Chaetopteridae previously described by the author.
STUDIES ON THE PHOTOSYNTHESIS OF MARINE ALGAE NO.1: PHOTOSYNTHETIC RATES OF ENTEROMORPHA LINZA, PORPHYRA UMBILICALIS AND DELESSERIA SINUOSA IN RED, GREEN AND BLUE LIGHT
Authors: KLUGH A. BROOKER
Published: April 2011

Pieces of the fronds of Enteromorpha linza, a green alga, growing just beneath the surface of the sea, of Porphyra umbilicalis, a red alga, of which the fronds of brownish-red colour which were growing on the side of a dock at half-tide level were selected, and of Delesseria sinuosa, a bright magenta-red alga from a depth of 18 metres in Passamaquoddy bay, were placed in vials of sea water (previously brought to pH 7 by the addition of KH2PO4), behind Corning red, green and blue filters, which had been brought to equal intensity in the photosynthetically active part of the spectrum, and exposed to sunshine. The gain in pH, due to the using up of CO2, was read at the end of 10 minute periods with a B.D.H. capillator set, and the photosynthetic rates for each species were determined by dividing the gain in pH (in hundredths of a unit) by the time. The photosynthetic rates of these three species in the different regions of the spectrum were very different, those of E. linza being red = 1.80; green = 0.16 and blue = 1.16, of P. umbilicalis red = 2.46; green and blue = 1.65, and of D. sinuosa red = 1.35; green = 1.25 and blue = 1.05. These data fit in very well with the transmission coefficients for red, green and blue light in the bay of Fundy at the place where the experiments were carried on, as green light penetrates best, blue next and red least.
POLYCHAETOUS ANNELIDS FROM THE NANAIMO DISTRICT PART 5. AMMOCHARIDAE TO MYZOSTOMIDAE: WITH AN APPENDIX ON SOME PELAGIC FORMS FROM THE STRAITS OF GEORGIA AND THE WEST COAST OF VANCOUVER ISLAND
Authors: BERKELEY EDITH
Published: April 2011

This last instalment of the list (of polychaetes collected in the Nanaimo region), comprises the families Ammocharidae, Arenicolidae, Scalibregmidae, Chlorhamidae, Sternaspidae, Sabellidae, Serpulidae, Sabellariidae, and Myzostomidae. A single new species, Branchiomma burrardum, is described. Some pelagic forms from the region and from the west coast of Vancouver island are listed in the appendix.
SPAWNING HABITS AND FRY OF THE CISCO (LEUCICHTHYS ARTEDI) IN LAKE ONTARIO
Authors: PRITCHARD ANDREW L.
Published: April 2011

The spawning habits of the cisco (Leucichthys artedi) and the fry were studied in the bay of Quinte, Lake Ontario. It was found that the cisco spawns during the last two weeks of November and in December. The eggs are deposited in crevices of the rocks in water from two and a half to three metres deep. They hatch in late April and early May, the period of incubation depending on temperature and other conditions. The fry are found schooling with the whitefish in shallow, protected bays until they are about a month old, when they disappear. Fry commence to feed when about ten days old, their food consisting chiefly of algae, copepods and cladocerans.
THE MIGRATIONS OF HADDOCK AND THE INTERRELATIONSHIPS OF HADDOCK POPULATIONS IN NORTH AMERICAN WATERS
Authors: NEEDLER A. W. H.
Published: April 2011

The haddock's range in North American waters is divided by the Fundian and Laurentian channels (both over 185 metres deep) into the "New England", "Nova Scotian" and "Newfoundland" regions. Marking experiments and comparisons of the age composition of stocks and of the growth rates show that there is practically no interchange between the first two. To the haddock, which are bottom-loving fish and never abundant below 185 metres (100 fathoms), the channels are barriers producing three divisions of the population corresponding to the divisions of the shallow water area. Seasonal migrations are shown in both the New England and Nova Scotian regions. Haddock withdraw in winter from areas north of Halifax and large haddock migrate into the gulf of St. Lawrence each summer. In midwinter the catches are chiefly below 70 metres (40 fathoms); in spring and early summer haddock appear well inshore in shallow water; in late summer they withdraw to deeper water; in late autumn they are caught in a great range of depths leaving the shallower parts as winter approaches. Both horizontal and vertical movements are correlated with temperatures—haddock avoiding those near 0 °C. and 11 °C. and preferring intermediate temperatures. Prior to maturity the haddock are relatively stationary becoming increasingly active in seasonal migration thereafter and changing their distribution—e.g., older haddock accumulate in the eastern part of the Nova Scotian region. The New England and Nova Scotian populations are groups of more or less distinct smaller units.
THE OCCURRENCE OF CREATINE IN THE MUSCLE, BLOOD, AND URINE OF THE DOGFISH, SQUALUS SUCKLII
Authors: WHITE F. D.
Published: April 2011

Extract from the caudal muscle of dogfish was analysed for inorganic and labile phosphorus, and from the latter value the content of creatine in combination as phosphocreatine was calculated. As this only accounted for about 10 per cent. of the total creatine, reasons are advanced for the suggestion that the greater part of the creatine in muscle is present in some other form of combination.The creatine and creatinine content of the blood of a number of dogfish was found to have mean values of 7.1 mg. and 1.8 mg. respectively per 100 cc. This is similar to other reported analyses and indicates that elasmobranch blood does not differ in respect to its content of these constituents from the blood of other vertebrates.Ten samples of urine collected from four dogfish gave an average rate of excretion of 1.4 cc. per kg. weight per hour. These samples were found to contain relatively large amounts of creatine, but little or no creatinine.