Conception Bay Research Articles

Hope and Deception in Conception Bay: Merchant-Settler Relations in Newfoundland 1785-1855

Hope and Deception in Conception Bay: Merchant-Settler Relations in Newfoundland 1785-1855

Microbial processes in cold oceans. I. Relationship between temperature and bacterial growth rate

Despite the obvious relevance of the high latitude oceans to models and budgets of biogenic carbon, the seasonal patterns of energy flow through the lower food web in this region are poorly understood. It has been suggested that, in high latitude and cold oceans, the rates of bacterial metabolism and growth are low and are depressed to a much greater degree than those of co-occurring phytoplankton and metazoan heterotrophs. The low-temperature suppression of bacterial growth would reduce microbial food web activity, bacteria would consume and recycle less primary production and more phytoplankton carbon would be available to metazoan grazers. The implications of this scenario for models of oceanic carbon flow are profound. In this paper, we present an analysis of 66 published studies on temperature and growth rate for bacteria from the World Ocean, including polar regions, and examine the results of a field investigation of bacterioplankton growth in seasonally cold Newfoundland (eastern Canada) coastal waters. Based upon the analysis of published data, where approximately 50 % of the observations were from environments less than or equal to 4 degrees C, we report a weak (r(2) - 0.058, n = 231) relationship between specific growth rate (SGR) and temperature with a Q(10) = 1.5. The mean (0.39 to 0.41 d(-1)) and median (0.25 to 0.29 d(-1)) SGR of bacteria from cold (less than or equal to 4 degrees C) and warm (>4 degrees C) waters were not significantly different. For both the published data as well as for the field study in Conception Bay, Newfoundland, the SGR was significantly greater (p < 0.01) when computed from empirical thymidine conversion factors than from theoretical or literature derived thymidine conversion factors. Our analysis suggests that the growth rates of bacterioplankton from cold and temperate oceans are similar at their respective ambient temperatures, when the appropriate conversion factors are used to compute growth. We propose that bacteria-based food webs and microbial trophic pathways are as important in overall energy and material cycling in high latitude oceans as they are at lower latitudes.

Hope and deception in Conception Bay: merchant-settler relations in Newfoundland, 1785-1855

Hope and deception in Conception Bay: merchant-settler relations in Newfoundland, 1785-1855

The Role of the Death-Bed Narrative in the Conception Bay Revival of 1768-69

The Role of the Death-Bed Narrative in the Conception Bay Revival of 1768-69

Variations in the contribution of transport to changes in planktonic animal abundance: a study of the flux of fish larvae in Conception Bay, Newfoundland

We investigated the magnitude of short-term variations in the flux of several species of fish larvae in Conception Bay, Newfoundland, determined the contribution of these fluxes to changes in the abundance of these species, and assessed the factors that may be causing the variations in these fluxes. The net effect of transport ranged from a daily influx of 5.8% to a daily efflux of 6.2% from the population. Short-term variations in transport were associated with variations in wind stress. The contribution of transport to variations in population abundance ranged from 12 to more than 75% of the average daily rate of change in numbers for the different species. The contribution of physical processes to estimated mortality rates is variable and can have a significant impact on the investigation and interpretation of potential biological processes (e.g., predation and starvation) influencing the survival of larval fish. We predicted that the average correction to the instantaneous mortality rate due to advection and diffusion should be proportional to A−1/2, where A is the area of system under study. This highlights the susceptibility of small systems to estimation error of mortality rates caused by short-term variations in physical forcing.

Observations on the Occurrence of Hematodinium sp. (Dinoflagellata: Syndinidae), the Causative Agent of Bitter Crab Disease in Newfoundland Snow Crab (Chionoecetes opilio)

We describe the first occurrence in Atlantic Canada waters of "bitter crab disease" in the snow crab, Chionoecetes opilio. The condition is caused by a parasitic dinoflagellate, Hematodinium sp. Male crabs held in captivity harbored vegetative, prespore, and dinospore stages. Incidence of the disease was low (= <0.11%) off the eastern and northeastern coasts of Newfoundland in 1992-1993, except in Conception Bay, where 3.7% of 135 crabs examined were infected. The significance of Hematodinium sp. to snow crab populations in Newfoundland and to the commercial fishery is not yet clear, but it is prudent to monitor this parasite which has caused local depletion of Tanner crab populations in Alaska.

The circulation and hydrography of conception bay, Newfoundland

Abstract The hydrography and circulation of Conception Bay (Newfoundland) are described based on hydrographic, current‐meter and drifter data collected over four years (1988–1991). The seasonal cycles of temperature (‐1.6 to 13–17°C) and salinity (31–32.5) in the bay closely follow those on the adjacent shelf. Exchange of bottom water was observed in April 1989. Deepwater exchange was observed from late fall to early winter of 1989–90. Tidal currents are weak, 1–2 cm s‐1 for the M2 and K1 constituents. Observed Eulerian mean currents (<3 cm s‐1) are smaller than the standard deviation (1–11 cm s‐1); however, there is a persistent outflowing current of 10 to 20 cm s‐1 within 2 km of the shoreline on the eastern side of the outer bay. The Lagrangian correlation length scale is from 4 to 10 km, in agreement with the weak coherence squared (≤0.4) found between the fixed current‐meter sites separated by greater than 4–5 km. The variable currents (up to 20 cm s‐1) tend to be cyclonic. Cyclonic eddies were obser...

THE MARINE MIXOTROPH DINOBRYON BALTICUM (CHRYSOPHYCEAE): PHAGOTROPHY AND SURVIVAL IN A COLD OCEAN1

ABSTRACT The marine chrysophyte Dinobryon balticum (Schzütt) Lemm. was one of the dominant members of the phytoplankton community (1.8×103 cells‐L−1) in June and July in Conception Bay, Newfoundland. Dinobryon balticum colonies were common only in samples from June and July. The cells were concentrated at 5 m (X±SD=1.11±4 × 105 cells.L−1) and at 40 m (3.32±2×104.L−1) depths. Colonies were composed of up to 560 cells with a mean (±SD) colony size of 10 ± 1 cells at 5 m and 40 ± 8 cells at 40 m. Fluorescent latex bead‐uptake experiments conducted with field samples indicated that this marine species was capable of phagotrophy and that twice as many Dinobryon cells were ingesting beads at 40 m than at 5 m, although the ingestion rates for those cells actively ingesting beads were similar at both depths. This chrysophyte was found in association with bacteria‐and nutrient‐rich microhabitats of microaggregates and fecal pellets. The cells and colonies observed in this study appeared to be healthy, as demonstrated by their appearance and their ability to ingest beads.

Plasma sex steroid profiles and the seasonal reproductive cycle in male and female winter flounder, Pleuronectes americanus

The pattern of seasonal gonadal development and variations in plasma sex steroids were investigated in adult male and female winter flounder, Pleuronectes americanus (Walbaum), from Conception Bay Newfoundland beginning August 1987 to December 1988. The winter flounder reproductive cycle can be divided into five consecutive phases of relative reproductive activity including: (1) rapid gonadal recrudescence in the fall (August–December); (2) continued slow gondadal growth in females, or maintenance of the well developed gonads in males, during the winter (December–February); (3) a prespawning phase of gonadal maintenance in the spring (March–April); (4) spawning early in the summer (May–June) after the female gonads reach peak weight; and (5) the summer postspawned period (June–August) when the gonads remain regressed. Female gonadal recrudescence in August is characterized by small increases in plasma estrogen levels and recruitment of small oocytes (≥150 μm) into yolk accumulation. For the winter months, estradiol-17 β levels in the plasma remain stable, approximately 15 ng ml-1, until rising again together with testosterone to peak hormone levels just prior to spawning in conjunction with the highest seasonal values for the gonadosomatic index (GSI) and oocyte diameter. After spawning, the ovaries are regressed and sex steroids in the plasma fall to very low levels. Rapid seasonal recrudescence of the gonads in males is evident from rising GSI values, which reach a maximum in October, and from substantial early seasonal increases in plasma testosterone and 11-ketotestosterone. Afterwards, although GSI values subsequently decline presumably reflecting the process of spermiogenesis and/or onset of spermiation in some males, the testes remain relatively well developed with the presence of sperm throughout the spawning season. As the proportion of spermiating males increases, the plasma levels of the androgenic steroid hormones rise to peak circulating levels from April to June. At the end of the summer reproductive season, the testes of post-spawned males become regressed and plasma testosterone and 11-ketotestosterone levels fall, reaching the lowest seasonal values.

Factors influencing the spatio-temporal occurrence of fish eggs and larvae in a northern, physically dynamic coastal environment

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 122:73-92 (1995) - doi:10.3354/meps122073 Factors influencing the spatio-temporal occurrence of fish eggs and larvae in a northern, physically dynamic coastal environment Laprise R, Pepin P Distribution patterns, abundance and species composition of the assemblages of fish eggs and larvae in Conception Bay, Newfoundland, Canada, during the early summers of 1990 and 1991 are described. Several species appear to use Conception Bay as a spawning ground. Interannual and seasonal differences in both species composition and abundance in the bay appear to be associated with differences in environmental conditions, particularly with temperature. Both egg and larval abundances were lower by an order of magnitude in 1991 corresponding to the coldest and less saline waters. Temperature and wind were the environmental factors most associated with the spatial distribution of eggs. In both years, highest abundances of all species were usually found at the head and the eastern side of the bay, corresponding to the warmest waters under dominant westerly winds. On one occasion, greatest abundances and warmer waters were found on the western side of the bay, concomitant with a southerly wind episode. Clustering samples by their relative species composition revealed well-defined assemblages of fish larvae. The variability in relative species composition was strongly associated with the physico-chemical conditions of the surface layer and was consistent with patterns of seasonal successions observed in other ecosystems. We propose that temperature is the principal factor controlling spatio-temporal occurrence of fish eggs and larvae in Conception Bay and, most probably, in coastal waters of Newfoundland and Labrador, Canada. This association may be critical in ecosystems characterized by an extremely short growing season. Conception Bay may play an important role in the early-life history of fish inhabiting the northeast Newfoundland/Labrador shelf. Even if a smaller proportion of fish reproduced in the coastal region, their offspring may contribute significantly to the number of individuals recruiting to the population if growth and survival are considerably higher in coastal areas than in offshore areas due to the presence of more favourable habitats for early-life stages of fish. Ichthyoplankton · Diversity · Habitat · Environmental variability · Strategy · Recruitment · Atlantic Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 122. Publication date: June 15, 1995 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1995 Inter-Research.

Unsaturated hydrocarbons in muscle and hepatopancreas of two crab species, Chionoecetes opilio and Hyas coarctatus

Polycyclic aromatic hydrocarbon (PAH) contaminants and biogenic unsaturated hydrocarbons were identified in muscle and hepatopancreas of two crab species, collected nearshore and offshore the island of Newfoundland. A correlation was made between the compounds present in hepatopancreas and in surface sediments collected from Conception Bay, Newfoundland. The bioaccumulation of unsaturated compounds differed slightly with species, while a large variation was noticed between tissues. Relatively greater levels of fluorescing compounds (PAC) were present in hepatopancreas than in muscle of the spider crab ( Hyas coarctatus) or snow crab ( Chionoecetes opilio), while a larger number of PAH was also present in that tissue. The unsaturated hydrocarbons fraction separated from the hepatopancreas extracts was quantified in terms of gravimetry, by ultraviolet/fluorescence (uv/f, four standards), gas chromatography-mass spectrometry (GC-MS) analysis of a series of 25 PAC (GC-MS-SIM), as well as by the analysis of the predominant compounds (GC-MS-TIC). Results obtained by gravimetry were highest (20 μg g −1, dry wt), levels of total fluorescing compounds (uv/f, 1.1 μg g −1, in terms of chrysene units), of four unsaturated biogenic hydrocarbons (< 10 μg g −1) and of detectable parental and alkylated PAH (0.67 μg g −1) were relatively lower. As could be expected, these various concentrations in hepatopancreas samples were not equivalent, but reasonably complementary.

Determination of the [formula omitted] ratios of individual PAH from environmental samples: can PAH sources be apportioned?

Compound-specific carbon isotope analysis was performed on polycyclic aromatic hydrocarbons (PAH) isolated from environmental samples. Analysis of δ 13C of individual PAH standards, including isomeric parental PAH, can be accomplished with a precision of 0.2–0.3%. In environmental samples, the precision and accuracy of similar δ 13C determinations are matrix-dependent, due to limitations imposed by coelution and the presence of an unresolved complex mixture (UCM). For samples of varying UCM the maximum deviations from the mean values ranged from 0.1 to 0.4% for well separated compounds and from 0.3 to 1.1% for high-molecular weight coeluting isomers. Allowing for these analytical limitations, isotopic characterization was performed for parental PAH compounds in primary and secondary sources and estuarine sediment materials. The potential of this technique for source apportionment of PAH was demonstrated using sediments from St John's Harbour and Conception Bay (Newfoundland). Additional experiments were conducted to evaluate whether the isotopic integrity of PAH was maintained after vaporization, photolytic decomposition and microbial degradation. To date, our results indicate that no significant isotopic fractionation accompanies these types of weathering reactions for the investigated 2-, 3-, 4- and 5-ring parental PAH.

Advection–Diffusion Modelling of Larval Capelin (Mallotus villosus) Dispersion in Conception Bay, Newfoundland

A numerical model was used to determine the residence time of capelin (Mallotus villosus) larvae in Conception Bay, Newfoundland. The larvae were observed in the surface mixed layer of the Bay following release from beaches in June–July in order to examine how they move outside the Bay and what physical factors influence their rate of transport. A diagnostic model of Conception Bay provides a fixed velocity field which drives an advection–diffusion model applied to capelin larval dispersal from the Bay. The model was run for different periods to explore dependence of the residence time on different conditions during the period 1989–90. Model results showed that the residence time depends on the release location of the larvae in the Bay. While the residence time of the larvae does vary, we estimate it to be roughly 30 d for larvae released from the head of the Bay. Residence times are much shorter for larvae near the mouth of the Bay.

MOLT INDICATORS AND GROWTH PER MOLT FOR MALE SNOW CRABS (CHIONOECETES OPILIO)

ABSTRACT Examination of mouth parts is a standard method for determining the position in the molt cycle of individual male snow crabs. We showed that the color of the carapace can also be used to determine whether a crab is about to molt. A third, destructive, method is to tear off the dorsal carapace and look for the presence of a second carapace. During a bottom trawl survey in April 1991 in Conception Bay, Newfoundland, we found that green carapace color and a well-developed second carapace were strongly correlated and each was strongly associated with mouthpart classification D, or above. During a subsequent trap survey in May 1991, we found crabs with the normal reddish coloration that had seemingly partially formed second carapaces and mouthparts in the C or D0 stage. However, further work is necessary to describe and validate the early stages of carapace formation. We concluded that the collection of crabs with a green carapace is a viable way to obtain crabs for growth studies, because they will molt in the near future, thus minimizing effects of captivity. We collected 79 green crabs and maintained them in the laboratory until they molted. All but one molted within 24 days of capture. Growth per molt was similar to that estimated for another Newfoundland snow crab population, based on the same approach, but was greater than earlier estimates derived from longer-term laboratory studies.

The Local and Nonlocal Response of Conception Bay to Wind Forcing

Abstract In this paper the response of Conception Bay to wind forcing is discussed. Current meter and thermistor chain observations are analysed and compared with output from a reduced-gravity numerical model. The model incorporates realistic coastal geometry and is driven by wind stress calculated from observed winds. Moorings were deployed in the bay during 1989 and 1990. In 1990 the moorings were placed within the coastal waveguide around the head of the bay and show that southwesterly winds generate an upwelling event on the western side that moves around the head of the bay and is suggestive of Kelvin wave propagation. Data analysis shows that the thermocline response is strongly coherent between each mooring at periods of 2–10 days, and winds measured at a nearby station are found to be strongly coherent with the observed temperature fluctuations. Two versions of the reduced-gravity model are applied—one models Conception Bay alone and ignores “upstream” influences and another includes neighboring T...

A Diagnostic Coastal Circulation Model with Application to Conception Bay, Newfoundland

Abstract A diagnostic circulation model is developed for application to coastal regions. The three-dimensional velocity field can be calculated from a specified density field and wind-stress distribution provided transport is given on boundaries where f/H contours enter the model domain (here f is the Coriolis parameter and H is the ocean depth). The model is an extension of that of Mellor. It includes the effect of vertical mixing and bottom friction and avoids explicit calculation of the JEBAR (joint effect of baroclinicity and relief) term, which can be noisy when a realistic density field is combined with realistic topography. The model can also be used in regions of closed f/H contours. An application of the model to Conception Bay, Newfoundland, illustrates the case of calculation and yields comparisons with the more classical technique of dynamic height analysis.

An Appraisal of the Size-Dependent Mortality Hypothesis for Larval Fish: Comparison of a Multispecies Study with an Empirical Review

This study presents an assessment of the size-dependent mortality hypothesis for larval fish from a multispecies survey of Conception Bay, Newfoundland, Canada. Mortality rates are estimated using a length-based method (per millimetre). The results from this survey are consistent with previous studies which indicate that losses decrease with increasing size of fish. However, for each species within this survey, mortality rates are constant. Comparison of mortality rates within species among surveys indicates that as the range of size categories sampled increases, the estimated mortality rates decrease, despite evidence of adequate fit to the length-based model. The findings indicate that previous relationships between size or stage and mortality of larval fish should be reevaluated. Length-based methodology used to estimate mortality rates of larval fish appears to provide biased estimates of this vital characteristic. It is suggested that using size as a proxy for biological age (i.e., assuming a constant growth rate) may be an invalid assumption. Future surveys will need to provide accurate information about the age structure of larvae sampled in order to properly estimate mortality rates.

Diurnal Feeding of Juvenile Cod (Gadus moruha) which Migrate into Shallow Water at Night in Eastern Newfoundland

In Bonavista Bay, Newfoundland, juvenile cod (Gadus morhua) (age-group-0 and -1) were found to move into shallow water at night, where they mostly rested near the bottom. This nocturnal inshore migration was not associated with feeding, as stomach contents data suggested that feeding takes place mainly during the day, with little or no feeding at night. Most prey were planktonic, even in age-group-1 cod. This contrasted with earlier studies in Conception Bay, Newfoundland where age-group-1 cod were mainly obtaining benthic prey. These results suggested that juvenile cod predation on benthic invertebrates was likely to be patchy in space and time. Results are discussed in view of previous knowledge of the dietary and activity patterns of juvenile cod from elsewhere.

Bacterial Growth in the Cold: Evidence for an Enhanced Substrate Requirement

Growth responses and biovolume changes for four facultatively psychrophilic bacterial isolates from Conception Bay, Newfoundland, and the Arctic Ocean were examined at temperatures from - 1.5 to 35 degrees C, with substrate concentrations of 0.15, 1.5, and 1,500 mg of proteose peptone-yeast extract per liter. For two cultures, growth in 0.1, 1.0, and 1,000 mg of proline per liter was also examined. At 10 to 15 degrees C and above, growth rates showed no marked effect of substrate concentration, while at - 1.5 and 0 degrees C, there was an increasing requirement for organic nutrients, with generation times in low-nutrient media that were two to three times longer than in high-nutrient media. Biovolume showed a clear dependence on substrate concentration and quality; the largest cells were in the highest-nutrient media. Biovolume was also affected by temperature; the largest cells were found at the lowest temperatures. These data have implications for both food web structure and carbon flow in cold waters and for the effects of global climate change, since the change in growth rate is most dramatic at the lowest temperatures.

Trypanosome occurrence and prevalence in the marine leech Johanssonia arctica and its host preferences in the northwestern Atlantic Ocean

In this study, the distribution, abundance, host selection, and prevalence of trypanosomes in the marine leech Johanssonia arctica in the northwestern Atlantic were investigated. This leech is widely distributed and is encountered more often in the Labrador – northeastern Newfoundland area, especially at depths of 165 m or more, where water temperatures of about 0 °C prevail. It rarely occurs south and west of Newfoundland, where warmer bottom temperatures occur. The highest prevalence of the trypanosome (Trypanosoma murmanensis) infection was found in leeches collected from a depth of 165 m in summer off the Labrador and north and east Newfoundland coasts in the largest leeches (~25 mm). Samples taken at 3- to 5-month intervals in Conception Bay over a 7-year period showed that prevalence of the trypanosome infection is also greater in summer–autumn than during winter. The leeches sampled had fed predominantly on pleuronectiform (flatfish) rather than perciform or gadiform fish, and rarely on elasmobranchs. High prevalences of T. murmanensis in fish coincide with the abundance of J. arctica in several areas of the northwestern Atlantic. Since six other species of marine leeches apparently do not acquire trypanosome infections after feeding on infected fish, J. arctica is probably the major vector of the parasite in the northwestern Atlantic north of latitude 45°N.