Canadian Coastal Waters Research Articles

Marine and freshwater centrohelid heliozoans (Haptista: Centroplasthelida) in Canada, including taxonomic revisions and descriptions of 22 new species and subspecies

Canadian coastal waters of the Pacific Ocean and the Atlantic Ocean as well as inland freshwater habitats in Ontario were sampled for centrohelid heliozoans (free-living heterotrophic single-celled organisms) over a period of nearly five decades. More than 60 species and subspecies were revealed, including 1 Triangulopteris, 1 Raphidocystis, 2 Pseudoraphidocystis, 3 Raineriophrys, 4 Pseudoraphidiophrys, 12 Choanocystis, 15 Pterocystis, and 25 Acanthocystis taxa. Of these, 22 were officially named and described as new to science based primarily on the morphology of the siliceous scales that cover the cell. New species were compared with images and/or descriptions of close “relatives” to validate their new species assignments. New data on five species of Acanthocystis and one species of Choanocystis required revisions of their descriptive taxonomy that in some cases resulted in the splitting off of separate species or subspecies. Very little can be concluded about global distribution of centrohelid heliozoans, owing to the paucity of records. For many of the taxa reported here, previous records consist of just one or two findings from other parts of the world. One example is Choanocystis antarctica Tikhonenkov and Mylnikov, 2011 that was previously known only from Antarctic seawater, but is reported here from an Ontario softwater lake.

A temporal assessment of risk of non-indigenous species introduction by ballast water to Canadian coastal waters based on environmental similarity

The environmental similarity scores between source and recipient locations are essential in ballast water risk assessment (BWRA) models used to estimate the potential for non-indigenous species (NIS) introduction, survival, and establishment, and to guide management strategies aiming to minimize biodiversity loss and economic impacts. Previous BWRA models incorporate annual-scale environmental data, which may overlook seasonal variability. In this study, temporal variation in sea surface temperature and salinity data were examined at global ports, and the influence of this variation on environmental distance calculations (and corresponding risk of NIS) was examined for ballast water discharges in Canada by comparing outputs from monthly and annual scale assessments in a BWRA model. Except for some outliers in the Pacific region, the environmental distances based on monthly scale data generally become smaller in all regions, demonstrating that the model using annual decadal average environmental data to inform environmental matching can underestimate risk of NIS survival and establishment in comparison to monthly data. The results of this study suggest future evaluations incorporating the date of ballast water uptake and discharge can provide a more sensitive assessment of risk reflecting seasonal variability compared to an annual average risk model.

Evaluation of a new screening-level risk assessment tool applied to non-indigenous marine invertebrates in Canadian coastal waters

Screening-level risk assessment tools for non-indigenous species are useful to inform management and policy decisions. While a number of tools have been developed to evaluate the risk of introductions in terrestrial and freshwater environments, only one tool is available for marine invertebrates [Marine Invertebrate Invasiveness Scoring Kit (MI-ISK)] and it has not been calibrated or evaluated previously. This paper introduces the Canadian Marine Invasive Screening Tool (CMIST), a tool based on a series of questions related to the sequence of events in the invasion process. We assessed the performance of both CMIST and MI-ISK using 60 species/ecosystem combinations of non-indigenous marine invertebrate species known to have been introduced to three Canadian marine ecoregions. Assessment scores were compared to the results of an expert opinion survey about the level of ecological risk posed by these species in these ecoregions. In addition, a simple way to quantify uncertainty and compute confidence limits surrounding expert evaluations and CMIST scores is presented; the technique could be incorporated into other existing tools. The risk scores returned by the two tools generally were similar, had comparable levels of inter-assessor variability, and correlated well with the results of the expert opinion survey for two of the three ecoregions. In the third ecoregion, we believe the lack of highly problematic species and greater uncertainty (linked to less reliable information) contributed to the weaker correlation. For all ecoregions, CMIST scores were more strongly correlated with expert opinion scores when compared to MI-ISK scores. Finally, we demonstrate how CMIST can be used for new incursions; for each ecoregion we scored 15 additional species not yet introduced and compared these scores with those of species already present. Overall CMIST is a promising screening-level tool; it distinguishes between elements of invasion risk (likelihood and impact), has fewer questions to score than similar tools, and could easily be adapted for other taxa.

Thermal Fronts Atlas of Canadian Coastal Waters

Oceanic fronts are often associated with enhanced biological activity. Depending on their generation mechanism, they are often linked to specific geographical areas. Here we use 25 years of high-resolution satellite sea surface temperature (SST) daily images to generate maps of SST fronts over Canadian coastal waters. Results show that fronts are ubiquitous features, but some fronts are more persistent than others. We confirmed the location of previously known major fronts, but some new persistent frontal areas were also detected as a result of the use of high-resolution (1.1 km) data and a methodology adapted to detect smaller-scale frontal features. Results also show that some of the frontal areas are associated with enhanced phytoplankton biomass or higher trophic level organisms (whales and birds) confirming the ecological importance of this physical process.

Temperature‐mediated survival, development and hatching variation of Pacific cod Gadus macrocephalus eggs

Laboratory-validated data on the survival, development and hatching responses of fertilized Pacific cod Gadus macrocephalus eggs from the northern Japan stock were determined through an incubation experiment. The optimum temperature for survival until hatching ranged from 4 to 8°C. No significant difference in development rates was found between the populations from Mutsu Bay, Japan, and western Canadian coastal waters even though the samples may belong to different G. macrocephalus stocks. Gadus macrocephalus larvae hatched asynchronously from egg batches despite incubation under the same environment during their development. Both incubation temperature and temperature-mediated hatch rank affect size and yolk reserve. These data suggest that variations in water temperatures within an ecological range markedly influence the development rates, survival and hatching of the eggs, as well as the stage at hatch larvae of G. macrocephalus. Asynchronous hatching and the production of offspring with variable sizes and yolk reserves are considered evolutionary bet-hedging strategies that enable the species to maximize their likelihood of survival in an environment with variable temperatures.

Atmospheric control of sea-ice thickness variability in the Amundsen Gulf, Canadian Beaufort Sea, and over the Labrador Shelf

AbstractSea-ice thicknesses observed in Canadian coastal waters with helicopter-borne electromagnetic–laser sensors show large interannual variability caused by atmospheric fluctuations in two years for two areas where surveys were repeated, one in the Amundsen Gulf of the Canadian Beaufort Sea and one over the Labrador Shelf. For the Amundsen Gulf, the bimodal ice thickness peaks shifted by 40 cm to thinner thicknesses for the warmer winter of 2008 compared with 2004. The thinner ice in 2008 can be explained partially by reduced thermodynamic ice growth during the warmer winter of 2008. In addition, winds from the east were more persistent throughout the winter of 2008, increasing ice export from the Amundsen Gulf and thereby creating open-water areas where new ice growth in late winter produced the thinner ice classes. For the Labrador Shelf, the mean ice thicknesses of the warmer winter of 2011 (0.71 m) were much less than those of the near-normal winter of 2009 (1.60 m). Again the difference can be explained by the fact that along the entire Labrador Shelf the winter of 2011 was much warmer, reducing ice growth and resulting in thinner ice locally and thinner ice being transported into the survey region from northern latitudes. In addition, northwesterly winds occurred less frequently during the winter of 2011, reducing the transport of relatively thicker ice into the survey area from northern latitudes.

The price of lice

Wild salmon stocks in Canadian coastal waters are being severely affected by parasites from fish farms. So intense are these infestations that some populations of salmon are at risk of extinction.

SeaWiFS global composite images show significant features of Canadian waters for 1997–2001

The sea-viewing wide field-of-view sensor (SeaWiFS) is designed to image the spectral water-leaving radiance in ocean and coastal waters with timing and spatial resolution suitable for a range of marine and coastal environmental monitoring. The monthly composite time series compiled by the National Aeronautics and Space Administration (NASA) provides a valuable data source that deserves to be more widely known and applied in regional studies. This paper presents examples of time series of Canadian coastal waters compiled for each month from September 1997 to December 2001 for the west coast of Canada (British Columbia), the Great Lakes, and the east coast of Canada (Gulf of St. Lawrence and Newfoundland – Grand Banks). The time series show the seasonal and interannual variations of phytoplankton surface concentration and the occurrence of major bright plankton blooms on the B.C. coast, in the Gulf of St. Lawrence, and on the Grand Banks. In addition, "bright-water" events are shown in Lake Erie and Lake Michigan. Many cases also occur where the reflectance of large areas of water is increased by sediment from rivers or resuspended bottom sediment. The data show the value of a consistent time series of satellite data, both for single-band radiance products and for the derived chlorophyll data. In particular, the water brightness data show significant events that do not appear to have been reported in the scientific literature.

An assessment of validation techniques for estimating chlorophyll-a concentration from airborne multispectral imagery

Accurate estimates of chlorophyll-a levels in coastal waters are required for the assessment of waters potentially subject to eutrophication. Traditional laboratory analysis of water samples does not offer the required spatial or temporal density of sampling. Remote sensing methods have been suggested as a more appropriate representation of the variability in chlorophyll a concentration encountered in UK coastal waters. This paper examines the use of two established techniques for the calibration of airborne multispectral imagery to determine chlorophyll-a concentration: the blue/green ratio and Fluorescence Line Height methods. These methods have been developed for use in oceanic or Canadian coastal waters. The errors incurred in the use of these techniques for calibration of data of UK coastal waters have not previously been addressed. This paper describes a rigorous assessment of the errors incurred, allowing the limitations of the techniques to be established. This has resulted in recommendations for chlorophyll-a measurement in the coastal zone.

Le Tributyletain et Ses Produits de Degradation Dans L'Estuaire du Saint-Laurent (Canada) Tributyltin and Its Degradation Products in the St Lawrence Estuary (Canada)

The ubiquitous distribution of butyltins in Canadian coastal waters is now an important environmental concern and there is an urgent need for new set of data which could provide tools for an adequate environmental management. Surface sediments (first 5 cm) and mussels, collected in 1995 in four harbors and one control site located along the St Lawrence Estuary, were analyzed by gas chromatography/mass spectrometry (GC-MS) for their contain in tributyltin (TBT), dibutyltin (DBT) and monobutyltin (MBT). Results from the various sites are summarized as following: the harbor of Les Méchins was the most contaminated site with an average TBT concentration (dry weight) of 40 ±12 ng Sn g−1 in sediment and 145 ± 8 ng Sn g−1 in mussels collected near the dry dock, these values corresponding to a moderately contaminated environment; sediment and mussels from Gros-Cacouna and Rimouski-Est showed low contamination with concentrations in TBT below 28 ng Sn g−1 in sediment and below 72 ng Sn g−1 in mussels. However, contamination observed in the Rimouski-Est marina adjacent to the commercial harbor indicated a recent use of TBT-based antifouling paints; the Baie-Comeau area was only weakly contaminated in spite of an intense shipping traffic. Only DBT was detected at levels not exceeding 28 ng Sn g−1 in sediments and concentrations in mussels did not exceed 86 ng Sn g−1. The presence of low, but ubiquitous, concentrations of organotins in mussels (80% of samples) collected in the Bic provincial park, our control site, suggests a low contamination of the seawater mass circulating along the south shore of the St Lawrence Estuary by TBT during the summer. Results presented for mussels and surface sediments agree together and show that contamination levels were higher near harbor facilities and decreased rapidly outside of these harbors. For all sampled sites, mussels presented no danger for human consumption regarding their concentration in butyltins.

Le Tributyletain et Ses Produits de Degradation Dans L'Estuaire du Saint-Laurent (Canada) Tributyltin and Its Degradation Products in the St Lawrence Estuary (Canada)

The ubiquitous distribution of butyltins in Canadian coastal waters is now an important environmental concern and there is an urgent need for new set of data which could provide tools for an adequate environmental management. Surface sediments (first 5 cm) and mussels, collected in 1995 in four harbors and one control site located along the St Lawrence Estuary, were analyzed by gas chromatography/mass spectrometry (GC-MS) for their contain in tributyltin (TBT), dibutyltin (DBT) and monobutyltin (MBT). Results from the various sites are summarized as following: the harbor of Les Méchins was the most contaminated site with an average TBT concentration (dry weight) of 40 ±12 ng Sn g−1 in sediment and 145 ± 8 ng Sn g−1 in mussels collected near the dry dock, these values corresponding to a moderately contaminated environment; sediment and mussels from Gros-Cacouna and Rimouski-Est showed low contamination with concentrations in TBT below 28 ng Sn g−1 in sediment and below 72 ng Sn g−1 in mussels. However, contamination observed in the Rimouski-Est marina adjacent to the commercial harbor indicated a recent use of TBT-based antifouling paints; the Baie-Comeau area was only weakly contaminated in spite of an intense shipping traffic. Only DBT was detected at levels not exceeding 28 ng Sn g−1 in sediments and concentrations in mussels did not exceed 86 ng Sn g−1. The presence of low, but ubiquitous, concentrations of organotins in mussels (80% of samples) collected in the Bic provincial park, our control site, suggests a low contamination of the seawater mass circulating along the south shore of the St Lawrence Estuary by TBT during the summer. Results presented for mussels and surface sediments agree together and show that contamination levels were higher near harbor facilities and decreased rapidly outside of these harbors. For all sampled sites, mussels presented no danger for human consumption regarding their concentration in butyltins.

Magnitude of Stokes’ drift in coastal waters

The mechanism for Stokes’ drift is illustrated with the help of simple examples which apply either to surface or tidal waves, the mathematical steps for its calculation being worked out in detail for the general case of the travelling wave. Other types of motion such as standing waves or tides in rivers are then considered. Eventually orders of magnitude for the drift are deduced using data from Canadian coastal waters where current data are available. It turns out in general that Stokes' drift is of less than secondary importance, except for large amplitude surface waves or for swift currents in shallow water.

Storm surges in Canadian waters

Abstract Storm surges in various Canadian waters are reviewed. Following a brief discussion of the weather systems that cause storm surges in Canadian coastal and inland waters, the mathematical formulations to describe the development of storm surges are given. In reviewing storm surges in the different Canadian waters, particular attention is given to describe the influence of the presence of sea ice on surge development and the impact of shallow coastal areas, where the coastline configuration is itself changed by the surge, on inland penetration of the storm surge. The Canadian waters that may be affected by storm surges include the east and west coasts, the Beaufort Sea, the Gulf of St. Lawrence and the St. Lawrence estuary, Hudson Bay and the Great Lakes.

The distribution of dissolved vanadium in Eastern Canadian coastal waters

Dissolved vanadium measurements from the Gulf of St Lawrence and the Scotian shelf are reported. The Gulf of St Lawrence results reveal an average vanadium concentration of 24 nM in the deep water of the Gulf decreasing to 17·6 nM in the St Lawrence River. The Saguenay River had an even lower vanadium concentration of 5·1 nM. Linear increases in concentration with salinity were seen for both the St Lawrence estuary and the Saguenay fjord. In the Gulf of St Lawrence and on the Scotian shelf, depletion of vanadium in the surface waters and increasing concentrations with depth were observed. The vanadium-salinity relationships for these coastal waters both show increasing vanadium concentrations with increasing salinity and correlations that are indicative of extensive removal of dissolved vanadium from surface waters. On two offshore stations, the average vanadium concentration was 31 nM with no marked variation in concentration with depth. In general, the distributions can be explained in terms of the strengths of the input functions, be they rivers, atmospheric precipitation or oceanic advection, and the removal by biogenic scavenging processes.

AN ALGORITHM FOR ESTIMATING SURFACE SUSPENDED SEDIMENT CONCENTRATIONS WITH LANDSAT MSS DIGITAL DATA1

ABSTRACT: Algorithms for Landsat MSS digital data are needed to reduce the necessity of calibrating each Landsat scene if these data are to be useful in monitoring programs for surface suspended sediments. In this study digital data were extracted from 16 Landsat Multispectral Scanner (MSS) scenes collected between March 1987 and August 1988 over Enid Reservoir in North Central Mississippi. These data were converted to radiance and reflectance data for comparison with field measurements of surface suspended sediment concentrations. Concentrations ranged from 2 to 168 mg/1 during the study with only four greater than 100 mg/l. Linear and polynomial regression analyses were used to relate the surface suspended sediment concentrations with radiance and reflectance. Reflectance in MSS band 2 (0.6 to 0.7 μm) and MSS band 3 (0.7 to 0.8 μm) were best related to the surface suspended sediment concentrations with coefficients of determination accounting for 71 percent and 68 percent of the variation in the data, respectively. Regressions with radiance data accounted for 36 percent (band 2) or less of the variation. Logarithmic transformations of either reflectance or sediment concentrations increase the coefficients of determination for MSS band 2 reflectance data to 81 percent. Regressions between the ratio of MSS band 1 to MSS band 2 reflectances and concentrations also accounted for 80 percent of the variation. An equationLoge SS (mg/l) = 9.21R½+ 2.71R½2 + 8.45,where S is surface suspended sediment concentrations and R1/2 is the ratio of MSS band 1 to MSS band 2 reflectances, provided the best fit to the data with a coefficient of determination of 0.82. This equation is essentially the same as an algorithm proposed by Topliss et at. (1990), for estimating surface suspended sediment concentrations in Canadian coastal waters. These equations for Enid Reservoir and Canadian waters suggest that it may be possible to develop an algorithm for widespread use for estimating surface suspended sediments.

Baseline levels of heavy metals in the waters and sediments of Baffin Bay

Baseline levels of a number of trace metals have been determined in samples of water and sediment from Baffin Bay. Concentrations of Cr, Mn, Fe, Ni, Cu and Cd in the waters of Baffin Bay are generally lower than those observed in eastern Canadian coastal waters, levels being close to reported open ocean concentrations. Nearshore sediment samples, analysed for Cr, V, Mn, Ni, Co, Cu, Zn, Hg and Pb, display comparable concentrations to unpolluted muds in eastern Canadian coastal regions. Concentrations of these elements in the deep sediments of central Baffin Bay closely resemble levels in Atlantic Ocean deep-sea clays.

Manganese recycling in coastal waters

Abstract Both water and suspended particulate matter in the deep water of the Gulf of St. Lawrence are greatly enriched in manganese. Maximum dissolved manganese concentrations are encountered close to the sediment-water interface whereas the particulate matter with highest manganese content occurs 30–100 m above the bottom. The elevated concentrations are attributed to the diagenetic release of dissolved manganese from the underlying fine-grained sediments and its subsequent precipitation in the water column. The rate of manganese precipitation is rapid compared to the rates of diffusion and mixing in the bottom water. Part of the manganese-enriched particulate matter becomes mixed throughout the water column by advection and diffusion. Thus, particles enriched in manganese can ultimately be carried into the open ocean by prevailing currents. This process, which appears to be widespread in eastern Canadian coastal waters, enables manganese originally associated with rapidly settling terrigenous particles to be transferred to slowly settling fine-grained suspended particles entering the ocean from coastal environments. In this way, riverborne manganese of terrigenous origin may well account for a major proportion of the excess manganese in pelagic sediments.

A review of DREA's very low‐frequency ambient noise program

For the past 13 years, Defence Research Establishment Atlantic has been actively engaged in measuring properties of the low‐frequency ambient noise field in the North Atlantic Ocean and Canadian coastal waters. Concurrently, there has been a strong emphasis on developing surface‐suspended arrays that can reliably and inexpensively extend such measurements down to the infrasonic range. Special attention has been paid to hydrophone design and shrouding, and to minimizing the effects of sea‐surface motion and current shear. The success of this program has led to the construction of small superdirective research arrays, and more recently, quiet large‐aperture vertical and horizontal line arrays. Near‐surface noise directionality measurements made in midocean with these arrays complement reported results from bottom‐moored research arrays. The measurements of vertical directionality, in particular, show distinct trends, with arriving low‐frequency noise becoming more concentrated towards the horizontal in the northern ocean, and more diffuse with decreasing frequency. Azimuthal anisotropies are less pronounced, with some bias towards busy shipping lanes and fishing grounds.

Sensitivity of coastal waters to anthropogenic trace metal emissions

Trace metal concentrations in the waters of the Gulf of St. Lawrence and the Scotian Shelf and their sensitivity to changes in the composition of the major contributor of fresh water, the St. Lawrence River, are assessed. Comparison of the levels of trace metals in eastern Canadian coastal waters with those in other coastal waters of the world reveals that the former area generally has lower trace metal concentrations and is, therefore, probably less contaminated than elsewhere. The increased anthropogenic activity in the St. Lawrence drainage basin required to increase the levels of trace metals in receiving coastal waters by detectable amounts is discussed. We demonstrate that faster and more reliable warning of changes due to anthropogenic activity will be revealed through river monitoring than through monitoring of coastal waters. Changes in the marine environment can then be assessed through a thorough understanding of the geochemical behaviour of trace metals in nearshore waters.

The diet of harbor porpoises (Phocoena phocoena (L.)) in coastal waters of eastern Canada, with special reference to the Bay of Fundy.

Stomach contents of 81 harbor porpoises (Phocoena phocoena (L.)) collected from eastern Canadian coastal waters during 1969–1972 were examined. A total of 454 free otoliths and 54 undigested specimens representing a minimum of 281 fish, consisting of nine species in seven families, were recovered from the copious semidigested fish remains found in 52 of the stomachs. Clupea harengus (herring), Gadus morhua (cod), and Scomber scombrus (mackerel) otoliths accounted for more than 78% of the total. Osmerus mordax (smelt), Pollachius virens (pollock), Merluccius bilinearis (silver hake), Sebastes marinus (redfish), and Macrozoarces americanus (ocean pout) otoliths were also identified. Squid (Illex sp.), hagfish (Myxine glutinosa), and polychaetes (Nereis sp.) were identified in a few stomachs. Fifteen of the stomachs examined were empty or contained only fluid. Examination of the stomachs of the 16 smallest animals indicated that weaning occurred at body lengths of 100–104 cm.