Frontal zone analysis at the mouth of Saanich Inlet,British Columbia,Canada

The presence of a biological front at the mouth of an inlet (fjord) on the coast of British Columbia, Canada was established. The presence of the biological front was consistent with physical predictions based on water velocity and depth. The frontal zone was characterized by a high primary productivity and surface chlorophyll. From spectral analysis of data the zone was found to fluctuate under tidal influence so that observations made at a single point showed a 14-d cycle in chlorophyll maxima which was about 180° out of phase with maxima in tidal exchange.     

Microbial clumps in seawater in the euphotic zone of Saanich Inlet (British Columbia)

Viable heterotrophic microorganisms were enumerated to be 3.7±7.3 bacterial cells per microbial clump during summer in the euphotic zone of Saanich Inlet, British Columbia, Canada. Large microbial aggregates were observed, especially after the phytoplankton bloom, when the phytoplankton biomass formed about 1/2 the total suspended organic matter in the sea. The cell number per microbial clump was minimal when the phytoplankton fraction in the total suspended organic matter was almost 0 (i.e., before the phytoplankton bloom), and again when the phytoplankton bloom occurred. The size of the microbial clumps is discussed, particularly in reference to the food chain in the sea.The work was carried out at the Fisheries Research Board of Canada, Biological Station, Nanaimo, during the tenure of a National Research Council Post-doctoral fellowship.     

Sun-compass migration by Aurelia aurita (Scyphozoa): population retention and reproduction in Saanich Inlet,British Columbia

The scyphomedusa Aurelia aurita in Saanich Inlet, a north-south oriented fjord in British Columbia, uses a sun compass to migrate in a southeasterly direction during the day. When the sky is overcast and at night, A. aurita orients randomly and is dispersed passively by gentle tidal currents. The net result is daily reaggregation of medusae into enormous swarms along the southeastern shore of the fjord. Observations of spawning A. aurita in these swarms suggest that sun-compass migration and aggregative behavior may have evolved to facilitate reproduction and to maintain the population within this fjord throughout the year.     

Predatory behavior ofPhacellophora camtschatica and size-selective predation uponAurelia aurita (Scyphozoa: Cnidaria) in Saanich Inlet,British Columbia

Predation uponAurelia aurita byPhacellophora camtschatica was studied by SCUBA divers in a fjord in British Columbia between July and September 1986. The behavior and size ofP. camtschatica affected their foraging success. Larger predators captured more and larger prey. The size and behavior of the prey also affected the probability of capture. Predators were found at densities which can affect both the size composition and the overall numbers of the prey population.     

Population biology ofMacrocystis integrifolia from British Columbia,Canada

Aspects of the population dynamics ofMacrocystis integrifolia Bory were determined from harvested wild populations over a 26-month period and cultivated plants over a 40-month period. Mean wild plant size varied from 0.1 wet kg and two fronds in the winter to 3.1 wet kg and mine fronds in the summer. Plant recruitment probably occurred year-round with recruits making up 20 to 86% of the total population. Plant half-lives, estimated from population data, ranged from 1 to 3 months, with few plants exceedings 2 to 3 years in age. Standing crop ranged from 1.6 plants m^-2 and 0.1 wet kg m^-2 in winter to 8.3 plants m^-2 and 8 wet kg m^-2 in summer.     

Seasonal growth and productivity ofMacrocystis integrifolia in British Columbia,Canada

The seasonal growth rates and nitrogen and carbon fluxes were estimated for two subtidalMacrocystis integrifolia Bory kelp forests in British Columbia, Canada from changes in population structure through time. Mean relative growth rates of the forests varied from a high of 4.3% d^-1 to a low of-3.6% d^-1. Mean net assimilatioon rates of carbon (a photosynthesis analog) varied from a high of 0.66 g C m^-2 of foliage d^-1 to a low of-0.87 g C m^-2 d^-1. The leaf area index ranged from 0.3 to 11.9. Annual carbon input on a foliage area basis was calculated at 250 g C m^-2 yr^-1. Annual carbon input to the forest was estimated at 1 300 g C m^-2 of ocean bottom yr^-1. The yearly nitrate nitrogen input to the forest was estimated at 60 g N m^-2 of ocean bottom yr^-1. The net ecosystem production varied from-520 to +31 g C m^-2 of ocean bottom yr^-1. The intra-forest, inter-forest and seasonal variabilities of these productivity parameters are discussed.     

Modelling organic matter dynamics in headwater streams of south-western British Columbia,Canada

A mass-balance model was developed to simulate organic matter (OM) dynamics in headwater stream ecosystems of south-western British Columbia, Canada. Empirical data from two streams were used to structure and test a mass-balance model of the riparian–stream system. The model was driven by data on inputs, outputs, processing rates, discharge and water temperature. Statistical sub-models were derived for different processes (e.g. decomposition rates and periphyton growth). Inputs and outputs of OM were modelled on the basis of a series of assumptions of system properties, such as temperature and hydrological regimes. Major uncertainties identified through Monte-Carlo simulations of model predictions and variables important in controlling OM dynamics in these streams were dissolved OM (DOM) import and export, stream area and litterfall import. DOM was quantitatively the most important source of OM, accounting for 80% of total export of OM, followed by export of fine particulate organic matter (FPOM) at 15%. Different scenarios of logging and temperature regimes on the system were simulated to predict how these factors would affect standing stock of OM in the stream. When inputs of riparian litterfall were simulated to mirror reductions predicted from forest harvesting in the riparian area particulate OM (POM) standing stock was reduced by almost 80%. In comparison, a 3 °C increase in water temperature resulted in only a 20% reduction of POM standing stock due to enhanced mineralisation.     

Biodiversity and rockfish recruitment in sponge gardens and bioherms of southern British Columbia,Canada

In the Strait of Georgia and Howe Sound, British Columbia, colonies of individual cloud sponges, growing on rock (known as sponge gardens) receive resource subsidies from the high biodiversity of epifauna on adjacent rock habitats. Bioherms are reefs of glass sponges living on layers of dead sponges. In the same area as the sponge gardens, newly discovered bioherms in Howe Sound, BC (49.34.67 N, 123.16.26 W) at depths of 28- to 35-m are constructed exclusively by Aphrocallistes vastus, the cloud sponge. The sponge gardens had much higher taxon richness than the bioherms. The sponge garden had 106 species from 10 phyla, whereas the bioherm had only 15 species from 5 phyla. For recruiting juvenile rockfish (quillback, Sebastes maliger), the food subsidy of sponge gardens appears to be missing on bioherms of cloud sponge, where biodiversity is relatively low. While adult and subadult rockfishes (S. maliger, S. ruberrimus, S. proriger, and S. elongatus) were present on bioherms, no evidence for nursery recruitment of inshore rockfishes to bioherms was observed, whereas the sponge gardens supported high densities of newly recruited S. maliger, perhaps owing to the combination of both refuge and feeding opportunities. These results indicate that sponge gardens form a habitat for early stages of inshore S. maliger, whereas A. vastus bioherms are associated only with older juvenile and adult rockfishes.     

Correlations between forest fires in British Columbia, Canada, and sea surface temperature of the Pacific Ocean

Correlations and cross-correlations between forest fires in the province of British Columbia, Canada, and sea surface temperatures in the Pacific Ocean were evaluated. British Columbia has a long Pacific Ocean coastline; given that there may be teleconnections between the province's forest fires and climate variability over the ocean, significant correlations may exist between forest fires and the sea surface temperature of the Pacific Ocean. Fire occurrences and areas burned through lightning-caused and human-caused fires were analyzed against individual 1° × 1° grid cells of anomalies in the sea surface temperature to determine correlations for the period 1950-2006. Significant correlations (p < 0.05) for vast areas of the ocean were found between occurrences of lightning-caused fires and sea surface temperature anomalies for time lags of 1 and 2 years, whereas significant correlations between occurrences of human-caused fires and sea surface temperature anomalies occurred extensively for many time lags. To support the results of this approach, correlations between fire data and the Niño 3.4, Pacific Decadal Oscillation, and Arctic Oscillation indices were tested for the same period. Significant correlations were found between fire occurrences and these indices at certain time lags. Overall, fire occurrence appeared to be more extensively correlated with sea surface temperature anomalies than was area burned. These results support the hypothesis that teleconnections exist between fire activity in British Columbia and sea surface temperatures in the Pacific Ocean, and the correlations suggest that linear regression models or other regression techniques may be appropriate for predicting fire severity from the sea surface temperatures of one or more previous years.     

Heterotrophic bacterial dynamics in the lower Fraser River,its estuary and Georgia Strait,British Columbia,Canada

Annual cycles in the glucose heterotrophic potentials of the bacterioplankton of the lower Fraser River, its estuary and Georgia Strait surface waters were observed. Maximal microbial heterotrophic potentials were noted during the winter and early spring months, whereas maximal heterotrophic productivities were observed to occur during the summer and fall months. Temperature and soluble organic carbon levels appear to be the most important of the assayed physico-chemical parameters in regulating activities and productivities of the heterotrophic microbes of these waters.     

Susceptibility of non-indigenous ascidian species in British Columbia (Canada) to invertebrate predation

Non-indigenous ascidians are known to significantly alter the structure and composition of benthic communities and adversely affect shellfish aquaculture by fouling both the cultured species and the infrastructure. The ability of these species to persist in new locations and their current and potential distributions are dependent upon physiological tolerances to environmental factors and biotic resistance to competition and predation. Despite significant data on global invasion patterns, potential biotic resistance to non-indigenous ascidians is poorly understood. We identified potential predators of four non-indigenous ascidians (Styela clava, Botryllus schlosseri, Botrylloides violaceus, and Didemnum vexillum) in British Columbia (BC), Canada in order to: (1) assess the potential for biotic interference to limit the establishment and/or spread of these ascidian species in BC, and (2) identify candidate species to be used as ascidian biofouling control agents in shellfish aquaculture. Using a series of single- and multiple-choice laboratory experiments, potential benthic predators (including various species of molluscs, echinoderms, and arthropods) were offered non-indigenous ascidians as prey. The sea urchins Strongylocentrotus droebachiensis and Strongylocentrotus franciscanus, the sea stars Dermasterias imbricata and Evasterias troschelii, the nudibranch Hermissenda crassicornis, and the crabs Cancer productus and Carcinus maenas were found to consume one or more species of non-indigenous ascidians in single-choice experiments. However, when provided a choice, all predators chose their respective preferred food over ascidians. Thus, predation alone is unlikely to prevent large-scale establishment and spread of non-indigenous ascidians in BC, but it may have the potential to significantly reduce localized populations of ascidians. Green sea urchins, S. droebachiensis, were found to be efficient grazers of all four ascidian species, consuming 12.7 ± 5.14 cm² (mean ± SD) of adult B. violaceus over a 3-day period, 15 ± 3.7 juvenile colonies of B. violaceus over a 2-day period, and 63 ± 28.8 juvenile colonies of B. schlosseri over a 2-day period. Using sea urchins as biological control organisms may significantly reduce ascidian fouling in shellfish aquaculture.     

Evaluating the Effects of Three Forms of Marine Reserve on Northern Abalone Populations in British Columbia, Canada

Abstract: Marine reserves have been suggested as tools for assisting the management of fisheries by protecting vulnerable marine species from overexploitation. Although there is a theoretical basis for believing that marine reserves may serve as management tools, there are few marine reserves in the world in which to test their effectiveness. My research evaluated three forms of marine reserve on the south coast of Vancouver Island, British Columbia, Canada. I used northern abalone ( Haliotis kamtschatkana ), a severely depleted shellfish in this region, as an indicator of the effectiveness of the reserves. Abalone populations in eight sites receiving different degrees of spatial protection were counted and measured in situ during the spring of 1996 and 1997. In all sites with enforced harvest closures, populations of abalone were greater, and one site with nearly 40 years of protection had on average much larger (older) abalone. Reproductive output, as a function of abundance and size, was also greater in the enforced reserve areas. Larval dispersal from reserves, and hence the benefit to exploited areas, was not formally surveyed. Nevertheless, the results of my study, combined with knowledge of present abalone populations, life history, and regional hydrodynamics, suggest that establishment of reserves is justified in the absence of perfect knowledge of larval dispersal.     

Trend in the Status of Breeding Bird Fauna in British Columbia, Canada, Based on the IUCN Red List Index Method

Abstract:  The World Conservation Union (IUCN) Red List Index (RLI) is used to measure global trends in the status of biodiversity. We examined how the index might be used to measure the trend in the status of indigenous breeding birds in British Columbia between 1992 and 2006. We followed the RLI method described by Butchart et al. (2004, 2007) as closely as possible . Because IUCN Red List assessments at the regional level are not available in British Columbia, we used NatureServe S (subnational) ranking data. We calculated three index trend lines. The first two of these allowed us to compare an index based on our original data to one based on data that had been retrospectively corrected; the latter produced a smooth, flat line. A third trend line, based on the corrected data but excluding species new to province since 1947, produced a gently sloping downward trend. Ongoing immigration of bird species in and out of British Columbia added to the complexity of interpreting our regional RLI-type index, especially because our S-rank data did not incorporate transboundary "rescue" effects. Because the RLI is scaled so that the maximum value is based on a state in which all species are simultaneously ranked as least concern, it may exaggerate the highest potential status of intrinsically vulnerable species. A simpler, more intuitive graphic allows reporting that is less dependent on context. We believe the RLI approach holds useful innovation for an indicator of change in biodiversity within jurisdictional boundaries.     

The introduction of Littorina littorea to British Columbia, Canada: potential impacts and the importance of biotic resistance by native predators

Although the establishment and spread of non-indigenous species depends upon survival in the face of novel environmental conditions and novel biological interactions, relatively little attention has been focused on the specific role of native predators in limiting invasion success. The European common periwinkle, Littorina littorea, was recently introduced to the Pacific coast of Canada and provides a case study of an introduction into an area with an important predator guild (sea stars) that is functionally minor in the invader’s native habitat. Here, we assess the likelihood of establishment, spread, and negative ecological impact of this introduced gastropod, with an emphasis on the role of native sea stars as agents of biotic resistance. Size frequency distributions and local market availability suggest that L. littorea was most likely introduced via the live seafood trade. Non-native hitchhikers (e.g., the trematode Cryptocotyle lingua) were found on/in both market and field specimens. Laboratory studies and field observations confirmed that L. littorea can survive seasonal low salinity in Vancouver, British Columbia. Periwinkles also readily consumed native Ulva, suggesting that periwinkles could impact native communities via herbivory or resource competition. Unlike native gastropods, however, L. littorea lacked behavioural avoidance responses to Northeast Pacific predatory sea stars (Pisaster ochraceus and Pycnopodia helianthoides), and sea star predation rates on L. littorea were much higher than predation rates on native turban snails (Chlorostoma funebralis) in common garden experiments. We therefore expect periwinkle establishment in British Columbia to be limited to areas with low predator density, as is seen in its field distribution to date. We caution that this conclusion may understate the importance of the L. littorea introduction if it also serves as a vector for additional non-indigenous species such as C. lingua.     

Mosaicism of microplankton communities in the northern Strait of Georgia,British Columbia

The northern Strait of Georgia, British Columbia, Canada, was sampled five times between March and September 1986, employing a grid of stations spanning the strait. The spring diatom bloom was not observed and may have been suppressed by a combination of wind exposure and grazing by microzooplankton, notably non-loricate oligotrichs and the dinoflagellateGyrodinium spirale. Macrozooplankton were not studied. By June, the ecosystem was dominated by flagellates, and ciliate biomass was three times greater than that of the nanoflagellates. The photosynthetic dominantHeterosigma akashiwo was possibly inhibiting diatom growth, as environmental conditions were conducive to the latter's growth. During late summer (August–September), surface waters became nutrient-depleted and a mosaic of organismal types was formed. The pattern included diatoms on the more turbulent west side, nanoflagellates on the more stable east side, and dinoflagellates in the north associated with frontal boundaries. The driving force behind the mosaic appeared to be tidal turbulence and was most effective at times of advanced water-column stratification. Other points of interest were subsurface concentrations ofChaetoceros species, which were perhaps maintained at the pycnocline by entrainment in areas of high tidal turbulence, and a large ratio of heterotrophic to photoautotrophic biomass, possibly due to mixotrophy in ciliates.Please address all correspondence and requests for reprints to Dr. Taylor at the Department of Botany     

Anomalous arsenic concentrations in groundwaters of an island community, Bowen Island, British Columbia

Recently, occurrences of elevated arsenic concentrations in bedrock groundwaters used for individual and municipal water supplies have been recognised along the mainland coast of southern British Columbia, Canada. An area on Bowen Island (Queen Charlotte Heights community) was chosen to investigate the source(s) of arsenic, geochemical processes controlling its aqueous uptake, the role of geology and structure in the formation of these waters, and the use of hydrogeochemical survey methods for detecting arsenious groundwater regions. Pyrite- arsenopyrite-Cu mineralisation in the Queen Charlotte Heights area is present as veins associated with NE-trending fault zones and as disseminations in marginal breccia and stockwork zones of a ryhodacite porphyry stock. Near surface mineralisation was later altered by supergene events to form minor pyrite- arsenopyrite in a matrix of limonite and clay. Geochemical factors that control the concentration and mobility of arsenic in these groundwaters include: (a) anion exchange of arsenic from clay minerals during cation divalent/univalent exchange processes (water softening) which leads to waters of high pH and high anion exchange capacities; (b) desorption of arsenic from Fe and Al oxyhydroxide minerals during pronounced shifts in pH from acid to alkaline conditions brought on by the water softening process; and (c) stepwise oxidation of arsenopyrite mineralisation to form arsenious sulphate-bearing groundwaters. The inconsistent behaviour of the As3+ and As5+ ions during the complex waterrock interaction processes described above, precludes the use of detailed chemical analyses to predict relative abundances of the more toxic As3+ species. For a full appreciation of the toxic impact of groundwaters containing total arsenic concentrations that are above regulatory guidelines an arsenic speciation analysis is required.     

Co-existing populations of Pacific ocean perch, Sebastes alutus, in Queen Charlotte Sound, British Columbia

Variation at five microsatellite loci (Sal1, Sal2, Sal3, Sal4 and Sal5) was examined in approximately 1300 Pacific ocean perch (Sebastes alutus) sampled from 14 coastal sites in British Columbia, Canada. Mean observed heterozygosities by locus ranged from 71% to 88%, and by sample ranged from 75% to 84%. Theta values ranged from 0 to 0.04 over the five loci, and averaged 0.015. Among Pacific ocean perch samples, Š ranged from 0.001 to 0.056. Canonical discriminate analysis of multilocus genotypes and neighbour-joining analysis of pairwise genetic distances between samples both indicated the presence of three populations, one off the west coast of Vancouver Island (the Vancouver Island population) and two co-existing populations in Queen Charlotte Sound, Dixon Entrance and along the west coast of the Queen Charlotte Islands (the eastern and western QCI populations). Pacific ocean perch of the eastern and western QCI populations were caught in close proximity to each other, but individual samples showed little evidence of admixture. Fall and spring samples collected within geographic areas were genetically similar, indicating seasonally stable population structure. Restricted gene flow between the Vancouver Island and the two more northerly populations may result from limited adult dispersal and larval retention within the California Current and Alaska Gyre, respectively, but the presence of two populations within Queen Charlotte Sound cannot be explained entirely by larval retention hypotheses. The presence of two Pacific ocean perch populations in central British Columbia has implications for fisheries management.     

Genetic structure of rhinoceros auklets,Cerorhinca monocerata,breeding in British Columbia,Alaska, and Japan

Data from eight microsatellite markers screened in 246 rhinoceros auklets (Cerorhinca monocerata) from across the North Pacific revealed multiple genetic groups. The east (North America) to west (Japan) split was clearly evident in all analyses. Within the eastern Pacific, a minimum of three genetic groups are present. Surprisingly, rhinoceros auklets from Triangle Island, British Columbia, were genetically isolated from other nearby populations, including the breeding colony on Pine Island (~100 km to the east). A fourth genetic cluster (Chowiet Is) was detected using principal coordinate’s analysis; however, sample sizes were limited. Patterns of differentiation correspond to nonbreeding distributions with the eastern and western Pacific birds spending time off the west coast of North America and Japan, respectively, and may represent historical isolation in separate refugia during the Pleistocene glaciations. The patterns of genetic structure result from a combination of historical and contemporary factors influencing dispersal of rhinoceros auklets.     

Sensitivity of Systematic Reserve Selection to Decisions about Scale, Biological Data, and Targets: Case Study from Southern British Columbia

Abstract:  The identification of conservation areas based on systematic reserve-selection algorithms requires decisions related to both spatial and ecological scale. These decisions may affect the distribution and number of sites considered priorities for conservation within a region. We explored the sensitivity of systematic reserve selection by altering values of three essential variables. We used a 1:20,000–scale terrestrial ecosystem map and habitat suitability data for 29 threatened vertebrate species in the Okanagan region of British Columbia, Canada. To these data we applied a reserve-selection algorithm to select conservation sites while altering selection unit size and shape, features of biodiversity (i.e., vertebrate species), and area conservation targets for each biodiversity feature. The spatial similarity, or percentage overlap, of selected sets of conservation sites identified (1) with different selection units was ≤40%, (2) with different biodiversity features was 59%, and (3) with different conservation targets was ≥94%. Because any selected set of sites is only one of many possible sets, we also compared the conservation value (irreplaceability) of all sites in the region for each variation of the data. The correlations of irreplaceability were weak for different selection units (0.23 ≤ r ≤ 0.67), strong for different biodiversity features ( r = 0.84), and mixed for different conservation targets ( r = 0.16; 0.16; 1.00). Because of the low congruence of selected sites and weak correlations of irreplaceability for different selection units, recommendations from studies that have been applied at only one spatial scale must be considered cautiously.     

Industries and lung cancer: A population-based case-control study in British Columbia

An investigation was conducted to identify high-risk industries for histological subtypes of lung cancer based on a large population-based case-control study in British Columbia, Canada. Occupational histories and information on smoking and relevant covariates were collected from 14,755 male incident cancer cases. Industrial risk factors for 2998 lung cancer cases, including histological subtypes were assessed by logistic regression using other cancer cases, excluding smoking-related cancers, as controls. An excess risk of lung cancer was found among workers in mining, metal manufacturing, and electric power systems for all histological-subtypes, and construction, water transport, health services for specific histological subtypes. Industrial associations that are unique to histological subtypes of lung cancer were identified. Future research needs to focus on confirming these histological associations, and identifying the risk from key exposures found within these industries (e.g. medical radiation, electromagnetic fields, and cooking fumes).