Baynes Sound Research Articles

Development of a nature-based solution for mitigation of Pacific oyster summer mortality: use of the intertidal zone to improve resilience to environmental stressors

In recent years, Pacific oyster growers in British Columbia (BC), Canada have experienced devastating losses due to summer mortality syndrome. While anecdotal evidence suggests that intertidally-grown oysters may fare better during mass mortality events than deep-water counterparts, there remains a lack of research examining how different culture conditions may influence severity. To address this, we compared growth, condition, histopathology, reproductive status, and survival between intertidally- and deep-water-cultured oysters over 2 years at three oyster farms in Baynes Sound (BC). A reciprocal transplant was carried out after 1 year to test the use of the intertidal as a mechanism for promotion of physiological resilience prior to deep-water deployment. Field trial results showed significantly higher final survival in oysters transferred from the intertidal to deep water (83.5%) compared to those maintained in deep water (63.6%), but only at one farm, likely as a consequence of varying physical and/or biological characteristics associated with particular farm locations. Histopathology showed little role of disease with regards to varying survival among treatments, though higher occurrence of Viral Gametocytic Hypertrophy was observed in Year 1 oysters under deep-water (62.2%) versus intertidal (37.8%) conditions. Additionally, after 2 years, there was no significant difference in oyster size nor condition index between oysters transplanted from the intertidal to deep water and those solely cultured in deep water. A laboratory-challenge experiment determined significantly different survival curves of Year 1 intertidally- and deep-water-cultured oysters under immersion/emersion and warming conditions, with final survival of 88% and 64%, respectively, under conditions of high temperature (25°C) and immersion. Likewise, Year 2 (i.e. post-transfer) intertidally- and deep-water-cultured oysters showed significantly different survival curves under laboratory-based Vibrio challenge conditions (16°C) with final survival of 63% and 34%, respectively. Results suggest that partial culture in the intertidal at some farms may be an effective method for conferring resilience to summer mortality in Pacific oysters.

A Circulation Model for Baynes Sound, British Columbia, Canada

ABSTRACT An application of the three-dimensional Finite Volume Community Ocean Model was developed for Baynes Sound, British Columbia, Canada and a simulation was carried for the period of May 2016 to April 2017. The objective was to provide highly resolved spatial estimates of the regional hydrodynamics that could be used in a coupled biogeochemical model to assess the cultured shellfish carrying capacity of the region. The issue of how representative the particular simulation period was in the context of typical seasonal features was addressed by comparing temperatures, salinities and river discharges with long-term statistics. Circulation model results were generally in good agreement with salinity, temperature, velocity, and sea surface height observations, providing confidence in subsequent seasonal estimates of volume fluxes through the two entrances and water-renewal. Approximately sixty percent of the variability in near-surface temperature observations at five locations was shown to be linearly dependent on a combination of the along-sound wind, air temperature, and the daily sea surface range, which was taken as a proxy for tidal mixing.

Role of the Vibrio community, reproductive effort, and environmental parameters in intertidal Pacific oyster summer mortality in British Columbia, Canada

In recent years, mortality of cultured Pacific oysters (Crassostrea gigas) during July and August has regularly exceeded 50% in many oyster farms in Baynes Sound, British Columbia (BC), Canada. However, little is known about the bacterial diversity and environmental/biological conditions that may be contributing to such mortality events in the region. A study of Pacific oysters in intertidal culture trays was conducted during the summer of 2017 in Baynes Sound to monitor the occurrence of oyster mortality, while identifying potentially pathogenic bacteria present in the oysters, examining oyster reproductive development, and recording various environmental parameters (temperature, salinity, dissolved oxygen, chlorophyll a, carbon chemistry, phytoplankton species/abundance, zooplankton species/abundance) at three farm sites in Buckley Bay, Fanny Bay, and Ship's Point. Continuous mortality was observed throughout July and August, cumulative mortalities ranging from 16.5 to 35.1% at the three sites. Mortality over time was examined with a binomial generalized linear mixed-effects regression model, which demonstrated a correlation with date, tides, temperature, gonad somatic index, and gonad developmental phase (Rc2 = 0.598). Average cumulative mortality per module was highly correlated with average oyster gonad length and the proportion of female oysters in a multiple linear-regression model (p = 0.002, R2 = 0.824). A total of 158 bacterial isolates were cultured and identified based on sequencing of the recA gene. Among those isolates, Vibrio aestuarianus and V. harveyi, with 27 and three isolates, respectively, are well-documented pathogens of Pacific oysters in other regions. This study is the first to concurrently evaluate a broad array of factors potentially associated with Pacific oyster summer mortality in BC. We provide evidence that summer mortality of Pacific oysters in Baynes Sound is occurring with an etiology similar to summer mortalities of adult Pacific oysters reported in other countries.

Hydrodynamic Controls on the Particle Size of Resuspended Sediment from Sandy and Muddy Substrates in British Columbia, Canada

Kassem, H.; Sutherland, T.F., and Amos, C.L., 2021. Hydrodynamic controls on the particle size of resuspended sediment from sandy and muddy substrates in British Columbia, Canada. Journal of Coastal Research, 37(4), 691–707. Coconut Creek (Florida), ISSN 0749-0208.A benthic annular flume, Sea Carousel, was deployed at both sand-dominated (Baynes Sound) and mud-dominated (Carrie Bay) stations in British Columbia, Canada, to examine the character of near-bed flow over these contrasting bottom types and its control on particle size of resuspended sediment. An assessment has also been made of the turbidity-induced drag reduction due to suspension of bottom sediments. The median sizes of suspended material from the sandy sites have been compared with the well-known Rouse theory, whereas the aggregates resuspended from muddy stations were scaled with the energy dissipation rate (e) determined from high-frequency three-dimensional flow measures in the flume. There was no evidence in the turbulence spectra in the Sea Carousel of energy inputs in the paddle and lid rotational frequencies, and a f–5/3 slope for f > 2 Hz in turbulent transitional flows was evident. The bed roughness length of sandy sites was Reynolds-number dependent but was asymptotic to a constant value of 2 mm at high flows. This equated to a dimensionless drag coefficient at 1 m above bed of a constant, 3 × 10–3 (also at high Reynolds numbers), which agrees well with values reported in the literature. The median size of suspended sand (from the sandy sites) and equivalent still water settling rate (ws) scaled with the friction velocity (u*) in the form ws/u* = D*/8. The median size of resuspended aggregates (df) scaled inversely with dissipation (e) in the form df = 5 × 10–6e–0.24m, which is close to the relationship found in the literature.

Assessing size-based exposure to microplastic particles and ingestion pathways in zooplankton and herring in a coastal pelagic ecosystem of British Columbia, Canada

Microplastic particles (hereafter 'microplastics') are a widespread class of pollutants in marine environments that can become embedded in food webs. Due to their diverse composition and size, microplastics can enter food webs both directly through consumption and indirectly via trophic transfer. In this study, we investigated potential ingestion pathways of microplastics in an important pelagic food web in coastal British Columbia, Canada. Between March and September 2019, we completed repeat surveys of water, zooplankton, and larval Pacific herring Clupea pallasii at 11 locations in Baynes Sound, Strait of Georgia. Five zooplankton taxa were isolated from each zooplankton sample for specific analysis. Juvenile herring were sampled once in September. Samples were cold-digested with KOH or H2O2 and suspected microplastics isolated. Suspected microplastics were confirmed using μ-Raman spectroscopy and were subsequently identified from the collected samples. The average microplastic concentration in surface waters was 0.59 microplastic particles l-1, and no clear spatial pattern was evident. Average microplastic particle loads were 0.0007 ind.-1 in zooplankton, 0.0017 ind.-1 in larval herring, and 0.089 ind.-1 in juvenile herring. There was a clear difference in the biological:microplastic particle ratio across size fractions (125-250, 250-500, 500-1000, 1000-2000, 2000-4000 µm) in the water column. In size classes <1000 µm, biological particles outnumbered microplastic particles by up to 4 orders of magnitude, whereas for size classes >1000 µm, the ratio decreased to nearly 1. Zooplanktivorous consumers like juvenile herring are more likely to consume microplastics than prey since the ratio of microplastic particles >1000 µm to potential food, and therefore encounter rate, is higher.

Use of sediment dwelling bivalves to biomonitor plastic particle pollution in intertidal regions; A review and study.

We explore the possibility of using the varnish (Nutallia obscurata) and Manila (Venerupis philippinarum) clams as biomonitors of microplastics (MPs) pollution. A short review is first provided on the use of bivalves for biomonitoring MPs in aquatic ecosystems. From the conclusions drawn from our review we determine if the sediment dwelling varnish and Manila clam could possibly be good choices for this purpose. We sampled 8 intertidal sites located within two distinct regions of coastal British Columbia, Burrard Inlet (5 sites) and Baynes Sound (3 sites). Each intertidal region had its own particular use; within Burrard Inlet, BMP a heavily used marine park, CP, EB, J, and AP, popular local beaches, and within Baynes Sound, Met and NHB, two intertidal regions heavily exploited by the shellfish industry and RU an intertidal region with limited aquaculture activity. Microfragments were recovered from bivalves collected from all intertidal regions except for AP. Microspheres were recovered primarily from bivalves sampled from Baynes Sound at NHB where high numbers of spheres within sediments had previously been reported. BMP and Met had the highest number of particles present within individual clams which were predominantly high density polyethylene (HDPE) and a polypropylene composite (PPC). Both polymers are extensively used by the shellfish industry in all gear types, as well as in industrial and recreational marine activities. The spatial distribution of recovered MPs was indicative of the anthropogenic use of the intertidal region suggesting these bivalves, for microfragments and microspheres, may be suitable as biomonitors and could prove to be useful tools for determining whether reduction policies for plastics use are having a positive effect on their release into marine environments.

An In Situ Assessment of Seabed Stability in Baynes Sound, British Columbia, Canada

Sutherland, T.F. and Amos, C.L., 2020. An in situ assessment of seabed stability in Baynes Sound, British Columbia, Canada. Journal of Coastal Research, 36(3), 472–486. Coconut Creek (Florida), ISSN 0749-0208.The Sea Carousel, an annular flume, was deployed to examine (in situ) fundamental parameters of seabed stability in Baynes Sound, British Columbia, Canada. Sediment grain size, water and organic contents, and chlorophyll and phaeopigment concentrations were collected to establish a hierarchy of factors associated with seabed stability. Sediment stability increased toward the Sound entrance in concert with decreases in water, organic, and silt–clay contents and a transition from cohesive to noncohesive properties. Bed-stress estimates, based on the quadratic stress law and turbulent kinetic energy (TKE) methods, showed a decrease in the drag coefficient from the inner (0.04) to the outer (0.0015) Sound. Surface erosion thresholds ranged between 0.04 to 0.28 Pa, whereas the friction coefficients (e.g., the failure envelop) were on average 12°, representing normally consolidated sediments. Type I (floc) erosion occurred at low shear stresses, whereas type II (mass) erosion happened at higher values. Erosion rates (E, for type I erosion) fitted a power function of excess shear stress (Em = τ0 – τcrit,z)m with zero offset, where 0.81 < m < 2.32. The lowest and highest values for a given excess-shear stress occurred in the inner Sound and outer Sound, respectively. Settling of (resuspended) sediment after an exponential decay law [d(SSC)/dt] = SSC0 (exp–kt), where k fell within that of published values (3 < k < 539). Higher values of k (fastest settling) were observed in the inner Sound relative to the outer Sound. The sedimentation diameter (ds) fell in a coarse–silt to fine-sand range and was larger in the outer Sound, reflecting a coarsening of bed sediments.

Commentary on: Abundance and distribution of microplastics within surface sediments of a key shellfish growing region of Canada.

This formal comment is in response to “Abundance and distribution of microplastics within surface sediments of a key shellfish growing region of Canada” written by Kazmiruk and colleagues in 2018. This article presents microplastics concentrations in sediment, primarily microbeads, within Baynes Sound, British Columbia, which are some of the highest that have been reported anywhere in the world. The authors cite the local shellfish industry as the likely source of this high degree of contamination and present the industry as a substantial risk to the environment. However, the authors do not sufficiently justify the efficacy of their methodology, and there are several flaws which call into question the legitimacy of their findings. In this commentary, we address the microplastic abundances reported by the authors, and methodological concerns. Furthermore, we provide additional data to elucidate some of this study’s more contentious findings. Specifically, we seek to clarify the visual identification of microbeads and microfibres, and the microplastic concentration within shellfish populations, water, and sediment, within the Baynes Sound shellfish growing region.

Size and shape matter: A preliminary analysis of microplastic sampling technique in seawater studies with implications for ecological risk assessment

Microplastic particles (MPs) are widely distributed in seawater. Fibrous MPs (microfibres) are often reported as the most commonly encountered shape of particle. To estimate MP concentrations in seawater, samples are often collected using towed nets (generally 300–350-μm mesh) and may underestimate the amount of microfibres present, which may pass through the mesh due to their narrow width. We compared the potential microplastic particle (PMP) concentration estimates provided by two different seawater sampling methods conducted at three commercial shellfish farms and three unfarmed sites in Baynes Sound, British Columbia, Canada. The methods were: 10-L bucket samples sieved through 63-μm mesh in situ and subsequently filtered through an 8-μm polycarbonate membrane; and 1-L bulk samples collected in jars and subsequently filtered to 8 μm. The jar samples yielded PMP concentrations averaging approximately 8.5 times higher than the bucket samples per L of water (at the site level), largely driven by differences in the number of microfibres. There was no significant difference in PNP concentration between shellfish farms and unfarmed sites. An analysis of MP concentrations and mesh sizes reported in the literature suggests that using a 300–350-μm mesh may underestimate total MP concentrations by one to four orders of magnitude compared with samples that are filtered through much smaller mesh sizes (e.g. <100 μm), despite the effect of sample volume. Particles <300 μm in diameter make up a large component of MPs commonly found in fish and invertebrates. As such, common sampling practices fail to adequately measure a biologically relevant class of MPs, thereby undermining the ability to quantify ecological risk. We suggest that seawater sampling methods be designed to filter to <10 μm (the approximate width of many microfibres), either using pressurized pumps for large-volume samples, or by using sufficient replication of small-volume discrete samples.

Seabed Attributes and Meiofaunal Abundance Associated with a Hydrodynamic Gradient in Baynes Sound, British Columbia, Canada

ABSTRACT Sutherland, T.F.; Garcia-Hoyos, L.M.; Poon, P.; Krassovski, M.V.; Foreman, M.G.G.; Martin, A.J., and Amos, C.L., 2018. Seabed attributes and meiofaunal abundance associated with a hydrodynamic gradient in Baynes Sound, British Columbia, Canada. The distribution of seabed geotechnical, biochemical, and meiofauna attributes was examined in Baynes Sound, British Columbia, between 2009 and 2014. Among attributes measured were sediment porosity, organic carbon and nitrogen, and trace element concentrations (e.g., zinc, copper), which increased with increasing sediment fines content toward the head of the Sound. A ternary plot (sand-silt-clay percentages) revealed a constant clay/silt ratio across a range of sand proportions with textures ranging from well-sorted sand at the high-energy SE entrance to silt-dominated mud in the depositional basin. These sediment textures were related to modeled maximum velocity values within 5 m of the seabed (Umax,5), with highest values (restricted entrance) and lowes...

Beach-cast deposition and commercial harvesting of a non-indigenous alga, Mazzaella japonica: Implications for macrofauna communities in Baynes Sound, British Columbia

Accumulations of beach-cast seaweeds and other debris, collectively known as wrack, are a common and ecologically important occurrence along coastal regions worldwide. As the rate of seaweed introductions continues to increase, so too does their beach-cast collection for aesthetic or commercial purposes. The ecological effects of these harvests are poorly characterized in the literature, especially for nutrient-rich regions such as the Northeast Pacific. Within the southern extremity of Baynes Sound, British Columbia, beach wrack contains an introduced species of red alga called Mazzaella japonica, which became the target of a commercial beach-cast harvest in 2007. The objectives of this research were threefold: 1) to quantify the contribution of M. japonica to wrack inputs within the harvest region; 2) to explore how wrack characteristics influence macrofauna communities; and 3) to determine if the commercial removal of beach-cast seaweeds has a detectable effect on wrack characteristics and macrofauna communities. To answer these questions we monitored a series of permanent transects at six sites across the harvest region from November 2014 until March 2015. We recorded as much as 853 kg (±173 SD) of wrack per meter of shoreline, approximately 90% of which was M. japonica. Despite the removal of 675 tonnes of beach-cast seaweeds, we found that the trends in wrack biomass were similar between both harvested and unharvested locations. Macrofauna communities differed between study sites, as well as with the age class, and depth of the wrack from which they were sampled. These findings contribute to the limited literature on beach-cast seaweed harvesting and provide an important record of M. japonica wrack inputs for future research or monitoring of this non-indigenous seaweed.

Abundance and distribution of microplastics within surface sediments of a key shellfish growing region of Canada.

The abundance and distribution of microplastics within 5 sediment size classes (>5000 μm, 1000–5000 μm, 250–1000 μm, 250–0.63 μm and < 0.63 μm) were determined for 16 sites within Lambert Channel and Baynes Sound, British Columbia, Canada. This region is Canada’s premier growing area for the Pacific oyster (Crassostrea gigas). Microplastics were found at all sampling locations indicating widespread contamination of this region with these particles. Three types of microplastics were recovered: microbeads, which occurred in the greatest number (up to 25000/kg dry sediment) and microfibers and microfragments, which were much less in number compared with microbeads and occurred in similar amounts (100–300/kg dry sediment). Microbeads were recovered primarily in the < 0.63 μm and 250–0.63 μm sediment size class, whereas microfragments and microfibers were generally identified in all 5 sediment size classes. Abundance and distribution of the three types of microplastics were spatially dependent with principal component analysis (PCA) indicating that 84 percent of the variation in abundance and distribution was due to the presence of high numbers of microbeads at three locations within the study region. At these sites, microbeads expressed as a percent component of the sediment by weight was similar to key geochemical components that govern trace metal behavior and availability to benthic organisms. Microbeads have been shown to accumulate metals from the aquatic environment, hence in addition to the traditional geochemical components such as silt and organic matter, microplastics also need to be considered as a sediment component that can influence trace metal geochemistry. Our findings have shown that BC’s premier oyster growing region is highly contaminated with microplastics, notably microbeads. It would be prudent to assess the degree to which oysters from this region are ingesting microplastics. If so, it would have direct implications for Canada’s oyster farming industry with respect to the health of the oyster and the quality of product that is being farmed and sets an example for other shellfish growing regions of the world.

Disease and mortality among Yesso scallops Patinopecten yessoensis putatively caused by infection with Francisella halioticida.

During the fall of 2015, up to 40% mortality occurred in juvenile Yesso scallops Patinopecten yessoensis at an aquaculture site in Baynes Sound, British Columbia, Canada. Macroscopic lesions were present in 11% of the scallops, and histopathology consisting of multifocal and diffuse haemocyte infiltration was observed in 44% of the specimens examined. Histologically, small Gram-negative intracellular bacteria-like particles were observed within necrotic haemocytes of the lesions, suggesting a bacterial aetiology. DNA was extracted from adductor muscle lesions of diseased scallops, and the 16s rDNA gene as well as the DNA-directed RNA polymerase beta subunit (rpoB) were amplified by PCR. Sequence analyses of the resulting 413 and 925 bp fragments were a 100% match to the reference sequence for Francisella halioticida, originally described as the cause of mortality in abalone from Japan. Isolation and culture of the bacteria was not possible at the time, as no further diseased specimens were available. Results from in situ hybridization assays as well as examination by transmission electron microscopy provide further evidence supporting the hypothesis that F. halioticida was the most probable causative agent of the lesions and mortality.

Habitat effects on early post-settlement growth of intertidal clams,Venerupis philippinarum(A. Adams &amp; Reeve, 1850)

Understanding early growth is important for linking population dynamics with the ecological role played by bivalves in marine systems. Extensive literature exists for growth rates of juvenile and adults (>1 mm), but much less is known about growth rates during the period immediately following settlement in natural settings. In this study, growth rates from six cohorts of recently settled and metamorphosed (<300 µm) Manila clams (Venerupis philippinarum) are reported. Early post-settlement growth is compared over 2 years and from four intertidal sites in Baynes Sound, British Columbia, Canada, to assess how growth varies in response to local habitat (sediment chemistry and grain size) and conspecific abundance (Allee effects). Growth rates ranged from 2.8 to 5.3 µm d−1; instantaneous growth ranged from 0.005 to 0.007 d−1. Early post-settlement growth showed no density dependence relative to conspecific early recruit density or adult biomass. Average daily growth of early post-settlement clams was negatively correlated with inorganic carbon, organic carbon and nitrogen in the sediment, and growth tended to increase with increasing fraction of gravel. Early post-settlement growth rates observed here are less than those reported elsewhere for V. philippinarum, a discrepancy that may be explained by latitudinal differences and/or differences in settlement timing.

Microplastic Ingestion by Wild and Cultured Manila Clams (Venerupis philippinarum) from Baynes Sound, British Columbia.

Microplastics, plastic particles <5mm, are an emerging concern in aquatic ecosystems. Because microplastics are small, they are available to many filter-feeding organisms, which can then be consumed by higher trophic level organisms, including humans. This study documents the quantity of microplastics present in wild and cultured Manila clams (Venerupis philippinarum). Three active shellfish farms and three reference beaches (i.e., non-shellfish farm sites) in Baynes Sound, British Columbia were chosen to examine the microplastic concentrations in wild and cultured Manila clams. Microplastics were isolated using a nitric acid digestion technique and enumerated from 54 clams (27 farmed and 27 non-farmed). Qualitative attributes, such as colour and microplastic type (fiber, fragment, or film) also were recorded. There was no significant difference (F=1.29; df=1,4; P=0.289) between microplastic concentrations in cultured and wild clams. Microplastic concentrations ranged from 0.07 to 5.47 particles/g (from reference beach and shellfish farm clams, respectively). Fibers were the dominant microplastic (90%); colourless and dark gray fibers were the most common colours observed (36 and 26%, respectively). Although this indicates that microplastics are definitely present in seafood consumed by humans, shellfish aquaculture operations do not appear to be increasing microplastic concentrations in farmed clams in this region.

Seeing shellfish from the seashore: The importance of values and place in perceptions of aquaculture and marine social–ecological system interactions

In increasingly crowded and contested marine and coastal spaces, there is a pressing need to identify the values, context, culture and other factors that shape what activities will be resisted, tolerated, or desired in those spaces. The concept of wellbeing provides a useful analytical lens to address this need. This study characterizes the impact of shellfish aquaculture on local residents in Baynes Sound, British Columbia across environmental, economic and experiential dimensions by creating an overall index of attitudes towards the industry. Findings suggest that perceptions of impacts within the environmental and experiential dimensions are connected, while the economic dimension is somewhat distinct. Attitudes towards the industry were also widely variable within the sample, and the most important predictor variables of attitudes are not those related to common narratives about groups who ‘like’ or ‘dislike’ the industry. Rather, these variables are related to general environmental beliefs and place (local community of residence). These findings have important management implications as they demonstrate that local contextual (cultural and other) boundaries have critical influences on any assessment of well-being, how it is defined, and its relationship to marine coastal zone activities like aquaculture.

Intertidal Concentrations of Microplastics and Their Influence on Ammonium Cycling as Related to the Shellfish Industry.

Microplastics are ubiquitous within the marine environment. The last 10 years have seen research directed at understanding the fate and effect of microplastics within the marine environment; however, no studies have yet addressed how concentrations of these particles could affect sedimentary processes such as nutrient cycling. Herein we first determine the concentration and spatial distribution of microplastics within Baynes Sound, a key shellfish-growing area within coastal British Columbia (BC). We also determined sediment grain size and % organic matter (OM) such that we could relate spatial patterns in sediment microplastic concentrations to sedimentary processes that determine zones of accretion and erosion. Using field-determined concentrations of microplastics, we applied laboratory microcosms studies, which manipulated sediment concentrations of microplastics, OM, and bivalves to determine the influence of sediment microplastics on ammonium cycling within intertidal sediments. Concentrations of microplastics determined within the intertidal sediment varied spatially and were similar to those found in other coastal regions of high urban use. Concentrations were independent of grain size and OM suggesting that physical processes other than those that govern natural sediment components determine the fate of microplastics within sediments. Under laboratory conditions, concentrations of ammonium were significantly greater in the overlying water of treatments with microplastics, clams, and OM compared with treatments without microplastics. These preliminary studies suggest that high concentrations of microplastics have the potential to alter key sedimentary processes such as ammonium flux. This could have serious implications, for example, contributing to eutrophication events in regions of the coast that are highly urbanized.

Community composition of the intertidal in relation to the shellfish aquaculture industry in coastal British Columbia, Canada

The intertidal region of the Pacific Northwest is under ever increasing pressure to be used exclusively for the industrial sized operations of shellfish aquaculture. In British Columbia (BC), aquaculture practices include seeding the intertidal with the non-indigenous Venerupis philippinarum followed by the application of anti-predator netting. Ecological consequences of such practices applied at large scales are unknown. To assess for possible impacts 28 farm and reference sites from 3 geographically distinct regions of BC were surveyed in each of two years and their epibenthic, endobenthic and macroflora communities compared. The three regions differed in their intensity of industry from low (Barkley), medium (Desolation) to high (Baynes). Marked regional differences in intertidal community composition were observed. Of the three regions Baynes Sound, which has 101 tenures, was the most altered with the greatest numbers of the invasive species, Batillaria sp. and Hemigrapsus oregonensis. Barkley Sound, the region with the lowest industrial intensity, was characterized by Mytilus trossulus and the absence of H. oregonensis. The mid-intensity region, Desolation Sound, was characterized by Littorina scutulata and Tectura persona. Within Baynes Sound, seeding appears to be acting as an attractant for crab predators with farm sites having on average 3-fold greater numbers as compared to reference sites. Farming practices were also found to encourage growth and biofouling of the intertidal with Ulva sp. Consequences of changes in community composition in this case, an increase in the abundance of a major intertidal predator, H. oregonensis, on ecosystem functioning within these sensitive coastal areas are not known.

Properties of Blood, Porphyrins, and Exposure to Legacy and Emerging Persistent Organic Pollutants in Surf Scoters (Melanitta perspicillata) Overwintering on the South Coast of British Columbia, Canada

The surf scoter (Melanitta perspicillata) is a little-studied species of North American sea duck. Estimates suggest it has experienced a precipitous decline in breeding numbers over the latter half of the past century. To investigate the potential role of contaminant uptake and toxicity in the population decline, this study undertook to measure blood chemistry, porphyrin concentrations, EROD, and organic contaminants in mature surf scoters wintering in the Strait of Georgia, BC, Canada. Hepatic organochlorine pesticide, polychlorinated dibenzo-p-dioxin, polychlorinated dibenzofuran, polychlorinated biphenyl (PCB), polybrominated diphenyl ether, and nonylphenol concentrations were relatively low; for example, ΣTEQs (toxic equivalents) for PCBs, dioxins, and furans combined ranged from 4.7 ng/kg wet weight in reference-site (Baynes Sound) birds to 11.4 ng/kg wet weight in birds from Vancouver Harbour. Nonetheless, elevated EROD activity indicated that birds in Howe Sound were responding to an Ah-receptor-mediated stressor, which was also affecting hematocrit values and possibly vitamin A status. In addition, a low proportion of lymphocytes in individuals across locations in early spring samples was associated with poor body condition. The apparent loss of fitness just prior to the onset of northerly migrations to breeding grounds is of particular concern. Compromised health of mature birds at this point in the season might impact negatively on the productivity and survival of some individuals, particularly those overwintering in Howe Sound.

Movements of Pre-migratory Surf and White-winged Scoters in Response to Pacific Herring Spawn

Abstract We documented the movement and distribution patterns of wintering Surf Scoters (Melanitta perspicillata) and White-winged Scoters (Melanitta fusca) in relation to herring spawn events in the Strait of Georgia, British Columbia. Radio-telemetry and surveys were conducted in Baynes Sound, an important wintering area where scoters feed primarily on clams. In early March, herring spawn events in areas adjacent to Baynes Sound provide a short-term pulse of abundant and easily accessible food, which could affect habitat use by wintering scoters from Baynes Sound. Radio-marked Surf Scoters and White-winged Scoters exhibited limited movements during winter, in contrast to the spring herring spawn season, when both scoter species moved greater distances to access herring eggs. Most individuals were located near spawning locations at least once during the spawning season, and the majority of telemetry locations were close to spawning sites, with Surf Scoters showing a higher association with spawn for both...