Abundance and distribution of beach litter with acutely toxic metal concentrations.

We determined if colour, category (e.g., food packaging) or intertidal activity could explain the occurrence of litter with acute levels of metals. Six beaches were sampled; an industrial site, a local and remote park and three beaches. Food packaging accounted for 66% of litter with acute levels of metals found in 10% of samples. Acute levels were independent of colour and category, but dependent on intertidal region and its anthropogenic use. Litter with acute levels of cadmium and lead were recovered from the industrial intertidal and high concentrations of zinc and cadmium associated with candy wrappers were found on recreational beaches. In addition to the intrinsic and extrinsic loads that litter carries, also too are memory effects, i.e., the previous use of the item carries over its trace metal burden posing extreme risks to marine ecosystems. In the managing of risk associated with beach litter, legacy contaminants need be considered.

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.

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.

Macro and micro plastics sorb and desorb metals and act as a point source of trace metals to coastal ecosystems.

Nine urban intertidal regions in Burrard Inlet, Vancouver, British Columbia, Canada, were sampled for plastic debris. Debris included macro and micro plastics and originated from a wide diversity of uses ranging from personal hygiene to solar cells. Debris was characterized for its polymer through standard physiochemical characteristics, then subject to a weak acid extraction to remove the metals, zinc, copper, cadmium and lead from the polymer. Recently manufactured low density polyethylene (LDPE), nylon, polyethylene terephthalate (PET), polypropylene (PP), polystyrene (PS) and polyvinyl chloride (PVC) were subject to the same extraction. Data was statistically analyzed by appropriate parametric and non-parametric tests when needed with significance set at P < 0.05. Polymers identified in field samples in order of abundance were; PVC (39), LDPE (28), PS (18), polyethylene (PE, 9), PP (8), nylon (8), high density polyethylene (HDPE, 7), polycarbonate (PC, 6), PET (6), polyurethane (PUR, 3) and polyoxymethylene (POM, 2). PVC and LDPE accounted for 46% of all samples. Field samples of PVC, HDPE and LDPE had significantly greater amounts of acid extracted copper and HDPE, LDPE and PUR significantly greater amounts of acid extracted zinc. PVC and LDPE had significantly greater amounts of acid extracted cadmium and PVC tended to have greater levels of acid extracted lead, significantly so for HDPE. Five of the collected items demonstrated extreme levels of acid extracted metal; greatest concentrations were 188, 6667, 698,000 and 930 µgg-1 of copper, zinc, lead and cadmium respectively recovered from an unidentified object comprised of PVC. Comparison of recently manufactured versus field samples indicated that recently manufactured samples had significantly greater amounts of acid extracted cadmium and zinc and field samples significantly greater amounts of acid extracted copper and lead which was primarily attributed to metal extracted from field samples of PVC. Plastic debris will affect metals within coastal ecosystems by; 1) providing a sorption site (copper and lead), notably for PVC 2) desorption from the plastic i.e., the "inherent" load (cadmium and zinc) and 3) serving as a point source of acute trace metal exposure to coastal ecosystems. All three mechanisms will put coastal ecosystems at risk to the toxic effects of these metals.

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.

Favored use of anti-predator netting (APN) applied for the farming of clams leads to little benefits to industry while increasing nearshore impacts and plastics pollution.

An overview of the efficacy of anti-predator netting (APN) used by the shellfish industry is presented. There is little support that the currently favored APN effectively protects farmed clams from predators. Evidence does suggest that APN leads to impacts and pollution. APN is an attractant for predators, e.g., crabs, by providing a refuge within Ulva sp. which attaches onto the surface of APN. APN entrains silt and organic matter and increases sediment temperatures degrading habitat underneath the APN. APN present hazards to fish and wildlife and is a source of plastics to the marine environment. The continued use of ineffective APN does not serve either the environment or industry well, and many of these issues could be addressed through the alternate use of "ancient" technology used by aboriginal people to maintain clam gardens; building of rock walls optimizing the amount of clam habitat thereby increasing numbers without the use of APN.

Trace elements in Pacific Dunlin (Calidris alpina pacifica): patterns of accumulation and concentrations in kidneys and feathers.

Trace element concentrations were measured in Pacific Dunlin (Calidris alpina pacifica) to identify factors that influence accumulation and to assess toxicity risks. We report concentrations of cadmium, copper, and zinc in kidneys as well as copper, lead, mercury, selenium and zinc in feathers. Relationships between element concentrations and Dunlin age, sex, bill length, habitat preference, trophic level, and sample group were investigated with regression analyses. Stable isotope ratios of carbon and nitrogen in Dunlin muscle tissue were used to determine habitat preference and trophic level, respectively. Cadmium concentrations in kidneys were significantly related to habitat preference: [Cd] in estuarine foragers >[Cd] in terrestrial foragers. Cadmium accumulation was age-dependent as concentrations increased significantly within 10 months of hatch dates but not afterward. Concentrations of cadmium and zinc in kidneys as well as lead and mercury in feathers were below those known to cause deleterious effects in birds. In contrast, selenium concentrations in feathers (range: 2.1-14.0 µg/g) were often at levels associated with toxicity risks (>5 µg/g). Toxicity thresholds are not available for copper in kidneys or copper and zinc in feathers; however, measured concentrations of these elements were within documented ranges for sandpipers. Future studies should assess potential impacts of selenium on embryonic development in Dunlin and other sandpipers. Risk assessments would yield more conclusive results for all elements if impacts under ecologically relevant stresses (e.g. development in the wild, migration, predation) were better understood.

Concentration and partitioning of metals in intertidal biofilms: implications for metal bioavailability to shorebirds.

We compared zinc, copper and cadmium concentrations and the operationally defined geochemical partitioning of the three metals in sediments enriched with biofilm versus sediments without obvious biofilm present (reference) sampled from five locations within the Fraser River Delta, British Columbia, Canada. Two-way ANOVA's with site and biofilm (enriched or reference) as the two factors were applied to determine if metal concentrations or the partitioning of the metal was dependent on the two factors. Sediment enriched in biofilm contained greater amounts of aqua regia extracted zinc and copper and tended to have greater amounts of reducible cadmium as compared to reference sediments. By contrast, reference sediments had greater concentrations of easily reducible copper suggesting differences in speciation between the two sediment types. Greater concentrations of reducible cadmium within biofilm may provide a route of contaminant exposure to shorebirds whose diet is dependent on biofilm.

Legacy metals within urban aquatic environments and the challenge they pose to rehabilitation.

Legacy metals, a result of previous environmentally unsound practices, pose a challenge to the rehabilitation of urban aquatic ecosystems. The current study focuses on a harbor in Vancouver, British Columbia, Canada, where use of antifouling paints for hull cleaning occurred for ca. 30 years. Sediment metal concentrations were mapped by depth and distance from where hulls were cleaned. By relating metal concentrations to the benthic invertebrate community and bivalve metal content, results indicate that cleaning activities severely impacted sediment quality. However, sewer outfalls, which integrate non-point sources of metals to the harbor, also contributed to poor sediment quality and high metal concentrations in bivalves. For the aquatic system to recover, non-point diffuse metal sources must be addressed, regardless of the challenge.

Trace metal depositional patterns from an open pit mining activity as revealed by archived avian gizzard contents.

Archived samples of blue grouse (Dendragapus obscurus) gizzard contents, inclusive of grit, collected yearly between 1959 and 1970 were analyzed for cadmium, lead, zinc, and copper content. Approximately halfway through the 12-year sampling period, an open-pit copper mine began activities, then ceased operations 2 years later. Thus the archived samples provided a unique opportunity to determine if avian gizzard contents, inclusive of grit, could reveal patterns in the anthropogenic deposition of trace metals associated with mining activities. Gizzard concentrations of cadmium and copper strongly coincided with the onset of opening and the closing of the pit mining activity. Gizzard zinc and lead demonstrated significant among year variation; however, maximum concentrations did not correlate to mining activity. The archived gizzard contents did provide a useful tool for documenting trends in metal depositional patterns related to an anthropogenic activity. Further, blue grouse ingesting grit particles during the time of active mining activity would have been exposed to toxicologically significant levels of cadmium. Gizzard lead concentrations were also of toxicological significance but not related to mining activity. This type of "pulse" toxic metal exposure as a consequence of open-pit mining activity would not necessarily have been revealed through a "snap-shot" of soil, plant or avian tissue trace metal analysis post-mining activity.

Sea ducks and aquaculture: the cadmium connection.

Elevated concentrations of cadmium have been reported in the kidneys of sea ducks that forage along the Pacific Northwest, and cadmium has been postulated as a possible cause of population declines. The blue mussel (Mytilus spp.) which occurs in dense numbers on aquaculture structures and are a primary prey item for sea ducks also contain elevated cadmium concentrations. To determine if foraging on mussels associated with aquaculture structures could pose a toxicological risk to sea ducks, amounts of cadmium ingested per body weight per day by a representative sea duck species, the surf scoter (Melanitta perspicillata), were estimated and compared to the reported avian cadmium NOAEL (no observable adverse effect level) and LOAEL (lowest observable adverse effect level). Results indicate that in some locations within the Pacific Northwest, sea ducks could be exposed to toxicologically significant levels of cadmium associated with mussels foraged from aquaculture structures. This raises the possibility that such exposure could be contributing to observed population declines in these species.

Cadmium in shellfish: the British Columbia, Canada experience--a mini-review.

Over 10 years ago, research scientists in the federal department of Fisheries and Oceans Canada (DFO) were alerted to the presence of high levels of cadmium, a toxic metal, in the Pacific oyster (Crassostrea gigas) cultured in British Columbia (BC), Canada waters. This mini-review summarizes the most recent published studies on levels of cadmium in shellfish from the Pacific Northwest (BC and Washington State). Recent health risk assessments with respect to the ingestion of BC oysters are presented. The review concludes with a discussion on the ethical dilemma now facing the shellfish industry in the Pacific Northwest and provides recommendations for the culturing of shellfish without fear of high cadmium levels.

Sources of dietary cadmium to the Pacific oyster Crassostrea gigas.

Oysters from the Pacific north-west coast contain high cadmium concentrations (greater than 13.5 microg g(-1) dry weight), which exceed consumer guidelines for international markets. Oysters are selective filter-feeders and attempts which have focused on suspended particulate matter (SPM) as a means to assess the importance of diet as a route of cadmium exposure have met with limited success. Here we use actual gut contents as an alternate to SPM to assess if this is a better predictor of cadmium exposure to the oyster via the diet. We also applied stable isotope analysis, delta(13)C and delta(15)N, to determine the origin of organic material (from terrestrial to oceanic) ingested by the oyster. Oyster gut and tissue cadmium concentrations and corresponding isotopic signatures were determined every 2-3 months for 22 months from 10 locations on the west coast of B.C. Gut and tissue cadmium concentrations were correlated (r(2)=0.40; p<0.05), suggesting that diet could account for at least 40% of observed cadmium oysters residues. Oyster gut and tissue cadmium concentrations and delta13C and delta15N signatures were region dependent. Oysters from the most marine influenced sites contained gut and tissue cadmium residues of 30.4+/-3.08(S.E.) microg g(-1) and 6.0+/-0.6 microg g(-1), respectively, and a stable isotopic signature typical of marine phytoplankton. In contrast, oysters sampled from regions influenced by coastal processes contained significantly greater concentrations of cadmium, 43.0+/-2.4 microg g(-1) and 10.2+/-0.68 microg g(-1) gut and tissue, respectively, with isotopic signatures representative of terrestrial organic matter. This indicates that diet is an important source of cadmium to oysters from the Pacific north-west, however its importance is region dependent and cannot be simply ascribed to one source of organic matter alone.

Survey of levels of cadmium in oysters, mussels, clams and scallops from the Pacific Northwest coast of Canada.

Field and retail collections of bivalves from the Pacific Northwest, Canada, were analysed for cadmium concentrations by atomic absorption spectrophotometry (AAS). Both collections of varnish (Nuttallia obscurata) and manila (Venerupis philippinarum) clams contained cadmium concentrations of less than 0.5 µg g(-1), well below international safety guidelines of 1 and 2 µg g(-1) wet weight cadmium for the European and Hong Kong markets, respectively, as well as the 2 µg g(-1) safety guideline set by the Codex Alimentarius Commission (CAC). Cadmium concentrations in retail collections of the Pacific oyster, Crassostrea gigas, were generally above 2 µg g(-1) wet weight (range = 1.5-3.56 µg g(-1)). Retail collections of the mussel, Mytilus spp., contained cadmium concentrations below the 2 µg g(-1) wet weight guideline, but not always the 1 µg g(-1) limit (range = 0.15-1.8 µg g(-1)). However, field collections of Mytilus spp. contained cadmium concentrations between 0.35 and 4.00 µg g(-1) wet weight, and depending on sampling location, concentrations exceeded the CAC guidelines by more than two-fold. Locations where mussels had high cadmium concentrations correlated with regions that had previously reported high values for cadmium in Pacific oysters (r = 0.65; p < 0.05). Of the various shellfish analysed, the four species of scallops, Chlamys hastata, C. rubida, Crassadoma gigantea, and Patinopecten yessoensis, contained the greatest concentrations of cadmium, in excess of 5 µg g(-1) wet weight (range = 4.97-8.98 µg g(-1)) with the greatest concentrations determined for C. gigantea. Cadmium concentrations in shellfish from the Pacific Northwest are greater than values reported for shellfish from other regions of the world and consumers need be aware of Health Canada consumption guidelines for shellfish from this region.