Pacific Coast Of Canada Research Articles

Occupancy trends of overwintering coastal waterbird communities reveal guild-specific patterns of redistribution and shifting reliance on existing protected areas.

Climate change and anthropogenic stressors are redistributing species and altering community composition globally. Protected areas (PAs) may not sufficiently protect populations of species undergoing distributional shifts, necessitating that we evaluate existing PAs and identify areas for future protection to conserve biodiversity across regional and temporal scales. Coastal waterbirds are important indicators of marine ecosystem health, representing mobile, long-lived, higher trophic-level consumers. Using a 20-year citizen science dataset (1999-2019) with a before-after control-intervention sampling framework for habitat protection, we applied dynamic occupancy models to assess winter occupancy trends along the Pacific coast of Canada. Specifically, we sought to understand potential drivers of regional declines, spatial commonalities among guilds, and changes in habitat use before and after PA designation, as well as between PAs and non-PAs. Occupancy trends varied regionally, with greater declines in the south compared to the north. Regional differences underlined potential range shifts, particularly for species with traits linked to temperature tolerance, movement, and high productivity foraging, as cold-tolerant, migratory benthivores and piscivores wintered farther north relative to 20 years ago or retreated to cold-water fjords. While 21 of 57 (36.8%) species responded positively to PA designation (before-after), greater occupancy declines tended to occur in PAs established pre-1999 relative to non-PAs (control-intervention). Since PAs are currently concentrated in the south, negative associations were most apparent for species retreating northward, but existing PAs may have a stabilizing or transitory effect on southern wintering species shifting into the region from farther south. We emphasize that conservation strategies must balance persistence of current communities with preserving the climate-adapted biodiversity of tomorrow by accounting for community-level effects of species moving into and out of existing PAs. Incorporating range shifts into PA planning by predicting distributional changes will allow conservation practitioners to identify priority habitats, such as cold-water refugia, for persistent wildlife communities.

Two new species of Callophyllis (Rhodophyta, Kallymeniaceae) from the Russian Pacific coast

ABSTRACT Seven species of Callophyllis have been known off the Pacific coast of Russia; hovewer, molecular data have been obtained only for three species. In this study we re-examined the genus along the Russian Pacific coast using a comparative morphological study and molecular analyses based on rbcL and nrLSU. Five genetic species were identified on the Russian coast based on phylogenetics and species delimitation (ASAP and p-distance) analyses; while C. beringensis, C. papulosa and C. platyna were outscore of the analyses. The results of the molecular analyses uncovered one undescribed species, which we named C. selivanovae sp. nov. The divergence between this species and other species of the genus varied from 1.16% to 5.66%, while intraspecific divergence in the genus was in a range of 0.00%–0.22%. In phylogenetic trees C. selivanovae was recognized as sister to a diverse clade including C. thompsonii, C. beringensis, C. violacea, C. flabellulata and C. variegata from the Pacific coast of Canada. Callophyllis selivanovae from the southeastern coast of Kamchatka is morphologically close to C. beringensis, described from St. Paul Island (Bering Sea); the two species differ in features of branching, shape and size of the terminal branches. We propose a new name, C. perestenkoae sp. nov., for the algae previously listed in the Russian flora as ‘C. flabellata’. Pacific specimens assigned to C. perestenkoae differ from C. flabellata from the type locality (Atlantic, France) in having irregular branching, thicker apical branches, and smaller cystocarps. We also filled in the gaps in the description of C. radula for which procarp and tetrasporangia are described herein for the first time.

Effect of dietary supplementation of probiotic on growth, survival, and immune-related biomarkers in Chinook Salmon (Oncorhynchus tshawytscha) challenged with Vibrio anguillarum

Chinook salmon is a native species of the Canadian Pacific coast with potential economic and environmental benefits for aquaculture. However, its production is jeopardized by low tolerance to high densities and disease susceptibility. Due to this, Chinook salmon represents a great candidate for evaluating the effect of non-polluting alternatives to vaccines and antibiotics, such as probiotics. Preliminary studies have suggested that certain probiotic strains may be able to enhance fish growth, antioxidant activity, food digestibility, modulate the host microbial community in the digestive tract, and prevent bacterial infections. However, there is currently no evidence of its effects in Chinook salmon. Here, we used the commercially available, low-cost multi-strain probiotic used by humans, to determine the impact on Chinook salmon growth, survival, immune response, and gut barrier integrity. Fish were randomly assigned to four netpens and given either regular (control) feed or supplemented with probiotics for 4, 10, or 14 months. After this, fish were transferred to troughs and challenged with Vibrio anguillarum. Probiotic supplementation for 14 months decreased mortality by ∼10% compared to the control treatment. However, no positive effects of this probiotic supplementation on fish growth occurred. Despite the improvement in survival associated to long-term probiotic supplementation, the expression of the immune genes il1b, il8, il10, tnfa, camp, hamp, and transferrin in head kidney, spleen, and hindgut tissues did not fully provide the specific innate immune mechanisms that could be associated with a better protection. Decreased expression of cldn1 and ocln in fish supplemented for 14 months compared to 4- and 10-months suggested that probiotic treatment during the freshwater and saltwater cycle confers a better protection and intestinal integrity, resulting in an improved survival. Although it was not possible to observe differences in IgM and IgT protein levels between probiotic-supplemented fish and the control treatment in plasma, head kidney, spleen, and hindgut, this study represents the first measurement of total IgT protein levels in Chinook salmon. In summary, probiotic supplementation modulated the early inflammatory response against V. anguillarum infection and helped improve the survival of Chinook salmon aquaculture in an environmentally sustainable manner when applied in freshwater and up to the transition to saltwater growth phase.

Marine spatial planning for connectivity and conservation through ecological corridors between marine protected areas and other effective area-based conservation measures

Maritime Spatial Planning (MSP) promotes the sustainable human activities development and uses in the marine space, playing a role in their effective management. The enhancement of connectivity is crucial for the conservation of biodiversity and landscape planning. Ecological Corridors (ECs) are an important type of connectivity for biodiversity conservation in fragmented habitats. The EU Biodiversity Strategy 2030 includes ECs into the network of protected areas and allows for the creation of additional protected areas. MSP studies considering ECs remain still lacking, especially for the design of networks between Marine Protected Areas (MPAs) and Other Effective area-based Conservation Measures (OECMs). In this paper, knowledge, and tools for investigating marine ECs were reviewed, with a systematic bibliometric analysis to summarize the current scientific research. Previous studies integrating ecological connectivity into planning for marine conservation have focused on models of larval dispersal, adult movements, and dispersal of single species by using benthic habitat proxies. Few studies were found on ECs in marine environments: in the coral Caribbean reef systems in the Gulf of Mexico; within benthic habitats along the Pacific coast of Canada; between MPAs in British Columbia (Canada); and by analyzing migratory species in the Yangtze estuary (China). Commonly used approaches to project and map ECs in marine environments are least-cost and circuit theories allowing to incorporate movement with cost or resistance to movement, depending on species and preferred habitats. The systematic bibliometric analysis returned 25 studies, most of which were from North America (40%) and European countries (36%) and the largest share of papers (68%) from 2018 to 2022. This review pinpointed the need of integrating different disciplines to investigate connectivity and the need by policymakers and practitioners to recognize the importance of ecological connectivity, even there are significant challenges for integrating connectivity into policies, planning, and conservation.

Extreme Sea Levels and Their Attribution for the Canadian Pacific Coast From a Baroclinic Regional Ocean Model and Tide‐Gauge Data

AbstractThe existing operational storm surge model for the Canadian Pacific coast is barotropic without coupling with tides. Here a baroclinic ocean model, which includes tides, storm surges, intra‐seasonal, seasonal, and interannual variations, is developed to reproduce coastal sea levels in the northeast Pacific from 1993 to 2020. The model results are validated against observations at tide‐gauge sites, demonstrating overall good skills for tides and non‐tidal sea levels. The Gumbel distribution is applied to derive extreme sea levels from hourly sea level anomalies. The model‐based extreme sea levels agree approximately with the observation‐based ones. For the 100‐year return period, modeled total extreme sea levels range from 2.14 m at Victoria Harbour to 4.43 m at Queen Charlotte City, and modeled non‐tidal extreme sea levels from 1.02 m at Bella Bella to 1.78 m at Queen Charlotte City. On average, the model‐based values underestimate the 100‐year return level by 0.18 m for total extreme sea levels and by 0.23 m for non‐tidal extreme sea levels. Both the model‐ and observation‐based results reveal that the storm surge at periods less than 10 d accounts for 60% of the 100‐year non‐tidal extreme sea level, and the intra‐seasonal, seasonal, and interannual variations account for 40% of it. The present study improves coastal sea level modeling and model‐based extreme level estimates. Moreover, this study also demonstrates for the first time that the intra‐seasonal to interannual changes contribute substantially to extreme sea levels and that El Niño can enhance this contribution on the Canadian Pacific coast.

Urban Flooding in Vancouver, Canada

Flooding can have devastating, long-lasting, and costly consequences, including the loss of life and displacement of communities. This review report summarizes the background, causes, and management practices of various urban flooding forms and mitigation efforts in Vancouver, British Columbia (BC) which is located on the Western part on the Pacific coast of Canada. The report makes use of existing literature to understand the flooding phenomena in Vancouver. The city is unique from a flood planning or management perspective because the city is vulnerable to every type of major flooding event, including pluvial, fluvial, and coastal flooding. Nevertheless, Vancouver is considered a globally sustainable city. As such, this report reviews various articles and research to determine the background and causes of various forms of floods experienced in Vancouver and the management practices put in place to mitigate flooding in the city. The study identifies measures in place to address every type of flooding event.

A Multi-Satellite Mapping Framework for Floating Kelp Forests

Kelp forests provide key habitat on the Pacific Coast of Canada; however, the long-term changes in their distribution and abundance remain poorly understood. With advances in satellite technology, floating kelp forests can now be monitored across large-scale areas. We present a methodological framework using an object-based image analysis approach that enables the combination of imagery from multiple satellites at different spatial resolutions and temporal coverage, to map kelp forests with floating canopy through time. The framework comprises four steps: (1) compilation and quality assessment; (2) preprocessing; (3) an object-oriented classification; and (4) an accuracy assessment. Additionally, the impact of spatial resolution on the detectability of floating kelp forests is described. Overall, this workflow was successful in producing accurate maps of floating kelp forests, with global accuracy scores of between 88% and 94%. When comparing the impact of resolution on detectability, lower resolutions were less reliable at detecting small kelp forests in high slope areas. Based on the analysis, we suggest removing high slope areas (11.4%) from time series analyses using high- to medium-resolution satellite imagery and that error, in this case up to 7%, be considered when comparing imagery at different resolutions in low–mid slope areas through time.

Polycyclic aromatic compound and trace metal element residues in Mytilus mussels at marine wildlife hotspots on the Pacific coast of Canada

The Pacific coast of Canada has a rich marine fauna and a growing human population with increasing potential for pollution releases, but there is currently little overlap between marine wildlife hotspots and ongoing biomonitoring efforts for less bioaccumulative contaminants such as polycyclic aromatic compounds (PAC) and trace metals (metals). We surveyed PACs and metals at marine bird breeding colonies in coastal British Columbia in 2018 by analyzing chemical residues in the soft tissue of bivalve Mytilus sp. mussels collected from stations (n = 3) at seven sites. The concentration of sum PACs (∑43PAC) and high molecular weight (HMW) PACs were highest at the Second Narrows colony in Vancouver Harbour, a highly urbanized and industrialized port within the Salish Sea. For conservation areas, two Salish Sea and three Pacific Ocean coast colonies, PACs were generally lower. However, ∑43PAC, ∑HMWPAC, and several HMW congeners at the remote site of Triangle Island, a Marine National Wildlife Area, were not significantly different from Second Narrows. The dominant PAC sources at all sites are likely pyrogenic rather than petrogenic, as suggested by PAC profiles, proportion of parent PACs, and source-indicator congeners. For metals, site differences were found for seven out of eight priority metals, but principal component analysis indicated that site differences, such as high mercury and cadmium at offshore sites, are likely related to environmental and biological variables including salinity, condition index, water temperature, and shell length. Our survey across a broad coastal region shows that PAC and metal biomonitoring programs with mussels should include wildlife hotspots where the exposure of protected vertebrate species to pollutants with low bioaccumulation potential would be less obvious, and shows that collection of data on key covariates (e.g. lipid content, salinity) will be critical to tracking long-term trends and detecting pollution release events.

Using Bayesian networks to map winter habitat for mountain goats in coastal British Columbia, Canada

The mountain goat (Oreamnos americanus) is an iconic wildlife species of western North America that inhabits steep and largely inaccessible terrain in remote areas. They are at risk from human disturbance, genetic isolation, climate change, and a variety of other stressors. Managing populations is challenging and mountain goats are particularly difficult and expensive to inventory. As a result, biologists often rely on models to estimate the species’ abundance and distribution in remote areas. We used landscape characteristics evident at point locations of mountain goat visual observations, tracks, and telemetry locations, along with random locations, to learn the structure and parameters of a Bayesian network that predicted the suitability of habitats for mountain goats. We then used the model to map habitat suitability across 285,000 km2 of potential habitat in mountain ranges of the south and central Canadian Pacific coast. Steep slopes, forest cover characteristics, and snow depth were the important drivers. Modeling the system as a Bayesian network provided several advantages over more common regression methods because input variables were heterogenous (i.e., a mix of discrete and continuous), autocorrelated, and animals exhibited non-linear responses to landscape conditions. These common characteristics of ecological data routinely violate the assumptions of parametric linear models, which are commonly used to map habitat suitability from animal observations.

Stochastic source modeling and tsunami simulations of cascadia subduction earthquakes for Canadian Pacific coast

ABSTRACT This study presents new stochastic source models for the Cascadia subduction earthquakes in the Pacific Northwest, which can trigger massive tsunamis along the shoreline of Vancouver Island. An extensive set of 5,000 stochastic source models is generated for the moment magnitude ranges between 8.1 and 9.1, and regional tsunami hazard simulations are performed at the grid resolution of 270 m. The results from the stochastic tsunami simulations are characterized by evaluating the regional tsunami hazard metric that is based on the geometric mean of the maximum wave heights along the Vancouver Island coast. Subsequently, using the probability distribution of the regional tsunami hazard parameter, representative source models are identified by capturing the average as well as rare rupture cases and then detailed tsunami hazard results, such as maximum wave height maps and wave profiles at specific locations, are examined. Numerical results highlight the directivity effects of tsunami generation and wave propagation on tsunami hazards along the Canadian Pacific coast and the earthquake source characterizations in terms of fault geometry and earthquake slip distribution. The developed source models and tsunami simulation results serve as the first step for performing probabilistic tsunami hazard analysis for the Cascadia subduction zone.

Using successional drivers to understand spatiotemporal dynamics in intertidal mudflat communities

AbstractElucidating factors (“drivers”) that influence succession after disturbance can explain ecological phenomena, including why communities vary spatiotemporally. To gain insight on drivers related to habitat availability, species availability, and species performance during succession, we conducted two field experiments on infaunal communities in intertidal mudflats, one on each of the Atlantic and Pacific coasts of Canada, that had disturbances of different type, size, and frequency. Related to habitat availability drivers, we observed that disturbance type and size, which differed between experiments, did not change end patterns of succession; however, disturbance frequency, directly assessed in one experiment, did. Dispersal of species from surrounding mudflat and water column (species availability) was the primary driver of succession, whereas local interactions between species after colonization (species performance drivers) did not have a detectable effect. We suggested that ample space and resources diffused competition and predation effects, and so species replacements did not occur in our systems, resulting in a lack of “traditional” successional dynamics as observed in other ecosystems. Our findings that community composition in intertidal mudflats is strongly influenced by species availability on two different coasts suggest that this driver may be key to variation in intertidal mudflat communities elsewhere.

Wind-driven upwelling and surface nutrient delivery in a semi-enclosed coastal sea

Abstract. Wind-driven upwelling is an important control on surface nutrients and water properties in stratified lakes and seas. In this study, a high-resolution biophysical coupled model is used to investigate upwelling in the Strait of Georgia on the Canadian Pacific coast. The model is forced with surface winds from a high-resolution atmospheric forecast and has been tuned in previous studies to reproduce extensive observations of water level, temperature, salinity, nutrients and chlorophyll with competitive skill relative to similar models of the study region. A total of 5 years of hourly surface nitrate and temperature fields are analyzed in order to characterize the dominant upwelling patterns of the basin. A prevailing along-axis wind pattern steered by mountainous topography produces episodic upwelling along the western shore during the spring and fall southeasterlies and along the eastern shore during the summer northwesterlies, as indicated by positive nitrate anomalies. Principal component analysis reveals that these cross-axis upwelling patterns account for nearly one-third of the surface nitrate variance during the summer productive season. By contrast, nearly half of the surface temperature variance over the same period is dominated by a single, combined mixing and diurnal heating–cooling pattern. The principal components associated with these patterns correlate with along-axis wind stress in a manner consistent with these physical interpretations. The cross-axis upwelling response to wind is similar to other dynamically wide basins where the baroclinic Rossby deformation radius is smaller than the basin width. However, the nitrate anomaly during upwelling along the eastern shore is stronger in the northern basin, which may be indicative of an along-axis pycnocline tilt or an effect of the background along-axis stratification gradient due to the Fraser River. Our findings highlight an important spatiotemporal consideration for future ecosystem monitoring.

Using aerial surveys to fill gaps in AIS vessel traffic data to inform threat assessments, vessel management and planning

AIS (Automatic Identification System) is a widely used source of data to spatially and temporally characterize marine vessel traffic and to subsequently estimate the direct and indirect threats maritime activities pose to marine and coastal environments. However, AIS data do not capture all vessel traffic in an area because not all vessels (e.g., recreational vessels) are required to carry AIS transponders. The goal of this study is to quantify the proportion of vessel traffic not transmitting AIS data by employing dedicated aerial surveys that simultaneously capture AIS data and georeferenced imagery of non-AIS vessels on the Canadian Pacific coast. Results show that 70% of vessel traffic in the surveyed area do not transmit AIS. The majority of these non-AIS vessels are recreational, making up 53% of the total vessels sighted. Analysis of historical AIS data in the survey area shows a steady increase in the voluntary uptake of AIS in the last decade. Results of this study can be used to adjust vessel traffic estimates and associated threats that are exclusively based on AIS data. This information can also benefit managers and policy makers that rely on AIS data when developing vessel traffic management measures to mitigate threats and to inform regional marine spatial plans. Place-specific studies to quantify marine vessel traffic missed by AIS are encouraged in coastal areas with high density of small vessel traffic.

Changes to the 1979–2013 summer Convective Available Potential Energy (CAPE) and extreme precipitation over North America

Trends of monthly Convective Available Potential Energy (CAPE) and of single or multiple event extreme precipitation indices, namely RX1day, RX5day and R20mm, were analyzed for the summer of 1979–2013 over the United States (US) and southern Canada. A homogeneity test in CAPE data using the Wilcoxon-rank-sum test showed that statistically significant change points mainly occurred between 2000 and 2003 probably due to changes in humidity sensors during this period. Therefore, the trend analysis was split into two categories: 1979–2013 for regions where no statistically significant change points in CAPE were detected and 1979–2001 and 2002–2013 for regions where statistically significant change points in CAPE were detected. The results show that increasing trends in CAPE and extreme precipitation indices dominate the eastern Atlantic coast of the US and some parts of the Great Lakes. Mixed increasing and decreasing trends were detected in the US mid-west while the western US and the Canadian Pacific coast had little trend in CAPE and extreme precipitation indices. Although both increasing and decreasing trends were detected, the average trends in RX1day and RX5day were about 0.2 mm/decade and 0.5 mm/decade over 1979–2013. However, the average trend for the 1979–2001 period was 0.2 mm/decade (RX1day) and 1.2 mm/decade (RX5day) as compared 1.2 mm/decade (RX1day) and 1.7 mm/decade (RX5day) for the 2002–2013 period. Temperatures also increased more during the 2002–2013 period (0.3 °C/decade) as compared to the 1979–2001 period (0.1 °C/decade). The higher increasing trend of the recent decades suggests that increasing temperatures could potentially lead to an overall increase in CAPE and extreme precipitation over the US and southern Canada.

Access rights, capacities and benefits in small-scale fisheries: Insights from the Pacific Coast of Canada

Small-scale fisheries depend on availability of and access to resources. Yet research on access – the combination of rights and capacities that enable fishers to benefit from available resources – has been limited compared to research on availability in Canadian fisheries. We surveyed 118 independent fishers in British Columbia, Canada to understand access rights (harvesting, entrance, transferability, security and protection), capacities (physical, human, social, cultural, political and financial assets), economic benefits from fishing, and actions to maintain or increase access. Participants generally perceived: strengths in physical, human and cultural assets; varied status in social and financial assets; and weaknesses in political assets. Access rights were generally perceived as poor with the exception of transfer rights. We employed modeling approaches to understand demographic characteristics of participants with higher rights and capacity, and which factors predicted feasibility and economic benefits of fishing. Higher perceived rights and capacities were both predicted by whether the participant self-identified as Indigenous. Higher feasibility of fishing was associated with higher political and financial assets, higher rights, being non-Indigenous, rural residence, and higher incomes. Higher income from fishing was predicted by higher financial assets and being non-Indigenous. Qualitative results showed participants maintain or gain access through: preparation; non-political networking; political advocacy; augmenting licenses or quota; or, diversification and intensification of fishing activities. Yet, many participants reported feeling powerless. Our research emphasizes the need to address access in fisheries management. Our novel conceptualization and mixed methods approach to study access rights and capacities can be adapted and applied elsewhere.

Factors affecting the seasonal distribution and biomass of E. pacifica and T. spinifera along the Pacific coast of Canada: A spatiotemporal modelling approach.

Euphausiids are a keystone species in coastal food webs due to their high lipid content and seasonally high biomass. Understanding the habitat and environmental drivers that lead to areas of high biomass, or ‘hotspots’, and their seasonal persistence, will support the identification of important foraging regions for mid- and upper- trophic level predators. We quantify the distribution of hotspots of the two dominant species of euphausiid in the north-east Pacific Ocean: Euphausia pacifica and Thysanoessa spinifera, as well as euphausiid larvae (mixed species). The Canadian coast encompasses the northern California Current Ecosystem and the transition zone to the Alaska current, and is a highly productive region for fisheries, marine mammals, and seabirds. We used spatiotemporal modelling to predict the distribution of these three euphausiid groups in relation to geomorphic and environmental variables during the important spring-summer months (April through September) when euphausiid biomass is highest. We quantified the area, intensity, and persistence of biomass hotspots across months according to specific oceanographic ecosections developed for marine spatial planning purposes. Persistent hotspots of both adult species were predicted to occur along the 200 m depth contour of the continental slope; however, differences were predicted on the shallower Dixon shelf, which was a key area for T. spinifera, and within the Juan de Fuca Eddy system where E. pacifica hotspots occurred. The continental slope along the west coast of Vancouver Island was the only persistent hotspot region common between both adult species and euphausiid larvae. Larval distribution was more correlated with T. spinifera than E. pacifica biomass. Hotspots of adults were more persistent across months than hotspots of euphausiid larvae, which were seasonally patchy. The persistence of biomass hotspots of forage species through periods of low overall biomass could maintain trophic connectivity through perturbation events and increase ecosystem resilience to climate change.

Draft Genome Sequence of an Aeromonas salmonicida subsp. salmonicida Strain from the Canadian Pacific Coast Bearing a Variant of pRAS1.

The genome sequencing of Aeromonas salmonicida subspecies salmonicida strain 2004-072 revealed a plasmid bearing a region carrying antibiotic resistance genes very similar to the one found in the plasmid pRAS1, an IncU family plasmid. This new plasmid was named pRAS1b.

Exposure to persistent organic pollutants is linked to over-wintering latitude in a Pacific seabird, the rhinoceros auklet, Cerorhinca monocerata.

Seabirds are wide-ranging organisms often used to track marine pollution, yet the effect of migration on exposure over the annual cycle is often unclear. We used solar geolocation loggers and stable isotope analysis to study the effects of post breeding dispersal and diet on persistent organic pollutant (POP) and mercury (Hg) burdens in rhinoceros auklets, Cerorhinca monocerata, breeding on islands along the Pacific Coast of Canada. Hg and four classes of POPs were measured in auklet eggs: organochlorine insecticides (OCs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and perfluoralkyl substances (PFASs). Stable isotope values of adult breast feathers grown during winter were used in conjunction with geolocation to elucidate adult wintering latitude. Wintering latitude was the most consistent and significant predictor of some POP and of Hg concentrations in eggs. The magnitude and pattern of exposure varied by contaminant, with ∑PCBs, ∑PBDEs and DDE decreasing with wintering latitude, and mirex, perfluoro-n-tridecanoic acid, and Hg increasing with latitude. We suggest that concentrations of these contaminants in rhinoceros auklet eggs are influenced by variation in uptake at adult wintering locations related to anthropogenic inputs and oceanic and atmospheric transport.

Future Changes in Oceanography and Biogeochemistry Along the Canadian Pacific Continental Margin

Model projections of ocean circulation and biogeochemistry are used to investigate large scale climate changes under moderate mitigation (RCP 4.5) and high emissions (RCP 8.5) scenarios along the continental shelf of the Canadian Pacific Coast. To reduce computational cost, an approach for dynamical downscaling of climate projections was developed that uses atmospheric climatologies with augmented winds to simulate historical (1986–2005) and future (2046–2065) periods separately. The two simulations differ in initial and lateral open boundary conditions. For each simulation, the daily climatology of surface winds in the driving model was augmented with high-frequency variability from an atmospheric reanalysis product. The “time-slice” approach was able to reproduce the observed climate state for the historical period. Sensitivity tests confirmed that the high frequency wind variability plays an essential role in freshwater distribution in this region. Projections suggest that sea surface temperature will increase by 1.8–2.4°C and surface salinity will decrease between −0.08 and −0.23 depending on whether a moderate or high emissions scenario is used. Stratification increases throughout the region and there is some evidence of nutrient limitation near the surface. Primary production and phytoplankton productivity (chlorophyll) also increase. Density surfaces are relocated deeper in the water column and this change is mainly driven by surface heating and freshening. Changes in saturation state are mainly due to anthropogenic CO2with minor contributions from solubility, remineralization and advection. There is little difference between RCP 4.5 and RCP 8.5 with regard to projections of deoxygenation and acidification. The depths of the aragonite saturation state and the oxygen minimum zone are projected to become shallower by ≃ 100 and ≃ 75 m respectively. Extreme states of temperature, oxygen and acidification are projected to become more frequent and more extreme, with the frequency of occurrence of[O2]<60 mmolm-3expected to approximately double under either scenario.

Hydroclimatic trends during 1950–2018 over global land

Global hydroclimatic changes from 1950 to 2018 are analyzed using updated data of land precipitation, streamflow, and an improved form of the Palmer Drought Severity Index. The historical changes are then compared with climate model-simulated response to external forcing to determine how much of the recent change is forced response. It is found that precipitation has increased from 1950 to 2018 over mid-high latitude Eurasia, most North America, Southeast South America, and Northwest Australia, while it has decreased over most Africa, eastern Australia, the Mediterranean region, the Middle East, and parts of East Asia, central South America, and the Pacific coasts of Canada. Streamflow records largely confirm these precipitation changes. The wetting trend over Northwest Australia and Southeast South America is most pronounced in austral summer while the drying over Africa and wetting trend over mid-high latitude Eurasia are seen in all seasons. Coupled with the drying caused by rising surface temperatures, these precipitation changes have greatly increased the risk of drought over Africa, southern Europe, East Asia, eastern Australia, Northwest Canada, and southern Brazil. Global land precipitation and continental freshwater discharge show large interannual and inter-decadal variations, with negative anomalies during El Nino and following major volcanic eruptions in 1963, 1982, and 1991; whereas their decadal variations are correlated with the Interdecadal Pacific Oscillation (IPO) with IPO’s warm phase associated with low land precipitation and continental discharge. The IPO and Atlantic multidecadal variability also dominate multidecadal variations in land aridity, accounting for 90 % of the multidecadal variance. CMIP5 multi-model ensemble mean shows decreased precipitation and runoff and increased risk of drought during 1950–2018 over Southwest North America, Central America, northern and central South America (including the Amazon), southern and West Africa, the Mediterranean region, and Southeast Asia; while the northern mid-high latitudes, Southeast South America, and Northwest Australia see increased precipitation and runoff. The consistent spatial patterns between the observed changes and the model-simulated response suggest that many of the observed drying and wetting trends since 1950 may have resulted at least partly from historical external forcing. However, the drying over Southeast Asia and wetting over Northwest Australia are absent in the 21st century projections.