Southern Vancouver Island Research Articles

Cougar spatiotemporal response to human activities in a multi‐use forest landscape on southern Vancouver Island

Recreational activities have been shown to induce fear responses in carnivores, causing both spatial and temporal displacement that can have cascading effects on the wider ecological community. Cougars Puma concolor are one species that are particularly sensitive to human disturbances as they have been found to be impacted by various forms of recreational activities. This research aimed to quantify the spatial and temporal responses of cougars to human activities on southern Vancouver Island in British Columbia, Canada. Fifty camera traps were deployed in a systematic probabilistic sampling design and data from the summer season of 2022 was used for analyses. We modeled cougar weekly occurrence frequency in relation to human (hikers and bikers) occurrence frequency, vehicle occurrence frequency, and landscape features, using generalized linear mixed models. Temporal responses of cougars were investigated using activity pattern analysis to compare activity patterns within a recreation area and a restricted public access reserve. Cougars avoid occurring at sites where recreationalists frequently visited, but not sites frequented by vehicles on unpaved roads. We observed minimal influence of habitat features or prey availability on cougar occurrence frequency, as measured by information loss (AICc scores). Activity pattern analysis did not demonstrate significant differences in cougar daily activity patterns between the recreation area and no‐entry reserve, suggesting a lack of temporal response. These results suggest recreational activities on southern Vancouver Island are impacting cougar spatial – but not temporal – behavioral dynamics. Insights on how cougars respond to recreational activities can help inform landscape management and policies by providing information that can be used to mitigate negative impacts and thus ensure that recreational activities are remaining compatible with conservation efforts.

Detection of Hidden Low-Frequency Earthquakes in Southern Vancouver Island with Deep Learning

Low-frequency earthquakes (LFEs) are small-magnitude earthquakes that are depleted in high-frequency content relative to traditional earthquakes of the same magnitude. These events occur in conjunction with slow slip events (SSEs) and can be used to infer the space and time evolution of SSEs. However, because LFEs have weak signals, and the methods used to identify them are computationally expensive, LFEs are not routinely cataloged in most places. Here, we develop a deep-learning model that learns from an existing LFE catalog to detect LFEs in 14 years of continuous waveform data in southern Vancouver Island. The result shows significant increases in detection rates at individual stations. We associate the detections and locate them using a grid search approach in a 3D regional velocity model, resulting in over 1 million LFEs during the performing period. Our resulting catalog is consistent with a widely used tremor catalog during periods of large-magnitude SSEs. However, there are time periods where it registers far more LFEs than the tremor catalog. We highlight a 16-day period in May 2010, when our model detects nearly 3,000 LFEs, whereas the tremor catalog contains only one tremor detection in the same region. This suggests the possibility of hidden small-magnitude SSEs that are undetected by current approaches. Our approach improves the temporal and spatial resolution of the LFE activities and provides new opportunities to understand deep subduction zone processes in this region.

“We are an active family”: a randomized trial protocol to evaluate a family-system social identity intervention to promote child physical activity

BackgroundRegular engagement in moderate-to-vigorous physical activity (MVPA) during childhood yields a myriad of health benefits, and contributes to sustained MVPA behaviors into adulthood. Given the influence of parents on shaping their child’s MVPA behaviour, the family system represents a viable target for intervention. The purpose of this study is to compare the effects of two intervention conditions designed to increase child MVPA: (1) A standard education + planning intervention providing information about benefits, action planning, and coping planning; and (2) An augmented physical activity education + planning intervention that includes the components of the standard intervention, as well as a focus on family identity promotion and developing as an active member of the family.MethodsA two-arm parallel single-blinded randomized trial will compare the two conditions over 6 months. Eligible families have at least one child aged 6–12 years who is not meeting the physical activity recommendations within the Canadian 24-Hour Movement Guidelines (i.e.,<60 min/day of MVPA). Intervention materials targeting family identity promotion will be delivered online via zoom following baseline assessment, with booster sessions at 6-weeks and 3-months. Child MVPA will be measured by wGT3X-BT Actigraph accelerometry at baseline, 6-weeks, 3-months, and 6-months as the primary outcome. At these same time points, parent cognition (e.g., attitudes, perceived control, behavioral regulation, habit, identity) and support behaviours, and parent-child co-activity will be assessed via questionnaire as secondary outcomes. Child-health fitness measures will be also administered through fitness testing at baseline and 6-months as secondary outcomes. Finally, upon completion of the trial’s 6-month measures, a follow-up end-of-trial interview will be conducted with parents to examine parents’ experiences with the intervention.ResultsSo far, 30 families have been enrolled from the Southern Vancouver Island and Vancouver Lower Mainland area. Recruitment will be continuing through 2026 with a target of 148 families.DiscussionThis study will contribute to the understanding of effective strategies to increase child physical activity by comparing two intervention approaches. Both provide parents with education on physical activity benefits, action planning, and coping planning supports. However, one intervention also incorporates components focused on promoting an active family identity and involving all family members in physical activity together. The findings from this study have the potential to inform the design and implementation of public health initiatives aimed at improving physical activity participation in children and guide the development of more effective interventions that leverage the crucial role of parents and the family system in shaping children’s physical activity behaviors.Trial RegistrationThe clinical trial registration ID is NCT05794789. This trial was registered with clinicaltrials.gov on March 2nd, 2023, with the last updated release on September 28th, 2023.

Conservation genetics of Roosevelt elk: population isolation and reduced diversity

Species reintroductions have the potential to cause genetic bottleneck events resulting in increased genetic drift, increased inbreeding, and reduced genetic diversity creating negative fitness consequences for populations. Roosevelt elk ( Cervus canadensis roosevelti Erxleben, 1777) are “at risk” in British Columbia (BC), Canada. Once widespread along the west coast, Roosevelt elk were likely extirpated from the mainland by 1900 and experienced a substantial population bottleneck on Vancouver Island at that time, and again in the 1950s. Reintroduced to the mainland from Vancouver Island in the 1980s, this re-established population became the source for subsequent mainland translocations. To understand the effects of reintroduction strategy on genetic diversity, we analyzed genetic variation in 355 Roosevelt elk from Vancouver Island and mainland BC. Using mitochondrial DNA and 10 microsatellite loci, molecular analyses showed overall reduced genetic diversity relative to other extant elk populations, genetic isolation of the southern Vancouver Island population, and increased genetic drift among reintroduced herds. Four reintroduced populations were found to have increased levels of inbreeding. Results of this study contribute to our knowledge of reintroduction biology and can be used to guide continued conservation and management of at-risk species.

First report of Leptoglossus occidentalis (Hemiptera: coreidae) feeding on Rubus (Rosaceae) fruit

Abstract The western conifer seed bug, Leptoglossus occidentalis Heidemann (Hemiptera: Coreidae), feeds extensively on the seeds of conifer trees within both its endemic range west of the Rocky Mountains and its expanding introduced range throughout eastern North America, South America, Europe, and Asia. Its damage to conifer seed challenges seed production in natural stands and in orchards that produce seed for forest regeneration and food. In summer 2023, hundreds of L. occidentalis adults were observed feeding on the berries of two cultivated blackberry, Rubus fruticosus Linnaeus (Rosaceae), vines on southern Vancouver Island, British Columbia, Canada. The adults were observed over a period of approximately six weeks, and their stylets were seen penetrating drupelets and causing subsequent damage. Identification was confirmed based on morphological and molecular (CO1 DNA barcoding) methods. To our knowledge, this is the first verifiable report of L. occidentalis feeding on a Rosaceae host, suggesting the insect’s potential for damaging agricultural systems.

Separation of an Upwelling Current Bounding the Juan de Fuca Eddy

AbstractObservations of temperature, salinity, and oxygen on the southern Vancouver Island shelf show a large‐scale exchange of shelf water with offshore water, just offshore of a semi‐permanent recirculation, often termed the Juan de Fuca Eddy. The Eddy occupies a region where the shelf widens abruptly in the lee of a bank. The water in this Eddy is a mixture of offshore water and water from a buoyant coastal current. This water is well‐mixed along a mixing line in temperature‐salinity space, though it retains stratification, and is either rapidly mixed or has a long residence time. There is a less than 1 km wide temperature‐salinity front on the offshore side of this well‐mixed water that has no sign of instabilities. The clearest evidence of cross‐front transport is found during a tidally resolved survey over a bank. The transport is due to flows in the cross‐bank direction that also drive 50 m tall hydraulic jumps. Upstream of the Eddy, there is an along‐shelf current flowing equatorward. However, the whole current separates from the shelf before reaching the Eddy, in the lee of a bank, and is replaced by water from offshore. The separation event was also seen in sea‐surface temperatures from satellite images as a tongue of cool coastal water that is ejected offshore.

Abundance, range and movements of a feeding aggregation of gray whales (Eschrichtius robustus) from California to southeastern Alaska in 1998

This study documents the range, abundance and movements of a feeding aggregation of gray whales (Eschrichtius robustus) in the Pacific northwest. Identification photographs were collected by eight collaborating organisations between March and November 1998. Surveys extended between northern California and southeastern Alaska. Effort was variable by region and was concentrated off the northern Washington coast and Vancouver Island. Of 1,242 occasions when suitable photographs of gray whales were obtained in 1998, 155 unique whales were identified. Each individual was photographed an average of 8.0 times (SD = 8.4, range 1-42) and the average tenure of whales seen multiple times was 56 days (SD = 41, range 1-170). Whales seen longer than three months generally were seen in multiple regions. Movements among regions in 1998 were documented for 57 whales with the most frequent interchange among three adjacent areas from northern Washington to central Vancouver Island. The overall pattern of movements among regions was complex; whales were not always moving in the same direction at the same time of year. Movements within 1998 among more distant locations did occur but were less frequently observed. Total distances between resighting positions for individual whales ranged from &lt; 1 to 526 n.miles. Most whales photographed in 1998 had been identified in previous years when compared to photographs collected by some of the collaborators. At least 86 (55%) of the whales identified had been seen previously. The rate of inter-year resightings was highest for whales identified off northern Washington and three areas off British Columbia (from southern Vancouver Island to north of Vancouver Island). In these areas, from 70-100% of the whales seen in each region had been photographed previously. Mark-recapture abundance estimates based on comparisons to samples in 1996 and 1997 were 181 and 179, respectively. The management implication for these whales has become controversial due to the resumption of whaling by the Makah tribe in northern Washington, an area used by both migrating and feeding whales. This research shows that there are a few hundred gray whales that range in summer months from at least northern California to southeastern Alaska. The mechanism by which these animals are recruited into this group and the degree to which they should be managed as a separate unit from the overall population is not resolved.

They mostly come at night: Predation on sleeping insects by introduced candy-striped spiders in North America.

They mostly come at night: Predation on sleeping insects by introduced candy-striped spiders in North America.

Tackling the challenges of tectonic tremor localization using differential traveltimes and Bayesian inversion

SUMMARY Episodic tremor and slip events in Northern Cascadia produce low-frequency, emergent seismic signals, often referred to as tectonic tremor. Methods designed to locate tremor face two challenges that increase the likelihood of producing low quality catalogues: first, signal arrival and duration are often poorly defined; second, high rates of tremor activity during episodes can cause multiple signals to be indiscernible from each other. In this paper, we present a new method of locating tectonic tremor using differential traveltimes from a waveform-envelope cross-correlation in a grid-based Bayesian inversion. To address the aforementioned challenges, we use a recently developed three-dimensional shear wave velocity model to compute traveltimes, and include processes to remove data outliers, estimate data error statistics, and quantify uncertainties within the Bayesian framework. Although this method is designed for tremor, to test the approach we consider a set of 58 local earthquakes between magnitudes −0.07 and 2.6 in the Southern Vancouver Island region and obtain well-constrained relocations. Residuals between official catalogue values and our relocations are quantized with respect to the 1 km grid resolution of the inversion, and average 2.7 km in epicentre and 5.2 km in depth. Analysis shows that depths of relocations are sensitive to horizontal variations and simplifications in velocity models. We then present our catalogue of tremor events during the 2004 episodic tremor and slip event beneath Southern Vancouver Island, Canada. Median uncertainties of tremor events quantified by 95 per cent credibility interval widths in a 1 km grid are 5 km and 9.km in horizontal and depth directions, respectively (1.2 km and 2.3 km using traditional standard deviation-based uncertainties). Comparison of our catalogue with previously published work demonstrates that our new method yields a good detection rate, a greater degree of epicentral clustering, and better depth resolution of tremor events. Catalogues produced using this new method may help to provide insight into the spatial extent of tremor, especially in depth, by yielding enhanced constraints on source locations on a regional scale.

Evidence of successful hatching by introduced Red-eared Slider (&lt;i&gt;Trachemys scripta elegans&lt;/i&gt;) in British Columbia, Canada

Globally, competition and disease from introduced Red-eared Slider (Trachemys scripta elegans) is a threat to co-existing native turtles. Red-eared Slider has been introduced throughout south coastal British Columbia (BC), mainly as pet turtle releases. Urban centres receive the most individuals, particularly in the Lower Mainland area outlying Vancouver, on southern Vancouver Island, and on the Sunshine Coast. The range of Red-eared Sliders in BC overlaps that of the Threatened Pacific Coast population of Western Painted Turtle (Chrysemys picta bellii). Herein we report on a survey for both species, noting presence, assessed population sizes, and nesting activity. Across 19 sites in the south coast occupied by both turtle species, we found the median abundance of Red-eared Sliders to be 2.5 times larger than that of Western Painted Turtles (Mann–Whitney U = 104, n1 = n2 = 19, Z-Score = −2.2188, P = 0.02642, two-tailed). There had been no evidence of Red-eared Sliders successfully hatching in the wild in BC until our study. We observed complete development, with 19 neonates from three different nesting sites between 2015 and 2017. Thus, Red-eared Slider is indeed established and able to breed in BC and thus competition and disease introduction from the species likely contributes to the decline of the Pacific Coast population of Western Painted Turtle, particularly at sites with low painted turtle numbers. The scale and mechanisms of impact requires further investigation.

Microgravity effect of inter-seismic crustal dilatation

Changes in the density of the shallow crust has been previously related to co-seismic strain release during earthquakes, however, the influence of inter-seismic deformation on crustal density variations is poorly understood. Here we present gravity observations from the iGrav superconducting gravimeter in southern Vancouver Island, British Columbia, Canada which reveal a substantial gravity increase between July 2012 and April 2015. We identify a negative correlation between this gravity increase and crustal dilatation strain derived from horizontal GPS velocities. The overall increasing gravity trend is caused by the gravity increase during and immediately before and after episodic tremor and slip events, which is partially compensated by gravity decrease occurring between the events. We conclude that the observed gravity increase results from a density increase due to crustal compression and that this is mostly a result of inter-seismic strain accumulation during the subduction of the Juan de Fuca plate beneath the North American plate.

Structural and Metamorphic History of the Leech River Shear Zone, Vancouver Island, British Columbia

AbstractThe Leech River Shear Zone (LRSZ) on southern Vancouver Island separates the metasedimentary schists of the Leech River Complex (LRC) from the accreted oceanic plateau of the Siletz‐Crescent terrane. The juxtaposition of these rock units suggests a possible origin as a subduction plate boundary but tectonic context of the LRSZ has yet to be fully established. We present field, microstructural, petrological, and geochronological observations that constrain the structural and metamorphic history of LRSZ. The mylonite zone of the LRSZ straddles the lithologic contact between the schists of the LRC and basalts of the Siletz‐Crescent terrane. Foliation orientations, a steeply plunging stretching lineation, and kinematic indicators all suggest reverse‐sinistral motion. Compositions of garnet in the schist and amphibole in the metabasalt record synkinematic growth at temperature and pressure conditions of 550°C–570°C and 450–490 MPa. These metamorphic conditions require elevated geotherms that are consistent with plate models that position the Kula‐Farallon Ridge and Yellowstone Hotspot in the region in the Eocene (∼50 Ma). Detrital zircon U‐Pb age distributions for the Leech River Schist have Paleocene maximum depositional ages and are similar to the Upper Nanaimo Group that unconformably overlies the Wrangellia terrane. Our ages support early Paleocene deposition of the schist in a subduction trench/slope environment followed by underthrusting and underplating. These results establish the exhumed mylonite zone of the LRSZ as a paleo‐plate interface that was active during Eocene subduction.

Eocene Terrane Accretion in Northern Cascadia Recorded by Brittle Left‐Lateral Slip on the San Juan Fault

AbstractThe San Juan fault (SJF), on southern Vancouver Island, Canada, juxtaposes the oceanic Wrangellia and Pacific Rim terranes in the northern Cascadia forearc, and has been suggested to play a role in multiple Mesozoic‐Cenozoic terrane accretion events. However, direct observations of the SJF's kinematics have not been documented and its exact role in accommodating strain arising from terrane accretion is unknown. To test if, how, and when the SJF accommodated accretion‐related strain, we use geologic mapping, kinematic inversion of fault‐plane slickenlines, and dating of marine sediments to constrain the timing and direction of brittle slip of the SJF. P‐ and T‐axes from kinematic inversions indicate predominantly left‐lateral slip. Left‐lateral brittle faulting cross‐cuts ∼51 Ma magmatic intrusions and foliation, providing a maximum age of brittle deformation. The fault zone is non‐conformably overlain by a &gt;300 m‐thick sequence of clastic marine shelf and slope sediments that are not left‐laterally offset. A strontium isotope age of foraminifers helps constrain the depositional age of the sediments to late Eocene–early Oligocene, bracketing left‐lateral slip to the Eocene. Eocene left‐lateral slip is temporally and kinematically consistent with regional southwest‐northeast compression during accretion of the Siletzia ocean island plateau, suggesting brittle slip on the SJF accommodated strain resulting from the accretion of this terrane. This result does not support hypotheses that brittle slip along the SJF directly accommodated earlier accretion of the Pacific Rim terrane to Wrangellia, instead it offsets the older accretionary boundary between these two terranes.

Large size (>100-μm) microplastics are not biomagnifying in coastal marine food webs of British Columbia, Canada.

Microplastics (MPs) contamination in marine environments is of increasing concern, as plastic particles are globally ubiquitous across ecosystems. A large variety of aquatic taxa ingest MPs, but the extent to which animals accumulate and transfer MPs through food webs is largely unknown. In this study, we quantified MP uptake in bivalves, crabs, echinoderms, and fish feeding at different trophic levels at three sites on southern Vancouver Island. We paired stable-isotope food web analysis with MP concentrations in digestive tracts across all trophic levels and in fish livers. We then used Bayesian generalized linear mixed models to explore whether bioaccumulation and biomagnification were occurring. Our results showed that MPs (100-5000 μm along their longest dimension) are not biomagnifying in marine coastal food webs, with no correlation between the digestive tract or fish liver MP concentrations and trophic position of the various species. Ecological traits did, however, affect microplastic accumulation in digestive tracts, with suspension feeder and smaller-bodied planktivorous fish ingesting more MPs by body weight. Trophic transfer occurred between prey and predator for rockfish, but higher concentrations in full stomachs compared with empty ones suggested rapid excretion of ingested MPs. Collectively, our findings suggested the movement of MP through marine food webs is facilitated by species-specific mechanisms, with contamination susceptibility a function of species biology, not trophic position. Furthermore, the statistical methods we employ, including machine learning for classifying unknown particles and a probabilistic way to account for background contamination, are universally applicable to the study of microplastics. Our findings advance understanding of how MPs enter and move through aquatic food webs, suggesting that lower-trophic-level animals are more at risk of ingesting >100-μm MPs, relative to higher-trophic-level animals. Our work also highlights the need to advance the study of <100-μm MPs, which are still poorly understood and may need to be considered separately in ecological risk assessments.

Critical food guidance from the slow food movement: The relationship barometer

The Slow Food movement embeds food guidance that encourages interaction with local food production and appreciation of local cuisine. It advocates critical thinking and actions that support the preservation of traditional food practices, as well as environmental considerations around food harvesting and processing. We begin by contextually situating Slow Food as a movement and a change agent. We then introduce a critical guidance tool called the Slow Food Relationship Barometer, developed by Fader and Mesmain from their experience in southern Vancouver Island, British Columbia. This tool is meant for use by advocacy groups and policy makers rather than individuals. It is based on the view that identifying and assessing the multiple relationships intrinsic to a local food product—from origins to the table—can reveal pathways toward its improved sustainability. We illustrate how the Relationship Barometer can be applied to the case of wild and farmed salmon, which also underlies the Slow Fish movement.

Incremental gains in response time with varying base location types for drone-delivered automated external defibrillators

IntroductionDrone-delivered automated external defibrillators (AEDs) may reduce delays to defibrillation for out-of-hospital cardiac arrests (OHCAs). We sought to determine how integration of drones and selection of drone bases between emergency service stations (i.e., paramedic, fire, police) would affect 9-1-1 call-to-arrival intervals. MethodsWe identified all treated OHCAs in southern Vancouver Island, British Columbia, Canada from Jan. 2014 to Dec. 2020. We developed mathematical models to select 1–5 optimal drone base locations from each of: paramedic stations, fire stations, police stations, or an unrestricted grid-based set of points to minimize drone travel time to OHCAs. We evaluated models on the estimated first response interval assuming that drones were integrated with existing OHCA response. We compared median response intervals with historical response, as well as across drone base locations. ResultsA total of 1610 OHCAs were included in the study with a historical median response interval of 6.4 minutes (IQR 5.0–8.6). All drone-integrated response systems significantly reduced the median response interval to 4.2–5.4 minutes (all P < 0.001), with grid-based stations using 5 drones resulting in the lowest response interval (4.2 minutes). Median response times between drone base location types differed by 6–16 seconds, all comparisons of which were statistically significant (all P < 0.02). ConclusionIntegrating drone-delivered AEDs into OHCA response may reduce first response intervals, even with a small quantity of drones. Implementing drone response with only one emergency service resulted in similar response metrics regardless of the emergency service hosting the drone base and was competitive with unrestricted drone base locations.

Abstract 9873: Comparing Base Locations for Drone-Delivered Defibrillators

Introduction: Drone-delivered defibrillators may improve response for out-of-hospital cardiac arrest (OHCA). Prior studies have assumed that drones may be stationed at any police, fire, or paramedic station; however, cross-service implementation may not be logistically feasible. We sought to compare estimated response times by drone base location type. Methods: We included OHCAs (Jan. 2014 to Dec. 2020) in southern Vancouver Island, British Columbia, Canada where OHCA response includes fire and paramedic services. We created four models with candidate drone base locations at: police stations, fire stations, paramedic stations, and on a grid with 1 km sides as an optimistic model. We used mathematical optimization to select 1-5 drone bases for each model. Assuming a drone system had been in place during the study period and accounting for drone availability, we estimated 9-1-1 call-to-defibrillator intervals (measured to either drone, paramedic, or fire arrival) and calculated the proportion of OHCAs where a drone would arrive prior to fire and paramedic for each model. Median response times were compared to historical response using one-sided sign tests. Results: We included 1,610 OHCAs with a median historical response time of 6.4 mins (IQR 5.0-8.6). We identified 21 police stations, 59 fire stations, 21 paramedic stations, and 7,008 grid locations in the study area. Median 9-1-1 call-to-defibrillator intervals ranged from 4.3-5.3 mins for police, 4.3-5.3 mins for fire, 4.5-5.4 mins for paramedic, and 4.2-5.4 mins for grid locations (all P&lt;0.001). Drones arrived prior to fire and paramedics in 36.6-65.4% of cases for police, 38.1-66.2% for fire, 37.3-63.2% for paramedic, and 35.7-66.8% for grid locations. Conclusion: Locating drone bases at different types of emergency service stations significantly decreases 9-1-1 call-to-defibrillator intervals, while resulting in similar response intervals to those achieved using optimistic grid-optimal locations.

The Spatial Relationship Between Contemporaneous Tremor Detections in Relatively Low‐ and High‐Frequency Bands

AbstractAlthough tremor is believed to consist of myriad low‐frequency earthquakes (LFEs), it also contains longer‐period signals of unknown origin. We investigate the source of some of the longer‐period signals by locating tremor windows independently in relatively high‐frequency (“HF”, 1.25–6.5 Hz, containing typical LFEs) and low‐frequency (“LF”, 0.5–1.25 Hz) bands. We hypothesize that if tremor consists entirely of LFEs, such that the lower‐frequency signals come from the non‐uniform timing of higher‐frequency (∼2 Hz) LFEs, then contemporaneous LF and HF signals should be nearly co‐located. Here we search for a systematic offset between the locations of contemporaneous LF and HF detections during rapid tremor migrations (RTMs). This first requires correcting for apparent offsets in location that arise simply from filtering in different passbands. To guard against possible errors in our empirical filtering effect corrections, we focus on a region of the subduction interface beneath southern Vancouver Island that hosts migrations propagating in nearly opposing directions. We find that the LF energy appears to occur roughly 500 m farther behind the propagating fronts of RTMs than the HF energy, whether those fronts propagate to the ENE or to the WSW. This separation is small compared to the location error of individual LF detections, but the result seems robust owing to the large number of detections. If this result stands, it suggests that tremor consists of more than just a collection of LFEs, with longer‐period energy being generated farther behind the migrating fronts of RTMs, where slip speeds are presumably lower.

The Efficacy of Management Measures to Reduce Vessel Noise in Critical Habitat of Southern Resident Killer Whales in the Salish Sea

The inland waters around southern Vancouver Island and northern Washington State, known as the Salish Sea, host critical habitat for endangered southern resident killer whales (SRKW). This is, however, a highly traversed area, with approaches to industrial ports and coastal cities, international shipping lanes, ferry routes, and considerable recreational vessel traffic. Vessel noise is a key threat to SRKW prosperity, and so conservation measures directed to mitigate its effects have been explored annually since 2017. Here, we describe trials undertaken in 2020, which included spatially limited slowdown zones, exclusion areas as Interim whale Sanctuary Zones (ISZs), and a lateral displacement of tug transits to increase the distance between their route and SRKW foraging areas. To assess each of the measures we first considered the level of mariner participation using data from the Automated Identification Systems (AIS), mandatory for commercial vessels. Knowing this, the changes in soundscape were examined, focused on impacts on broadband (10 Hz to 100 kHz) ambient noise and the frequencies used by SRKW for communication (500 Hz to 15 kHz) and echolocation (15 to 100 kHz). A control period of two-months prior to trial initiation was used to quantify the changes. High levels (&amp;gt; 80%) of compliance were found for each measure, except ISZs, where observance was low. Median reduction in speeds ranged from 0.2–3.5 knots. Resulting sound reductions were most notable in the lower frequencies, although reductions were also recorded in SRKW pertinent ranges. Tug displacement also reduced ambient noise in these frequencies, despite making up a small portion of the overall traffic. The management trials were effective in reducing potential impacts singularly and in concert. Greater awareness and stakeholder engagement may increase compliance and, therefore, the efficacy of measures in the future.

Freshwater jellyfish in northern temperate lakes: Craspedacusta sowerbii in British Columbia, Canada

Freshwater jellyfish species of the genusCraspedacustapurportedly originated from the Yangtze River catchment area, China, and have now been observed on all continents except Antarctica. Sightings ofC. sowerbiiin the Pacific regions of Canada were compiled to document some of the northernmost records of this species in the Americas. Species identification has been difficult in the past. Therefore, field collection of specimens was carried out on southern Vancouver Island. The morphology was described macro- and microscopically as well as molecularly using mitochondrial and nuclear markers. Collected hydromedusae from British Columbia (BC) did not deviate morphologically fromC. sowerbiispecimens from other continents, but molecular analyses support the idea of 2 main widely distributed lineages hidden under similar morphological features (i.e. a species complex). Through a community science approach, an understanding of the extent ofC. sowerbiidistribution in western and southern BC (present in 24 lakes from as early as 1990) has been established. Results showed that the number of sightings increased considerably in the period after 2010. Recent increases in sightings ofC. sowerbiiin BC and worldwide could be indicative of a climate warming-related range extension or growing public awareness and/or increased observational efforts. Even after more than 120 yr ofCraspedacustaresearch, much about their biology and ecology remains unknown, which motivated us to compile a list of knowledge gaps based on an extensive literature survey.