Nearshore Habitat Studies

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There are several key projects in this category and several others are currently under consideration.

1. Estuarine and Coastal Restoration in the Salish Sea

Team: Nikki Wright, Executive Director, SeaChange Marine Conservation Society, Leanna Boyer, B.Sc., M.A. Jamie Smith, WCB SCUBA diver, photographer, videographer, Justin Bland, WCB SCUBA diver, Sarah Verstegen, WCB SCUBA diver, dive tender, SeaChange Operations Manager, Keith Erickson, R.P. Bio, Galiano Conservancy Association, Anuradha Rao, B.A.Sc., M.Sc., R.P. Bio., David F. Polster, B.Sc., M.Sc., R.P. Bio. , Doug Biffard

Objective:

The purpose of this project is to continue to restore estuarine and coastal ecosystem resiliency and health in the Salish Sea for all species of salmonids and the marine food web upon which they depend.

Background:

This project is part of the bottom-up approach to improving food webs and nearshore habitats for juvenile salmon within the context of the Salish Sea Marine Survival Project. Eighteen sites are presently monitored for transplant density and coverage. For 2015-2017, the goal was to continue and expand this work. Three new components were added. The first was to add monitoring devices within their transplant sites to understand such parameters as annual sediment flows, water velocities, light availability and temperature. The second was to restore nearshore riparian vegetation in areas identified as critical nearshore marine habitats for juvenile salmon. The third was to begin research through a local university or college on mitigation methods that can be utilized to increase eelgrass growth in former log boom areas on a small landscape scale.

Sites identified for the above works included the Cowichan Estuary and Genoa Bay, Squamish River Estuary, Salt Spring Island (Burgoyne Bay), and Burrard and Sechelt Inlets.

Eelgrass and riparian vegetation were to be mapped in areas considered critical nearshore and coastal nursery habitats for salmon in the southern and central areas of the Salish Sea. Restoration of eelgrass (Zostera marina) was to be continued using a well- established science based methodology. Riparian shoreline areas were to be restored where feasible.  Environmental indicators used to gauge the project’s success include the number of potential restoration sites located through inventories, area increase in eelgrass habitat as measured in meters square, measurement of transplanted eelgrass shoot densities and metres square of nearshore riparian areas restored.

Activities in all locations wre to be conducted in consultation with First Nations. Where possible, training in habitat mapping and restoration will occur in these communities to increase capacity to conserve nearshore marine habitats. Presentations, field tours and school programs focused on the high value of nearshore salmonid habitats will continue to be an important stewardship component of this project.

Summary of key results:

  • A total of 9,238m² of eelgrass habitat was restored during 2015-6. Site locations included Sechelt , Burrard and Saanich Inlets, Cowichan Bay (Genoa Bay), Maple Bay, Squamish, Mill Bay, Pender and Mayne Islands, and three sites within BC Parks (Montague Harbour, Wallace and Gambier Islands).
  • Four marine riparian areas (Tod, Burrard and Sechelt Inlets and Mayne Island) were re-vegetated to increase salmon feeding grounds and forage fish spawning areas on the nearshore.
  • HOBO units and sediment traps were installed in Genoa and Mill Bays and Squamish estuary; sediment samples were collected from 23 transplant sites.
  • 50km² was mapped in Boundary Bay and an Eelgrass Report was produced for the Municipality of Oak Bay after eelgrass habitat was mapped surrounding the township.
  • A total of 170 community volunteers of all ages participated in restoration activities.
  • Over 2500 people heard about the value of eelgrass habitats to salmon survival during several conferences, presentations and public tours. Educational brochures were produced in partnership with Parks Canada.
  • Videos of all “before and after transplant” sites are available for viewing.
  • SeaChange is participating in the newly rejuvenated Burrard Inlet Water Quality Working Committee as they feel they can contribute to improving water quality for salmon through restoration of eelgrass habitats and water quality monitoring
  • Completed sediment composition and chemistry analyses and reports from sediment samples by Ecotox Lab, Simon Fraser University – Drs. Vicki Marlatt and Leah Bendall, supervisors. To be posted on the SGDC website
  • Completed monitoring data for all 23 eelgrass transplant sites (including water temperature, velocity, sediment loads, and light attenuation).
  • Created synthesis report for all conservation work from 2013-2017 inclusive, to be posted December, 2017 on the Strait of Georgia Data Centre web site. Received by December, 2017.
  • Research of sediments within the transplant sites continued with the University of British Columbia’s with Dr. Mary O’Conner and the University of Simon Fraser with Dr. Sheryl Bisgrove. Subjects of research: Effects of non-point pollution on eelgrass food webs in Boundary Bay, and effects of multiple stressors, including log storage, continuing the work already supervised by Dr. Leah Bendell at SFU.

The movie below shows a juvenile salmon’s view of a kelp bed in Cowichan Bay.

2.     Mapping, Protection and Enhancement of Forage Fish spawning habitat

Team: Ramona deGraaf (BMS), BC Shore Spawners Alliance & volunteers

Objectives:

  1. Determine the spatial extent of spawning habitat and suitable habitats for surf smelt and Pacific sand lance in the Salish Sea
  2. Protection of forage fish resources (secondary capacity) in the Salish Sea
  3. Development of operational statements and best management practices for forage fish spawning/rearing habitats and marine riparian habitats for local government and stakeholders.

Background:

The forage fish specialists and communities working with the BC Shore Spawners Alliance (BCSSA) are interested in protecting the health of marine ecosystems and the productivity of forage fish to benefit marine populations.

Herring, Pacific sandlance, and surf smelt are the most abundant marine forage fishes in the Strait of Georgia/Puget Sound. Pacific sandlance may represent a greater trophic biomass for marine species than herring (D. Penttila, personal communication).  Forage fish represent a valued ecosystem component essential to marine food chains, connecting zooplankton to a host of secondary predators.

Protecting critical beach spawning and rearing habitats of surf smelt and Pacific sand lance is necessary to sustain forage fish biomass and the predator species reliant on them.

Sandlance and surf smelt require near-shore habitats for their survival. Departments approving development permits lack up-to-date information and are largely unaware of the impact of shoreline development on the survival of forage fish. Protecting beach spawning habitat for Pacific sandlance and surf smelt has resulted in strict shoreline protection policies in Washington State. Yet in British Columbia little has been done to inform land-use policies to protect these crucial beach habitats. The majority of important departments and biologists in agencies know very little about intertidal beach spawning forage fishes. Educating agencies responsible for coastal land-use planning in British Columbia about these critical fish species is imperative. Already, vast areas of shoreline in southern British Columbia have been altered and historical spawning grounds lost.

The work of the BC Shore Spawners Alliance (BCSSA) is a result of the growing realization that throughout the Strait of Georgia and in other rapidly developing BC coastal communities, intertidal forage fish spawning habitat was being degraded or lost. Stewardship groups such as the Friends of Semiahmoo Bay Society, Wreck Beach Preservation Society and the West Vancouver Shoreline Preservation Society and Stanley Park Forage Fish Friends are actively working on forage fish surveys, beach restoration and enhancement, and surf smelt recreational fishing issues.

Sea Watch society’s project focusses on the declining habitat quality for two key forage fish species, surf smelt and Pacific sand lance, and coastal marine rearing habitat for juvenile salmon.

These projects seek to advance the goal of the SSMSP to support the recovery of wild salmon and sustainable fisheries by identifying major factors affecting the survival of juvenile salmon in the Salish Sea by undertaking research activities that protect and restore critical salmon habitats.  Critical salmon habitats include those habitats that support spawning and rearing of prey species vital to salmon recruitment as defined by WA State ecosystem-based management principles for forage fish management and the BC Wild Salmon Policy.

Along shoreline units that have been heavily degraded, restoration/enhancement recommendations will be made to aid habitat restoration projects to recover and protect declining Strait of Georgia surf smelt stocks, protect Pacific sand lance spawning habitats, and enhance juvenile salmon coastal rearing habitats.  The maps and data will also assist in allocation of oil spill remediation resources.   Such a project is vitally important to protect and conserve critical marine fish habitats within the project locations.

Status:

Spawning Surveys by Sea Watch and Community Monitoring Efforts have been carried out for over 10 years. In total, approximately 280 beaches monitored. Of these, 50 are positive for Pacific Sand lance, 52 for Surf smelt, and 4 mixed Surf smelt/Pacific sand lance.  Over 30km of spawning beds have been monitored.  In addition, studies have been underway to elucidate the Surf smelt spawning stock structure- both in the summer, winter and year-round.  Strait of Georgia Surf smelt spawning stock structure is similar to that in Puget Sound with summer, fall/winter and year-round spawning.  Work continues to define the geographic boundaries and/or overlap of these stocks within the Strait.

With respect to the Forage Fish Spawning Habitat Suitability Model, 12 Islands Trust islands have been completed and project is ongoing with 3-4 islands being undertaken for 2017-2018.  The Lower Mainland project consists of Howe Sound; English Bay/Burrard Inlet; and Delta/Surrey.  The Howe Sound project was delayed and will recommence in 2017.  The other components of the Lower Mainland project have been completed.

Working with partners in Puget Sound, a beach condition model has been completed.  The matric allows for the consistent assessment and scoring of marine shorlines as to their current condition (health) of marine shorelines which are important as spawning/rearing habitats for Surf smelt, Pacific sand lance and neustonic insect prey for juvenile salmonids.  This model has been applied to English Bay/Burrard Inlet.  A technical report and potential journal publication of the model is being pursued with project partners.

Other areas of progress include the development of the English Bay/Burrard Inlet Surf smelt Habitat Technical Review and Restoration Plan. This Plan will provide science-based recommendations to

  • Protect critical forage fish resources
  • Prioritize marine shoreline habitat Prioritize restoration areas
  • Model the impact of sea level rise on setting conservation targets
  • Prioritize enhancement of marine riparian vegetation

Further Case Studies will include Denman Island and the Capital Regional District.

3. Spatial temporal distribution of Nereocystis luetkeana (bull kelp) and use by juvenile salmonids in the Salish Sea

Team: Maycira Costa, UVic; Nikki Wright, SeaChange Marine Conservation Society; Leanna Boyer, SeaChange Marine Conservation Society; Sarah Schroeder, Graduate student, UVic; and various collaborators

Objectives:

The objectives of the expanded full project for 2016-2017 are: (1) to define the surface extent of bull kelp beds by using satellite imagery (present and historical) associated with sea-kayak surveys for several regions of the Gulf Islands (Salt Spring, Saturna, North and South Pender, and Mayne), and Comox and Cowichan estuaries, in collaboration with several environmental stewardship community organizations and First Nation groups. (2) To initiate a robust study on the use of kelp habitat by juvenile salmon in the Salish Sea.

Background:

Kelp, specifically Nereocystis luekeana (bull kelp), form extensive forests in rocky habitats along the subtidal zone of the coast of British Columbia. Kelp forests provide important habitat for juvenile salmon attracting their preferred food and providing protection from predators. Of particular interest to the Salish Sea Marine Survival Project (SSMSP), kelp habitats have been shown to provide optimal feeding and refuge conditions for Chinook and Coho in the Strait of Juan de Fuca (Shaffer, 2003). Declines of Cowichan juvenile Chinook are largely attributed to their high mortality within the first four months in the southern Gulf Islands. One method of improving Chinook production is to find a way of improving kelp production (Beamish et al. 2011). However, there is a dearth of information of the existing populations and distribution of these kelp habitats in the southern Gulf Islands. As such, the need for kelp bed distribution for the Salish Sea was one of the main data gaps identified at the Salmon Habitat meeting in July 2014. Other research initiatives related to this proposal are the successful Kelp Mapping project using Satellite Technology and the Estuarine and Coastal Restoration in the Salish Sea.

At present, the majority of kelp mapping is conducted manually via transects and aerial photography. Though effective, the strategy is labour-intensive, requires large time investment, and is limited by the areas surveyed. During 2015 Costa et al. carried out a successful short pilot project (3 months) to evaluate and define methodologies to use satellite imagery (present and historical) to map the aerial extent of kelp beds on BC coastal waters. The 2015 pilot project was completed and the full project goal for 2016-2017 was to apply the developed methods to the BC coastal waters and work together with local communities and First Nations in collaboration with SeaChange to improve data collection and the use of satellite imagery.

Status:

Nereocystis leutkeana, or Bull kelp provides important ecological functions as a source of nutrients, refuge and habitat for many organisms including juvenile salmon and invertebrates. It is the dominant canopy forming macroaglae in the interior Salish Sea from the Gulf Islands to the strait of Georgia.  Monitoring the spatial distribution of kelp and the extent to which juvenile salmon use kelp beds is an important element of assessing ecosystem health. This report provides the preliminary results of (1) the analysis of the temporal high-resolution satellite imagery and (2) the field survey of kelp habitats and juvenile Chinook and Coho salmon in the Salish Sea.

Part 1: Remote sensing of bull kelp (Nereocystis luetkeana) and detection of temporal changes in the Salish Sea using high resolution satellite imagery:

Results of the methods developed for the detection of bull kelp in high-resolution satellite images show that the technique has good accuracy when image collection conditions are suitable .  When tides are low and kelp beds are dense or mostly on the surface, kelp can be detected with high accuracy. However, conditions in historical imagery including tide, date and surface conditions are not optimized for remote sensing of kelp and thus kelp detected in these images does not necessarily represent the true maximum extent of kelp present in that year.  For this reason, temporal analysis considers kelp presence or absence in defined regions rather than kelp area. Preliminary results in a subset of the study area show that while bull kelp area varies from year to year it does not show a temporal increasing or decreasing trend. Further refinements to the methodology for analyzing temporal data are being explored to improve the ability to validate historical classifications and define metrics for measuring the reliability of results due to inherent limitations caused by image conditions.

Part 2: Bull Kelp Beds as Juvenile Salmon Habitat:

Field surveys conducted in summer 2017 consisting of snorkel transects and stationary underwater video. This data was analyzed in fall and winter 2017-2018. Each of the four sites contained both kelp and no kelp habitat however, the kelp habitat did not form full beds until mid-June. Snorkel transects were conducted on the inside edge, middle of kelp beds and outside edge of kelp beds. Of the fish species recorded through snorkel transects from April to August 2017, 12% were juvenile salmon.  Peak salmon counts were recorded in mid-May, before kelp canopy was present .  There were significantly more juvenile salmon counted in kelp habitats compared to no kelp habitat. However, this difference is likely due to the transects on the inside edge of kelp habitat .  The inner kelp transects had significantly more juvenile salmon prior to kelp growth and with kelp canopy present. This indicates that characteristics inherent to this inner rocky nearshore habitat may be important to juvenile salmon.

Outcomes:

  • The results of the kelp mapping via satellite will be used to understand how changes in nearshore habitat may be affecting juvenile salmon survival. The results from analysis of juvenile salmon abundance in kelp and non-kelp habitat help to confirm the importance of kelp beds to the marine survival of juvenile salmon.
  • Satellite imagery is effective for mapping kelp distribution. The kelp distribution maps extend from 2004 to 2017. Gaps in the availability and quality of imagery data limit the ability to extend mapping to a longer-term data set as kelp beds in the region are small relative to the resolution of older images.
  • The salmon use of kelp beds study indicated a mismatch between the time salmon are entering the marine environment in April and May and the growth of kelp in Cowichan bay which became apparent in June. In areas further from Cowichan bay kelp was present in early April. The data suggest a preference for nearshore rocky intertidal environment on the inside edge of kelp beds.

Lessons Learned:

  • In order to create accurate kelp maps from satellite imagery the images must meet a certain criteria for tide level, sun glint, and sensor angle.
  • Kelp bed classifications which show kelp is not present must be weighted by the conditions of data collection such as the tide level and flow direction, the satellite sensor angle and sun glint.
  • The results of the kelp mapping show that satellites are an effective and accurate method for mapping kelp. When images do not have the right conditions, results may misrepresent the true distribution. Results will be available as a long-term presence and absence to account for issues in imagery.
  • Mapping of the kelp distribution in the Salish Sea should be continued and expanded. Reports of large declines in the Central Strait of Georgia should be investigated.  Due to the natural variability in Nereocystis populations a continuous long term data set will best capture trends in spatial extent and distribution.
  • The results of the relative abundance of salmon in kelp versus non-kelp habitats indicate that while salmon do appear to utilize kelp associated habitat more than non-kelp, the conditions in the study area were not ideal for comparison due to the delay in kelp growth and the size of the beds. Choosing a study area where kelp beds grow earlier in the season may produce results that are more representative of salmon behaviour.

4. Evaluating seagrasses as habitats for juvenile salmon

Team: Laura Kennedy, MSc student, UVic, Dr. Rana El-Sabaawi, UVic, Dr. Francis Juanes, UVic.

Objectives:

To determine the impact of eelgrass density on invertebrate communities, and to determine the importance of prey originating from eelgrass ecosystems to juvenile salmon diets.

Background:

The primary goal of the SSMSP is to identify the most significant factors affecting the marine survival of juvenile salmon in the Salish Sea marine environment. Currently, they do not understand how juvenile salmon in the Salish Sea use nearshore environments in their early marine life, and how habitat complexity, degradation, or restoration of nearshore environments affects the availability of important juvenile salmon habitats. Shore development and climate change have led to the loss and degradation of nearshore ecosystems including seagrasses, which have been shown to be critical for juvenile salmon in many coastal ecosystems. The goal of this study is to assess the value of seagrass ecosystems as foraging grounds for juvenile salmon, and to quantify the effects of seagrass damage and restoration on the availability of high quality salmon diets.

Status:

Ms. Kennedy’s project had two objectives: 1. to compare the availability of invertebrates along a gradient of seagrass health, and 2. to assess whether seagrass meadows provide prey for juvenile salmon. A pilot in the Cowichan Bay estuary showed that the seagrass habitats in the bay were not suitable objective 1 (no discernable seagrass gradients, and most meadows only accessible using snorkeling surveys). As a result, her sampling location was moved to the Comox estuary, which has a high abundance of accessible seagrass habitat containing a gradient of dense to sparse beds.

Laura has now successfully completed her MSc at the University of Victoria. Her study showed that eelgrass habitat supported a variety of prey items for juvenile salmon. Prey abundances increased with increasing eelgrass abundance, but did not change in composition across eelgrass density. Juvenile Chum and Chinook salmon diet was dominated by approximately 80% of benthic diet items, all found in eelgrass habitat, supporting the hypothesis that eelgrass habitat can provide foraging grounds for juvenile salmon. Juvenile Chum salmon isotope signatures closely reflected those of eelgrass invertebrates, indicating juvenile Chum salmon utilized eelgrass invertebrates from the Comox Estuary, BC.

Lessons learned include:

  • Eelgrass habitat may provide important foraging grounds for juvenile salmon. Higher-density eelgrass habitat provides increased prey abundance, but even sparse habitat may be an important habitat feature, as it may provide a unique invertebrate community targeted by juvenile salmon.
  • Eelgrass habitat should be protected in near-shore habitats, especially those frequented by juvenile salmon, or close to salmon-bearing streams. Restoration practices should continue, with increased monitoring of the status of natural and restored to better understand how the success of these habitats can influence juvenile salmon feeding.

This project reduces uncertainty around the role of near-shore habitat for juvenile salmon. Specifically, it indicates that the conservation of eelgrass habitat may protect foraging opportunities for juvenile Pacific salmon during a vulnerable life history stage, when growth is critical.

5. Diversity and structure of coastal eelgrass communities and their importance for maintaining juvenile Pacific salmon

Team: Dr. Josie Iacarella, post-doc, UVic, and Dr. Julia Baum, UVic.

Background:

On the coast of British Columbia, both eelgrass meadows and Pacific salmon species are declining, yet eelgrass community dynamics and reliance of juvenile salmon on these communities are poorly understood. They will assemble the first large-scale dataset from monitoring efforts of coastal BC organizations in order to assess eelgrass community diversity and structure across environmental and human disturbance gradients (including boating, fishing, and non-native species). The final outcome of this research will be an index of eelgrass ecosystem health for all monitored meadows based on their ability to provide ecosystem services including provision of habitat for juveniles of salmon and other commercially-important fishes.

Status:

Since beginning her Postdoctoral Fellowship in November, 2016, Josie assembled a working group of 20+ individuals who are involved in surveying fishes across the coast of BC. Partner organizations and groups include: Nootka Sound Watershed Society, Parks Canada, West Coast Aquatic, Uu-a-thluk, Raincoast Conservation Foundation, Hakai Institute, Project Watershed Society, Nile Creek Enhancement Society, UBC labs, and the UVic Baum lab. The working group has been framed within a larger network that is forming, Seagrass BC, led by Hakai Institute and SeaChange Marine Conservation Society.

In February, they held a workshop for working group partners to discuss research questions and field methods. They decided to focus on 2 projects: (1) an assessment of juvenile salmon use of eelgrass vs. non-eelgrass habitats throughout the outmigration period, paired with gut content analysis and invertebrate prey surveys at the paired habitat sites, and (2) an assessment of fish diversity in eelgrass habitats across coastal gradients of human disturbance.

The juvenile salmon project was conducted in 5 regions (Tahsis Inlet, Bedwell Estuary, Fraser Estuary, Bowser Lagoons, and Koeye Estuary). The surveys began end of April/early May and continued through the summer, generally on a biweekly basis. They conducted beach or purse seines (depending on the region), invertebrate dip net sweeps, and collected some salmon juveniles (species and amount depending on region). They will use these data to compare abundances of juvenile salmon and their invertebrate prey in eelgrass vs. non-eelgrass (generally sandy or rocky) habitats; gut content analysis will be used to determine if the prey collected in each habitat matches what the juvenile salmon are consuming.

The fish diversity project was conducted from mid-June through July 2016 in 12 regions spanning the mainland from the Fraser Estuary – Calvert Island – Skeena Estuary, and covering a large spatial extent of Vancouver Island. This project involves a one-time survey of approximately 6-12 eelgrass sites per region. They sampled beach seining sites and characterized the eelgrass meadows (e.g. shoot density, percent cover, epiphyte load). Following the surveys, Josie and an Honour’s student at UVic gathered functional trait information on the fishes that are caught (including morphometric analysis), and worked to quantify human disturbance levels at the surveyed sites. Human disturbance includes measures of distance to human-made structures, boating activity levels, and adjacent human population densities; they will also be preparing eelgrass samples to analyze δ15N to determine if they can distinguish anthropogenic nutrient inputs from natural inputs. Josie will also be assessing whether there is evidence of biotic homogenization (reduced beta-diversity) of fish communities among regions with higher levels of human disturbance.

Status:

The Eelgrass Fishes Network was established to facilitate a collaborative effort in surveying eelgrass fishes across the coast of BC in summer 2016. Two workshops were held with 20+ attendees, the first to discuss research questions and survey methods, and the second to review preliminary analyses and plan publications. Network partners collaborated on two projects, (1) the impact of human disturbance on diversity of eelgrass fishes (one-time survey, 9 regions with a total of 89 sites), and (2) the role of eelgrass versus non-eelgrass habitats for juvenile salmon diets and refuge (generally biweekly surveys April – August, 5 regions with two sites each).

In terms of results, there is evidence of decreased species richness and biotic homogenization of eelgrass fishes in highly disturbed regions (sites within Fraser Estuary, Comox Estuary, southern Vancouver Island). Rockfish species, in particular, were an indicator species of low disturbance regions (sites within Clayoquot Sound, Barkley Sound, Central Coast, and Skeena Estuary), whereas threespine stickleback were most associated with high disturbance regions. The higher diversity (within and among sites) of the fish community and the importance of commercially-valuable rockfish species within the community at low disturbance sites exemplifies the need to maintain eelgrass habitat in low disturbance areas.

In addition, the results generally indicate that juvenile salmon use eelgrass habitat more than vegetated habitats, and were most often found to have harpacticoid copepods in their diets – a species associated with eelgrass. The role of eelgrass for juvenile salmon appears to vary by region, potentially in part dependent on the scale of the estuary (e.g. Fraser Estuary versus Bowser Lagoons).

This project contributes to a better understanding of (1) whether coastal human activities are impacting fish communities and (2) the relative contribution of eelgrass habitat to the diet and refuge of juvenile salmon. The results will have implications for the importance of habitat restoration and protection of habitats in low human disturbance areas and/or key outmigration locations.

Josie has taken on a new post-doctoral position so this project was ended approximately 10 months earlier than expected (Jan 2017). However, Josie intends on completing two publication based on the results to date.

6. Remote Sensing Methodology to examine the relationships between eelgrass distribution, upland land use and water quality.

Team: Dr. Maycira Costa, UVic and students/technicians.

Objective:

The goal of this research is to use historic aerial photography and contemporary UAV imagery to investigate the long-term trends in eelgrass habitat distribution in the Salish Sea, and to investigate the potential impact of coastal development in the region on eelgrass habitats.

Background:

Nearshore marine habitats are of great ecological and economical importance. Specifically, eelgrass meadows are one of the most productive and sensitive nearshore habitats. Part of their importance is to provide shelter and food to numerous species including Coho and Chinook salmon, and forage fish such as sand lance and herring. These habitats are threatened by human activities. Specifically, in the Salish Sea, as human population continues to grow, eelgrass beds have been documented as decreasing. However, there is a lack of understanding of the relative threats that are causing the decrease of eelgrass beds in this region. Current mapping efforts are underway to identify the occurrence of eelgrass and potential restoration areas

Aerial photography is a valuable tool for monitoring landscape and ecosystem change. Archived air photos may date back as far as the 1920s, providing the longest available time series in remote sensing data with high spatial resolution and tonal detail making it suitable for mapping temporal change in small habitat units such as seagrass meadows. The goal of this project is to quantify the temporal and spatial dynamics of eelgrass habitats and associated adjacency catchment area land use change over time to further understand temporal changes and associated disturbance/environmental forcing. They are analyzing a long time series of aerial photos (1950-2004) and more recent satellite images for defining eelgrass cover change and land use change in the drainage basin at different scales from the Gulf Islands National Park Reserve and adjacent areas.

Results

Eelgrass (Zostera marina) is a critical nearshore marine habitat for juvenile Pacific salmon (Oncorhynchus spp.) as they depart from their natal streams. Given the poor marine survival of Coho (O. kisutch) and Chinook (O. tshawytscha) salmon juveniles in recent decades, it is hypothesized that deteriorating eelgrass habitats could contribute to their low survival. For three small estuaries in the Southern Gulf Islands of British Columbia, changes in eelgrass area coverage and shape index over the period of 1932-2016 were assessed using historic aerial photographs and Unmanned Aerial Vehicle (UAV) imagery. In addition, changes in eelgrass area and shape index were evaluated in relation to landscape-level coastal environmental indicators, namely shoreline activities and alterations and residential housing density.

All three eelgrass meadows showed a deteriorating trend in eelgrass condition; on average, eelgrass area coverage decreases by 41% while meadow complexity as indicated by the shape index increases by 76% (Figure 1). Shoreline activities (boats, docks, log booms, and armouring) and residential housing density increased markedly at all sites over the study period, which are moderately to strongly correlated to eelgrass area coverage and shape index. Changes in these landscape-level indicators over this time period corroborate the observed decline in eelgrass habitat condition, as they suggest an overall deterioration of coastal environmental health in the Salish Sea due to drastically increased use of the coastal zone as well as declines in water quality due to urbanization.

Figure 1. Spatial temporal maps of eelgrass at three different location, Village Bay, Horton Bay and Lyall Harbor.  Example of location were field work was conducted in the spring/summer of 2016; and graphic showing the percentage of eelgrass cover and shape index change from 1932 to 2016.

Outcomes

  • Eelgrass change over time exhibits a downward trend (41%) from 1932-2016. However, due to changing technologies and air photo interpretability, it is likely that the interpretation of the older air photos is slightly overestimating the eelgrass area coverage because of aggregation of different submerged species that does not occur in later years. As such, the downward trend must be interpreted cautiously.
  • However, fragmentation appears to increase over time. For example, in Horton Bay, where a continuous band of eelgrass existed along the north shore of the bay until 2004, and then fragmentation happened after boat docks and significantly increased boat presence are observed.
  • Shoreline activities and housing density increased significantly over time. Many of the correlations between eelgrass metrics and these potential human impacts are very high (r>0.9). This suggests that increasing use of the coastal zone and changing water quality may indeed be playing a role in the declining trend in eelgrass observed. Specifically, the 1970-80’s period is characterized by large increases in housing density and shoreline activity from the earlier period in 1932-1950. Rate of eelgrass loss after 1975 appears to increase as compared to the previous period.

 Lessons Learned

We do have evidence that there has been an overall decline or degradation of eelgrass nursery areas over the period from 1932-2016. However, this trend must be interpreted cautiously due to the quality of historical data.

7. Restoration Research on Kelp Forest Habitats in the Salish Sea

Team: William Heath, Ph.D (Nile Creek Enhancement Society & Project Watershed Society); Sherryl Bisgrove, Ph.D (Simon Fraser University), Braeden Schiltroth (MITACS student SFU

Objectives:

Objectives of this project include the following:

1) Estimate the extent of kelp forest cover/loss in the northern Salish Sea in recent decades and identify sites in need of restoration that would be of benefit to juvenile salmon

2) Identify kelp stocks capable of growing at sites with stressful conditions (high temperature and/or low pH) by correlating sites that have retained kelp with recorded oceanographic conditions available from online databases (e.g. lighthouse SST databases on DFO Pacific website).

3) Compare bull kelp growth and survival, faunal (fish and invertebrate) presence and detailed oceanographic conditions at 5 experimental sites and at a reference site.

4) Examine the effect of density thinning of sea urchins on kelp abundance at a monitoring site.

Longer term objectives:

1) To identify sources of thermal stress-resilient genetic stocks of bull kelp (Nereocystis luetkeana) in the Salish Sea that can be grown in significant quantities to restore historical kelp beds as habitat for refuge and feeding of juvenile salmon.

Background:

The bull kelp, Nereocystis luetkeana (Mertens) Postels et Ruprecht, is an annual brown macroalga that forms canopies or kelp forests. It typically grows along rocky shores in the Pacific Northwest, especially in areas of moderate to high waves or currents, from below the lowest tide level to about 18 m depth (Kruckenberg 1991). Nereocystis is the direct energy source of herbivores and detritivores and their related food webs (Duggins 1988). Bull kelp forests provide critical habitat for food and refuge to a large number of important commercial and recreational fishery species, including salmonids, juvenile surf smelt, rockfish, lingcod, sea urchins and crabs (Leaman 1980, Duggins 1988). Nereocystis is highly productive, growing in size from microscopic to huge (10 m or more in length) in a single season. By fixing carbon dioxide and releasing oxygen, bull kelp can locally reduce oxygen depletion from biological and chemical processes and thus serve as both a carbon sink (Merrill and Gillingham 1991) and a supply of dissolved organic carbon (Eckman and Duggins 1991).

Despite their high growth and reproductive capacity, bull kelp populations have been in steady decline within central Strait of Georgia (northern Salish Sea), including Lambert Channel and Baynes Sound, (Lamb et al. 2011) as well as in other parts of the Salish Sea in recent decades. Although the reasons for the decline are still being elucidated and have resulted in patchy habitat through many parts of the Salish Sea, this phenomenon is seemingly widespread on the Pacific coast of North America. Factors that may have had an influence on the disappearance of bull kelp beds include coastal development, rising ocean temperature, local changes in oceanographic conditions (e.g. salinity, increased turbidity and sedimentation), intensified herbivore grazing, or a combination of these (Steneck et al. 2002).

This project is aimed at restoration research on critical nearshore bull kelp habitats for use by juvenile salmon in the Salish Sea. It builds upon and extends the findings of research funded by the SSMP in 2015 (Heath et al. 2015) which has established: 1) an experimental system for environmental sampling as well as planting and analysis of bull kelp performance in the field; 2) the role of prolonged warm temperatures (>16C) and herbivore grazing in restricting bull kelp survival; and 3) methods for assessing stress-resiliency of bull kelp populations.

2017 objectives were as follows:

  • To conduct a seeded line outplant experiment at Maude Reef grid (site MR; 7m depth; 49.49853 N 124.68104 W) and at deeper sites on the seaward (outer) side of Maude Reef (MO; 10-12 m depth) and Cape Lazo shoal (CLs; 10-12 m depth; 49.69913 N 124.84165 W) in the Strait of Georgia. A reference site is located at Eagle Rock on southern Denman Island (ER or DI; 9-10m; 49.47715o N 124.68375o W).
  • To collect scientific data to provide information on the possible barriers to natural recruitment, critical ecological and environmental interactions and ways to improve outplanting and restoration performance.
  • To collaborate with experts and others to advance this complex marine habitat issue to create opportunities for further research and restoration work. A key step in 2017 is to continue to collaborate with Dr Sherryl Bisgrove of Simon Fraser University (SFU) and graduate student, Braeden Schiltroth, on kelp research that examines stress resiliency of developmental stages. In a second collaboration, tissue samples of kelp from BC locations are provided to Dr. Filipe Alberto of University of Wisconsin – Milwaukee for a coastwide population genetics study of bull kelp from Alaska to northern California.
    Status:Comparison of genetic sample results for population genetics of bull kelp.

    Genetic samples of the F1 generation were taken from Maude Reef site kelp plants of both sources in June and were analyzed separately by the lab of Dr. Filipe Alberto. Tissue samples from natural set bull kelp at Cape Lazo shoal were also submitted for genetic analysis. Preliminary results indicated that the “wild” Cape Lazo kelp profile resembled that of Campbell River kelp. The recent sample from Dodds Narrows near Gabriola Island also followed the profile of previous samples from the north Salish Sea. Results will be presented in more detail when available.

    Ecological services of bull kelp: During dive and boat operations at the experimental sites and at natural kelp beds during sori collection it was often observed that areas in and around the kelp were used by individuals and schools of juvenile salmon, forage fish and resident fish species (e.g. shiner perch, rockfish) and invertebrates (crabs, caprellid amphipods). These observations are important confirmations of the ecological service of kelp beds as refuge and feeding sites for many fish and invertebrate species in the Salish Sea.

    Comparison with the previous years (2014, 2015 and 2016) of observations:

    1. A major difference between environmental conditions observed in 2017 and those in 2014 and 2015 was that temperatures in 2017 were consistently lower during spring (March to June) but rose to high levels (19 to 21 C) starting in late June through August whereas temperatures in June and July 2015 dipped from above to below 15°C for periods of about a week, whereas in 2014 temperatures continued above 15°C and even 18°C for prolonged periods (over 30 days). There appeared to be significant recovery of condition of many plants in 2015 and 2016 in these periods of respite from higher temperatures. However, kelp condition decline resumed in late July and August 2015, likely due to warm temperatures and the influence of epiphytes and epizoans, but remained quite healthy for many plants in 2016 into August and even October at the deeper, outer Maude site.

    Thus kelp condition at Maude Reef sites was better in the summer of 2016 than in 2015 and 2014 (as well as in 2017), resulting in persistence of healthy bull kelp plants into September and October, with significant sori production and release.

    Suggestions for Future Research

    The trend in several recent years (2013 -2015, 2017) of frequent prolonged periods of warm water (>15°C) in spring and/or summer months in areas of the Salish Sea such as Lambert Channel and Baynes Sound is a major challenge, along with heavy sea urchin grazing, to bull kelp restoration research and performance. In their on-going kelp research they propose the following approaches:

  • Comparison of genetic sample results for population genetics of bull kelp. Genetic samples of the F1 generation were taken from Maude Reef site kelp plants of both sources in June and were analyzed separately by the lab of Dr. Filipe Alberto. Tissue samples from natural set bull kelp at Cape Lazo shoal were also submitted for genetic analysis. Preliminary results indicated that the “wild” Cape Lazo kelp profile resembled that of Campbell River kelp. The recent sample from Dodds Narrows near Gabriola Island also followed the profile of previous samples from the north Salish Sea. Results will be presented in more detail when available.

    Ecological services of bull kelp: During dive and boat operations at the experimental sites and at natural kelp beds during sori collection it was often observed that areas in and around the kelp were used by individuals and schools of juvenile salmon, forage fish and resident fish species (e.g. shiner perch, rockfish) and invertebrates (crabs, caprellid amphipods). These observations are important confirmations of the ecological service of kelp beds as refuge and feeding sites for many fish and invertebrate species in the Salish Sea.

    Comparison with the previous years (2014, 2015 and 2016) of observations:

    1. A major difference between environmental conditions observed in 2017 and those in 2014 and 2015 was that temperatures in 2017 were consistently lower during spring (March to June) but rose to high levels (19 to 21 C) starting in late June through August whereas temperatures in June and July 2015 dipped from above to below 15°C for periods of about a week, whereas in 2014 temperatures continued above 15°C and even 18°C for prolonged periods (over 30 days). There appeared to be significant recovery of condition of many plants in 2015 and 2016 in these periods of respite from higher temperatures. However, kelp condition decline resumed in late July and August 2015, likely due to warm temperatures and the influence of epiphytes and epizoans, but remained quite healthy for many plants in 2016 into August and even October at the deeper, outer Maude site.

    Thus kelp condition at Maude Reef sites was better in the summer of 2016 than in 2015 and 2014 (as well as in 2017), resulting in persistence of healthy bull kelp plants into September and October, with significant sori production and release.

    Suggestions for Future Research

    The trend in several recent years (2013 -2015, 2017) of frequent prolonged periods of warm water (>15°C) in spring and/or summer months in areas of the Salish Sea such as Lambert Channel and Baynes Sound is a major challenge, along with heavy sea urchin grazing, to bull kelp restoration research and performance. In their on-going kelp research they propose the following approaches:

    1) To explore the selection of thermally tolerant bull kelp populations as parental stock for restoration planting. The planting work up to 2015 has used sori collected from kelp beds near Campbell River for production of kelp seed for planting at experimental sites. In September 2015, sori were also collected from the southern Gulf Islands area (Sansum Narrows) as well as Campbell River in order to compare the responses of kelp seed from these donor areas. Although F1 generations from both areas performed similarly at experimental sites in 2016, further trials will be conducted to select thermally hardy stocks with guidance from genetic study results and stress tests of various life history stages. Potential candidates for sori collection are the kelp bed adjacent to Stanley Park in Burrard Inlet and a bed near Oyster River, south of Campbell River.

    2) To study the developmental biology of bull kelp life stages under a range of temperatures in a laboratory setting. This is research by collaborators (Dr. Sherryl Bisgrove and Masters student, Braeden Schiltroth, of the Department of Biological Sciences at Simon Fraser University) to examine factors that limit bull kelp survival and development in the spore, gametophyte and early sporophyte stages.

    3) To continue investigation at the more successful two additional kelp study sites with more depth and greater exposure to currents and/or waves for potential temperature moderation. Sites at CLs and MO were demonstrated to be better in supporting bull kelp growth and maturation in 2016 so were retained in 2017.

    4) To investigate the wider use of “conditioned” rope for collection of “wild”set sporophytes at experimental and reference sites. This approach has potential to add to kelp restoration knowledge and to reproductive amplification in the study area, at low incremental cost.

    5) To investigate the reduction of sea urchin densities as a treatment to enhance recruitment success by bull kelp at selected sites with historical presence of kelp beds.

    A large difference in natural kelp distribution among 2017, 2016, 2015 and 2014 was the reduction in the presence of “wild” bull kelp along the southeastern Denman Island foreshore. Instead of the typical fringing kelp bed in this area, only about 50 bull kelp plants grew in one patch there in 2015 followed by the total lack of recruitment of bull kelp there in 2016 and 2017. Diving observations noted the large increase in green sea urchin abundance in this area in a band or zone above the red sea urchins typically observed. The resulting grazing pressure may have had a negative impact on bull kelp abundance. At the reference site, in previous years, it also seemed that competition by other algal species may limit the initial density of bull kelp sporophytes while grazing pressure from sea urchin species limits the depth range of the kelp, preventing colonization of the cooler depths below 6-7 m. In addition, the 2014 cohort of bull kelp at Denman Island had poor development and release of sori, a factor that could have strongly influenced the initial density of sporophytes in 2015 and 2016. In 2017 and 2016 there were observations of wild set bull kelp on long-term mooring lines at the kelp study sites.