Resilience of Green Sea Urchin (Strongylocentrotus droebachiensis) Populations Following Fishing Mortality: Marine Protected Areas, Alternate Stable States, and Larval Ecology

The green sea urchin Strongylocentrotus droebachiensis has been aggressively fished in Maine since 1986 resulting in severe population declines throughout portions of the state. This research used Marine Protected Areas (MPAs) to evaluate the potential for recovery in depleted sea urchin populations. It was necessary to not only look at the direct impacts of the MPAs, but also at larval transport / supply and community interactions to gain a better understanding of the system. We found that MPAs in the Gulf of ~a!ne were of varied utility to restoring depleted sea urchin populations depending on location and community structure. MPAs established in coralline communities appeared to protect sea urchin populations from further declines and may have allowed some slow recovery. However, closures in areas that have undergone a community shift from coralline communities to fleshy macroalgal beds did not provide protection for the remaining sea urchins or appropriate habitat for repopulation. Additionally, this macroalgal state appears stable over time so the potential for sea urchin recovery will probably remain low. This study also determined the point at which sea urchins could no longer control macroalgal production and allowed the growth of fleshy macroalgal beds. This ecologically effective biomass declined exponentially with water depth and was inversely proportional to latitude. These patterns were probably caused by the factors that affect productivity (e.g. light, nutrients) and grazing rates (e.g. temperature, water movement). Mechanisms driving sea urchin settlement were also examined. Competent echinoplutei were found higher in the water and advected onshore when northeast wind events created oceanographic downwelling conditions. Newly metamorphosed sea urchins were also found in the water column, suggesting that contact with the substrate is not needed to initiate metamorphosis. Sea urchin settlement was greatest in coralline communities with high micro-complexity and lowest in macroalgal beds. Survival through the summer, however, only averaged 50% regardless of community type or habitat micro-complexity. Lastly, this study identified adult sea urchins as a potential consumer of juvenile sea urchins, which may account for some of the relatively high mortality seen in sea urchin-dominated coralline communitie

Fourth Annual Report: 2007 Pre-Construction Eelgrass Monitoring and Propagation for King County Outfall Mitigation

King County proposes to build a new sewer outfall discharging to Puget Sound near Point Wells, Washington. Construction is scheduled for 2008. The Point Wells site was selected to minimize effects on the nearshore marine environment, but unavoidable impacts to eelgrass (Zostera marina) beds are anticipated during construction. To mitigate these impacts and prepare for post-construction restoration, King County began implementing a multiyear eelgrass monitoring and restoration program in 2004, with the primary goal of returning intertidal and shallow subtidal habitat and eelgrass to pre-construction conditions. Major program elements related to eelgrass are (a) pre-construction monitoring, i.e., documenting initial eelgrass conditions and degree of fluctuation over 5 years prior to construction, (b) eelgrass transplanting, including harvesting, offsite propagating, and stockpiling of local plants for post-construction planting, and (c) post-construction planting and subsequent monitoring. The program is detailed in the Eelgrass Restoration and Biological Resources Implementation Workplan (King County 2006). This report describes calendar year 2007 pre-construction activities conducted by Pacific Northwest National Laboratory (PNNL) for King County. Activities included continued propagation of eelgrass shoots at the PNNL Marine Sciences Laboratory (MSL) in Sequim, Washington, and monitoring of the experimental harvest plots in the marine outfall corridor area to evaluate recovery rates relative to harvest rates. In addition, 490 eelgrass shoots were also harvested from the Marine Outfall Corridor in July 2007 to supplement the plants in the propagation tank at the MSL, bringing the total number of shoots to 1464. Eelgrass densities were monitored in four of five experimental harvest plots established in the Marine Outfall Corridor. Changes in eelgrass density were evaluated in year-to-year comparisons with initial harvest rates. A net increase in eelgrass density from 2004 post-harvest to 2007 was observed in all plots, despite density decreases observed in 2006 in all plots and at most harvest rates. Eelgrass densities within individual subplots were highly variable from year to year, and the change in density in any interannual period was not related to initial 2004 harvest rate. Harvest rates of neighboring subplots did not appear to affect subplot eelgrass density (Woodruff et al. 2007). Three years post-harvest, eelgrass shoot densities were not significantly different from pre-harvest shoot densities at any harvest level. Additional plans are being discussed with King County to harvest all eelgrass from the construction corridor and hold in the propagation tanks at the MSL for post-construction planting. Under this plan, plants that would have been lost to construction will be held offsite until construction is completed. This strategy reduces and possibly eliminates the need to harvest eelgrass from donor beds located south of the construction area, allowing them to remain undisturbed. However, if eelgrass is harvested from donor beds, the monitoring of eelgrass growth at different harvest rates should help determine an optimum harvest rate that supports rapid recovery of donor eelgrass beds

Is local adaptation a factor in planning eelgrass restoration? Initial assessment of responses to temperature by eelgrass growing across a stressor gradient

Large-scale eelgrass restoration in an environment as complex as the Salish Sea requires estimating the effects of a wide range of environmental conditions (e.g. temperature, salinity, turbidity) on the effectiveness of restoration actions in different locations. We have developed a spatial model of eelgrass growth in response to environmental drivers, based on physiological data collected in Sequim Bay, WA, to aid in identifying restoration sites. However, field tests suggest that the model underestimates the capability of eelgrass to grow in conditions more stressful than Sequim Bay. A critical uncertainty is the extent of localized genotypic and/or phenotypic adaptations by eelgrass to high temperature and light limitation, which would affect our ability to predict restoration success over large scales with a single model. We have conducted an initial set of experiments to explore the physiological response of eelgrass collected from multiple locations across a temperature stress gradient. We collected eelgrass samples from two high-stress locations (South Sound and Hood Canal), and one low-stress location (Sequim Bay) and measured photosynthesis and respiration rates of cleaned, healthy leaf sections via instantaneous oxygen flux in light and dark bottles across a range of temperatures. The samples had notable differences in morphology and epiphytes. We found that respiration and photosynthesis did not differ between sites across the temperature treatments. Counter to expectations, eelgrass from more stressful locations had higher respiration rates, though the difference was not statistically significant. We observed significantly higher gross and net productivity at 25° C for eelgrass from Hood Canal. The results suggest that eelgrass populations throughout Puget Sound may not be as differentially adapted to temperature as we expected, despite discrepancies between modeling and field observations. We hope to extend this study with additional data collection, including moderate- to long-term common garden growth experiments for multiple stressors

Eelgrass (Zostera marina) restoration in Puget Sound: restoration tools, successes and challenges

Eelgrass (Zostera marina) is one of 25 Vital Signs to track the health of Puget Sound and restoration of this critical nearshore habitat is part of the overall regional recovery strategy. Eelgrass restoration will provide a multitude of benefits, ranging from habitat for species to ameliorating the effects of climate change. Since 2013, the Washington State Department of Natural Resources has led regional evaluation of potential eelgrass restoration sites and transplanting in Washington State. Through collaborations we have developed and tested strategies to enhance transplant success and restore natural processes. We developed an eelgrass transplant suitability model to identify potential restoration sites using key variables essential for seagrass production and long-term resilience in a changing environment. Eelgrass was planted at five sites for initial model verification with an additional 81 test sites planted between 2013 and 2017 to identify areas suitable for large scale restoration. Eelgrass test transplant results varied and 15 sites with the highest success were selected for large-scale transplantation. A comparison of standard transplant methods was performed and preliminary results suggest that proper method selection plays an important role in transplant success. Long-term monitoring is scheduled with an emphasis on the success of specific donor stocks, the recovery of donor sites, and the effect seagrass restoration has on water chemistry. The restoration process has endured challenges that ranged from permitting issues to anthropogenic and environmental stressors. However, issue specific solutions and adaptive management allowed the restoration process to progress and contribute valuable information towards strategies to recover this valuable habitat in the region

Effects of burial by the disposal of dredged materials from the Columbia River on Pacific razor clams (Siliqua patula)

Annual maintenance of the Columbia River navigation channel requires the U.S. Army Corps of Engineers (Corps) to dredge sediment from the river and dispose of the sediment in coastal areas at the mouth of the Columbia River. Some of these disposal areas can be as shallow as 12 m deep in waters off the coastal beaches, and dredged material disposal activities have therefore raised concerns of impacts to local razor clam (Siliqua patula) populations that are prevalent in the area. The Corps’ Portland District requested that the Marine Sciences Laboratory of the U.S. Department of Energy’s Pacific Northwest National Laboratory conduct laboratory experiments to evaluate the potential impacts of burial by dredged material to razor clams during disposal. Prior modeling of disposal events indicates three stresses that could have an impact on benthic invertebrates: convective descent and bottom encounter (compression forces due to bottom impact), dynamic collapse and spreading (surge as material washes over the bottom), and mounding (burial by material). Because the razor clam is infaunal, the effects of the first two components should be minimal, because the clams should be protected by substrate that is not eroded in the event and by the clams’ rapid digging capabilities. The mound resulting from the disposal, however, would bury any clams remaining in the footprint under as much as 12 cm of new sediment according to modeling, and the clams’ reaction to such an event and to burial is not known. Although the literature suggests that razor clams may be negatively affected by siltation and therefore perhaps by dredging and disposal activity, as well, impacts of this type have not been demonstrated. The primary purpose of this study was to evaluate the potential impacts of dredge material disposal on adult subtidal razor clam populations at the mouth of the Columbia River. Using the parameters defined in a previous model, a laboratory study was created in which a slurry was added to experimental chambers seeded with adult razor clams to produce burial mounds of various thicknesses. The laboratory results presented here have two implications for disposal operations

Third Annual Report: 2006 Pre-Construction Eelgrass Monitoring and Propagation for King County Outfall Mitigation

King County proposes to build a new sewer outfall discharging to Puget Sound near Point Wells, Washington. Construction is scheduled for 2008. The Point Wells site was selected to minimize effects on the nearshore marine environment, but unavoidable impacts to eelgrass (Zostera marina) beds are anticipated during construction. To mitigate for these impacts and prepare for post-construction restoration, King County began implementation of a multi-year eelgrass monitoring and restoration program in 2004, with the primary goal of returning intertidal and shallow subtidal habitat and eelgrass to pre-construction conditions. Major program elements are a) pre-construction monitoring, i.e., documenting initial eelgrass conditions and degree of fluctuation over 5 years prior to construction, b) eelgrass transplanting, including harvesting, offsite propagating and stockpiling of local plantstock, and post-construction planting, and c) post-construction monitoring. The program is detailed in the Eelgrass Restoration and Biological Resources Implementation Workplan (King County 2006). This report describes calendar year 2006 pre-construction activities conducted by Pacific Northwest National Laboratory (PNNL) in support of King County. Activities included continued propagation of eelgrass shoots and monitoring of the experimental harvest plots in the marine outfall corridor area to evaluate recovery rates relative to harvest rates. Approximately 1500 additional shoots were harvested from the marine outfall corridor in August 2006 to supplement the plants in the propagation tank at the PNNL Marine Sciences Laboratory in Sequim, Washington, bringing the total number of shoots to 4732. Eelgrass densities were monitored in the five experimental harvest plots established in the marine outfall corridor. Changes in eelgrass density were evaluated in year-to-year comparisons with initial harvest rates. Net eelgrass density decreased from 2004 post-harvest to 2006 in all plots, despite density increases observed in 2005 in some plots and at some harvest rates. Eelgrass densities within individual subplots were highly variable from year to year, and the change in density in any interannual period did not correlate to the initial 2004 harvest rate. Continued monitoring should help project managers determine an optimum harvest rate that supports rapid recovery of donor eelgrass beds

Eelgrass donor sites: potentially overlooked impacts of restoration in Puget Sound

Eelgrass (Zostera marina) is an important habitat in the Salish Sea and restoration efforts are being undertaken around the region to increase eelgrass abundance and resilience. Eelgrass restoration is typically performed by transplanting whole shoots or dispersing viable seeds collected from reproductive shoots to a site. Most of the restoration efforts in the Pacific Northwest utilize whole shoots harvested from donor meadows and transplanted into restoration areas, but little work has been done to look at the impacts of the harvest on the donor stock. In response to the lack of existing data for Puget Sound, Washington Department of Natural Resources and Pacific Northwest National Laboratory’s Marine Sciences Laboratory conducted a controlled harvest experiment in two regions of the Salish Sea at sites associated with ongoing restoration activities. These meadows were harvested under different pressure (i.e., different percentage of plants taken from 0 to 50%) using traditional harvesting techniques. The meadows were then monitored for two years for changes in density. The results indicated that the eelgrass meadows were surprisingly resilient to all levels of harvest under ideal conditions and in small harvest areas. Interpretation and implications of these results will be discussed, as well as potential considerations for choosing potential donor sites for future restoration efforts

Evaluating Cumulative Ecosystem Response to Restoration Projects in the Columbia River Estuary, Annual Report 2005

This report is the second annual report of a six-year project to evaluate the cumulative effects of habitat restoration projects in the Columbia River Estuary, conducted by Pacific Northwest National Laboratory's Marine Sciences Laboratory, NOAA's National Marine Fisheries Service Pt. Adams Biological Field Station, and the Columbia River Estuary Study Taskforce for the US Army Corps of Engineers. In 2005, baseline data were collected on two restoration sites and two associated reference sites in the Columbia River estuary. The sites represent two habitat types of the estuary--brackish marsh and freshwater swamp--that have sustained substantial losses in area and that may play important roles for salmonids. Baseline data collected included vegetation and elevation surveys, above and below-ground biomass, water depth and temperature, nutrient flux, fish species composition, and channel geometry. Following baseline data collection, three kinds of restoration actions for hydrological reconnection were implemented in several locations on the sites: tidegate replacements (2) at Vera Slough, near the city of Astoria in Oregon State, and culvert replacements (2) and dike breaches (3) at Kandoll Farm in the Grays River watershed in Washington State. Limited post-restoration data were collected: photo points, nutrient flux, water depth and temperature, and channel cross-sections. In subsequent work, this and additional post-restoration data will be used in conjunction with data from other sites to estimate net effects of hydrological reconnection restoration projects throughout the estuary. This project is establishing methods for evaluating the effectiveness of individual projects and a framework for assessing estuary-wide cumulative effects including a protocol manual for monitoring restoration and reference sites

Evaluating Cumulative Ecosystem Response to Restoration Projects in the Lower Columbia River and Estuary, 2009

This is the sixth annual report of a seven-year project (2004 through 2010) to evaluate the cumulative effects of habitat restoration actions in the lower Columbia River and estuary (LCRE). The project, called the Cumulative Effects Study, is being conducted for the U.S. Army Corps of Engineers Portland District (USACE) by the Marine Sciences Laboratory of the Pacific Northwest National Laboratory (PNNL), the Pt. Adams Biological Field Station of the National Marine Fisheries Service (NMFS), the Columbia River Estuary Study Taskforce (CREST), and the University of Washington. The goal of the Cumulative Effects Study is to develop a methodology to evaluate the cumulative effects of multiple habitat restoration projects intended to benefit ecosystems supporting juvenile salmonids in the 235-km-long LCRE. Literature review in 2004 revealed no existing methods for such an evaluation and suggested that cumulative effects could be additive or synergistic. From 2005 through 2009, annual field research involved intensive, comparative studies paired by habitat type (tidal swamp versus marsh), trajectory (restoration versus reference site), and restoration action (tidegate replacement vs. culvert replacement vs. dike breach)

Laboratory Assessment of Potential Impacts to Dungeness Crabs from Disposal of Dredged Material from the Columbia River

Dredging of the Columbia River navigation channel has raised concerns about dredging-related impacts on Dungeness crabs (Cancer magister) in the estuary, mouth of the estuary, and nearshore ocean areas adjacent to the Columbia River. The Portland District, U.S. Army Corps of Engineers engaged the Marine Sciences Laboratory (MSL) of the U.S. Department of Energy’s Pacific Northwest National Laboratory to review the state of knowledge and conduct studies concerning impacts on Dungeness crabs resulting from disposal during the Columbia River Channel Improvement Project and annual maintenance dredging in the mouth of the Columbia River. The present study concerns potential effects on Dungeness crabs from dredged material disposal specific to the mouth of the Columbia River