Santa Cruz Island Reserve

14 Mar, 01 PM - 20 Mar, 01 PM

This broad scale restoration study is intended to provide positive, cascading effects on rocky intertidal communities through the restoration of ecosystem-engineering rockweed species. These effects include survival and propagation of persistent rockweed populations, enhancements of biodiversity, and increases in the populations of key species at sites chosen for restoration. To measure the effects of restoration, we will conduct a) Comprehensive Biodiversity Surveys (CBS) and b) Rockweed Habitat Specific Surveys (RHSS). These data will be used to evaluate site-wide community change both temporally within sites and spatially across sites. RHSS will be used to evaluate restoration success in establishing rockweed populations, facilitating rockweed recruitment, and enhancing rockweed-associated community composition. Community structure will be assessed using Comprehensive Biodiversity Surveys (CBS) before restoration and 2 years following restoration, and compared to control areas to determine if restoration has enhanced species diversity and abundance. The CBS technique employs a series of parallel transect lines extending from the high intertidal zone to the low zone. To facilitate the setup of these lines, two permanent 30m horizontal baselines (parallel to the ocean) are first established. The upper baseline is placed in the high zone above the upper limit of the organisms, while the lower baseline, which should be parallel to the upper baseline, is established farther down the shore. The ends of these lines are permanently marked with either hex or carriage bolts. Once these two baselines have been established, parallel transect lines are run down the shore every three meters along the upper base line, following the contours of the substrate. To facilitate resurveys of the site, a map is drawn of the site showing the location of the bolts relative to notable landmarks or other, pre-existing permanent plots, GPS coordinates are recorded, and photographs are taken. In our study, we will use UAV maps for this purpose. The distance and bearing between the baseline end bolts will be measured. To monitor and measure the success of restoration, we will conduct Rockweed Habitat Specific Surveys (RHSS) prior to restoration and biannually for 2 years following restoration to monitor survival, growth, and reproductive potential of transplanted rockweeds, and recruitment of new rockweed. Recruitment will also be measured in control plots for comparison to restoration plots. Successful rocky intertidal restoration efforts are relatively rare, but rockweed reestablishment is a notable exception. Methods for successfully reestablishing rockweed populations have been identified through rigorous empirical testing, and we have been at the forefront of this research in California. Using proven restoration approaches, combined with testing of novel alternatives, we will restore impacted populations of key rockweed species, particularly Silvetia, across a broad spatial region (from San Diego to the Big Sur Coast, including the Channel Islands) to achieve stable and persistent rockweed populations that provide key ecosystem functions and benefits to rocky intertidal ecosystems. Within the geographical scope of this project, a minimum of 9 study sites each encompassing ~30-100 linear m of shoreline will be established based on relevant criteria, including available historical data on rockweed distribution, proximity to potential donor rockweed populations, population genetic structure, and ability to secure access permission and necessary permits. Sites that have historically supported healthy rockweed populations that have since been extirpated will be prioritized. These sites will be spread across the impact area, with 3 Channel Island sites and 3 sites each in the southern and northern mainland impact region. The primary restoration approach will involve transplanting fertile adults from donor sites to targeted restoration sites, based on methods developed and successfully employed by Whitaker et al. (2010) and Tronske and Smith (in prep). Donor sites will be chosen based on population size to minimize any impacts on the persistence of the donor population from the removal of outplants. We have identified several locations where we are confident that the donor population size is abundant enough for this purpose. For example, surveys at a potential donor site in Newport Beach found an average of 45 Silvetia individuals per m2 with the total area of donor beds extending well beyond 400 m2, thus consisting of ~18,000 individuals. Thus, removing 500 outplants at this site would affect <3% of the donor population. We plan to keep the impact of removals as small as practicable, maximally below 5% of the donor population, well within the range of natural interannual fluctuations, which are often >10% and can be larger (Graham et al. 2018, Raimondi et al. unpublished data). Individual Silvetia plants will be removed from the substrate at the donor site, spreading removal across the entire donor population as to not greatly decrease the density in any specific small area. Adult reproductively fertile Silvetia thalli (15–40 cm in length) will be targeted. Small pieces of rock will be removed under each plant using a diamond saw or rock hammer and chisel depending on the rock type and hardness. If plants can be found on cobbles those will be used as well. Plants will be transported in a cooler, wrapped in wet cloth to minimize desiccation stress. At the restoration site, plants will then be affixed to natural depressions in the rock using marine epoxy (Z-Spar) in appropriate habitats and tidal levels determined prior to the transplant effort. We will target north-facing slopes which were previously shown to result in partial shading and significantly higher survival rates. Additionally, preference will be placed on transplanting thalli onto substrata dominated by turf-forming algae (e.g., Endocladia muricata) which have been observed to facilitate recruitment and greatly increase survival of Silvetia (Brawley and Johnson 1991). Donor and restoration sites will be mapped with UAV surveys (see below) in advance of relocation, and the tidal height of restoration plots measured. Donor plants will be chosen from matching plots with respect to tidal height at the donor sites, individually labeled and relocated to the new plots at the restoration site. To measure the effects of restoration, we will conduct a) Comprehensive Biodiversity Surveys (CBS) and b) Rockweed Habitat Specific Surveys (RHSS). These data will be used to evaluate site-wide community change both temporally within sites and spatially across sites. RHSS will be used to evaluate restoration success in establishing rockweed populations, facilitating rockweed recruitment, and enhancing rockweed-associated community composition. Community structure will be assessed using Comprehensive Biodiversity Surveys (CBS) 2 years following restoration to determine if restoration has enhanced species diversity and abundance. The Community diversity (species richness and diversity indices) and abundance of key species (e.g. mussels, limpets) at recipient sites will be compared using Before-After Control-Impact (BACI) methods, evaluating whether diversity and abundance at restoration sites increased significantly relative to control sites. Control sites will be near recipient sites and chosen based on their similarity to the restoration sites. Rockweed Habitat Specific Surveys (RHSS) will be conducted at all donor sites biannually for 2 years following restoration to assess potential impacts resulting from transplant removal. Emphasis will be placed on documenting survival, growth and reproductive potential of transplanted rockweeds, and the recruitment of new rockweeds. Recruitment will also be measured in control plots and compared to restoration plots using a BACI approach. To map changes in rockweed abundance over a larger area, we will conduct aerial surveys two years following restoration at the recipient and donor sites using an UAV. We will augment the total number of transplants at each recipient site to maintain a survival rate ≥60% over the duration of the project period.

Visit #75254 @Santa Cruz Island Reserve

Approved

Under Project # 48494 | Research

Silvetia Restoration

professional - Channel Islands National Park

Reservation Members(s)

Stephen Whitaker Mar 14 - 20, 2022 (7 days)
Keith Lombardo Mar 14 - 20, 2022 (7 days)
Mike Ready Mar 14 - 20, 2022 (7 days)
Tavio del Rio Mar 14 - 20, 2022 (7 days)

Reserve Resources(s) | Create Invoice

Dock to Reserve Round-Trip 4 Mar 14 - 20, 2022
Regular Bunkroom 5 Mar 17 - 20, 2022
Vehicle Use - By Day 1 Mar 14 - 18, 2022
Vehicle Mileage 60 Mar 14 - 18, 2022
Christy Ranch Facilities Use 4 Mar 14 - 17, 2022