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Sampling of Intertidal Invertebrates and Algae on Sheltered Rocky Shores

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Sampling of Intertidal Invertebrates and Algae on Sheltered Rocky Shores United States Department of the Interior FISH AND WILDLIFE SERVICE Alaska Peninsula/BecharofNWR P.O. Box277 King Salmon. AK 99613 (907) 246-3339 (voice) (907) 246-6696 (fax) December 13, 2010 Distribution List Dear Reader: During the summer of2010 the Alaska Peninsula/BecharofNational Wildlife Refuge supported a field project at Puale Bay on the Gulf of Alaska. The primary purpose Of the camp was to continue long-term monitoring of the seabird colony there. The camp was staffed by one technician and three interns. Each intern also lead another project and this resulted in the monitoring of the beach for dead animals, conducting a pilot study of the rocky intertidal, and monitoring plants for phenology. Enclosed are the reports and/or recommendations from this work. If you have questions or comments about the reports or projt;cts, please contact me at (907) 246- 1205 or susan [email protected]. ' Sincerely, / L~ /~., .. ___,,_}""-- susan Savage Wildlife Biologist Distribution List: Lem Butler* Alaska Dept. of Fish & Game, King Salmon Meghan Riley* Alaska Dept. ofFish & Game, King Salmon Vernon Byrd* Alaska Maritime NWR Donald Dragoo* Alaska Maritime NWR Nora Rojek* Alaska Maritime NWR Molly Chythlook Bristol Bay Native Association John Martin* Division of Natural Resources, USFWS, Region 7 Christine Peterson* IzembekNWR Troy Hamon* Katmai National Park Rocky & Phil Shoemak~r Kejulik River Residents Robin Corcoran* ! KodiakNWR Dave Irons* Migratory Bird Management, USFWS, Anchorage Robb Kaler* Migratory Bird Management, USFWS, Anchorage Scott Hatch* Pacific Seabird Monitoring Database, USGS, Alaska Science Center Heather Coletti* Southwest Alaska Network, NPS Mike Swaim* TogiakNWR 2010 Interns (3 copies)*~ King Salmon Visitor Center AK Resource Library & Information Service (1 copy+ PDF)* 7 ~v~' <-~ 1t.) 1.3 Alaska Peninsula Pei'111allent Staff (route 1 copy) . /--:) Alaska Peninsula Gray Lit File (original + PDF in files) '"+o (}.. f' c~.__ dC o -~'""-- Report Authors *Receive PDF Copy Rocky Interti al Survey Puale Bay 2010 Samplin of Intertidal Invertebrates and Algae on Sheltered Rocky Shores (after Dean and Bodkin, 2006) 2010 Report Summary Marla Greanya U.S. Fish and Wildlife Service Alaska Peninsula/Becharof NWR P.O. Box 277 King Salmon, AK 99613 Species asse blage in the sheltered rocky intertidal of the Gulf of Alaska is divided among three or four distinc vertical tidal elevations. The differing communities are influenced by physical characteristic such as substrate and tidal pressure (Dean and Bodkin 2006). A pilot study investigating e intertidal invertebrates and algae present in the sheltered rocky shore at Puale Bay (57.7495 9°N, -155.6118°W), located on the Pacific side of the Alaska Peninsula (Figure 1) and bordering Alaska Peninsula/BecharofNational Wildlife Refuge (AKPB), was conducted during the mo thly low ebb of July 2010. This study was adapted from a National Park Service protocol devis d by Dean and Bodkin (2006). The focus of this pilot study is to obtain data on the presence a d density of intertidal organisms along coastal areas bordering AKPB. This will provide a bas line for monitoring potential changes due to impacts such as climate change or oil spills, as mari e invertebrates are good biological indicators of change (Coletti et al. 2009). METHODS Sampling was conducted in the rocky intertidal zone abutting a 400 foot cliff face supporting a small seabird olony of3,000-5,000 birds. The sampling site was selected based on ease of access, as it is the only rocky intertidal beach accessible by foot in the area. Uncertainties in 1 Rocky Intertidal Survey Puale Bay 2010 logistics and a narrow sampling window due to incoming tide resulted in sampling conducted over a two day period (12 and 13 July 20 10). Mean lower low water (MLL W) of -1.07 m occurred on 13 July at 10:19 am. A total of five distinct 50 m transects at differing tidal elevations were sampled for various intertidal organisms. The transects were at MLL W, 0.5 m above MLL W, 1.5 m above MLL W, at the highest density of Pacific blue mussels (Mytilus trossulus), and at the highest density of limpets (Lottia spp.) Percent cover and occurrence of algae and sessile invertebrates were sampled at the transects 0.5 m and 1.5 m above MLL W. A 0.25 m2 quadrat was placed at the 1 m mark, the 5 m mark, and at 5 m intervals thereafter (the protocol was slightly deviated from; see discussion), resulting in ten sampling points per transect. Monofilament was stretched across the frame starting at 5 em from each edge and then at 10 em intervals, which produced a quadrat with 25 crosshairs. Each crosshair was painted with fluorescent orange paint to increase crosshair visibility. Sampling frames were placed such that the lower left comer of the frame, when facing the shoreline, was placed at the start point of the sampling interval. The substrate within the sampling area was first recorded, followed by the algae and sessile organisms present under each crosshair. Using a tent stake, each layer of algae was recorded and moved aside until the abiotic substrate was encountered. Other organisms that occurred within the quadrat but did not fall under a crosshair were also recorded. Organisms that could not be identified were given a descriptive name and collected or photographed for later identification. The density of black katy chitons (Katharina tunicata) and whelks (Nucella spp.) were sampled at the transects 0.5 m and 1.5 m above MLL W. A 1 m2 quadrat was placed at the 0 m mark and at 5 m intervals thereafter, resulting in ten sampling points per transect. The quadrat was first placed upslope of the transect line and then flipped below, covering a 2m2 sampling area at each interval. All Katharina tunicata and Nucella spp. were counted above and below overhanging rocks, but algae and other substrate were not moved. The size distribution and density of M trossulus and Lottia spp. were sampled at two unique transects, each located about 2-3 m above MLL Wand perpendicular to the shore, which were selected by visually estimating areas of greatest respective density. Using an adjustable circular plot, sampling began at the 1 m mark and followed at 8 m intervals thereafter, resulting in six sampling points at each transect. The sampling area was adjusted so that the smallest radius · would include at least twenty mussels and limpets, respectively. The area of the circle could range from a 10 em radius (0.0314 m2 area) to a 1m radius (3.14 m2 area). All individuals that fell within the circle were counted, and the first twenty encountered when moving in a clockwise direction (beginning upslope) were measured. Large invertebrates such as sea stars, anemones, chitons, and hermit crabs were counted on the upslope side ofthe MLLW level in a 4 m wide by 50 m long transect, resulting in a 200m2 sampling area. Two observers walked the length of the transect each carrying a 2 m rod held perpendicularly to the transect as guidance. Individuals were identified if possible, or given a descriptive name and pictures taken for later identification. All individuals were counted above and belowoverhanging rocks, but algae and other substrate were not moved. 2 Puale Bay 201 0 The sampli g area and the end of each transect was recorded using a Garmin GPS 76S. Due to the close pr ximity to the cliff, the accuracy of the points is questionable. However, unless there is a need to onitor the Sl,lme location throughout time - in which permanent anchors would be appropriate r site photographs and GPS points will allow observers to re-survey approximately the same loqation. Slope was also determined at both ends ofthe transects using a stadia rod and inclinometer, beginning at MLLW and extending 50 m up shore. PUALN BAy Figure 1. Location of rocky intertidal study site with an inset of an overview of Puale Bay, Alaska Peninsula!BecharofNWR. RESULTS The substdte was composed primarily of large rocks (>1 m diam.) and boulders (300 mm to <1 m diam.), with intermittent areas of cobble (50 mm to <300 mm diam.) and sand (<1 mm diam.). Both air ano water temperature at the time of sampling was 11° C and water salinity was 1.025 d~. 20 Using 0.25 m2 quadrats, measurements of percent cover documented 18 species of sessile invertebrat s and algae (Appendix I). The lower elevation transect (0.5 m above MLL W) had 16 species (89 2 ±16.8 percent cover), while the higher tidal elevation transect (1.5 m above MLL W) c ntained 8 species (70.8 ±26.1 percent cover; Table 1). There was greater percent cover of al ae in the 0.5 m transect (89 .2 ± 16.8 percent cover) compared to the 1.5 m transect (59.2 ±25. percent cover), but the 1.5 m transect had a greater percent cover of invertebrates than the 0. m transect (32.4 ±25.5 and 15.2 ±18.3 percent cover, respectively). Species that fell 3 Rocky Intertidal Survey Puale Bay 201 0 within the quadrat but not under a crosshair were recorded, but none were unique. The abiotic substrate ofboth transects was similar. 0.5 m 0.5m 1.5 m 1.5m Interval algae inverts Total 0.5 m% cover algae inverts Total 1.5 m %cover 1 100 24 100 72 72 92 2 60 20 60 52 56 76 3 100 48 100 64 36 64 4 100 0 100 40 68 72 5 100 4 100 92 0 92 6 96 0 96 64 16 80 7 96 4 96 52 16 60 8 92 44 92 0 4 4 9 92 0 92 84 28 92 lO 56 8 56 72 28 76 AVG%COVER 89.2 15.2 89.2 59.2 32.4 70.8 SD 16.8 18.3 16.8 25.9 25.5 26.1 Table 1.
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