Damage assessment and site characterization of the rocky shore following the grounding and recovery of the F/V Lou Denny Wayne
- Steve Lonhart
Monterey Bay National Marine Sanctuary
- Erica Burton
Monterey Bay National Marine Sanctuary
On November 29, 2007 at approximately 0130 hours the F/V LOU DENNY WAYNE (hereafter LDW) ran aground one mile south of Pigeon Point, San Mateo County, California (Figs. 1, 2). Coast Guard Sector San Francisco, in close coordination with NOAA (the Monterey Bay National Marine Sanctuary), the Office of Spill Prevention and Response (California Department of Fish and Game) and the San Mateo County Sheriff Department, worked with Parker Diving to remove the diesel fuel on board the LDW since it was considered a substantial threat to the environment. The vessel owner estimated up to 600 gallons of diesel fuel was on board the vessel at the time of the incident and an estimated 370 gallons of diesel fuel were recovered from the LDW.
Research staff from the Monterey Bay National Marine Sanctuary (MBNMS) made several visits to the grounding site of the LDW. The initial visit occurred at 0830 on November 30, 2007. Tidal conditions during the initial visit were not optimal for a research survey. Plans were subsequently made to revisit the site during low (or minus) tides to better access the wreck and impacted area. Second and third visits by research staff were made on December 6 and December 22, 2007, seven and twenty-three days after the incident, respectively. The goal of these latter two visits was to assess the status of natural resources (both biological and geological) within and adjacent to the grounding site of the LDW.
Summary to DateOn December 6, 2007 research staff from MBNMS evaluated the site from 1400 to 1530 hr when the tidal height was -0.23 ft at 1438 at Ano Nuevo Island. During the first 30 min a contracted helicopter hauled away three net loads, and shortly thereafter the rest of the cleaning crew left the scene. The boat’s engine had just been removed and some residual diesel spilled during transportation (Scott Kathey, personal communication). A slight sheen was visible on the surface of the water closest to shore, and it was also evident in at least one small tidepool (<1 m2) where there was a strong smell of fuel and an oily sheen.
Initially researchers inspected the area where the majority of wreckage had been according to Scott Kathey (MBNMS staff) and the clean-up supervisor/company owner. Researchers estimate 10 m2 of freshly broken sedimentary rock was exposed. Weathered rock was dark or dull in appearance with worn/smoothed edges, whereas newly exposed rock was lighter in color, had evidence of sharp edges and was free of attached epibionts. Nearly 5 m2 of surf grass was exposed at this time at the site of the boat grounding.
Black turban snails Tegula funebralis, up to ~100 per 0.25 m2, were very common in both impact site and adjacent areas. The ochre star Pisaster ochraceus (not very large [<15 cm diameter], purple and orange color morphs) was also observed in and beyond the impact site. The California mussel Mytilus californianus was not observed. The green alga Codium setchellii was noted in one patch (20 cm long, 5 cm wide). Owl limpets Lottia gigantea, <5 per m2, were mostly medium-sized and found in both the impact site and adjacent areas. The sea palm Postelsia palmaeformis was present on offshore rocks, beyond an area where the green rope and white floats from the LDW were wrapped around rocky outcrops.
- No trends were apparent given the short interval between the grounding (November 30, 2007) and the two site visits (December 6 and 22, 2007).
DiscussionDamage from the grounding and recovery appeared to be minimal (e.g., approximately 10 m2 of freshly broken sedimentary rock exposed at low tide; slight differences in percent cover of algae and invertebrates between survey transects). A diesel sheen was present in tidepools and the surrounding area during the December 6 survey. Small pieces of trash were also observed in the subtidal and wash zones. The site will be revisited in the future to monitor changes at the three transects.
- Substrate characterization
- Dispersal & Recruitment
Study MethodsVisual inspection
On December 6, 2007 researchers recorded direct observations of the site, including the
types of debris remaining, evidence of diesel fuel, and physical damage to the rocky shore itself. Information was collected for the site as a whole, and specifically at the site of impact.
During both site visits, numerous digital photographs were taken of the site. These included overview images from atop the cliffs and close-ups of the rocky intertidal and sandy beach. On December 22, 2007 photos were also taken of the three vertical transects, covering the entire length of the transect to a width of about 1 m. Photographs were taken while standing adjacent to the transect, centering the line in the middle of the image.
Vertical transects were sampled using the uniform point contact (UPC) technique. Points along the transect were sampled at an interval of 0.5 m, starting at the 30 m end (seaward edge) and ending near 0 m (shoreward edge) along the intertidal (length of transect varied slightly). At each point data are collected to determine relative abundance (% cover) of species occupying primary space. Relative abundance data are collected by identifying the taxon that falls directly under a point, including abiotic features (e.g., bare rock, cobble, sand, and tar). In this study of the LDW site, information on layering (i.e. multiple taxa occupying the same point) was not collected; only the primary space occupier was recorded.
On December 6, 2007 researchers laid three transects running perpendicular from shore to sea (Fig. 3). The 0 m end of the transect tape was anchored at the transition zone where solid rocky shore was covered by the start of the beach. The transect tape was laid perpendicular to shore on a heading of 210 degrees. The transect tape was loosely draped over the surface and extended out 30 m or until the rocky shore was submerged, whichever came first. Once the transect was in place, Dr. Steve Lonhart observed what was under each 0.5 m point and called out the taxon for Erica Burton to record on a data sheet. Three transects were completed in this manner, one at the site of impact, one adjacent to the site of impact, and one roughly 30 m to the south of the impact site as an undisturbed reference.
On December 22, 2007 the same UPC method was used but only Dr. Lonhart was present to record information. The two transects near the impact site were repeated but the undisturbed reference was at a slightly different location.
Figures and Images
Figure 1. F/V Lou Denny Wayne grounding, approximately 1.4 miles SE of Pigeon Point, California (12/03/07). Photo: Scott Kathey
Figure 2. Grounding site of F/V Lou Denny Wayne (red arrow), approximately 1.4 miles SE of Pigeon Point, California. Photo: California Coastal Records Project, with permission.
Figure 3. Removal of trash from F/V Lou Denny Wayne grounding site (12/06/07).
Figure 4. Transect #1 on southern side of channel. An area that appeared to be less impacted than the northern side of channel (12/06/07). The boat has already been removed.