Big Sur Nearshore Characterization (BSNC)
- Steve Lonhart
Monterey Bay National Marine Sanctuary
The goal of this project is to further characterize the marine resources and habitats of the Big Sur coastline, particularly the nearshore subtidal. This project continues some of the marine resources surveys (project link) conducted from 2003 to 2005 as part of the Coast Highway Management Plan (CHMP) for Highway 1 in Big Sur.
We use field-tested methods to collect the following data at each new survey site:
1. Subtidal geology
2. Slope, bottom type, relief, exposure
3. Presence of invasive/managed/threatened/endangered species
4. Sensitivity to scour/burial/turbidity
5. Recovery potential
6. Species diversity for algae, invertebrates, and fishes
Site selection is based on two primary criteria:(1) sites that were modeled as part of the original marine resources survey but have not been validated by actual site visits, and (2) sites that have recently become protected through the State’s MPA process. Testing model results is a high priority, especially since more of the coastline is modeled than actually surveyed, and policy decisions by the Sanctuary may rely upon the model predictions. Further, the recent establishment of the California MPAs provides us with an excellent opportunity to collect before-after data and control-impact data (i.e. inside vs. outside an MPA).
Sampling kelp forests requires in situ observations. Unlike the majority of the Sanctuary, which can be viewed using a towed camera or ROV, the nearshore subtidal is dominated by canopy-forming algae, which precludes remote sensing techniques.
This project is long-term and the data will directly inform Sanctuary Action Plans, further establishing the Sanctuary as a leader in ecosystem-based management of resources along the Big Sur coast. Quantitative surveys of fishes, invertebrates, and algae along the Big Sur coast, such as those conducted annually by UC Santa Cruz's Partnership for Interdisciplinary Studies of Coastal Oceans (PISCO-UCSC), focus on a subset of species, particularly within the invertebrates and algae. The BSNC notes all macroscopic species encountered, providing species richness data that complement those collected by PISCO-UCSC.
Summary to DateIn 2009 we surveyed 11 sites along the Big Sur coast. During each cruise aboard the R/V FULMAR, we were able to dive multiple sites during excellent weather windows. The following sites were surveyed:
Lafler Rock 2
Willow Creek 2
Dogs (CalTrans site)
Mal Paso Sur
Hot Springs Canyon
San Martin Cove
20 mile marker
The following sites were sampled in 2008.
Rocky Point Restaurant
North Prewitt Creek
North Willow Creek
North Vicente Creek
South Little Sur River
Granite Canyon Lab
North Bixby Bridge
- It has been assumed that kelp cover is a good indication of bottom type. In general, this should be true, since canopy-forming kelps (e.g., Macrocystis and Nereocystis) must attach to solid substrates, such as large boulders or bedrock. However, we have found that thick canopies can be found over very sparse boulder fields, where most of the bottom is actually sand and the kelp is attached to the tops of the boulders, well above the shifting and scouring sands. Similarly, areas devoid of a kelp canopy may have solid rocky bottoms, but are covered with encrusting invertebrates (e.g., tunicates, sponges and bryozoans) and some low-lying algae.
DiscussionThe data collected by this project are used to inform sanctuary staff during the permitting process. Since landslides and road closures in Big Sur are a common occurrence along Highway 1 during the rainy season (typically November through April), the California Department of Transportations (CalTrans) must restore access to residents as quickly and efficiently as possible. Prior to the designation of the Monterey Bay National Marine Sanctuary, landslide materials (e.g., soil, rocks, dislodged vegetation) could be side-cast onto the slopes above the intertidal, and eventually discharge into the sanctuary. However, side-casting is now prohibited by the sanctuary and exceptions require a permit.
Prior to issuing a permit, sanctuary staff must carefully consider the various options of removing landslide debris, weighing the costs and benefits of each proposed remedy. An important aspect of determining the impact on marine resources, both in the intertidal and the subtidal, is knowing what lies below the landslide area. The BSNC project is the first comprehensive set of surveys to accurately characterize the communities of fishes, invertebrates, and algae that live in habitats close to shore and are most impacted by landslides and side-casting activities.
Ultimately the goal of the BSNC is to achieve extensive spatial coverage along the Big Sur coast. This entails diving along the coastline at 1-km intervals at least once. After completing this ambitious task, the next step will be to repeat some sites to evaluate temporal changes.
- Habitat association
- Non-indigenous species
- Substrate characterization
Study MethodsThe purpose of this project is to qualitatively estimate the abundance of major members of the kelp forest community at multiple sites in Big Sur. Three research divers (usually accompanied by one videographer and/or digital still phoptographer) visually survey the algae (Readdie/Kusic), invertebrates (Lonhart), and fishes (Carr/Pederson/King) at each of site. Sites are surveyed non-destructively, targeting macroscopic algae, invertebrates, and fishes found on primary substrate (e.g., rocks, reef, sand). Starting at the outer edge of the kelp forest, and at a depth of 60 ft (18 m), divers take a compass heading in to shore, swimming a transect through the kelp forest. Divers record all macroscopic species observed, in some cases recording only presence/absence, in others estimating counts. This process is repeated in each of three depth zones. Divers swim just above the bottom and make periodic stops (2-3 minutes) throughout the entire dive. Additional biological features, such as characteristic species groups and assemblages, are also noted.
Divers also record physical features of the kelp forest, including bottom type and geology, relief, sediment size, and slope. The survey data are collected within three subtidal depth zones: shallow = 0-5 m (<20 ft); mid-deep = 6-12 m (20-40 ft); and deep = 13-18 m (40-60 ft).
Each diver notes the presence of a species or taxon. In addition to presence/absence data, divers may also estimate the number of individuals seen. This is in the form of either a count estimate (e.g., 10-100 blue rockfish) or based on a five-step scale modified from the work of Smith and Gordon (1948) at the California Academy of Sciences. The categorical scale uses ranks 1 through 5, where
1 = rare (1-2 or less than 10% of average)
2 = few (less than average)
3 = average/typical (typical of what was seen across surveyed sites)
4 = abundant (above average abundance)
5 = very abundant (far more abundant >4 times than average)
Figures and Images
Figure 1. The study area spans from Point Pinos to Cambria. This map covers a section south of Point Lobos. Targeted dive sites are indicated by a dark blue bar (n=7 here).
Figure 2. Visual diver surveys are conducted by trained researchers from UC Santa Cruz and sanctuary staff.
Figure 4. There are several species of tunicate that are difficult to identify without dissection and taxonomic expertise. This may be a species of Didemnum.
Figure 3. Eric's Pinnacle had very high coverage of the strawberry anemone Corynactis californica from 13 m deep to near the top. There were several colors apparent, each likely representing a different clone.
Figure 5. Map of BSNC dive sites between Carmel River and Little Sur River along the Big Sur coast.
Figure 6. Map of BSNC dive sites between Point Sur and Esalen along the Big Sur coast.
Figure 7. Map of BSNC dive sites between Big Creek and San Carpoforo Creek along the Big Sur coast.