Rocky Reef Ecology

We perform studies of the rocky reef ecology of Southern and Baja California using a variety of different methods. We have been monitoring fish populations at all life stages in southern California since 1974.

Habitat Restoration Projects

Current restoration projects include kelp bed restoration and subtidal reefing—the largest and most extensive field research projects of their type in southern California.

Palos Verdes Reef Restoration Project

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At present, in the region of the peninsula between Portuguese Bend and Point Fermin much of the historic low-lying reefs continue to be heavily impacted by sedimentation due to reef burial and scour from these historic landslides. The only healthy reefs in the area are characterized by high-relief rocky outcrops that are resistant to the effects of sedimentation.

The Palos Verdes Reef Restoration Project seeks to restore rocky-reef habitat by emulating the form of the most productive extant reef in the region, KOU Rock (right), which consistently has greater fish biomass than any other reef on the peninsula.

Funding Source: NOAA Montrose Settlements Restoration Program

Lead Staff Researchers: Jonathan Williams, Matt Robart

Publications: Restoring a nearshore rocky reef ecosystem in the challenge of an urban setting (Pondella et al. 2018)

Presentations: Poster at GEOHAB Conference 2018

Kelp Forest Restoration

Adjacent to the largest urban area on the west coast of the United States, kelp forests in Santa Monica Bay are directly affected by anthropogenic impacts associated with urban development and population increase. These include an extensive and diverse set of stressors including commercial and recreational fishing, sedimentation, urban runoff, and pollution. Subtidal observations by Santa Monica Baykeeper in 2010 identified 61.5 hectares of nearshore rocky reef that were dominated by high densities of purple sea urchins and devoid of kelp. Subsequent community monitoring efforts have further qualified these barrens as areas featuring low diversity and productivity relative to areas of the Palos Verdes Peninsula that were currently supporting temporally and spatially stable giant kelp forests. Further, the urchins in these barrens are in poor physical condition with low gonadosomatic indices relative to urchins in neighboring kelp forests. The persistence of these urchin barrens, especially in the context of favorable conditions for giant kelp recruitment and development in southern California, argues for the active restoration of these barren reefs. The goals of this project is to reduce the density of purple sea urchins (Strongylocentrotus purpuratus) to two per square meter within the boundaries of sea urchin barrens off the Palos Verdes Peninsula, which will in turn minimize sea urchin grazing pressure and restore biogenic habitat to rocky reefs that historically supported kelp forests. Over time this will increase the spatial and temporal stability, biomass, and production associated with kelp forests and rocky reefs on the Palos Verdes Peninsula. The VRG assesses the response of these communities to restoration activities through annual subtidal monitoring at restoration sites.

 

 

Funding Source: NOAA Montrose Settlements Restoration Program

 

Partners: The Bay Foundation, Los Angeles County Sanitation Districts, Commercial Sea Urchin Harvesters

 

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Jonathan Williams

 

Publications: Kelp forest habitat restoration has the potential to increase sea urchin gonad biomass (Claisse et al. 2013)

Predicting Optimal Sites for Artificial Reefs

Habitat restoration is an important tool for managing degraded ecosystems, yet the success of restoration projects depends in part on adequately identifying preferred sites for restoration. Species distribution modeling using a machine learning approach provides novel tools for mapping areas of interest for restoration projects. Here we use stacked-species distribution models (s-SDMs) to identify candidate locations for installment of manmade reefs, a useful management tool for restoring structural habitat complexity and the associated biota in marine ecosystems. We created species distribution models for 21 species of commercial, recreational, ecological, or conservation importance within the Southern California Bight based on observations from long-term reef surveys combined with high resolution (200 x 200m) geospatial environmental data layers. We then combined the individual species models to create a stacked-species habitat suitability map, identifying over 800 km2of potential area for reef restoration within the Bight. The stacked-species distribution model provides insight for marine restoration projects in southern California specifically, but more generally this method can also be widely applied to other types of habitat restoration including both marine and terrestrial.

Funding Source: NOAA Saltonstall-Kennedy Grant

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Amanda Zellmer

Publications: Predicting optimal sites for ecosystem restoration using multi-species distribution modeling (Zellmer et a. 2019)

 

Long-Term Monitoring

Diver transects and ichthyoplankton studies are an integral part of our research and are among the longest continuous studies of reef fishes in the world.

CRANE Subtidal Reef Monitoring

We have led the region in developing Southern California Bight-wide research programs. Working with 26 state, federal and local agencies, NGOs, and university scientists, we have developed a region-wide monitoring protocol and network for rocky reef research. We led the development and implementation of the CRANE (Cooperative Research and Assessment of Nearshore Ecosystems) protocol that has led to the only bight-wide regional assessments of rocky reefs conducted to date. These include CRANE 2004, SCCWRPs Bight ’08, and MPA Monitoring Enterprises baseline assessment in 2011 and 2012, and MPA monitoring program in 2019 and 2020.

Fish Surveys at King Harbor and Rocky Point

We have been performing timed fish transects at several stations throughout King Harbor and near Rocky Point, Palos Verdes on a quarterly basis since 1974. Number and age class of every fish species encountered along the transect is recorded at a variety of depths along the artificial reefs and sand basins created by the harbor and at the extensive kelp forest off of Rocky Point.

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 Jonathan Williams

Publications: Fish production of a temperate artificial reef based on Enbiotocid density (Pondella et al. 2002)Factors affecting the abundance of juvenile fish species on a temperate artificial reef (Pondella & Stephens 1994)Overview of the dynamics of an urban artifical reef assmblage: a recruitment driven system (Stephens et al. 1994)

Ichthyoplankton of King Harbor

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Zoe Scholz

Taxonomists: Gary Jordan, Daniel Ramirez

Publications: The ichthyoplankton of King Harbor 1974-2009 (Pondella et al. 2012), Larval productivity of a mature artificial reef (Stephens & Pondella 2002), Overview of the dynamics of an urban artificial reef assemblage: a recruitment driven system (Stephens et al. 1994)