Spatial and Temporal Variation in Recruitment to Rocky Shores 

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FINAL TECHNICAL SUMMARY 

STUDY TITLE: Spatial and Temporal Variation in Recruitment to Rocky Shores: 

Relationship to Recovery Rates of Intertidal Communities 

REPORT TITLE: Spatial and Temporal Variation in Recruitment to Rocky Shores: 

Relationship to Recovery Rates of Intertidal Communities 

CONTRACT NUMBER: 14-35-0001-31063 

SPONSORING OCS REGION: Pacific 

APPLICABLE PLANNING AREA(S): Southern California 

FISCAL YEAR(S) OF PROJECT FUNDING: FY 03, FY 04, FY 05, FY 06 

COMPLETION DATE OF REPORT: March 2007 

COSTS: FY 03: $31,708; FY 04: $31,708; FY 05: $31,708 FY06: $31,708 

CUMULATIVE PROJECT COST: $126,835 

PROJECT MANAGERS: Russell J. Schmitt

AFFILIATION: Coastal Research Center, Marine Science Institute, University of 

California, Santa Barbara, CA 93106 

ADDRESS: University of California, Santa Barbara, CA 93106 

REPORT AUTHORS: Tish Conway-Cranos1 and Peter T. Raimondi1

PRINCIPAL INVESTIGATORS: Peter Raimondi1 and Richard Ambrose2

ADDRESSES: 1

Department of Ecology and Evolutionary Biology, University of 

California, Santa Cruz, CA 95060 2School of Public Health, Department of Environmental 

Sciences, University of California, Los Angeles, CA 90095-1772 

KEY WORDS: Recovery, succession, rocky intertidal, recruitment, Chthamalus, Mytilus, 

Endocladia, Silvetia

BACKGROUND: Community dynamics in the rocky intertidal may be governed to a 

large extent by the process of recovery after a disturbance, which may be variable across 

biogeographic regions or intertidal taxa. This study investigates the recovery process by 

performing experimental disturbances at three sites along the California coast in four 

different intertidal assemblages. Recruitment could be a key driver of recovery rates so we 
Final Technical Summary – Raimondi and Ambrose 

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measured the recruitment rate of each target species to see if recruitment is responsible for 

driving observed differences in recovery rate and trajectories. 

OBJECTIVES: The goals of this study were, broadly, to determine which processes were 

most important in driving recovery rates in rocky intertidal assemblages and more specifically 

to address the following questions: 

1. How do recovery dynamics change with biogeographic region? 

2. Is recruitment rate a good predictor of recovery rate? 

3. To what extent does disturbance magnitude (area) drive recovery processes at both the 

population and community level? 

4. How do species with differing life history characteristics respond to disturbance? 

DESCRIPTION: We made experimental clearings in an array of sizes at three sites along 

the California coast. Each site was chosen for its proximity to a long-term monitoring site 

and its location as north, near to or south of Point Conception, a major biogeographic 

barrier along the west coast of the United States. At each site, clearings were located in 

four different intertidal zones dominated by species with differing combinations of life 

history characteristics. The species chosen were Mytilus californianus, Silvetia compressa, 

Endocladia muricata and Chthamalus dalli/fissus. We also established control 

(unmanipulated) plots in each intertidal assemblage. We tracked the recovery of these 

clearings by assessing the percent cover of benthic invertebrates and algae in recovery and 

control plots over time. To determine the extent to which recruitment drives recovery rates, 

we measured recruitment onto natural and artificial substrata for each target species. 

SIGNIFICANT CONCLUSIONS: 

• Recovery rate as a function of initial disturbance size was distinctly different across 

sites and rocky intertidal assemblages such that for the Chthamalus assemblage, there 

was significantly negative relationship between initial disturbance size and recovery 

rate near Point Conception but no relationship at the sites north and south of Point 

Conception. For Mytilus, there was a significantly negative relationship between initial 

disturbance size and recovery rate at all three sites. For Endocladia, at Point Sierra 

Nevada (north of Point Conception), there was a negative relationship between initial 

disturbance size and recovery rate while at Stairs (near Point Conception), there was a 

positive relationship between initial disturbance size and recovery rate. 

• Recruitment was highly variable across sites and assemblages and had a non-linear 

relationship with recovery rate. 

• Community recovery was a strongly site-specific for all assemblages. 

STUDY PRODUCTS: 

Publications: 

June 2006: Contribution to Cabrillo Beach Aquarium quarterly newsletter Tidelines

“Disturbance and recovery of rocky seashores” Tish Conway-Cranos 
Spatial and Temporal Variation in Recruitment to Rocky Shores 

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Research Presentations:

March 2007: Pacific Ecology and Evolution Conference “Geographic variation in succession: 

Linking recovery rate, species interactions and recruitment” Tish Conway-Cranos 

June 2006: International Temperate Reef Symposium: “Geographical variation in recovery of 

intertidal communities following a disturbance: Linking recruitment to recovery” Tish 

Conway-Cranos 

November 2005: Western Society of Naturalists Conference “Geographical variation in 

recovery of intertidal communities following a disturbance: Linking recruitment to recovery” 

Tish Conway-Cranos 

Posters: 

March 2005: Monterey Bay National Marine Sanctuary Symposium “Geographical variation 

in recovery of rocky intertidal communities following a disturbance.” Tish Conway-Cranos