Pacific Rocky Intertidal Monitoring: Trends and Synthesis
Last updated November 18th, 2016
Introduction and Background
Fucus is often a dominant alga in the mid to high intertidal zone, forming a broad, distinctive band. Canopy forming algae such as Fucus provide food (Chapman 1990, Wooton 1997) and shelter to myriad other organisms (Bertness et al. 1999, Bulleri et al. 2002). Altering rocky shores by damaging Fucus communities could cause cascading negative effects to other species in rocky intertidal habitats.
A Fucus restoration plot in which indivuals are counted and measured in a circle radiating out from a central piece of rebar
Fucoids are highly sensitive to oil contamination (Reddin and Prendeville 1981) and heat, as demonstrated by increased Fucus mortality in hot water cleaned areas versus un-treated rocks following the Exxon Valdez oil spill in 1989 (DeVogelaere and Foster 1994). Fucus was not considered fully recovered until over seven years after the Exxon Valdez spill (Driskell et al. 2001).
- On November 7, 2007, the Cosco Busan freighter hit the San Francisco Bay Bridge and spilled 53,569 gallons of Intermediate Fuel Oil (Cosco Busan Oil Spill Trustees 2012)
- Intertidal researchers from UCSC conducted post-spill monitoring and found that Fucus distichus populations declined throughout the East San Francisco Bay
Sampling Fucus along transect lines in East San Francisco Bay with rulers and small quadrats
Post Spill Restoration in San Francisco Bay
Fucus is a species that recovers slowly without intervention (Conway-Cranos 2012). Fucoids exhibit an "animal-like" gametic/diplontic life history: thalli are diploid and gametes are formed via meiosis (Searles 1980). Sperm and eggs are produced within blades of individuals and gametes mix when exuded at low tide. Eggs are fertilized with the incoming tide, and the resulting zygotes secrete adhesive and attach themselves to the substratum (O’Clair and Lindstrom 2000). Juveniles do not disperse far from parent plants (Stekoll and Deysher 2000, Hays 2006, 2007) which is what makes recovery of fucoid species very slow following a disturbance (Conway-Cranos and Raimondi 2009, unpublished data). Because natural recovery is slow, restoration has been advocated as a strategy for compensation of anthropogenic impacts. As adults, fucoids can be transplanted successfully; therefore, the goal of UCSC's Fucus Restoration project is to field test a methodology that will efficiently and effectively lead to recovery of Fucus in areas that were damaged by the Cosco Busan oil spill.
When a species has short range dispersal and no other mode of regular dispersal of adults (e.g. floating rafts), there is always the possibility of very local genetic structure. This becomes important when deciding on potential donor populations. UCSC did genetic work before conducting restoration and found limited spatial genetic structure within San Francisco Bay; however, it was mostly partitioned in clusters. This suggested that donor populations could be identified (as nearby recipient sites as possible) that would not disrupt local structure or adaptation. UCSC researchers selected Golden Gate Fields, where many Fucus individuals remain, as a source population for transplanting adults to Point Isabel Regional Shoreline, where the Fucus population was negatively impacted by the Cosco Busan spill and high powered hot water clean up.
A cluster analysis in which the same colored circles indicate fucoid populations with corresponding genetic structure while unique colors represent populations with dissimilar genetic makeup
One issue concerning restoration of marine habitats is how to provide donor species to impacted areas without compromising the ecological or structural integrity of donor patches. A way to avoid excess depletion of adults is to use propagules to replenish depleted populations (propagules are often small, mobile, and prolific). This approach to restoration at Point Isabel combines an understanding of the life history of Fucus with the goal of minimum impact to donor populations. The approach we are testing is to use limited donor adults to “seed” the restoration site. The key attribute to be assessed is the relationship between the number of adults and the production/dispersal distance of resultant juveniles. This is a three-step process:
- Transplantation of adults
- Reproduction by transplanted adults leading to recruitment at the restoration site
- Small scale relocation of recruits to nearby areas within the restoration site to perpetuate increased cover
Questions? Please contact Laura Anderson
Laura installing a Fucus restoration plot
ReferencesReferences not listed here can be found under target species references
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