Rockweed Restoration | MARINe

Last updated Aug 23th, 2023

Introduction and Background

Rockweeds are often dominant algae in the mid to high intertidal zone, forming a broad, distinctive band. Canopy forming algae such as fucoids 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 rockweed communities could cause cascading negative effects to other species in this habitat. Furthermore, fucoids recover slowly without intervention (Conway-Cranos 2012). Juveniles do not disperse far from parent plants (Stekoll and Deysher 2000, Hays 2006, 2007) so restoration has been advocated as a strategy for compensation of anthropogenic impacts. UCSC is field testing methodology to efficiently and effectively lead to Fucus Restoration and Silvetia Restoration in disturbed areas.

Fucus Restoration 

Fucoids are highly sensitive to oil contamination (Reddin and Prendeville 1981) and Fucus was not considered fully recovered until over seven years following 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

A Fucus restoration plot in which indivuals are counted and measured in a circle radiating out from a central piece of rebar

Sampling Fucus along transect lines in East San Francisco Bay with rulers and small quadrats

Post Spill Fucus Restoration in San Francisco Bay

Fucus is a species that recovers slowly without intervention (Conway-Cranos 2012). 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which is what makes recovery of fucoid species very slow following a disturbance (Conway-Cranos and Raimondi 2009, unpublished data).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 methodology that will efficiently and effectively lead to recovery of Fucus in areas that were damaged by oil spills.

When a species has short range dispersal, 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 close to 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.

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:

1. Transplantation of adults
2. Reproduction by transplanted adults leading to recruitment at the restoration site
3. Small scale relocation of recruits to nearby areas within the restoration site to perpetuate increased cover

This project began in 2015. In 2016, it was considered recovered enough that human intervention was no longer implemented and the transplanted Fucus plants were left to further repopulate Point Isabel on their own.

In 2017, another site was established at Marina Park in San Leandro to increase the amount of area restored. Similar protocols were used as above (at Pt. Isabel) with minor modifictions. Sampling was conducted for one year. This site experienced much less success than Pt. Isabel.

• On October 30, 2009, the Dubai Star leaked over 400 gallons of Intermediate Fuel Oil while refueling

Another, smaller site at San Leandro Marina has been set up to mitgate damages done by the Dubai Star Oil Spill.

Silvetia Restoration 

Using proven restoration approaches combined with testing of novel alternatives, we are restoring impacted populations of Silvetia compressa across a broad geographic region of California (from San Diego to the Big Sur Coast, including the Channel Islands) to achieve stable and persistent rockweed populations that provide key ecosystem functions and benefits to rocky intertidal communities.

• See our StoryMap for more information

Questions? Please contact Laura Anderson (lmanders@ucsc.edu).

Laura installing a Fucus restoration plot

 

References

Bertness MD, Leonard GH, Levine JM, Schmidt PR, and Ingraham AO (1999) Testing the relative contribution of positive and negative interactions in rocky intertidal communities. Ecol 80:2711–2726

Bulleri F, Benedetti-Cecchi L, Acunto S, Cinelli F, and Hawkins SJ (2002) The influence of canopy algae on vertical patterns of distribution of low-shore assemblages on rocky coasts in the northwest Mediterranean. J Exper Mar Biol Ecol 267:89–106

Chapman AO (1990) Effects of grazing, canopy cover and substratum type on the abundances of common species of seaweeds inhabiting littoral fringe tidepools. Botanica Marina 33:319-326

Conway-Cranos LL (2012) Geographic variation in resilience: an experimental evaluation of four rocky intertidal assemblages. Mar Ecol Prog Ser 457:67-836. DeVogelaere AP and Foster MS (1994) Damage and recovery in intertidal Fucus gardneri assemblages following the ‘Exxon Valdez’ oil spill. Mar Ecol Prog Ser 106:263–271

Hays, CG (2006) Ecological consequences of dispersal and gene flow in an intertidal alga. University of California, Santa Cruz, CA

Hays, CG (2007) Adaptive phenotypic differentiation across the intertidal gradient in the alga Silvetia compressa. Ecol 88(1): 149–157

Reddin A and Prendeville GN (1981) Effect of oils on cell membrane permeability in Fucus serratus and Laminaria digitata/. Mar Poll Bull 12(10): 339-342

Stekoll MS and Deysher L (2000) Response of the dominant alga Fucus gardneri (Silva) (Phaeophyceae) to the Exxon Valdez Oil Spill and clean-up. Mar Poll Bull 40(11): 1028–1041

Wooton JT (1997) Estimates and tests of per capita interaction strength: diet, abundance, and impact of intertidally foraging birds. Ecol Monog 67:45-64