University of Victoria (UV) - Dixon Island

Restoration Project

University of Victoria (UV) - Dixon Island

Restoration Objective:

To examine whether restoration outcomes can be enhanced by (1) sourcing and culturing kelp from the most local microclimate and (2) experimentally increasing the genetic diversity of cultured kelp by manipulating the number of parents used for propagation. Simultaneously, we tested the effectiveness of the “green gravel” restoration technique for outplanting Giant kelp (Macrocystis pyrifera sensu lato).

Site Selection Criteria:

Experimental areas were selected along sheltered coastlines at 3–7 m depth where canopy kelp historically occurred prior to the marine heatwave. Sites were located on gravel and cobble substrates to reduce sea urchin grazing and were adjacent to remnant Giant kelp populations. Bull kelp was absent at both sites, avoiding interactions with other canopy-forming species.

Cause Of Decline:

A prolonged marine heatwave that occurred in the Northeast Pacific Ocean between 2014 and 2016 (“The Blob”) (Rogers-Bennett & Catton 2019), including along the coast of British Columbia, caused a loss of the dominant canopy-forming kelp, Giant kelp (Macrocystis pyrifera) and Bull kelp (Nereocystis luetkeana), from 40% of sites along a 16 km gradient of Barkley Sound (Starko et al. 2022).

Key Reasons For Decline:

Heatwave

Organisation:

University of Victoria (UV)

Canada

Site Observations:

Observation Date

8th Mar 2023 – 28th Aug 2023

Action Summary:

Juvenile Giant kelp were cultured on green gravel in the laboratory and then outplanted into experimental plots on degraded reef to test restoration success across different parent sources and environments, with survivorship monitored over time.

Spores were collected from warm origin kelp populations, inoculated onto marble gravel with two parents and outplanted by SCUBA divers into 1 m² plots on gravel–cobble reef.

Lessons Learned:

Green gravel restoration success for Giant kelp is influenced by site conditions, with survivorship reduced by high grazer density and wave exposure, and growth enhanced at cooler, nutrient-rich sites.

Project Outcomes:

We successfully cultured and outplanted Giant kelp in British Columbia, performing an important first test of the green gravel technique that resulted in kelps growing holdfasts onto other rocks and some growing up to 5.3 m in length. Despite modest effects of source population, genetic diversity, and outplanting site on restoration outcomes, overall survivorship was low in all cases. The selection of kelp propagules from the most local site did not appear to enhance restoration success. In fact, kelp from the warm site sometimes showed signs of maladaptation. Although this study found only slight evidence for local adaptation between two geographically close sites, it revealed complex environmental drivers of kelp growth and survivorship. Kelp that originated from the cool site had moderately greater survivorship and growth overall, possibly because the source population had higher genetic diversity and may not have experienced a recent bottleneck. Kelp grew larger and faster at the exposed, colder site likely because of greater water movement and nutrient supply. Kelp survived best at the warmer, more sheltered site likely because there were fewer urchin grazers and less intense swell. Finally, although cultures resulting from only two parents survived better than cultures from 10 parents after 6 months in the field, we saw evidence of frequent self-fertilization in two-parent cultures we saw evidence of frequent self-fertilization in two-parent cultures, indicating negative consequences might be seen with greater statistical power or at later stages of the life cycle.

Area of Restoration (Ha)

0.0008

Indicator Data:

Indicator:

Ending Value:

Starting Value:

Percent Survival

1.8750
%
100.0000
%

Observation Date

8th Mar 2023 – 28th Aug 2023

Action Summary:

Juvenile Giant kelp were cultured on green gravel in the laboratory and then outplanted into experimental plots on degraded reef to test restoration success across different parent sources and environments, with survivorship monitored over time.

Spores were collected from warm origin kelp populations, inoculated onto marble gravel with ten parents and outplanted by SCUBA divers into 1 m² plots on gravel–cobble reef.

Lessons Learned:

Green gravel restoration success for Giant kelp is influenced by site conditions, with survivorship reduced by high grazer density and wave exposure, and growth enhanced at cooler, nutrient-rich sites.

Project Outcomes:

We successfully cultured and outplanted Giant kelp in British Columbia, performing an important first test of the green gravel technique that resulted in kelps growing holdfasts onto other rocks and some growing up to 5.3 m in length. Despite modest effects of source population, genetic diversity, and outplanting site on restoration outcomes, overall survivorship was low in all cases. The selection of kelp propagules from the most local site did not appear to enhance restoration success. In fact, kelp from the warm site sometimes showed signs of maladaptation. Although this study found only slight evidence for local adaptation between two geographically close sites, it revealed complex environmental drivers of kelp growth and survivorship. Kelp that originated from the cool site had moderately greater survivorship and growth overall, possibly because the source population had higher genetic diversity and may not have experienced a recent bottleneck. Kelp grew larger and faster at the exposed, colder site likely because of greater water movement and nutrient supply. Kelp survived best at the warmer, more sheltered site likely because there were fewer urchin grazers and less intense swell. Finally, although cultures resulting from only two parents survived better than cultures from 10 parents after 6 months in the field, we saw evidence of frequent self-fertilization in two-parent cultures we saw evidence of frequent self-fertilization in two-parent cultures, indicating negative consequences might be seen with greater statistical power or at later stages of the life cycle.

Area of Restoration (Ha)

0.0008

Indicator Data:

Indicator:

Ending Value:

Starting Value:

Percent Survival

1.2500
%
100.0000
%

Observation Date

8th Mar 2023 – 28th Aug 2023

Action Summary:

Juvenile Giant kelp were cultured on green gravel in the laboratory and then outplanted into experimental plots on degraded reef to test restoration success across different parent sources and environments, with survivorship monitored over time.

Spores were collected from cold origin kelp populations, inoculated onto marble gravel with two parents and outplanted by SCUBA divers into 1 m² plots on gravel–cobble reef.

Lessons Learned:

Green gravel restoration success for Giant kelp is influenced by site conditions, with survivorship reduced by high grazer density and wave exposure, and growth enhanced at cooler, nutrient-rich sites.

Project Outcomes:

We successfully cultured and outplanted Giant kelp in British Columbia, performing an important first test of the green gravel technique that resulted in kelps growing holdfasts onto other rocks and some growing up to 5.3 m in length. Despite modest effects of source population, genetic diversity, and outplanting site on restoration outcomes, overall survivorship was low in all cases. The selection of kelp propagules from the most local site did not appear to enhance restoration success. In fact, kelp from the warm site sometimes showed signs of maladaptation. Although this study found only slight evidence for local adaptation between two geographically close sites, it revealed complex environmental drivers of kelp growth and survivorship. Kelp that originated from the cool site had moderately greater survivorship and growth overall, possibly because the source population had higher genetic diversity and may not have experienced a recent bottleneck. Kelp grew larger and faster at the exposed, colder site likely because of greater water movement and nutrient supply. Kelp survived best at the warmer, more sheltered site likely because there were fewer urchin grazers and less intense swell. Finally, although cultures resulting from only two parents survived better than cultures from 10 parents after 6 months in the field, we saw evidence of frequent self-fertilization in two-parent cultures we saw evidence of frequent self-fertilization in two-parent cultures, indicating negative consequences might be seen with greater statistical power or at later stages of the life cycle.

Area of Restoration (Ha)

0.0008

Indicator Data:

Indicator:

Ending Value:

Starting Value:

Percent Survival

3.7500
%
100.0000
%

Observation Date

8th Mar 2023 – 28th Aug 2023

Action Summary:

Juvenile Giant kelp were cultured on green gravel in the laboratory and then outplanted into experimental plots on degraded reef to test restoration success across different parent sources and environments, with survivorship monitored over time.

Spores were collected from cold origin kelp populations, inoculated onto marble gravel with ten parents and outplanted by SCUBA divers into 1 m² plots on gravel–cobble reef.

Lessons Learned:

Green gravel restoration success for Giant kelp is influenced by site conditions, with survivorship reduced by high grazer density and wave exposure, and growth enhanced at cooler, nutrient-rich sites.

Project Outcomes:

We successfully cultured and outplanted Giant kelp in British Columbia, performing an important first test of the green gravel technique that resulted in kelps growing holdfasts onto other rocks and some growing up to 5.3 m in length. Despite modest effects of source population, genetic diversity, and outplanting site on restoration outcomes, overall survivorship was low in all cases. The selection of kelp propagules from the most local site did not appear to enhance restoration success. In fact, kelp from the warm site sometimes showed signs of maladaptation. Although this study found only slight evidence for local adaptation between two geographically close sites, it revealed complex environmental drivers of kelp growth and survivorship. Kelp that originated from the cool site had moderately greater survivorship and growth overall, possibly because the source population had higher genetic diversity and may not have experienced a recent bottleneck. Kelp grew larger and faster at the exposed, colder site likely because of greater water movement and nutrient supply. Kelp survived best at the warmer, more sheltered site likely because there were fewer urchin grazers and less intense swell. Finally, although cultures resulting from only two parents survived better than cultures from 10 parents after 6 months in the field, we saw evidence of frequent self-fertilization in two-parent cultures we saw evidence of frequent self-fertilization in two-parent cultures, indicating negative consequences might be seen with greater statistical power or at later stages of the life cycle.

Area of Restoration (Ha)

0.0008

Indicator Data:

Indicator:

Ending Value:

Starting Value:

Percent Survival

0.6250
%
100.0000
%
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