"How inappropriate to call this Planet Earth, when it is quite clearly Ocean." Arthur C. Clarke

"How inappropriate to call this Planet Earth, when it is quite clearly Ocean." Arthur C. Clarke

"How inappropriate to call this Planet Earth, when it is quite clearly Ocean." Arthur C. Clarke

"How inappropriate to call this Planet Earth, when it is quite clearly Ocean." Arthur C. Clarke



At the northern reaches of the Salish Sea, three unique marine reef ecosystems push into the rich mix of oceanic waters, where the flood tides rounding Vancouver Island meet.

The 3 Reefs boast a wealth of biodiversity; the marine food chains here spanning the spectrum  – from diatom to coastal wolf!

These spectacular rocky reef systems on the southern tips of Hernando Island, Cortes Island and Marina Island are the rebounded remains of 30 to 40 million year old ice age sediments originally depressed below sea level during the last glacial maximum. Sand and mud eroded away into the Strait of Georgia Basin, leaving behind boulders, cobbles and pebbles strewn over wave-cut terraces exposed only on the lowest tides of the year; true intertidal wilderness!

Our field observations are being compiled to prove that these reef systems are unique in coastal British Columbia, which is the prerequisite to qualifying them for marine protected area status.

The 3 Reefs are annually monitored for fauna & flora and ecosystem functioning. We have documented interstitial nurseries, harbour seal whelping grounds, seasonal concentrations of foraging shorebirds, midshipman spawning, coastal wolf foraging, critical feeding habitat for the great blue heron and wintering sea duck populations.

We have compiled the 3 Reefs Atlas to summarize our field observations to date. To view the atlas, click on the link or the book image, and select full screen option (click on the square in the right hand side lower corner).


Sabina Leader Mense and Nick Wunsch

We flew by helicopter at a lowest tide of the year to capture a seascape level view of the 3 Reefs, to provide context for our field observations. Our video footage, taken by Christian Gronau, was edited by Nick Wunsch, pictured here, a Youth Working for Nature participant from Quadra Island, and can be viewed here.

Vermetus, the worm snail

Interstitial space

Interstitial space — to Vermetus, the worm snail pictured here, is as vast as … outer space is to us!

Interstitial space is one of the key physical components of the 3 Reefs and describes the spaces between the sediments, which provide critical habitat for Vermetus and a diversity of other species of marine invertebrates, pictured below. The ecological significance of interstitial space is just beginning to be recognized.

SENSITIVE MARINE HABITATS – BC Coastal Seagrass Stewardship Project/Seagrass BC


Eelgrass, Zostera marina

Our locally occurring eelgrass, Zostera marina, is a seagrass. Seagrasses are used worldwide as indicators of nearshore health. Extensive, healthy meadows of eelgrass, are found along Cortes Island shorelines wherever the substrate is dominated by soft sediments.

Eelgrass plays critical roles in global climate and ocean cycles, provides vital nursery areas for many species, filters some coastal pollutants and slows shoreline erosion. Some of the most productive marine habitats are our eelgrass meadows, which feed directly, and indirectly, innumerable marine species.

Youth Working for Nature participants, Michaela Maxwell, Anna Ochsenbein and Camille Jones wrote an ecological report on eelgrass that covers the… who, what, where, when, why and wow of eelgrass biology! View their report here: E is for Eelgrass Ecological Report (PDF file), or flip through pages here: E Is for Eelgrass Ecological Report (for best viewing select full screen option: click on the square in the right hand side lower corner).

FOCI was partnered with the Seagrass Conservation Working Group (2002–2018), which had a membership of 19 coastal BC communities. In 2019, the Seagrass Conservation Working Group joined forces with the Hakai Institute to form Seagrass BC, which continues to coordinate eelgrass stewardship programs along coastal BC.

The original occurrence mapping of eelgrass in Cortes Island nearshore waters was digitized and incorporated into our regional level of government to advise coastal development.

FOCI monitors both intertidal and subtidal study sites. The Whaletown Bay subtidal study site provides an important baseline for future monitoring; check out the site map pictured here, Whaletown Bay Subtidal Study Site.

Whaletown Bay Subtidal Study Site

SENSITIVE MARINE HABITATS – Coastal Sand Ecosystem Project


Shark Spit, Cortes Island

Where sand is the dominant substrate for a community of terrestrial plants, you have a coastal sand ecosystem (CSE): beaches, dunes and spits. These areas are often associated with nearby forests, salt marshes and bluffs. Coastal sand ecosystems form at the interface between marine and terrestrial realms. They are built and maintained by marine-related natural processes: sand movement, wind and wave erosion, tides, storm surges and ocean spray

The majority of the BC coast is dominated by rocky shorelines, so that coastal sand ecosystems which occur only irregularly along the coast, represent a unique component. Coastal sand ecosystems are rare in BC, and correspondingly, the flora and fauna they support are also rare. Coastal sand ecosystems contribute to BC’s biodiversity. Coastal sand ecosystems support sparsely vegetated communities that have limited numbers of species that are characterized by distinctive adaptive properties to survive and thrive in the instability of sand!

Remnants of CSE are found on Cortes Island and nearby Marina Island (Shark Spit CSE pictured here), and each are associated with “feeder bluffs” of glacially deposited sediments lying to the south of their respective CSEs. Prevailing southwest wind waves in the Strait of Georgia set up longshore currents along the coastlines which transport sand to Smelt Bay, Manson’s Landing and Shark Spit.


Interpretative signage mounted on the Manson’s Landing Government Dock presented by BC Parks staff Erica McLaren (right) and Heather Steere (left).

FOCI has teamed up with BC Parks to study the coastal sand ecosystem at Manson’s Landing – read our Coastal Sand Ecosystem Community Outreach Report (pdf file) or flip pages (select full screen option for best viewing) here Coastal Sand Ecosystem Community Outreach Report; and check out the interpretative signage mounted on the Manson’s Landing Government Dock, pictured here with BC Parks staff Erica McLaren (right) and Heather Steere (left).



Youth Working for Nature participant, Shannon Hogan, initiated restoration of the Smelt Bay CSE in 2019 and designed her own interpretative signage for the site, pictured here. Check out Shannon’s great work next time you are walking or enjoying a beach fire, OUTSIDE the restoration area, on this section of the Smelt Bay shoreline!


Join the FOCI family

Become a Friends of Cortes Island member and support the work that we’re doing in the community to help look after our beautiful island.

Friends of Cortes Island Society (FOCI) is a charitable organization that has been active for over 25 years. Our organization exists to monitor and preserve the health of local ecosystems, and to provide educational programs that foster a greater understanding of the natural environment. Through all of our projects, we work to promote environmental integrity through community responsibility.