Shorekeeping on Semiahmoo Bay

Nuttall's Cockle

Since 2004, A Rocha has annually monitored a 50 m section of intertidal zone and backshore just east of the Little Campbell Estuary on Semiahmoo Bay, British Columbia. This study contributes data to the Shorekeeper’s programme run by the governmental agency Fisheries and Oceans Canada (DFO). It is a citizen science endeavour which aims to detect gradual changes in habitats and local biodiversity in the intertidal zone along the nation’s shorelines.

A Rocha has made a long-term commitment to shorekeeping at this site, which was chosen for its proximity to the estuary of the Little Campbell Watershed, the principal focus of conservation efforts for the team at the A Rocha Field Study Centre in Surrey. Besides the scientific aims of this annual effort, A Rocha’s goals include building relationship with community partners and DFO, and making connections with the local amateur naturalists who undertake the study at four other sites on Semiahmoo Bay. Participants submit data to DFO for compilation and the data is made available on www.keepersweb.org/Shorekeepers.

Sand Dollar

The intertidal zone at the Little Campbell Estuary site measures over 1200 m between highest high tide mark and the water at lowest low tide. Surveying requires two to three days a year and is undertaken in July, the only time when there are very low tides during daylight hours. Once mapped, each habitat is sampled with at least six systematically laid-out quadrats to observe the diversity and abundance of its flora and fauna. Quadrat size for the habitats of rock, cobble, Ulva, mixed algae and Zostera beds is 0.5 m2 and identification is done on the surface of the substrate and underneath moveable objects. In sand habitats, the quadrat size is 0.25 m2 and the substrate is removed to a depth of 10 cm and sifted.

Low tide at White Rock, Semiahmoo Bay

The site is rich in algae, molluscs and annelids. Over 70 organisms have been identified to species, and others to phylum or class. Annual differences recorded in the characteristics and areas of different habitats could be a result of physical changes to the substrate due to wind, tidal and freshwater currents or inconsistencies of recording, especially as the A Rocha survey teams have been different each year. This lack of continuity has compounded some of the inherent difficulties in habitat mapping over an area in excess of 40,000 m2 and in species identification where there is high biodiversity. From 2007 onwards, it is hoped to greatly improve the quality of the data by having a committed core team working together over consecutive years, each year recruiting and training new long-term participants.

In the meantime, another important goal of A Rocha’s investment in the Shorekeepers event is already being met: that of attracting members of the public, offering them a glimpse into the astonishing biodiversity of the intertidal zone and encouraging a deeper awareness of human influence over the health of this ecosystem.

Project leaders: Martyn Lings (2004), Glen Carlson (2005), Amanda Edworthy (2006)

Partners: Department of Fisheries and Oceans Canada, Friends of Semiahmoo Bay Society