Gowlland Point, South Pender
Area, South Pender Island
Low rock/boulder shore types are a mix of hard bedrock ramps and
boulder beaches that have a slope of less than 20%. These
low-slope, mixed rock and boulder shores are a common shore type on
the Gulf Islands.
The low rock/ boulder shore type is almost 51% of the total
shoreline in the Islands Trust area based on the twelve major
islands that had shoreline mapping completed. Mayne Island
has the most at 66%, while Gambier Island has the least at
31%. 59% of South Pender Island's shoreline has been
mapped as the low rock/ boulder shore type.
The low rock/boulder shores are a mixture of sediment and rock,
and are moderately resistant to erosion. They tend to have a
limited sediment supply and be stable over a human time scale.
Sediment transport processes depend on the wave energy at the site,
with more exposed shores having some onshore/offshore and longshore
transport. Low rock/boulder shores often have driftwood
accumulations in high intertidal and backshore areas.
The biodiversity at low rock/boulder shore types depends on the
wave exposure and sediment mobility. Higher energy sites will have
bare, mobile boulders and attached biota on rock platforms.
Moderate energy shores that are more stable can have lush attached
communities, including many invertebrate species which live in
microhabitats under boulders.
Like sea cliffs, the common upper intertidal zone community
includes barnacles, rockweed and blue mussels on stable substrates.
Diversity in the lower intertidal zone depends on wave exposures,
with moderate or high exposures usually having more species than
protected shores. Common species include benthic kelps, several
species of red algae, and numerous invertebrates such as sea stars,
crabs, anemones and others. Bull kelp often is found on immobile
Backshore and riparian vegetation can be a major contributor to
slope stability along the high water line, where established root
mats help to reduce soil erosion.
Shallow nearshore areas of these shallow sloped rock/boulder
shores are important foraging areas for overwinter sea ducks and