Roughly twenty shoreline members made it out on Wednesday to investigate 12,500 year old sand deposits laid down 10m below sea level back when the the waves would have been lapping at the spot where today you find the front entrance of the Home Depot at Lerwick & Ryan roads. We collected quite a few shells from a number of mollusc species (see annotated photograph below) and looked at a brief window of the local Pleistocene sediments. To follow up on some of the things we were curious about, there are some notes, diagrams and photographs below.
What did we find?
We found 12,500 shell deposits that showed a diversity of sizes and shapes indicative of a natural concentration of shell material driven by water currents. In the 250ml plastic container of shells, we had the following
Barnacles (Balanus sp.)
Tubeworms (Serpula vermicularis)
Scallops (Chlamys sp.)
Limpet (Acmaea sp.)– with bore hole from (?) gastropod radula
Mussels (Mytilus sp.)
Butter Clam (Saxidomus giganteus)
Echinoderm spines (see pictures– in the fine sediments)
Echinoderm spine (rod-shaped fragment among 1/2mm sand grains.
What is the sequence of unconsolidated sediments in our area and how old are they?
The shells, bones & wood excavated from the site give a corrected age of around 12,5000 years based on radiocarbon dating. We were digging through the “Capilano” and/or “Salish Sediments”, layers that were deposited along the sea floor (and shore) after the ice had retreated. Looked down an excavated face in the quarry and saw poorly-layered glacial till (“Vashon Drift”) beneath (material melted out of the ice sheet). This in turn would be underlain by stratified sand and clays of the Quadra Sands, which were deposited by waters running off the leading edge of the ice sheet as it retreated and advanced sometime between 20-30,000 years ago. The Quadra Sands are the sediments that make up most of the Willemar Bluffs in Cmox as well as the cliffs around Seal Bay, Denman Island and Quadra Island. I am pasting below a chart showing the ages, composition and sequence of major layers of sediment in our region from Jan Bednarski’s (Geological Survey of Canada) 2015 report on surficial deposits just south of Deep Bay.
John was remarking on how well-preserved the shells are given their age and how porous the sediments were. These shells would be subject to all the chemical weathering that the pore waters could bring about. Perhaps the density of shell material acted as a buffer to keep acids from leaching away too much of the material. As many of you saw, some of the mussels still had a hint of nacre left on them, meaning that the organic matter has not completely broken down, either.
These types of materials are broadly referred to as sub-fossils. True fossils are old and encased in consolidated sediments. Really it doesn’t matter– these are evidence of ancient life in our region just around the time that we start to see physical evidence for human habitation in our region. The assemblage of shells is interpreted to represent a cold water community akin to what would be seen around 60 degrees north today.
CVN invites the public to learn about the Salish Sea Nearshore Habitat Recovery Project
Comox Valley Nature is pleased to host a public lecture. Join Ann Eriksson for an illustrated talk entitled: “Salish Sea Nearshore Habitat Recovery Project (SSNHRP)”. The lecture is on Sunday March 17, 2019 and will start after introductions at 7pm in the Rotary Room of the Filberg Seniors Centre 411 Anderton Ave, Courtenay.
Recovery of native eelgrass (Zostera marina) habitats. Photo by Ann Eriksson
SeaChange Marine Conservation Society is a not for profit marine conservation organization based in Brentwood Bay, BC. Since 1998 SeaChange has focused on conservation and restoration of marine life in the Salish Sea, primarily through education and the recovery of native eelgrass (Zostera marina) habitats. In 2017, SeaChange was granted funding support from the Coastal Restoration Fund through the Department of Fisheries and Oceans for a five year project, the Salish Sea Nearshore Habitat Recovery Project (2017-2022). Now in Year 2, the goal of this project is to recover ecosystem health and increase resiliency of nearshore marine intertidal and subtidal habitats for all species of salmon and the critical forage fish upon which they depend and are most affected by anthropogenic activities. Activities include removal of underwater debris to expand potential eelgrass habitat, restoration of damaged, degraded or destroyed eelgrass habitats, and improvement of marine riparian areas where feasible in sites utilized by juvenile salmon and spawning forage fish. This regional approach is possible because of successful long-term partnerships with local First Nations, BC Parks, other community and stewardship groups, local businesses, and Fisheries and Oceans Canada. Come and hear about progress of the project and how you can get involved.
Biologist and author Ann Eriksson is the SSNHRP Technical Coordinator for the Gulf Island Region. Ann lives on Thetis Island and is a founding director of the Thetis Island Nature Conservancy. Her most recent book, Dive In! Exploring Our Connection with the Ocean is a non-fiction title for children about ocean conservation.
This is an excellent opportunity for the public to learn more about the Salish Sea Nearshore Habitat Recovery Project.
Comox Valley Nature is a non-profit society affiliated with BC Nature, consisting only of unpaid volunteers. CVN fulfills its educational mandate by hosting monthly lectures, organizing free weekly guided hikes for members, and a free monthly walk open to the public. Comox Valley Nature also supports specialized groups (Birding, Botany, Marine & Shoreline, Conservation, Garry Oak Restoration, Wetland Restoration, Photography and Young Naturalists Club) which have separate monthly activities. Membership in BC Nature and Comox Valley Nature is $30.
Founded in 1966, it is one of the oldest environmental societies on the North Island. Meetings and lectures of the Comox Valley Naturalists Society are held on the third Sunday of most months at the Florence Filberg Centre, 411 Anderton Ave., Courtenay. Meetings and guided walks are open to the public, including children and youth. Lecture is free, though a $4 contribution from non-members is appreciated. New memberships are always welcomed.
Anyone interested in this lecture or participating in CVNS activities can also contact us at the website http://comoxvalleynaturalist.bc.ca/
Between the Botany group and the Shoreline group, we had a big turnout on a lovely late winter day. Conditions were so great, in fact, that we were hardly bothered by the lack of seaweeds that were supposed to be the focus of the day. Betty was giving demonstrations on how to press seaweeds, replete with finished examples of lovely red algae and miniature bull kelp, among others.
A few notes:
- A seaweed reading and resource list is attached as a PDF. I intended to hand this out with a little preamble about what to be on the lookout for, but didn’t want to interrupt a pleasant lunch.
- Sharon N. followed up on a question about whether any seaweeds could be used for dying of fibres. She passed along a paper that used a green algae from Malaysia as a natural source for green coloration of textiles using boiling water and “ammonia-fermentation”. I’m sure Sharon would agree that there would be a lot of interest in a local seaweed that could be used as a dye.
- There was talk about using seaweed as fertilizer and food. Sharon also kicked up this old DFO report on uses of marine plants. Forgive the antiquated language, but I paste an excerpt from the publication below to catch the attention of those who might be excited at the thought of making beverages, knife blades or insulating materials from local seaweeds. This old (1961) publication has a short discussion of impacts of seaweed harvesting
“There is a variety of uses of algae that can be recorded in connection with human activities. Rhodymenia palmata is used in Kamchatka to prepare a strong alcoholic drink. The Alaskan Indians and Eskimos are reported to make a brew called hoochenoo from Nereocystis. Methods have been proposed for the manufacture of manna-like substances from certain species of Laminaria containing a considerable amount of sugar and mannitol. A candied peel and pickles have been prepared from the fleshy stipe of Nereocystis”.
- On the fertilizer front, Roger and Betty were talking about the use of dead, fermenting piles of seaweed on their garden. VIU’s Marine Field Station down in Deep Bay did a study on the utility, logistics and impacts of seaweed piles as a fertilizer. Of interest to our group– they monitored when the largest volume of seaweed washed up. We will plant out outing for late October next year (see chart below of shore seaweed biomass v. calendar date)
- There was a lot of interest in the flatworms. There are lots of interesting things about flatworms. This video shows a high-resolution sequence of their regenerative ability. Lastly, no mention of flatworms would be complete without mention of their famous “Penis Fencing”. You can chose to watch this video or not, but be assured it is very biological and very interesting.
- Crustose seaweeds. We saw a dark “tar spot” that I was erroneously referring to as Ralfsia-like. While some of these dark spots may have been that tar-spot genus, others showed young Turkish washcloth (Mastocarpus) emerging. There was also a lively, red crust.
- Jocie snagged a thin, brown-green filamentous seaweed that at first blush looked like cyanobacteria. How do you distinguish between uniseriate (single-cell thick) seaweeds and cyanobacteria? Broadly speaking, algae are relatively more robust (they can take more tensile stress). Under the microscope, the difference is much clearer. Cyanobacteria, by virtue of being prokaryotic organisms, have no membrane bound organelles. A simple stain shows nuclei if you have a true alga. The little mucky looking seaweed that Jocie saw turns out to be a brown alga. Sea felt.
- Some seaweeds have remarkably complex life histories. We saw some encrusting phases and some leafy phases of red alga. We saw young sea lettuce, which alternate between haploid (gametophyte) and diploid (sporophyte) that are morphologically and functionally identical . The preceding links show lovely life cycles.
- What did we see?
- Rockweed (Fucus)
- Sea Lettuce (Ulva)
- Black pine (Neorhodomela)
- “Laver”/Sushi Seaweed (Porphyra)
- Turkish towel (Chondracanthus)
- Turkish Washcloth (Mastocarpus)
- Sea Lace (Microcladia)
- Sea felt (Pylaiella)
- Rusty rock (Hildenbrandia)
- Unidentified tubular species.
- Lastly– the peaks in the distance to the north and east. Peakfinder is a handy website and app for making sense of landscapes. According to that site, the Matterhorn-like peak was Mt. Denman, and the tall peak to the left was Mt. Doogie Dowler.
Thanks again to Betty for hosting and demonstrating and sharing all of her
See you soon, Randal
Here is my take on last night’s wonderful outing at Miracle Beach
Thirteen naturalists caught a break in the weather to survey the sand flats of Miracle Beach Provincial Park. Under the light of a full moon, the group lamped up to catch the 10:30 pm low tide. Some of the highlights from the outing included
Moonsnails (Neverita lewisii)
· Pipefish (Syngnathus leptorhynchus)
· Leather Stars (Dermasterias imbricata)
· Purple Sea Star (Pisaster ochreus)
· Kelp Crabs (Pugettia sp.)
· Decorator crabs (Oregonia gracillis)
· Aeloid Nudibranch (Hematina trophina ?)
· Sand anemone (species uncertain)
· Eccentric Sand Dollars (Dendraster eccentric)
· Large hermit crabs (Pagarus sp.)
· Horse Clams/Gapers (Tresus sp.)
· Nuttall’s Cockle (Clinocardium nuttallii)
· Whelk shells (occupied by hermit crabs)
· Tube worm casings galore
There were a few remarkable things we saw in the throughs between sand bars. There was a remarkable density of oblique-to-vertically-oriented sand dollars. I counted more than 100 in a 1 m2 at my feet and then got tired of counting. This video from the California Academy of Sciences gets into the physics of their orientation and morphology as it related to feeding and currents and might be of interest to those who were taken with their orientation & form.
Ian pointed out that he has noticed pipefish around pilings and amongst eelgrass beds whilst kayaking. We found them in groups loitering casually in sandy depressions. What were they doing just hanging out here? These relatives of the seahorse feed on crustaceans (maybe the small translucent-brown shrimp or copepods?). Like the seahorses, the males hold the eggs during development. We didn’t notice any brood pouches. Maybe we caught them just being pipefish, living around the eelgrass and feeding on little shrimp.
We saw one unhappy moonsnail with a semi-retracted foot, while Diane found a vigorous specimen cruising the low-tide line looking for some mollusk to murder. Ian and Betty clarified that the moonsnails are vicious predators, using their muscular foot and abrasive radular to drill holes through the shells of bivalves and gastropods so that they may feed on the soft tissues within. This website by Tom Carefoot digs into the research about the mechanics and efficacy of moonsnail feeding.
A seaslug of uncertain affinities
Forgive the lack of photographs, but it was dark. Near the end, we saw a translucent white nudibranch with reddish-pink cerata (fleshy/hairy outgrowths along the back) that terminated in a creamy yellow bulb. If anyone has a confident ID of this, let us know. The keys pointed towards Hematina (Flabellina) trophina, but at that point they were using the flange of the vas deferens as an identifying character. Never the less, the broader group “Aeolids” in this environment have an interesting feeding feature. All over the beach were tubeworm sheaths. It turns out species in this group feed on hydroids (like Obelia) that grow on the outer surface of these tubeworm casings.
It was informally resolved that we try a late summer evening outing to catch bioluminescence in action. Another winter low tide outing will be planned for next year.
Betty Brooks has invited botany and shoreline group members over in February to look into a demonstration of seaweed pressing and survey the tatters of seaweeds onshore in the late winter. Exact details will be mailed out soon.