Joint trip with Wonders of the Salish Sea & Nature Vancouver

Report by Sheila Byers, Member of Nature Vancouver & Wonders of the Salish Sea

What a day of intertidal exploring we had on Saturday, May 6, 2023! Spring tide low water level (LLW): 13:13 at 0.6 m elevation. The forecasted rain was just a sprinkle making our trip quite comfortable, albeit cool under an overcast sky. Fifteen participants arrived early at 12:15 to the Lumberman’s Arch area to sign the Liability Waiver forms. Keeners from both Wonders of the Salish Sea and Nature Vancouver attended. Three hours later, the hangers-on begrudgingly departed at 15:30!

The unique combination of leaders provided a wonderful holistic approach to intertidal exploration: Wonders of the Salish Sea (WSS)—trip coordinator and fearless leader Deborah Simpson; Nature Vancouver Marine Biology Section—Marine Biologists and experienced field guides Sheila Byers and Joan Lopez; and special invited guest and seaweed guru—Dr. Bridgette Clarkston, UBC Professor.

Our destination goal: the large boulder area off Figurehead Point before the tide changed direction. First on the agenda: resolve the WSS Chat question noted in the April 3 WSS program presentation: At a beach that you often frequent, if you stood in the middle of the intertidal area at high tide, would your head be above or below the water? Answer: we stood in the sandy mid-intertidal beach looking southward towards the north-facing rock seawall. In Stanley Park, the gradual slope of the intertidal towards the forested upland is shortened by the hardened edge of the seawall. Nonetheless, the seawall provides habitat for marine life adapted to the upper intertidal, covered during the high tide. Even with height variation of participants, a high tide would cover our heads. In this somewhat protected bay, the slope of the beach is quite gentle. Would the result be the same on a steeply sloped beach on the west coast of Vancouver Island? 

Within a short distance, we were attracted to a distinct growth of green seaweed that fanned out from the outflow of an upland stormwater pipe draining into the mid-intertidal area. Brigette identified a species of green sea lettuce, cornrow or sea hair sea lettuce (Ulva intestinalis). This tubular seaweed, often associated with freshwater seepages, is the most common species found growing on rock all over the world (cosmopolitan species). 

Near the low water edge of the sandy beach a half-buried rock presented an array of large seaweeds. Bridgette took the opportunity to introduce the three major groups of seaweed categorized by colour: the greens, reds and browns. It seems straight-forward, but interpreting colours can be tricky especially between the reds and browns.      

The cornrow sea lettuce noted earlier was an example of green seaweed, a colour we generally associate with land plants. Green seaweeds have chloroplasts that contain the green pigment, chlorophyll. Chlorophyll captures the energy of the sun that is necessary for photosynthesis. It was a green seaweed that some 400 million years ago, ‘invaded’ land and evolved into our land plants.

A large specimen of Turkish towel (Chondracanthus exasperatus) provided an example of red seaweed. Red seaweed contains the phycoerythrin pigment but seaweed colour can vary from deep wine reds to purplish pink. Dark red variations, in particular, can present difficulties distinguishing dark brown seaweed. Note the bumpy surface (papillae) of the towel that gives the seaweed its rough texture and human interest to use this ‘towel’ as a handy skin scrub.

Bridgette was surprised to see so many young bull kelp (Nereocystis luetkeana) attached to the rocks in the intertidal sandy area. Bull kelp are a good example of brown seaweed, that with the presence of the fucoxanthin pigment, can vary in colour from yellow/light brown to dark brown. Less than a metre in length and located in the mid to lower intertidal zone, she predicted that the young subtidal kelp would not survive long there due to the lengthy low tide exposure to the sun and heat. Capable of growing to great lengths of 10-35 m annually, the bull kelp is adapted to subtidal depths with a single float that keeps the blades near the surface for photosynthesis. 

The young bull kelp provided ideal specimens from which to describe the holdfast, stipe, float, and blades. The tips of the blades are where the reproductive patches of spores (sori) are produced. Bull kelp is an annual seaweed. Imagine this kelp growing to such lengths in just 6-7 months!!

Kelp is a term used to describe the large brown seaweed. 

As we progressed towards the rocky Figurehead Point, we were overwhelmed by the extensive expanse of brown kelp including bull kelp, sugar wrack (Saccharina latissima) and the broad-winged kelp (Alaria marginata). Bridgette reminded us that all kelp is seaweed but not all seaweed is kelp!

Along the way to the point, two unusual red species were discovered, although neither was attached. One, a delicate pale red, flat blade with a conspicuous midrib and feathery side branches is known as the winged rib, (Cumathamnion decipiens). Curiously, it is so fragile that if mishandled (becomes too warm), it will bleed its red pigment! The second, a flattened and tough, thick-bladed bleach weed (Prionitis sternbergii) releases a bleach-like smell when squished that is thought to be a chemical defense against grazers. The latter species is not unlike the acid weeds with regards to the production and use of chemicals (sulfuric acid). The sulfuric acid stored in the acid weeds will digest anything with which it comes in contact!! Both of these algae are found in the lower intertidal area and a first record for many of us frequenting the Figurehead Point area. 

A much smaller brown seaweed looked like well-used paper straws: unbranched hollow tubes that had constrictions at more-or-less regular intervals. This golden-brown seaweed is known as the soda straw (Scytosiphon lomentaria). The soda straw is a strong contrast to the multi-branching red seaweed attached to the shell. The latter red spaghetti seaweed is a Gracilaria species that is part of a complex of difficult species to identify. As Druehl and Clarkston state of Gracilaria in their 2016 book, the complex of species appears to be distinguished by a lack of distinguishing features – at least, none that are morphological (describing the form of living organisms). So much to learn!!

The seaweed growing at Figurehead Point is beautiful, bountiful and astounding. And this diversity is reinforcing, given its location within the busy industrial harbour of Burrard Inlet. Thankfully, the inlet is not the polluted harbour of its historical past.

But WAIT! What about marine invertebrates?!?!?! Normally when Joan and/or I lead intertidal explorations, we focus primarily on the diverse intertidal invertebrates.  

An important news report is that a good number of purple or ochre sea stars (Pisaster ochraceous) continue to be found hunkered down under the north-facing base of many of the large boulders. A few unhealthy-looking individuals were found ‘out in the open’. Was this a sign that the sea star wasting disease syndrome was still present; or did these few individuals succumb to the persistent pecking of the hungry sea gulls and crows? Considering the health of the majority of the purple stars it was likely the latter. Healthy looking leather stars and mottled stars were also found, evidence of a promising recovery of these species of sea stars. However, the survival and recovery of the affected sunflower star (Pycnopodia helianthoides) remains uncertain

Apart from the usual butter clams, fat gapers and heart cockles, an obvious increase in the abundance of the introduced Pacific oyster (Magalana gigas) was very noticeable this year! Is this because they are better adapted and more at home in the warmer water brought by climate change? Also, however, the abundance of the native frilled dogwinkle (Nucella lamellosa) seemed to increase over observations of previous years. It is tempting to consider that the predatory dogwinkle may prove beneficial as a natural control of the prolific oysters. 

Someone’s sharp eyes saw a very cool and rare-to-find cluster of tiny yellowish, donut-shaped egg sacs. These distinctive shaped egg sacs were likely deposited by the wide lacuna, Lacuna vincta.  Obviously, the early spring is the time not only for growth of algae but for lots of reproductive action for the intertidal flora and fauna!

It is not just large marine life that live in these productive intertidal areas. There are many smaller organisms that hide beneath the seaweed or under rocks. A scale worm (bristleworm or polychaete) was found with its paired scale-like elytra clearly overlapping and covering its back. Even a green urchin, (Strongylocentrotus droebachiensis) was located under a flat rock. Its larger size indicates a good feeding supply relative to the smaller sizes (~1 cm) observed last year. Alternatively, it’s growth could be a direct result of the demise its a major predator, the sunflower star, normally found off Figurehead Point.

To the delight of everyone, another overturned rock revealed a fish trying to hide and keep moist through the low tide period. The frightened, wiggling fish had a broad orange/red tail fin and the rest of the body also appeared red. But other defining markings were more difficult to observe. My attempt to identify the fish landed on the Red Gunnel (Pholis schultzi). In retrospect and in reviewing the description and image of this fish, I am less confident with this identification. I now wonder if it might be a longfin gunnel (Pholis clemensi). Such arises the problem with using only colours for species identification. Since I am not a fish specialist, I am afraid that the name of the mystery fish remains unknown. Perhaps another visit to Figurehead Point is necessary, accompanied by an ichthyologist, to clarify the identity of this illusive fish.

All in all, a rich diversity of organisms was found during the field trip to the sandy beach and rocky Figurehead Point area of Stanley Park. The low spring tides are such an excellent time to explore any intertidal area and we were not disappointed. The combined focus on algae and marine invertebrates made for a very informative and interesting day. With all the foot traffic that this Stanley Park beach gets throughout the year, I continue to be amazed at the survival resiliency of its biodiversity.

Thank you to all the contributors, photographers and enthusiastic participants. 

Resources:

• Andy Lamb and Phil Edgell. 2010. Coastal Fishes of the Pacific Northwest. Revised and Expanded Second Edition. 
• Louis D. Druehl and Bridgette E. Clarkston. 2016. Pacific Seaweeds. A Guide to Common Seaweeds of the West Coast. Updated and Expanded Edition.
• Mandy R. Lindeberg and Sandra C. Lindstrom. 2010. Field Guide to Seaweeds of Alaska. Alaska Sea Grant
• Sandra C. Lindstrom. Brochure
• Wonders of the Salish Sea Programs: https://wondersofthesalishsea.com/