Dungeness Crab Larvae Monitoring in the Cowichan Estuary
Citizen Science in the Cowichan Valley
a contribution by CERCA member Steve Nazar
"Scientist" is a rather new job description, historically. The word was only coined in 1833. It now suggests a researcher on staff with a university, government, or major company. These are elite job positions, usually requiring greater than ten years of intense study beyond highschool. But this was not always the way Science was done. Isaac Newton, Benjamin Franklin, Charles Darwin and even Einstein in his earlier years were just thoughtful, educated individuals with an interest in the world. Grant committees were not involved! Today we might call these "citizen scientists".
We need more citizen scientists. Particularly at the interface of ecology and resource management, our understanding is so rudimentary that potentially any of us can ask new questions. All of us can help with the necessary observations.
There is certainly also need for highly schooled and trained individuals with labs full of expensive equipment…. but there is also a need for all the rest of us to actively learn, look and think about what we see. With a little guidance we as volunteers can help gather the data that would otherwise be so expensive in labor costs.
CERCA is practising citizen science. At the Cowichan Estuary, two major rivers join at the Pacific sea… and here also human population and industries have gathered. Within living memory of the less populated past, the Estuary was far more productive of fish and shellfish. CERCA's mission is the restoration and conservation of the Cowichan Estuary, thus the acronym.
CERCA seeks to understand the estuary and its functions in our Island ecology. Only if we understand the workings and the changes can we plan what must be done to move the estuary toward greater health. CERCA has ongoing programs in collaboration with universities and the Federal government as part of Masters and PhD programs. These have been remarkably productive but are distinct from CERCA's participation in "citizen science" projects.
CERCA recognizes we must start early to make either scientists, or citizen scientists. If many kids can be exposed to the systematic study of Nature, maybe a few will go into the formal Sciences as a career -- but the greater number of citizen scientists may be more important. As adults they have votes, and can therefore influence the political awareness of ecological issues that we so greatly need. With this in mind, CERCA has been training local high school students in citizen science, as part of the school curriculum. The collaboration with the schools has continued for six years.
In charge of the High School collaboration are Dr. Bill Heath, a marine biologist and CERCA's Co-Chair, and Dr. Goetz Schuerholz, CERCA's Chair and founder of the organization.
On May 25, 2022 I went along on a sampling session with Bill and Goetz, and a group of high-schoolers. The group were mostly from a split Grad10/Grade 11 class. They had been offered a number of choices for their "Outdoor Time" in their curriculum. These particular kids had chosen to work with Bill and Goetz as "interns" on CERCA projects, one of them a new citizen science project, a crab larvae census. The interns proved to be a serious and attentive group, eager to help.
The larvae we sought were those from Dungeness crabs. The adult crabs are delicious…and there is now a large commercial fishery. But with atmospheric carbon dioxide rising, ocean acidity has been increasing enough to affect larval crabs.
Bill describes the project as follows:
"CERCA members are collaborating with other citizen science groups in the Cowichan Estuary area, as well as partners from over 20 other sites in the Salish Sea. The project is coordinated by the Hakai Institute (www.hakai.org ) and runs from April to September.
The monitoring is done by attracting late-stage crab larvae (called megalopae) into light traps provided by Hakai and checking the trap every two days.
Many marine species, including Dungeness crab have a larval phase in which they disperse and grow in the water column before being swept back to the near-shore environment such as estuaries. There they change to the adult form and develop on the sea bottom. By knowing more about the timing and dispersal patterns of crab larvae, we can track their success and forecast adult abundance."
Crab females have been found to carry their eggs more successfully in estuaries. Lower salinity water is detrimental to the worm species that live on the crabs to eat their eggs. Crabs nearer the ocean carry more worms than those further upstream. This made the wharf in Cowichan Estuary a significant place to sample, to better understand how Dungeness crabs were breeding.
After we gathered with Bill and Goetz, we unlocked a series of storage sheds on a wharf below Cowichan Bay Village and walked out to where the trap had been hung off the deep end of the wharf. The trap supplied by Hakai Institute was constructed of funnels that guided free swimming, light-seeking animals toward an interior LED lamp, but made it difficult for them to leave. The light was battery powered and on a timer.
Bill guided the students through the removal of the light trap from the water, then the dumping of the contents into a basin. Another student recorded what we had found using Bill's identifications.
We found no crab larvae. Bill noted that late May was only the beginning of the crab breeding season, and expected larvae would begin to show up later.
However there were instead three rarely seen kinds of creatures. There was a pipefish about 10 cm long. There were four polychaete worms, partly bright red and feathery, that tried to stay in the shadiest side. There were two tiny, very active amphipods scooting around the basin.
While one of the students recorded the catch in a standardized format, another checked the timer and batteries. Meanwhile a third student was squatting down by the basin, fascinated by the animals.
He became still for many minutes, only watching.
Eventually the trap was reassembled and lowered back into the water, and the catch had to be gently returned to the water.
There was still much of the afternoon left, so we moved everyone by car to the other side of the Estuary, to the Cowichan Estuary Self-Guided Nature Trail Open Air Classroom. Goetz was adding another nature-interpretive sign, which needed a post-hole. I went with two of our students. One was the same youngster that had so carefully inspected the marine creatures emptied from the light trap. Goetz showed where they should dig a foundation hole for the sign post. The young man took a shovel and the girl a pickaxe. They set to work until they had a hole big enough for the wood frame mould Goetz had brought. Later Goetz would bring cement and anchor the post.
We had a few minutes wait while Goetz attended to the other group. The boy again knelt down, as he had with the bowl of marine animals, and studied the fresh earth they had exposed. I saw only a mix of sand and smoothened riverine gravel.
He was motionless for many minutes. Suddenly he reached into the pit and carefully picked out a tiny grasshopper.
It was so small it must have been freshly hatched, a "first instar" nymph. I could barely see what it was.
Grasshoppers adults are known to bury their eggs a few inches into soil in the fall, to hatch in spring. Nymphs molt their exoskeleton about five times before reaching adulthood at 40 to 50 days.
I thought this young student had potential as a scientist. I was impressed by his long examination of our strange marine trap catch, in apparent wonder -- and then again his long concentration on the pit of fresh soil, to carefully pick out the tiny new grasshopper.
These experiences are the roots of citizen science…and perhaps of many professional scientists too.
