Life Between Grains of Sand
Walks on the beach will never be the same again.
Standing on the edge of the land and the sea, and feeling the sand on the bottoms of my feet: that is my favourite moment on the beach. I get dizzy from looking at the movement of the tiny sand grains in the down wash, from thinking about the gazillions of repetitions of this restless wave movement in beach formation, and from imagining the secret lives thriving there.
The intertidal sandy beach zone is a highly dynamic environment. At different times each day it can be the land and the sea, and it is constantly changing wave by wave, tide by tide and storm by storm. As a result, there is no vegetation that you can see; the first impression is that this place is a desert. But this is far from reality – the truth lies between the sands.
If you put a spoonful of beach sand under the microscope, you’ll see tiny creatures frantically swimming and crawling all over the place. They are mostly single-celled microbes. Some are colourful microalgae, such as diatoms and dinoflagellates. Some are grazers who feed on the microalgae or even smaller microbes such as bacteria and archaea.
This is where I get involved: I am interested in the microbial biodiversity, their distribution pattern on the intertidal sandy beach, and their functional links to the macroscopic members of the ecosystem.
Why are beach microbes important?
Among the grains of sand are microalgae, photosynthetic organisms that produce sugar using sunlight, the trees and grasses of the micro scale. Although each microalgal cell is small (many are around 1/100th of millimeter, or half the width of the finest human hair), their gross production can be substantial. Sometimes they form a dense patch on the surface of the beach, which can be visible as a discolouration of the sand. These microalgae are the major primary producers that supply energy to the beach food web. They support the grazers of various kind, ranging from the single-celled ones, meiofaunal (e.g. nematodes), to macrofaunal (e.g. crabs and clams).
Another important aspect of the beach microbe is their contribution to the resilience of beach ecosystems. With microbes’ fast growth, the microbial community is one of the first to respond the change in the environment. This is a hot topic as the beach is often affected by anthropogenic impact including Exxon Valdez spill on the Alaskan coast or the Deepwater Horizon disaster in the Gulf of Mexico. These unfortunate events stimulated research activities after the disasters, but, without the understanding of the pre-pollution state, it is hard to understand the real impact of an event. At the Hakai Institute we are lucky to have access to beaches with minimum human impact. And considering the increasing shipping traffic in the northern and central BC, the timing is right: knock on wood, but starting a long-term survey here, now, means that we can know the full impact of any future disasters.
What we are doing on the beach?
It may sound surprising, but the biggest challenge for us is still to understand what kind of organisms comprise the beach microbial community. This is because the majority of microbes lack a visual cue for identification. Luckily, the recent technique of high-throughput DNA sequencing allows us to identify members of the microbial community with more accuracy. We are working closely with amazing teams of multidisciplinary researchers (geomorphologists, soil scientists, fish scientists, biological oceanographers to name a few) to tackle the challenge.
Acknowledgements
We are extremely fortunate as Eric and Christina of the Hakai Institute fully support us not only through funding and logistics, but also fostering the mealtime conversations with the other scientists, which often bring us fresh, exciting ideas.