Being by the water is one of my “happy” places and an ocean coast is one of my favourite places to be (a good reason to study seabirds!). The sound of the water splashing against the rocks, the smell of salt in the air, and the sight of the horizon as far as the eye can see, all add to the experience. However, each coast is slightly different in topography, geography, and biology.
One thing that is consistent among ocean coasts is the tides. Tides are the rise and fall of the water level as a result of the gravitational pull from the moon and the sun in addition to the rotation of the earth. Tides are a very neat phenomenon and on the coast they are often quite dramatic. However, if your field work requires you to be on a boat in the water, you are stuck having to schedule your days around them. I’ve encountered these intense tides during some of my field work experiences on two of Canada’s coastlines.
Fun(dy) tides on the east coast
I took a field course titled “Marine Mammals and Seabirds”, based out of St. Andrews, New Brunswick. The field station we were staying at was in a cove just off of the Bay of Fundy, which is known for having the greatest tides in the world. Tides there can range over 14 m! If the title of the course gives anything away, it is that we needed to be out on the water to have a good view of our study species. Due to the great tides, our boat would move up and down substantially when tied to the dock. In order to get into the boat safely when the water level was not too low, we either had to leave very early (before the sunrise) or we would have to wait until closer to lunch time. You can probably imagine how hard it would be to get 20 undergraduate students up before the sun every day, but somehow we managed to do it (even if we had to climb down a little farther to our boat)! On days when the tide was too low, at least we got to explore the intertidal zone that is normally underwater (but that warrants a whole new post, or check out last week’s guest post The Sea).
Rocky west coast
One day when I was doing seabird fieldwork on Haida Gwaii, British Columbia, we had to travel from the east coast of the south island to the west coast of the north island. We had two choices: we could either sail around the northern or southern tips of the archipelago (would take days to arrive) or we could travel between the two islands through a channel called the “East Narrows”. As you can guess by the name, it was very narrow, with towering cliffs and trees on either side of the channel. The tides were very evident in this channel, ranging from 0.1 m to 4 m over the course of a day. Therefore, we had to plan our voyage perfectly so that we would have enough time to make it to the other side of the archipelago before the water level got too low. If the water got low enough, there was a chance we would hit the bottom of the channel and we would be stranded in the middle of the two islands, possibly damaging our boat. Luckily, we had experienced sailors with us who had timed and completed the trip successfully many times!
When we arrived at the northern island, we anchored the sail boat and the captain brought us in a small dingy to the different islands we were surveying that day. One morning, it was low tide and the wind had picked up. As a result, the waves were larger than usual. We headed out to the island and one by one we had to jump out of the dingy onto the rocks.
The rocks on the edge were very slippery as the low tide left the algae covered rocks exposed. One member of our field crew went to jump off, slipped on the rocks, and fell into the cool water! Luckily she was able to climb out, dry off, and warm up before continuing with the day.
In the end, the tide may be low, but I will still be holding on!