Bermuda: Tobacco Bay

Location and Study Site

Tobacco Bay is a beautiful and popular bay on the north shore of Bermuda (Figure 1). Besides its small cantina, Tobacca Bay is famous for its intricate and bizarre rock formations (Figure 2). The formations have allowed for a diversity of species to colonize the area and make for fantastic snorkeling. The formations also make Tobacco Bay an optimal site for studying limpets.

Bermuda is a ridge island, emerging about 110 million years ago from the Mid Atlantic Ridge where a small volcano erupted. This volcano, named Mount Bermuda, moved slowly away from the Mid Atlantic Ridge over the following 60-80 million years before undergoing a second series of eruptions, which occurred about 30 million years ago. The base of Bermuda is made of hard, black basalt, remnant from the volcanic activities. The surface of Bermuda is made of sedimentary limestone, due to a process called bioconstruction or biodeposition. At periods in Bermuda’s past (~900,000 years ago during the Pleistocene), the basalt foundation rested below sea level. Two principal groups of organisms, hard corals and coralline algae, colonized the basalt and created calcium-carbonate skeletons as they went. Over time these skeletons broke down, collected as sand, disintegrated under slightly acidic rain, and re-condensed to fossilize and form the surface of Bermuda.

Tobacco Bay’s rocks are visibly made of condensed sand, though much worn away through physical erosion and bioerosion. These intricate limestone outcroppings are optimal habitat for limpets, chitons, periwinkles and other algal grazers. They provide extraordinary amounts of structural complexity, a constant food source, and access to water dispersal via changing tides.

Sources: Thomas, Martin L.H., 1997; Thomas, Martin L.H., 2002.

Tidepool Choice

Behind Tobacco Bay there is a portion of the north shore with an extensive rocky intertidal zone (Figure 3). This area is only accessible either by swimming out of the bay and around the northern edge of the rock formations, or by scaling the steep rock walls. The isolation of these zones made Tobacco Bay an optimal study site.

I selected a tidepool that was approximately 40cm x 25cm and that did not contain any limpets. It was never less than 5cm deep even at low tide and was covered at high tide.

Figure 1. Tobacco Bay on the North coast of Bermuda, circled in red

Tobacco Bay Beach

Figure 2. Intricate rock formations

Tobacco Bay Coast

Figure 3. Protected intertidal behind Tobacco Bay