Last week all eight of us (seven students plus Cynthia Trowbridge) made an outing to the eastern shore of the lough, just above the rapids to familiarize us with the various animals which can be found on clinging to the undersides of rocks.
Now, you’re probably wondering why on earth we are flipping over rocks, when there are plenty of perfectly good right-side up rocks to look at (the lough is, after all, pretty rocky along the shore). Let me explain.
First, flipping rocks in a marine environment is completely different than flipping rocks on land. When you turn over a rock on land, you see dirt and if you’re lucky, you see ants, worms, or pill bugs. That’s all fine and good, but it’s not very exciting. When you flip rocks in the water, you see a whole new world of marine life: bryozoans, scale worms, polychaete worms, ascidians, brittle stars, and sponges to name a few. The surface of the rock is typically much less diverse: a few types of algae and maybe a sponge or two.
The reason for this drastic difference in species is primarily due to gravity. In areas which have very limited wave action, any small particles which are in the water slowly drift to the bottom where they slowly accumulate. This means that over time, the topside of rocks will become covered in a layer of fine particles. This poses a serious problem for sessile (non-moving) animals such as sponges, ascidians, and bryozoans because they will eventually become buried in the muck and die. The undersides of rocks, however, do not become covered by a layer of muck, making this a perfect habitat for sessile animals (think of standing under an eve to avoid the rain).
The second reason we were getting this crash course is so that we could help Colin Little and Penny Stirling survey various sites across the lough. All told there are 10 monitoring sites which have been surveyed every year for the past 19 years (this year is the twentieth). Each site is 10 meters long, and among other things, we flip all the rocks we can along the low shore and record our various findings. Below are some of the creatures we have found, both during our training and with Colin and Penny.
-Dylan Cottrell
Now, you’re probably wondering why on earth we are flipping over rocks, when there are plenty of perfectly good right-side up rocks to look at (the lough is, after all, pretty rocky along the shore). Let me explain.
First, flipping rocks in a marine environment is completely different than flipping rocks on land. When you turn over a rock on land, you see dirt and if you’re lucky, you see ants, worms, or pill bugs. That’s all fine and good, but it’s not very exciting. When you flip rocks in the water, you see a whole new world of marine life: bryozoans, scale worms, polychaete worms, ascidians, brittle stars, and sponges to name a few. The surface of the rock is typically much less diverse: a few types of algae and maybe a sponge or two.
The reason for this drastic difference in species is primarily due to gravity. In areas which have very limited wave action, any small particles which are in the water slowly drift to the bottom where they slowly accumulate. This means that over time, the topside of rocks will become covered in a layer of fine particles. This poses a serious problem for sessile (non-moving) animals such as sponges, ascidians, and bryozoans because they will eventually become buried in the muck and die. The undersides of rocks, however, do not become covered by a layer of muck, making this a perfect habitat for sessile animals (think of standing under an eve to avoid the rain).
The second reason we were getting this crash course is so that we could help Colin Little and Penny Stirling survey various sites across the lough. All told there are 10 monitoring sites which have been surveyed every year for the past 19 years (this year is the twentieth). Each site is 10 meters long, and among other things, we flip all the rocks we can along the low shore and record our various findings. Below are some of the creatures we have found, both during our training and with Colin and Penny.
-Dylan Cottrell