Tuesday 30 July 2013

Hiya,

Just a quick post today......First an additional bit of information regarding the radula marks on the surface of the shed units. Hopefully you can make them out and if you can, then you will probably notice that they are arranged in a fairly neat pattern.

This pattern emerges because the animal, in this case a limpet, is foraging for food in an area that doesn't contain much in the way of sustenance. Because of this, it searches in a tight pattern to ensure it doesn't miss anything. You can find similar tight search patterns in mud at the ocean depths where there is a low concentration of edible detritus for the organisms that live there.

It is possible to observe the same sort of foraging marks as trace fossils in rocks which are about 500 million years old. By making the comparision, paleontologists can use this information to assist them in making informed decisions about what they consider to be the type of environment that existed at the time the animal made them.

The present is the key to the past!

Second, I wanted to add in a Google earth snapshot of the sites that we've been sampling just so you have a clearer idea of what's being done.

Site locations for biodiversity study



We were surveying here during the recent very hot weather, dressed in long trousers and wellies for protection against barnacle-rash ( if you've ever fallen bare legged against barnacles you'll never do it again), whilst the population of Galway were sunning themselves in swimwear and taking a nice cool dip as needed.

I'm not sure if I'd prefer rain but I definitely sweated off a few pounds during the last weeks.

Continue to enjoy the summer,

Keith

13/08/13 Updated the photo to include the final 2 sites; 10 in total

Friday 19 July 2013

Radula marks and other stuff

Hi again,

Dispite our recent warm weather, which has dried up the biofilm on the concrete sheds and therefore all but eradicated the radula marks, I have triumphed and found some traces which are in the pictures below and the area they cover is roughly marked out to help you pick them out.

A radula kind of moves like a band sander, round and round like a treadmill, and scrapes the microscopic bacteria and algae into the mouth of the limpet for breakfast, lunch, dinner, tea and supper.

Picture using a sander up and down in front of yourself in short sections as you stand in one place and moving the sander front left to right as you do so. Once you have completed an arc of sanding, take a step forward and start again. The design you would make mimics the radula marks.




Post survey pictures


Hi,

If you have been looking in on this blog and have noticed a lack of new information over the last few weeks, I can but apologise. I have been away for a wee holiday followed by an intense period of surveys for this and other studies which are taking place within the remit our summer laboratory crew.

Also time consuming is the fact the during the biodiversity surveys within Galway bay I usually bring back a bucket of species, usually algae/seaweeds, which I haven't being able to identify in the field. The next 1 to 3 days can include periods of searching through indentification guides and squinting into microscope lenses in order to make a positive identification of all the species.

Speaking of species, the strange greyish-purple monster that featured in the last post to this is actually a very small critter called Anurida maritima, (it has no common name that I know of )its about 3mm long and lives on the surface of the water in groups. It's an arthropod of the class, Collembola.

One of the features of collembolans is that they aggregate into groups and exude a chemical signal so that they can home in on each other if they get separated. They have a hydrophobic "skin" which allows them to float on water and if they get separated from the group because of a wave you can watch them re-amalgamate like the liquid metal terminator in Terminator 3. They are scavengers, feeding on dead marine animals such as limpets and periwinkles.

Coincidentally, Anurida maritima was one of the handful of animals that we found in our artificial rock pools during the first official survey that we carried out 1 month after their construction.

During the survey we found common shore crab, dog whelk and periwinkles within the pools


Common shore crab ( Carcinus maenas)
 You might think that the shore crab in the picture opposite probably simply got stranded in the pool when the tide retreated however, due to the rough texture of the pool sides, crabs of this size are easily able to exit the pools so in all probability its presence in the pool is by choice.


Common periwinkle ( Littorina littorea )

Dog whelk ( Nucella lapillis )

 
Mud attaching to the pool sides