As a project, we hope to observe and model the currents between the island and the mainland, a majority of which is due to tidal motions which are comparably easy to understand. The project has therefore redefined it's goals to analyze nonlinear tidal motions which are created as a result of the large tidal swings in variable topography as well as currents not directly influenced by tides.
|Javier, Mucaco, and Connor preparing the Current Meters|
This Thursday, we will be conducting our first cruise, a half-day out to Chumbe Island to test all of our instruments and techniques, as well as deploy current meters to measure the predicted nonlinear tidal motions around the island. Chumbe Island is a marine reserve, and the snorkeling is expected to be excellent. This is exciting for me, as my main focus, interestingly enough, is on the biology portion of this project.
The sewage from Stone Town is let out of a pipe just offshore. While it is treated, this still poses a threat to the biology of the region (e.g. I won't swim near town). We hope to add a tracer to our model with the hopes of understanding the dispersion of this sewage. To provide an in situ comparison, we will be measuring biological quantities with hopes of creating an environmental gradient of the affected area.
|Ali in the machine shop at IMS|
Snapshots of sewage dispersion will be found using chlorophyll and suspended solid measurements, using a small boat on three separate days. We hope an average of sewage dispersion will be given by coral health found with photographic techniques. I have spent much of my time here so far constructing a frame which will ensure consistency between pictures. For example, I spent the morning yesterday snorkeling north of town as we determined the correct height to capture a 1x1m sample area with a photograph. We then enjoyed the bar with sand beneath our feet.
-While the project has its basis in how toxic the water is, we are looking for proxies outside of the dangerous zones (i.e. coral gets sick before humans do). I do not expect to be in contact with water any dirtier than San Diego after a rain.
-Yesterday, a fisherman accidentally drowned a dolphin in his net and brought it to IMS for measurements, dissection, etc. The dolphin was three years old and very healthy looking, except for being dead. According to the institution's dolphin graduate student, bycatch claims about 80-90 dolphins per year in Tanzania. 2006 was a bad year, with ~1000 dolphin strandings; there was no connection made to anthropogenic or other causes.
-To help with this project, I made an investment in an underwater housing for my camera. Once I get comfortable with it, you can expect pictures from snorkeling, diving, and eventually surfing.