Mozdivers - Technical & Research Facility: maio 2015

Bom dia!

So much has happened since the last post.

Last week we started with Manta ID dives. Epic!

I was a little skeptical about going out to dive for the sole purpose of seeing a manta, as I know how rare sightings can be. Especially considering the site we were going to was a maximum of 16 meters, and I’m used to only seeing them at 30 meters in Tofo. Mantas visit the shallows due to the cleaning stations on the reef. These stations have cleaner wrasses, sergeant majors, and surgeon fish that pick parasites of other fish. They get a free meal and the visitors are parasite free, win win! Zavora has many cleaning stations, and we conducted the identification work on three situated close enough to visit on the same dive. The point of these dives is to take video/photos of the mantas ventral side. They have black spots and grey patches on the gills, pectoral fins and the belly which is unique to every manta, functioning as a finger print. Thus, there is no need to mark the manta when doing population studies etc., and is way less invasive and stressful for the animal. Some mantas even have huge chunks taken out of their fins by sharks, making them easy recognizable.

This is the kind of shot we're after.
You can clearly see the spots and patches, and large scars if there are any.

The first dive started very slow in terms of mantas. We did see a leopard shark and an almost 2 meter wide blotched fantail ray, but no mantas in site. After 40 minutes it started getting cold and we were at the third cleaning station, having 5 minutes left on the timer. Finally our first manta decided to appear. It came straight for us and passed over both Yara and me several times, giving us very good photos to use later for identification. Success!!

Me with my selfie stick which lasted one dive.
It's really nice for getting close ups of the belly.

The second dive was the same sites, but a whole different story. Within the first 5 minutes we had two encounters with the same manta. Two more on the last cleaning station, one of which drove me away from Yara as I was too busy filming it that I didn’t pay attention to where I was going. I looked for Yara a bit, but the visibility was bad, so I decided to just go up. Just when I was reaching for my SMB, another manta decided to show up! I love how they just come straight toward you, and all you have to do is point your camera upwards and let it slowly pass over you. Needless to say, the day was a success, and we could enter 5 more reef mantas to our database!

The next day we had two more mantas, one being a resight from the first day. The third day we went to an offshore reef, about 10 km from the shore. The purpose of the dive was to change a temperature sensor located at the bottom (34m), and I had the task to unscrew the old one and install the new. The visibility was superb, and straight after we dropped I saw a giant manta hovering above the reef. Instinctively I went for it, completely forgetting the purpose of the dive. Halfway there I remembered, and gave up the manta. When I turned around and started swimming towards the others and the sensor, I saw three more giant mantas circling the reef! My heart was pounding, knowing how awesome it would be to put in some giants in the database, as most of the mantas there are reef mantas. Jon signaled to me that one of us had to go take photos. I was the only one with a camera, so he took over my original task. The mantas were so friendly, stopping beside us, checking us out, and turning around again and again.

Sometimes the mantas have so many remoras or sucker fish, you can't tell where the spots are. Filming instead of taking pics usually solves this problem.

The last dive of the week was the wreck Rio Sainas for a fish survey. During the survey we basically spend 5 minutes at different stations on the wreck, write down all the species of fish within a 2 meter radius, count them and note their size. The information is used to monitor the colonization of the wreck and how it changes over time. Key species were three HUGE brindlebass or giant groupers and annoyingly close longfin batfish. Very, very nice dive, but it’s quite deep so there was only enough time for the survey.

The end the week was used to dissect nudibranchs. We dissected two that were marked as Chromodoris hamiltoni, but which could be two different species. One of the ways to find out is dissection and looking at the radula (nudibranch teeth). Jeez, dissecting a 25mm organism is meticulous work for someone who has never dissected any animals smaller than a squid. The insides of a nudi are so fragile, so it was a bit nerve wracking. Did you know that nudis are hermaphrodites? It basically means you can find both the male and female reproductive systems in one nudi. The reproductive systems in our nudis were very different, so we might have two different species. After drawing the systems and the foregut, we put the foregut in acid to be left with only the radula. This has to be sent to a country with an electron microscope to be covered in gold and photographed. You end up with a super detailed photo of all the tiny, tiny teeth so they can be counted and used in the description of the species. How cool is that!

Poor little nudi

Otherwise, the tide has been low and springy the past three days, so we’ve spent every morning in the rockpool photographing invertebrates, nudis and fish to make ID-slates specifically for the rockpool. I never get sick of this place, there is life everywhere. I found five different nudibranch species on the underside of the rock I usually put my gear on. One of which is newly observed in Mozambique. Here are some of the photos