Dive report Okahu Bay: MS1

26 January 2024
8:50am High tide

Launched kayak at the boat ramp and anchored south east of the MS1 bed using my previous observations on the iNaturalist app as a guide. There was barely a ripple on the surface and the sky was clear. My plan was to explore the wider shell area to investigate the mud habitat that had built up on top of the shell over the last two years.

At 8:30am I descended to 6m and was pleased to find 1m vis at on the seafloor. The tide was slack - no current. I could see I was on the shell as in places bioturbating invertebrates had bout small bits of shell to the surface. I swam east to easily locate the mussel bed. The bed looked similar to previous dives but the live mussels did look big. I was pleased not to see any eleven-armed starfish predating the mussels, a dramatic change from March last year. It was also great to see lots of large mottled triplefins in the bed. There was broken mussel shell in the bed and some further out including signs of snapper digging in the bed.

Swimming towards the breakwater I found a weird looking shape in the mud and thought it might be a buried horse mussel, as soon as I poked it I realised it was actually a stargazers mouth! I photographed it then tried to get it to move by pushing my fingers under it, the fish didn't swim away and dug it self back into the mud. I left it hunting and (presumably for bridled goby) and explored the breakwater.

There were clumps of juvenile mussels on the seafloor at the base of the breakwater which is about 1m higher than the surrounding sediment and shelly not muddy. I cant tell if these juveniles attached here or fell of the poles but many looked to be blues. There is more spat attachment substrate like the ostrich plume hydroids near the breakwater than in the mussel bed. I'm concerned about the white bleached look on the finger sponges which can be found on the mussel bed, shell platform and pylons.

I headed SE and then circled back to the breakwater side of the kayak before exiting after 66minutes underwater. The current was only just noticeable.

I just cant get my head around how much mud has accumulated on the elevated shell platform in the last two years. The last monitoring report has it at 2cm. My finger tests definitely confirm that, it might be closer to 3cm.

Posted on January 27, 2024 07:32 PM by shaun-lee