Dumb oceanography question...

[Gidds]

When I snorkel on the weekends I like to stay all day. Yesterday I arrived at the site around low tide and the vis. was excellent. As the day progressed and the tide started to come back in the vis. went down the tube. Can somebody explain why? Also what other biotic and abiotic factors effect vis. ?

 

[archman]

Hmm... that sounds reversed for what happens to us in the Caribbean. High tide brings clearer water. Ebb tide removes stained and silted up water. Granted up north there are much greater tidal cycles, more plankton, and potentially greater particulates to become entrained in the water column. I would hazard a theory that your vis improves when currents calm down (slack water), and can potentially worsen when currents pick back up. If your vis worsens when the tide comes IN, it is likely that your offshore waters are dirty or getting stirred up in transit. We have tidal passes in Texas that look like underwater sandstorms when the tides are running.

Inshore water clarity is affected predominantly by:
1. sediment entrainment (smaller particles stay up longer than coarse ones)
2. plankton
3. rainfall & runoff
4. river discharge
5. natural dyes (vegetation breakdown)

 

[Gidds]

Hmmm thanks It could just be that low tide is in the early afternoon at the moment so all the boats and such stir up the water that then comes back in when the tide turns. I was born a landlubber so I'm still trying to get a handle on this whole ocean thing. Lakes I can handle or a river with a decent current but the ocean is a bit beyond me at the moment