Taking saltwater samples - not having much luck

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macnmotion
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Taking saltwater samples - not having much luck

#1 Post by macnmotion » Fri Dec 16, 2022 3:06 am

I've found it quite easy to find life in the various freshwater samples I've taken. 2 weeks ago I took saltwater samples while visiting a beach community, and came hope mostly empty handed. All three samples were essentially devoid of life when I returned home, but one of them developed quite a bit of ciliate life in the 2 weeks since as things decayed. I was quite surprised, I had expected quite a bit of life and diversity in the marine samples.

When I took the samples, I made sure to take something green that hadn't seemed to dry out along with plenty of water. One sample was of sand and water right at the beach about 10 meters out, further than where th tide would have pulled out past. So what am I doing wrong? Is there a trick to getting a good marine sample? I have a friend who will be at the sea this weekend, it would be nice to have him collect a good sample for me.

For reference, here is one of the locations I sampled. I took green algae, brown algae and water. I found almost no life initially, but it has exploded with euplotes and cohnilembus since (I've given some flakes of oatmeal and kept it under my plant light for the past 12 days). This was at low tide -- the water was crashing and sloshing onto the algae so it was always soaked.
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Sure Squintsalot
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Re: Taking saltwater samples - not having much luck

#2 Post by Sure Squintsalot » Fri Dec 16, 2022 4:21 am

Low dissolved oxygen is usually the culprit for lifeless waters. All it takes is enough (artificially derived) nutrients to spawn an algal bloom that robs the local waters of much-needed oxygen. Touristy, overpopulated beach communities are notorious for having surpluses of poorly designed septic systems, overwhelmed water treatment plants, and fertilizer-rich run-off from fancy landscaping. Poor local currents and slow circulation may add to the problem of stagnant, slow-moving "dead zones". It's a growing problem in a lot of coastal communities.

macnmotion
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Re: Taking saltwater samples - not having much luck

#3 Post by macnmotion » Fri Dec 16, 2022 4:52 am

Thanks for that response. Perhaps I'd have better luck in one of the many channels bringing seawater inland to rice fields and salt beds. I'll try that next time.

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imkap
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Re: Taking saltwater samples - not having much luck

#4 Post by imkap » Sat Dec 17, 2022 11:56 am

In summer you can dive and take a bit of seaweed, there is usually a lot of specimen on it. You could go in with rubber boots and turn the stones (or if there is some seaweed pick it) in the shallow water and find something there and put the stone back the way it was...

Plankton net is great too. We just came back from a session
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Dennis
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Re: Taking saltwater samples - not having much luck

#5 Post by Dennis » Sat Dec 17, 2022 12:45 pm

Maybe go at low tide and then can look at sources usually under water.

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patta
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Re: Taking saltwater samples - not having much luck

#6 Post by patta » Sat Dec 17, 2022 1:15 pm

I'm taking saltwater samples often, and they vary a lot: often nothing, while sometimes they packed full of different swimming beasts.
Agree with previous post, muddy water is likely barren desert.
One strategy is to follow the fishermen: when and where there are fishes, there are also micro algae and ciliates!
My best samples came in early spring, melting snow and the "right amount" of nutrients (Norway); clear water from the harbor. I don't have a plankton net, take a bottle of water and filter it with coffee filters.

macnmotion
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Re: Taking saltwater samples - not having much luck

#7 Post by macnmotion » Sat Dec 17, 2022 3:37 pm

Thanks everyone, some great thoughts. I'll let you know the next time I have a chance to get a marine sample.

Dennis
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Re: Taking saltwater samples - not having much luck

#8 Post by Dennis » Sat Dec 17, 2022 5:00 pm

macnmotion,

How about water from a rice field ?
And then a photo of the rice field.

macnmotion
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Re: Taking saltwater samples - not having much luck

#9 Post by macnmotion » Sun Dec 18, 2022 1:25 am

I passed so many rice fields and salt fields a quarter mile inland from the sea while driving home, but didn't have any more containers. Next time.

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