Cerith snails and Seagrasses...

[RESONANCE]

What are your experiences and opinions about having cerith snails in a seagrass bed/ aquarium? Do you think they are beneficial or detrimental for seagrass beds?

[RESONANCE]

So I have a 40 breeder where I was trying to grow some oargrass. The oargrass started spreading out pretty well albeit it was a thin cover on a large area. The leaves remained small (same size as when I got it) and never reached the size as it appears in Amphipiron1's tank/ pictures. About a month or two after planting the oar grass, over the course of 2 weeks I introduced 20 or so normal sized cerith snails figuring that with my 5 - 6 inch deep sand bed there'll be a need for something to stir the sand up a bit.

 

This is where the dilemma begins. The cerith snails do a decent job of stirring the sand... I'd say at anytime there are about 5 to 10 of them digging around while the others are on the surface eating algae. BUT, then I started noticing my oar grass stopped growing/ spreading. And over the course of 2 months ALL of my oar grass disappeared. I was thinking at first, maybe a lack in nutrients - but that didn't seem right considering that I introduced the grass when the tank was brand spankin new - and even then, the oargrass spread quite rapidly. The sand was bought from some one else's old system so it had a decent supply of nutrients. Also, as time went by I could see more and more tiny substrata fauna in the sand, all of which should be aiding sea grasses.

 

One day, I noticed one of the cerith snails surfacing from beneath the sand. Lo and behold! As it surfaced, it unearthed some oargrass rhizomes with it, essentially uprooting a few of the seagrasses. This is the only explanation that I could think of about why my oargrass declined and disappeared. I haven't observed any of the snails eating any parts of the grass, but I think that their constant digging and surfacing may disturb seagrass root and rhizome structure to the extent that the entire bed eventually declines and dies.

 

What do you all think about this? Any opinions or experiences?

 

How about in the wild? Aren't there critters that'll dig up the sand where sea grasses occur? Or do you think it's just oargrass that's really delicate and sensitive to being disturbed?

 

Discuss!

[seabass]

I guess I can imagine that's possible. They feed on algae, so I could see they might be interested in feeding on some young roots. I have one larger Cerith and a few Dwarf Ceriths and haven't noticed that yet. However, the larger one does bulldoze it's way around the surface. Maybe it was the shear number of them?

 

Astraea and Cerith snails, as well as Strombus conchs, have so far proven themselves wonderful algae grazers without preying upon the grasses in these setups. Urchins, however, are under suspicion of grass consumption. Care should be taken when introducing other invertebrates to evaluate whether or not seagrass is on the new additions' menu.

- Beyond the Refugium: Seagrass Aquaria by Sarah Lardizabal (Reefkeeping.com)

[RESONANCE]

Yeah, possibly. I figured a 40 breeder would be big enough for 20 ceriths. Didn't think they'd crowd the sand too much. There's so much surface area for them to cover besides the sand and glass, theres all that live rock, etc..

[johnmaloney]

they dont have the cutting power to eat it

[seabass]

RESONANCE, what type lighting do you have? Also, what temperature do you keep your tank at?

 

My first attempt also failed. This time I have better lighting, keep the tank at 80 degrees, dose CO2, and have a different and deeper substrate (with Fiji Mud). That's a lot of changes so I can't say what might be the cause for the improvement.

 

I'm still trying to figure it out too, so I really appreciate having someone like John around.

[RESONANCE]

6 light TEK T5HO, Temp at 78 F (winter - in basement). I dose Iron/ magnesium from Kent (or is it seachem). As I initially said, before the cerith snails were added the oargrass seemed to be spreading out pretty good.

 

RESONANCE, what type lighting do you have? Also, what temperature do you keep your tank at?

 

My first attempt also failed. This time I have better lighting, keep the tank at 80 degrees, dose CO2, and have a different and deeper substrate (with Fiji Mud). That's a lot of changes so I can't say what might be the cause for the improvement.

 

I'm still trying to figure it out too, so I really appreciate having someone like John around.

 

Hi John,

 

So what's your take on this? Do you think cerith snails are harmfull to new seagrass beds? What about in the wild, do cerith snails occur where seagrasses grow? Thanks.

 

they dont have the cutting power to eat it

[johnmaloney]

seagrass beds are dominated by ceriths, conchs and astreas. that is really where they come from. they clean the seagrass all day long usually. the seagrass depends on them to remove epiphytes and their concentration per sq. foot is way higher than anyone keeps in captivity.

 

seagrasses seasonally die off, usually dont have to experience season in captivity, but I wonder did the blades die or the roots too? blades come and go, only the roots matter.

[RESONANCE]

Thanks John! Perhaps then in my tank's case the tank and/ or sea grass bed too new?

[johnmaloney]

if it grew and then died back something changed, but I dont think the issue is it was too new, it wouldnt have grown in the first place.

[RESONANCE]

Yeah, it's really odd cuz the only thing that changed was an increase in the bio load, but that should have actually helped with the grass growth - or atleast not affect it.

 

The only other thing is that I'm not sure if I had my mexican turbo snails in there at the time yet. These were the same snails I caught snacking on my fire fern macro and red titan algae. I never saw them show any interest in any of the oargrass. To be honest, I can't even remember if I had them in my tank when the oargrass was still alive. I'll have to check my old pictures.

 

if it grew and then died back something changed, but I dont think the issue is it was too new, it wouldnt have grown in the first place.[/quote

[Amphiprion1]

I've had a little over a dozen ceriths from the beginning with my grasses. They have never been an issue. If anything, they are somewhat beneficial in that they occasionally consume the microalgal films that can develop on grass blades. I also highly recommend Euplica snails, as well.

 

I can't speak for everyone, but I have regular die-offs in my system in regards to seagrass. They seem to reach a critical mass (very dense growth), die off, and then regrow. They've done this from the start. I think if they were harvested more regularly, it might stave it off a bit longer. But then again, some grasses have shorter life spans than others. My Halophila has one of the highest turnovers for individual rhizomes. Compare that to Thalassia, which lives for years.

[RESONANCE]

My oargrass never even got close to the density as seen in your tank unfortunately. Still they disappeared.