Life Cycle Completion in Brackish Ponds?

[Veneer]

In Puerto Rico, I observed an artificial pond (fountain, packed-dirt central "island") situated by a hotel within 100 meters or so of the ocean. Shrimp species observed were Palaemon pandaliformis, Macrobrachium faustinum, M. acanthurus (and possibly M. carcinus) as well as Xiphocaris elongata. I saw berried P. pandaliformis alongside juveniles of all sizes, as well as young M. faustinum and M. acanthurus. Cardisoma guanhumi were to be found in burrows by the water's edge; other fauna included Sesarmid crabs, slider turtles, tilapia, large loricariid catfish, and an assortment of native gobies (ranging again from tiny juveniles to finger-length adults). No salinity measurements were taken, and no flowing-water connection to the ocean was evident. Perhaps temporary oceanic connections would emerge via roadside dirt drainage ditches if the pond were to flood the surrounding terrain, but the sheer prevalence of tiny specimens was suggestive.

Have any accounts hinted at catadromous or amphidromous shrimp "landlocked" in brackish pools? When in the Galapagos, I heard claims that M. americanum occurred in coastal environments of this nature, but never saw any firsthand.

[pixl8r]

That is very interesting. It is my understanding that those species of Macrobrachium shrimp do require brackish water to full marine water to mature from larvae to adult shrimp. I wonder if it is possible that someone stocked the pond...

I would love to get some M. acanthurus to breed. I'm still anxiously waiting for my M. cf scabriculum.

[Mustafa]

A lot of coastal freshwater or brackish ponds, both surface and subterranean, especially highly porous volcanic or coral-sediment areas, have sub-surface connections to the ocean. The juveniles seem to reach these pools through these connections to the ocean. I have personally observed and caught Macrobrachium carcinus in a highly brackish anchialine pool on curacao in a cave, that have absolutely no obvious connection to the ocean and no river nearby for miles. There were other Macrobrachium spp. in there that also must have settled there from oceanic larvae. Due to the fact that this particular pool was pitch black (in a cave) there was no planktonic life to support any larvae. I really doubt that a small/medium sized pond, brackish or not, could support entire larval development cycles.

[Guba]

This thread got my wheels and gears turning. My question is, would it be possible for those coastal ponds to be introduced by tidal surge from say, a hurricane or maybe a tsunami? I've never been in any of those situations to see what they're like, but the videos on the news the last couple of years really impressed me. If larvae are moved about by currents it seems to me that maybe some could survive if they weren't thrashed around too violently.

[pixl8r]

I'm sure that something like that is possible. However, the larval shrimp would have to be at the perfect stage to reach post larva. And since those types of oceanic events are infrequent, I doubt that any type of sustained Macrobrachium shrimp population could survive for very long (a few years or so).

I loved searching around the tide pools in Southern California and Hawaii. But back then, I either didn't have an aquarium, or I wasn't inclined to capture any animals. Much of my searching was not just due to curiosity, but watching out for jellyfish, urchins, and anemones. Then it was off to the surf, to surf.