Annelids and Nematodes

Worms, creepy night crawlers.  These whirly wigs can sometimes make appearences in wastewater treatment processes.  Sometime to the chagrine of wastewater operators. If found in large concentrations, they can tinge  the liquid a red to green color.  They are not your normal inhabitants of wastewater plants but they can “bloom”  if certain conditions are present or if you allow them to proliferate.  Now, allowing them to proliferate can mean several things.  Not maintaining proper mixing conditions, allowing solids to settle and creating anaerobic conditions.  Worms, plainly speaking, enjoy stagnant conditions.  Trickling filters, biofilters, any type of fixed film process such as rotating biological contactor (RBC) with little to no maintenance, too high F/M conditons… You get the idea.  These critters can become a nuisance if you allow them.

The photo above is that of a Diplogasteriodes nematode.  The differences between nematodes and annelids are as follows:  Nematodes have a false peritoneal cavity (pseudocoelom).  Their internal peritoneal cavity is derived, during embryonic development, from the embryonic blastocoel rather than the mesoderm.   The annelids are worms whose bodies are divided into similar rings, or segments, arranged in a series.  These segments from the outside, are marked as circular grooves called annuli (thus the term annelid).  Diplogasteriodes live on a diet of bacteria and alga and are usually found in treatment plants with long detention times.  Trickling filters are common sites where nematodes and annelids can be found.

Click on it to view a video on Aelosoma.

Click to view a video about Rhabditis, a nematode.  The last portion of the video shows a gravid female, that is, a female pregnant with live young.  This female will give birth to live young (viviparous) as opposed to laying eggs (oviparous).

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Seed Shrimp (Ostrocoda) 

Temporal rain pools, those pools of rain water (typically referred to as vernal pools) that spring up after seasonal rain events can bring about a Lazarus’ effect.  There are numerous organisms that can arise from near death, suspended animation or hatch from eggs, cysts, or protected shells just at the right time of the year.  All that is needed is a bit of water, sun, and nice warm temperatures to start them up.  Seed shrimp, Brine Shrimp (if you are old enough to remember the comic books advertising them as Sea Monkeys-though they looked like nothing in the ad), and numerous Cladocerans such as Daphnids and Ceriodaphnia species.  In this blog entry, the seed shrimp is the critter of the month.  All these creatures can spring up in secondary clarifiers (after being washed into the treatment system with the rains) when the treatment plant is doing an excellent job in treating the wastewater.  Mind you, these creatures will not be able to survive conditions in secondary clarifiers, holding ponds, and in reclaimed water tanks if any toxicants are present in toxic amounts.  In many ways, you are doing a superb job in terms of treatment that you now allow for their survival.  The seed shrimp presented in the video was found in a treatment system in the Midwest portion of the US.  The term seed shrimp is somewhat self-explanatory in that the shrimp is encased within two shells that form its carapace.  As with any crustacean, they are filter feeders and feed primarily on plankton, alga, yeasts, fungi, bacteria, and detritus that can be swept by their “hairy” appendages.

Seed Shrimp (Ostracoda)

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Barbronia weberii

Barbronia weberii is native to Southeast Asia and the little story associated with this leech starts with a forum posting on Water Environment Federation website by a wastewater operator who was having double trouble in his tertiary filters.  Not only was he having problems with a species of Physa snails plugging up his filters but he also had an infestation of these leeches that were getting into everything.  I posted back that I was interested in trying to determine which species of leech was present in his treatment works.  Several weeks later I got my hands on a sample from the operator’s treatment plant.  The sample was murky (dark brown in color) with assorted large creatures present: several leeches, snail shells, and seed shrimp.  The solids naturally settled to the bottom and you could clearly see the seed shrimp going about their business (swimming up to the surface and dropping like a stone to the bottom) which continued in a seemingly endless cycle.  The leeches would stick to the surface of beaker and swim about to another spot.  I quickly set about trying to identify the leech.  All my books and various internet searches yielded not a single clue as to the identity of this organism.  One last resource I came up with while doing my research was finding a leech expert at EPA.  I managed to find his e-mail address; contacted him, and told him about my efforts to ID the bugger.  He gratefully accepted to ID the leech.  Sent him a few leech specimens.  About a day after he received the leeches he sent me a reply.  He identified the leech as Barbronia weberii.  As far as he was concerned, this was the second specimen found in the US.  The first specimen was found in Florida.  Apparently, these leeches are carried from native areas and unknowingly exported worldwide through the aquarium trade.  Leeches can lay their eggs, or attach to the underside of water plants from native areas and sold to the aquarium trade.  Of course, aquarium enthusiasts buy live plants for their aquariums and along with their plants come unwelcomed visitors.  Unfortunately, these unwelcomed visitors get tossed into streams and lakes and become  invasive species wrecking havoc on the ecology of these water bodies displacing native species.  The EPA expert told me he was going to send the specimens to the Smithsonian and include my name with the leeches.  Now, I will be a known associate of a leech.  The life cycle of the leech involves the presence of a snail.  The leech actually feeds off the neonate snails.  Thus, the presence of both the leeches and snails in this poor operator’s treatment plant.  If he could naturally get rid of the snails it would follow that it would also rid him of the leeches.  The following video is that of Barbronia weberii.  Enjoy.

Barbronia weberii

Physa spp

Physa spp Shell View II

Physa spp Snail View III

Interesting historical/etymological aspects of this entry has to do with morphological characterization of snails.  Typically, the shells of snails are grouped according to which side the opening is situated. “a sinistral gastropod shell with the apex upward has its opening on the left when facing the observer”.  The apex of the shell is most often used to refer to the uppermost part of the shell spire.  Thus, Physa snail shells are left handed or sinistral.  The word sinistral is derived from the latin word “sinister”.  Left handed people were considered evil in olden times and burned at the stake.  There are numerous time I’ve heard the old story where left handed people were hit with a ruler to “mend” their evil ways and start using the right hand.  Most of the times, it was in a Catholic school, where the nuns were strict adherents of ancient  and archaic philosophies.

Physa spp Shell View I