Fish in the Bay UPDATE — Green water & the proper trawling invocation

RE: Fish in the Bay – 9 July 2017 UC Davis trawl – Green Water & Low DO

Folks, Shortly after I sent my last fish update, I got good responses that I intended to pass on.  An unfortunate family event interrupted my plans, but with that over, these are a few comments and corrections from local experts in the email chain:


From Tara Schraga, USGS:

1) From eyeball color perception alone, we can’t be certain that the green pond water in July was actually chlorophytes. Diatoms are still a possibility. More investigation is needed.

2) Tara reminded me that a 2008 paper by Thebault, Schraga, Cloern, and Dunlavey, and related posters, documented massive phyto food production in Pond A18:  production equivalent to 11 to 163 million planktivorous fish or 19 to 78 BILLION small estuarine clams between May and October!

The paper is “Primary Production and Carrying Capacity of Former Salt Ponds After Reconnection to San Francisco Bay.”

From Scott Katric, an engineer on our SJ-SC RWF staff:  Scott provided more photos of green water discharging from Pond A18 in mid-July (above & below).  We were continuously tracking water quality parameters, including DO and pH, and we took samples of fish, phytos, and benthic organisms during the month.  This green water seems to be causing no disturbance in the force, so to speak.  All other parameters indicate a fairly robust and healthy estuarine environment, albeit populated with lots of non-native species, like most of SF Bay.

As Scott’s photos show, Pond A18 was emerald green in mid-July.  With some degree of caution, I want to say “Green is good,” or at least “Green does not appear to be impairing.”  This is what up to 78 BILLION clams worth of food production and massive carbon sequestration looks like.


From Christina Toms, Water Board Staff:

1) Christina shared a pdf report: “How frequent storms affect wetland vegetation …” by Joy Zedler that discusses how salt marsh plants bounce back after extreme wet weather events.  Hopefully, this is what we are seeing in Pond A19 this year.

2) Christina also asked for higher resolution shots of the broad leaf plant that, at least temporarily, started to colonize Pond A19.  From the shots below, she and botanist Peter Baye, concluded that this newly observed plant is Atriplex prostrata, aka: a form of non-native “fat hen.”

Atriplex prostrata it is!

Above:  Niaids (in creek) Dryads (in trees) with river spirit further upstream. (from Walter Crane (1845-1915) “Dryads & Naiads”)


Dr. Jim Hobbs, UC Davis, gave us the proper invocation for trawling in the Alviso Marsh (always with donut sacrifice):

“In the name of the river nymphs of the Alviso Marsh
 the naiads and dryads of Coyote Creek
 the gods; Poseidon, Triton, Neptune and Hercules (because we like him)
we make this offer of tasty treat in exchange for a safe day on the water and many native fish”



I wanted to share these comments and corrections before much more time passed.  We have well over 50 bonafide environmental experts on the email chain.  Any statements I make are subject to correction or elaboration.  It is fantastic that we can focus so many trained minds on this interesting and evolving corner of the Bay.


Jim Ervin
Compliance Manager
San Jose-Santa Clara Regional Wastewater Facility

Leave a Reply