Archivos de Diario para diciembre 2019

01 de diciembre de 2019

Plankton tow on November 29th, 2019

Anticipating the upcoming week of rainfall, I thought I'd check out the plankton in Lake Merritt before the brackish water goes fresh. The surface water went from a well-mixed salinity 32 parts per thousand (ppt) on Nov. 24th to stratified 22 ppt at the top and 31 ppt at the bottom on November 29th after a brief rain when I took my plankton tow. I photographed plankton with my iPhone through a student microscope at 40 and 100 x magnification. The photos are in the Lake Merritt Species Project. It will be interesting to see what changes happen after the storms.

Taken from west side of longer open floating dock.
Water depth 210 cm, temperature 9 degrees Celsius top/12.5 degrees Celsius bottom, dissolved oxygen 4 ppm/3.5 ppm bottom, salinity 22 ppt top/31 ppt bottom, pH 6.5 top/7 bottom, Secchi 110 cm.

Plankton net used was 50um mesh.
Magnification was either 40X or 100X. Photos by student microscope and iPhone.
Rate-Our-Plankton-Density = CLEAR

Thalassiosira (although I think I see two central connecting strands not one)
Melosira, several stages of copepod (nauplius and calanoid?).
Chaetoceros - corkscrew -type (according to hand-out from Romberg Tiburon Center event this is a different species from the straight Chaetoceros), Chaetoceros debilis
Something – Skeletonema?

Copepods: copulating copepods with long antennae, 2 kinds of copepods,
Polychaete larvae with big heads with bristles and skimpy bodies, many zooming trochophore larvae
Flatworm-type worm
Possible barnacle larvae distinguished from copepod nauplii by jerky swimming style (helpful hint from Charles Ford),

When viewed plankton sample was 2 hours -2 days old ☹.

Anotado en 01 de diciembre de 2019 a las 04:42 PM por ktnoon ktnoon | 0 comentarios | Deja un comentario