Bob, the mismatch in the upper left corner is just two different years of data, note MAY-AUG on one arrow and JUL-SEP on other; I would start with the NOV-DEC part of the cycle

Dave,  This slide is meant to show actual conditions during cruise with Greg.  The density structure could not be used in the usual way to help define the front.  Working with Greg and Jim Manning we settled on the top-botrtom delta T.  We sued the temp at 5 m to avoid the excessive sfc warming we had some days.

Using drifters, models and water column properties, we moved on- and off-shelf with the front to maintain our sampling in the three water types (crest, front and strat.)   Here are the mean concentrations and structure (variances not shown for clarity).  Taxonomic composition is shown in the next figure.

Frontal stations very similar to strat.

Taxonomic composition (species and stage abundances) vary from station to station.  We are looking at the value of aggregating data by major life history stage (copepod/nauplii) and size as a way to characterize the particle environment that larvae encounter.  This is not to say that all similarly-sized particles are the same because, for instance, they may not all be similarly detectable or catchable.  But—here it is (next slide).  Note, we increased the length range in each size category in order to maintain viable sample sizes—the larger the organism the fewer there are in a sample (our pump samples have pretty small volumes, which is a trade-off for the high vertical resolution and small mesh size (40 um).

Size composition is similar from 25-30 m in all three areas.  There are proportionally more small particles in the shallower (15-20 m) layer.  At 15-20 m the front and strat are similar and about 2x the concentration found in the mixed area.  If you go all the way to the max. concentration at 10 m (see Fig. 3, repeated in next slide), then the strat. zone is the richest in prey. Only in the strat. area do you see an appreciable proportion of cod larvae this shallow (10-20 m in Greg’s MOCNESS tows)—perhaps the light conditions are different.  We need to look at light, size of cod, etc.  See last figure, from Greg.  Is food limiting in any of these situations at any of these depths when we consider size, turbulence, light, etc?

Using drifters, models and water column properties, we moved on- and off-shelf with the front to maintain our sampling in the three water types (crest, front and strat.)   Here are the mean concentrations and structure (variances not shown for clarity).  Taxonomic composition is shown in the next figure.

The columns for size and abundance of cod larvae are place holders—we need to ask Greg for these values—for now, just leave them in to show work in progress.