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Ocean acidification effects on Calanus

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  Much recent research on zooplankton evaluates the effects of climate warming and of progressing carbonic acidification in both oceans and lakes. Oar Feet and Opal Teeth ( OF&OT ) summarizes the results of studies of copepod responses to century-scale acidity change (about -0.02 pH units per decade since 1985) as “reasonably resistant.” The book provided no review of that research, and one won’t fit in an “OarFeet.com” essay. However, I was attracted by a 2023 paper by David Fields, Jeff Runge, and eight colleagues: "A positive temperature-dependent effect of elevated CO 2 on growth and lipid accumulation in the planktonic copepod  Calanus finmarchicus. ”  Limnology and Oceanography   68 : S87-S100. The title suggested that, for one copepod species at least, acidification could even be a good thing. For me the results also emphasize the accelerated patterns of copepod development and growth, a recurring source of interest for my career.    ...
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Chapter 12 of Oar Feet and Opal Teeth covers egg to adult development of copepods

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 Chapter 12 of Oar Feet and Opal Teeth covers egg to adult development of copepods. It includes a section on how stone-like teeth, clasped like jewels in chitin bezels, come to sit on the outside of the mandibular exoskeleton. Long ago, coauthors and I wrote a paper 1 to summarize our work toward understanding the process. Recently, while discarding old files, I found some transmission electron micrographs (TEMs) we did not publish. Perhaps that was because of some displayed gaps in tissue preservation. However, these sections cut along the cores of the “duct” we believed carries a silica-bearing substance from a gland at the base of the mandible to the fibrous tooth molds on the developing jaw edge (Figure 12.19B in Oar Feet and Opal Teeth ). Duct is in quotes, because there seems to be no actual lumen. The sections (Figures A & B) show the ducts’ distinctive structure of osmophilic (osmium staining) “lamellae.”  Those appear to have been moving oval inclusions toward...
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