Boat vs backfloat while diving

Re: Atoll divers with bad joints due to mineral deficiency, boats & HV?

http://www.jstage.jst.go.jp/article/ase/114/1/114_1/_article
I'm guessing here, not enough data to be sure:

Atolls typically lack copper and iron which are needed for bone growth.
With that in mind, it seems likely to me that diving while often deeply hyperventilating might induce divers to stay at depth longer, increasing the chance of the bends, or Nitrogen micro-bubbles in the knee and other joints, with increased deterioration of the already poorly integrated tissues over time, especially if stressed (physical work done) soon after diving.
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[still working on this, not sure how much an effect mineral nutrients were in bone porosity vs HV-DCS]

1ma, He divers dove and backfloated and did not hyperventilate (as indicated by dense bones). Alternating partners diving/backfloating w/o HV produces no DCS N2 accumulation.

3.5ka Micronesian divers dove and boated and likely did hyperventilate (see Tarawa disease), possibly getting bent/DCS producing joint pain and possibly increased porosity in leg bones eventually, (as indicated by porous bones in their fossils derived from low Cu/Fe nutrients, but possibly also due to DCS). Individual or Unison diving/boating w/HV may produce DCS/bends/Tarawa disease.