Dear WW: here's another word about ocean biostrata:
The American Heritage® Dictionary of the English Language: Fourth Edition. 2000.

stenobathic


SYLLABICATION:
sten·o·bath·ic
PRONUNCIATION:
stn-bthk
ADJECTIVE:
Limited to or able to live only within a narrow range of water depths. Used of
aquatic organisms.
ETYMOLOGY:
steno– + Greek bathos, depth + –ic.
OTHER FORMS:
steno·bath —NOUN