A study at False Bay, San Juan Island, Washington reveals that the burrows of Abarenicola pacifica are rarely, if ever, anoxic.  Lowest values for oxygen concentration recorded in the burrows is about 0.9ml O₂ ^. l^-1 at low tide, with values rising to 2-3ml O₂ ^. l^-1 at high tide.  If worms are kept in anoxic seawater they survive for at least 3d.  May 1972 Biol Bull 142: 71.

NOTE  well aerated seawater contains about 6-7ml O₂ ^. l^-1 at 20^oC

A study of osmoregulatory capabilities in lugworms Abarenicola pacifica in Coos Bay, Oregon shows that over a salinity range of  29-97% seawater the species is an osmoconformer.  Note that the coelomic fluids are slightly hyperosmotic to the medium by about 5%.  Laboratory tests on survival in low salinities suggest that A. pacifica is unlikely to survive more than brief exposure to salinities below 50%, and this may represent the critical lowest interstitial salinity able to be tolerated in the estuary.  Oglesby 1973 Biol Bull 145: 180.

NOTE  100% oceanic seawater is equivalent to 560mM Cl^- or 35‰