Initially a marine fisheries biologist; changed to public health researcher (all that fisheries population dynamics stuff swims right over to epidemiology!); federal grant reviewer (research methodology expert) for multiple US government agencies. My son lives in Philippines so I am interested in supporting research there.
I think I remember learning that different bodies of water have salinity signatures, with colder (deeper) water having higher salinity. pH may have been part of the signature, as well. Are you seeing changes in the signatures with acidification and warming temps over time?