Influence of depth on salinity, temperature, organic world?

Changes in salinity, temperature and organic matter increase with depth. On the surface of the oceans, up to 200 m deep, salinity is about 35 ppm. Salinity decreases with increasing depth. The temperature also decreases with increasing depth. If the surface temperature is about 15-17 degrees Celsius, at the bottom it is 0 degrees Celsius. This is due to the poor passability of the sun’s rays to a depth of more than 200 m. And the organic world becomes impoverished with increasing depth. Aquatic inhabitants inhabit surface waters to a large extent. But this does not mean that there are no creatures at all at the bottom.