Water column stratification

P is very slowly due to water column stratification. The P depletion of water pool leads to low P content and finally limits the biological productivity of the aquatic ecosystem. 

Because of their specificity for particular bacterial groups and environmental conditions, they make excellent biomarkers. Another steroidal biomarker is gammacerane (Figure 22.19b), which has six six-membered carbon rings. It is used as an indicator of water-column stratification in marine and lacustrine deposits. 

Sinninghe Damste J. S., Kenig F., Koopmans M. P., Koster J., Schouten S., Hayes J. M., and de Leeuw J. (1995) Evidence for gammacerane as an indicator of water column stratification. Geochim. Cosmochim. Acta 59(9), 1895-1900. 

After the winter bloom, water column stratification occurs in March-April, which results in the formation of the DCM that is characteristic of the system for the remainder of the year. The stratification starts in the offshore area in the Southeast Levantine Basin and spreads from there to the north and west. In summer the DCM is typically greater than 100 m deep with the waters above it depleted in inorganic N and P but containing significant amounts of dissolved organic nitrogen and phosphorus. 

Pazos, Y. et al., Dinophysis acuminata and water column stratification, in SCOR-IOC GEOHAB Open Science Meeting HABs in stratified systems, UNESCO, Paris, 2005. 

---