Ruttenberg, K. C. Woods Hole Oceanographic Institution, kruttenberg@whoi.edu
Monaghan, E. C. Woods Hole Oceanographic Institution, emonaghan@whoi.edu
Keon, N. E. Massachusetts Institute of Technology, nkeon@whoi.edu

 
SEASONAL IMPORTANCE OF DISSOLVED ORGANIC PHOSPHORUS AS A NUTRIENT-P SOURCE IN A COASTAL MARINE SYSTEM: THE EEL RIVER SHELF
 
A seasonal study of water column nutrient chemistry in a northern California coastal system, the Eel River Shelf, indicates that Dissolved Organic Phosphorus (DOP) constitutes an important fraction of the total dissolved phosphorus inventory in both spring and summer. However, there are important seasonal differences. In the spring, Dissolved Inorganic Phosphorus (DIP) concentrations typically exceed DOP concentrations throughout the water column. Summer profiles, in contrast, show surface water DOP concentrations as much as six times higher than DIP concentrations. These DOP concentration maxima typically coincide with a maximum in chl-a, DIP concentrations near detection limits, and the presence of alkaline phosphatase (APase) activity. The presence of APase activity, an inducible enzyme in algae and bacteria whose presence indicates phosphate limitation, suggests that algae are hydrolyzing DOP to form DIP in order to satisfy their nutritional phosphate demand. The same stations which in summer display higher DOP than DIP and high chl-a often show high surface water ammonia concentrations, as well, resulting in ratios of Dissolved Inorganic Nitrogen (DIN) to DIP (e.g. DIN:DIP) which exceed the Redfield Ratio, also consistent with a seasonally phosphate-limited system.
 
Day: Thursday, Feb. 4
Time: 04:15 - 04:30pm
Location: Sweeney Center
 
Code: SS33TH0415S