1. Salinity, dissolved oxygen, and nutrient concentrations in Oyster Pond, Falmouth, Massachusetts Karen Bishop and Michael Perret: Marine Ecology, Prof. Ivan Valiela www.karenrinaldogallery.com/ oil.html

2. Study Questions: 1)What are the current horizontal and vertical distributions of salinity, O 2, and nutrients in OP, and nearby SP? 2) What do these distributions tell us about the exchange of salt and nutrients? 3)Is growth of primary producers limited by N or P in OP and SP? 4)Were there any important changes between salinity, oxygen, or nutrients between 2001 and 2004 in OP?

3. Nitrogen – Ammonium, Nitrate (NH 4, NO 3 ) Phosphorus- Phosphate (PO 4 ) Dissolved Oxygen (O 2 ) Salinity (ppt ) Eutrophication and Variables of Interest

4. Experimental Procedure/Data Collection Mid- and high-tide collection Surface to bottom measurements at 1 meter increments Recorded temperature and O 2 using YSI probe; record salinity using refractometer; collect water samples for nutrient analysis Sample bottles filtered and frozen for measurement with “ Lachat ” auto-analyzer Standard spectrophotometric methods Bathymetric profiles of all 6 variables for OP and SP

5. Oyster Pond and Salt Pond transect points Salt PondOyster Pond

6. Salinity (ppt) 0 0 2 4 6 Depth (m) 0 1 2 4 5 0 0 0 1-2 3 6-8 12 3 32 25 27 26 Higher at SP 3 OP SP -transect pts & depth (dots) -averages -max. depth OP- 6.5m SP- 4m -anoxic zone NS.

7. O 2 (mg l -1 ) 0 2 4 6 Depth (m) 0 1 2 3 4 5 0 0 9-11 6 3 1-2 8 9 3-5 Similar OP SP NS

8. NO 3 (µM) 0 0 1-2 2 ≤ 1 1.5 <1 1 2 1-2 0 3 4.5 5.25.5 Generally higher at SP 0 Depth (m) 0 2 4 6 0 1 2 3 4 5 OP SP NS 5

9. NH 4 (µM) 0 0 0 1-2 4-5 3 5-6 16 22 50-110 2 4-7 8 17 1-2 7 2-3 4-5 55 8-10 5 1 More variation and higher in deep water at OP Depth (m) 0 2 4 6 0 1 2 3 4 5 OP SP NS

10. PO 4 (µM) 0 0 0 0 0-.6 3 14-21 4 1 0-.6 Similar overall, but higher in deep water in OP Depth (m) 0 2 4 6 0 1 2 3 4 5 OP SP NS

12. Oyster PondSalt Pond Salinity (ppt)1-2 (12.5)25 (27) Dissolved Oxygen (mgL -1 ) 9-11 (1.4)8 (3) Nitrate µM1 (0)3 (0) Ammonium µM1-2 (107)4-5 (55) Phosphate µM0-.6 (21)0-.6

13. -phosphate concentrations low, salinities above 10ppt usually N-limited

14. Oyster Pond Transect Points 2004 points2001 points

15. 2004 OP 2001 to 2004 Comparison Plots

16. Conclusions Comparison of Oyster Pond to Salt Pond - no difference in dissolved oxygen - lower nitrate, ammonium, salinity in OP - higher phosphate (only at depth) in OP Limiting nutrients -Both nitrogen and phosphate are limiting in OP and SP Interannual difference in Oyster Pond - no difference in salinity or dissolved oxygen - lower nitrate than 2001 - higher ammonium and phosphate (only at depth) than 2001

17. Acknowledgments Oyster Pond Watershed Residents Jen Bowen & Ivan Valiela The Fish Group Boston University Marine Program