1. ESCI 491: Eelgrass community function and response to sulfide Fish Team: Brian Maskal, Mattie Michalek, Elizabeth Orta Photosynthesis and alkalinity team: Jennifer Dunham and Chloe Nelson Sulfide and eelgrass distribution team: Angela Gossom, Sean Wu, Matthew Kneipp Sulfur in leaf and root team: Jennifer Hartke, Rachel Blyth

2. Eelgrass as fish habitat Questions: Which species of fish depend upon eelgrass habitat? Do juvenile salmon use eelgrass as habitat? Methodology: Sample Site: Mud Bay, Bellingham, WA Seined in eelgrass and non-eelgrass sites

3. Fish species observed

4. Juvenile salmonids Eelgrass site 1: 1 Coho Eelgrass site 2: 1 Coho Non-eelgrass site 1: 1 Steelhead Non-eelgrass site 2 (in cove): 0 salmonids Salmonids found in eelgrass and non-eelgrass habitats. Coho only found in eelgrass beds On average, more species and more individual fish observed in eelgrass beds Very small sample size

5. Eelgrass photosynthesis, oxygen, and alkalinity production Questions: What is the rate of net photosynthesis in eelgrass? How does the presence of eelgrass affect alkalinity production? Methods Incubated sediment cores with and without eelgrass Measured dissolved oxygen, DIC, and alkalinity over time

6. Observations – Dissolved oxygen increased EelgrassSediment Day Night

7. Observations – DIC decreased EelgrassSediment Net photosynthesis rate: 3 mg C shoot -1 d -1, or 0.1 g C m -2 d -1 Day Night

8. Observations – Alkalinity flux Not much change in alkalinity Day Night

9. Relationship between eelgrass density and pore water sulfide Questions: How does eelgrass density vary with pore water sulfide concentration? Methods Sampled eelgrass in two locations: Padilla Bay and Hood Canal Measured pore water sulfide: Used sippers to sample, preserved samples in SAOB, measured sulfide using an ion-selective electrode

10. Results – Eelgrass vs. sulfide inventory Padilla Bay

11. Results – Eelgrass vs. sulfide inventory Hood Canal

12. Sulfur in eelgrass leaves and roots Questions: Does S in eelgrass reflect pore water sulfide, eelgrass density, or water-column oxygen? Methods: Collected eelgrass leaves and roots from Padilla Bay and Hood Canal Measured S using an elemental analyze

13. Results: Average %S and eelgrass density

14. Results: %S in leaves vs. pore water sulfide Not plotted – one data point from Hood Canal at 0.9 %S 0.9%

15. Results: Eelgrass density vs. %S in leaves

16. Summary and interesting observations Lots of fish in the Chuckanut Bay eelgrass beds but few salmonids Rates of photosynthesis derived from DIC measurements similar to rates determined by 14 C. Eelgrass does not have a large affect on alkalinity production Eelgrass density does not vary with pore water sulfide, nor does sulfide intrusion into leaves in Padilla Bay and Hood Canal One shoot in Hood Canal had very high levels of S in leaves – What conditions lead to sulfide intrusion?