Aundi Mevoli of Baykeeper updated us on the latest findings from the recent massive algae bloom (aka Red Tide) in the SF Bay. While research into how the algae Heterosigma Akashiwo interacts with our Bay is still underway, many interesting data points came up during the talk:
- They determined that the massive fish kill associated with the Red Tide was not primarily driven by a removal of oxygen from the water as had previously been suspected. Current thinking is that the range of toxins produced by the algae afflicted the gills of the finfish, causing them to suffocate. Oxygen levels in the Bay were found to drop later in the cycle, after Sturgeon and others began washing up on our shores. In a related note, these toxins may also harm competing algae. Marina and houseboat communities reported seeing green algae die off and the water become crystal clear immediately prior to the Red Tide.
- This particular algae has two flagella, allowing it to move through the plane and up and down the water column. It is therefore very adept at finding suitable conditions both to eat bacteria and photosynthesize. In addition, it can form a cyst when conditions are not ideal. Ms. Mevoli speculates that the entire floor of the SF Bay could be covered with these cysts now - once temperatures at the bottom reach 59 degrees they will once again activate.
- In order to produce an actual toxic algae event, they need low turbidity in order to photosynthesize, warm temperatures like we usually have in late summer, and a source of nutrients. The latter are provided in large part by effluent from our sewage systems around the Bay. Mitigation strategies include water recycling to reduce the nutrient load and the creation of wetlands to help absorb these nutrients. These are both costly and intensive measures that will need political will to achieve. Aside from pressuring elected officials, Baykeeper will also be starting up a citizen science program early next year to continue to engage the community in this issue.