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Drift Card Study
Overview
This study is intended to mimic the dispersal patterns of non-native Spartina seed by releasing floating ‘drift cards’ at selected locations within the Bay and tracking where the cards are found. This will help us to better understand where Spartina might crop up in the future. Spartina dies down the ground each fall/early winter. The stems break off and form large mats (called wrack), which float with the tides on the water surface. Wrack may carry Spartina seed – which can survive in wet, cold, salty conditions (like those found in Bay waters) for periods of one year. If we can find the “hot spots” for where seed is drifting, we will be able to identify high-risk areas where we want to concentrate our future monitoring work. The first round of drift cards involved three releases at each of seven sites in spring and summer 2007. The letters (A-G) identify the sites and the numbers (1-3) indicate which release date. For example, at Site A, there were three separate releases of 50 cards each, so the identifying group code would be A-1 for the first release, A-2 for the second and A-3 for the third. To gather additional information, a second round of drift card releases commenced in December 2007. As before, letters (H-N) identify the locations and the numbers mark whether the card came from the first, second or third batch of cards dispersed at that site. (See below for exact release dates.)The cards are released individually at each marsh site — flung, dropped, or tossed into the open water, taking advantage of outgoing tides. Public volunteers who report the locations where they find the cards are a critical part of our drift card study. Your efforts directly enhance the effectiveness of ISP’s Control Program. From the information gathered in this study, staff is developing a database and map of the distribution of cards throughout the Bay. Several cards released from Creekside Park, Corte Madera Creek traveled many miles to the outer coast. Many of the cards released at the West Bay sites of Colma Creek and Bair Island traveled southeast, crossing the entire Bay. One interesting deposition spot from multiple release sites was the USFWS Don Edwards National Wildlife Refuge near the Dumbarton Bridge.
Locations
Frequently Asked Questions
1) What should I do with the card(s)? After you have shared the location where you found the card, please feel free to either throw the cards away or to keep them.
2) When was my card released?
The number following the release location letter on your card indicates the release date of your particular card. For example, the first cards were released in March 2007. The second set of releases (with cards numbered 2) occurred in April. The third and last set was dispersed at various dates from late May to mid-August 2007.
The first batch of cards from each location was released in December 2007-January 2008. The specific dates are: Dec. 19 – I-1 The second release of cards from these sites occurred in February and March. The specific dates are: Feb. 18 – H-2, K-2 3) How long is this study? The second round of releases began in December 2007 and will continue into summer 2008. The preliminary results have been very informative, so an additional round is planned for autumn 2008. People may be finding cards up to a year after the initial release. So, please contact us with any additional cards you find at (510) 548-2461 or www.Spartina.org 4) Aren’t you contributing trash to the Bay? While these drift cards are man-made objects, they are fully biodegradable and constructed to degrade within a short period of time. They are made of sustainably farmed mahogany plywood and coated with non-toxic, lead-free paint and ink. The cards are considered a very low-impact way to study surface currents in oceans around the world. This method of study has helped to model potential oil spill scenarios, collection points for garbage, and now, the potential spread of invasive species. Click the"back" button of your browser to return to your form. |
