 |
Ongoing
Projects: Benthic Community Response to Dredging in Port Sonoma Marina, Sonoma County, California Many of the projects reviewed by the Habitat Conservation Division that occur in the San Francisco (SF) Bay involve some form of dredging. However, the response of the benthic community to dredging activities, specifically the recovery rate, has never been directly determined for this area. The benthic community is a primary component of Essential Fish Habitat (EFH) providing prey items for many fish species managed by the Pacific Fishery Management Council. In order to improve knowledge of dredging impacts to the benthic community in the SF Bay, a study was undertaken to sample the benthic community prior to and after dredging events at the Port Sonoma Marina. Located at the mouth of the Petaluma River, Port Sonoma Marina lies in a deposition zone, with an estimated 0.6 cm of sediment deposited during each tidal cycle. Dredging occurs in the marina on an annual basis each winter. Salinity varies seasonally in the marina related to freshwater inflow from the Petaluma River and tidal exchange from San Pablo Bay. Inflow and salinity may affect the recruitment of benthic species after dredging. For the current study, samples are being collected monthly along four transects in the marina for 24 months. Two dredging episodes will occur during this time. The following components of the benthic community will be investigated: (1) composition (abundance, distribution, dominant species, life history phases); (2) seasonal variation; and (3) recovery from dredging. Composite benthic samples are collected using a van Veen benthic grab, washed through a standard #30 stainless steel mesh screen, and preserved in 10% buffered formaldehyde. Invertebrates will be identified to the lowest possible taxon. The results of this study will provide original data that will aid in assessing the effects of dredging on EFH in SF Bay. |
Northern California Projects: Useful Links
|
 03/11/08 |
|
