Distribution and Species Composition of Biofilm in the Fraser River Estuary, Vancouver, British Columbia
Presentation Abstract
Biofilm is recognized as ecologically important habitat in the Fraser River Estuary due to its foraging value for migratory shorebirds. Areas of biofilm have been noted at Roberts Bank, where biofilm occurs across 120 ha in the upper intertidal zone. In 2013, hyperspectral remote sensing techniques were used to map biofilm across Roberts Bank, identifying a total area of 325 ha, including 160 ha of previously unknown biofilm in close proximity to the Fraser River. Groundtruthing data conducted during the mapping indicated a high confidence in delineating biofilm-dominated sediments. The application of a chlorophyll a algorithm identified the highest densities in sheltered habitat in the upper intertidal zone with lower densities occurring in exposed habitat.
Sediments within the identified biofilm areas were sampled for microphytobenthic composition and biomass over three seasons; spring, summer, and winter. The overall microphytobenthic community was dominated by Nitzschia spp. (33%), Navicula spp. (21%) and Achnanthidium spp. (20%). Spatially, biofilm in close proximity to the Fraser River possessed a lower abundance of marine-influenced genera as well as lower biomass, as measured by photopigment and carbohydrate densities. Seasonally, microphytobenthic composition changed towards a more diverse community from spring, through to summer and winter. However, peak biomass levels occurred in the spring and summer compared to the winter.
Assessment of physical and chemical data collected from the same sampling locations indicated a positive relationship between biofilm biomass and salinity, while a negative relationship was observed with coarse sediment grain size. This study provides the first detailed mapping and biological description of biofilm across Roberts Bank and highlights the influence of freshwater flows to the distribution, composition, and biomass of estuarine biofilms.
Session Title
General Habitat Topics
Conference Track
Habitat
Conference Name
Salish Sea Ecosystem Conference (2016 : Vancouver, B.C.)
Document Type
Event
Start Date
2016 12:00 AM
End Date
2016 12:00 AM
Location
2016SSEC
Type of Presentation
Oral
Genre/Form
conference proceedings; presentations (communicative events)
Contributing Repository
Digital content made available by University Archives, Heritage Resources, Western Libraries, Western Washington University.
Subjects – Topical (LCSH)
Biofilms--British Columbia--Fraser River Estuary
Geographic Coverage
Fraser River Estuary (B.C.); Salish Sea (B.C. and Wash.)
Rights
This resource is displayed for educational purposes only and may be subject to U.S. and international copyright laws. For more information about rights or obtaining copies of this resource, please contact University Archives, Heritage Resources, Western Libraries, Western Washington University, Bellingham, WA 98225-9103, USA (360-650-7534; heritage.resources@wwu.edu) and refer to the collection name and identifier. Any materials cited must be attributed to the Salish Sea Ecosystem Conference Records, University Archives, Heritage Resources, Western Libraries, Western Washington University.
Type
Text
Language
English
Format
application/pdf
Distribution and Species Composition of Biofilm in the Fraser River Estuary, Vancouver, British Columbia
2016SSEC
Biofilm is recognized as ecologically important habitat in the Fraser River Estuary due to its foraging value for migratory shorebirds. Areas of biofilm have been noted at Roberts Bank, where biofilm occurs across 120 ha in the upper intertidal zone. In 2013, hyperspectral remote sensing techniques were used to map biofilm across Roberts Bank, identifying a total area of 325 ha, including 160 ha of previously unknown biofilm in close proximity to the Fraser River. Groundtruthing data conducted during the mapping indicated a high confidence in delineating biofilm-dominated sediments. The application of a chlorophyll a algorithm identified the highest densities in sheltered habitat in the upper intertidal zone with lower densities occurring in exposed habitat.
Sediments within the identified biofilm areas were sampled for microphytobenthic composition and biomass over three seasons; spring, summer, and winter. The overall microphytobenthic community was dominated by Nitzschia spp. (33%), Navicula spp. (21%) and Achnanthidium spp. (20%). Spatially, biofilm in close proximity to the Fraser River possessed a lower abundance of marine-influenced genera as well as lower biomass, as measured by photopigment and carbohydrate densities. Seasonally, microphytobenthic composition changed towards a more diverse community from spring, through to summer and winter. However, peak biomass levels occurred in the spring and summer compared to the winter.
Assessment of physical and chemical data collected from the same sampling locations indicated a positive relationship between biofilm biomass and salinity, while a negative relationship was observed with coarse sediment grain size. This study provides the first detailed mapping and biological description of biofilm across Roberts Bank and highlights the influence of freshwater flows to the distribution, composition, and biomass of estuarine biofilms.
