Proposed Abstract Title

Natural Regeneration of Estuarine Biofilm in the Fraser River Estuary, Vancouver, British Columbia

Type of Presentation

Snapshot

Session Title

Local Stories and Results

Location

2016SSEC

Description

High densities of biofilm occur in the top 2 mm of soft fine sediments within the upper intertidal zone of estuaries. As such, biofilm is subjected to periodic physical disturbance from natural processes and is increasingly exposed to anthropogenic disturbance from shoreline use and coastal development. The natural regeneration of biofilm in the Fraser River Estuary was assessed at Roberts Bank through paired control-impact study plots. Biofilm biomass, as measured by photopigment and carbohydrate densities, was sampled immediately prior to, post, and every three to five days following a manual disturbance over a 45 day period.

Biofilm biomass at the disturbance sites was significantly lower compared with control plots for biofilm biomass parameters (chlorophyll a, fucoxanthin, and total carbohydrate) immediately following disturbance. Pairwise tests showed the biofilm biomass parameters at the disturbance sites returned to statistically similar levels as the control sites within nine days of disturbance. These results indicate biofilm to be resilient to disturbance with an ability to readily establish if optimal growth conditions occur.

A larger temporal pattern was observed within the biofilm biomass levels and the microphytobenthic community composition across all sites. Control sites did not return to pre-disturbance conditions until 28 to 32 days following disturbance. The occurrence of a 28 day pattern with peak biomass densities occurring during monthly maximum spring tides and low biomass occurring during neap tides suggests the influence of the spring-neap tidal cycle, which is known to drive estuarine mixing dynamics. Biofilm is shown to exhibit a naturally high level of variability, which should be considered during ecological assessments.

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Natural Regeneration of Estuarine Biofilm in the Fraser River Estuary, Vancouver, British Columbia

2016SSEC

High densities of biofilm occur in the top 2 mm of soft fine sediments within the upper intertidal zone of estuaries. As such, biofilm is subjected to periodic physical disturbance from natural processes and is increasingly exposed to anthropogenic disturbance from shoreline use and coastal development. The natural regeneration of biofilm in the Fraser River Estuary was assessed at Roberts Bank through paired control-impact study plots. Biofilm biomass, as measured by photopigment and carbohydrate densities, was sampled immediately prior to, post, and every three to five days following a manual disturbance over a 45 day period.

Biofilm biomass at the disturbance sites was significantly lower compared with control plots for biofilm biomass parameters (chlorophyll a, fucoxanthin, and total carbohydrate) immediately following disturbance. Pairwise tests showed the biofilm biomass parameters at the disturbance sites returned to statistically similar levels as the control sites within nine days of disturbance. These results indicate biofilm to be resilient to disturbance with an ability to readily establish if optimal growth conditions occur.

A larger temporal pattern was observed within the biofilm biomass levels and the microphytobenthic community composition across all sites. Control sites did not return to pre-disturbance conditions until 28 to 32 days following disturbance. The occurrence of a 28 day pattern with peak biomass densities occurring during monthly maximum spring tides and low biomass occurring during neap tides suggests the influence of the spring-neap tidal cycle, which is known to drive estuarine mixing dynamics. Biofilm is shown to exhibit a naturally high level of variability, which should be considered during ecological assessments.