SS3.08 Application of Automated Technology to Detect Environmental Change
Date: Thursday, June 13, 2002
Time: 11:00:00 AM
Location: View Royal
 
IbarraDA, Dalhousie Univ., Halifax, Canada, dibarra@is2.dal.ca
Cembella, A, D, NRC, Halifax, Canada, Allan.Cembella@nrc.ca
Grant, J, , Dalhousie Univ., Halifax, Canada, jon.grant@dal.ca
Cullen, J, J, Dalhousie Univ., Halifax, Canada, John.Cullen@Dal.CA
 
OPTICAL MOORINGS AS A TOOL TO QUANTIFY SESTON REMOVAL BY FARMED MUSSELS
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At overstocked mussel farms, bivalve feeding may substantially deplete seston from the water column, thereby reducing mussel growth. The objective of this study was to quantify with autonomous measurements the decrease in chlorophyll concentration due to cultured mussels in Ship Harbour (Nova Scotia), an estuarine fjord with significant tidal flux. Two Tethered Attenuation Coefficient Chain Sensors (TACCS; Satlantic, Inc.), were used to measure the penetration of solar irradiance at stations inside and outside the farm. The calculated attenuation coefficient at 490 nm, Kd(490), integrated over the stratum where the mussels were concentrated (4 to 8 m), was significantly correlated with chlorophyll concentration (R^2=0.932; N=7). Measurements of salinity from a moored CTD were used to correct Kd(490) for absorption by Coloured Dissolved Organic Matter, which was correlated with freshwater input. River discharge was reduced during the study period (September-October 2001), thus only a slight improvement in the correlation between Kd(490) and chlorophyll was achieved (R^2=0.936). The results provide evidence of chlorophyll decrease (up to 75%) due to mussel feeding activity that is consistent with the existing seston-depletion models.