Case Studies - Coastal Lagoons: Ecosystem Processes and Modeling for Sustainable Use and Development - page 374

As a result, waters in the lagoon show little vertical density stratification except
perhaps during the ice-melting period (April). Finally, winds are predominant from
the southwest-northeast axis, that is, along the major axis of the lagoon. 11

9.2.3 W IND -D RIVEN C URRENTS : O BSERVATIONS

A large-scale multidisciplinary field experiment was carried out in GEL during the
summers of 1988 and 1989. 15,16 The objective was to study the impact of increasing
mussel aquaculture on the biological production of the lagoon. Aanderaa current meters
and tide gauges were moored exactly 1 m above the bottom from May 5 to May 20,
1989 at several stations in the lagoon, including C1, C6, C10, C12, and C11 in the
deep basin (Figure 9.2.2). Mooring C1 outside the inlet was fitted with a second current
meter near the surface that was left in the water for a longer period of time. Divers
performed daily inspections of all moorings in order to remove possible rotor contam-
ination by drifting algae. Conductivity and temperature profiles were obtained at
several locations in the lagoon over neap and spring tidal cycles. Finally, winds and
atmospheric pressure were measured at Grindstone (Figure 9.2.2). Analysis of the
complete current and sea-level data set has been reported elsewhere. 11,16 It was shown
that tidal currents reach speeds above 0.5 m/s at the lagoon entrance and in the shallow
regions to the west, while in the deeper basin, to the right of the navigation channel,

N

62 ° 00 ′ 61 ° 40 ′

L1

47 ° 30 ′

L9

C11

L2

C12

47 ° 20 ′

Grindstone

47 ° 35 ′

0 15 km C10

C6

L1 C1

Current meter
Tide gauge
Meteorological station

47 30

° ′

0 5 km

61 ° 40 ′ 61 ° 30 ′

FIGURE 9.2.2 Positions of sea level (L1) and current (Cx) recording stations during 1989
in Grande-Entrée Lagoon in the Magdalen Islands, Gulf of St. Lawrence.