RV Lough Foyle LFjul91

Cruise summary report

Cruise Info. 
Ship name (ship code)RV Lough Foyle (74LG)
Cruise identifierLFjul91
Cruise period1991-07-22 — 1991-07-25
Port of departureBelfast, United Kingdom
Port of returnBelfast, United Kingdom
Objectives1. To investigate the oceanography of the western Irish Sea.

2. To determine the spatial distribution of dissolved inorganic nutrients (ammonia,
nitrate, nitrite, phosphate and silicate) and chlorophyll related phytoplankton
biomass in the western Irish Sea.

3. To undertake preliminary primary productivity experiments using a standard 14C
incubation technique.
Chief scientistRichard Gowen (Department of Agriculture for Northern Ireland)
Cruise reportRV Lough Foyle LFjul91 cruise report lf_91.pdf (0.16 MB) 
Ocean/sea areas 
GeneralIrish Sea and St. George's Channel
SpecificWestern Irish Sea and North Channel
Track chartsRV Lough Foyle LFjul91 cruise track — lf_91track.pdf (0.02 MB) 
Physical oceanography 
Water bottle stationsQuantity: number of stations = 4
Description: Water sample for salinity calibration
Subsurface temperature and salinity measurementsQuantity: number of stations = 37
Description: The vertical distribution of temperature and salinity was measured at each station using a Hydro-Bios CTD profiling system.
Transparency (eg transmissometer)Quantity: number of stations = 12
Description: Secchi depth determined
Biology and fisheries 
Primary productivityQuantity: sample litres = 5
Description: Sample collected from the ships' clean seawater supply and used to estimate primary production in phytoplankton. Water samples (60ml) were inoculated, incubated, fixed with formalin, filtered and stored until further analysis.
Phytoplankton pigs (eg chlorophyll, fluorescence)Quantity: number of stations = 37
Description: Water samples for the measurement of dissolved inorganic nutrients and estimation of phytoplankton biomass (chlorophyll) were collected from depths of 1,5,8,16,25 and 50m (or 10m above the seabed if the depth was less than 50m) at each station. At those stations where the depth of the water exceeded 50m, additional water samples were collected from depths down to approx 10m above the seabed.
Phytoplankton pigs (eg chlorophyll, fluorescence)Quantity: number of deployments = 2
Description: Fluorometer at stations 6 and 14
ZooplanktonQuantity: number of stations = 4
Description: Zooplankton hauls carried out using a Bongo net fitted with a pair of 300 micrometer mesh nets. Samples were fixed in formalin for later analysis
Incident radiationQuantity: number of stations = 2
Description: The attenuation of downwelling photosynthetically active irradiance profiles were determined using a Biospherical Instruments Inc. QSP profiling system fitted with a depth sensor