Shelter
Shelter inlet is located on the west coast of Vancouver Island in northern Clayoquot Sound between Sydney and Herbert Inlets. This inlet borders the north coasts of Flores Island and Obstruction Island. The mouth of Shelter Inlet connects to Sydney Inlet at the northernmost part of Flores Island. Two small passages, Sulpher and Hayden, connect Shelter inlet to Miller Channel on either side of Obstruction Island. Miller Channel runs north to south and connects to Herbert Inlet. There are several freshwater sources that enter Shelter Inlet. The Megin River and Watta Creek at the head of the inlet are the largest.
Shelter inlet is 10 nautical miles long, with a mean width of 0.7 nautical miles, a mean mid-inlet depth of 80 meters, maximum depth of 175 meters and outer sill depth of 25 meters.
A fish farm is located in Dixon Bay and is owned by Cermaq. It is one of their 26 ocean-based farms.
Station Map Shelter Inlet
Shelter Inlet had a total of 9 sampling stations (72, 73, 74, 75, 76, 77, 78, 79, 80) from which this data was collected.
Sampling Conditions
Atmospheric conditions at Tofino Airport on sampling date (September 11, 2015)
On the day of sampling, there was no precipitation and it was a relatively warm day with temperatures ranging from 14 to 24 degrees C. Air pressure reached the max of 1016 mb around 11:30 am and the low of 1013 mb around 8:00 pm. Wind speeds varied throughout the day reaching the daily low of 1 km/h multiple times and the high of 13 km/h at 3:00 pm and 6:00 pm.
Tides
On the day of sampling, the tide reached a low of ~0.75 m and a high of ~3.25 m. These were actually among the lowest low tides and highest high tides in the days before and after the sampling date.
Nutrients
The following nutrient maps show the distribution of nitrates, phosphates, and silicates at the surface and bottom of the inlet.
Nitrate (NO₃)
Surface
Nitrate concentrations at the surface are greater towards the mouth of the inlet.
Bottom
Nitrate concentrations at the bottom of the inlet are consistent from the head to the mouth and found in greater concentrations than at the surface.
Phosphate (PO₄)
Surface
Phosphate concentrations at the surface are slightly higher toward the mouth of the inlet.
Bottom
Phosphate concentrations at the bottome of the inlet are greater than at the surface but decrease closer to the mouth.
Silicate (Si(OH)₄)
Surface
Silicate concentrations at the surface are fairly consistent but highest at station 78.
Bottom
Silicate concentration at the bottom are greater than those at the surface and consistent across the inlet.
Water Properties
Temperature
Tempertures ranged from about 9-20 degrees C. The inlet was warmer in 2015 than in 2013 by .5 degree C at the bottom and 1-1.5 degrees C in the top 40 meters. There is a greater level of stratification across the inlet than in 2013. These trends are consistent with nearby Herber and Sydney Inlets.
Salinity
This inlet is salty with the salinity only falling below 28 PSU in the top ~5 m of water with a strongly stratified layer of freshwater at the surface. Salinity does increase with depth and is fairly consistent from the mouth to the head of the inlet. Syndey inlet also reaches a maximum salinity of 32 PSU but nearby Herbert inlet is not quite as salty. Shelter inlet was slightly less salty in 2013, reaching a maximum of 31.5 PSU.
Density
Density ranges from 15-25.25 kg/m³ and reaches its maximum below 120 meters. Consistent with the temperature and salinity choropleth maps, there is a highly stratified layer at the surface across the entire inlet where density is at its lowest. Density in 2013 is similar but there is a denser layer present in the deeper part of the inlet in 2015.
Dissolved Oxygen
Dissolved Oxygen is more evenly distributed across the inlet in 2015 compared to 2013. Like Sydney inlet, it starts to become aneoxic below 60 meters of depth. As expected, the dissolved oxygen is higher near the surface where productivity is highest.
Fluorescence
Fluorescence is an indication of biological productivity and is expected to be higher at and near the surface. Like both Herbert and Sydney inlets, there was little productivity in Shelter Inlet in 2015, much less than in 2013.
Transmissivity
Transmissivity shows where solid particles are present in the water. Transmissivity was higher in the inlet overall in 2015 than in 2013 however, there was a lower percentage across the surface of the inlet in 2015. This is consistent with the 2015 data for Sydney Inlet. There are areas of lower transmissivity along the bottom of the inlet which could be from kicked up sediments.
Page developed by Jessica Wolford