Herbert Inlet is located towards the middle of Clayoquot Sound. It is a fjord type estuary carved by glacial activity which gave it its deep basin and a very shallow sill its mouth. It has the most shallow sill (measuring 5 m deep) out of all the inlets in Clayoquot Sound. The deepest part of Herbert Inlet is about 140 meters deep. It's very narrow measuring about 2 km wide and 26.5 km long. Outside the mouth of Herbert Inlet is McKay Island and Miller Channel which connects Herbert with Shelter Inlet. Also across from Herbert Inlet is the Ahousat village on Flores Island. At the head of the inlet is a waterfall fed by the Moyeha River. The river is about 28 km long and forms the mainstem of the Moyeha watershed. This watershed covers about 18,200 hectares and is considered one of the few remaining pristine watersheds in Clayoquot Sound. It is situated in Strathcona Provincial Park near the head of Herbert Inlet. Quait Bay located in a hidden cove off of the inlet attracts many tourists and fishermen each year. Quait Bay can only be accessed by boat or plane. At the mouth of the inlet there are also a couple fish farms.

September 11th, 2015

During sampling it was sunny and there was no precipitation. Weather was reported to be calm throughout the day. Temperatures were between 11 and 13 degrees C until 9am then warmed up to almost 24 degrees C at 1pm and cooled down to about 14 degrees C into the evening. The station pressure rose to about 1016 mb at around 9:30am then steadily dropped in the afternoon and evening. The wind direction was N until 9 am then switched to S/SE around 11am, then W/NW after 12 pm. This pattern can be seen across all inlets in Clayoquot Sound where wind directions switch to travelling up inlets every afternoon. This is driven by the land-to-sea heat difference as the land heats up in the afternoon. Winds were calm throughout the day with speeds less than 14 km/h.

Data was collected from the Tofino-Ucluelet Airport weather station.

All nutrient types mapped showed similar trends in nutrient levels between the surface, chlorophyll max, and bottom. There were high nutrient levels at the bottom due to plankton die-off as summer came to an end. Some phytoplankton blooms may have also depleted nutrients at the surface. There were similar trends in nutrient levels in Shelter Inlet, Sydney Inlet, and Millar Channel. No nutrient data were gathered for Tofino Inlet and Bedwell Inlet in 2015 so no comparisons can be made with them. In comparison to nutrient levels in Herbert Inlet in 2013, the 2015 surface, CMax, and bottom levels were very similar across all nutrients. In 2015, the phosphate levels at the bottom were slightly higher at the head of the inlet (stations 36 and 38) than 2013.

Herbert Inlet had fairly warm temperatures ranging from about 10 to 17 degrees C. A pattern can be seen where warmer water appears to have begun flushing in from the ocean leaving warmer temperatures (about 12 degrees C) at the deepest part of the basin, and there is a remnant layer with cooler temperatures (about 11 degrees C) near the head of the inlet (between 35-65 m). The highest temperatures can be seen at the surface (around 17 degrees C). This Inlet appeared to be cooler than other inlets with similar depths such as Tofino Inlet. This is likely due to the shallow sill at the mouth of Herbert Inlet which limits the amount of ocean water entering it. In comparison to Herbert Inlet in 2013, the temperatures in 2015 were warmer overall. In 2013, the coolest temperature was 9 degrees C while in 2015 it was 11 degrees C.

Salinity increases with depth in Herbert Inlet with strong stratification. This is because of the shallow sill at the mouth of Herbert Inlet which traps water there, limiting mixing with ocean waters. It can be seen that the lowest salinity is found at the surface near the head of Herbert Inlet where freshwater is entering from Moyeha River. In comparison with Tofino Inlet, Herbert Inlet had slightly higher salinity levels (about 31 PSU). Otherwise these inlets showed similar trends in stratification. Herbert Inlet and Millar Channel also had similar trends in salinity. In 2015, Herbert Inlet appeared to have a larger layer of high salinity (31 PSU) water which extended from 30 m to 140 m deep while in 2013, it only had a salinity of 31 PSU between 100 m and 140 m deep.

Herbert Inlet is highly stratified due to freshwater input from Moyeha River at the head of the inlet and saltwater input from the ocean at its mouth. The density stratification of Herbert Inlet almost mirrors that of salinity where water is densest at the deepest depth due to high salinity levels. It shares similar density stratification patterns with Tofino Inlet and Millar Channel but is slightly denser than Tofino. Herbert Inlet in 2013 had a similar pattern in density stratification.

Herbert Inlet had the highest dissolved oxygen concentrations near the surface where phytoplankton are most productive and water is in direct contact with the atmosphere. Waters were anoxic near the head of the inlet between 30-50m deep. It is common to find anoxic waters in inlets with shallow sills because the sill prevents ocean water from flushing out old, stagnant water in the basin. Other inlets appeared to be more oxygenated because they don't have a shallow sill at their heads. Herbert Inlet appeared to be getting flushed out by ocean waters at this time where some dense, oxygenated water was able to flow over the sill and fill in the basin of the inlet, pushing old, anoxic waters up to the surface. This reflects the pattern of flushing seen in the temperature contour map for this inlet. In comparison to Herbert Inlet in 2013, both appeared to be experiencing ocean flushing at this time of year. In 2013 it seemed to have slightly higher levels in dissolved oxygen in the basin.

Herbert Inlet did not appear to be very biologically productive during the sampling period in 2015. There appears to be a small patch of fluorescence at the surface near the middle of the inlet at station 35. Otherwise the inlet had no fluorescence below the surface. Herbert Inlet in 2013 had much higher fluorescence levels at the surface than in 2015. This might be because water temperatures in 2015 were higher than temperatures in 2013. Surface temperatures in 2015 may have been outside the preferred temperature zone for some phytoplankton species. In 2013, Herbert Inlet also had high fluorescence levels at the surface in the same area (station 35).

Herbert Inlet had low transmissivity near the surface, especially near station 35 where there was a small phytoplankton bloom. At the bottom, transmissivity was also low due to suspended sediments in the water. Millar Channel showed a similar pattern in transmissivity. In Comparison to Hebert Inlet in 2013, the transmissivity patterns were very similar.

The shallow sill at the mouth of Herbert Inlet seemed to have a large effect on the parameters within it. This sill contributed to the anoxic waters found within the inlet, limiting flushing with ocean water. Herbert Inlet retained cooler temperatures than other inlets with similar depths which is likely due to the sill preventing warm ocean surface waters from flooding in. During the sampling period, Herbert Inlet appears to have started being flushed by ocean waters which can be seen in the dissolved oxygen contour map as well as the temperature contour map. In the salinity contour map, it can be seen that the sill allowed for greater salinity levels and stratification by trapping water in the inlet and limiting mixing with ocean water. Density appeared to be mostly influenced by salinity where a clear relationship can be seen when comparing the two contour maps. Transmissivity seemed to be mostly influenced by phytoplankton blooms at the surface and suspended sediments in the water column near the bottom. Herbert Inlet showed changes in some of its parameters between 2013 and 2015: water temperatures increased by about 1-2 degrees C in 2015, fluorescence levels were much lower in 2015, dissolved oxygen levels were slightly higher in 2013, and waters were more saline overall in 2015.

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