EOS 311 – Graphing Report, Nov. 14 2014
Prepared by Landon Mutch, 764791
An analysis of the data collected during the Strickland cruise
The data presented in the following figures and tables was collected from Sept. 29 – Oct. 6, 2014,
aboard the Strickland from the locations shown in Figure 1. There were three more locations to the
North in Sansum Narrows which will not be included here so that the other three regions – Haro Strait
(H1, H2, H3), Saanich Inlet (S3, S4, S4.5), and Satellite Channel (S5, S6, S9, see Figure 1) – may be more
thoroughly covered. Each Station was sampled twice over the course of the week; however, throughout
this report the average values of the various data samples will be calculated to minimize the effects of
potential “patchiness” in the data and to hopefully smooth out the data to better represent the general
trends of each station location. This averaging seemed to work well across the entire data set, and from
here onwards the analysed data for each measurement type at each station will be taken to be the
average of the two measurements taken at that station.
Part 1: Figures and tables
Figure 1. Map of the study area and station locations: Haro Strait shown in blue, Saanich Inlet
shown in green, and Satellite Channel shown in red.
Station
H1a
H1b
H2a
H2b
H3a
H3b
S3a
S3b
S4a
S4b
S4.5a
S4.5b
S5a
S5b
S6a
S6b
S8a
S8b
Region
Haro Strait
Haro Strait
Haro Strait
Haro Strait
Haro Strait
Haro Strait
Saanich Inlet
Saanich Inlet
Saanich Inlet
Saanich Inlet
Saanich Inlet
Saanich Inlet
Satellite Channel
Satellite Channel
Satellite Channel
Satellite Channel
Satellite Channel
Satellite Channel
Date
30-Sep-14
03-Oct-14
30-Sep-14
03-Oct-14
30-Sep-14
03-Oct-14
29-Sep-14
04-Oct-14
29-Sep-14
04-Oct-14
29-Sep-14
04-Oct-14
01-Oct-14
06-Oct-14
01-Oct-14
06-Oct-14
01-Oct-14
06-Oct-14
Latitude
48.715
48.716
48.677
48.676
48.629
48.623
48.592
48.592
48.638
48.640
48.669
48.669
48.716
48.716
48.753
48.753
48.742
48.743
Longitude
-123.255
-123.257
-123.276
-123.273
-123.255
-123.252
-123.500
-123.500
-123.500
-123.500
-123.500
-123.500
-123.460
-123.461
-123.308
-123.309
-123.394
-123.395
Depth (m)
247
196
169
190
162
165
222
220
177
188
155
152
114
112
128
120
82
52
Table 1. Sample dates, GPS
coordinates, and depths for
the various stations with ‘a’
denoting the first sample
taken at a station and ‘b’
denoting the second sample
taken at a station.
At all stations, measurements were taken twice over the course of the week with the CTD
(Conductivity/Temperature/Depth sensor, cSeaBird SBE19) tool to record temperature, salinity, oxygen,
density, fluorescence, and irradiance levels from the depths shown in Table 1 to the surface at each
station. And as mentioned previously, the two measurements (a/b, Table 1) for each data set were
averaged by depth interval (1m) to combine the data sets into one date set with the intent of
homogenizing the data presented in the following figures.
The temperature profile from all regions (Figure 2a) shows that the surface temperatures are warmest
with a sharp decline to about 10m. From Figure 2a we can see that Saanich Inlet has a stratified column
of water, with a warm layer (13.5oC) on top which decreases rather steeply (relative to the other
regions) from the surface to 10oC at 80m; then at 80m there is layer of water which very steeply
decreases by ~1oC and then increases again to around 9.5oC at 90m; and finally the temperature
gradually decreases to a uniform 9oC at the bottom. The other regions do not show this stratified profile
in temperature but rather gradually decrease from roughly 11.5oC at the surface by a few degrees at the
bottom, with stations S5 and S8 slightly warmer than the other Haro Strait and Satellite Channel
stations.
The oxygen profiles for all regions (Figure 2b) show a rapid rise in oxygen levels from roughly 3ml/L at
the surface by a 1-2ml/L at 10m depth – with Saanich Inlet showing the most pronounced rise in oxygen
concentrations. At the Haro Strait and Satellite Channel stations the oxygen gradually declines from 10m
to approximately 2.5ml/L at the bottom. At the Saanich Inlet stations the same stratification pattern
shown in temperatures is reflected in oxygen levels, with a “bump” between 80-90m below which
oxygen levels decrease to completely anoxic conditions of 0ml/L below 170m at stations S3 and S4 and
down to 0.5ml/L at the bottom (150m) of S4.5.
Figure 2. Averaged temperature (a) and oxygen (b) depth profiles as measured with the CTD
(Conductivity/Temperature/Depth sensor, cSeaBird SBE19) at all stations during the Strickland cruises.
(a)
(b)
The salinity profiles for all stations (Figure 3a) show a sloped increase of 1-2PSU from the surface to the
bottom, with stations H1 and H2 displaying the broadest range and increasing the most rapidly in
shallow waters from ~30.25PSU to ~32PSU near the bottom. The density profiles for all stations (Figure
3b) mirror the salinity trends extremely closely which suggests the two properties are closely related.
The fluorescence profiles for all stations (Figure 4a) are rather “noisy”, but generally (excepting H1 and
H2 which show a steady, sloped decline from the surface to depth) show an increase in fluorescence
from the surface to roughly 10-30m and a sloped decline in levels with increasing depth past ~25m.
Saanich Inlet’s slope is the steepest of the regions which decreases rapidly to a fairly steady 0.25mg/m3
at 60m depth (S3 actually increases ever so slightly with depth), while the other regions show a more
moderate decreasing slope to a more “noisy” fluorescence of 0.5mg/m3.
Figure 3. Averaged salinity (a) and density (b) depth profiles as measured with the CTD
(Conductivity/Temperature/Depth sensor, cSeaBird SBE19) at all stations during the Strickland cruises.
(a)
(b)
In comparison to fluorescence, the irradiance (PAR/irradiance, Figure 4a) profiles for all regions show
very “smooth” declining slopes that converge at 0μEinstein/m2sec1 at 25m depth, with stations H3 and
S6 increasing slightly from surface to ~5m before decreasing.
Concentrations of the nutrients nitrate (Figure 5a), phosphate (Figure 5b), and silicic acid (Figure 5c)
were measured twice at each station and the average of each calculated. The combined bar charts were
chosen to represent the data in Figure 5 instead of depth profile line charts (as used for Figures 2 – 4)
due to the discrete nature of the data – because the data is not continuous it is important not to
misrepresent the possible trends (or lack thereof) in concentrations, and the stacked bar graphs make it
much easier to compare the relative concentrations of nutrients across the various stations and depths
while also representing the discontinuities in the data (at 60, 70, 80, and 90m intervals, excepting S5).
Figure 4. Averaged fluorescence (a) and irradiance (b) depth profiles as measured with the CTD
(Conductivity/Temperature/Depth sensor, cSeaBird SBE19) at all stations during the Strickland cruises.
(a)
(b)
For example, in Figure 5a we can see that nitrate concentrations tend to increase from the surface to
100m in Saanich Inlet and Haro Strait, after which point they decrease towards the bottom; while in
Satellite Channel nitrate concentrations tend to increase to about 50m and then slightly decrease
towards the bottom. Phosphate and silicic acid concentrations (Figure 5b) stay very uniform for Satellite
Channel and Haro Strait all through the water column, whereas in Saanich Inlet phosphate and silicic
acid concentrations increase rather dramatically from the surface to the bottom. The actual
concentrations may also be measured from the charts presented in Figure 5, but will not be mentioned
here as it is more important for our purposes to display the similarities or differences between the
various regions and particular depths.
Figure 5. Averaged nitrate (a), phosphate (b), and silicic acid (c) profiles determined from samples
acquired by submerged Niskin bottles at discreet depths during the week of Strickland cruises. Samples
were analysed in the EOS 311 lab during subsequent weeks and combined to create the data set used in
this figure.
(a)
(b)
(c)
Figure 6. Averaged chlorophyll a concentrations measured in mg/m3 and displayed here as percentages
of total chlorophyll measured from samples obtained with Niskin bottles at specific depth intervals across
all stations. Also shown are comparison percentages of total chlorophyll concentrations for all depths by
station (black trend line). This format allows for straight forward comparisons between regions, stations,
and depths, but omits actual concentrations to highlight the regional changes in chlorophyll a.
Figure 7. Averaged zooplankton biomass measurements obtained from samples collected with a 60cm
diameter SCOR net equipped with 256μm mesh and a closing attachment from separate shallow (50-0m)
and deep (100-50m) tows. The tows were conducted during the Strickland cruises, and the samples were
analysed in subsequent weeks in the EOS 311 lab and combined into the data set displayed here.
Total chlorophyll a concentrations (Figure 6) can be seen to smoothly decreasing from the surface to
40m across all regions (Figure 6, black line); however relative proportions of chlorophyll a
concentrations are certainly not evenly distributed across regions. Figure 6 shows that relative
proportions of chlorophyll a steadily increase with depth at Haro Strait to 40m and in Satellite Channel
to 20m and rapidly decline from the surface to only around 5% of the total chlorophyll a concentration
at 40m.
The total zooplankton biomass and distribution of zooplankton communities were found by conducting
two net tows at each station – one shallow (50-0m, Figures 7 and 8) and one deep (100-50m, Figure 7
and 9) – which were both repeated twice at each station and the appropriate tows averaged as with the
other measurements. All the samples were split in half: one have was strained and analysed for total
biomass (Figure 7) and the other was preserved in a 5% by volume formalin solution for later analysis of
community distribution (Figures 8 and 9).
Zooplankton biomass was particularly high at H1 and H2 in the shallow waters of Haro Strait and at
stations S5 and S6 in the deep waters of Satellite Channel and was quite low, particularly in the shallow
waters, in Saanich Inlet (Figure 7).
Figures 8 and 9 both show that copepods are by far the most abundant species of zooplankton caught in
the nets across all regions, representing 70% of the total number of zooplankton from the surface down
to 50m and around 95% of the total zooplankton caught from 50-100m. Larvaceans, amphipods, and
euphasids appear to be the next most common species of zooplankton. While there appears to be some
other trends in community distribution shown (such as uneven distribution of jellies at different depths
in Saanich Inlet and Satellite Channel), these features may merely be a result of “patchiness” in
distribution and it is difficult to draw too many conclusions from such a small data set over a limited
time span of one week.
Figure 8. Averaged distribution of zooplankton community composition from samples collected by
shallow (50-0m) net tows during the Strickland cruises. Samples were immediately preserved in formalin
solution (5% by volume) and later analysed (by counting of organisms in representative samples) in the
EOS 311 lab during subsequent weeks. Results are shown here as percentages of total counts by species,
an average across all stations (total bar), and a percentage of total organisms (black line).
Figure 9. Averaged distribution of zooplankton community composition from samples collected by deep
(100-50m) net tows during the Strickland cruises. Samples were immediately preserved in formalin
solution (5% by volume) and later analysed (by counting of organisms in representative samples) in the
EOS 311 lab during subsequent weeks. Results are shown here as percentages of total counts by species,
an average across all stations (total bar), and a percentage of total organisms (black line).