Understanding Complex Data: Coastal Monitoring
The Province of Nova
Scotia recognizes the importance of coastal waters, which are critical to the
prosperity and sustainability of rural and coastal communities. To bridge the
gap between science and decision making, the Nova Scotia Department of
Fisheries and Aquaculture (NSDFA) partners with the Centre for Marine Applied
Research (CMAR) to measure the environmental conditions of Nova Scotia’s
coastal waters.
The data derived from
coastal ocean monitoring is useful to many stakeholders, including:
- Scientists studying coastal species, coastal ecosystems, and climate change;
- Engineers and operators in the fisheries, aquaculture, and renewable energy industries seeking to minimize environmental impacts while maximizing economic development;
- Governments taking a data-driven approach to policy and decision making; and
- Individuals and community groups engaged in conservation or recreation.
Monitoring Nova Scotia’s Coastal
Waters
The Centre for Marine
Applied Research collects two main types of coastal ocean data at stations
throughout Nova Scotia:
- Long-term water quality data
- Current speed and direction data
The following sections give insight into
how these datasets are collected, and their application to the aquaculture
industry in Nova Scotia.
Long-Term Water Quality Data
Detailed
environmental data is vital to decision making in the aquaculture industry.
Water quality data can be used by government and industry to improve and adapt
ongoing operations as well as to inform the identification and selection of
suitable farming areas for future fish and shellfish aquaculture.
Data are collected
from sampling stations located across most counties in Nova Scotia. Approximate
station coordinates may be viewed or downloaded from the Nova Scotia Water Quality Data: Station
Locations dataset and associated map (see below) on the portal. The exact station coordinates
may change slightly as instruments are periodically retrieved, serviced, and
re-deployed.
Nova Scotia Water Quality Data: Station Locations Map
The three main types
of data collected at the long-term water quality monitoring stations are:
- Temperature (degrees Celsius);
- Dissolved oxygen (percent saturation or milligrams per liter); and
- Salinity (practical salinity units).
These measured
variables strongly influence growth, physiology, and mortality of aquatic
organisms and animals.
Sensors designed to measure
temperature, dissolved oxygen, and salinity data are deployed at targeted
depths in the water. The sensors are attached at fixed intervals to lines also referred
to as sensor strings. The sensor strings are moored with a heavy anchor weight
and suspended through the water column using a sub-surface buoy.
To ensure easy sensor
string retrieval, the deepest sensor is equipped with an acoustically-triggered
release mechanism. When triggered by a hydrophone onboard a nearby research
vessel, these acoustic release mechanisms detach from the anchor, allowing the sensor string to rise to the surface.
Each deployment may
last from 6 months to a year and data is measured by each sensor every 1 to 60
minutes. The resulting datasets are very large, containing tens or hundreds of
thousands of data points. Datasets from some locations span over 7 years of
continuous monitoring.
Temperature sensors secured at specific locations along a
sensor string in preparation for deployment
Recovering data from a retrieved temperature sensor using a
data shuttle
Long-Term Water Quality Data on the Open Data Portal
The Nova Scotia
Department of Fisheries and Aquaculture has released long-term water quality
datasets on the portal, grouped by county. The table below contains data
collected at one of the Guysborough County monitoring stations and is just a
small sample of the data released on the Open Data Portal. The associated charts
depict daily average temperature values for individual stations within
Guysborough, Shelburne, Yarmouth, and Richmond counties. The charts are
interactive and can be changed to show temperature at selected waterbodies,
stations, depths, and timeframes. Links to all of the long-term water quality
datasets and visualizations on the Open Data Portal are available here.
Guysborough County Water Quality Data
Guysborough County Water Quality Data – Daily Average
Temperature
Shelburne County
Water Quality Data – Daily Average
Temperature
Yarmouth County Water Quality Data – Daily Average
Temperature
Richmond County Water Quality Data – Daily Average
Temperature
Current Speed and Direction Data
Ocean current speed and direction data provide valuable insight for a
variety of engineering and environmental applications. Characterization of
localized water currents is essential for assessing and modelling mechanical
stresses and the potential for infrastructure damage associated with both
existing and proposed aquaculture facilities. Researchers also depend on this
data when creating ecological simulation models to predict factors such as: the
biomass that a waterbody could sustainably support; the amount and location of
fallen organic matter potentially produced by an operation; and the amount of
phytoplankton available to feed shellfish aquaculture operations in a given
area.
Acoustic doppler current profilers (ADCPs) are deployed at stations in
the coastal waters of several counties across Nova Scotia. The Nova Scotia Current Data: Deployment
Information dataset and
its associated map (see below) contain details on current meter
deployments conducted by NSDFA and CMAR between 2007 and 2024.
Nova Scotia Current Data: Deployment Information Map
The two main types
of data are collected by the ADCPs are:
- Current speed (metres/second, captured through multiple readings); and
- Water direction (degrees relative to true north).
Current speed and water direction data is collected from several
depths through the water column using acoustic doppler current profilers
(ADCPs). ADCPs rely on a phenomenon known as the Doppler effect. The ADCP
transmits ultrasonic “pings” of sound at a constant frequency into the water.
As these acoustic beams travel, sound waves ricochet off particles suspended in
the moving water and are reflected back to the instrument. Due to the Doppler
effect, sound waves bounced back from a particle moving away from the profiler
have a slightly lower frequency when they return, while a particle moving
toward the instrument sends back higher frequency waves. The difference in
frequency between these two sound waves is called the Doppler shift. The
instrument uses the Doppler shift to calculate how fast the particle and the
water around it are moving.
Once deployed, the
instrument is left to collect data for a minimum of 30 days, though instruments
may collect data for 120 days or more, depending on battery capacity and
recording configuration. A typical configuration will have the ADCP recording
water speed and direction parameters at 10-minute intervals. The data points
recorded by the instrument are the averaged result of many individual
measurements taken over the course of the recording interval.
1000 kHz,
shallow-water ADCP in a bottom mounted tripod frame prior to deployment
600 kHz ADCP in a
tripod frame being deployed from a small vessel
ADCP recovered
following a 90 day deployment
Current Speed and Direction Data on the Open Data Portal
The Nova Scotia Department of Fisheries and
Aquaculture has released current data from deployments for several counties
across Nova Scotia. The table below contains an example of data collected from
Shelburne County. The charts below depict daily average current speed at
stations in Shelburne, Digby, Queens, and Pictou counties. Links to all current
speed and direction datasets and visualizations on the Open Data Portal are
available here.
Shelburne County Current Data
Shelburne County Current Data –
Daily Average Current Speed
Digby County Current Data –
Daily Average Current Speed
Queens County Current Data –
Daily Average Current Speed
Pictou County Current Data –
Daily Average Current Speed
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