Lower Red Brook Hydrography

Environmental Monitoring II

Spring 2017

Prepared by:

Michael Coute, Aaron Sadosky, Dominic Villella, & Tanner Dailey

1. Introduction ……………………. pgs 2-7
2. Methods……………………….....pgs 7-9
3. Materials………………………....pgs 9-12
4. Graphs…………………………....pgs 13-23
5. Logger Data……………………...pgs 24
6. Case Study Graphs……………….pgs 25- 29
7. Results…………………………....pgs 30-32
8. Conclusion………………………..pgs  33-34
9. Recommendations………………...pgs 35

1. Introduction

The Lyman Reserve is a plot of land that reaches out through the towns of Bourne, Plymouth and Wareham. Red Brook is a water system that travels through the Lyman Reserve at the length of about four miles. Extending from the headwaters located at Great White Pond all the way to Buttermilk Bay. Red Brook got it’s name from it’s coloration and complexion from the iron rich soil. Red Brook is a habitat to one of the last sea-run brook trout fisheries in the country. The Trustees, Trout Unlimited, and the Massachusetts Division of Wildlife and Fisheries assist each other to protect the Lyman Reserve. Despite the continuous development of surrounding communities in the area, these organizations have build a partnership to preserve this extraordinary environment. Located in the upper Red Brook region is Century Bog. The presence of Century Bog upset water flow to the brook, efforts are being made to restore the brook to its natural state. This is the first year that the closing of the bog, and the stream will run continuously without interruption. Cranberry bogs created near tidally influenced Red Brook presented poor conditions for herring, eel, and brook trout migration. Several levees and flumes were removed as part of a comprehensive restoration plan. Restoration designs included enhancement of aquatic habitat through large woody debris installation; removal of side channel culverts; conversion of casting pools into side channel habitat; and construction of riffles and pools. These efforts will change the flow and chemistry from years past.

        The objective of this particular project at lower Red Brook is to measure salinity in parts per thousand and temperature in degrees Celsius as they change in relation to varying environmental conditions at various points along lower Red Brook. Depending on the tides, wind, and weather a halocline can be seen and a salt wedge can be mapped. Our group has the monitoring mission ahead of us to observe salinity and temperature at eight different stations along the Lower Red Brook water system. To add to our data, year round we will be using temperature and salinity loggers, which we will be deploying at station 8.  These loggers are cased in a tough material to withstand all elements, and attached is a sensor that detects temperature and salinity.  The loggers will indicate when there is an abrupt change within the water column. This can be a result from precipitation, wind mixing, tidal mixing and potentially seasonal upwelling. A salt wedge is an entity that occurs in a highly stratified estuary. Due to alternating tides throughout our visits, the halocline is located in different locations. During higher tides, a halocline can occur in areas up to station 7 and 8. During lower tides, we have determined that the halocline consistently remains between stations 2 and 3.

Figure 1: freshwater and saltwater convergence creates a wedge at Lower Red Brook 

Our expectations are that the highest concentrations of salt water will exist in the stations located closest to Buttermilk Bay and the estuary where the brook feeds into. In turn, the salt water should just about vary in low levels as the station numbers increase, with there being close to no measurable salinity further upstream of our last station: station eight. Data from years past presents this notion to hold true, with freshwater becoming more abundant upstream towards station 8. Salt levels have been found at station eight before, and is a ecological duty to see how much further upstream these salt levels can be detected. This information is important to stewards of the environment and the ecosystem itself surrounding the brook. Local organisms must be salt tolerant to survive the changing conditions. One particular species of concern is the Sea Run Brook Trout. It is an anadromous species that spends the majority of its life feeding and growing at sea. The trout then return to freshwater upstream in Red Brook to lay their eggs for spawning. The boundary between freshwater and brackish water is the determining factor for their spawning location. As any salinity intrusion within spawning grounds can be detrimental to the Sea Run Brook Trout eggs. Another aspect important to the trout’s spawning grounds is that of brook bed material. The ideal material for Sea Run Brook Trout is a gravel bed near a freshwater spring. These freshwater springs are important for maintaining a consistent temperature at all times for the eggs. As Sea Run Brook Trout typically hatch in winter months.   For fish biologists, determining the boundary between freshwater and brackish water is why the data is so important to have. Our goal is to define the relationship between the salt wedge and the tides in hopes to further paint a picture of this dynamic ecosystem.

After one semester of work, we have narrowed down where we believe the main salt wedge to be occurring. As a new addition to our project, we are adding stations 2.5  and 3.5 , in order to better understand the halocline and potential mixing in this area of the brook. Station 2.5 is downstream of station 3, just before the road bridge. Station 3.5 is in-between stations 3 and 4, at the bend in the river.

Figure 2: Overview of our site location with approximate station locations for reference. New Stations 2.5 and 3.5 are indicated in blue, while previous year's’ stations are in red.

Table 1: GPS Coordinates of all Lower Red Brook sites

Figure 3: Map of Lower Red Brook (Lyman Reserve)

II. Methods:

1. Upon arrival to Lower Red Brook, our team would put on chest waders in the parking lot, checking for holes or slices in the wader’s fabric to prevent water from entering. The chest waders would allow us to venture out into the deepest areas of Lower Red Brook to record the salinity and depth. The straps must be secure around the shoulders and properly tightened.
2. At each site, one team member would turn on the YSI salinometer, and ensure that the meter zeroed itself out prior to being placed in the water. The member using the salinometer must ensure that the meter is reading the salinity in parts per thousand and degrees in Celsius.
3. Two team members would then walk out to the deepest location at each site to collect the depth, salinity, and temperature.
4. The team member with the folding meter stick will extend the meter stick and place it in the water in the area where the salinometer probe will be reading.
5. The salinometer must be read on the bottom of Lower Red Brook to record saltwater salinity, where the water is most dense. The meter reaches an accurate reading once it stops fluctuating and pauses on a number. Although the salinometer can fluctuate constantly due to mixing at some sites.
6. The salinometer must be read at the surface of Lower Red Brook to record the freshwater concentration that is less dense than the saltwater. The meter reaches an accurate reading once it stops fluctuating and pauses on a number. Although the salinometer can fluctuate constantly due to mixing at some sites.
7. The members recording depth, and salinity will then share their results with the next team member that is standing close by who is recording all the data in our “Rite in the Rain” data notebook.
8. Steps 2 - 7 will be completed at each site at Lower Red Brook (Site 1-8).
9. As the team walks up stream and records the salinity data, we can then record where the halocline, or salt wedge is on that particular day, time, and tide level.
10. After the field work is completed, the team will return all the equipment to the MSEP lab, and the recorded salinity, and depth will be transferred from our “Rite in the Rain” data notebook into a spreadsheet for later reference.

III. Materials:

1. YSI Salinometer.

1.  This instrument measures the conductivity of the water, which converts the measurement into salinity parts per thousand. This instrument also measures the temperature of the water in degrees Celsius. The way in which the salinometer works is first it is turned on and then calibrated to zero. The purpose of this step is to ensure a reliable reading of conductivity.

1. Place sensor at the bottom of Red Brook (maximum depth), to measure conductivity and temperature.
2. Record data displayed on YSI Salinometer
3. Hold Sensor just below the water surface (20%) to measure conductivity and temperature.
4. Record data displayed on YSI Salinometer

2. Salinity & Water Level Loggers

1. Lower Red Brook Team will be deploying these at station 8.  These loggers are equipped with a sensor that detects temperature and salinity.  The loggers will indicate when there is an abrupt change within the water column. This can be a result from precipitation, wind mixing, tidal mixing and potentially seasonal upwelling.

1. Tie loggers to a cinder block at Station 8
2. Frequently bring loggers back to the lab to record data and save data onto a laboratory computer.

3. Chest/Hip Waders

1. Depending on the water levels from the semi-diurnal tides, and depth of the brook will determine which will be worn to stay dry. These will be beneficial for travelling into the brook to complete salinity and temperature tests.

1. Step into waders, and fasten straps to preferable comfort.

4. Meter Stick

1. Measure the salt/freshwater layers in the brook’s brackish waters and provide accurate depth of Red Brook during tidal cycles.

1. Place meter stick into water and determine water depth.

5. Waterproof Notebook

1. This was given to record our data. It prevents any water or weather from deteriorating the pages, thus destroying our data. To prevent any ink from smudging, we must record everything using a pencil.

1. Record the date, tide, and environmental conditions
2. Record the time of recording at each station
3. Record all data discovered at the each station.

IV. Graphs:

SPRING 2017 SEMESTER

V.  Logger Data

VI. Case Study Graphs

        A closer examination of the salt wedge that exists in the primary mixing area, between stations 2 and 4. The addition of 2.5 and 3.5 stations helps to illustrate the complexity of the salt wedge on certain moon phases and tidal situations.

VI. Results

The salt wedge exists primarily between stations 7 and 8. During the fall, observable measurements of salinity only made it past station 8, the week of November 15. This happened to coincide with an unusually high spring tide due to the stage of the moon and its proximity to the earth. This moon received attention as being the “supermoon”, the moon was the closest full moon in relation to earth since 1948. The day after the moon’s peak, we planned to be at station 8 during the high water time of 9:06.Salinity levels were at almost full strength sea water at about 26.1 ppt at the bottom of the stream. The halocline was steep, as salinity measurements at the top read 3.5 ppt. Southeast District Fisheries Manager of Massachusetts Division of Fisheries & Wildlife Director, Steve Hurley, was there with us, monitoring the activity of the Anadromous Brook Trout. He had been keeping a close eye on the brook trout the 2 previous weeks to measure breeding activity. We observed about 6 fish further upstream of station 8 with a salinity of 25.0 ppt right where the fish were spawning. We recorded this at about 9:09 (3 minutes after the high water time) at the fish tracking pipes set up by Steve and his team.  We continued to follow the salinity upstream another 50 feet and go measurements of 21.1 ppt at the bottom. After about another 100 paces, we were still reading high levels at the bottom (19.1 ppt) with relatively low levels at the top (0.4 ppt). Due to lack of access, we were unable to record any salinity levels until the site location for the ‘Middle Red Brook Team’, where levels were 0.1 ppt at both the top and bottom. On two occasions, we have seen observable levels of salinity at station 7, but then watched as levels dropped off entirely at station 8. On days closer to low water, the salinity measurements become 0.1 or unobservable as early as station 3.

Station 3 has the highest variability out of all 8 stations. We believe this can be attributed to the tidal influences, as well as the geomorphology of the stream itself. The shallow brook bends around rocks at station 4  that resemble a small rapid. From there the waters move into a deeper section of the brook as they approach the bridge at station 3. There is a high amount of mixing that occurs here, especially in between tides. For example, we took measurements on November 1 at 8:58 am, with the tide approaching high at 10:56 am. We saw fluctuations ranging from 9-29 ppt in the upper regions of the water column. This was a new moon, and the tidal influences were great, resulting in fluctuations at station 4 as well. This helps to explain the strange dip in our graph on this date. On November 29 at 8:49, the tide had just started to recede, and fluctuations were seen ranging from 10-20 ppt at the top. On December 6, we took measurements directly during the low tide. We found that the halocline existed a little less than half the distance between 2 and 3. Station 1 had fluctuating levels of mixing at the top layer on this day.

 Another example of this high mixing area can be observed on March 28, 2017. The readings at station 3 were ranging from negligible, all the way to full strength sea water. The dip in this graph is illustrative on how low the data values could be. When the mixing stopped at station 4, it is apparent that the salt water concentrations at the bottom of the water column are still a main factor, with levels over 20 ppt until past station 6.  The closer case study examination is helpful in illustrating this as well. The concentration of salt water at the bottom is relatively steady, in this case study example, we used the high value for station 3, effectively showing the steady delineation in salt water concentration. The top water concentration fluctuates substantially from station 2.5, 3, and even 3.5, where data values range from 1.1 ppt (station 2.5) to 21.9 (station 3.5). We hypothesize that this is because of the high flow rate around this area flowing from the walking bridge to under the bridge on Red Brook rd.

During the spring semester, we were looking for ways to improve upon our previous monitoring data, and gather enough data to get a more precise look at the salt wedge.As we have discussed, the salinity at station 3 had the highest variability, so we decided to add on stations 2.5 and 3.5 (figure 2). This should also be monitored during following years to come. During astronomically high tides example April 25th, 2017, at station 3 at 0851 there was a high range of mixing within the halocline.  During this time at station 3 the tide was at a standpoint “slack tide”  and very soon after started to recede back into Buttermilk Bay.  

        In regards to our case studies of the levels of salinity at 2.5 and 3.5, on low tide days where salinity is undetectable at station 2.5 it is detectable at station 2. This data suggests that the salt wedge is located in between stations 2 and 2.5. This poses problems for monitoring because it is located along a meandering part of the estuary with little access other than trampling over salt marsh plants.

VII. Conclusion

        The heavier, denser saltier water is found near the bottom while salinity levels at the top of the water column disappear earlier on as the station numbers increase. Also as expected, the halocline is ultimately tidally dependent. Along with the tides, the phase of the moon has a strong influence on the salinity levels along lower Red Brook. The tide is the largest factor contributing to salinity levels in lower Red Brook. The tide also may play a large factor on the flow rate of water underneath the footbridge and the road bridge. This contributes to the amount of mixing experienced at these locations. Around low tide, the halocline can be observed as existing between stations 2 and 3. This semester offered us a new opportunity to study two new stations labeled 2.5 and 3.5 (figure 2). Through our monitoring of these new sites, we observed that the salt wedge exists more precisely between station 2 and 2.5.  On a high tide during a spring tide, salinity levels are to be expected as high as station 7, but usually not past station 8. Observable salinity measurements for the top of the water column  made it as past station 5 on three occasions. The bottom concentration of salt water made it past station 5 on five occasions. Out of all the sampling occasions over 2 semesters, only once did topwater and bottom water  contain observable measurements of salinity at (and past) station 8, this was on the King Tide, November 15, 2016.

VIII. Recommendations for next years Environmental Monitoring class

• Stake out each station with metal rebar for accurate depth measurement and consistent YSI readings (at the same location every time)  at each station.
• Adding two new stations into the study; stations 2.5 and 3.5.
• Brainstorm ideas to gain easy access in order to obtain a reading in between stations 2 and 2.5 . Walking in the stream may be the best form of access.
• Measuring the flow rate of the brook to understand more of the salt wedge that highly fluctuates at station 3. In order to get a better understanding of the salt wedge in lower Red Brook.  
• GPS points at each station to measure the gradient level of Red Brook.
• Our team also recommends that there should be another station after two that is before the bridge and around the bend of lower Red Brook before the bridge.  This will also get a better reading of salinity during spring tides.