French Hill Pond: A Decade of Evolution David W. Lind, BA, MSfrenchhillpond.org/PDF/French Hill Pond...
Transcript of French Hill Pond: A Decade of Evolution David W. Lind, BA, MSfrenchhillpond.org/PDF/French Hill Pond...
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French Hill Pond: A Decade of Evolution
David W. Lind, BA, MS
Introduction
This paper discusses changes in the character of French Hill Pond, Bar Harbor, Maine as
observed by the author. The physical chemistry of the pond is discussed followed by the changes
in the flora and fauna in the pond and the adjacent area. The conclusions are not definitive. The
evolution of a microenvironment requires a significant amount of time. A decade is not, in the
opinion of the author, enough time to draw conclusions that will survive the test of time.
However, trends can be identified and help guide future studies that may develop definitive
conclusions.
Most observations were not made during 2015 because the author was recovering from a medical
condition. All photographs and graphics, except the topographic map, are by the author.
Another paper by this author titled: French Hill Pond 2009 Study Report, dated July 2010,
contains detailed information about a study of French Hill Pond most of which will not be
repeated. However, an updated map of French Hill Pond is necessary for the discussion that
follows.
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This map has more detail than the 2010 report map and it shows the character of French Hill
Pond after the removal of a stand pipe at the northern end of the pond and the construction of a
small dam to replace the stand pipe in the natural creek that flows out of French Hill Pond and
into the Fresh Meadow section of Acadia National Park. Fresh Meadow is a part of the Northeast
Creek watershed, considered by many experts to be the most pristine watershed on the east coast
of the United States. The numbers on the pond show the depth of the water in feet at those
locations. The number 10 in the box is the location on the pond where the physical chemistry
analyses were performed. This point is designated the DEEP point and is at 44⁰ 24.163' North
and 68⁰ 18,774' West or 0554714 East and 4916833 North in the Universal Transverse Mercator
(UTM) coordinate system. The State of Maine assigns a number for the Maine Information
Display and Analysis System (MIDAS) to each lake and pond in Maine. The MIDAS number for
French Hill Pond is 4593. The Global Positioning System (GPS) uses the UTM coordinate
system; therefore, the above map uses that system. The coordinate points on the map were
determined by a GPS device with an average accuracy of ±15 feet or less. The following section
of a United States Geological Survey map shows the relationship of French Hill Pond with
respect to Fresh Meadow and the Northeast Creek watershed.
The removal of the stand pipe became necessary when a leak in the conduit caused subsidence
near the road. The road was also flooded after heavy rains making it impassable. With the
assistance from the Town of Bar Harbor, the stand pipe was removed, a small dam constructed,
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some fill added to prevent road flooding and a dry fire hydrant installed. The Bar Harbor Fire
Department has used this dry hydrant to fight nearby fires. The State of Maine has also used the
pond as a source of water for fire-fighting buckets dangling from helicopters. After these
improvements, the character of the pond changed starting in 2012 as will be seen in the data
contained in this report.
Physical Chemistry
The physical chemistry analysis of French Hill Pond includes the measure of the water’s
turbidity (clarity) using a Secchi disk, the pH of the water, water temperature and dissolved
oxygen levels. Beginning in 2016, the phosphate, nitrite and ammonia levels in the pond water
were also measured. These latter measurements were more of an analytic chemistry nature than a
physical chemistry nature but are included in this discussion.
The Secchi disk used is an eight-inch disk connected to a plastic measuring tape graduated in
meters and centimeters. This disk was used with a slant-glass scope and mask. These items were
provided by the Lake Stewards of Maine organization (formerly the Maine Volunteer Lake
Monitoring Program) with the support of the Maine and federal environmental protection
agencies.
The pH of the pond water was determined in three ways. An electronic pH meter and pH strips
were used on the pond. A sample of the pond water was obtained at the DEEP point and later
chemically analyzed. This sample was also analyzed for phosphate, nitrate and ammonia
beginning in 2016 using a water analysis kit specifically designed to analyze pond water. No
phosphate, nitrite or ammonia was found in the pond water indicating that the pond is not being
polluted by septic systems, composted animal or plant waste etc.
The water temperature and dissolved oxygen was determined initially by a Hanna Instruments
dissolved oxygen meter and then by a Yellow Springs Instruments dissolved oxygen meter.
These devices were owned by the author. The dissolved oxygen levels are important because fish
require at least 5 parts per million (ppm) of dissolved oxygen to thrive in a pond.
Secchi Disk Results
The following charts are X-Y scatter charts showing the trends of the Secchi disk readings
during the months of May through October for each year from 2010 through 2019 except 2015.
The first chart shows the Secchi disk readings taken at two-week intervals. No attempt was made
to fit the data to a continuous curve. However, it is apparent that the Secchi disk readings in the
spring are high, decrease during the summer, level off in the late summer into fall and rise again
in the winter,. This pattern may be explained by the facts that plant decay will be slowed in cold
weather, pollen and other excretions from plants and animals increase during late spring and
summer, warmer water accelerates decay and the growth of organisms accelerates in summer.
The winter months slow all processes and allow the suspended particles in the water to settle on
the pond floor. Assuming a smooth transition during the months not included in the study, the
Secchi disk readings follow a broad and shallow sinusoidal pattern suggesting that this pattern
could be statistically analyzed using a Markov process model. Such an analysis is beyond the
scope of this report and, in the opinion of the author, the existing data is insufficient to construct
such a model.
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Secchi disk readings in Maine lakes or ponds range from 0.2 meters to 21.3 meters*. The Secchi
disk readings in French Hill Pond range from 0.72 meters to 1,6 meters. Normally, low Secchi
disk readings are due to algae growth but the major factor reducing the readings in French Hill
Pond appears to be tannin from the surrounding forest. Secchi disk readings of less than 4 meters
indicate the pond is productive*, that is, there is significant flora and fauna growth in the pond.
The next scatter chart shows the average Secchi disk reading for each year except for 2015. The
level of the pond began to drop from 2009 to 2012 because of the leaking standpipe. When this
standpipe was removed and replaced by a dam, the level of the pond became more constant and
the turbidity of the pond began to change.
The change in turbidity seems to be trending to a steadier state in a sinusoidal pattern best seen in
the following scatter chart showing the minimum and maximum Secchi disk readings for each
observed year. Mini/max analysis is a better way of analyzing trends than averaging data because
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
26-Mar 15-May 4-Jul 23-Aug 12-Oct 1-Dec
2010
2011
2012
2013
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2016
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2018
2019
SECCHI DIISK READINGS IN METERS 2010 to 2019
0.95
1
1.05
1.1
1.15
1.2
2008 2010 2012 2014 2016 2018 2020
Average Secchi Reading in Meters by Year
Average Secchi Reading
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it emphasizes extremes. For example, comparisons of the earth’s average, yearly temperature
over a decade may show little or no change but the mini/max analysis of temperature over the
same period may show a clear warming or cooling trend.
pH Readings
The following chart shows the changes in pH of the pond water during the monitoring period.
The pond water tends to be slightly acidic except during the hottest part of summer. These results
are typical of this area. Well water adjacent to the pond, for example, tends to be slightly acidic.
The pH of the water encourages the growth of certain plants and discourages others. The pond
water is becoming less acidic each year.
0
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26-Mar 15-May 4-Jul 23-Aug 12-Oct 1-Dec
2009
2013
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pH
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Surface-water Temperature Readings
The next chart shows the surface-water temperature during the observation period. One might
conclude that the surface-water temperature is on average decreasing with time but the data is
insufficient to draw this conclusion. The temperatures follow a sinusoidal pattern that remains
close to a tight, least-squares curve fit.
The following chart shows the average surface-water temperature for each observation year. The
yearly average surface-water temperature trend is neither increasing nor decreasing.
0
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20
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25-Apr 15-May 4-Jun 24-Jun 14-Jul 3-Aug 23-Aug 12-Sep 2-Oct 22-Oct 11-Nov
Surface-water Temperature oF
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2011
2012
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2018
2019
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2008 2010 2012 2014 2016 2018 2020
Average Surface-water Temperature Degrees Fahrenheit
Average SurfaceTemperature DegreesFahrenheit
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Dissolved Oxygen Readings
Dissolved oxygen analysis is the most difficult process requiring the collector of this data to be
certified yearly by an approved representative of the Environmental Protection Agency. The
meter used requires careful calibration before each use. The dissolved oxygen readings are
coupled with the water temperature at each measurement point to determine the percentage of
oxygen dissolved compared with the maximum amount of dissolved oxygen possible in water at
the measured temperature. The nature of the pond water in French Hill Pond keeps the actual
dissolved oxygen at less than 100%. Only the amount of dissolved oxygen in parts per million is
included in this report because the actual percentage of dissolved oxygen contributes little to the
scope of the report.
The following nine scatter charts show the dissolved oxygen in parts per million during the
observation period. The amount of dissolved oxygen in pond water determines where organisms
will thrive in the pond. Generally, pond regions with dissolved oxygen levels of less than one
part per million are considered devoid of oxygen (anoxic)*. Most organisms cannot thrive under
such conditions. Fish will avoid regions with less than five parts per million of dissolved
oxygen*.
The charts show that there are regions in French Hill Pond that have dissolved oxygen levels that
remain above five parts per million year-round. Therefore, the pond supports fish, tadpoles and
other aquatic animals*. Fishermen should take care to place their bait at less than a meter in the
heat of summer but much deeper at other times of year.
In 2019, a family caught enough catfish in French Hill Pond for dinner that day.
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Dissolved Oxygen at 1 Foot (ppm)
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2016
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0
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Dissolved Oxygen at 2 Feet (ppm)
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Dissolved Oxygen at 3 Feet (ppm)
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0
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Dissolved Oxygen at 4 Feet (ppm)
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Dissolved Oxygen at 5 Feet (ppm)
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Dissolved Oxygen at 6 Feet (ppm)
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Dissolved Oxygen at 7 Feet (ppm)
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Plant Surveys
The following table lists all the plants observed in French Hill Pond or on the immediate shore
during the decade of observations.
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26-Mar 15-May 4-Jul 23-Aug 12-Oct 1-Dec
Dissolved Oxygen at 8 Feet (ppm)
2013
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Dissolved Oxygen at 9 Feet (ppm)
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Plant Common Name (Genus species)
Date First Observed
Algae Blooms (spp.) 2014
Aquatic Moss (spp.) 2011 Blue Flag (Iris versicolor) 2010
Bottlebrush Sedge (Carex hystericina) 2010
Cattails (Typhaceae) 2010
Common Bladderwort (Utricularia macrorhiza) 2010 Common Cattail (Typha latifolia) 2014
Common Mallow (Malva neglecta) 2014
Common Waterweed (Elodea canadensis) 2011
Earth Loosestrife (Lysimachia terrestris) 2014 Erect Bur Reed (Sparganium americanum) 2010
False Baby's Breath (Galium mollugo) 2014
Fern Pondweed (Potamogeton robbinsii) 2011 Filamentous Algae (spp.) 2014
Flatstem Pondweed (Potamogeton zosteriformis) 2010
Floating Bur-reed (Spaganium fluctuans) 2011
Floating-leaf Pondweed (Potamogeton natans) 2011
Fraser's Marsh St. Johnswort (Triadenum fraseri) 2012
Large-Leaf Pondweed (Potamogeton amplifolius) 2010
Little Floating Heart (Nymphoides cordata) 2010
Metaphyton (algae sp.) 2011
Muskgrass (spp.) 2011
Narrow-leaved Cattail (Typha augustifolia) 2014
Northern Snail-seed Pond Weed (Potamogeton spirillus) 2011
Ribbon-leaf Pondweed (Potamogeton epihydrus) 2011
Round-leaved Sundew (Drosera rotundifolia) 2016 Sensitive Fern (Onoclea sensibilis) 2018 Slender Pondweed (Potamogeton pusillus) 2018
Slender Pondweeds (Potamogeton sp.) 2010
Slender Waterweed (Elodea nutallii) 2011
Small Cranberry (Vaccinium oxycoccos) 2014
Soft Rush (Juncus effusus) 2010
Spatterdock (Nuphar lutea spp.variegata) 2010
Sphagnum Moss (spp.) 2012 Stoneworts (Charales order) 2014
Three-petal Bedstraw (Galium trifidum) 2014
Three-way Sedge (Dulichium arundinaceum) 2013
Tufted Loosestrife (Lysimachia thrysiflora) 2014 Variable Pondweed (Potamogeton gramineus) 2011 Vernal Water-starwort (Callitriche palustris) 2010
Waterwort (Elaine minima) 2012
Wild Celery (Vallisneria americana) 2011 Wool Grass (Scirpus cyperinus) 2010
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The primary purpose of the plant surveys was to find invasive species in the pond. Some
suspicious plants were observed and ultimately identified by experts, but no invasive species
were found.
The plants in French Hill Pond were divided into four distinct communities for study purposes
shown on the following map.
Community four, designated the “Sparse” community because of its low density, has decreased
in size since the construction of the dam. Communities one, the “Shore” community, and three,
the “southern” community, have increased in size. Community two, around the island, has
maintained the same size. The densities of community 1 and community 3 have increased
significantly.
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The most common planst in French Hill Pond are members of the Cattail family. There are three
species of cattails in French Hill Pond: Common Cattail, Narrow-leaved Cattail (shown below)
and a hybrid. Virtually all the cattails are in community 1, the Shore community, with a few in
the island community.
The next most common plant is the Bur Reed family. There are two species of Bur Reed in
French Hill Pond: Erect Bur Reed (shown below) and Floating Bur-reed. The Erect Bur Reed is
much more common than the Floating Bur-reed. Bur Reeds are found in the Shore community,
the Island community and are dominant in the Southern community.
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The next table lists all the plants observed in French Hill Pond or on the immediate shore during
2019.
Plants Identified in 2019 Date
Identified
Round-leaved Sundew (Drosera rotundifolia) 05/16
Small Cranberry (Vaccinium oxycoccos) 05/18
Spatterdock (Nuphar lutea spp.variegata) 06/15
Blue Flag (Iris versicolor) 06/28
Soft Rush (Juncus effusus) 06/28
Sphagnum Moss (spp.) 06/28
Erect Bur Reed (Sparganium americanum) 06/28
Large-Leaf Pondweed (Potamogeton amplifolius) 06/28
Three-way Sedge (Dulichium arundinaceum) 06/28
Sensitive Fern (Onoclea sensibilis 06/28
Common Cattail (Typha latifolia) 07/16
Narrow-leaved Cattail (Typha augustifolia) 07/16
Bottlebrush Sedge (Carex hystericina) 07/16
Variable Pondweed (Potamogeton gramineus) 07/30
Slender Pondweed (Potamogeton pusillus) 07/30
Fraser's Marsh St. Johnswort (Triadenum fraseri) 09/30
Note that a great many plants listed in the table above were not observed in 2019. The cattails
and bur reeds have grown so aggressively that many other plants are unable to compete. After
the construction of the dam, algae species have virtually disappeared. Some plants that
disappeared in previous years have reestablished themselves in recent years in areas where
cattails and bur reeds are less numerous, notably the Variable Pondweed and Slender Pondweed.
Certain plants grow among the dominant plants, specifically the Round-leaved Sundew, Small
Cranberry, Blue Flag, Soft Rush, Sphagnum Moss, Three-way Sedge, Sensitive Fern,
Bottlebrush Sedge and Fraser’s Marsh St. Johnswort. These plants are likely to thrive in spite of
the dominant plants.
Plants like Spatterdocks and Large-leaf Pondweed grow in waters too deep for cattails or bur
reeds. However, the pond floor drops off quickly outside the communities. Therefore, it is
unlikely that plant communities will expand significantly in the near future or new communities
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will develop outside the current communities. Another factor that prevents expansion of
communities is the fact that the pond is too turbid for sunlight to penetrate far enough into the
deeper water to allow plant growth in deeper areas of the pond.
The Tarn in Acadia National Park is evolving from a pond to a wetland as plants fill the entire
pond. However, French Hill Pond is not likely to evolve in this way. French Hill Pond is too
deep and the turbidity is too high for plants to grow in deeper areas.
Fauna of French Hill Pond
French Hill Pond is home to a variety of animals. A pair of Canada geese arrives in the spring
each year to nest on the Island in the pond. They rear about half a dozen goslings. When the
goslings are able to fly, the family moves on, no doubt joining other geese further south. The
following photograph shows one of the parents with three goslings.
The next photograph shows the nesting area on the island that they use each year.
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The pond is also frequented by Great Blue Herons as shown in the next photograph. However, no
heron has nested close to the pond.
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Other water loving birds that are frequent visitors on the pond include mallards (shown below).
Black Ducks, Ruddy Ducks and Common Mergansers are also frequent visitors. None of these
ducks were observed nesting near the pond.
Numerous species of birds frequent the shore to catch the many insects the pond produces. The
next photograph shows a Song Sparrow sitting on a cattail flower after catching a fly.
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Snapping turtles (shown below) are in the pond and occasionally found on the shore. Dogs that
swim in French Hill Pond risk being bitten by these creatures.
There are two types of frogs in the pond: Bull Frogs and Northern Green Frogs. The following
photograph shows a Bull Frog on Spatterdock leaves.
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The next photograph shows a Northern Green Frog among some Filamentous Algae before the
dam was built.
The pond also is home to a number of species of fish including the Brown Bullhead Catfish,
Rainbow Trout and minnows. The Rainbow Trout (shown below) were introduced but are vastly
outnumbered by the more hardy catfish.
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The greatest numbers of animals in French Hill Pond observed by the human eye are the insects.
There are far too many to list in this report. The following photograph shows a Half-banded
Toper dragon fly rarely seen in ponds but common on French Hill Pond.
The next photograph shows a Blue Dasher dragon fly. These dragon flies are very numerous
during the summer and many even lite on an observer.
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An insect that can be problematic is the Eastern Yellow Jacket (shown below) that will build
nests in the shore of the pond creating a hazard for people allergic to their sting. Other hazardous
insects common on the shore or water of French Hill Pond are mosquitos and ticks.
There are no indications that the animals in and on the immediate shore of French Hill Pond will
become extinct or be decimated in numbers very soon. They remain as very visible, vibrant,
pond life.
Summary
French Hill Pond has evolved over the last decade. The character of the pond changed more
dramatically since the elimination of a leaking standpipe and the construction of a small dam in
its place. The turbidity of the pond water remains high and seems to be approaching a more
narrow range. The pH of the pond water is becoming more neutral. The surface-water
temperature remains consistent showing neither an increasing nor decreasing trend in average
temperature over the decade.
The dissolved oxygen readings show that the pond water maintains dissolved oxygen readings of
greater than five parts per million down to about one meter year round. The dissolved oxygen
readings at lower levels drop dramatically during the summer but recover by fall to the point that
dissolved oxygen levels rise to above five parts per million down to the bottom of the pond.
These conditions allow aquatic animals like fish and frogs to thrive in the pond*.
No invasive plants were discovered in the pond during the decade. Numerous native plants were
identified and cataloged. Certain plants like cattails and bur reeds have become dominant
crowding out other plants. It is unlikely that plants in French Hill Pond will grow much further
beyond the current plant communities. Therefore, French Hill Pond should be spared an
evolution to a wetland for the foreseeable future.
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There are numerous animals that call French Hill Pond home. Many others are frequent visitors.
One pair of mating geese raise their young on French Hill Pond every spring.
Compared with other similar ponds in Maine, French Hill Pond is fairly typical*. Its importance
lies in the fact that the water from French Hill Pond drains into Fresh Meadow in Acadia
National Park a part of the Northeast Creek watershed. It is important to keep French Hill Pond
as environmentally sound as possible.
The raw data for this report and more detailed information about French Hill Pond can be
accessed through the website: www.frenchhillpond.org.
All photographs were taken on French Hill Pond or on its shore by the author.
Information marked with an asterisk (*) was provided by the Lake Stewards of Maine
organization formerly the Maine Volunteer Lake Monitoring Program.