Looking for fish habitat on the Magothy with a 4-year-old
Peter Bergstrom is a biologist with the National Oceanic and Atmospheric Administration (NOAA) Chesapeake Bay Office.
On Friday, July 3, I did my usual twice-monthly volunteer
water quality sampling at four
sites on the Magothy River near where I live. I started doing this in 1991 through
a program run by Anne Arundel County to get a better understanding of Bay water
quality, and I’ve kept doing it ever since. The county program was
discontinued, but I’ve continued sampling with the Magothy River Association,
which has other volunteers who also do water monitoring.
This monitoring trip was different from recent ones because
my four-year-old granddaughter came with me. This was only the second time
she'd seen any part of the Chesapeake up close
(she lives in Vermont
and usually visits us at Christmas). Thus, I was thinking about how she
was reacting to it. It’s been a long
time since my own kids helped me with monitoring (my youngest child is 26).
My granddaughter at
Bayberry next to the pier where we sampled, holding some crab legs she found on
the beach. Taken with a cell phone camera.
We started our sampling at the end of the Bayberry pier, on
the south shore on the lower part of the river’s mainstem, where all seemed to
be well. Several people were catching juvenile spot (Leiostomus xanthurus) pretty regularly, and my granddaughter was
fascinated by watching them. The reason they were able to catch these
bottom-dwelling fish at that location was apparent when we measured the
dissolved oxygen (DO): it was over 8 mg/l on both the surface and bottom,
plenty of oxygen for fish. The bottom DO here has not fallen below 5 mg/l
(the EPA and state standard for fish habitat) since I started sampling at
Bayberry in April.
The fish & DO story was different at the three other Magothy sites I
sample, and the news was not good.
At the first two these sites, Ulmstead in the mouth of Forked Creek and in my
own neighborhood (Stewarts Landing) on Old Man Creek, the bottom DO was less
than 1 mg/l at both sites, but that’s fairly common in the summer. There were no weird colors or smells, and people
were fishing or crabbing in shallow water nearby, although not in water as deep
as where I sample.
However,
in upper Cattail Creek in Berrywood, the water was a weird milky green and
there was a musky smell, so I knew before I lowered the meter that the DO would
be bad. The color and the smell are both signs of an algae bloom that
died and is decomposing. The surface DO was only 0.7 mg/l, the second
lowest surface DO reading I've ever made, and the bottom DO was definitely
anoxic with 0.00 mg/l, the lowest DO meter reading I’ve ever seen.
My granddaughter can't quite read numbers yet, but she knows zero when she sees
it. It made me sad to show her how dead the creek was. Amazingly there
were no signs of any dead fish; I think the fish usually avoid the whole upper
creek when it's such a dead zone. I’ve never seen anyone fishing or
crabbing nearby. A week after I sampled
there, Cattail Creek had a
health advisory against swimming posted by the county health department for
high bacteria levels, so that creek has multiple problems.
The water quality in these creeks was not always this dismal. Both Cattail and
Old Man creeks were much healthier in 2004 and 2005, when dark false mussels
covered almost all of the hard surfaces over a variety of depths in both creeks.
By pure luck, when I chose my sampling sites in 1991 I picked two sites that
would have some of the densest mussels 13 years later, so I have been able to
document the water quality improvements that followed their filtration. Water
clarity (measured by Secchi depth) and bottom dissolved oxygen showed dramatic
improvements in both creeks in those years, and underwater bay grass (SAV)
acreage in the Magothy went up in both 2004 and 2005. Volunteer divers and kayakers organized by
Dick Carey of the Magothy River Association estimated the number of mussels and
the volume of the creek. From that research they estimated that, in 2004, the
mussels could filter the water in Cattail Creek every two days, while it took
them 15 days in 2005. (Watch
an eight-minute video about the mussels and the 2004 surveys.) Imagine how
healthy the Bay would be if oysters were filtering its water every two days, or
even every 15 days.
People who remember the mussels from 2004 keep asking me how
we can get them back, along with improved water quality. I don’t have an easy answer. Memories of the mussels do give me hope that
improvement is possible. I just wish the
mussels and the good water quality were still here to show my granddaughter,
instead of zeroes on the DO meter.