Publication Date:
2022-05-26
Description:
Originally issued as Reference No. 50-48, series later renamed WHOI-.
Description:
Between July 25 and August 7, 1950 the Woods Hole
Oceanographic Institution conducted a survey of Great
South Bay. The purpose of this study was to attempt to
determine the cause of the almost complete cessation of
the once prosperous oyster industry. Statistics show
that the seed oyster production of the bay declined
steadily for ten years prior to 1935 and has subsequently
been negligible. The yield of market oysters fell from a
maximum of 350,000 bushels in 1929 to 60,000 in 1944 and
is now non-existent.
Systematic records kept by the oyster companies,
notably Bluepoints and Van der Borgh and Sons, provide
strong evidence that the failure of oysters to fatten and
grow properly is associated with the periodic occurrence
in the bay of luxuriant "blooms" of microscopic plants
which they have named "small forms" because of their
minute size and difficulty of identification. This view
is supported by experiments conducted by V. L. Loosanoff
and J. B. Engle of the U. S. Fish and Wildlife Service who
report that oysters stop feeding in the presence of heavy
concentrations of algae.
The problem which the investigators were asked to
examine was whether evidence could be found that the circulation
of water in Great South Bay has altered in such
a way as to account for the failure of the oyster industry
or whether abnormal chemical conditions arising from
pollution or otherwise might provide an alternate or supplementary
explanation of the difficulty. The frequent changes
in the inlets cutting the beach and particularly the apparent
restriction of Fire Island Inlet and the new opening of
Moriches Inlet in 1931 suggest that changes in the circulation
of water have taken place and have led to various proposals
for modifying or supplementing these openings. On the other
hand, the duck farms along the tributaries of Bellport and
Moriches Bays have increased production substantially during
the past twenty years and it has been suspected that pollution
resulting from these farms may have provided conditions
favorable to the growth of the small form and have thus been responsible for the failure of plantings of market oysters.
An examination of records kept by the Coast and Geodetic
Survey indicate that the tidal circulation of the bay has
been reduced over the years. The change occurred prior to
1930 and thus preceded the decline in oyster production.
The results of a survey of the salinity and tidal movement
made in 1907-08 for the New York City Water Supply Board,
when compared with information obtained last summer,
indicate that the change in conditions has been small
except in the eastern extremity of the bay. There a most
important alteration has taken place. Whereas in 1908
Bellport Bay was relatively fresh, having only 1/3 the
salinity of sea water, it now contains about twice as much
salt as formerly. This change undoubtedly results from
the opening of Moriches Inlet which permits salt water to
flow with the rising tide into Bellport Bay from Moriches
Bay and Inlet.
The opinion is widely held that relatively brackish
water is favorable to the production of seed oysters. It
is believed, consequently, that the opening of Moriches
Inlet may be responsible tor the failure of the seed oyster
industry which was formerly centered in Bellport Bay. However,
in the greater part of Great South Bay, where formerly
market oysters were planted, the change in circulation does
not appear to be sufficient to account for the failure of
oysters to fatten properly.
The results of the chemical studies indicate that the
bay water is unusually rich in the products of decomposing
organic matter. These materials appear to originate in the
tributaries of Moriches Bay and the Carmans River from where
they are carried westward across Great South Bay and provide
nutriment for the growth of the great population of microscopic
plants. These observations point strongly to the
duck farms as the source of abnormal conditions in the bay.
The survey has thus revealed two conditions which in
combination appear to be responsible for the unfavorable
conditions affecting the oyster industry. One is the
pollution of the bay by wastes from the duck farms which
provides nourishment for the great population of microscopic
plants, which appear each summer; the other is the local
change in circulation occasioned by the opening of Moriches
Inlet which has increased the salinity of Bellport Bay. In
considering remedial measures both these conditions should
be taken into account.
Since the state of pollution depends on the balance
between the rate at which pollutants are added and their
removal by the circulation of water, the conditions might
be improved by enlarging the inlets or cutting new openings
designed to increase the flushing of the bay. To be
effective these engineering works would be prohibitively
expensive and their effectiveness and permanence would be
uncertain. In addition, they would not restore the low
salinity of the eastern end of Great South Bay which appears
to favor seed oyster production.
A second alternative is to reduce the pollution at its
source by preventing the wastes from the duck farms from
reaching the water. The manure might become a valuable by-product
of the farms if procedures were developed for using
it for fertilizer. Even it such procedures did not yield
a profit, they might at least pay the costs of preventing
pollution. While this expedient might be expected to improve
the conditions in the bay as a whole and thus might lead to
a restoration of market oyster production, it would not
restore the low salinity of Bellport Bay, on which the seed
oyster production supposedly depended, unless Moriches Inlet
were to be permanently closed. It this were done, the conditions
in Great South Bay might be expected to be restored
to very nearly those obtaining prior to 1930.
A third alternative, which has much to commend it, is
to prevent the exchange of water between Great South Bay
and Moriches Bay. If this were accomplished the wastes from
most of the duck farms would be prevented from reaching
Great south Bay. In addition, the waters of Bellport Bay
might be expected to become much fresher and the conditions
would favor the restoration of seed oyster production in
that area. Inasmuch as it is now proposed to bridge the
narrows at Smith Point to provide a roadway to Great South
Beach, it is suggested that at reasonable additional expense
the opening might be filled completely except for a lock for
the passage of boats along the intercoastal waterway. Such
construction would eliminate, or place under control, the
movement of water between the bays and should lead toward a
restoration of the conditions required for the production
of both market and seed oysters. While this method of
improving the conditions, appears to be the most practical one,
it should be realized that it would require either the maintenance
of Moriches Inlet as an effective opening or the
correction of the pollution of Moriches Bay, since otherwise
the isolation of Moriches Bay from the ocean would lead to
intolerable conditions.
Keywords:
Oceanography
;
Oysters
Repository Name:
Woods Hole Open Access Server
Type:
Technical Report
Format:
application/pdf
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