CTFishTalk.com: Climate Induced Acidification of Marine Soils - IMEP #47 - Connecticut Saltwater Reports ( CT Saltwater Reports ) - A Community Built for Connecticut Fisherman.

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Climate Induced Acidification of Marine Soils—IMEP #47
Impacts Upon the New England Historical Soft Shell Clam (Mya arenaria)
And Hard Shell Clam (Mercenaria mercenaria) Shellfisheries
(IMEP Habitat History Newsletters can be found indexed by date on The Blue Crab.Info™
website: Fishing, eeling and oystering thread) and Connecticut Fish Talk.com Salt Water Reports

Timothy C. Visel
Coordinator, The Sound School Regional Vocational Aquaculture Center
60 South Water Street
New Haven, CT 06519

Aquaculture and Restoration: A Partnership N.A.C.E., M.A.S. and I.C.S.R. - December 12-15, 2012, Groton, CT USA
Preface Marine Soils
This paper was presented for the N.A.C.E. meeting in Groton, Connecticut in 2012. It reviews some of the first NOAA research about the negative impacts of pH upon shellfish; completed in 1972 (see appendix). Since 2012, I have revisited the marine soil alkaline and pH shifts from marine soil bacteria. Marine soil cultivation may not only bring enhanced sets of bivalves but also alter the relationship of bacterial populations in addition.

In a review of Gary Magnants research on Cape Cod (1982) (Osterville-North Bay Soft Shell Clams) (The effects of the Hydraulic Harvesting of Soft Shell Clams – South Eastern Massachusetts University unpublished report 1982 (21 pages) he suggests that hydraulic jet clamming (called the Yarmouth wand) may not only cultivate marine soils, but by injecting alkaline seawater with oxygen, may also alter reducing bacteria; very similar to the concept of aeration at waste water treatment plants. Storms may have not only acted as a natural bay or cove “filter cleanings,” but also rinsed soils of organics, reintroduced oxygen into bay bottoms and by doing so allowed “aerobic” bacteria to overwhelm sulfate reducing bacteria which are now linked to the formation of Sapropel. Mr. Magnants research found that jetted bottoms held more clams which appeared to grow faster; I observed the same features also.
At the same time the Northeast Atlantic Oscillation for decades in a positive phase turned sharply negative in 2010-2011. This is the reason for deep bulge in the eastern storm track that looks like a giant horseshoe across the central US, especially last winter along with its characteristic polar vortex. A negative phase for New England is associated with more powerful storms and colder temperatures. I don’t think anyone looking at the past three winters would say they were anything like the winters of the last decade here in Connecticut.

Some recent questions have come in about the cultivation aspects of previous winter blue crab dredge fisheries (aside from the resource management aspects); did the winter dredge fishery for blue crabs help the bottom by stirring or breaking up Sapropel (putrefied muck) deposits without that much knowledge of this fishery, I would say yes, it did. Any breakup of sulfate reducing bottoms would help reduce the toxic larval impacts if it was natural (mentioned in the body of this paper) or manmade. The larger question is that could years of storms remove Sapropel and reverse habitats changing the dynamics of entire estuarine populations. Several researchers are looking into the remains of paleo shell deposits (middens) left along our shores by Native Americans for evidence of such climate cycles and coastal habitat reversals for species. This has been included as a possible Capstone Project: “Did Native Americans Leave Us A History Lesson For Climate Change?”

I respond to all emails at tim.visel@new-haven.k12.ct.us

Abstract

As New England’s summer temperatures moderated in the late 1870s, a time when New England residents were worried about the possible return of glaciers, storms raked the coast as extreme cold and hot periods created climate instability. Then the powerful storms ceased and temperatures increased. After nearly constant “cultivation” marine soils stabilized as a warming period with few strong storms occurred.
One of the first indicators of changed marine soil conditions was seen in the soft shell clam (Mya arenaria) fishery. A small community in Cape Cod, Chatham, was perhaps the most exposed coast to the Atlantic Ocean’s energy pathway. It fell quiet after a decade of violent storms. As summers warmed in the 1890s, the soft shell clam populations were immense in its recently cultivated, and therefore alkaline, bay and cove marine soils. Clam beds were often “cultivated,” plowed and dressed with loosened soil naturally. Chatham’s soft shell clam fisheries soared, and the area would soon become a leading soft shell clam producer.

As the heat intensified, marine vegetation, especially eelgrass (Zostera marina), grew to immense densities and formed meadows which extended out off the Cape to the depth up to 60 feet. As sea grasses grew in the intensifying heat, flushing rates in near-shore areas decreased, organic matter filled soil spaces, and these sub-tidal marine soils acidified. Although the industry was blamed (over-harvesting was often stated), the fact was it was a climate-induced habitat failure as marine soils acidified and became unsuitable for clam sets. When sets failed the surviving clams were “dug out” by a developed fishery - masking the habitat failure for overfishing.

We have the works of David Belding of Massachusetts and others for this early research regarding marine soil acidification to which I refer often.

Today, a century later, the shellfish industry again is witnessing acidification of marine soils after a similar prolonged period of high heat and low energy (storms). Agricultural past practices sought to reverse soil acidifications with the one tool shellfishermen had – energy. Efforts on Cape Cod in the 1970s and the later 1990s renewed interest in marine soil cultivation.

Climate and energy pathways have huge implications for shellfish aquaculture industries worldwide.
Shellfishermen a century ago knew about soil acidification; they witnessed it. Terrestrial farmers also practiced anti acidification of soils liming their fields to overcome the reduced yields from acidic soils. For nearly a century, the United States Department of Agriculture’s public outreach agency the Cooperative Extension Service had staff (many called County Extension Agents) educate the public about the value of soil pH testing. A common spring activity, its pre-planting message always contained a phrase “make certain you get your soil tested,” and had offices that accepted soil samples from the public. Test results guided liming soils to raise pH levels, but those early farmers of the sea had also learned about the importance of soils and pH. Certain marine soils were better for some organisms; soils high in clay for example, were not that good for hard shell clams. Marine soils with high organic loading or heavy accumulations of leaves (especially oak) often slowed poor soft shell clam growth, recruitment and survival. Marine soils with good water circulation and larger grain sizes promised faster hard shell clam growth and firmer shells. When hydraulic harvesting methods for the hard clam quahog was introduced into Connecticut in 1958 clammers quickly became farmers. The age of controlled marine soil cultivation was upon us.

Key Words: Estuarine shell, pH of marine soils, increased clam sets; marine soil cultivation; marine soil testing and survey equipment.

Introduction –

Many believe that the foundation of agricultural soil science can be placed at the feet of George Washington. Few people are aware that second only to the founding of our country, was President Washington’s immense interest in soil science. The placing of ash waste on soils is largely credited to him as carbon replenishment to the demands of the broom plant, a valuable export cash crop at the time. Connecticut as well as other New England states often quickly exhausted thin glacial soils, and Washington’s research on crop rotation, pH controls and soil nourishment are just as valid today. In fact, a large part of Connecticut farmers moved to Pennsylvania in search of better “soils” and was known as Connecticut’s “western lands.” The George Washington of New England marine soils so to speak, is attributed to Richard W. Burton, a former US Public Health Department Shellfish Unit biologist and oceanography teacher at Brockton High School who first demonstrated the cultivation aspect of pumped seawater upon soft-shell clam flats in the early 1970s. Using donated materials, he demonstrated the cultivation and pH modifications of seawater jets upon Scituate tidal flats of the North River (for a detailed history report of the soft shell response to natural energy systems and increase in soft-shell clam sets, see website publication titled “Economic Potential of Utilizing Sub-Tidal Soft Shell Populations in CT.” It is available on the Sound School website, http://www.soundschool.com/directory.html - paper #43 and also “Soft Shell Clam Habitat Creation and Associated Population Expansion follow significant Marine Soil Cultivation Disturbances, http://www.soundschool.com/directory.html - Paper #23.

A 1974 Yankee Magazine article “Aquaculture and the Man with the Blue Thumb” focused upon the hydraulic pump cultivator and reviews Richard Burton’s shellfish cultivation experiments. The article details not only his desire to cultivate marine soils but laments about the lack of applied research in this area. As with natural energy events hydraulic cultivation of marine soils resets a “habitat clock” for soft shell clams. Dr. Burton (similar to Washington’s desire to maximize production with existing acreage and do it in a sustainable way) saw the hydraulic cultivation of marine soils was a way to accomplish man made cultivation and facilitate clam productivity. The 1974 October article of Yankee magazine contains this quote: “As a former government biologist, he saw ‘billions spent in research’ and a vast amount of knowledge accumulated, ‘but it bothered me that at the end of a year, you’d think over what you accomplished- and you learned a lot- but you couldn’t point to one solitary clam or oyster that was there because you helped it get there.”
He was able to obtain soft shell clam sets in areas long unable to set naturally with this seawater cultivation. This is a manmade cultivation activity similar to natural events such as from storms and barrier beach cuts raised marine soil pH (for an in-depth review of soft shell clam responses to energy, see paper # 43 Economic Potential of Utilizing Sub-Tidal Soft Shell Clam Populations In Connecticut – http://www.soundschool.com/directory.html). Shellfisheries of the last century often mentioned this positive soil cultivation aspect – with respect to acidic conditions especially with the soft shell clam, Mya. Dr. David Beldings work on Cape Cod at the turn of the century is a direct link to current estuarine soil studies.

One large factor that Richard Burton had discovered and also James Kellogg a century before him was the negative impact upon organic acids and soil acidity upon shellfish. Marine soil pH today is quietly becoming a large research area and is subject of several studies – both short (habitat quality) and long term (environmental quality) for shellfish and finfish, especially winter flounder.
The cultivation of marine soils as its terrestrial counterpart promises to be just as complex, but important to sustainable (crop and bed rotation) industrial shellfish production practices. Connecticut has thousands of acres of intertidal habitats capable of clam production; however ocean acidification threatens marine soils worldwide and impacts potential future shellfish harvesting. Acidification is seen to impact one of the natural habitat balances of calcium also containing buffering compounds, primarily in coral reefs and in more temperate climates, estuarine shell. Estuarine shell is emerging as the most critical habitat type for a wide assembly of marine organisms. For a discussion of estuarine shell habitats, contact Susan Weber, Adult Education and Outreach Coordinator at the Sound School for a paper titled, “The Importance of Recycling Estuarine Molluscan Shell” and discussion presented at the HRI meeting in November 2011.

To cultivate marine soils, the shellfish industry would need something equivalent to the terrestrial plow. In fact, some of the first soil cultivation experiments were commenced in the 1880s in Bridgeport, Connecticut along the Pleasure Beach soft shell clam flats using horse drawn “land” plows (US Fish Commission Report – George Goode, Editor, 1887, page 590). It wasn’t until the “dry” dredge or drag was made “wet” with the introduction of the hydraulic (water) pressurized manifolds did a comparative marine plow came into existence. The introduction of hydraulic harvesting would as its terrestrial counterpart requires that from time to time the soil is allowed “to rest” and biologically and chemically recover. Continuing to plow over immature seed crops on land can be quickly observed and halted- the same is true for marine soils and jetting immature clam beds over and over greatly eventually diminishes productivity. This was one of the hydraulic harvesting concerns expressed by Frank Dolan of Guilford CT – See publication #26, The Hydraulic Cultivation of Marine Soil to Enhance Clam Production. http://www.soundschool.com/directory.html It is now the most popular of our adult education and outreach papers. Mr. Dolan shared his experiences with marine soil cultivation beginning in 1975.
In one 1985 experiment, a metal mesh liner was installed on a hydraulic hard shell clam dredge resulting in dredge hauls of almost pure seed clams. Underwater this over cultivation often goes unnoticed but nevertheless occurs. Obtaining the best marine soil information is not a desk top or computer search activity. It is field work and sampling activity. Clam beds need to be checked for sets and shell erosion if the pH drops below optimum levels. Oyster growers of the last century frequently noticed enhanced sets of hard shell clams in or near areas of oyster shell.

To obtain good marine soil classification and condition information samples need to be taken, composition determined, pH measured and observations recorded. Marine soil characteristics may include visual and chemical (odor) indications, when pinched between fingers. I have put together a quick reference chart.*
[size=9pt][size=9pt]
Culture/growth pH Marine Soil Samples Textures and Recurring Characteristics Odor
I Positive 7.8 to 8.3 large grains/sandy rough/gritty “honey sugar sand” salt/seaweed
light brown/tan

II Slightly positive 7.5 to 7.8 small grains- same sand smooth grit, darker brown to black smoke

III Neutral 6.5 to 7.5 small gritty, smooth/slippery (organic light black slight vinegar

IV Negative 5.5 to 6.5 smooth muck/loose, some grit (silt) black organic slight sulfide

V Strongly Negative less 5.5 smooth mayonnaise* greasy (stains hands) organic compos (Rotten egg
black strong sulfide odor smell) [/size][/size]

* These soils represent active shellfisheries that work the bottom with hand or towed implements. Set occurs as a result of periodic storms that rinse organic acids from the top layer and can catch a set. Soil type II and III can be made productive with cultivation and the addition of estuarine shell. Poor tidal flushing can create unfavorable additions with the accumulations of partially decayed leaves – Remember Oak leaves have a pH 3.7, pine needles pH 3..5, maple leaves pH 3..2. Tannic acid in oak is also problematic as it seals respiratory pathways and drives sulfide levels up in buried soils. These soils then become “composting” and generally unsuitable for clam sets.

* Black Mayonnaise is an accumulating aquatic compost with much marine and terrestrial plant material properly termed “Sapropel.” Bacterial decomposition processes in warm oxygen depleted waters can produce a very low pH material sampling often stains shells, sand and skin and leaves a rotten egg odor (smell). Gloves are a good idea for long periods of sampling work with this material. A similar blown debris partially composted is called oatmeal by New York Great South Bay fishermen. In the natural environment it is light brown until disturbed and when studied gas bubbles emerge periodically in clusters.

The classification of marine soils I to V refer to generally observed conditions, obtained by way of shellfish surveys in four states, Cape Cod MA, Rhode Island, Long Island, NY and Connecticut. Certain areas tend to contain certain types of soils very dependent upon location (energy zone) and runoff of land organic matter.

Soil type #1 – open waters, shorelines and bays
Larger grain sizes – sandy “sharp”” rough and gritty – RI called honey sand; Cape Cod storm sand; CT, new sand. Found in waves, sand bars and cuts, beach fronts and bars.

Clams – soft shell – excellent sets but could be washed out by storms shallow water hard shell clam sets here are frequently consumed by conch and crab predators; hard shell clams can grow fast here, shell surface has pronounced sharp ridges or lines soft shell clams here very smooth and white shells. Low amounts of organic matter present. Fast growth sometimes produces “paper shells” or very thin shells. This soil needs the addition of shell to strengthen shells if too thin.

Soil Type #II – Interior Bays – Semi Protected Areas
Fast growth at first often produces thin shells; coves, harbors, mouths of rivers, bays and offshore areas frequent storm cultivation but not excessive – sets every 5 to 10 years- less energy provides a smaller grain size; grit and more rounded polished sandy /muddy soils. Organic matter is low if present; and broken shell cover exists, clams that set here have a good chance to survive; shells stained black or gray, soft shells can be “dents” shells that are “lumpy” by small pebbles or shells Quahog Clams (hard shell clams) have good growth on shell covered bottom, have strongly tapered shells, called “sharps” ridgelines; still apparent, lips clear white showing fast growth and clams have strong shells in this soil type. This is the predominant soil type found in Bull rake Hard Shell Clam Fishery in Rhode Island. If cultivation or storm activity ceases these soils may “fail” over time as they become more acidic.

Soil Type III Locations the same as soil type II- Sandy/mud – includes river mouths

This soil type characteristically has various year classes – sizes of shellfish from adults to seed; large soft shell clams live deeper exhibiting slower growth. Large Quahogs appear “blunted” shell ridges gone by a generally smooth shell surface; younger clams show good growth but recent sets “patchy” not as dense. Clam shells can be thick showing age, hard shell clams, especially. This shows that over time this soil was positive for pH 7.8 to 8.3 or higher but has accumulated fines, or had increasing percentage (LOI) of organic matter. These are the beds that suddenly “appear” in historical US Fish Commission records after cold and strong storms. This area is where you can find good sets that mature over time after very strong storms or hurricanes. (Compares with forestry growth after a forest fire.) The Great Nantucket Quahog Clam Bed of 1908 is an example perhaps set after the Portland Gale of 1898.

Soil type IV Mucky “Sticky” Soils, Interior Rivers, Lagoons, Shallow Salt Ponds some clay -more protected coves, upper reaches of tidal areas/tidal river banks silty/mud fines. Shellfish scarce but evidence of sets years past; adults mostly, shells soft and pitted and weak (soft shells) Quahogs very large and old individuals – blunts. Shells extremely thick and soft showing increased shell erosion, no recent sets. Low pH is lethal to setting veligers (Belding 1910). Quahogs can be 50 years old or more (this soil type can be found in deeper Long Island Sound waters). This is the soil type that “reverses” only after extremely strong hurricanes and cold temperatures. See paper titled: The Rhode Island Great Sets available from Sue Weber and on the website: http://www.soundschool.com/directory.html

Soil type V Same location as IV, areas with restricted flows – sealed salt ponds mucky/silt; jelly like or mayonnaise consistency (Sapropel). Usually no living shellfish can be found but historic references to very old clam populations maps frequently exist. Strong sulfide odors commonly called “dead” or “sour” bottoms by baymen. The composting organic material (Sapropel) can be several feet deep and occasionally beneath accumulations, harder, firmer and buried sandy bottoms are located which upon occasion yield clams dead but shells still paired – they may crumble with handling and can be brittle signifying burial for long periods in acidic soils. A test section of pipe is used to estimate depths to firmer bottoms below. The smell of sulfides can at times be nauseating. Hurricanes/navigational dredging are the only way these areas can support shellfish again.

Marine soils can change tremendously over time subject to man-made and natural cultivation events such as storms. Therefore it is important to realize that marine soils can succeed or transition from culture/growth positives to negatives, very quickly that is natural similar to terrestrial lawn care the reapplication of work (cultivation) can sustain culture/soil characteristics. The addition of shell, crushed, whole or fragments can raise neutral and slightly negative soils pH to those characteristics for positive growth and survival parameters. Most worked clam beds have some shell material and shell hash present. Buried shells can be dug up and facilitate clam sets. Many fishermen find the densest concentrations of hard shell clams in old relic planted oyster beds. Cultivation and the addition of shell are two impacts long associated with hard clam / oyster harvesting/culture industrial practices (Pleasant Bay Cape Cod, 1960s).
In the natural environment marine soils tend over time to become more acidic especially in times of great warmth and low energy cycles and all historical records of clam fisheries agree. Often after strong storm (hurricane) marine soils are agitated, mixed and organic acids rinsed with more alkaline seawater. Some of the “best” clam sets occur after these cultivation events, but once energy is removed, marine soils slowly change and over time, the clam beds “die out” as these soils “fail” as recorded by shell fishermen. The clams however didn’t die; the habitat capacity of the soil, failed as it became more unfavorable.* Some shellfish surveys of Niantic Bay in the early 1980s found buried hard shell clam beds under several feet of black mayonnaise sulfide rich accumulations. Although George Washington had much influence over terrestrial soil science, for marine soils, three people are associated with early research/studies in this area and the works of these three researchers should be consulted:

James Kellogg, US Fish Commission – soft shell clams - soil conditions linked to energy
(1888-1912)

David Belding, State of Massachusetts - both soft and hard shell clams – soil conditions linked to flow and pH (1910-1930)

A.D. Meade, Brown University – soft shell clams linked to energy “digging” and pH
(1904-1912)

Mapping marine soils can assist restoration and production management policies. But soil mapping in the marine area is just in its infancy, as compared to terrestrial / agriculture soil mapping.

* Seed clams planted in low pH bottoms can actually become smaller and shells thinner for an account of an early (1983) culture clam seed project in Niantic Bay, CT. See paper # 28 Connecticut Shellfish Restoration Projects linked to Estuarine Health –Paper presented 9th International Shellfish Restoration Conference Nov 18, 2006- Charleston, South Carolina on website

http://www.soundschool.com/directory.html

Background – Harvest Energy As A Cultivation Process

The introduction of small scale hydraulic soft shell clam harvesting first occurred in Martha’s Vineyard in 1951. This period saw winters become progressively colder and severe winters killed many tidal soft shell clam flats at this time. Steamer clams had become a popular seafood item so people starting looking for market clams. They were found in the deeper areas protected from winter freezes in deeper sections of bays and salt ponds. The use of hydraulics in sub tidal salt ponds soon increased (3 to 5 feet depths) as viable populations soft shell clam continued sub tidally and included a hand held wand (commonly referred to as being invented in Yarmouth, Mass, on Cape Cod) and the hydraulic rake. A hand held manifold or a roller version was introduced several years later. The jetting action was used to harvest sub tidal Mya soft shell clams steamers, but in its use soon became aquacultural as dead Mya beds containing nearly old individuals or still paired dead shells were frequently jetted (see an article that appeared in Cape Cod Times on June 19, 1977). Fishermen were beginning to notice new sets in cultivated soils, growth rates (ages) and differences in shell quality in soils were frequently observed. The resulting black sand called acid bottoms and often containing hydrogen sulfide (the rotten egg smell) from excess organics soils were cultivated and the acidic conditions were reversed. Again after the bottom soil had stabilized increased soft shell clam sets were nearly always found after such hydraulic cultivation. Mimicking sets after storm conditions Cape Cod soft shell fishermen documented higher sets and faster growth after cultivating. See report #23 Soft Shell Clam Habitat Creation and Associated Populations Report of the Bourne Shell Fishermen’s Association and the EPA Long Island Sound study paper concerning regional soft shell clam sets after the Portland Gale in 1898.)

Although cultivating the soil on land had long been an established agricultural practice, the early hydraulic dredges not only reduced harvest breakage from nearly 50% with the New Bedford rocking chair Quahog clam dredge to less than 5% with the water manifolds that fluidized the bottom rather than tearing into it. The invention of the hydraulic manifold for hard shell clammers (1957) would quickly prove to be more than a better, cheaper, less ecologically harmful harvest method. It could also quickly reverse marine soil acidification. The manifold delivers pressured water jets into the marine soil, rinsing it of organic acids. The harvesting process happens when water with a pH of 8.0 to 8.4 is injected into marine soils the equivalent of a lime wash. Clams are more easily gathered when dislodged and long buried shell fragments brought to the surface. The harvesting activity also became both a cultivating and pH modification process. Shell fishermen had noticed this impact after severe coastal storms when waves and currents would naturally wash marine soils of acids, increasing grain size, porosity and water circulation containing new replenished oxygen for depleted soils. Following such events, after soil stabilization huge sets of clams often followed or combined with the presence of estuarine shell was also a good indicator of setting potential. For more information about this impact, see The Great Sets of Rhode Island, a paper for the EPA-DEP Habitat Restoration Committee, March 2010. http://www.soundschool.com/directory.html

The hydraulic dredge also greatly reduced the horsepower required; instead water pressure would dislodge the clams, and soil loosening it before the dredge basket collected clams. This minimized recharged energy into the bottom but also reduced harvest breakage to almost nothing, often zero. *[The Rocking Chair Dredge reflects the motion of the dredge largely controlled by engine RPMs, a quick propeller thrust would cause the dredge to gauge the bottom into a series of bites as the dredge was towed “rocked” with high power. The pressure and forces into the bottom would break many clams. Rock and boulder hits were particularly damaging to vessels and gear. [Some dredge boats employed a weak link apparatus to release the tow cable before severe damage could happen or rip the tow cables apart.]

The rocking chair dredge was an expensive way to capture clams and the introduction of hydraulics soon replaced the “dry” clam dredges of the 1940s. During World War II, the price of seafood and fuel allowances made this clam fishery possible, but the advantages of the “wet” or hydraulic dredge was hard to ignore. Many of the broken hard shell clams were used for bait or just shoveled overboard with broken clam shells. However, in areas of dredge activity such as in New Bedford, Massachusetts the replacing of shell or distributing broken shell pieces – “shell hash” or “shell litter” soon elicited another impact – better clam sets. This had been noticed decades before in the oyster industry in connection to seed oyster plantings in Rhode Island and Great South Bay in New York. Clam fishermen noticed increased productivity in oyster areas than those areas left unharvested or gone “sour”. Sour bottoms was a frequent industry term for those bottoms that smelled badly, denoting increased sulfides, and with warm temperatures they frequently went anaerobic and acid containing. These conditions were commonly associated with bottoms rich in organic matter, (“Sapropelic”) layers of decaying leaves and soft muck filled. Hydraulic harvesting gear similar to plows allowed the cultivation of marine soils to begin. Clammers in particular had witnessed this habitat transition before and in every clam fishery claims in historical reports of the benefits of cultivating the soil or working the bottom are told. Many accounts continue today detailing this cultivation aspect from both fishermen and resource regulators and can be found in historical records and reports. The habitat transition from soils unsuitable to those suitable for clam sets often had a direct pH and soil cultivation link. Largely apparent after severe storms when the wave and current actions redistributed soils as sand bars moved, new inlets cut or widened in response to storm energy. The Great South Bay (New York) hard clam fishery for example, has connections to inlet (tidal exchange) width, generally the wider the inlet, the greater the hard shell clam productivity, as the inlet was reduced or “healed” over time, hard shell clam productivity quickly declined.

Chatham, Mass., has a similar habitat history with barrier beach cuts in the Monomoy System and Pleasant Bay. After severe storms and new inlets or cuts, soft shell clams (steamer) clams responded to newly “washed” soils with increased sets, sometimes with immense densities. In a small way shell fishermen were watching the dynamics involved in natures’ habitat wars, the battle line of marine soil pH and the energy that largely modified it. Acidification of the environment was not a new activity for terrestrial agriculture but an opened door for shellfish aquaculture and greater understanding of the importance of marine soil pH to the clam fisheries.

Within a decade of the introduction of the hydraulic clam dredge Connecticut shell fishermen would realize the benefits of bottom soil cultivation followed by shelling, almost the identical culture practices we take for granted for agriculture (liming / shelling). In a small way, fishermen were now capable of reversing soil acidification just as farmers with soil tests from the Land Grant Universities. The association of shell in the marine environment would take on new ecosystem roles, structure (relief) benefits that an entire range of organisms would also depend, historically winter flounder and small lobster in periods of cold, and others like conch and blue crabs in periods of heat; these relationships we are just beginning to understand, including the temporary reversal of estuarine pH, the impacts upon growth and survival of mollusks and associated fish species.

These features are not new to the user groups (the same can be said of plows to farmers), but introduces a wide range of environmental services in coastal salt ponds and sounds. The presence of estuarine bivalve shell could not only emerge as perhaps the most significant sub tidal habitat type, but as the primary buffering agent for increased marine soil acidification throughout the world. Estuarine shell also promises to be an important area of habitat research as we begin to understand the challenges of acidification upon our environment and the impact of global warming.

For more information about the cultivation of marine soils as it relates to shellfish populations, see the “The Hydraulic Cultivation of Marine Soil to Enhance Clam Production. ” paper # 26 in the Sound School web page directory: http://www.soundschool.com/directory.html Written between 1988-1990, it has now become the most popular of the Sound School adult and outreach publications. The report is actually a combination of 3 individual papers/slide presentations from 1985-1990. It largely details the accounts of Mr. Frank Dolan a hydraulic clammer from Guilford, CT in the 1980s, the account also describes the introduction of the hydraulic clam dredge into Connecticut by one of its first practitioners Mr. Frank Dolan of Guilford, Connecticut; Mr. Dolan reviews its use to enhance clam sets including his dissertations about marine soil pH and the hard clam shell fishery. For more information about the potential negative impacts upon marine soil acidification see the current research being conducted by Mark Green of St. Joseph’s College of Maine in Standish. Dr. Green’s research is focused primarily upon the soft shell clam but is easily attributed to hard shell clam studies as well.

For more information about the early reports of hydraulic cultivation on the soil chemistry of marine sediments for soft shell clams, paper #23, Soft Shell Clam Habitat Creation and Associated Populations - School web page directory: http://www.soundschool.com/directory.html
The Bourne Shellfishermen Association soft (Massachusetts) – shell clam experiments and trials are now reviewed. It is available as a reprint of the 1981-82 report from the Sound School Adult Education and Outreach program. It was written by the shell fishermen of the Barnstable - Sandwich -Bourne area in response to questions upon the ecological impact of hydraulic soft-shell clam harvesting (1979). Public concerns had been raised that hydraulic harvesting was damaging to the environment and the source of bacteria that had closed shellfish areas. Shell fishermen who had used the equipment for years had a far different view: They viewed the equipment as a help as a method for reversing oxygen depletion and now low pH occurring in shallow poorly flushed areas. In one experiment/trial overseen by Burke Limeburner then chief of the Bourne Natural Resources Dept., fishermen invited the public to view a demonstration in Buttermilk Bay. I was also invited as then a CRD County Agent community resource development employee of the University of Massachusetts, Cape Cod Extension Service. The demonstration was organized by the Bourne Sandwich Shell Fishermen’s Association.

One test was in open or certified area and one in an area that had been closed to shell fishing for quite some time. The open area test was a typical hydraulic operation, a few test plunges with a plumbers helper attached to a fine mesh net yielded a dozen or so mature soft shell clams, dense enough to warrant starting the 3 hp. gasoline pump, in this case, fixed to a center seat of a Dyer Dow ™ dingy. Most hydraulic clammers had a small skiff or dingy, and a wet suit (to protect against jellyfish stings) a small metal rake yellow snow stakes to mark the area. The harvesting device base was a reducer coupling that took the 2 inch pump delivery to 1.5” diameter, the same size that oil delivery companies used. In fact, most pumps had the used 1.5” flexible oil delivery hose that was no longer in service. This was a strong yet flexible hose with a female coupling already installed; it was connected to the male 1.5” coupling from the pump delivery and was about 12 feet in length. Some clammers had cut this down to 8 feet in shallow areas. The device was finished with a six foot length of 1 inch diameter cooper water service pipe. It was attached to the end of the orange hose using 2 stainless steel pipe hose clamps. The end of the copper pipe was flanged with a hammer to produce a flattened fan like powerful spray. To many of the public bystanders, it resembled a car wash spray. It took about 5 minutes to assemble. To summarize all components: A 3 hp gas powered 2 inch pump about 180-200 gallons per minute capacity. Sometimes referred to as a trash pump, its 180-200 gallons per minutes flow is a good choice for a 2 inch pump. The intake consists of two 22 inch long straight sections, a 2 inch PVC pipe standard drain vent pipe and a shower strainer attachment one straight piece extends the pump intake over the rail of the dinghy, an elbow (again 2 inches) connects the second 2” section 90 degrees down into the sea water for the suction, which had again a 2 inch domestic shower strainer attached to keep any floatables from being drawn into the pump. All the components except the section of used oil delivery hose were available at local hardware stores. The threaded sections made for quick assembly and at most it took three to five minutes to put all the pipe sections together. The pipe discharge had a 2 inch elbow to the 1.5 reducer coupling to the oil delivery hose. Aside from the pump, the investment in harvest gear was a modest one.

Materials Summary:
One 3 hp 2 inch gas powered pump. p.s. This pump was also used to prepare hard shell flats in Wellfleet for planting hard clam seed cleaned predator protection nets and also washed oyster shell from a barge. It also is a good pump out –etc general purpose pump. I have also used them to pump out boats and spray wash clean fish trap nets in the 1980s.

2 Inch PVC household pipe fittings – 2 elbows, 1 reducer, four 2 inch couplings, a PVC standard shower drain and about 44 inches of 2”PVC pipe.

One section of oil delivery hose female coupling – Note shell fishermen would approach oil delivery firms and ask them for old hoses on the Cape hoses had to be replaced every two years, so they had some to give – remember the female coupling was included.

Four yellow snow drift markers – They used the tall fiberglass rods to mark driveways for crews. The “square” would mark the jetted area. Although modest in design, they are critical. You can lose orientation very quickly and be off the jetted area in just a few seconds without a good reference point.
One section/inch copper water service pipe – Six feet long – tapered end – hardware stores or home centers.

One plumber’s helper plunger on a small mesh net – hardware store or home center
One metal clam rake to collect the soft shell clams – Marine supply or bait and tackle stores.
Equipment notes - Cautions about the fuel. These are gasoline powered pumps so all protocols on this fuel must be followed. Saltwater is hard on pumps, so plastic housings were preferred but even then pumps lasted 3 to 4 years with fresh water flushes and had hard use. Pumping sand was damaging as was seaweed/vegetation. Vegetation was avoided because of pump damage.

Electrical – Each motor had a typical metal ground shut off to the spark plug; each clammer had either an insulated stick or rubber mallet to use this shut off. Wet hands in salt water (no ground) on the metal shut off could result in a shock. Everyone used a rubber mullet with a wood handle to stop the pumps. (I learned the “hard” way.)

Pump Priming – These pumps are not designed to be started “dry”; each pump housing had a thumb screw primer plug on top that had to be unscrewed and primed with seawater before starting. This allowed the pump to create a seal or suction, lubricating these surfaces. Dry starting can damage or ruin a pump also if the suction brakes shut down re-prime as necessary. (See vegetation caution above.)
The best thing to do is to read carefully the pump operations/protocols before attempting to start the engine.

Many clammers work the pump itself to move across salt ponds, certainly not the fastest mode of transit; these pump jets could move (jet themselves) quickly and were in fact quite moveable surprisingly so. I used such pumps to propel small boats for short distances many times on Niantic Bay in Connecticut, and also on Great Pond on Block Island – Rhode Island.

The Buttermilk Bay Demonstration – July 1982 Bourne, Massachusetts

Members of the public were invited to the two part demonstration under the auspices of the Town of Bourne Natural Resource Dept. The first site was an area that was jetted (cultivated) last September (81). It was an area in good tidal circulation and with a brown/honey colored sandy soil. A small 8x8 foot square had been marked out. A few test plunges with the plumber’s helper yielded a few nearly white one inch clams. The bottom was weed free with a surface consisting of soft clam shells some whole but many shell fragments also. Mud snails were present as a few blades of sea lettuce (Ulva species) on the largest of shell fragments. Silversides and Fundulus (killifish) were at the edges in the shallow areas, clearly visible. The sand was golden honey in color and some slipper and jingle shells could be seen sometimes below. The bottom was firm, yet not soft. When the hydraulic cultivation commenced it did for about 3 minutes as the single jet was moved back and forth as to cover the square. The pump was turned off and a few minutes later the water cleared. The most noticeable change was the bottom the jetted area was soft – just as a garden is rototilled each spring, what the surface contained was thousands of small about 1 inch soft shell clams, killifish and silversides now were abundant, small worms were dislodged and the fish no doubt were feeding on them. A rake yielded dozens of nearly white perfectly shaped soft shells, but most within five minutes had started to rebury. About 12 inches of bottom had been turned and careful operation was necessary as not to create large depressions. At ten minutes the clams had disappeared but the jetting had attracted green crabs which quickly attacked any clams that had not reburied. (It was difficult not to step on clams which gave a slight crunch. A Sound School student once described this on a location at New Haven tidal flats as walking on corn flakes which is a great analogy). Those clams were also being attached by many killifish and if in large numbers resembled a piranha attack completely cleaning the shell of exposed meats. Comparing the areas adjacent many more fish were now in or adjacent to the jetted area. Rather than avoid the cultivated area just the opposite was occurring fish were being drawn to it, in large numbers. This area had been open to shell fishermen but was now closed until 50% of seed had reached legal size. The fishermen described the bottom as healthy and not sour (acidic). It compared to the soft-shell clamming I had seen in Dennis, Mass in 1981 and Wickford Harbor in 1979 -1980, Rhode Island. Very few people however came to the jetted area but samples of organisms and clams were brought to the shore in buckets for viewing. All were amazed at the numbers of juvenile clams from a single rake pull that came up, which yielded dozens of them.

The second part of the test was further up into the bay into an area had been closed to shell fishing from high bacteria counts. Few people ventured out as this warm area with a mucky bottom last year had been the source of clammers itch, called swimmers itch in Connecticut, and shallow warm organic bottoms have been known to carry a northern blood fluke—worm parasite that is carried from the mud snail and burrows into the feet of shore birds or human skin for that matter. Clammers itch is enhanced for some reason by warm temperatures. Eventually the blood fluke will perish in human skin but creates for three weeks a pustule that itches incredibly (another good reason for the wet suits) and can make any clamming experience less than positive, so many again watched from shore. This was a difficult way to educate the demonstration attendees as you really need to see the difference in bottom soil conditions. However the area had a crust like covering of loose mulch/muck, that some fishermen described as oatmeal, with patches of white underneath the surface sand was stained black and once jetting started – similar 8X8 area the smell of hydrogen sulfide – rotten eggs -was distinctive. Here the jetting attracted only a few fish and provided no living clams just dead paired ones (shells).

Many shells however did come to the surface but mostly older larger shells nearly all stained black. The shells were brittle when handled and samples had the distinctive sulfide smell. The presence of sulfide was a strong indicator that the soil was now acidic and in the process of dissolving the shell, aragonite. This was described as an unhealthy bottom- it was obvious that the area had not been cultivated for quite some time. No living clams were found and due to presence or organic matter took many minutes for the water to clear. Raked samples of empty shells and a bottom sample in a pail were brought to the shore for people to see. Handling the material tended to turn hands black with a strong odor, so people tended to resist handling it. But the comparison was a good one; few people had the opportunity to see a well oxygenated alkaline soil and oxygen depleted acidic soil within three hours. The difficulty was from a few hundred feet it looked to one observer that fishermen were using something that resembled a car wash sprayer, but at the time we did not have the camera equipment or video technology to photograph bottom conditions. It is interesting to note that the shell fishermen had organized, sponsored the demonstrations and printed research findings independently. Hydraulic shellfish harvesting had been openly criticized as to potential harmful impacts upon submerged vegetation, the destruction of eelgrass beds as one concern that was most frequently mentioned. To the shell fishermen who had daily experienced the harvest of clams, to them soil cultivation and the presence of organic acids described by David Belding 80 years before had become a crisis in the closed shellfish areas. Loss of the open areas and lack of cultivation they feared would only accelerate the process. Eelgrass in many areas had become thick so as to interfere with tidal circulation. To shell fishermen, the increase in eelgrass density and prevalence was a concern and symptom of nutrient enhancement. In the 1960s, rapid growth of eelgrass had suffocated acres of hard-shell clams quickly transitioning marine soils in Pleasant Bay, Orleans; they feared this happening to soft shell clam flats as well.

Summary -
It’s been nearly 30 years since these hydraulic demonstrations and the conditions witnessed by these shallow water shellfisheries has now become widespread. The concern over global warming and nutrient enhanced waters has caused anoxic conditions in many small bays and coves. Oxygen depletion has become a large concern and the increased formation of acidic soils is damaging to many shellfisheries. Only large and powerful natural energy events (hurricanes) can reverse or suspend this habitat succession, turning acidic soils into more alkaline ones. It is suspected that the huge increase in winter flounder fin rot disease in Connecticut in the 1980s is now linked to those acidic and sulfide rich bottoms often containing eelgrass Zostera marina.

We need to learn more about how estuarine soils respond to high organics and the loss of shell. One of the ways to study this impact is to duplicate some of the experiments conducted by the Bourne Sandwich Shellfishermen's Association not for increased shellfish sets the original purpose but to measure the pH changes before and after cultivation and clam sets followed by shelling. Another area to review is the presence of estuarine shell and its pH buffering capacity and lastly the impacts upon estuarine shell on low pH bottoms.

Concerns have been raised recently that during hot relatively storm free periods shell loss from acids breaking clam shell in many areas is faster than biological shell replacement. This is not new to the shellfish industry. Shell loss during The Great Heat a period roughly encompassing 1880-1920 period in Connecticut was suspected to be very high and led to numerous industry conflicts regarding access to shell. A paper titled “The New Haven Lost Natural Oyster Beds” is available from Susan Weber, coordinator of our Adult Education Program. It describes some of the industry’s efforts to secure shell during this time. Global warming and acidification of seawater has profound implications for ecosystem research. Perhaps marine soils will in the near future be studied as intensively as its terrestrial counterparts.

With global food supplies diminishing as the human population now tops 7 billion improved yields of food from marine soils may become more important than that of terrestrial soils.
References/Sources of Information (December 2012).

Reference listing:
Yankee Magazine – Aquaculture and the Man with the Blue Thumb, October 1974
Effects of Environmental and Heredity on growth of the soft clam Mya Arenaria by Harbor S. Spear and John B. Clude fishery bulletin #114

Fish and Wildlife Service Vol. 57
United States Department of Interior Fish and Wildlife Service
For the impacts of low pH waters upon shellfish hatcheries see Marine Fisheries Nov-Dec 1972 Volume 34 #11-12. How Some Pollutants Affect Embryos and Larvae of American Oyster and Hard Shell Clam by Anthony Calabrese Pg 24 to 26.

Appendix
NEW FISHERIES SERIES NO.1
HYDRAULIC HARVESTING OF SOFT-SHELL CLAMS
A Report of the First Six Months - 1981
By GALON L. BARLOW JR., CHRISTINA CAHOON, RICHARD E. CAHOON
DIANE FLYNN
BOURNE – SANDWICH SHELLFISH ASSN., INC

This report was funded by the Commercial Fishermen of Bourne and Sandwich
CONSULTANTS
Burke R. Limeburner, Director of the Department of Natural Resources, Town of Bourne
Michael J. Hickey, State Marine Biologist, Division of Marine Fisheries; H. Arnold Carr, State Marine Biologist, Division of Marine Fisheries, Dr. Arthur Gaines, Jr., Program Director, Sea Grant program, Woods Hole Oceanographic Institute; Gerard Flory, Marine Biologist, Coordinators of the Wareham Aquaculture Program at Wareham High School; Phil Schwind, Former Shellfish Constable, Noted Author, and lecturer on Aquaculture Frank T. Baker, President of the new England Collaborative for Aquaculture, Director of the Aquaculture Innovation Laboratory
PART IV
TECHNIQUES
We began in early February as a four person team, in the attempt to make a living with hydraulic clamming. At first our catch was small, but we continued to work at it, learning as we went along. Day by day our total catch improved, as we developed the different techniques required to use the manifold successfully. By April, it was becoming increasingly evident that this area we were working had an enormous amount of sub-tidal clams.

When the weather improved, more and more fishermen joined us in Little Buttermilk Bay. Although we worked nearly side by side, we were surprised to find that while we were getting our limits on most days, they were doing as poorly as we were when we first started. We can only conclude that this type of fishery requires a certain amount of time to learn the various techniques involved, to be successful. Different substrate, water pressure, speed of pumping, etc. – all play an important part.

PART V
BENEFITS OF THE FISHERY
A. OVERCROWDED BEDS:
Any area favorable to the growth of shellfish, but not fished for any reason whatever, is certainly destined to become overcrowded. The sub-tidal clams in the Little Buttermilk Bay region are no exception. This overcrowding in most cases has slowed the growth rate considerable. In some areas, the clams found were many years older than their size indicated.

A great many not making the two inch legal limit: this stunted growth was also accompanied by many misshapen clams, with round or even s-shaped shells not being unusual. While we found this overabundance to be very profitable, we also noted areas that the mortality rate was extremely high. These areas contained a great many empty shells, and a high incidence of dead or dying clams. When the manifold was rolled across the bottom, gases formed from the decaying matter were observed bubbling to the surface. The substrate was devoid of the usual animal life, such as sea worms and the winkles. After pumping these areas, and removing the harvestable clams, the conditions improved remarkably. The surviving seed was able to return to the newly turned over bottom, while the dead shells and decaying matter remained on the surface. The mortality rate of the remaining seed dropped drastically, and an increased growth rate was noted.

We have also encountered certain spots where they dying process is complete, and only the many clam shells remain beneath the substrate. Though the area has since repopulated with sea worms, and other marine life, as yet, no clams have re-set there. One explanation could possibly be taken from the 1930 Belding Report, which states: “Clams are usually absent from soils containing an abundance of organic material. Organic acids corrode their shells, and interfere with the shell-forming function of the mantle. Such a soil indicates a lack of water circulation within the soil itself, as indicated by the foul odor of the lower layers, the presence of hydrogen sulfide, decaying matter, dead eelgrass, shells and worms. If such a soil could be opened up by deep plowing, or resurfaced with fresh soil to a sufficient depth, it would probably favor the growth of clams.”

Appendix 2
NRCS Natural Resources Conservation Service
Cape Cod Water Resources Restoration Project
Final Watershed Plan – Area Wide Environmental Impact Statement

Shellfish populations are cyclical, and in general follow an eight-to-ten-year cycle of growth and decline in numbers. Shellfishing areas vary in productivity. Good beds are worth thousands of dollars annually, during both the growth and decline cycles; others are barely worth harvesting, and can remain untouched for several years. Over time, unharvested shellfish beds typically become buried in silts and other sediment. This tends to smother the ocean bottom at those sites, and reduce oxygen level in the underlying flats. As oxygen levels fall, shellfish become unable to survive, and those beds that are silted over can become unproductive. Therefore, as long as there is enough economic or recreational incentive to do so, shellfishing can help sustain shellfish populations by disturbing the sea floor, and allowing better exchange of oxygen between sea water and the underlying substrate.

November 2006 Page 4-3

Appendix 3
Marine Fisheries Review
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Marine Fisheries Service

HOW SOME POLLUTANTS AFFECT EMBRYOS & LARVAE OF AMERICAN OYSTER AND HARD-SHELL CLAM
Anthony Calabrese

This article reports the effects of detergents, pH and pesticides on development of embryos and survival and growth of larvae of the American oyster and hard-shell clam. Although LAS detergents are more readily biodegraded than ABS detergents, results indicate that the former are at least as toxic to oyster larvae as ABS compounds. For successful recruitment of clams and oysters, the pH of estuarine waters must not fall below 7.00 for clams or 6.75 for oysters. Neither species could reproduce successfully in waters where the pH remained appreciably above 9.00. Most of the pesticides tested affected embryonic development more than survival or growth of larvae. Some, however, drastically reduced growth of larvae at concentrations that had relatively little effect on embryonic development.

pH

The tidal estuarine waters that form the principal habitat of most commercial mollusks are one of the most complex environments in nature. Yet of the various interacting biological, physical and chemical factors affecting commercial mollusks, pH has received less attention than any other major factor. While the pH of the open ocean usually ranges from 7.5 to 8.5, the pH in tide pools, bays and estuaries may decrease to 7.0 or lower due to dilution, h2S production, and pollution(3). Since clam and oyster larvae must, at times, encounter a wide range of pH in their natural habitat, it is possible that success or failure of recruitment of these mollusks in some areas may be determined by variations in pH. With this in mind, a study was initiated to determine the effect of pH on embryos and larvae of clams and oysters (4).

The experimental setup was described before, but in this case, the pH levels in the beaker cultures were adjusted from 6.0 to 9.5 by the addition of HC1 or NaOH.

There was no significant decreasing the number of clam embryos developing normally within the pH range from 7.0 to 8.75 (Fig.1). The number of both clam and oyster embryos developing normally at pH 9.0 was greatly reduced, and at pH 9.25 to 9.5 there was virtually no development. Clam embryos apparently were not able to tolerate as low a pH as did oyster embryos: at pH 6.75, more than three times as many oyster embryos as clam embryos developed normally.

Both clam and oyster larvae showed about normal survival throughout the pH range from 6.25 to 8.75 (Fig.2). Oyster larvae, however were somewhat more tolerant of low pH levels than clam larvae. At pH 6.0, for example, 21.5% of the oyster larvae survived, but none of the clam larvae. At pH 9.0, some larvae lived for a few days and showed some growth, although eventually more than 50% died; at 9.25 and higher, there was no survival of either species.

The pH range for normal growth of clam larvae was 6.75 to 8.75 (Fig. 2). The pH range for normal growth was, therefore, slightly narrower than that for normal survival. The rate of growth of clam larvae was most rapid at pH 7.5 to 8.0, while oyster larvae grew most rapidly at pH 8.25 to 8.5. Although oyster embryos and larvae survive at lower pH levels than clam embryos and larvae, the optimum pH for growth of oyster larvae is somewhat higher than the optimum for clam larvae. The rate of growth decreased rapidly below 6.75 and above pH 8.75 for both clams and oysters.

It should be emphasized that clam larvae can survive at pH 6.25, which is lower than the pH 7.0 at which clam embryos develop normally; but at pH levels below 7.0 failure of clam embryos to develop normally would be the factor that would limit recruitment of this species (Fig. 4). The percentage of clam embryos developing normally, larval survival, and increase in mean length all decrease precipitously at about pH 9.0; these three factors would limit recruitment of this species.

Oyster larvae, like clam larvae, can survive at lower pH levels than those at which embryos can develop. At pH 6.25, there was a sharp increase in the survival of oyster larvae and only a negligible increase in development of oyster embryos (Fig.5).

In experiments with adult oysters (5) it was concluded that the minimum and maximum pH levels at which they would spawn are 6.0 and 10.0, respectively. The percentage of oysters that spawned at pH 6.0 and 10.0 was considerably lower than the percentage that spawned at the normal pH (7. Cool

of laboratory sea water. In all tests, male oysters spawned more readily than females, and at pH 6.0 it was most difficult to induce females to spawn. Also, eggs and sperm released at pH 6.0 and 10.0 lost their viability within 2 to 4 hours.

It can be concluded that the pH of the tidal estuarine waters that form the principal habitat of the hard shell clam and American oyster must not fall below pH 7.0 for clams or pH 6.75 for oysters, even though the larvae of both species can survive at lower pH levels. Moreover, neither species could reproduce successfully in waters where the pH remained appreciably above 9.0. Laboratory experiments have shown that high concentrations of silt can lower the pH of sea water to 6.5 or below the lower limit for normal embryonic development of clams and oysters. It is apparent, therefore, that heavy siltation, or any pollution that can change the pH of tidal estuarine waters, could cause failure of recruitment of these clams and oysters.

Appendix 4
Sunday Cape Cod Times, June 19, 1977, Page 16
Clams being moved to ensure growth in Edgartown project
By Julia Wells, Staff Writer
EDGARTOWN – It takes about three years for soft-shell clam to grow from the size of a speck of sand to steamer-pot dimensions. The tiny clam is oval with grayish-white rings, just like its grown-up counterpart. But conditions must be right for the clam to grow, and in Wasque Pond on Chappaquiddick there are hundreds of thousands, maybe even millions of tiny soft-shell clams that are not growing.
Edgartown’s acting marine biologist Scott Colby explains that the closed pond does not have high enough salinity for the clams to grow. Soft-shell clams survive best in a salt count between 15 and 30, but they can survive in water as low as 10, according to Colby.

In Wasque Pond, the salinity hovers around 15. There is some leaching which occurs between the pond and the outer ocean, just a few hundred feet across the somewhat static condition of the pond, the clams are not in danger of dying, but they won’t really grow either.
“It’s a perfect nursery—our own hatchery,” Colby says.

As a result a project is actively in progress to move the seed clams to ponds where they will grow. The originator of this project is Nelson Smith, Chairman of the Edgartown Shellfish Committee.

The seed is then hung in the water in burlap bags until transplanting which is done in the afternoon. The clams are planted in their new home by means of a jet pump which softens the bottom enough for good settling in. They are then covered with a fine mesh screen for protection from predators.

So far, the mortality rate has been nearly zero, and about 320,000 seed have been transplanted, according to Smith.

Appendix 5
VILLAGE ADVERTISER, February 3, 1983 Page 23
Hydraulic harvesting help, not hindrance

While reading Cliff Dow’s column January 20th I was surprised to see that he was allowed to diverge so from his boating to take his stabs at the commercial shellfishermen who are proponents of hydraulic harvesting.

Mr. Dow has chosen to misrepresent how hydraulic harvesting of soft-shell clams will destroy the grasses and in turn destroy our bays. If a shellfisherman were to take hydraulic pump and work in the eel grass beds this would indeed be detrimental. This is supported by the study which was done by Gary Magnant not in the Chesapeake Bay, but right here in the “Cow Yard” of the Cotuit Narrows. The grasses form a vital part of the bay system – this has been documented by much research. However, Mr. Dow leads one to the incorrect conclusion that hydraulic harvesting would be done in the grass beds.

If Mr. Dow took a stroll along the edge of the bays and noticed where the clams are located he would recognize the foolishness of his statement. Most clams are found fairly close to the shore in areas where there is little or no eel grass. I would also urge him to study the way the hydraulic harvesting gear works, particularly the type with a manifold. If a fisherman were foolish enough to operate in a grassy area, he would certainly spend more time cleaning and unclogging the nozzles of grass than he would catching clams. The assumption that “we continue to ruin the bottom of our bays by the use of hydraulic dredging of clams which will eventually completely destroy what is left of this one thriving industry and means of augmenting family food supply “ is totally absurd. I for one am tired of being portrayed as the “bad guy” by one who shamelessly flaunts his ignorance of the fisheries. We, as fishermen, share a symbiotic relationship with the waters we fish. Though there are some who care nothing but the satisfying of some great quest for riches at any expense, many more are those who realiz