EC #22-A Bacteria Nitrogen and Submerged Grasses

[BlueChip]

EC #22-A
Bacteria Nitrogen and Submerged Grasses
Environmental Conservation Series The Blue Crab Forum™
View the Nitrogen/Bacteria EC Newsletters on the Environmental
Conservation Thread The Blue Crab Forum™
Tim Visel, The Sound School
Viewpoint of Tim Visel, no other agency or organization
August, 2020 – This is delayed report 

One of the few times people can observe the impact of bacterial populations under grass is when cut sod (grass) is delivered for a new lawn.  Here rolls of carefully cut sod is delivered early in the morning when it is cool (hopefully) if rolls are delivered on pallets this can become more evident as the day proceeds.  As soon as the grass is cut bacterial digestion of plant tissue continues to generate heat - this is the same bacterial action that makes a winter compost pile "stream," even during a light snowfall.  Oxidation is occurring to cellulose and this generates heat – its closely packed condition rolls concentrates the heat.  Plant "organic matter" is being digested surrounded by oxygen in the air by bacteria.  If allowed to continue compost deposits can generate temperatures over 100 f even on a cool day.

It's the action of bacterial consuming organic matter that releases this heat - it's not that much individually, it's that so are so many bacteria under grasses.  It is estimated that only one gram of top soil may contain a billion or more bacteria - this is the "good" bacteria that by the mineralization of elements into ion form which allows plant root tissue to absorb nutrients.  But these bacteria need oxygen to grow in organics and is responsive to both oxygen and heat and why we cool and seal our food in order to slow bacterial growths.

Since bacteria is so important to composting and needs moisture the same bacterial action on cut sod is found in the harvest of hay - grasses that are cut for forage or mulch.  Cut hay should have a low moisture content before being baled - or risk excess bacterial heat becoming so high that the bale can burst into a fire - called spontaneous combustion but this does not fully describe the bacterial "time" it takes to generate that much heat (see "How to Prevent Hay Fires, Don't Add Water" by Steve Orloff and Daniel H. Putnam for Alfalfa and Forage News, April 25, 2013, University of California - Agricultural and Natural Resources) it could take weeks or even months. 

How this happens quickly is cut grass (sod) is now surrounded by oxygen and water - from the moisture held in the sod itself.  Although not baled but rolled the impact is similar - placing layers of bacteria between food (organic matter) with oxygen (air) and water.  This rolled up sod now generates this bacterial "heat."  So how hot can it get?  It can one a large pallet reach 130of in few hours, on a hot sunny day 150oF (most cut sod suppliers provide a fact sheet on keeping rolls apart, cool and often in shade to reduce pallet heat).  Most turf shows stress at 95o and then root damage (See Cornell University Cooperative Extension of Suffolk County fact sheet titled "Heat Stress on Turf Grass - 70oF is the limit for good growth of any consequence").  We know much about terrestrial grasses - we know that soil pH is important and acid soils can support fungus (below 5.5 pH) growth and the best soil pH levels tend to be around 7 - 6.5 to 8 pH, access to oxygen and of course moisture which can be at times limiting (drought) or too much rain resulting in a post flood fungal attack, or energy in this case fire.  These habitat impacts we can observe and have been studied.

That is why often it is puzzling that the study of marine grasses lacks these observations - a habitat clock that like terrestrial grasses shares similar monoculture attributes, bacteria, lack of oxygen, fungal attack or energy in this case waves and storms – hurricanes.  These can all have profound impacts to the marine soil in which eelgrass lives.  The largest difference between grasses that live in terrestrial habitats or even salt marshes is the presence of secondary oxygen containing compounds such as sulfate, nitrate and ferrous iron.  Sulfate a part of the sulfur cycle is an important aspect of marine soil function and the health of eelgrass.  Researchers a century ago talked about the bacteria of marine composts and when sealed from oxygen and the formation of oxygen poor composts, a sapropel.  H.W. Harvey of the Marine Biological Station Plymouth England submitted a paper to the Society of Economic Paleontologists and Mineralogists in 1939 – later part of a much larger work titled "Recent Marine Sediments" edited by Parker D. Trask US Geological Survey – under the subcommittee of Geology and Geography of the National Research Council in 1955.  Recent Marine Sediments was reprinted in 1968 (original printer London Thomas Murby and Company Fleet Lane – 1939) and is considered the most significant work on marine soil processes in modern time.

From H. W. Harvey – Biological Oceanography – pg. 150 of Recent Marine Sediments (1939)   

"Close to the bottom and in the surface layer of bottom deposits, bacteria are numerous.  They bring out changes in the organic detritus, converting it into "marine humus" which is its nature similar to humus formed on land, with age, that is, with continued bacterial attack, this marine humus undergoes further changes, the ratio of carbon to nitrogen in the organic matter in muds tends to increase with increasing depth, that is, with increasing age of the deposit." 

Without oxygen the resultant deposit it is called humus – with oxygen compost.  This humification process in the presence of oxygen generates nitrogen that is released as nitrogen gas or nitrates.  Carbon chain fragments the result of bond breaks of long protein chains is reduced to pieces no longer that bacteria in this oxygen environment utilize.  As such, they become humus a carbon rich substance over time.  This bacterial pathway is found today in backyard compost piles (which also generates heat) and the cool temperature terrestrial compost shed nitrate while a sealed high temperature compost sheds ammonia.  The agriculture community recognized this over a century ago (most likely far before this – T.V.) and in part why the discussion about "turning the compost pile" continues today.  (This I do myself with my two composts – perhaps with a slight modification that I dig up the bottom and replace with "green" or recently cut organic matter to prevent thick mats – four times over the year.  This is sometimes called the hot compost method as this tends to keep the compost warm or hot even in winter – T. Visel).

This composting process occurs in the marine environment as well which also can get hot – with one major difference it is surrounded by elemental oxygen or sulfate (compound oxygen) and now subject to sulfide generation much more of a problem when it is hot.  Although this known a century ago it is rarely mentioned in eelgrass studies (until very recently – T. Visel).  At times a marine humus undergoes "composting" without oxygen releasing enormous quantities of ammonia – and hydrogen sulfide – a plant toxicant.  In time the organic compost of plant cell tissue becomes depleted and humus the residue becomes carbon rich.  Students in Agriculture Education classes a century ago learned about composting – this is from West Virginia School Agriculture published monthly at Morgantown West Virginia ED Sanderson Dean, November 1910, No. 1, Pg. 16 from "Soil Studies" by D.W. Working – Free to all Agriculture teachers - Lesson VI Organic Matter in the Soil. 

"This organic matter in process of returning to its original state, feeds the bacteria that causes its decay; it increases the power of the soil to absorb and retain water, it makes the soil a more congenial home for the roots of living plants, it warms the earth with the fires of its own burning and absorbs heat from the sun, it loosens the tight clay soils and binds together the loose sands and gravel; it is the very vital and life – giving part of the soil."

This is similar to the eelgrass soils in which eelgrass gathers organic material and therefore begins composting beneath it.  In this case eelgrass becomes the composting "agent."  Again, the concept of marine composts (salt marshes can be considered a type of compost with plant tissue roots termed peat) has been known for quite some time – except for the influence of water temperature – hot seat water contains less dissolved oxygen, and "turning" occurs after dramatic energy events such as a hurricane.  Therefore, over time marine composts can become anaerobic during long periods of climate stability sometimes termed homeostasis or staying the same.  In habitat terms this period occurred in New England from about 1880 to 1920 – a period of great heat waves.  Here decades of relatively few storms did not turn natures marine compost which in heat became oxygen "poor" and then anaerobic, eelgrass collected organic matter below vast meadows that changed chemically when oxygen became "limiting."  This was also known a century ago and H.W. Harvey (1939) reviews marine composts sealed from oxygen the use of sulphate as an oxygen source and the formation of sapropel.  This composting process in the absence of elemental oxygen is often termed the near shore "black mayonnaise" and observed by coastal fishers and shore residents.  Notice the comments that appeared in a Boston Globe™ article that was printed November 26, 2011 by David Abel titled "Searching For The Right Cure For Cape's Algae Choked Waters" by coastal residents.

"Bourne – when the tide rolls out, the beaches on the west coast of Cape Cod often turned a shade of lime green, with splotches of a slimy substance that locals say resembles black mayonnaise and smells like rotten eggs."

And compared to H. W. Harvey description of "black mayonnaise" eight decades before – from Biological Oceanography (1939) and reprinted in 1955 and again in 1968 – as part of Recent Marine Sediments – Pg. 151 has this section –

"At a variable distance below the surface of marine deposits containing organic matter, conditions may become anaerobic and bacteria utilize sulphates and as a source of oxygen, setting free hydrogen sulphide. The material becomes blackened with iron sulfide.  A black layer commonly found some inches below the surface of sandy beach where this has occurred, and where subsequent oxidation of the iron sulphide sets free sulphur."

This is often the soils in which eelgrass lives – the very shallow organic rich soils which absorb solar radiation as a "sink" – creating at times super hot conditions that tend to lower dissolved oxygen levels.  At freezing 32o F(0oC), sea water can contain 12 milligrams of elemental oxygen 02 and can be considered saturated while at 30oC or (86oF) 7 milligrams of elemental oxygen is considered saturated in the same sea water.  At sea water temperatures of 90o F or more even with little dissolved or particulate organic matter oxygen requiring bacteria are dying replaced with bacteria that use sulfate as a source of oxygen – and in the process release sulfur – the smell of rotten eggs – mentioned almost every time associated with large shallow water fish kills. 

The National Pollution Discharge Elimination System usually limits sewage discharge Biological Oxygen Demand (largely termed wastewater today) to 10 mg/liter of BOD.  If the discharge remains as a unit compared to its receiving waters its BOD is enough to deplete elemental oxygen levels (without dilution) to zero, that is bacterial action to reduce available organics (bacterial food) will deplete all available dissolved oxygen.  In Connecticut – Appendix A: Discharges to Surface Waters DEEP – WPED – GP – 027 pg. 45 of 55 – rev 02/21/18 is noted as total suspend soils shall not exceed 30 mg/liter over a six hour period excluding those periods (such as heavy rains) in which a bypass occurs at a 100mg equals one gram – at 30 mg/liter it would take 33 liters of effluent for one gram or for one pound of organic matter (454 grams/pounds) for every 4,000 gallons of discharged at this level.  A sewage plant at 3 million gallons per day releases 750 pounds of organic matter each day.  That is why some permits contain different levels for suspended solids in seasons, for example the Draft University of Connecticut Wastewater discharge permit is October 1st to June 30th (cool water) is 15 mg/liter but July 1st to September 30th (warmer water) is only 10mg/liter.

Invariably the reduction of organic matter in the absence of oxygen results in a black substance that contains iron mono sulfides, (iron is an abundant metal considered to be nonlimiting).  In 1985 during a NOAA sponsored Estuary-Of-The-Month seminar at the US Department of Commerce 14th and Constitution Avenue Main Auditorium May 10, 1985 – sponsored by The NOAA Estuary Programs Office and the U.S. Environmental Protection Agency – under Battelle New England Research Laboratory Duxbury Massachusetts contract #68-03-3319, mentions the presence of sapropels – containing mono sulfides.

From the foreword - 

"The seminar was coordinated by Dr. J.R. Schubel, director of the Marine Sciences Research Center at the State University of New York at Stony Brook.  Dr. Schubel developed a program that included ten speakers, who addressed the natural, biological, chemical, geology, and physical processes that characterize Long Island Sound, the status of the Sound's living marine resources, and the effects of human kind on the Long Island Sound environmental and living resources" (edited by Victoria R. Gibson and Michael S. Conner – January 15, 1986).

The third presentation titled "The Benthic Ecosystem by Donald Rhoads – then of the Dept of Geology and Geophysics of Yale University (Dr. Rhoads and I first met in 1978 as part of a New Haven DAMOS dredge disposal project and later on rides to CT (1980's) from Cape Cod when my 1963 rambler classic was in the service shop at Meservey Garage, Chatham).  Our conservations at times included discussions about "black mayonnaise" a substance that was suffocating oysters in Tom's Creek Madison.  It was then also showing up in some of the shellfish surveys now on Cape Cod.)  His talk titled "The Benthic Ecosystem" contains this statement (1985) -

"Underlying the dysaerobic and anaerobic water one typically finds organic – rich black (i.e., sulfuric) muds that are sapropels.  These are rich in iron monosulfides.  The physical properties of these muds are distinctive and the best description that I have head of them is that they are like a black mayonnaise."       

These organic accumulations build rapidly in low oxygen waters because sulfate bacteria are not as efficient in composting as oxygen requiring bacteria (think about turning the compost pile) and when iron mono sulfides form it is a dying compost for oxygen marine life.

It is a period of heat and low oxygen that allows this sulfide rich organic matter to form – and is noticed by inshore fishers.  Terrestrial composters recognize the result of plant tissue reduction as humic acids or substances, including humics, calcium humate and fulvic acid.  The Agriculture Marketing Service of USDA – Humic Acids – January 27, 2006 Technical report Pg. (1) lines 37 to 45 briefly describes the relative speed between two composting pathways – one with oxygen and one without, ICF Consulting for the USDA National.

"The decomposition of organic matter in the soil is dependent on several factors, including the amount of available free oxygen, the amount of moisture present in the soil, and the temperature of the soil.  The amount of free oxygen determines aerobic or anaerobic microorganisms will conduct the decomposition process.  Aerobic microorganisms decompose organic matter at a faster rate (why we turn our compost piles – T. Visel) than do anaerobic organisms.  However, greater amounts of humic substances are found in soils produced by anaerobic organisms because in these conditions accumulation is favored over destruction of humic substances.  Although microorganisms need moisture to function, too much or too little water can decrease the rate of decomposition.  Increasing soil temperature leads to greater microbial activity and decreased humic substance content because decomposition is occurring at a faster rate than accumulation."

It is the accumulation rate by bacteria is the process of when hard bottoms become "soft."
This was observed in the New England inshore fisheries in the 1970's as we transitioned into a cycle of increased temperatures and lower energy events to mix or turn natures marine composts.  This is what Dr. Rhoads of Yale University mentioned at the end May 10, 1985 Long Island Sound Estuary of the Month Seminar, the increasing of marine composts, under conditions that would favor low or no oxygen bacteria, and composts on bay bottoms.  In heat they would become deeper – the rise and fall of sapropels.  Again from NOAA Estuary-of-Month Seminar Series No. 3 Long Island Sound (available from the National Technical Report Library).  Questions and response section pg. 148 from Dr. Schabel – "Don, do you want to add anything to that"

"Dr. Rhoads – Yes.  One reason I mentioned the importance of the Sapropels – these black iron monosulfite muds on the bottom – was the direct point that Peter raised (Dr. Weyl – T. Visel).  The system is so dynamic that to measure the change from year to year in dissolved oxygen and measured in the water column would take more money than we have.  It's not practical at all.

Given that kind of variability, what you need is a low pass filter, and on integrator, and   that's the sediment.  I suggest that a very sensitive index of the waxing and waning of this condition would be the map of where the sapropels terminate, whatever isobath (depth T. Visel) that might be, follow the edge of those sapropels – If they are encroaching upwards into the shallow water, it's getting worse.  If they're receding, it's getting better." 

Now if you replace the term "sapropel" for "compost" the impact of heat and low oxygen becomes clear.

Other similarities exit between terrestrial and marine composting – the amount and type of organisms that live in it.  Land composters recognize the importance of earth worms in the compost process – similar events occur in marine composts – although frequently termed "deposit feeders."  These assemblages change with the biochemical aspects of the compost and the availability of elemental oxygen reducers to consume them.  In times of energy (read mixing or turning) and cold conditions (read enhance dissolved oxygen availability) these marine composts support much life, shrimps, worms, clams, excavators such as that burrow into it much like terrestrial compost rove beetles and compost food for countless other organisms including pill bugs isopods – actually a relative of the blue crab a crustacean that lives on land.  Terrestrial composters have developed indexes as these composters respond to different bio chemical conditions.  The same occurs in marine composts, "Interpreting Long Term Changes In Benthic Community Structure A New Protocol" by Donald C. Rhoads and Joseph Germano (1986) these benthic composters have successional characteristics, identified stages I, II or III and that changes between them a measure or organic composting – termed biogenic processing from Rhoads/Germano (1986).

Pg. 301 –

"Spatial gradients between Stage 1 and Stage II" series can be very sharp, suggesting that and critical organic loading rate is exceeded. Stage III taxa are completely eliminated." 

This occurs as the marine compost is changed to a sulfide rich sapropel and often proceeds a bottom kill of aerobic life – a sulfide kill (the compost now contains little oxygen – T. Visel).  This is the most noticed perhaps that soft shell clams with high sulfide will pop out of the soil – and usually have black sulfide stained shells.  This is usually observed in a summer – warm water fish kill.  One 2003 Rhode Island account is found in article titled "Low Oxygen Levels Killing Off R.I. Clams" The Boston Globe, August 31, 2003.   

"When oxygen levels hit a low Thursday night, clams tried to find more oxygen, but couldn't said DEM marine biologist Chris Powell."  (See Appendix #1)    

Storms act to aerate marine soils – like a shovel to the compost marine soil and in the process cast up large amounts of clams and even lobsters onto the beach.  Storms tend to bring Striped Bass into the shallows to feed upon dislodged clams and worms living in natures marine compost turning or cultivation makes a natural chum bucket for those organisms cast out of it.  In the 1950's and 1960's trolling worms after a storm (when water had a grey tint) my father used what he called a "Niantic Bay Spinner" and a row boat (looks like a willow leaf spinner) that trolled the worm behind a spinning blade.  A pull on the oars made the leaf spin and an upwards movement.  I don't think Niantic Bay Spinners are made today but he had many of them and said after a storm it was very productive and made direct reference to worms after storms.

When I had Rhode Island red chickens (mostly free range) the second I put my hand on the shovel and headed for my compost pile – they came running from all directions waiting for the first shovels which then followed a rush to the area to pick up grubs, larva and worms.  These organisms could be found only in the compost by them I could not see most of them myself.

I realize that many marine researchers disfavor the term marine compost – instead of benthic sediment but the term marine compost is starting to be used Bangor Daily News, August 5th 2019 article titled "Its Time To Get Local About Marine Climate Change" and points out exactly the delicate balance between not enough organic matter and then too much – Parker Gassett of Camden Maine writes –

"Marine mud can be a compost pile with too much material decomposing, episodic spike in C02 result in local acidification events magnified beyond the global trends of climate change.  Living and photosynthesizing marine plants and algae have the opposite effect, taking up C02 and reducing acidification" and further –

"Maintaining a healthy balance between the compost pile and the garden of photosynthesis in coastal waters is remarkably important for protecting coastal ecosystems."

That balance can be in the presence of oxygen very productive habitats – the rapid cycling of organic matter food – productive for fisheries.

The composting soils, holds small clams, shrimps, organic grazers – worms, crabs, isopods a variety of food web organisms.  At times there is so much compost productivity it is outstanding.  It is therefore often a shock when oxygen becomes limiting and waters turn black from iron sulfides and a large fish and shellfish kill happens.  This kill is usually proceeded by good fishing – again this super charging of the food marine web was discussed and resultant higher bacterial demand for oxygen at the May 10, 1985 Long Island Sound Seminar Series #3 – again Donald Rhoads mentions the impact of overloading natures "marine compost."

Quoting Dr. Rhoads –

"I want to leave you with an interesting thought about oxygen – organism relationships.  Secondary benthic production can be very high in the hypoxic and dysaerobic zones, a phenomenon related to the abundance and high turnover rate of enrichment species that dominate these zones, this production (mainly polychaetes) may attract and support enhanced populations of benthic foragers such as demersal fish and crustaceans.  However, as the basinal low-oxygen conditions spread up the sides of the basin these commercially important populations may be compressed into ever decreasing aerobic environment.  The immediate perception may be one of increased catch per unit effort by fishermen.  As a result, maximum commercial yields may be obtained just before there is a crash in the exploited populations."

And this happened with continued Long Island Sound warming in the extended positive NAO in the 1990's.  As long Island Sound Waters warmed they exceeded the biological limitations of the lobster and habitat compression did occur reflected by Connecticut's lobster landings – an underwater "jubilee" that also occurs with the blue crab during hot stagnant conditions – lobster catches in Connecticut soared just before the crash. 

(US Dept of Commerce Project 3-IJ-168 Grantee State of Connecticut)
1985 CT Lobster landings was 1.3 million lbs
1990 (Habitat enrichment T. Visel) 2.6 million lbs
1998 (Habitat compression T. Visel) 3.7 million lbs
2003 (Stage 4 and nursery habitat failure T. Visel) 671,000 lbs

On August 12, 2012, surface water temperatures reached 75oF in eastern Long Island Sound prompting the shut down of unit 2 of Milestone nuclear plant.  Most researchers place lobster warm water tolerance at 69oF to 71oF.  But following the lobster died off (in 1998) blue crab populations soared in CT, they can live in warmer water (even over sulfide composts) because they can leave the bottom.  Most researchers give the blue crab a higher temperature tolerance – into the high 80's F.  When blue crabs face high sulfide bacterial composting, they leave the bottom during the oxygen minimum which when sunlight photosynthesis stops (often referred to as a "oxygen pump" - T. Visel) bacterial action draws from the day time "oxygen bank" and this bank runs out about 1 to 4 am in the morning.  This is when blue crabs leave the bottom for the surface to remain in waters with some residual oxygen reserves.  As the first light appears, the plankton oxygen pump restarts and large numbers of crabs clinging to docks poles, bullheads at the surface declines.  Blue crabs have another defense against low oxygen high sulfide events – a blue crab jubilee, here crabs approach the shore and may even crawl out at the edge.  This is a frequent occurrence in hot stagnant conditions and most jubilees occur in the hours just before drawn.  The jubilee term comes from the massing of fish and shellfish on the shore – making for an easy catch.  If long enough a jubilee (habitat compression event) may transcend into a dead zone – a fish and shellfish dieoff that is accompanied by the smell of rotten eggs.  This signals that the once productive cool water compost deposit is becoming a sulfide rich sapropel.  Although not using terrestrial terms of soil, composting or sulfate bacteria, the description by Dr. Kent Mounford Senior Scientist US EPA Chesapeake Bay Program comes close - Marine Weather Log Seminar, 1996 (describing the onset of a jubilee in Chesapeake Bay with submerged plants as a measure):
"I was dumbfounded and mystified until we came close to the water.  With the strong southwest wind at our backs, we saw the water was not actually clear, but white with countless billions of bacteria, the kind I was used to seeing in stagnant ponds where windrows of the Bay's once abundant sea grasses were decomposing.  These seemed to be the same sulfur bacteria, with the rotten egg smell that signaled the disappearance of oxygen from the water."
It is difficult to imagine the marine compost as oxygen deficient but that happens in heat and little energy – tides, waves or thermocline mixing.  A type of southern jubilee happens and composts begin to deepen.  These developing composts are observed by inshore fishers and coastal residents as a deepening soft organic deposit.  In areas with reduced energy and high heat, they emit sulfides we call them jubilees but overseas they are known as a "malaiques" and in 2002 linked to the weather climate patterns including the North Atlantic Oscillation or NAO (See Contribution of climate variability to occurrences of anoxic crises malaiques in the Thau lagoon" (southern France – Horzalloh and Chapelle Oceanological Acta, Vol. 25, Issue 2, 2002. Pgs. 79-86).
"The study shows that the probability of occurrence of malaiques increases with increasing temperature and decreasing winds in August both mostly associated to the high phrase of an index of (the) North Atlantic Oscillation."
In 1984, I would be asked to join an Environmental Review Team (ERT) effort to make recommendations for Holly Pond between the towns of Stamford and Darien, CT (King's Mark Environmental Review Team Report Holly Pond, May, 1985) by Richard Lynn ERT Coordinator in the fall of 1984.  We (the team) met on December 3rd at the site to review area concerns that the pond created for tidal energy in the 1790's had lost resource and aesthetic value, it had become shallow and increasing areas of water with more mud flats.  In late August nearby residents complained of sulfur smells.  In a historical review Holly Pond had been dammed and equipped with tide gates in 1796 to power a gristmill (John William Holly) and now had a greatly restricted circulation – a large organic matter trap and now contains black mayonnaise).  (The core data for Holy Pond would be conducted nine years later (See IMEP #15 Part 1, posted April 2, 2014, The Blue Crab ForumTM) in the catch basin.
The survey took place less than a year after leaving Cape Cod and Holly Pond problems more sea lettuce, bad smells, reduced depths and less fish sounded much like Green Pond observations on the Cape (Falmouth) and combined with the concept of a habitat history still fresh from conversations with John Hammond and an Oyster Pond dredging project – I wanted to look at the mud itself (See IMEP 68-A: Sapropel and Habitat Impacts to Fisheries 1800's to 1900's) with cores to examine the type and history of infilling.  To me, the reduction of energy (the dam) and increased organic loading of leaf matter (much of it most likely from road paving) and was just a huge marine compost deposit. 
Much of my interest was the prospect of layers – shellfish populations that over time were being buried over time.  The most direct approach was to replace tidal energy (removal of the dam) or dredge out this compost.  Similar to the impact of opening new barrier beach inlets, (or the closing of them) changes in energy are often reflected in distinct layers in core studies.  This was the "habitat history" condition of John Hammond's Oyster Pond River dredging project review in 1971 (See IMEP #68-A: Sapropel and Habitat Impacts to Fisheries, posted December 12, 2018, The Blue Crab ForumTM) as sand layers buried those of organic matter.  Unfortunately, the study in 1985 did not have the funding to conduct in depth Holly Pond core studies, but those options were mentioned.  I thought Holly Pond to be an excellent site to study the impact of this compost in high heat – low energy conditions.  One of the key indicators was that key indicator was that sulfide formation was occurring was the absence of eelgrass.  This signal was to show that this composting material (black facies) had ceased to be suitable soil for it.
In reviewing the fisheries section of the 1985 report, the comments and observations were very similar to working with Bill Bauknecht Green Pond (See Falmouth Mass: A dramatic increase in sea/lettuce followed by a sulfide bottom kill) – so I put it in on page 27. 
"The rapid growth of sea lettuce (Ulva in a salt pond Green Pond, West Falmouth, Cape Cod) created anaerobic conditions with resulted in the death of winter flounder, over 400 bushels of softshell clams, and blue crabs."       
And although I mentioned movement of these organics from low oxygen to high oxygen areas removing dense mats of macroalgae, dredging and direct aeration – oxygenation of pond sediments descriptions of these suggestions did not appear in the final report, I inquired a couple of years later and found out that they did not coincide with policy goals or something to that effect, I suggested a "habitat" restoration project with these suggestions in 1985.
1)   Reduction of nutrient loading – (much of it was hard organics leaf matter)
2)   Mechanical removal or harvesting of excess vegetation.  (Perhaps with small trawl nets).
3)   Dispersal of unreduced organic debris from oxygen depleted regions to oxygen – sufficient areas to complete aerobic respiration – this was termed by hydraulic side casting – often just resuspension or jet pump stream was enough to move this sticky compost – this is frequently termed "thin layer deposit" today.
4)   Dredging and containment programs for Holly Pond, I had completed a program for dewatering sapropel by use of baffles a marine like grid to separate water from a Mud Cat™ dredge for Al Surprenant (now Cape Cod Oyster Company) in the early 1980's.  (See Three Dimensional Oyster Aquaculture – A Study of Little Oyster Island in Osterville, Mass prepared for Albert A Surprenant – Smithfield Fishers Lincoln RI – 51 pages, March 1981).
5)   And Soil Aeration – oxygenation of pond sediments – hydraulic jetting.
This was the hydraulic jet manifold – from the Cape similar to a leaf blower but using peat aeration processes to inject sea water (cold water program) with oxygen to boost mineralization – or bacterial respiration (See IMEP #77-A: Pattagansett River the Dead Soils, posted on May 29, 2020, The Blue Crab Forum™).  This action could occur during cold stormy periods and could leave a "habitat history" in core samples.  Although not part of the original Holly Pond ERT 1985 Holly Pond would be cored in a later study in 1993 (Vibra Cores).
CWF -310-R CT DEP Long Island Sound Research fund – funded 8/26/93 – completed 8/31/01 = released to records 2011.  Project Title Rates of Sediment Accumulation in Coastal Coves on Fisher's Island Sound.  Principal Investigator Peter C. Patton Wesleyan University.  The Holly Pond Cove section begins on pg 23.
Holly Pond Stratigraphy     - Dr. Peter Patton Wesleyan University (1993) pg. 23   
"The substrate of Holly Pond consists of gelatinous, organic rich mud of the black mud facies.
The diagram illustrate that the mud deposit is up to 8 meters (26 feet approx.) thick at the mouth and thins landward to 4 meters (13 feet approx thick at core (station) HP-1."  (Holly Pond 1).
Perhaps HP #3, a vibracore, gives a rare insight of what a slice of the compost pile looks like in a low energy restriction pond with terrestrial leaf matter from a river – my view Tim Visel.
Holly Pond Core HP # taken 7/13/93 at 10 am center of pond water depth 1.68 meters total core length 816 cm pg 24 rare profile as from Patton document 8/18/01 as reported as core depth/profiles of 14 district sections/layers.  (They are detailed below T. Visel).
Layer 1      0-25 cm black organic rich mud
Layer 2      25 to 30 cm shell layer (no type specified)
Later 3     30 to 46 cm black mud
Layer 4      46 to 50 cm sand with scallop shells
Layer 5      50 to 150 cm black mud, one large oyster shell at 65 cm
Layer 6      150 to 153 cm reworked shell debris
Layer 7      153 to 170 cm black mud single gravel clast at 161 cm
Layer 8      170 to 180 cm sand and oyster shell debris
Layer 9      185 to 545 cm black mud single pebble at 222 cm
      Fragments of wood at 337 cm, detrital plant fragments at 40 cm    
Layer 10   545 to 560 cm black mud bound by plant roots
Layer 11   560 to 713 cm black to brown mud wood fragments at 713 cm
Layer 12   713 to 746 cm brown mud bound with plant roots
Layer 13   746 to 800 cm interbedded layers of coarse sand and detrital plant fragments
Layer 14   800 to 816 cm yellow – brown mud
This is a bacterial "composting" process without the compost pile.  In hot weather it can be expected that areas of "dead zones" of low or no elemental oxygen will grow – while with cooler or cold sea water often sees them shrink.  If organics accumulate as if during low coastal energy or drought they can become sapropelic in heat, and subject to sulfate reducing bacteria, the shallow water sulfur cycle which is noted by sulfur smells of rotting eggs.  This is often the habitats of shallow water eelgrass that is harmed by high temperature release of toxic sulfides – much of it from the compost in which it lives.  In high heat and low oxygen organic matter now turns deadly.  We have an excellent account of the process directly impacting plant growth one century ago from Nichols – The Vegetation of Connecticut pg 525 (Bulletin of the Torrey Botanical Club Vol 47 New York, January 1920 – The New Era Printing Company Lancester, Pennsylvania) by George E. Nichols – The Connecticut Coast 1920.  My comments (T. Visel).

"At ordinary low tides these tidal flats of the lower letteral present a surface of soft, blue-black, ill smelly mud – an area in which, except for local colonies of eelgrass or salt marsh grass (Spartina glabra) (Note: now recognized as alterniflora today - T. Visel).  Seed plants and attached algae are practically absent.  At certain seasons these muddy flats may be destitute of visible vegetation of any description, but at others be bare mud at low tide is littered with loose sheets of Ulva and tangles of Enteromorpha, which may cover the ground so thickly that, when viewed from a distance, the surface appears verdent green." 

Now compare this 1920 observation to the 2011 article quote from The Boston Globe Dave Abel article – they are incredibly the same. 

"Searching For The Right Cure For Cape's Algae - Choked Waters" Dave Abel – November 26, 2011 – The Boston Globe.   

Bourne when the tide rolls out, the beaches on the west coast of Cape Cod often turn a shade of lime green, with splotches of a slimy substance that locals say resembles black mayonnaise and smells like rotten eggs.  In the warmer months, a film of algae spreads through the harbor in Cataumet and the opaque waters turn a capper color, veiling the little – life left on the seabed.  "There can be so much algae in the water that they look like huge lily pads, like you can walk across them on the water."

For nearly a century this marine composting was not a recognized habitat feature of the shore – even though these composts were once utilized in terrestrial soil enrichment for hundreds of years.  One of the agencies that rested and wrote about marine manures was the nation's first Agricultural Experiment Station here in New Haven, CT.  Jenkins and Street (1917) Manure from the Sea Bulletin 194, Connecticut Agriculture Experiment Station, New Haven, CT pg. 11.

"Marine Mud – this is mud taken from flats at low tide or cast up on the shore of an inlet.  If it is put in heaps above the highest tides and leftover winter to drain and weather, if fails to a fine powder, but if heaped in summer it is apt to bake into hard lumps.  In some places, vast quantities of small shells, ground fine by the waves, are cast up with the mud.  Such mud may contain 3 to 4 percent of carbonate of lime, which increases the value of the mud."

Only in the past three years has the term sapropel reappeared in journal articles and its relationship to eelgrass.  (See Meyer and Lindbo – Second Edition, 2018 – Interpretation of Micromorphological features of Soils and Regoliths, Section S.S. Dry Gyttja and Sapropel has this section,

"Sapropels are subaqueous layers formed at the bottom of nutrient – rich waters under anaerobic conditions.  Sapropels contain various amounts of more or less recognizable organic debris, and they are often highly enriched in sulphides, occurring as Fe-mono sulphides or pyrite colours of sapropel horizons in the field are typically black changing to grew upon drying.  In marine settings sea grasses such as Zostera spp. (Eelgrass – T. Visel) may provide considerable amounts of plant residues and tissue to surface and near surface horizons."

And also –

"In marine intertidal zones, organic layers may also contain shell fragments, algae and remains of higher plants (commonly referred to as tree leaves – T. Visel).

This is what makes our Connecticut sapropels "sticky" at times.  Oak leaves have a very high wax content that is undigested by anaerobic bacteria so they leave these waxes "behind."  These sapropels have high paraffin content especially in areas that obtain vast amounts of oak leaf residues.  In high salinity areas oils from plankton give sapropel a jelly like consistency.  These materials can form Kerogen (i.e., "wax birth") the foundation of petroleum and natural gas.  When disturbed sapropels may produce a sheen in the water indicative of Type 1 Kerogen – Algal – Sapropelic formation – they are called "humic sheens."  These sheens resemble petroleum but usually have no "smell" are the result of natural composting.  To the individual observing this may immediately think of oil pollution but humic sheens (rainbow color) are caused by composting bacteria.  A simple test will show the difference, humic sheens when disturbed tend to break into chunks or pieces, while a petroleum spill when disturbed will try to reform or close up the created opening. 

Sapropels have been shown to contain phytol a diterpene alcohol and abundant wax esters linked to terrestrial plant composting processes.  Researchers today are researching sapropels for specific plant life "signatures."  Key to the formation of carbon chain molecules was the presence and chemical reactions of sulfate reducing bacteria (SRB) and the estuarine sulfur cycle.  Claude Zobell (1939) paper titled "Bacteria In Marine Sediments" (See Recent Marine Sediments, 1955. edited by Parker D. Trask) comments on the presence of sulfur bacteria eighty years ago,

"Many types of bacteria influence the sulphur cycle in sediments.  It is not unusual to find from a few thousands to a few million bacteria per gram of mud that liberate hydrogen sulfide (H2S) from Sulphur – continuing proteins, and those that reduce sulphates to H2S are widely distributed in marine sediments.  The hydrogen sulfide H2S may combine with iron or other substances, it may be oxidized to and deposited as elementary Sulphur or it may be oxidized to sulphates.  The occurrence of sulfate reducing bacteria in the oil-well waters may be of special significance."

As sulfate is dissolved in huge amounts in sea water – the remains of when sulfur life was dominant it is considered non-limiting for sulfate reducing bacteria in shallow hot waters.  Therefore, it is often (almost always) that eelgrass die offs occur in the upper reaches of estuaries first, as these soils transition to a building sulfur cycle composting process and become sulfide rich.  These are the waters that can become very hot – reducing oxygen (elemental) levels below BOD levels at which this favors sulfate bacteria and causes a bacterial war (See EC #7 Salt Marshes – A Climate Change Bacterial Battlefield, posted September 10, 2015, The Blue Crab Forum™ Environmental Conservation thread).  Here, the presence of sulfate becomes the "go to oxygen source" and when that happens eelgrass plant viability declines.  This is when the biology of eelgrass damages its ability to live – it gathers organic particles as it grows creating an organic soup or culture both media for SRB.  Many researchers have noted the ability of eelgrass meadows to rise trapping fine particles of silt, clay and bacterial mucilage on it leaves but also organic debris between its blades – eelgrass meadows have a tendency to rise over time.  This process has a direct effect upon soil chemistry in heat, as low oxygen now favors the formation of sulfide a known plant toxin.  Sulfides themselves react with metals (sulfate reducing bacteria are commonly referred to as "ore builders – T. Visel as the ability to concentrate metals sulfides was one investigated by EPA as a way to neutralize mine waste water.  When re exposed to oxygen as during a severe storm deposits purge sulfuric acid which destroys plant roots.  In cold periods or those following a major storm or series of storms sulfuric acid is released into these organic composts as a quick burst.  These composts now become acidic and deadly to eelgrass in hot water a natural breeding ground for fungus.

The remains of organic matter have different bacterial routes – the thin walled "easy meals" of plankton and harder to digest cellulose of woody tissue such as leaves – the "tough meals."  The Role Of Sedimentary Organic Matter In Bacterial Sulfate Reduction The G Model Tested, by the Dept of Geology and Geophysics Yale University, New Haven, CT – Joseph T. Westrich and Robert A. Berner (1984) reviews this aspect.  The stimulated rate of sulfate reduction in the sediment measured by the S radiotracer technique. 

"The stimulated rate of sulfate reduction was in direct proportion to the amount of planktonic carbon added.  This provides direct confirming of the first order decomposition or G model for marine sediments and proves that the in situ rate of sulfate reduction is organic matter limited slower sulfate reduction rates resulted with oxically degraded plankton rather than fresh plankton was added."

I have seen this on Cape Cod in sections of Lewis Bay in 1981-1982 described by inshore fishers as oatmeal, deposits of leave stems on the bottom – millions of them but no leaf material – these stems (I thought at the time oak leaf stems) had no leaf material – just the stem – the thinner "softer" meal had been consumed first leaving countless stems behind.  (Concerns then was once a productive Quahaug bed but now covered by leaf pieces and stems – See IMEP #28: A Caution Regarding Black Mayonnaise Habitats, posted October 2, 2014, The Blue Crab ForumTM).

The eelgrass on Cape Cod was not doing well it was sloughing off huge amounts of tissue (it naturally dies back in winter) and that was on the beaches and in towed gear.  When these wracks were examined (See IMEP #61-B Buttermilk Bay, posted April 3, 2017, The Blue Crab ForumTM) black spots or sections could be seen, these areas were brittle and blades broke easily.  It appeared that the blades were dying in sections with longer blades breaking off, wrack looked like cut noodles rather than long green blades.  This is a problem when fungus attacks terrestrial plants in most hot conditions.  This is often referred to as leaf spot or black leaf disease traced to crops that as a monoculture easily spread fungal spores.  For example, the pathology of leaf spot disease in sugar beets Beta vulgaris was studied in the early 1900's as a fungal attack but resembles the fungal attack upon eelgrass a century later.  A US Department of Agriculture Report #69 1900 Washington GPO 1901 Progress of the Beet – Sugar Industry in the United States in 1900 – Report of Special agent Charles F. Saylor, page 96, contains a section on leaf spot:

"Leaf spot is produced by a distinct and well known fungus, Cerospara beticola (Still causing sugar beet damage – T. Visel) which attacks the leaf blades and petioles (leaf stalk) producing brown spots with somewhat purple edges.  These spots are at first small and nearly round, but increase quite rapidly in size, and when two or more spots meet, an irregular dead brown spot is produced, which is brittle and which often breaks and falls away.  Eventually the whole leaf becomes affected and dies.  The author or older leaves are attacked first, and as they die, new leaves are put out from the center of crown.  They result of this process is that the crown tends to elongate and assume somewhat the appearance of a pineapple hence the charge in shape is often spoken of as the "pineapple effect of leaf spot disease."   

Compare the above to those of Clarence Cottam and C.E. Adding "Present Eelgrass Condition and Problems on the Atlantic Coast of North America – Transactions Of The Twelve North American Wildlife Conference, February 3, 4, and 5th 1947 – pg 392 has this section – "The Disease."

"Many theories have been advanced in the effort to determine the probable cause for the abrupt destruction of eelgrass.  The evidence accumulated to date points to the mycetozoan Labyrinthula, a low form of fungus.  Renn (1936) demonstrated the ability of the organism to reproduce rapidly, to spread from leaf to leaf and to produce the characteristics streaking and blackening of the leaf."

And further – my comments (  )

"During the spring (May) of 1944 the beds at Newburyport (Massachusetts) were healthy and vigorous.  Only a few streaked leaves were observed, microscopic examination if the leaves revealed only scattered inactive labyrinthula.  By the latter part of July and August however (much warmer general conditions – T. Visel), the beds at Newburyport were degenerating rapidly most of the older leaves were blackened and much of the new growth was streaked." 

Fungal attacks on plants are reported in heat, with millions of fungal spores released in damp moist conditions.  These fungal attacks are found described as "black streak" or "black leaf disease."  It is a sign of habitat decline for eelgrass and one related to climate and soil conditions.  Fungal damage to terrestrial crops is often associated with a pH drop – below 5 pH but oak leaf residues leaf material has a pH of 3.8 making an acid compost in shallow water that is already acidic (some terrestrial composters use oak leaf compost to produce acid soils).

In heat and low oxygen conditions it is the shallows that this fungal attack often occurs first.  It is also the shallows that obtains greater solar radiation – and heat drives eelgrass soils to become sulfide rich.  Although much as been written about the need of light for eelgrass, the first die off almost always happen in the shallows first – areas that obtain the most intense sunlight.  These same areas are now subject to a bacterial war in the soil as hot water holds less oxygen as these oxygen requiring bacteria die off replace by nitrate reducers and then sulfate reducers.  This bacterial conflict has dire consequences for eelgrass soils – the process of reserving or holding organic matter now works to increase soil sulfides and the smell of "rotten eggs" a condition that quickly spoiled range eggs in the hot 1890's.  These shallow soils now contain a "sulfuric acid potential" and when oxygen is reintroduced – a cold snap or storm that increases oxygen in the water (mixing) these soils now purge sulfuric acid which can damage roots.  For a short time, eelgrass has the ability to redirect oxygen to its roots to keep acid oxidizing bacteria alive around its roots (necessary for nutrient exchange) but not for long – a combined fungal attack on its leaves reduces this oxygen capacity – its root shield with acid attacks the plant suffers root damage, it dies off – it wastes away, perhaps a better term would be it rots away. 

This description when compared to habitat cycles is most notable if colder and wetter (lower salinity) conditions exist which may see the return of Ruppia – a submerged plant which prefers marine soils with lower salinity.  It is possible to see Ruppia replace Eelgrass in the same area as the US Fish and Wildlife Currituck Sound Study (See Back Bay – Currituck Sound Data Report 1969) records the rise and fall of vegetation types was both climate (temperature) and energy (inlet water exchange) related to long period climate cycles such as the Northeast Atlantic Oscillation or NAO. 

The NAO offers an explanation of the expansion of the healthy clean and green eelgrass expansion of the 1950s and 1960s. Here in cooler temperatures and many storms shallow estuarine soils were naturally cultivated removing humic acids and oxygenating soils in the same "turning" process of land composts.  This was evidenced by expansive growths of the following clean and green eelgrass – often to the dismay of small boat shellfishers.  That can be compared to the 1980s and 1990s a period of higher temperatures, few storms and stagnant soils – surrounded by ammonia fed algal "soup" that coated eelgrass leaves – the so called "brown and furry" eelgrass blades.  (In 1981, on Cape Cod I would examine this coating referred to as a "slime").  These observations appear in some of the fist eelgrass studies, the shallow water eelgrass died off before the deeper – cooler and more energy prevalent eelgrass meadows lived longer. 

These soils (helped by eelgrass trapping organic matter and the presence of sulfate reducing bacteria) now became toxic to established eelgrass growths – what was a suitable soil in cold storm filled periods – depleted of organic matter was turning toxic in a composting soil in heat with little soil cultivation.  These soils even under water became "stagnant" and sulfide rich.  As sulfides accumulated in them sulfuric acids could be formed resulting in acid sulfate soils, long known in the centuries of agricultural use of them in to enhance crop production.  Some of the first direct observations of sulfide toxicity to submerged vegetation came from warmer climates including Tampa Bay Florida.  Hare organic matter in heat produced ammonia and sulfide as bacterial populations changed in the soil.  It is thought that oxidizing bacteria that turned ammonia into less toxic nitrate could not because they lacked the needed oxygen to complete the process.  As oxygen is limiting in hot water any biological demand for organic matter consumption resulted in an increase of anaerobic composting – a sapropel.

It is this transition that bacterial changes greatly influence sulfide and sulfuric acid formation. The chemistry the soil changes from positive to negative for eelgrass and is related to salt marsh outs, die offs, forest die offs, black layer disease in turf – all have a sulfide – sulfur connection.  In 1994 Paul R. Carlson, Jr., Laura A. Yarbro and Timothy R. Barber authored a paper in the Bulletin of Marine Science, 54 (3) pgs 733-746 – "The Relationship of Sediment Sulfide to Mortality of Thalassia Testudinum in Florida Bay" which included soil observations as sediment and indicated that sulfide might be part of a greater synergist stress – a combination of several factors influencing the condition of the soil, hypoxia, rhizome attack by bacteria acids and pathogens (such as fungal attack – T. Visel).  As the soil quality improves roots can live deeper and has a greater root mass – while declining soil quality was shown by higher sulfide levels and less or declining root tissue mass (a root dieback T. Visel).  It is here the submerged plants exhibit a compensating feature to protect is bacterial rhizome (root shield – T. Visel) protection, the ability of gas conducting tissue (aerenchyma) to release oxygen into its roots.  If this does not happen "a sulfide deadline" starts to kill root tissue in the soil.  (This is noticed by a blackening of the root tissue).  If this action produces sulfuric acid (this process although known for a century, or more is just now being mentioned in eelgrass reports – T. Visel) then this opens the door for fungal attack.  High amounts of ammonia fuels algal growth which can coat eelgrass blades reducing its ability to conduct photosynthesis and move sufficient oxygen to protect its roots.  All these conditions would indicate a soil structure not favorable to the growth of eelgrass.  This is a section of Carlson et al paper (1994) comments by T. Visel within   
( ).  (Relationship of Sediment Sulfide to Mortality of Turtle Grass).

Conclusions – Pg. 744

"Porewater sulfide concentrations of Florida Bay seagrass beds were higher than those measured in other Florida estuaries.  Sulfide concentrations in apparently healthy seagrass beds were highest in fall (when the deadline is closer to the surface – T. Visel) and might have caused chronic hypoxic stress of Thalassia roots and rhizomes, contributing to seagrass die off.  High power water sulfide concentrations measured in dying areas of seagrass beds suggest that sulfide produced by microbial degradation (bacterial composting – T. Visel) of dying Thalassia might exacerbate stress on adjacent surviving seagrass.  The occurrence of elevated pre-water concentrations before necrosis (black spot disease T. Visel) of Thalassia leaves and shoots (root tissue digestion or stunting T. Visel) became visible during one die off episode.  Suggests that pore water sulfide concentrations might be used in surveys of Florida Bay to locate areas of insipient die-off."

Although the formation of sulfuric acid from sapropels was studied in agriculture applications as early as 1880s by the New Haven CT Agricultural Research Experiment Station, this aspect has been neglected to eelgrass (seagrass) soil health.  This is an except from an 1880 Connecticut Agricultural Experiment Station Bulletin #37 – Feb 14, 1880, a mud sample was sent for analysis from Essex, CT – sample 322 – an estuarine sample set back of the tide and comment about the sample from J. I. Stevens of Essex, CT –

"Unlike stable manure and ordinary composts the mud contains a considerable of sulphuric acid in the form of sulphate of lime.  The mud contains .46 percent sulfuric acid, while stable manure has .10 percent or less."

Comments include experiments of Mr. Steven's harvesting the muds behind dams for soil treatments – and from the description a monosulfuric rich sapropel – and likely capable of purging a burst of sulfuric acid once exposed to air – with negative plant growth results.

The comments leave little doubt the presence of sulfides (smell) sapropelic characteristics (drying to lighter color) and toxic impacts to plants – possibly from a burst of sulfuric acid – termed Acid Sulfate Soils today from 1880 as noted by S. W. Johnson Director Connecticut of Agriculture Experiment Station –

"Mr. Stevens also remarks" our mill ponds a few miles back from the river, contains a rich, black mud, quite deep and with a very strong smell.  It has been tried on various crops but kills everything.  After being hauled and dried it turns from black to white and puckers the mouth like alum" – Director Johnson responds, "The astringency (acid) here referred to is due to soluble salts of iron or alumina.  Composting with a small proportion of slacked lime will decompose these salts and render the black mud a safe and serviceable application."

Thirty-seven years later, Bulletin #194 July, 1917 from the Connecticut Agricultural Experiment Station New Haven, CT "Manure from The Sea" by E. H. Jenkins and John Phillips Street contains this section shows a marine mud sample at .53 percent sulfuric acid.

And on Pg. 11 contains this section,
   
   Marine Mud –

"This is mud taken from flats at low tide cast up on the shore of an inlet.  If it is put in heaps above the highest tides and left over the winter to drain and weather, it falls to a fine power, but it heaped in summer it is apt to bake into hard lumps.  In some places vast quantities of small shells, ground fine by the waves, are cast up with the mud.  Such mud may contain 3 or 4 percent of carbonate of lime, which increases the value of the mud."   

And Bulletin #709 of the Connecticut Experiment Station Tidal Marshes of Connecticut and Rhode Island reviews the pH of organic matter below salt marsh surfaces – one exposed to air oxygen becomes very acidic – from Hill and Shearin (1970) pg. 10 contains this section (samples drained and exposed to air (T. Visel comments in ( ) ).

"The dramatic increase in acidity after draining and drying is caused by the oxidation of sulfur, a process called sulfur acidity.  The stage for oxidation was set earlier in a wet oxygen poor environment (soil is applicable here T. Visel).
Here, anerobic sulfur reducing bacteria extract sulfate from sea water, use it, and then concentrate in the sediments (again the term soil for sediments T. Visel) thus, the sulfate of sea water is transformed biologically and chemically to black hydrous iron sulfide and hydrogen sulfide gas.  The blackish sub surface sediments and rotten egg odor of the marsh are well known.

"The sulfides in the wet environment now lie ready to be transformed.  As marshes are drained or sample dried, oxygen permeates the sediment and sulfide is converted to sulfate, some sulfate combines with hydrogen and produces sulfuric acid and low pH.  If however, the sediments (again think soil – T. Visel) contain abundant shells, the acid generated during oxidation and drying is neutralized by alkaline carbonate in the shells."

The agriculture use of marine composts would be detailed by all the New England Agricultural Experiment Stations and mentioned in many period agriculture reports.  They frequently mention the use or need of calcium naturally (bivalve shells) dug up with these deposits to offset acidic conditions.  As early as the 1780's, farmers were detailing its use (See IMEP #68-A: Sapropel and Habitat Impacts To Fisheries 1800's to 1900's, posted December 12, 2018, The Blue Crab Forum™ Fishing, Eeling, and Oystering thread).  The most compelling evidence of its use came from a talk by William Clift of Stonington, CT before The Rhode Island Society for the Encouragement of Domestic Industry and the Rhode Island Horticultural Society Sept 14, 1854 Providence, Rhode Island describes this marine composting process and even mentions the role of eelgrass collecting it – this is a portion of Rev. William Clift's speech of Stonington, CT titled "The Agricultural Wealth of Rhode Island" delivered at the RI Horticultural Society Fifth Industrial Exhibition about the wealth of soil and treasures form the sea, sea weeds and marine composts – pg. 7 of the speech contains these quotes –

"Square leagues of the eelgrass may be found, in all our shoal waters, growing in great luxuriance.  These seaweed fields are, for the most part, made up of vegetable deposits, brought down in the currents of brooks and rivers, from their remote sources in the mountains, and highlands.  The leaves of the forest, and the fine vegetable mounds, along the banks of rivers, broken off by the current, find their way into the water, and are barned onward to the bays, and cover the bottoms, with a rich black deposit.  The richest portion of New England has thus been swept off by here rivers, and now lies under water, or is just emerging from it in the salt marshes, along the shore.  No bottom land of the west is richer that this deposit.  If it could be raised above the water, it would raise crops, to rival any in the world."

And further –

"The marine deposits, in the bottoms of your bays, creeks, and rivers are made up, very largely of these decayed weeds, and could not fail to prove a valuable fertilizer."     

But William Clift's suggestion would wait 157 years before this suggestion would be seen in print.

In a final report on fertilizers and soil conditioners – European Union EGTOP/2/2011 Section 3.4 Sapropel – Final Repo