IMEP 135 Part 1 The Pitar and Lucina Clams

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IMEP #135 Part 1: The Pitar and Lucina Clams
The Pitar and Lucina Clams and Sulfur Compounds
Marine Soils and Habitat Succession From Climate
"Understanding Science Through History"
The Cultivation of Marine Soils – A change in clam and plant species
Pitar and the Puerto Rico Clam Lucina pectinata As Succession Indicators
October 15, 2019 - Revised to March 2022
This is a Delayed Report
Viewpoint of Tim Visel – No other agency or organization
January 2023
Thank you, The Blue Crab Forum™ for posting these Habitat History Reports
Tim Visel Retired from The Sound School – June 30, 2022


A Note from Tim Visel

To fully understand habitat change for many benthic species, you need to include the sulfur cycle.  That was one of the main concepts that John Hammond pressed during our meetings over 40 years ago.  To be honest I had not read about or had knowledge of the many features of this chemistry.  I knew that before oxygen became abundant sulfur was a respiratory pathway.  That is how sulfur found its way into organic residues such as coal and why so much sulfate is dissolved in sea water. 

The importance of sulfur is now evident in how marine habitat succession (aging) happens along our coasts.  Most of the negative aspects of fish run decline, coral bleaching, salt marsh dieback, fish kills and seagrass die offs have a connection to sulfur or its compounds.

The concern about sulfur is not new.  Hydrogen sulfide has been known to be a poison for hundreds of years.  Its odor has been associated with death with a frequent comment of "the smell of rotting eggs."  Mr. Hammond's research involved the cultivation of bay bottoms and the aspects of "new sand."  He watched barrier beach spits on one of the largest habitat laboratories, Nantucket Sound and the Atlantic Ocean.  Mr. Hammond described massive changes in the barrier Island complex known as Monomoy off the coast of Chatham Mass.

In his explanations of how temperature and energy could alter coastal habitats he frequently offered Monomoy as evidence of such changes.  A recurring topic was "new sand" storm driven sands washed by waves and new perhaps to the surface.  It was in this "new sand" that clams often set the heaviest and if not, additional storm driven sand covered them matured into a fishery.

The observation of new sand or placing a layer of sand can be found in the historical shellfish literature pertaining to increased setting.  Experiments were under way in Clinton Harbor as early as 1902 with reports of heavy soft-shell clam sets in layers of new sand, free of organic residues.  David Belding on Cape Cod conducted shellfish experiments on Monomoy (a frequent John Hammond reference) and also detailed department experiments with "new" or graded soils having good sets in the 1910s.

The impact of the sulfur cycle upon marine soils would not be a research topic again for another century.  In the middle and late 1990s, researchers in Florida would link the die off of seagrass (turtle grass) to sulfide build ups in muddy soils. 

The formation of sulfur compounds was connected to soils with high organic content that was also frequently void of clams or seagrass.  In southern New England during periods of low storm activity eelgrass can form a peat, a plant tissue matrix of stem, leaf and root debris that is spongy to the touch.  Below the peat is an indicator of soil succession – the burial of clams and increasingly pungent smells of hydrogen sulfide.  This happens faster in warm water as dissolved oxygen levels are lower and why perhaps some species of clams in southern waters have adapted themselves to live in soils higher in sulfide.

Two non-commercial species of Clams Pitar morrhuana and Macoma balthica appear to utilize symbiotic bacteria to detoxify sulfide into thiosulfate.  To oxidize sulfide into thiosulfate clams were able to access oxygen with the symbiotic bacteria that utilize nitrite and nitrate as oxygen acceptors.  (Wilmot and Vetter 1992) The clam Lucina pectinata, which is prevalent in Puerto Rico, is able to oxidize sulfides in the presence of elemental oxygen O2 and compounds of oxygen in low dissolved oxygen making it unique in its ability to live in high sulfide soils.  (See research of Juan Lopez-Garriga at the University of Puerto Rico Mayaguez – A model for hydrogen sulfide.)  The build-up of sulfide and how nature removes it from marine soils as critical habitat feature to benthic species including marine grasses - my view, Tim Visel.   

The Marine Soil Sulfur Cycle

The successional aspect of marine organisms living in marine soils is connected to energy systems and climate/temperature.  These factors govern oxygen accessibility into marine soils and therefore influence plants living on the edge of the sulfur cycle.  Temperature can increase or decrease dissolved oxygen in sea water as submerged peat soils – i.e., those that support salt marsh plants, as eelgrass and even mangroves are able to live in sulfide habitats, few plants can.  Marine soils are saline, and sulfide rich at times and often containing heavy metal sulfides.  Sulfide is also a plant toxin.  For marsh plants including Spartina alterniflora have the ability to move oxygen to its roots – even in high pore sulfide soil conditions (Oxidation Of Sulfide By Spartina alterniflora Roots Limnology Oceanography 1999).  The stunting of Spartina alterniflora has been shown to be a factor of sulfides (King et al., 1982 – Relation Of Soil Water Movement And Sulfide Concentration To Spartina alterniflora Production In Georgia Salt Marsh Science 218 61-63) toxicity.  The movement of oxygen to roots and to leak it out help keeps oxygen bacteria alive but also helps detoxify sulfide making plants more sulfide tolerant.  One of the first reports to examine this sulfide/oxygen relationship to salt marsh plants was conducted by a colleague at The Sound School, Eric Yuhas.  His research "The Importance of Oxygen Diffusion Rates and Chemical Oxygen Demands in Influencing Vascular Plant Zonation On The Salt Marsh" was presented during a 1983 New England Estuarine Research Society meeting.  Lower oxygen availability is a strong indicator of increased sulfide formation and plant health.  Warm water holds less oxygen and high marsh sulfide levels can happen in late August when seawater can surpass 100oF on marsh peat surfaces (See EC #17-B for the NEERS abstract E. S. Yuhas 1983, posted April 12, 2019, The Blue Crab Forum™ Environmental Conservation Thread). 

Sulfide conditions is also an indicator for declines in shellfish meat quality – the first oyster sulfide – oyster meat quality studies were done nearly a century ago in the York River Virginia (See "Ecological and Physiological Studies of The Effect of Sulfate Pulp Mill Wastes on Oysters in the York River Virginia" by Paul Galtsoff et al., US Fish and Wildlife Service, 1947, 134 pgs.).  Sulfide in the water causes oysters to stop feeding and starve causing "watery meats."  Soft shell clams also exhibit a similar impact as "water bellies."  Hydraulic clammers in Connecticut mentioned off color and off flavor quahogs being harvested in sulfide rich muds.

Some clam species are also sulfide tolerant and live in marine soils as zones when soils become sulfide rich.  This occurred in the Rhode Island hard clam fishery in the 1970's small skiff handrakers (bullrakers) harvested Mercenaria – the hard clam or quahog in very shallow waters.  Over time (1970's) inshore sets of quahogs diminished as populations of a similar looking clam that "set in amongst" the quahogs.  Soon after these "duck foot clams" or "pumpkinseed" (Pitar morrhaunua) became more of a pest as culling out these clams slowed harvest operations as these quahog littlenecks were prized for the half shell raw bar trade.  One or two duck foots in a catch (pumpkinseed) was a disaster as these clams were so bitter when consumed raw – it takes several hours to fully eliminate the sour taste (personal experience included here).  However, within 5 years 1975 to 1980 most of the quahog grounds north of Quonset Point Rhode Island now had the Pitar clam, (duck foot) and a determined effort from some Wickford bullrakers was made to wipe them "Pitar" out.  Pitar was in the areas that had muddy soils and as Pitar populations grew thicker, quahogs set less and I watched as bushels of these clams were dumped in an effort to kill them.  This also was noticed by Christine Dudley my URI director at the time located in the Wickford URI Fisheries Campus at Wickford Shipyard.  She also wanted to see if this protein food could be put to good use and not wasted (See Appendix #1).

In some areas that duck foot (Pitar) now dominated – the bottom was often then described as "mucky that smelled bad" (T. Visel personal communications with Noah Clark – Wickford Fish House early 1980s during small gear workshops held at URI Wickford Rhode Island).  What quahoggers experienced was a successional transition in the soil, an increase of plant matter and warming waters – the increase of sour bottoms acid and organic matter filled shallow marine soils.  Sulfides are formed under these soils.  Bullrakers that hit these "smelly soils" areas nearly always had poor clamming.  They in time learned to avoid them.  In the historical shellfish literature, they are often noted as "dead bottoms."


Clam Species and Habitat Change

To some of the older bullrakers seeing this change in the bottom (soil, T. Visel) was a bad sign – the smell of sulfides was also associated with "dead clams" those bottoms that stunk and contained rotting clams killed by something they just did not see but they did know the smell.  Clam bottoms left unharvested often became "foul" and covered with dead plants – both land and marine as my part of the trip bull raking was exploratory not commercial – it had been two years in the area and was at the time the perception was Pitar was consuming food that excluded the quahog.  I was invited to go bull raking to examine Pitar in the bull (clam) rakes. Disappointment set in as I had no suggestions during a trip with a local quahogger.  The industry practice was to dump the Pitar in very shallow water and kill them.  I mentioned this 1981 quahogging trip to my supervisor Christine Dudley at the URI Wickford fisheries school and she produced a Sea Grant proposal to look into the same concern – the spread of Pitar into the quahog habitats (See Appendix #1).  It is interesting to note that one of the few researchers looking into Pitar succession then was Dr. Donald Rhoads of Yale who in four years would discuss the formation of sapropels at a NOAA – EPA Long Island Sound conference in May 1985.  These ooze sulfide rich soils had at times the consistency of mayonnaise.  (D. Rhoads, EPA-NOAA Workshop -Long Island Sound – 164 pages, 1985, NOAA Estuary Of The Month Seminar Series #3).

Looking back, I noticed that the sands in the area were black, resembling the grey stains observed many times in areas covered in mud.  Some rakes produced sulfur smells – slight not intense (See IMEP #47: Climate Induced Acidification of Marine Soils, posted Feb. 6, 2015, The Blue Crab Forum™).  These are today recognized as signs of sulfate sulfide succession – as marine soils aged the habitat changed for the quahog – but helped Pitar but we have other examples to look at.  Research into Pitar morrhuana a species of no commercial value is almost nonexistent so its exact tolerance to sulfide is unknown but suspected to be greater that the quahog Mercenaria – it may have a greater "proton pump" capacity allowing it to build shell material in acid sulfide marine rich soils. 

What the Rhode Island quahog industry experienced was habitat succession – colder and cultivated soils that held a great set of quahogs (post 1938) but slowly these soils transitioned from greater organic matter inputs and in heat became more acidic at the soil interface with sea water.  This process is termed diagenesis and involves bacterial formation of metal oxides – especially iron which gives marine compost in low oxygen conditions its black color.  Sulfate reducing bacteria (SRB) found in low oxygen conditions do not break down organic matter fast enough in other words soil digenesis is incomplete and organic matter tends to build up – soils becoming muddy or in shellfish terms becoming composting soft bottoms with a sulfide smell.  These soils now take on the chemical characteristics of a marine compost. 

But the habitat questions about Pitar morrhuana leads to other species of clams those that seek out and live in sulfide rich soils.  The clam Lucina pectinata – belongs to the lucinadae family and lives in sulfides rich muds on the coast of Puerto Rico and the Caribbean Sea (Ingrid M. Montes Rodriguez et al., January 29, 2016 "Characterization And Expression Of The Lucina pectinata Oxygen And Sulfide Binding Hemoglobin Genes").

This clam contains species of bacteria that oxidizes hydrogen sulfide so it can fix carbon into nutrients, this ability allows it to live where other clam species cannot, in tropical waters under seagrass in sulfide rich muds.  In fact in tropical seagrass soils, it is a prevalent species – they need the sulfides below seagrass in which to live (Lucina Clam influence On The Biogeochemistry Of The Seagrass Thalassia testudinum sediments.  May 2007 Estuaries and Coasts 30 (3) pgs 482 – 490 Reynolds et al).  It's feeding and symbiotic bacteria help reduce sulfides below "Turtle grass" helping it live and the organic matter trapped by the seagrass helps it live.  From Reynolds et al 2007, "In seagrass sediments, Lucinids remove 2 to 16% of the total sulfide produced sulfide is a major stressor to both plants and animals in Florida.  By sediments, this removal may be important to maintaining seagrass productivity and health."

Marine Soils and Climate

The discovery this sulfide soil relationship surprised those studying sea life as clams nearly always sought out oxygen soils not sulfur ones.

The sulfur cycle is associated with early earth environments which were hot, sulfur rich and oxygen poor.  When "black smokers" first discovered in 1978 from deep sea sulfide vents it shocked many in the scientific field – pg 99 of the Hearings Before the Subcommittee on Oceanography of the Committee on Merchant Marine and Fisheries Ninety Ninth Congress First Session, The Ocean and the Future, July 15, 1985 Baltimore MD, Serial No 99-18 includes this statement (my comments, T. Visel):

"Totally new and unexpected varieties of marine life have been found associated with these hot vents (Black smokers – T. Visel).  Biologists have discovered that these communities are chemosynthetic that is, their life cycle is basically dependent upon species of bacteria which can oxidize and draw energy from sulfides which are contained in the vent waters.  These new organisms include not only bacteria, but also new varieties of clams, high five-foot long tube worms and crabs."

And further -

"These are those only known communities on the earth that do not depend upon the sun and photo synthesis for their basic source of energy.  Scientists also are amazed that these animals can survive the high temperatures and toxic hydrogen sulfide associated with the vents."     

Marine Soils and Habitat Succession

I think the first time I thought about marine soil is when I first clammed in a Rhode Island salt pond.  Here were steamers (Mya arenaria) above and below the low tide that looked much different – long smooth shells and cream colored- not the grey stained and lumpy shells of our clam bed in Madison, Connecticut.  The smooth tapered shells were in sandy mud soil, no rocks or pebbles.  I was amazed at these clams and soon came to associate them with smooth sands and some organic matter, similar to top soil/garden compost.  In Madison Connecticut our backyard top soil was mostly sand organic matter and if we dug down deep enough we would hit beach sand grey stained shells of mussels and clams.  I guess I was exposed to habitat succession at an early age.

By 1966, I was already exposed to both terrestrial composts and a garden.  Our vegetable garden was soon complemented with horse manure-the product of a Welsh pony and my participation in a Cooperative Extension Service 4-H club.  Although the pony would also be soon joined by a dozen chickens, garden composting and fish manure were already a garden soil routine.  Any fish waste went into the garden soil, which from time to time, included seaweed wrack (mostly kelp and eelgrass) although eelgrass was the mulch of choice for our strawberry plants because it did not break down quickly and it could not germinate weeds like bedding hay. This is the compost that fed bacteria needed for garden vegetable growth.  If anyone had contact with Cooperative Extension Service in the 1960's as I did, you learned about the importance of the soil pH to agriculture.  In years ahead, that would also become a daily routine for shellfishing and direct marine soil observations.

Observations -

From 1967 to 1990, I worked for or was a part of agriculture education programs that were associated with the USDA Cooperative Extension Service and a large part of that association was soil information, including what pests that lived in it and fertilizer additions to help it grow plants but above all and every spring was noted "know your soils pH."  Some may recall that even on the label of pesticides and fertilizers was a phrase that read something to the effect "If you have any questions or concerns, contact your local county Cooperative Extension Agent." 

In a decade after leaving the 4-H club of Cooperative Extension I would become a part of one in 1978.  Working for the Connecticut Cooperative Extension Service, then part of Sea Grant part-time in 1978.  In a decade, I would eventually work in some capacity for three "land grant" universities – Rhode Island, Connecticut and Massachusetts – mostly in the interest of a growing field of marine agriculture called aquaculture.  Most of my interest related to growing up watching shellfish grow in Tom's Creek and examining shellfish growing in it while living on Pent Road Madison, CT.

Almost immediately, you could see the difference between agriculture and aquaculture.  Agriculture had soil courses, soil textbooks and people who dedicated their careers to understanding of "soil science", including a federal agency called the Soil Conservation Service (now called the NRCS) and branches of the Land Grant College themselves – Plant and Soil Science departments in which you could major, but aquaculture and the study of marine soils had none of these components.  In fact, marine soil was not studied and not even called a soil, until very recently but a sediment then.  There was very little information to provide shellfishers about acid soils or soil types high in clay – a negative charge particle assemblage that often slowed clam growth we call a soil CEC.

On Cape Cod, I had copies of research conducted by David Belding, a biologist, who reported on the growth and reproduction of shellfish to George Wilton Field, who founded the first Rhode Island Marine Experiment Station on Point Judith Pond in 1897.  Commissioned after a massive fish kill in Point Judith Pond in 1896 (thought to be the result of the killing heat waves of 1895), Dr. Field did look at soil and compost and the bacteria in them. And I believe his interest and knowledge was relayed to Dr. Belding (Dr. Belding's research has been recently reprinted by my previous employer, the Cape Cod Cooperative Extension Service in 2004).  The most important aspect of Dr. Belding's research was for me that he did call clams living in a soil and included some of the basic soil science attributes, pore space by cultivation, pH, the impact of composting organics sulfides and soil stability.  (Much of that information was provided to me by John C. Hammond).

Clams living in this marine soil were predated upon by worms.  Worms were also important to terrestrial soils, and organisms that "reworked" organic compost and organic matter gave marine soils a horizon, like the topsoil on earth soils (termed today marine bioturbation).  Soils on land could become hard if compacted – and need to "open up" or cultivate and at times had low pH acidic levels.  I guess the largest factor was they were at least called soils.  In Connecticut soil compaction was seen to impact the growth of beach grass – closing pore space and in effect killing this dune grass.  (This compaction also reduces the soil capacity to hatch eggs such as piping plover they need loose soils with oxygen in cooler temperatures to prevent sulfide killing their eggs – this is supported by the fact they often seek out storm outwash fans to lay eggs).

There was just no marine soil history, no organization really to help clam "farmers" or the shellfish fishers themselves that needed successful shellfish sets to sustain capture fisheries.  The Cooperative Extension System had responded to the needs of farmers and had one-time operated demonstration farms.  But no such effort was in place in the 1970's although Cooperative Extension had an example model, demonstration farms with area farmers.

In 1966, I joined the 4-H organization – the youth in agriculture education component of the 1914 Agriculture Cooperative Extension Service, a branch of the USDA that acted as a bridge between academic agriculture research and the general public.  Cooperative Extension then had divisions of Home Economics, Agriculture, CRD, Horticulture, Poultry, Beef and the Youth 4-H.  You could not be a 4-H member without having information about soil; soil, it seemed, was the foundation of agriculture.  For 25 years, each spring I would see messages from the Cooperative Extension Service newsletters to gardeners and vegetable growers regarding soil pH.  There was no similar outreach message to shellfish growers, until the creation of "Sea Grant" the marine equivalent to Land Grant as a federal response to research and the fisheries/aquaculture community (1965).

Although the U.S. Fish and Wildlife Service did have shellfish researchers, and laboratories like those at the Milford Bureau of Commercial Fisheries Laboratory, the emphasis was on oyster hatchery science in response to diminished oyster sets in colder 1950's and 1960's.  (A largely negative NAO) No one was looking at the soil or even calling it soil for nearly half a century, (except David Belding) for most it was a sediment.  The environmental movement of the 1970s would come to embrace habitat stability and pursued regulations to protect it.  We see these regulations broadly described as sediment bottom disturbance.  In doing so this captured a habitat bias often repeated it soon became a key marine policy tenet, bottom disturbance by man that did not include nature.  Some of the largest Quahog sets in Rhode Island had, in fact, followed strong coastal storms.

That was the first problem, conservation had no really "Devil's Advocate" no one was willing to point out (at times) the positive benefits of "soil disturbance."  Although the habitats had evolved over time after countess storm (energy) events the human application of energy (attributed to dredging) was now restricted by regulations.  This public policy bias can easily be seen in the navigational dredging regulations and analysis of the literature that studied the dredging process.  Thousands of articles mention or support negative dredging environmental consequences – only a few mentions any habitat mitigation or habitat benefits, even though the habitats themselves were formed by storm energy or the lack of it.  (An added complication is research suppression the absence of reports in opposition to the no disturbance public policy and the career need to publish articles - my view, T. Visel).

It is at times an even divide – energy helps as much as hurts.  The loss aversion concept can be applied here – we tend to focus on the negative impacts of storm energy loss – windrows of clams or lobsters thrown upon a beach as I experienced viewing beaches at Madison especially Hammonasset Beach.  Here seagulls swooped down to pick up lobsters or fly high over parking lots to drop clams, it was a loss of valuable seafood.  A needless waste of sea life to the casual beach walker.  Historically the gain no longer existed as at one time coastal farmers saw immediate benefits of coastal energy.  They liked storms as it would cast valuable seaweed fertilizer up high on the beach front. (There is a depression era mural painted by William Abbott Cheever in the West Hall of the Madison CT Post Office (1940).  Artists were commissioned to paint (Fine Arts Section) Mural depicting community history in public buildings across the United States.  For Madison a shore community it was "Gathering Seaweed From The Sound," showing a horse and oxen cart hauling seaweed from the beach to be used for bedding or fertilizer).

I grew up looking at the mural and noted that the artist included garnet (red) and magnetite the grey sands that contain iron ore (this sand I used to illustrate magnetic fields to students while a Bridgeport Science Teacher) on the beach after a storm.  After viewing this deposit of iron oxide (Fe3O4) after a storm with immense wracks of kelp I knew that the artist had experienced similar storms.  (See US Treasury – The Living New Deal/Works Progress Administration WPA history) I also recall the 'red sands" after storms and hauling kelp to our vegetable garden.  Even a century ago seaweed was recognized as a valuable fertilizer – The Connecticut Agricultural Experiment Station Bulletin #194, July 1917 by E. H. Jenkins and John Phillips Street – New Haven, CT opens with this paragraph on pg. 3:

"Before commercial fertilizers were widely used, there were fine meadows and pastures in our shore towns, and abundant crops were grown.  These were produced with the aid of farm manure, chiefly made on home grown feeds, among which were the finer salt – marsh grasses (the coarser being used for litter), and also by the use of manures got from the sea – sea weeds and marine mud.  (Mostly sapropels humus mixtures, T. Visel) some "old fashioned farmers" are today using such manures with success."     

The second problem is that of perception.  Coastal settlers and fishers had long noticed peat and marine soils and the valuable salt hay they produced – pg. 191 of Geologically Considered, clearly describes habitat "success" as the tons of hay per acre.  When favorably situated (low energy period after 1878), salt marshes now could grow, in fact, expand.  Habitats could change in time and were not fixed, they could expand or contract in natural cycles.  In heat the marshes were not firm they started to sink. In our area this required horse teams to be fitted with wider snow shoe like horse shoes to keep them from sinking while cutting salt hay.  When barrier spits broke higher energy flooded marshes and reduced salt hay crops.

Truro Cape Cod or Land Marks and Sea Marks" by Shebnah Rich (1883) contains this statement (my comments, T. Visel):

"In Nauset (Cape Cod), T. Visel) from 1800 to 1840 it was estimated that flats (mud usually, T. Visel) had grown to meadow (possible habitat succession energy poor, T. Visel) capable of cutting three hundred tons of hay.  In process of time as the marsh gathers, it becomes higher and firmer."

(See Charles Beebe account of Guilford/Madison Marshes by East River dredge cut.  Salt Marshes, a Climate Change Bacterial Battlefield posted on the Blue Crab Forum Environment and Conservation Thread September 10, 2015).

The growth of salt hay required lowering the water table to allow oxygen to penetrate these peat soils but that was the extent of the marine soils knowledge in the 1800s.  To harvest salt hay required some draining and exposing peat to "drier" conditions or oxygen.  This in fact changed soil peat chemistry and its CEC cation exchange capacity. 

Energy or the lack of it could also change the chemistry of marine soils.  The movement of ions across root tissue of plants is largely determined by the soils ability to attract, hold and exchange positive ions – cations.  In order for plants and shell base builders to obtain ions for use in tissue or calcium deposition (bones and shells) they need an electrical charge – positive ions are termed "cation" and negative charged ions are noted as "anions."  This ionic exchange also occurs in fish gill tissue.  It is the electrical charges to make ion exchanges possible and why often chemical compounds have no electrical charge.  The CEC value is important to the growth of plants, and is expressed as mill equivalents per 100 grams of soil or meq/100 gram.  Soils heavy in organic matter or clay usually have a high CEC it binds (negative charge) positive ions (holds) in the top soil, sand having little binding ability have a very low CEC, ions move easily and (moved) washed by rain.  Here shallow sandy soils are ion poor – while soils high in clay or organic matter bind many positive ions – here can ions remain deep in the soil.  The CEC range is between 1 very low to 50 a high CEC range.  A high CEC means less available positive charge calcium ions.  Clams can exhibit thin or pitted shells in high CEC marine soils.

"New Sands and CEC"

The Impact of oxygen and CEC would come to be recognize in other peat soils as well – the growth of cranberry Industry for example.

I don't think that Henry Hall of Dennis Massachusetts could ever realize that his 1800's observations of "new sand" windblown on cranberries could have such far reaching applications to clam sets.  Here it is reported that in the 1800s Captain Hall observed that "new sand" applied by wind on wild cranberry vines seemed to stimulate them causing greater cranberry fruit yields.  These sands allowed oxygen bacteria room to grow and contained spaces between them (pores) to allow the movement of nutrient of ions the way plants (root tissue) obtain essential growth particles we term fertilizer.  A large part of the charged ion exchanged was nitrogen and bacterial processes with ion exchange – and the new sand provided a home for bacteria to help make these nutrients ions now "available" to plants and thus better growth, stronger vines and more cranberries.  Within a few decades it became a common practice to "sand" cranberry bogs the acid/peat negative charged peat negative soils that tended to grab available positive charge ions that plants needed also.  The more negative ions in the soil, such as organic matter the harder it is for plants to obtain the nutritious ions of Nitrogen, Phosphorus and Potassium – signified as commercial "NPK" fertilizer.  The soils ability to hold positive ions is defined as base saturation.

Today we add them in an ion form that plants can access in a fertilizer.  Bacteria are a part of this process also breaking down organic matter (manure) freeing up necessary ions found in commercial fertilizer but this process is slow and temperature dependent – cold reduces bacteria growth.  It may take a year or more for oxygen bacterial) to digest sugars in plant tissue and in the process release nutrients ions for plant growth and for farmers that then could improve yield produce.  Supplementary growth ions in commercial fertilizer could quickly increase crop yields, profit and if properly applied result in a successful farm.  Knowing the soil type and ion deficiencies therefore was key to good crops and needed information in which not to waste fertilizer.  Soils with organic matter held ions longer so plants could use them, but too much organic matter created "wet" sulfide rot and not a good growing soil.  Ask any recreational director responsible for sports fields about the need for mechanical aeration to reduce sulfate bacteria and increase oxygen bacteria to lessen sulfide build ups.  Soil aeration, pore exchange bacterial processes and ion charges are a part of agriculture we call soil science.  Modifying base saturation also occurred with liming, and modifying low pH soils, this is the level that soil binds all positive ions.

Perhaps it would be natural therefore someone who observed shore plants and clam sets with new sand to make this CEC connection (See IMEP #45, posted Feb. 5, 2015, The Blue Crab ForumTM).  Mr. John Hammond was an oyster grower and interested in agriculture as such he had seen what energy and new sand could do for clams and those plants that lived in or near water – such as cranberries and beach plums.

As Captain Henry Hall noticed, new sand increased the harvest from cranberry vines.  The new sand made it possible for oxygen bacteria to live and help the cranberry plant grow an association to "new sand" since the glaciers left.  John C. Hammond was looking at a plant and new sands, those beach plums on the beach and those inland some 150 years later.  Some beach plums seemed to bare more fruit on sand carried over existing sand dunes on Monomoy and other Cape Cod dunes beach plums buried in "new sand" by storms.  The beach plum aptly named lives on the beach in sand with very little organic matter and therefore a low CEC soil.  Mr. Hammond was blaming oak leaf litter for changing the soil limiting the plant but what really was happening was organic matter and a changing cation exchange capacity the movement of charged nutrient ions in the soil itself, called the CEC.  Oak leaf litter or powdered organics (called duff) could in time change or alter the soil CEC, increasing it over time as more organic residues built up in the soil.  Ion exchange becomes more difficult for plants.  This would reduce its capacity to produce fruit.  (He gave me a report on efforts to increase beach plum fruit production from the 1950s).  Mr. Hammond noticed that beach plum plants directly on the dune line and subject to wind brown sands produced much more fruit.

In sand the CEC is very low (few negative charged particles to grab positive ions needed for plant growth) positive ions are more available to certain plants, these plants grow quicker, can bare more fruit, and have vigor.  In organic soils – rich in clays and organic matter are higher in negative changes – they take more positive ions away from plants and have a very high "CEC," it's harder for plants to grow here and takes more fertilizer to saturate the soil negative charges called the "base saturation."  In other words, how many positive ions are needed to balance the negative charges of the soil, to make it neutral in charge and allow faster ion movement to plants.  Think of the soil grabbing and then holding key plant growth positive ions.

That is why I believe what John Hammond had linked oak leaf letter (See IMEP #45, posted Feb. 5, 2015, The Blue Crab ForumTM) to reducing beach plum plant yields, their root systems were developed to grow in sand with very low organic matter (almost none perhaps) requiring oxygen bacterial root tissue exchange more than any others, even perhaps cranberries.  Any increase in the CEC would perhaps redirect plant resources into survival and not fruit production – at least that seems apparent into today's cranberry culture where knowing the "CEC" is deemed critical.  I have seen this windblown sand aspect at the south shore Rhode Island sand dunes and the dune line at Hammonasset Beach.  Beach plums with buried branches in sand yielded much more fruit (T. Visel observations).

This is the natural aspect of new sand in the marine environment except it is not actually new but washed and redistributed sand, cleared of sulfides and excess organic matter.  Such marine cultivated soils could now "breath" have larger pore water circulation and allow carbonate ions the change to move in and out of these cultivated aquaculture soils.  That would explain the great clam sets which appear to always follow a storm event, or those flats with greasy mud that at times have almost a jelly consistency that would suffocate soils, rendering them unable to catch a set.  That would not occur in high energy areas here soils were almost constantly cultivated and therefore soils unable to succeed completely.  Low energy areas are those rich in sulfides toxic to clams.  It is in these sulfide soils Pitar morrhuana can survive why it is often found in dredge material studies.  Many of the DAMOS (dredging) studies mention the successional aspect of Pitar morrhuana living in sulfide material.  (See Seawolf Report Vol II, Report #132, 2001, Table 4-1 State III).  The ability to live in soils with high sulfide levels would place it in low energy – high organic matter soils with the potential of bacteria sulfate metabolism.  Dredging projects are usually in low energy areas – areas subject to organic matter marine composting – the formation of jelly like sapropels.  The presence or absence of Pitar might show successional processes in "dying" quahog soils.  These acid soils are found in low energy regions and may also contain a bivalve clam Macoma balthica.  Sometimes called the "Baltic clam" these species can live in high sulfide levels when other species cannot.  These small clams have the ability in the presence of oxygen to detoxify sulfide into thiosulfate by the presence of symbiotic bacteria that perform this function.  This allows Macoma to live in sulfidic soils when other clam species cannot.  In reviews of the dredging literature Macoma is often found at dredged material disposal areas.

Soil Types Also Influence Clam Growth

I don't recall when I noticed that the soft-shell clams at Seaview Beach clam bar amongst the cobblestones were bumpy with dents as compared to the beautiful long, white tapered shells of Rhode Island's salt ponds.  We didn't expect clams every year at Madison.  A "bad" winter could bury the bar under sand or a sudden storm expose seed clams to a freeze.  We could see that happen.  Some years were just better than others between the beach and salt ponds and clam growing conditions as well.  When I started to research fisheries history and to conduct fishing gear workshops, some of the oral history accounts from workshop participants sounded remarkably alike, great years and then none. 

It was during these workshops inshore fishers asked similar questions and shared their fishing/habitat knowledge.  I had few answers to these resources to soil type questions, there were just no textbooks that covered marine soils the way the terrestrial farming community was used to.  However, they didn't expect always abundance with no habitat change!  In fact, they accepted change as a cycle - great years and then very little.  The weather could change, become hotter, colder and predators as well could ruin a fishing season.  Storm could wash seafood on the beach or freeze it during winter.  The only hope was that if one species was low, something else was "high" to make up for the income loss.  Things changed – some great years followed by scarcity and then without explanation sudden abundance.  It did not seem to matter what species; all these family multi-generation accounts had similar patterns – highs and lows of coastal fish and shellfish.  William Niering hit the mark in a booklet about salt marshes when he mentioned in a Connecticut Arboretum College Bulletin #23 on page 32, Plants and Animals of the Estuary (49 pages) in 1978, this statement:

"The abundance of bay scallops varies a great deal from year to year for reasons which are not completely understood ... Old time shell fishermen say that when the clam population is large, the scallop population is small and vice versa."

It is natural that some shellfish species "reverse" even it the same habitat with a change in climate.

Marine soil chemistry changed as well and gives us a stable, non-migratory basis with shellfish perhaps which to best measure habitat succession.  They can't swim away when waters warm and soil chemistry changes.  The problem was, of course, that no one was looking at soil chemistry change because they did not consider shellfish as living in them as "soils."

While much concern and research has been expended for deep and offshore waters, very little has been spent in the small shallow embayments - those once subject to inshore fisheries and the ones that heat up and cool the fastest.  It is here that humus in oxygen forms and in the absence of oxygen can form a sulfide rich compost - iron/sapropel.  The concept of marine soils has languished for decades in the estuarine research area of the sulfur/sulfide cycle - my view, T. Visel.

The movement and cultivation of marine "aquaculture" soils has also been a neglected field of study.  When such study has happened, it has usually been a concern, often a conservation or protection issue around negative habitat "bottom disturbance" impacts.  That is part of the bottom disturbance public policy that has dominated estuarine research for decades as disturbance is always a negative habitat factor – but this belief itself contains a bias.  We may not like soil disturbance, but it is natural to have that occur along our coast.  Storms act much like forest fires; they can change or destroy existing habitats while setting a successional stage for new or different habitats.  Habitat quality and quantity is not constant and neither is temperature or storms.  In hot "quiet periods," habitats can be quite different than those "active periods" in cold.  An observation (picture) can be very different decades later.  Some plants, for example, need soil disturbance to grow or bloom.  These successional patterns are well known on land but rarely presented in marine ecosystems. 

The Danger of a Warming Planet

Acid waters and low pH marine soils has been a recent concern in warming waters subject to sulfide (sulfur cycle) formation.  Shellfish spat collection and hatcheries typically located/exist in nearshore waters subject to acid freshwaters, or acid breakdowns from bacterial oxidation or reduction.  In times of drought salt marsh peat is bathed with sulfate and a reduced freshwater table may allow increased acid discharges from peat oxidation. Heat and freshwater discharges pH can be driven very low by natural tannins in rivers, and ecologists realized the acids from draining salt marshes could kill fish in the 1960's.  All these factors could change the chemistry of shallow waters but the most often missed is soil pH, second only to the soil CEC.  It is here that sulfide and acid waters exist and so also sulfuric acid.  These acid soils kill shellfish spat in just a few seconds.

Some of the most important pH studies were conducted by Calabrese (1972) (See Appendix #4) and now brings into focus the role of bivalve shell hash in modifying soil pH and oyster growth.  It is in acid soils that the Pumkinseed clam (Pitar) thrives as a bitter tasting bivalve found in high sulfide soils.  These soils form after heat and few storms.  The Quahog responds to sandy soils free of acids such as those periods often storms.  The big sets often happened after storms in cold – such as the Rhode Island Quahog catch records show.

The pH range for normal growth is at times also climate dependent.  Storms not only would cultivate marine soils it would raise buried bivalve shell hash, the equivalent of terrestrial soil lime application.  The "sour" stagnated marine soils were how made "sweet" and shell hash now acted as a natural pH buffer for sets of clams to follow.  The testing of pH for terrestrial "agriculture" soils is taken for granted, however the study of aquaculture soils and clam succession, are long overdue.  The relationship of soil preference between the Quahog (Mercenaria) to the Pumkinseed clam (Pitar m.) would be a great first step - my view, T. Visel.


Appendix #1

The Pumpkinseed Clam of Rhode Island
A Sea Grant Proposal

PITAR MORRHUANA
URI – Rhode Island – December 1979

Titles:     Biological Assessment of the Pumpkinseed Clam, Pitar morrhuana as a Non-Utilized, Decimated Resource

Personnel:    Christine Dudley, Principal Investigator Dept. of Fisheries and Marine Technology
Sea Grant Project Summary – NOAA Form 90-2A
Institution on University of Rhode Island
Office of Sea Grant Funding Proposal – December 1979

Objectives:   1.  To assess the current status of the Pumpkinseed Clam inclusive of the biological aspects, population dynamics, geographical distribution, age-growth relationships, nutritional and organoleptic characteristics of the product, focusing on the population in the New England area.

   2.  The above-named information will be used to assess the clam's future as a marine protein source with consideration given to the
sociological stigmatism associated with this resource and a marketing analysis with defined needs, demands, and utilization.
   
3.  The applications to commercial harvesting and mariculture techniques and methodologies will be investigated.

4.  The results and conclusions of the projects will be published and serve to educate the public, enlighten the seafood industry, and aid in resource management.

Justification:

"One of the most perplexing situations in the marine protein industry is the apparent under -utilization of certain species of finish and shellfish, which have a high nutritional value and are abundant. 

An even more lamentable occurrence is the waste of resources that are caught, destroyed, and disposed of without ever being offered on the market.  A case in point is the Pumpkinseed Clam, Pitar morrhuana (Lindsley), otherwise known as the duckfoot, duckfeed or Widgeon Clam.

This species is a bivalve mollusc, approximately 1-2 inches in diameter with white chalky valves.  Its distribution ranges from Prince Edward Island to North Carolina in varying depths (Miner, 1950; Abbott 1958, Smith 1964.)  It closely resembles the juvenile (little neck) quahog (Mercenaria mercenaria) and is often found in a quahog habitat.  Summer et al (1913) conducted dredge sampling in Vineyard Sound and Buzzards Bay and determined locations of live and dead (shell) stocks.  Pratt (1953) found that the distribution patterns of the quahog and Pitar in Narragansett Bay appeared to be complementary in nature.  The quahog was most abundant in fine sediments with large particles of shells and rocks, whereas the Pumpkinseed preferred mucky, clay-mud bottom areas. 

Rhoads (1978) was of the opinion that the pumpkinseed had a high tolerance for siltation as opposed to the quahog which can barely survive more than a few centimeters of silt.

Numbers of Pumpkinseed Clam found in quahog beds in Narragansett Bay appear to constitute approximately 5% of the total population.  Since there is no market for the clam, they are being brought in by tongers (rakers) only to be dumped on shore in a pile to die.  Therefore, the stock assessment that could be quantified if the clam were only subject to natural mortality is unknown.  The traditional decimation of the stocks may be depressing recruitment and affecting the population dynamics of this species.

An important consideration from the point of view of management is the age growth relationship - how long it takes for this clam to reach maximum size.  In conversations with Dr. Donald Rhoads of the Geology Department at Yale University, it was determined that this species lends itself perfectly to his method of shell aging utilizing an acetate – peal, shell sectioning procedure.  He is currently working cooperatively with Dr. Robert Paine of the Environmental Protection Agency, Narragansett Bay Laboratory, implementing this process to age mollusk shells.  This technique facilitates counting daily growth increments and has been used successfully with several bivalve mollusc species.  It was the conjecture of Dr. Rhoads that the thin shell of Pitar might be indicative of a high growth rate which is beneficial from the point of view of commercial harvesting.  The quahog has a rather slow growth rate; from egg to market size, it takes five years in Narragansett Bay (Sisson, 1976).

The Pumpkinseed Clam is well known to a group of skiff fishermen who tong or rake quahogs.  There is a stigma attached to this species that they are poisonous or harmful to eat.  This belief has led to the needless destruction of the stocks of Pumpkinseed Clams.  Since there is no market for them, tongers bring them in only to pile them onshore to die.  Interviews with fishermen revealed the belief of a bitter taste when eaten raw.  Considering their close similarity to little neck quahogs, one can easily surmise how a confusion in species could adversely affect the little neck market.  However, these investigators have determined that when steamed, the Pumpkinseed Clams are sweet and delicious.  An additional benefit from the processing standpoint is that when steamed, the entire clam falls neatly out, with no residue left in the shell.  The Ocean Quahog (Arctica islandica) has the same bitter quality, which dissipates upon proper processing methods.  Further, the steamed product needs no additional cleaning before being consumed, unlike the soft-shell clam (steamer) (Mya arenaria) which requires the skin on the siphon to be removed.  The Pumpkinseed could be used as a cooked product alleviating pressures upon presently utilized clam species.  The present demand for clam meats is high and has outstripped the supply.  The resource availability and supply of both surf clam (Spisula solidissima) and the ocean quahog have not been able to satisfy the ability and need for industry to process more (Sugihara, 1977).

A preliminary proximate analysis performed by Professor Roland Gilbert of the Food And Nutritional Chemistry Department, the College of Resource Development at URI indicates the protein content of freeze dried material to be an excellent value compared to other commercially important clam species.

The Pumpkinseed Clam can be harvested with established techniques used in the quahog fishery including the use of tongs, bullrake, handrake, and dredges in specialized areas.

This project adheres to be objectives and goals of Sea Grant in that it is concerned with the education of the public on a little-known coastal zone species.  It addresses the management and productivity of a resource and the commercial utilization by user-groups in New England.  It also pertains to the important goal of the utilization of marine products.  In this regard, it benefits the New England area by creating a new fishery uninhibited by social stigmas, and the seafood industry from the primary producers – the fishermen on through wholesalers, retailers, and the consumer."


Appendix #2

Sediment Geochemistry Pertinent to Health of SAV
J. Kirk Cochran, Ph.D.
Professor
Marine Science Research Center, Stony Brook University

Geochemical reactions occurring in the upper – 30 cm of marine sediments have implications for the health of submerged aquatic vegetation. In particular, bacterial oxidation of organic matter leads to the presence of solutes in pore water that are phytotoxic.  Perhaps the most important of these is hydrogen sulfide produced from reduction of seawater sulfate as organic matter is oxidized. Dissolved hydrogen sulfide can also be removed from pore water as reduced iron reacts with it to form solid phase iron sulfides. In addition, SAV is adapted to handle elevated sulfide in pore water, but multiple stressors (light penetration in water column, eutrophication) may occur that hamper the plant's ability to moderate the effects of sulfide. This presentation reviews the available data on sulfur geochemistry in sediments of Long Island Sound, the Peconic Bay system and Great South Bay.


Appendix #3

The Puerto Rico Clam Lucina pectinata

"Characterization and Expression of the Lucina Pectinate Oxygen and Sulfide
Binding Hemoglobin Genes"

Ingrid M. Montes – Rodriguez et al., Jan 29, 2016

   "The clam Lucina pectinate lives in sulfide rich muds and houses intracellular symbiotic bacteria that need to be supplied with hydrogen sulfide and oxygen.  This clam possesses three hemoglobins, an iron sulfide reactive protein and (two) hemoglobin(s) which are oxygen reactive."

It is thought that this warm water clam, which inhabits tropical iron sulfide rich muds, carries a link to when oxygen was limiting in the marine environment – it can live in both sulfide-dominated and oxygen-dominated soils.  More than 100 studies are looking into how this clam can survive and thrive in high sulfide soils.


Appendix #4

High Sulfide Levels Suspected in Eelgrass Die offs in 2008
New York Cornell Study
OVERCOMING MUDDY SEDIMENTS
The Sea Grass Long Island Bog
May 21, 2008
CCE Cornell Cooperative Extension
Chris Pickerell, Eelgrass Program Manager at CCE in Southhold, New York


WEDNESDAY, MAY 21, 2008

Overcoming muddy sediments?

As I have noticed in several previous blogs, we have observed that the grass in most of our muddy bottom creeks and harbors around Long Island has disappeared.  There are many theories as to why this happened, but on the top of the list is the stress associated with growing in muddy, highly organic, anoxic (lack of oxygen) sediments.

One theory is that low light and/or high water temperatures (or some other stressor) combined with sediment anoxia kills the plants by poisoning the meristem.  This appears to have a significant impact on young seedlings.  Sulfide toxicity has been held out as the main culprit in this scenario. The problem is how can we control sulfur concentrations in the marine environment?  The answer is we probably can't since sulfur is everywhere!  One way around this may be to somehow alter the sediment in such a way that it does not go completely anoxic.  That might be achieved by lowering the amount of organic matter and/or increasing sediment texture (from silts to sands).  Since lowering organic matter is nearly impossible, we have considered changing the texture by adding thin layer of sand to the surface of the mud.  In theory, this should allow oxygen to penetrate the surface sediments and prevent sulfide build-up at the base of the shoot.

We decided to try this out at Nyack Creek in Southampton where we already have a large number of seedlings that resulted from last year's restoration work.  Over the last couple days, we set out 30 small tubes isolating individual seedlings on the bottom.  The experiment involves doing nothing to the seedling (control) or either adding 1cm or 2.5cm of sand to the surface of the sediment surrounding the seedling.  The hope is that we will see a difference in survival and growth between these three treatments in the coming weeks.

At this time, all the seedlings look great and there is no sign of stress whatsoever.  However, we observed a similar thing a few years ago when thousands of natural seedlings recruited to this site.  That year the seedlings looked great during May and early June, but by the end of June they were ALL dead.