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Author Topic: EC #21 -Sapropel Eelgrass (Peat) and The Blue Crab  (Read 283 times)
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« on: February 14, 2022, 10:15:23 AM »

EC #21  -Sapropel Eelgrass (Peat) and The Blue Crab
The Nitrogen/Bacteria Series
Peat Habitat Services for Land and Sea
October 2020
This is a delayed report
Tim Visel, The Sound School, New Haven, CT
Viewpoint of Tim Visel, no other agency or organization
Thank you The Blue Crab ForumTM for supporting these Nitrogen/
Bacteria posts
The Danger of a Warming Planet – Bacterial Composting Impacts
to Seafood

We really do not have a good understanding of habitat services for our shallow water blue crab nursery areas or the impact of heat or energy (bottom disturbance) upon them.  This appears to be especially true for submerged aquatic vegetation and sapropel sulfide buildups from a living marine compost.  Very few researchers are looking into the toxic impacts of sulfide although it is recognized as a powerful poison/toxin.  These natural substances are part of the blue crab habitat but little researched in comparison to human inputs.  Cold water, shallow ice-covered habitats also may have a substantial sulfide impact upon over wintering blue crabs, a sulfide winterkill.  Many reports have mentioned the sulfides from sulfate reducing bacteria but very few research the soil in which blue crabs live or near.   We have very few reports that measure the sulfide content of marine soils.

Researchers who looked at shallow water soils were mostly reporting on species of commercial value – oysters, clams, and even mussels as a source of protein – human food.  Their perception then was one of commerce – the cost and value of seafood.  The formation of eelgrass peat was seen to lower shellfish production.  Those reports can be found in the historical fisheries literature.

For example, J.C. Medcof of the Fisheries Research Board of Canada writes in “Oyster Farming in The Maritimes” (1961):

“Eelgrass has inconspicuous, green flowers and reproduces by seeds, but it spreads mostly by extending its long strong, underground roots – stocks, which form a network in the soil.”

And –

“In some places, oystermen complain about eelgrass because it interferes with fishing.  Dense stands reduce water circulation.  Fatness of the meats may also be affected.  Sometimes in autumn broken off eelgrass leaves are blown into shallow water and cover beds of oysters and smother them.”

David Belding on Cape Cod was very direct about the impact of eelgrass upon the softshell clam.  He writes:

“Eelgrass as we have seen is fatal to a good clam bed.  Many productive beds would be quickly spoiled by eelgrass if it were not for constant digging.  The grass raises the surface of the bed above the normal level by bringing in silt, which smothers the clams.  The reclamation of such flats can be accomplished by destroying the grass and allowing the water to carry away the accumulated muddy deposits.  At Newburyport, an eelgrass flat with a surface layer of soft mud was converted into a productive hard flat by digging.  A strong current removed the loosened material, and a new flat about one foot lower than the original was formed.   A coating of algae often helps to protect the flat from too much shifting and the mud surface furnishes abundant food forms.  Eelgrass helps to hold the mud firmly but as it also catches silt, it forms a layer of soft mud, which is apt to smother the small clams.  It occasionally happens that parts of a flat, which seem similar in every respect exhibit extreme differences in the way they harbor or repel that clam set.  It is almost as though an invisible line had been drawn beyond which clams did not grow, Hydrogen sulfide and other organic compounds in the soil may account in part for this condition.” 

Irving (1922) comments on the impact to mussels in his Bulletin of the Bureau of Fisheries, The Sea Mussel Mytilus edulis, on pg. 219, which includes the following:

“Eelgrass, Zostera marina, is one of the most destructive weeds which grows in profusion on the sheltered beds.  It not only intercepts the currents which bear the food supply of the mollusk but causes very often such a heavy deposition of silt that the mussels are smothered or even completely buried beneath it.  Their decomposing bodies then form the richest kind of fertilizer on which the eelgrass thrives.”

These viewpoints would not get much attention today as the habitat succession of eelgrass peat would favor species desiring reef or cover from predators, not so much shellfish.  On Cape Cod when eelgrass thinned or was ripped out by storms, other species thrived including the bay scallop.  In the shellfish literature of the 1930’s and 1940’s, eelgrass was associated with small eyes (meats) bay scallops.  The decline dieoff of eelgrass was devastating to Brant – a primary forage virtually disappeared and large populations of Brant starved or turned to sea lettuce.

Marine Compost, Scallop Vegetation and Forage for Waterfowl – All Eelgrass Observations

The initial studies of eelgrass as a forage important to duck and as a bay scallop setting surface often included detailed observations.  Later, the life cycle of eelgrass was looked to support public policies associated with numerous claims and narratives of human negative impacts.  These impacts range a broad spectrum of eelgrass associated seafood declines namely nitrogen enrichment, coastal development, recreation (fishing) and sea level rise.  Eelgrass was to assume a heavy burden in many areas of seafood decline as well.  At one time, articles mentioned that perhaps eelgrass could save the planet.

This bias can also be seen in the absence of natural eelgrass cycles – nature itself destroys acres of eelgrass during storms while at the same time preparing marine soils for new eelgrass seed pods.  Storms also act to move seed pods as a dispersal function in recently “cultivated soils.”  In cold, eelgrass acts as a reef and structure habitat – very positive to fish and crabs.  But in heat, these habitat services turn negative as sulfides build under eelgrass, which “bleeds” sulfide into the water column.   Eelgrass is a vegetative cover for composting organics.  It is a grass that can grow in nutrient-poor sand, taking nutrients from the water.  As composting proceeds, it depends on its roots.  In periods of heat, the compost that eelgrass holds becomes sulfide-rich, weakening and then killing it (See Sulfide Intrusion and Detoxification in the Seagrass Zostera marina, Hasler-Sheetal & Homer, 2015).

This is how we have hundreds of eelgrass reports that mention the same positive habitat services but forgot to include negative habitat services in heat or the sulfur cycle that exists below the eelgrass peat surface.  A growing connection to the NAO for explanations of the cycles of eelgrass is more plausible.  We need to look beyond the short-term habitat services of eelgrass, which at times can be positive and other times negative.  This is especially important as a warming climate will enhance sulfide formation.  Eelgrass cannot cure all of our coastal pollution ills.  Nor should we expect it to.  Warm water and high organic soils can kill it – this has happened before.
In the 1940’s, the US Fish and Wildlife Service Biological Survey to restore site-specific eelgrass stands (to help Brant), even transplanted non-native eelgrass strains.  (Martin et al., USDA Technical Report 1939 Food Of Game Ducks In The United States).  It is also possible that we have several non-native strains of eelgrass carried aboard sailing ships as packing materials for shellfish or to keep green crabs alive for food purposes (See The Search for Megalops #3, August 4, 2016).  Our strains presently in New England might not even all be native to our shores.  We might have centered on public policy initiatives around a plant strain that could be, at times, termed invasive in attempts to form a monoculture here in New England.

Nitrogen and Impacts to Habitat Quality

The absence of including bacterial biochemical composting processes in the calculation of nitrogen impacts habitat quality for the blue crab is flawed because ammonia is toxic to most fish and shellfish.  The influence of bacteria to nitrogen inputs especially ammonia is not mentioned or “glossed over“ as “biological processes” but rarely clearly defined.  The presence of ammonia (pH 13) is now suspected of protecting buried HAB cysts deep in sapropel deposits for centuries.  The formation of eelgrass peat in high heat is damaging to shellfish as it holds organic matter for sulfate-reducing bacteria.

This has allowed a huge bias to enter many estuarine habitat reports – oxygen solubility in very warm (hot) seawater.  Such exclusion of bacterial generation of nitrogen compounds – cold nitrate and heat ammonia, introduces a climate cycle nitrogen bias, in periods of heat it is natural for bays and coves to show more ammonia in them (from bacterial pathways) and in cold it is also natural for the same areas to show more nitrate – also from bacterial pathways.  In cold inlets tend to reopen, (colder waters is denser and therefore its erosion capacity is greater) flushing times decrease as more colder seawater can enter and influence nitrate production – in heat inlets tend to heal (this is one of the most mentioned habitat impacts of black water in the historical herring (alewife) fisheries literature as “stagnation”).  Nitrogen (ammonia) is retained in them.  No matter how or what climate pattern exists, temperature and energy can alter bacterial nitrogen generation.

Nitrogen Levels Need To Be Indexed To Temperature

This nitrogen change would need to be indexed with temperature but it often is not.  In fact in many estuarine studies, the bacterial generation of ammonia is from sapropel (marine composting) is not mentioned at all?  This is hard to understand as the agriculture community has long recognized organic compost as a bacterial source of nitrogen compounds – also in cold nitrate and in heat ammonia.  It is the hot times of low wind and tidal energy that frequently proceeds the blue crab jubilees – but these critical factors temperature and energy and the role of bacterial source ammonia is frequently left out of the blue crab jubilee discussion. 

In low oxygen the bacterial pathways switch, and bacterial strains access sulfate for oxygen, producing sulfides (the rotten egg smell) and purge ammonia – fuel for the explosive growths of Harmful Algal Blooms (HAB’s) or suffocating growths of macro algae such as sea lettuce.  But these bacterial strains need organic matter and after heavy tropical storms such as Agnes in 1972 deposited organic matter in the shallows, food for sulfate reducing bacteria.  The presence of sulfide can cause benthic species to flee softshell clams will “pop out” as other benthic species flee these waters or as the blue crab walk out.  Fish and shellfish that are killed contribute to the low oxygen event and if long enough help create black water, a sulfide killing zone (See Marine Fisheries Review Paper 1356, Steimle & Sindermann, 1978, “Review of Oxygen Depletion and Associated Mass Mortalities of Shellfish in the Middle Atlantic Bight in 1976”).

This event is called hysteresis that is the final result lags behind what first occurred – what is observed is the Jubilee what is not often included is the climate/bacterial processes that proceeded it.  Under water and beyond the scope of many studies the role of sulfide remains poorly understood, even today.  This aspect is compounded by a tendency to assign jubilee factors to human caused events, or inputs ignoring any possible role in biological processes or eliminate bacteria for contributing factors.  This is quite evident with many nitrogen studies – the emphasis upon human nitrogen inputs but ignoring bacterial nitrogen processes or watershed water sources, which at times may overwhelm human inputs. (The bacterial generation of nitrogen from plant tissue is not “new” nitrogen so it was not included in many nitrogen studies - T. Visel).  Human-generated nitrogen can be a negative aspect to habitat quality but needs to have a level of degree assigned to it – my view.

That was a case several years ago in Old Saybrook, Connecticut, a shore community that had about 3,000 residents living within 1,000 feet of the coast or coastal streams (See IMEP #41 Addendum, Dec. 23, 2014, The Blue Crab Forum™).  Assuming no attenuation (natural removal or uptake of nitrogen by soil or plants or loss to the atmosphere which is usually 50 percent) all the human generated nitrogen delivered directly to water courses at 8 lbs. per person per year.  These residents, it was estimated, generated 24,000 lbs. of nitrogen per year.  But the Connecticut River, which empties at the Old Saybrook shore carries 78,000 lbs of nitrogen per day.  Even if these residents moved from the coast the reduction of nitrogen likely would not be noticed.

People input 8 lbs/year – or 3,000 x 8 lbs nitrogen per person/year, no attenuation contributes nitrogen at a level of 24,000 lbs./year while the CT River mouth is located between Old Saybrook and Old Lyme is estimated at 78,000 lbs. per day or 3,250 lbs/hour of nitrogen to coastal waters Old Saybrook, from the above calculations, (my calculations) equals about 8 hours of input per year.

Source – An Evaluating of Potential Nitrogen Load Reducing to Long Island Sound from the Connecticut River Basin – Barry M. Evans, The Pennsylvania State University
78,658 lbs. of nitrogen/day – pg. 6

Can The Salt Marshes Be Saved?

This section attempts to describe some of the cyclic habitat changes in salt marshes as they also respond to heat – associated with that description is a public policy component that so dominated the late 1970s into the early 1980’s – protecting and saving “the marshes from development/destruction.”  Concerns were raised about the strong influence upon science as a bias (also termed agenda-based science today) and two researchers in the 1980s Scott Nixon of the University of Rhode Island and John M. Teal of the Woods Hole Oceanographic Institution brought the conflict to light – concerning the energy flows of organic matter – in or out of salt marshes.  It created much controversy in the marine field for decades with “dueling” points of view about the concept of “outwelling.”  (Two publications mentioned here are referenced below).  Much of this same cause and effect bias would later be repeated in eelgrass habitat studies both as a way to include the Clean Water Act in nitrogen reduction and the promotion of anti-bottom disturbance of coastal bay bottoms by limiting dredging policy.  The bias in recent eelgrass research is that it mentions positive environmental services in periods of initial appearance (usually with cold) yet “forgets” the negative environmental services of eelgrass habitat succession (usually with heat).  This is even more complicated with sea level rise and rising atmospheric temperatures.

The same occurred with salt marshes studies – in fact the pattern repeated in later eelgrass appears first in salt marsh studies – highlight the positive and forget the negative. That is why it is difficult to explain that in high heat marshes and eelgrass will turn against the seafood we like and in some cases against us.  Much of the current eelgrass literature is almost no value in long-term habitat studies.  Not only were they subject to a public policy bias (also termed the funding effect) but conducted over very short time periods that largely excluded any negative impacts.  As for the salt marsh studies of the 1980’s both Nixon and Teal made us aware of the huge bias potential – around the value of salt marshes.  Teal repeats Nixon’s 1980 warning in 1986 in his preface to The Ecology of Regularly Flooded Salt Marshes of New England – A Community Profile – USFWS:
“Note his comment on the inadvisability of trading “our credibility for political advantage.”  This has certainly happened in relation to salt marshes – Teal comments and later Teal issues his own warning in bold print (which is rarely used in literature only to raise the level of concern) – “Scientists should make the best information available – they should remain skeptical about their conclusion … They should not go to the most conservation extreme and never be willing to give an opinion about the wisdom of some proposed action.”  (The Ecology of Regularly Flooded Salt Marshes of New England, A Community Profile John M. Teal, US Fish and Wildlife Service Biological Report 85, (7.4), June 1986) 

Teal, however, does provide a glimpse of what lies ahead for salt marshes subject to high heat and rising sea level.  (Although rising sea level has been a constant feature of the New England shoreline, it did not become subject to public policy debates until the mid-1990’s.).  Page 9 of The Ecology of Regularly Flooded Salt Marshes of New England (Teal, 1986) contains the following:

“Conditions in the marsh sediments are greatly influenced by the abundance of sulfate in seawater.  Under anoxic conditions, there are some bacteria that use sulfate as an electron acceptor, decompose organic matter, and produce sulfide.  The resulting sulfide is primarily responsible for the degree of reduction in marsh sediments.  Sulfide is highly toxic to most organisms, so those that inhabit marsh sediments must either deal with it or avoid contact with it.  Metals, especially iron, are also abundant in marsh sediments, and much of the sulfide produced is bound up as metal sulfides” (King 1983; Howarth and Giblin 1983).

Nixon (1982) would author “The Ecology of the New England High Salt Marshes – A Community Profile” and discussed peat in the presence of oxygen.  On page 45, Nixon details this difference as “The high marsh is not usually considered an important source of organic or nutrient exchange with the tidal waters.”  When comparing these two publications Nixon and Teal you see a divide in the nitrogen cycle – one dominated by the short or ready nitrogen cycle is oxygenated environments (termed the high marsh) found in the 1982 Nixon paper and the longer nitrogen cycle highlighted by Teal – in the lower marsh, which at times included the significant “sulfate reduction pathway” (pg, 35, Teal).  Teal (1986) also describes what would happen in heat (oxygen inverse solubility low) as oxygen became limited – the rise of anoxic conditions  (The EPA Estuary studies were created by Congress and commenced during this same period.  I served on the Science and Technical Advisory Committee of the Long Island Sound Study in 1988).

Pg. 34 Teal (1986):

“Anoxic processes common to marine systems use nitrate (denitrification) and sulfate (sulfate reduction) as electron acceptors in place of oxygen.  These anoxic processes yield less energy to the microbes that perform them than oxygen consuming processes due to aerobic microbes.  There is slightly less energy produced in the case of denitrification but substantially less in the case of sulfate reduction.  A vertical cross section of marsh sediments might reveal the oxygen-using organisms at the surface, denitrifiers below them, and finally the sulfate reducers in deeper layers.  As long as oxygen is present, organisms that can use oxygen outcompete the others simply because they can obtain energy from organic matter more efficiently and thus grow faster.  At the depth where all of the oxygen has been used, the denitrifiers are most efficient, and at the depth where the nitrate is also exhausted, the sulfate reducers come into their own.”

What I term “coming into their own” is winning the bacterial habitat war with all its deadly consequences – one of my previous posts mentioned this as “not liking the score but still being forced to watch the game” sulfate reduction and sea level rise will cause salt marshes to collapse digested by bacteria.  Many times, bacteria release of carbon feeds marine and estuarine subtidal plants, food for ducks.  The ducks’ waste would then fertilize the water and plants.  Over time, organic matter would form peat and plant growth close the open water.  In the 1950’s and 1960’s, duck habitat programs were developed to excavate peat for open water that did not freeze in winter.  If this cold shallow water froze completely, ducks moved to other areas.

But programs to dig out peat for open water, producing an increase of forage grasses, was a slow habitat process.  While ducks would congregate in or near them (open water), they held at first little forage grass.  Many areas were just too deep and the shallow sills and banks that submerged grasses needed – to attain sunlight (such as a primary forage grass eelgrass for Brant) did not exist.  Grass needed sunlight – these peat and constructed ponds would need habitat succession, the accumulation of build up sapropel (compost) that when exposed to oxygen turned brown and could support plants.  The success of plant forage was dependent on oxygen and this was a double-edge sword, very cold and marshes froze over, duck hunting declined.  In warm waters, oxygen became limiting and fish kills increased if a strong thermocline developed.  A thick growth of forage grass – good for ducks eventually filled areas with organic matter and supported bacterial processes that “robbed” water of oxygen causing a rise in toxic sulfides or black water in extreme heat (See the Blackwater National Wildlife Refuge in Maryland).  The ducks themselves helped this process by their own manure, recycling plant tissue into manure to sustain photosynthesis of forage grasses.  In the 1930 to 1970 period was relatively stable and these manmade habitats helped duck populations they did so only when it was cool, and temperature (climate) moderated as temperature warmed (heat) an increase in aquatic plants (once desired) now became a detriment and pg 38 of a 1993 CT Dept of Environmental Protection Fisheries Division DEP Bulletin #19 – small ponds in Connecticut A Guide to Fish Management (Murphy and Mysling) pg. 38 has this statement:

“Aquatic vegetation in amounts of up to 40% areas coverage is optimum for small ponds inhabited by warm water and cold water fish (freshwater – T. Visel).  When aquatic plants exceed that percentage they may interfere with intended use of pond.  Only when plants reach nuisance proportions should they be considered weeds.”

On page 50-51 - Dredging (deepening) has this statement on the control of aquatic plants when they became a nuisance:

“This method involves the physical removal of accumulated bottom sediments.  The process increases littoral zone and open water depths to levels at which bottom growing plants will not receive enough light to survive.”   Dredging is initially very costly, however, the results have long term benefits.”

The leaf fall is enough nitrogen (termed hard nitrogen) to over enrich ponds.  This “locked up” nitrogen also includes blossoms, seeds, fruit (acorns) twigs and branches.  As water warmed hard nitrogen and added human nitrogen to ponds to stimulate plant growth now in heat was a pollutant.  Hot water contains less oxygen and bacterial sulfate reduction soon produced a toxic by product – sulfides.  A strong summer thermocline can seal surface oxygen from deeper waters, making the chance of a fish kill even greater.  This is when “black water” with sulfides can form.

These bacterial conditions can result in fish kills and the creation of organic fluids from bacterial reduction – waters now become cloudy as algae grow and reduce photosynthesis - This process is accelerating by heat – termed eutrophication.  As temperatures rose in the 1970’s warm water became cloudy and in cold clear water sunlight benefited those grasses with roots as warm algal filled water did not, the cloudiness prevented sunlight from reaching submerged grasses except these that floated and as pond vegetation changed a habitat succession occurred.  These plants died.

It is at this time that habitats were compared to cooler temperatures, and pond associations were directed to reduce – nitrogen entering the water but organic matter (hard nitrogen) from leaves, twigs, bark, cut grass was also part of the habitat process in heat – under these conditions left few alternatives to dredging – removing the plant compost could break this bacteria, nitrogen cycle.  In deeper poorly flushed lakes or those in which overturn was delayed, there gave rise to bottom sulfide waters, often black, which if changed quickly enough in the fall created sulfide fish kills.  Ponds and lakes surrounded by oak forests are susceptible to brown water or tannin tea – a natural acid from the bacterial decay of oak leaves (pg. 67) and may require pH treatment.  These can be seen after heavy rains as the water appears to be brown, or chocolate.

“Ponds constructed in wetland areas or in oak forested” watersheds may have waters stained a brown or tea color by tannic acids.  Pg. 67, Small Ponds In Connecticut A Guide for Fish Management, DEP bulletin 1993 and further,

“Such ponds may be treated with lime to raise pH and improve water transparency.  Apply at a rate of 500 to 1,000 pounds per acre.  Lime treatments need to be repeated periodically.  Without treatment, these ponds will have very poor light penetration, thus, photosynthesis and oxygen production will be severely reduced below 3 feet in depth.”

In heat, the presence of tannins increases – the heat reduces the ability of oxygen requiring bacteria to break down leaves – they tend to accumulate in a habitat successional process – as the water clouds it blocks sunlight to submerged grasses in estuaries as well as fresh water ponds.  Shallow waters are more influenced by wind or waves and this tends to support water algae strains then rooted plants.  In times of heat this had nitrogen helping habitat succession naturally and dredging the removal of plant compost is an energy (input) – the natural events of plant growth and settlement most ponds will eventually become bogs and then marshes – fresh or salt.

Temperature Could Slow or Speed the Process – the NAO – North Atlantic Oscillation

Salt marshes over time were linked to diminished fisheries and human coastal development.  This came out of decades of human disease and the filling and ditching of salt marshes (See Mosquito Bulletin titled “The Mosquito Plague of the Connecticut Coast Region and How To Control It,” Connecticut Agriculture Experiment Station, July, 1912).  This habitat history is frequently missing in many recent salt marsh studies, even those that claim to be historical. (At one time, Connecticut promoted the filling of salt marshes to stem Malaria disease outbreaks.)

As the human explanation intensified for any change in fisheries, a self-fulfilling type of shellfish climate cause unified only the human impact message.  In time, the natural resources fluctuations were almost always the result of human actions.  Much of that involved resource overharvesting (overfishing) pollution and coastal development – filling and dredging.  As the message unified to the public any other possible explanations (other than for example pollution or overfishing) for resource declines disrupted the message and created a sharp division in observations and historical references shaking current beliefs and policies.  History has a way of doing this and why perhaps historians have had difficult times detailing what appears to be true actually is not.  Because historians frequently seek out broader views and over much longer periods of time (history itself), their providing a “mixed message” is frequently rejected or protested.  A unified message is powerful as it can become a norm and rallying position for public policy efforts, “Saving The Salt Marshes” is an example of 50 years of beliefs and values being challenged by climate warming.  In heat salt marshes cause natural nitrogen pollution the source of black water fish kills, disease and human health hazards.  That was not included in the salt marsh protection policies during the much cooler 1960’s and 1970’s but in the 1890’s Connecticut declared salt marshes a public nuisance – (see Bulletin Series Yale School of Forestry and Environmental Studies #100 David G. Casagrande, volume editor, “The Full Circle:  A Historical Context For Urban Salt Marsh Restoration”) and instituted a program of draining and ditching to eliminate mosquito habitat and the threat of mosquito disease then Malaria.  That aspect was rarely discussed in public policy efforts to preserve them – anyone mentioning a different value and habitat history in heat would have been on a path that very few followed.

Pure Oysters and Clean Milk – Farmers and Fishers
Fight Bacteria Contamination in the Great Heat Waves of the 1890s

This report started in March 2014 and was a capstone proposal for our students looking into HACCP and bacterial contamination of milk and oysters.

Although it does not specifically look at fish and shellfish it does examine a common foe – one that is increasingly gaining importance in habitat quality – bacteria and how climate patterns can impact habitats and habitat capacity for seafood we “value.”  While many programs have targeted nitrogen removal or reducing contaminants, worthy public policy issues, including the study of marine bacteria, have languished for decades.  In high heat, however, bacteria becomes very important – as most of fish and shellfish species need shallow areas for their early life stages. This is where bacteria have such an important often unseen role in seafood habitat quality and that includes nitrogen.

Over the past ten years, a tremendous amount of habitat change has occurred in New England.  After many years of heat, warm winters and few storms – the cold (at least cooler) climate has returned – at the same time nature with these storms has turned natures compost pile – marine sapropel and revealed the extent of these bacterial populations.  This appears in publications as the rise in Vibrio species happened a decade ago.  Much of the habitat change can now be attributed to sulfur reducing and ammonia oxidizing bacteria, during hot and cold periods bacteria change in response to heat or cold.  The examination of “hot” and “cold” periods offers a unique opportunity to glimpse into these bacteria populations – how they can impact us and the seafood (foods) we consume.  These bacteria need sulfate, not elemental oxygen, to live.  Sulfate dissolved in seawater is an oxygen source that is “non-limiting” in heat and why a warming planet is a threat to oxygen life forms.  A warming planet will end the cool cycles in which cold water species “recover” such as the bay scallop.

A close look at the sulfur cycle and sulfur reducing bacteria is needed to fully explain the dangers of heat, my view.

The current environmental policy supporting nonbottom disturbance is exactly what conditions these sulfur reducing bacteria require to thrive, sapropel deposits that have wax paraffin residues (much from decomposing oak leaf residues) seals off oxygen from surface waters – allowing sulfur reducing bacteria to multiply with all their negative impacts in this marine compost.  Most terrestrial gardeners know the benefits of “turning” over a terrestrial compost pile to add oxygen to aid the “good” bacteria (especially in hot weather) the ones that reduce organic matter into a useable soil/nourishing constituent but that knowledge did not transcend into the marine environment.  Although shellfishers for centuries have noted the positive benefits of marine soil cultivation “working the bottom” similar to compost turning but that runs counter to most of the coastal policy today which seeks to minimize disturbance in any way.  A rich heavy layer of organic matter provides a culture media for sulfur bacteria – that slowly consume organic matter in the presence of sulfate releasing hydrogen sulfide into the water.  The same situation can occur in terrestrial composts – termed smelly as ammonia/sulfide smells eliminate from them – The same nitrogen release occurs in the marine environment.  In this case the good composting bacteria lose out to the sulfur bacteria with all of their deadly and disease-causing impacts.  Warm (hot) sea water with little bottom disturbance is what enables sulfur bacteria to become so deadly to larval forms and even fish and shellfish eggs – they in fact rob the seafood cradle.

While these bacteria crave quiet stable conditions, nature can upset them by natural turning of marine composts by storms – the currents and waves are natures compost shovels and like chemical processes on land there is oxygen tension imbalance (deficits) immediately after such overturn – followed by a acidic “wash” which is so devastating in warm weather.  This process is thought to re-open cysts or spores and helps to form toxic algal blooms.  This event may even lead to a better understanding of MSX oyster disease.

Increases of high organic deposition and no disturbance in heat nature helps sulfur win – and when that happens, we lose the seafood upon which we value. 

The Great Heat and the Rise of Bacteria A Century Ago

One of the features it reviewed was the “Hot Term” or what I call The Great Heat the 1880 to 1920 period, which saw progressively hot summers and Long Island Sound was the heat sink for moderating winters.  It took a series of very hot summers to warm Long Island Sound until its peak in 1898.  The impacts of smaller bodies of water were more noticeable, New England had a ice failure – in 1899 lakes and ponds just did not lose the “heat” fast enough for ice to form – even if it was “cold enough.”  An ice panic ensued and “Ice famines” and (NPR has a great segment titled “The Heat Wave of 1898 and The Rise of Roosevelt, August 11, 2000) as prices soared.  When ice speculation (market manipulation to obtain the highest prices) withheld ice supplies in the New York City area Theodore Roosevelt just went in and took it – ice was the war material he needed to fight death – and control bacteria in food.  He made certain that New York City’s poorest residents got a fair share of ice, an act they did not forget – nor should we.  It was a battle against bacteria as well as temperature – the two are very much a combined concern.

The Connecticut Dairy industry had also grappled with bacterial contamination in this same “hot term” lacking the modern refrigeration facilities of today milk often became contaminated and linked to disease outbreaks especially among children bottle fed milk.  Thousands of children died.  The issue of pollution and waste would have farmers blame cities.  City residents (mostly poor) struggled against a formidable foe – bacteria as coastal fishers watched some of its fisheries die off.  In the end city, residents, farmers and fishers all faced a common enemy – bacteria.

Bacteria does very well in warm water, in fact bacteria thrives in it, during this very warm period (1880 to 1920) hottest between 1890 to 1910 fishers, farmers and city residents suffered greatly from the heat and the bacteria that grew in it.  It is this period that cities closed public wells, contaminated and the vector of diseases, fecal sewage canals closed productive shellfish beds and milk contaminated with bacteria killed hundreds of children – some of the highest death counts per capita occurred here in the city of New Haven.  But the source of Vibrio cholerae and other bacteria outbreaks usually occur in warmer temperatures – in water or contaminated milk.

The 1890 great heat waves killed thousands in New York and Boston, there was nothing great about the heat for city residents.  Those who could rushed to the shore for the coolness of shore breezes – the heat then would cause an almost constant south westerly shore breeze – creating “shore communities almost overnight” that soon shared them. 

Long Island Sound then was a “cooling center” of enormous magnitude, but even the cool Long Island Sound became hot in time and summer communities moved north – even into coastal Maine.  In historical bulletins of shore coastal communities, the “hot term” is most frequently mentioned. 

To be respectful shore cottages were bound by cedar post fences not to rob your neighbor of a shore, breeze.  Those remaining in cities during this heat now fought disease and bacteria with what they could, fans (if available) ice and clean water.  In this heat bacteria had a field day, contaminating food such as milk and oysters (and shellfish in general) even water itself became deadly.  It was the water contamination of city wells that created the framework for the public health service.  It is this period that “water rights” become important as cities looked for clean water from New England’s cooler streams – many from inland areas.  Although formal declaration would ever be issued but society soon waged war against its most deadly enemy, bacteria.  (It would also put an end to “the germ theory” debates that for decades blamed cities for pollution disease by “foul airs” – which was greatly magnified by the heat).

In response “City Water” water that arrived in “mains” under the ground delivered clean portable water, much from aqueducts quickly constructed from reservoirs (Quabbin Reservoir in Central Mass took entire towns).  The typhoid and cholera outbreaks in the later teens had brought the oyster industry to its knees, and large areas near the coast were closed to direct shellfish harvests. Dairy interests (which had long opposed pasteurization) finally accepted the process – and milk fatalities dropped – sometimes dramatically.  By 1903, commercial ice facilities soon put an end to the terror of the “ice famines” and later refrigeration replaced the household iceboxes needed to prevent bacterial food spoilage.     

Cities recognized the need to change also depriving bacteria of ready nutrient sources. Bedpans could be combined with toilet closet waste and merely dumped in surface street sewers – a new “sanitary sewer” basically the same principle but now underground as collecting and diversion of human waste away from population centers.  We had in a way declared war on bacteria – and its battleground battlefield advantage was heat and sewage organic matter.  In hot water bacteria thrived and cool clean water from “springs” became popular – in this recent “hot term” bottled water would again soar.  In the 1970’s – 1980’s many remaining natural “springs” in Connecticut would be posted as contaminated I can recall in the 1960’s people would still bring glass jugs to roadside springs to fill until these also became contaminated with bacteria and bird vectored parasites. 

Lobsters died in the 1890’s called black tail (Jeff Wilcox, personal communication to Tim Visel, 1980’s) and rotted in heat in railroad cars.  Bay scallops, at one time (1870’s), disappeared halfway into this forty-year period.  Greenwich. CT caught thousands of bushels of bay scallops in 1818 by 1898 they were gone.  Brook trout were declared almost extinct.  It was also the time of increased shellfish closures from cholera, a Vibrio bacteria.

The Rise of Bacteria in Coastal Waters

It was in the middle 1970’s I would also meet with Leo Bonoff Town of Madison – town clerk.  Mr. Bonoff was the Town Clerk for many years, it seemed for the entire time I was in Madison, and helped me research many oyster records at the time in the town vault.  I will always appreciate the many hours he would spend sharing his insights and changes in Madison.  (He also had operated the local movie theater). If you wanted to know something, I just went to Mr. Bonoff, and he would drop everything and help you out.  It seemed to me that the town clerks then held most of the institutional knowledge of small towns then, at least it seemed that way in Madison. 

By 1975, I, myself, had squared off against bacteria, myself in a very small way.  Our favorite shellfishing creek Tom’s Creek had to be closed to direct shellfish harvesting – from high bacteria counts.  I had the reports from the CT Health Dept and had provided the skiff for a sanitary survey with Jim Citak – high counts were carrying in during heavy rains and some grey water discharges located.  The brook however from Liberty Street and RT 1 held the highest counts.  What was the source of this bacteria?  The only other records of bacteria tests conducted at the time were tests of swimming beaches.  So, as with many other questions, I went to see Leo Bonoff, our town clerk.

After a few minutes of searching, he found the beach reports for The Surf Club – a Madison town beach started in the 1950’s – tests around the 4th of July and bacteria counts were in the single digits, not like the “thousands” at the start of Tom’s Creek.  I recalled that I said I saw no difference in the creek – he responded something as to “you can’t” and he recalled that many wells had become contaminated along the shore – requiring “city water.”  At first no one suspected the water but in time water was brought to the shore – wells were to shallow (many hand dug) and bacteria got into them.  Mr. Bonoff also entered in his opinion – to him, the winters were warmer, summers hot and was selling a lot more dog tags (as we had).  He related that was part of Madison’s history – fishing and farming had become hotels and summer cottages – built during a time people came to the coast for cool breezes (our home on Pent Road was once – a summer cottage for members of Altobello family from Meriden).  That is why so many cottages were built – people came to the shore not so much to fish – but for relief from interior heat.  To him the Sound had calmed down – In the 1950’s and 1960’s the Madison Flood and Erosion Control Committee meetings were standing room only, so packed you couldn’t sit, (many hurricanes) but now “barely made quorum.”  To Mr. Bonoff, the Sound had turned quiet and it was getting warmer as it had before.  (In the later 1980’s I was to research the history of the Flood and Erosion Control acts – and it was all of these (1960’s) as Mr. Bonoff mentioned hurricane after hurricane claimed more of Madison’s beaches soon and groins and jetties now replaced damaged sea walls, such as the jetties at Tom’s Creek).  People were walking their dogs and, well it rained so he was not surprised about the higher bacteria counts – he was selling more and more dog tags every year.  Madison’s summer cottages were being rebuilt and converted and their seemed to be a lot more dogs.  I always appreciated his insight observations and direct responses – short, direct and absolutely on the mark.

Mr. Bonoff would never see how hot it was going to get into the late 1990’s a return of a second “hot term” and one that resembled the 1890’s – almost exactly.  In this heat and warmer water bacteria had staged a comeback closing thousands of acres of shellfish ground infecting lobsters and winter flounder with shell and flesh wasting bacteria (the Vibrios) – and long vanquished sulfur reducing bacteria would change tidal flats and even some salt marshes into natures killing fields.  It was the heat and bacteria that created so much habitat change, not so much “us” global warming would mean that bacteria will become more of a foe to coastal fish and shellfish habitats and cool water a more important resource.

The battle of bacteria will most likely be the last fought in a global warming war.  The recent two “hot terms” only just skirmishes pointing to the importance of reviewing past tactics for storms and heat as we face a warmer future.  When it comes to bacteria, we can never underestimate its capacity to change how we live – my view.

I respond to all emails at [email protected]   

Public Policy and Agenda Science

One of the many questions I had soon after the dramatic rise and crash of lobster post 1998 was it resembled precisely the rise and fall of lobsters here in 1898.  No one mentioned this historical lobster cycle?  Looking back most of the research grant funds to study the problem had more of a human focus than a historical one.
In this regard, I have been very fortunate not to have such a sword of Damacles dangling over every grant RFP or grant award deadline, and to be able to research historic US Fish Commission records, US Fish and Wildlife catch statistics, USDA weather bureau climate records including NOAA records and have no concern over pleasing a funding agency.  I hope that the next generation of students in this marine history fisheries habitat area will have a far greater understanding of this research aspect.  This aspect is especially important to the growth of Aquaculture itself and increasing food from the sea (commercial fisheries) as it relates to marine soils, energy pathways and the rises and falls of fisheries. 

We need to have clear and unbiased habitat information and that is lacking in many areas - in fact, historical documents often provide the clearest views and science without the bias are often excluded from review and not often included in today’s habitat climate discussions – my view, Tim Visel.

The 1880 to 1920 period has many connections to the 1972 to 2012 period here.  The 1890’s saw herring populations plunge, brook trout had declined for most instances considered extinct, (1901) lobsters died off and massive fish kills happened, but the shoreline itself was relatively stable – very few storms.  Pavilions and boardwalks were then built along the water’s edge.  Shore cottages were often erected upon barrier beaches that then showed year-to-year stability.  Winters were generally mild, gardens being active into December.  But the cold would return to New England in the early 1920’s and grow colder, stronger storms returned also.  Buildings along the shore would now be swept away by storms (see Clinton Harbor and the Great Heat) oysters, which thrived in the heat, now had a series of recruitment failures – sets grew weak and then disappeared.  This is now known as a negative NAO – a colder and more energy active cycle.  The cold storm periods intensified between 1955 to 1965 – 1958 would see US shad production peak – bay scallops in Southern New England also.  They both thrive in cold high energy periods.

The great white shark population, which grew in the heat, now sought food in the shallows – great white attacks in 1916 off the coast of New Jersey (which inspired much of the story board for the movie “Jaws”) killed several swimmers.  Tarpon, long known in the tropics, were caught in Rhode Island waters in 1906 and Connecticut built a lobster hatchery in Noank in 1910.  Brown and rainbow trout were introduced into Connecticut in 1898 as it was thought that the streams were now too warm for brook trout, a native species.  Bay scallops in the hot 1890’s disappeared.  Only in the cooler northern Massachusetts Islands did bay scallops hang onto the last suitable habitats.  Striped bass that grew to huge sizes in the 1880’s now seemed to be scarce along New England shores.  But these were the great times for the blue crab.  Buzzards Bay in these warm 1900’s became a significant producing area.  We had seen this pattern repeat a century later.

Smelt once abundant in Connecticut even into the early 1970’s vanished in the hot summers of 1980’s.  They have yet to return to our shores.  But it is now turning cooler, after 2012 our waters have cooled slightly as snowfall increased.  Strong powerful storms have retuned as well.  We seem to be at the edge of cooler time, good for lobsters but perhaps not so good for blue crabs, which surged after the 1998 lobster die off. 

All these changes can be associated to the climate cycle we call the North Atlantic Oscillation or NAO.  The NAO also provides us a rare insight about the danger of a warming planet.  We need to review this climate feature to better understand our inshore fisheries – my view, Tim Visel.

Appendix #1

EPA Science Inventory National Health and
Environmental Effects Research Laboratory


Walker, H A. THE ROLE OF THE NAO IN NEW ENGLAND'S CLIMATE. Presented at New England Regional Assessment Meeting, University of New Hampshire, Durham, NH, January 8, 2001.

We are currently in a period of rapid climate change. The global surface temperature is rising with the greatest warming during the 20th century occurring over land masses in the Northern Hemisphere during winter. Stratospheric temperatures have cooled, which is another predicted consequence of increased concentrations of greenhouse gases, which absorb outgoing infrared radiation in the lower atmosphere. Based on recent results from three stratospheric models and two tropospheric models from the Goddard Institute of Space Sciences, greenhouse gas induced cooling in the stratosphere has affected stratospheric pressure gradients and is related to observed strengthening of stratospheric wind vortices around both poles. This polar vortex strengthening is associated with changes in the characteristics of the winter North Atlantic Oscillation (NAO), including a shift into a relatively persistent positive NAO index phase, and shifts in regional climate around the North Atlantic. To the north, recently declassified data from the Arctic indicates sea ice thickness from the ocean surface to the bottom of the ice pack has declined by 4.3 feet (40 %) since the first measurements were made in 1958. To the south, between 1960 and 1990 the winter sea water temperature of Narragansett Bay has warmed by 3 degrees centigrade in a shift from negative to positive winter NAO index phases. NAO variability is also associated with variability in storminess over the North Atlantic, and regional shifts in moisture flux, affecting both terrestrial and marine ecosystems. A shift into more persistent positive NAO index phase in recent decades is associated with generally wetter conditions along much of the U.S. Atlantic coast. Persistent negative NAO index phases such as in the 1960s are associated with regional drought in the Northeastern U.S. Future regional shifts in climate are not yet predictable but could include more persistent positive or negative NAO index phases. Hence, it may be prudent to plan to minimize environmental and health risks associated with both wet and dry extremes of regional climate.

Product Published Date: 01/08/2001 Record Last Revised: 06/06/2005
Record ID: 80524

Appendix #2
Our Future Salt Marshes Part 2
Manmade Marshes for Maine Waterfowl Game Division Bulletin No. 9
State of Main, Dept. of Inland Fisheries and Game, 1963
As the 1930’s and 1940’s at times produced very cold winters often areas and ponds froze over, and while duck hunting was fantastic in the very warm 1890’s, now was often poor.  Hundreds of hunting clubs noticed the reduction in ducks and exchanged notes and soon coastal managers (including the US Fish & Wildlife Service) initiated programs to enhance duck hunting habitats including important forage grasses.  One of the first efforts was that of Clarence Cottam.  Dr. Cottam followed the shooting reports of coastal duck hunting clubs in 1929.  It was Clarence Cottam who linked the forage grass “eelgrass” as an important forage for Brant, a frequent target for duck hunting clubs.  Programs started in 1939 under a grant program titled Federal Aid to Wildlife to improve waterfowl habitats. This often included digging out peat or impounding water to create more open water.  In a 1963 State of Maine Department of Inland Fisheries and Game Division Bulletin No. 9 (Federal and to Wildlife Restoration Project 60-37-R) states:
“Many and varied objects ranging from research on duck foods to the purchase and management of marshes have been carried out. These have benefited the waterfowl resource in Maine and throughout the flyway.”
But this report included efforts to change water habitats and influence forage plants for ducks. A large picture showing a bulldozer moving earth and water with a caption, “Birth of a Duck Marsh” is on the front cover page. The manmade habitats included impounding water so it would not freeze over.  The link to forage grass and open water was key to creating habitats for ducks.
The movement and depth of the water was key to duck habitats- and larger marshes tended to have more open water.  (This is often called “permanent water” in the waterfowl literature.)  Ponding water, so it would not freeze completely, was a key factor as once that occurred natural food supply diminished and why in the 1950s and 1960s you see programs to leave grain crops on nearby fields. (Ducks were at times forage limited as the often mentioned eelgrass/Brant, example). This is a section from the Maine Report that mentions this key habitat feature for ducks – a good supply of water. As the climate changed in the 1940’s, more and more duck hunting areas held fewer ducks. The cold had changed forage grasses and in winter froze over completely.  Sometimes ducks starved.  The section below highlights this concern:
“Water supply – Data collected regarding the water supply of the various areas were limited to observations made during the period of study. As pointed out in a previous section, the water situation was highly variable – particularly on the natural index marshes. Natural waters originated from small drainage patterns in most cases and some were also spring fed. The reliability of the water source seldom failed but some beaver dams and non-wildlife man-made control structures did deteriorate or cease to function in several cases.  As a consequence, the related waterfowl breeding areas dried up or became much less attractive. This aspect of natural vs. man-made breeding areas should be weighed when appraising the merits of marsh construction. Since nearly all the wildlife marshes were designed and constructed in accordance with the manual developed by the Atlantic Waterfowl Council (1959), the water supply was usually more limited than on the natural areas. In only one case did the supply prove inadequate. This occurred on an Aroostook County marsh where unusual soil conditions not detected in the original survey caused excessive seepage and the existing water supply was insufficient to maintain desired water levels. In two other cases small marsh control structures failed due to frost and ice action.”
In other areas such as Barn Island, CT, a famous case history was brought to the public by William Niering of Connecticut College – areas were improved to hold water to increase duck habitat.  Interest and support of hunter’s federal taxes on shot guns, hunting ammunition and related sports equipment. The Federal Aid in Wildlife Restoration Program was a dedicated fund to purchase and improve habitats for duck hunters. The original Congressional Act, the Pittman-Robertson Act provided funds to purchase land (duck habitats) so that hunting could be improved. Many of the sanctuaries and habitat refuges were purchased from hunting taxes to support habitats and enhance the hunting of ducks with bag limits and seasons.
As winters became more severe, ducks that needed open water to feed on diminished resources, a forage collapse occurred, and to counter this lost food, supplemental feed programs usually with cooperative agreements were made with nearby farmers not to harvest grain crops – leaving them as food for ducks similar to the Audubon programs during the same period - winter bird seed feeders, these programs helped, but shallow marshes froze over and the ducks left.
It is at this time that efforts to impound water, make existing open water deeper or take marshes and flood them to make habitats to withstand the changing colder climate cycle - as compared to duck hunting in the 1880-1920 in which duck hunting (and ducks) thrived. The number of sports clubs (shooting clubs) at this time served as a sport or recreational activity and market duck hunting (25 bag limit) was ending along the Atlantic flyway. You also see in state reports efforts to release game birds to satisfy hunting demand with lower bag limits; in the early teens, many sports clubs consisted of Civil War Veterans that formed around the turn of the century.  With the demise of the passenger pigeon around 1910, most states restricted or eliminated market hunting.  The term “bag limits” refers to the number of and species of ducks carried in a canvas shoulder bag.  The term bag limit did carry over at times to the shellfisheries.  While these programs limited the commerce of market duck hunting, it created a demand for farmed ducks and areas such as Long Island, NY near or located on water bodies now raised ducks for food.

Appendix #3


Review of Oxygen Depletion and Associated Mass Mortalities of Shellfish in the Middle Atlantic Bight in 1976

ABSTRACT-In summer and autumn of 1976, mass mortalities of shellfish occurred in a 165-km long corridor of severe oxygen depletion paralleling the New Jersey coast from 5 to 85 km from shore. Mortalities of surf clams, Spisula solidissima, the most severely affected species, were estimated in excess of 140,000 t. Alteration of normal migration patterns of lobsters and several species of finfish was also noted. A series of anomalous meteorological and hydrological events (particularly early warming of surface waters resulting in early thermocline development, and a massive shelf-wide phytoplankton bloom) superimposed on an already stressed coastal area, was considered to be responsible. The occurrence is particularly significant because the continental shelf of the Middle Atlantic Bight, from Cape Cod to Cape Hatteras on the east coast of the United States, contains the largest known stocks of ocean shellfish of any comparable coastal area of North America.

Mass mortalities in the sea are relatively common events and always attract the interest of the scientific community as well as the public. This interest may be based on a concern for the loss of a fishery resource, or the nuisance or health problems created by the decaying animals. Very often it is difficult to identify the cause of mass mortalities because most investigations begin after the fact, so the conditions, which lead to the mortalities, may have been altered or dissipated by the time studies begin. The majority of mass mortalities are very localized, often confined to a particular bay or estuary, but a few can be widespread, sometimes affecting hundreds of square kilometers of ocean.
An environmental event of heroic proportions, leading to mass mortalities of many marine species in a 12,000 km2 area of the continental shelf off the Middle Atlantic coast of the United States occurred during July through October 1976. Investigators were able to detect conditions that were lethal to marine life; these conditions were extreme oxygen depletion and hydrogen sulfide formation in bottom waters.

In the central part of this zone, oxygen values were zero, and hydrogen sulfide was detected below the thermocline. Oxygen depletion persisted until October, when lower surface temperatures and mixing, after disappearance of the thennocline, gradually reoxygenated the bottom water. Mortalities of fish, lobsters, molluscan shellfish, and other benthic invertebrates were observed. The sedentary forms, surf clams, ocean quahogs, and sea scallops, suffered the greatest mortalities. From almost continuous surveys, it was estimated that 69 percent of the surf clam population off the New Jersey coast, representing some 143,000 t of meats, had been destroyed by October, with significant but lesser mortalities of ocean quahogs and sea scallops. Lobster catches were reduced by 30 percent during the period. The New Jersey coast was declared a resource disaster area in November by the Federal government because of this event.

Hydrogen sulfide was also evident in an apparent upwelling of anoxic bottom water along very restricted portions of the immediate shoreline in central New Jersey. Hundreds of fish of several species, including sharks, were trapped along the beach and killed. A period of strong westerly winds, pushing the inshore surface waters offshore, was thought responsible.

EFFECTS ON SHELLFISH AND OTHER BENTHIC POPULATIONS - Beginning in late July 1976, assessment of the impact of the anoxic event on the surf clam stocks began. Signs of stressed surf clams were noted by divers as early as the weekend of 4 July. These were clams that were not embedded in the sediment but were lying free on the surface. Several later trawl surveys also found live, but gaping clams.

The lobster, Homarus americanus, industry off New Jersey suffered. Some of the inshore stocks were killed, and the annual shoreward migration of offshore stocks was interrupted. During the months of June through September, normally the most productive months of the year, landings declined an average 30 percent compared with the same period /978 KILOMETERS 020406; 10 20 30 NAUTICAL MILES NEW JERSEY 74° period in 1975. The inshore pot fishery, which operates within 20 km of shore, was most severely affected. Lobstermen stated that few offshore migrants entered the fishery in 1976 (Halgren, 1977).

Other benthic populations were affected by the anoxic water. Effects on the benthic infauna were most noticeable in the H2S zone, with reduction in numbers of species and numbers of individuals. Species to species variability in survival was noted, with a number of polychaetes and sea anemones quite resistant to prevailing extreme environmental conditions.

The survival of marine invertebrates, including shellfish, in oxygen-depleted waters, and in the presence of hydrogen sulfide, has been examined, and additional experiments are being conducted by the National Marine Fisheries Service. Earlier studies (Theede et al., 1969; Davis, 1975) and preliminary results of current studies indicate survival of clams for periods of several weeks in water which approaches zero D.O., but shorter survival in hydrogen sulfide environments. These experimental findings agree with field observations in 1976. Surf clams began showing signs of stress early in July, but mortalities were not reported until the middle of July. The extended period of anoxia, combined with hydrogen sulfide, resulted in 100 percent mortality by October at stations in the most severely affected zone along the central New Jersey coast.

Oxygen depletion has occurred sporadically in Mobile Bay, Ala., one of the largest estuaries on the Gulf of Mexico. Stratification of the water column over highly organic bottom results in summer oxygen depletion, and occasionally, because of winds, the water mass impinges on beaches. Fish and


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