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« on: October 25, 2018, 12:54:01 PM »

Peat Sapropel and Blue Crabs
 Environment/Conservation #17-A
The Blue Crab Forum (TM)
Sapropel/Eelgrass Peat Bacterial Processes Produce Sulfides Toxic to Fish/Shellfish
The Release Ammonia and Aluminum in Subtidal Composts
Peat and Marine Soils and the Sulfur Cycle
Tim Visel – The Sound School, New Haven, CT
October 2018

View All Bacterial Nitrogen EC Newsletters on the Blue Crab Forum™ (Environment Conservation Thread).  The views expressed here do not reflect the Citizens Advisory Committee or Habitat Stewardship Working Group of the EPA Long Island Sound Study.  On February 16, 2016, and February 8, 2017, I have asked Connecticut resource management agencies to recognize Sapropel as a distinct subtidal habitat type.  This is the viewpoint of Tim Visel. 

Environmental and Conservation Thread #13 Blue Crabs, Salt Marshes and Habitat Succession was posted on July 13, 2016, and should provide an introduction to this habitat history concept. It has been one of the most viewed posts to date.

A Note From Tim Visel

Blue crabbers are correct about their concern for current (river) driven organic matter being deposited in shallow water.  Although this paper was started in September 2017, it does relate to the first paper in this bacteria/habitat series posted on this Environment Conservation thread of the Blue Crab ForumTM titled “What About Sapropel and the Conowingo Dam?,” September 2014.  For the second time, August 2018 since tropical Storm Lee (2011), however, massive amounts of wood and plant tissue are being swept into warm low energy (poorly flushed) areas in upper Chesapeake Bay.  Not only does this suffocate current benthic life (seals it from water dissolved oxygen), but it also enables sulfur reducing bacteria and other harmful bacteria to grow, particularly Vibrio species that thrive in low oxygen and high organic matter habitats. 

Sudden floods have the ability to move enormous amounts of cellulose in many forms (whole leaves, ground up grass cuttings, animal waste, sewage, nuts, bark and twigs from trees) and blanket the bottom, suffocating any present marine grasses and sealing marine soils from oxygen, killing those oxygen-dependent species as well.  I often use the example of a neighbor suddenly depositing four feet of compost on top of your producing vegetable garden.  While it is true that compost “technically” is a good thing for terrestrial garden soils, the amount and sudden placement has dramatic negative habitat consequences for both land and marine soils.  The vegetable garden aspect is now changed and perhaps for several years unless the excess compost is quickly removed.  In this process, the vegetable crop for one year is likely lost.  In the marine environment, “low energy” or poorly flushed areas tend to collect plant tissue, the first step in building sapropels.  What could be “good” blue crab habitats in well-circulated bays and coves in cool conditions (degree of oxygen saturation – colder water holds more elemental oxygen), in stagnant waters with heat can now turn deadly – less oxygen and more sulfides, the condition of hypoxia.

While spring floods have brought floating wood surface debris to public attention, rains (floods) move millions of tons of organic paste into estuaries, unseen and rarely documented.  This is often the difference in the historical fisheries literature of “live” bottoms versus those as “dead” and why, in heat today, dead zones at the ends of this organic flows (rivers) grow bigger and why in cold, they tend to shrink.

Blue crabs live in or near peat for most of their life cycle, but only burrow into it for hibernation.  It does not create holes in the peat as other crab species, such as the fiddler crab or purple marsh crab that aerate marsh peat with their burrows.  Blue crabs don’t burrow deep into the peat; they just live over and around it.  Lobsters are known to also burrow into firm mud and move to the shore to release eggs.  Blue crabs do the opposite.  It is the peat that changes its chemistry in heat and cold, at times deposits of organics or other grass monocultures.

The chemistry of peat (sapropel) is linked to megalops settlement mortality (See Tankersley and Wieber, “Effects of Hypoxia and Anoxia in Callinectes sapidus,” Marine Ecology Progress Series, Vol. 194, 179, 191, 2000) and habitat avoidance may discharge chemistry cues as to hypercapnia (excess CO2 in seawater) and the presence of sulfides or ammonia.  Acidic conditions can release toxic heavy metals such as aluminum.

The blue crab may provide a unique indicator organism on how it responds to these habitat changes including floods could tell us much about the chemistry of marine soils – my view, Blue Chip – Tim Visel.
The Blue Crab and Peat

The blue crab may soon yield more than a delicious seafood dinner but help explore some of the most serious habitat questions of our time – climate cycles.  So much of that concerns how the blue crab adjusts to both cold and heat and can live in habitats dominated at times by sapropel.  It is the heat that brings the sulfur cycle back to a level it once has and ends oxygen life.  One of the parts of the sulfur cycle that had come into focus recently is the bacteria that “breathes” sulfate – not oxygen and the desulfovibrio bacteria that were here on the surface long ago.  Some bacteria strains can use both oxygen and sulfate, others use iron compounds as well.  The discovery of bacterial life by thermal deep sea vents shocked the scientific community in the 1980s by the presence of Vibrio bacteria living by them in such high temperatures.  This bacteria has been named Vibrio antiquarius, the Vibrio of antiquity.

Researchers are examining Vibrio species in deep cores of sapropel – some of which have been buried for centuries, others thousands of years.  Vibrio is also a concern to us as it is a pathogen to many marine species – even us.  Blue crabbers can come into contact with Vibrio species and sometimes with serious health consequences.  There have been numerous reports about crabbers that have contracted Vibrio, most from reported cuts and scratches.  In May 2018, NewsweekTM reported that the Florida Department of Health had issued a Vibrio vulnificus warning. People with open wounds can be exposed to Vibrio by direct contact with seawater.  This exposure, at times, can lead to life threatening infections (See Northeast Crabbing Resources, the Blue Crab ForumTM, Posted February 9, 2016, Importance Notice for Blue Crabbers, Estuarine Researchers, Megalops Special Report #1).

The blue crab lives in habitats that other species often finds unfriendly, the warm oxygen poor shallows that at times become sulfide and Vibrio bacteria rich.  Long before the blue crabs relatives developed wings instead of claws they were able to survive sulfide levels in which others could not – that is perhaps is how the blue crab survived, it held a habitat niche that few shared and in times of high sulfide (a robust sulfur cycle in oxygen poor waters) gave it an advantage that few could hold besides the eel or perhaps terrapin.  Blue crabs even have the ability to leave the water itself the so called “sulfide jubilee” when water oxygen levels reach close to zero.  It is the formation of sapropel, the bacterial reduction of organic matter without elemental oxygen, that drives sulfide levels which can kill many forms of sea life, even the blue crab – “the smell of rotten eggs.”

In the historical literature of New York bays and coves, you see eel, terrapin and the blue crab fisheries mixed from at times the same cove or bay (See US Fish Commission reports, New York Long Island sections).  The eel also have adapted to the same sulfide rich habitats by absorbing what little oxygen is present through its skin, by passing the gills.  This would give it a huge advantage and survive away from those large and more oxygen requiring predators – fish with teeth.  The eel has little defense mechanisms other than darkness and the presence of “smelly” mud.  This however is also the habitat of the blue crab, shallow, warm and therefore subject to lower oxygen and compost sulfides.  (Blue crabbers while crabbing often note the presence of large eels).  Key to this habitat niche is eelgrass that can provide the blue crab protection when small (to hide) and when adults feed in the sulfide compost below it.  Both the eel and blue crab have something else in common, they hibernate in it, the eelgrass/sapropel meadow and how eelgrass got its name (See IMEP #61-A Eels, Eelgrass and Bay Scallop Fisheries posted on the Blue Crab Forum™,March 28, 2017, Eeling, Fishing, Oystering thread).  But these habitats have a sharp edge for oxygen life and that is often temperature related for which the blue crab endures.

Blue crabs seek out bottoms that contain humus in winter and sapropel in summer.  If it gets too hot the sulfides can kill, if too cold the same thing may happen.  In the summer it is a blue crab jubilee – in winter a less emphatic term “winter kill.”  Here the winter does not kill the crabs directly (unless it was so cold they froze or so long the crabs starve which can also happen) but under thick ice in oxygen poor poorly mixed waters phytoplankton cannot get sunlight and they are killed by sulfide as oxygen levels drop.  When that occurs sulfide leaks into the water and sulfides kill and can even turn the water black.  Winter flounder also have the reserve pathway with specialized tail cells, like the eel so does the terrapin.  All three species have the ability to survive short low oxygen events.  Blue crabs here have an extra edge; they rise off the bottom (away from the sulfide) at night or even severe enough leave the water completely.  Many crabbers, during this early morning (oxygen minimum) period, notice that blue crabs hang on ropes and pilings off the bottom.  The rise of sulfides at night is also noticeable evidenced by the rotten egg sulfide smell of marshes in late summer when the water is warmest.  This smell often occurs just before sunrise.

Blue crabs and terrapins that are killed by sulfides often carry a black stain and smell of sulfur in early spring.  These organisms, at times, live in nature’s marine compost pile, which has the ability to change itself.  In cold, an oxygen-sufficient humus occurs with bacterial species that emitted nitrates (much like terrestrial composts) and in heat bacteria that produced ammonia, the land equivalent of “sealed composts.”  Even today, most gardeners realize the practice of turning or flipping composts introduces oxygen to help composting microbes (bacteria) reduce organic matter to nitrogen compounds – including nitrogen gas and nitrogen salts.  For the blue crab, a good fall humus can change to an oxygen-poor winter sapropel.  Most sapropels have a jelly-like consistency and smell “bad” from sulfides.  Sapropels, extremely oxygen poor, appear to be blue and alter the chemistry in it.

The formation of “nitre beds” for example in the production of saltpeter a key ingredient in the making of gunpowder was once the realm of the farm community and manure/composts for centuries.  This process took the bacterial residues of nitrogen/ammonia and controlled the bacterial community by allowing oxygen yet controlling moisture and sun light.  In Europe, farms harvested many acres of saltpeter manure beds called “nitre” the base word of nitrogen.  The blue crab lives in this “pre-peat,” these soft organic rich bottoms and the place of sulfide formation that kills submerged plants, such as eelgrass.

The availability of oxygen and moisture to soils has long been a concern in the terrestrial agriculture community but none so perhaps than the bacterial communities associated with grass.  Here this bacterial battle between bacteria types below soil surfaces influences the turf industry today – to wet and fungal infections create “fairy rings” in it, to dry and root health is impacted by peat chemistry (very dry peat repels water).  The health of turf grass root tissue is key to good grass growth and the ability to ward off infections.  Climate factors contribute to grass health and one that has extensive research in the soil/turf sciences.  Cornell University for example has assisted the turf/grass industry with detailed climate warnings (alerts) about soil conditions (See “Shortcutt”) with a newsletter - an in season weekly management tool for all turf grass managers issued for 19 years.  The newsletter is an excellent climate notification system on heat, soil temperatures moisture and suggestion on how to aerate root peat (now termed aerification) turf root zones for best grass root health conditions – all requiring mechanical energy.  Core punchers or drills into root peat are methods to improve turf grass root health today by allowing air (oxygen) movement into the root peat.  One of the methods used today to improve turf/grass root health and prevent soil compaction and increase pore/air exchange includes the use of high pressure water (maintain safe sports fields soil cultivation) “injecting high pressured water into the soil through small diameter nozzles opens channels for roots to grow with limited disruption of the surface.”

This is the same impact from coastal storms upon eelgrass peat/meadows and the aeration of marine soils via shellfish harvesting.  The first hard clam hydraulic harvesting dredges compared exactly to the use of hydraulic aeration of marine soils.  In cultivated marine soils, eelgrass thrives and is important to the blue crab.  The rise and fall of eelgrass shares many of the same marine soil characteristics of terrestrial peat – long subject to soil science study.  The sulfides that damage terrestrial grasses (turf) are the same chemical compounds that harm eelgrass as well.  This is a part of the bacterial (microbe) spectrum that includes bacteria that use sulfate dissolved in seawater for respiration and by doing so release sulfides into marine soils.  This occurs in both marine and terrestrial peat when oxygen is limiting and subject to the sulfur cycle.  This is a part of marine soil “health” as well important to overwintering blue crabs.  Very long cold period soil sulfides tend to increase as plankton growth slows.  If the cold persists, sulfides increase and can kill blue crabs in hibernation (i.e., winter kill).

This aspect is much understudied today (my view) what is the habitat quality of the organic deposits in which blue crabs hibernate?  These areas covered in ice (and tend to be in shallow water) obtain fresh water and ice forms first – these shallows could sustain greater winter kills, while deeper areas may contain more organic matter and yet remain ice free.  They are warmer and subject to more mixing. This could help explain the waxing and waning of eelgrass habitat coverage – as warmer winters chemically change the characteristics of subtidal peat (eelgrass meadows) and deeper areas perhaps a lower pH reverses the process.  We may be able to map this organic compost change over time and by doing so unlock some of habitat features that enables blue crabs to survive and why at times excess organic matter is a negative habitat consequence for submerged grasses.

If we can issue terrestrial turf peat grass habitat warnings perhaps the same for eelgrass marine peat?

I respond to all emails at [email protected]       

The Sulfur Cycle and Habitat Succession

One of the concerns of John C. Hammond on Cape Cod was the return of the sulfur cycle.  The sulfur cycle was a signal to him of a large habitat reversal and an end to most oxygen requiring “life.”  An example of this is the blue crab jubilee of southern areas; however in New England, it is the buildup of sapropel fine grain particles of clay and plant tissue.  This the bacterial release of sulfide often observed in salt ponds sealed from tidal exchange.  These areas are commonly called areas of reduced flushing or increased residence time – (particles) when certain substances can accumulate and in heat purge sulfides.

Hydrogen sulfide is a natural substance and highly toxic compound in both aquatic and terrestrial environments.  Hydrogen sulfide binds with iron altering the chemistry of blood.  We can detect hydrogen sulfide at about 1 part per billion (ppb) – (rotten egg smell) causing at 10 to 15 parts per million, nose, eye, and throat irritation, and anything above that has severe medical impacts.  Breathing concentrations over 150 parts per million is extremely hazardous – people are killed by breathing hydrogen sulfide in closed air spaces generated by sulfate reducing bacteria (SRB), Kong (1993) found toxic impacts of hydrogen sulfide to blue crab megalops at only 10 parts/billion.  One of my Florida Institute of Technology teachers (Jensen Beach Florida 1973) remarked about the Tampa Bay effect of sulfide smells in heat “by the time people smell it, the fish have felt it,” and by the term “felt” it meant “fled” or perished what we know as a “Blue Crab Jubilee” great for catching adults except for many young crabs it meant death.

It was the shallows that gathered most of Mr. Hammond’s attention, as he could see the changes that most people could not.  His many years of oyster culture gave him his observations of the marine soil in which he grew shellfish.  These observations changed over years and seasons.  He noted as many inshore fishers the habitat “pictures” over time as a long change cycle as opposed to brief “snapshots.”  People would visit Chatham (Massachusetts) for a week or a few days and that snapshot would forever remain a fixed moment but that would be all – a point in time in along continuum of different pictures at different times.  And the sulfur cycle he often mentioned in the decades to come would return in full force and change the habitat picture again.  The trouble was the length of time – for him it was a century.  It was Mr. Hammond who urged me to closely examine the 1880 to 1920 period as only long-term “views” could provide an appropriate movie for understanding habitat of change.  Habitat change and value was not static but changed over time and the ones who had the most accurate habitat picture were the ones who had the most photographs, the small boat fishers of bays and sounds.  Like farmers who could watch crops grow and monitor soil conditions inshore fishers could see the bottom while fishing and by doing so could take “photographs” of habitat change over longer periods of time.  I have seen those habitat changes myself.

I think that is why while growing up at the shore in Madison, CT (year round) summer visitors at times would visit the shore in winter and walk to the beach only to ask later where is it?  I would point to the sandbar offshore – “there it is out there.”  I recall some reactions, complete surprise for them the winter beach profile was now four feet lower, and a wood ladder built on a jetty was now the only way to cross.  In summer the sand almost hid the ladder and I am certain no one really noticed it.  But in late March after the constant pounding of Northeasters the yellow beach sands of July was now gone – largely replaced by beach cobbles and pieces of seawalls of long ago.  I guess, I could have blamed some other entity, a new seawall perhaps or just that someone came down and took the sand.  In the absence of any information some information was plausible at least for a while but I never did that I usually responded with something like “its natural,” the winter storms take the sand offshore but by June it is back – no worry by the summer the beach will be here when you visit – it is like this every winter.

They seemed greatly relieved – the snapshot they held of the beach of July was far different than the picture in March. The belief that the sands never moved created a bias that the beach always remained the same – the July photographs every year were nearly identical and no one was there to qualify or explain the seasonal difference.  I am certain that some visitors went back with startling images and accounts of no beach at all.

But what if I offered a different explanation, perhaps a non-natural one – one that involved human actions like a misplaced seawall had caused erosion, or that someone had harvested the sand leaving nothing but the cobble stones below.  They could have been plausible explanations and in the absence of a complete habitat history and believable for a while.  In a few months a summer visit would find much of sand back, and these non-natural explanations would be questioned.  But what if it was a 25-year cycle or a 50-year one?  The time it would take for my explanations to be disproved could be decades in length, and overtime, who would know?  And in the meantime investigations could be launched, committees formed, research projects submitted and grant money obtained – all to respond to a simple question “where is the beach.”  The short-term view of nitrogen is no different, heat has a huge role in nitrogen cycling but it is often missing from short-term surveys.  In some reports, it (heat) or temperature is not mentioned at all.

This scenario is a serious one and one that Mervin Roberts of Old Lyme mentioned in his book titled The Tide Marsh Guide to Fishes – Saybrook Press 1985.  On page 354 is found this section about populations and surveys:

“Biological surveys and consensus are difficult and sometimes impossible to carry out so as to be free of bias.  Examples of bias in science are sometimes found in collections of living organisms where population is in motion.  To be without bias, such a collection would have to be made over an extended period with no regard to inclement weather ice, time of day or holidays.  Consider the swallows at the Capistrano mission in California, how would a report on their habits look if no observations were made during those few days when they were all arriving or all leaving?  Consider a fly hatch on a trout stream, all over in one day, only once a year.  Consider a run of river herring, if you miss it, no one will be able to make you believe it.  I submit that we have no business establishing rigid categories for the works of mother nature.”

This aspect is what led to the German forest dieback controversy termed “Waldsterben” when German forest suffered a dieback in the 1970s now linked to drought.  It is also present in reviewing nitrogen/plant/algal responses in lakes and ponds.  In cold temperatures bacterial action slows, waters are often clear, but warm those same waters and bacterial action increases waters appear “cloudy” with plants with faster nitrogen cycling from the digestion of cellulose – plant tissue.

Unfortunately, we had a situation about the short term promotion of eelgrass and submerged aquatic vegetation – that it as a habitat type and deserves special recognition and regulatory authority and whose rise and fall is largely human caused and beyond the natural fluctuations of nature (my view, T. Visel).  Marine plants over time, in fact, create a root thatch, and in many areas a peat.  Peat is a term used to describe root and plant tissue in which clays and minerals collect.  The peat bogs have the sulfide cycle buried below out of sight and rarely considered in many habitat studies.  But when this peat gets hot, the sulfur cycle emerges as eelgrass and other SAV helps gather organic matter into peat and welcomes the sulfur cycle back, well not as a frequent visitor but makes a home for sulfur reducing bacteria – deep below the root thatch of eelgrass.  Here is the bacterial reservoir of sulfur reducing bacteria, sealed from oxygen but access to sulfate its source of oxygen and with it sulfur.  Here this bacteria wastes hydrogen sulfide into the water, and if high enough, kills the eelgrass and emits sulfide concentrations into the air.  When that happens, if long enough, the smell of rotten eggs – in heat waves, is the sulfide gas that moves from the creeks and marshes into coastal homes.  When coastal residents smell sulfide, its toxic impacts have already taken a toll on seafood. 

In June 2012, very hot weather created a hydrogen sulfide event in Stonington, CT (The Day (newspaper) “Odor Raises Stink In Stonington, CT,” J. Wojtas).  The source was identified as rotting algae in low oxygen waters, and the article concludes “that a small shoreline area with little tidal flushing was thick with seaweed and the slight odor of rotting eggs.”  The Day newspaper article then gave an explanation what is hydrogen sulfide – “A toxic flammable gas that can be a product of decay, organic matter especially in low oxygen conditions.”  It can be smelled at one part per million.  What isn’t mentioned is that sulfur-reducing bacteria (organic matter reduction) do not need oxygen.  They thrive in low oxygen waters, and because they use sulfate to breath are, in fact, a part of the sulfur cycle that reappears during heat.  As such, the amount of ammonia soars, feeding macroalgae as reported a century ago in Connecticut coves (See Quiambaug Cove, Appendix #2).  Macroalgae blooms often occur over or adjacent to deep sapropel deposits when they purge ammonia, often in high amounts.

Black water or sulfide jubilees have been in the blue crab fisheries literature for two centuries.  Areas to our south especially but during hot cycles in New England they also can occur here as well.  We call them fish kills.  Names of bays, coves and creeks sometimes give clues to them, none more obvious than the large reserve called the Blackwater National Wildlife Refuge of 28,000 acres on Maryland’s Eastern shore – often termed the Everglades of the North.  Here, the Black Water River and Little Black Water River feed this large marsh (peat) area, with the names attributed to the tea-colored water of these rivers from the tannin (oak leaf tea) flows through peat soil in the marshes.  In Connecticut, Native Americans once called the Niantic River “Black Bay” for likely the same reason.  The point of land to the west of Niantic River still retains a reminder of this name; it is still called Black Point.  Names like Deadwater River or fish kill creek provide clues of long ago.  They tell us just as we can observe them today that these habitat features (cycles) have happened before.  It is at these times the deadly sulfur cycle returns with heat to our shallow habitats.  Fishers experience these events.  What was a good fishing spot in May, may lack any fish at all in August.

In these hot waters, fish and blue crabs were often observed to flee, and waters with slower movement near or over eelgrass beds were noticeably warmer during field surveys of Buttermilk Bay on Cape Cod (T. Visel, personal observations, Cape Cod, 1980s).  Salt marshes are peat in the coastal region, cord grass (Spartina patens) is well suited to invade this peat and live on its surface as it can tolerate a segment of the sulfur cycle in high heat.  The sulfide browning occurs when the peat layers produces so much sulfide from sulfate reducing bacteria below consuming dead or organic matter that the plant turns brown and root rhizomes fail (collapse) as sulfuric acidic conditions weaken and then destroy root tissue. (Some New England reports have blamed blue crabbers for salt marsh diebacks – more about this in later reports).  On hot evenings coastal residents often mention a “bad marsh smell.”  {Along the coast historical oyster industry reports do mention hot stagnant waters and eelgrass over soft bottoms then rotting in association with sulfide smells}.  This is part of the sulfur cycle and impacts eelgrass health as well important to blue crab megalops.

This is the same process with submerged peat as eelgrass meadows in high heat suffer this same root failure and a weakened plant is now susceptible to fungal infections.  This fungal attack was evidenced by the eelgrass “wasting disease” of the 1930s.  Danish researchers, Jens Borum and Marianne Holmer, have recently reported extensively about dangerous sulfides accumulating in organic matter between eelgrass blades and amongst its root tissues.  In Europe expanding “death” or “fairy” rings of high sulfides can weaken eelgrass mono cultures and was the source of concern until it was noted that sulfides rings formation is a natural process that can also impact terrestrial grasses such as athletic fields as well.  In fact, turf rings are well known in the turf management field as sulfide damage from excessive rains.  Cornell University, for instance, issues Turf Alert advisories to warn turf managers of soil conditions that could damage sport fields or athletic grounds.  No similar turf warnings are available for fishery habitat specialists, monitored by the increase in sulfides.  The conditions of peat soils, to rot in heat or become powder-dry in drought, has been known for centuries.  Peats contain significant bacterial chemistry, which changes with temperature.   

While eelgrass holds and binds organic matter it forms a peat deposit and like all peat is now subject to bacterial reduction during periods of heat and few storms.  The sandy soil below emergent eelgrass is often slightly basic pH to acidic and alkaline at deeper depths as ammonia is produced.  This soil is described on pg 17 of the April 1958 reprint of a 1947 Soil Survey of Dade County Florida USDA Soil Conservation Service) and noted as “Davie Mucky Fine Sand.”  {Brackets indicate comments by T. Visel}.  Sharing some of the characteristics as submerged eelgrass meadows transitioning marine sandy habitats to sapropel.  Here Gallatin (1947) describes sandy soils bordering Florida Everglades peats.   

“This shallow peat layer of this soil has not yet been completely destroyed by fire or by slow oxidation {bacterial reduction – T. Visel}.  The soil is poorly to very poorly drained.  It is closely associated with the Davie fine sand and differs from that soil mainly in having a thin layer of peat or mucky material over the sandy layers”

And gives a profile description that includes a rising pH from ammonia.

“0 to 6 inches black muck or finely divided fibrous peat.
6 to 10 Inches, gray, nearly loose fine sand – slightly acid to neutral
10 to 30 inches, light gray loose fine sand, slightly acid but becomes neutral to alkaline with depth.”

This is precisely the same habitat succession reported by hard clammers (quahog) on Cape Cod in the 1980s, that many times (nearly all the time) beneath eelgrass meadows were found dead Quahogs and now black or grey sands stained by sulfides.  I have myself witnessed this habitat succession watching dredging projects in the 1980s in layers of muck between layers of fine grey sand.  Eelgrass ability to bind organics is found in the salt marsh studies of the 1930s publication titled “Recent Marine Sediments” (See Trask, Recent Marine Sediments 1939, pg. 436) on the subject of organic content of Recent Marine Sediments comments:

“In shallow water, shore plants such as eelgrass (Zostera) or mangroves may be the source of considerable organic matter in the adjoining sediments.  In fact, in waters around Denmark, Jensen (26) estimates that the production of Zostera amounts to 100 grams of organic matter per square meter” (Parker D. Trask, U.S. Geological Survey, Washington, DC, 1939).

This is precisely the same process of vegetation creating peat in the subtidal regions by one of the most aggressive high energy marine grasses, eelgrass Zostera marina.  Contrary to many reports eelgrass is not a species that typifies habitat stability – in fact it is a grass that thrives after a period of habitat instability moving into and colonizing recently cultivated marine soils with larger grain size and better soil pore water circulation.  Over time as eelgrass meadows rise they create “peat” roots hold mucks below that contain roots and dead plant tissue of reduced plant fibers.  In our area, the predominant oak forests contribute to this process as their leaves contain large amounts of leaf paraffins – wax esters.  It is these waxes that sulfate-reducing bacteria cannot digest – break down.  It is difficult for them to split these bonds so they just leave them behind.  In time, a growing deposit takes on a jelly-like consistency and, when disturbed, emits a strong sulfur or match stick “smell.”  In these sapropels, oxygen availability declines with depth and bacteria utilize alternate oxygen containing compounds.  Bacteria that can use (accept) elemental oxygen while some can utilize sulfate others nitrate in the process of consuming this organic matter as food.  Although many policies include bottom disturbance as a negative factor, eelgrass meadows (often) begin after such bottom disturbance from storms or dredging.  In a way these estuarine soils are cultivated by storms impacting “grain size.”  A June 2009 EPA publication mentions on page 5 possible limitations in the way bottom disturbance was to be classified in Long Island Sound habitats, linking sea floor habitat mapping protocols to management and policy needs (Auster et al., 2009; A Long Island Sound Study Technical Report – EPA Grant LI-971-50101).

“Variation in associated biological attributes linked to each sediment type, e.g. seagrass, American oysters, blue mussels dominated communities can be used as a fine scale classification element or a modifier of grain size.”

And further in a review of survey respondents over habitat classification approach on page 31,  “Differences in habitat classification approaches were also mentioned in terms of using soil versus sediment classification systems.”

And includes mention of including a possible chemical indicator for disturbance and exposure to air (oxygen) on page 40 is found in this comment.  (T. Visel comments).

“Others {survey respondents T. Visel} suggested wave disturbance, {Storms, T. Visel} presence/absence of long lived benthic invertebrates, bioturbation and presence/absence of sulfuric materials as a measure of the exposure to air as useful proxies.”

Or in a way the impact of organic matter and bacterial reduction and the chemistry changes from it was mentioned but did not recognize sediment as a soil and it could be altered by bacterial actions. 

The consequences and the negative habitat impact of oxidation of peat (salt marshes) and the change of chemistry in nearby areas was studied by some of the first peat researchers in the 1930s and 1940s and such as Selman Waksman at the Rutgers Agricultural Experiment Station.  The oxidation of peat and subtidal peat was studied by many Agricultural Experiment Stations for over a century.  When peat soils long removed from oxygen were re exposed to oxygen they could turn from something “good” into a source of pollution including ammonia and sulfuric acid.  Subtidal peat soils include those formed by eelgrass (SAV) over time in dense root/mats – thatch that require aeration for healthy root tissue could also do the same.  Here the definition of peat is “the formation is when plant material usually in marshy areas is inhibited from decaying fully by acidic and anaerobic conditions.”  Some of those peat definitions date back a century or more.  A New York report 1901 has the below definition.

“Peat – Marine Marsh Soils – these form a special type (submerged peat – T. Visel) which is found to some extent along the seashore.  They are formed by the accumulation of fine mud in sheltered or quiet waters along the coast.  On this mud flat the springs up a growth of eelgrass, which serves to entangle more mud and organic remains, thus raising the general level of the flat, and on this raised surface land grasses and plants spread out, forming a marine marsh” (University of the State of New York – New York State Museum 55th Annual Report of the Regents, pg. R-78, 1901).

It has been known for decades that eelgrass roots from a dense thatch and over times requires aeration such as terrestrial turf – as eelgrass peat grows they can change the chemistry and biological characteristics of the soil below (See Orth Reports, 1973-1997).  A dense bed of Zostera may effectively reduce were action near the bottom by buffering currents thus trapping and preventing removal of finer sediments – from Robert J. Orth, Benthic Infauna Of Eelgrass, Zostera Marina Beds).  And just us the peat formed with sulfate reducing bacteria once re exposed to air oxygen could emit poisons and toxins that harm not help shellfish and seafood species.  These bottom benthic changes can be subtle, apparent only to those who visit the same areas over time.  We have much more information on tidal peat (marsh peat) processes than subtidal ones (submerged peat).

The Connecticut DEP (now DEEP) office of Long Island Sound Programs made mention of the negative impacts of a lowered water table (more oxygen) and toxic salt marsh discharges in Guilford, CT two decades ago (Wetlands Restoration Investigation Leetes Island Salt Marsh, Guilford, CT 1994).  Very similar to Gallatin (1947) from the soil survey series in 1947 of Dade County Florida – USDA – Florida Agricultural Experiment Station – Series 1947 #4 on pg 18.  Here Gallatin et al 1947 in a discussion of Everglades peat includes this statement (T. Visel comments):

“Near the canals, where the water table has been lowered by artificial drainage, considerable oxidation {and reduction by bacteria T. Visel) of the organic matter has taken place.  As a result of this increased oxidation, the remaining peat has a higher mineral content, is less fibrous, {bacteria has reduced this surface plant fiber – T. Visel} and is more nearly black.”

On land, this black layer humus is found above these sandy soils washed from the glaciers about 10,000 years ago.  This topsoil is generally thin in New England because our soils geologically speaking are very “young.”  It is the “top soil” that is the result of bacterial oxidation but soils/organic matter under water have different and much slower bacteria.  Peat once exposed to oxygen (as compared to water- soaked, poorly drained peat – T. Visel) undergoes bacterial reduction almost immediately, including the formation of sulfuric acid.  In times of heat and drought, this peat could become so dry as to even catch fire.  I recall many mornings waking up in the FIT Jensen Beach Florida campus to a strange orange – red hue on the horizon (1973-1974) I inquired from some nearly residents about this strange color and sulfur smell and a simple response was “muck fires.”  I wondered how a wet muck marsh land could burn – that was certainly not anything I had experienced in the Madison, CT of Tom’s Creeks salt marshes but short trips west of the campus to Belle Glade and to Whispering Pines areas yielded peat that was completely dry, fibrous similar to potting soil – it was full of plant fibers but held little if any moisture (personal observations, T. Visel, 1973-74).  It was as they say “bone dry” and able to burn.  Although described as muck fires, it is better described as a peat fire; dry or hot conditions with a surface fire or lightening strike can ignite this very dry plant tissue and releases sulfur and metals into the air – we can smell the sulfur.  Wetland plants have adapted to bacterial chelators of metal ions, sulfur and phosphate and high water tables.  Over time, these peats collect and deepen, forming a “peat.”  Peat has been used as a fuel for centuries and I have many great memories of trying to start Irish peat fires in the 1980s with fresh cut peat (which of course needed to dry first).  “Surely you didn’t take the wet “peat” our Irish friends mentioned. Several Jensen Beach Florida mornings I would awake to the organic red slow and the smell of sulfur, the peat or muck could catch fire and burn for several days.

In the marine area – once “dried” or ditched and drained New England salt marshes (peat) could undergo this same chemical oxidation process.  The sulfate bacteria that could do this and as a result release toxic substances into the water column and change its chemistry of the by products certainly not as dramatic as fires but reduction just the same.  The Guilford CT study titled “Wetlands Restoration Investigation Leetes Island Salt Marsh Guilford, CT – Marsh 1994 US Army Corps of Engineers – New England Division – Section 22 grant program Connecticut.  This 1994 report contains a foreword prepared by the Connecticut Department of Environmental Protection (Now CT DEEP – T. Visel) Office of Long Island Sound Program for the Leetes Island report – and mentioning the Leetes Island Salt Marsh was drained in 1916 for salt marsh haying that draining and exposure to oxygen and faster bacterial reduction can cause marsh levels to sink – page 1 contains this quote (Author not mentioned in the manuscript):

“The most immediate consequence of this decomposition is a long term lowering of the marsh surface elevations, an effect called subsidence” and “the longer subsidence occurs, the less likely that the marsh can be restored.”   

The presence or absence of oxygen could be determined by lowering the water table – drying them out.  In these water soaked organic peats bacterial reduction would soon exhaust available oxygen and then turn to nitrate and once that was utilized – sulfate and sulfur reducing bacteria – much slower decomposers would in heat become more numerous.  Peat levels on the surface could now “rise.”  As the oxygen level increases or decreases in peat a bacterial “war” occurs in which oxygen requiring conflict with those who do not need it.  Subtidal areas bathed with seawater daily contain “non limiting” amounts of sulfate dissolved in it.  For bacteria that can utilize sulfate as an “electron acceptor,” they will never face a shortage in an oxygen diminished planet as these bacteria “will win” as mentioned in EC #8 posted on September 10, 2015 titled Salt Marshes – A Climate Change Bacterial Battlefield Blue Crab Forum™ on the Blue Crab Forum™.  When salt hay operations occurred, farmers along the coast often applied a thin coating of sapropel to replace “lost” organic matter.  Marshes were sinking and to make up for this organic matter loss they (farmers) often replaced it.

Unseen at the time was a bacterial battle in the peat itself as surface grasses gathered plant material, bacteria below were consuming it.  This “sinking marsh” was pointed out to me by Charles Beebe that the log road on the marsh of the lower East River, known as the “school marsh” – salt hay was once sold to fund Guilford’s first public schools thus the term “school meadows” remains.  The Army Corps of Engineers cut into the marsh to create a harbor of refuge in the 1950s, and when it did so. cut into the school hay road which was now six feet below grade a series of logs and slab wood road clearly visible preserved in the peat as sea levels rose the marshes over time had sunk – and in hot weather these deep sulfur bacteria strains now rise to the marsh surface – consuming the peat as they rise.

The consequence of this bacterial conflict is the rise and fall of peat but also contains direct habitat implications in the marine environment – toxic residues of the sulfur cycle.  The sulfur cycle vanquished, oxygen-requiring species as it sets off a chemical reaction that burns into it.  This is a much different type of combustion than with oxygen or the rapid oxidation of organic matter.  Here the sulfur cycle “burns” to produce toxic sulfides toxic to sea life and us. In the study of Mediterranean sapropels, this is termed as a “burndown” of iron sulfides (See Juergen Schieber, 2011, Iron Sulfide Formation, Encyclopedia of Geobiology).

The rise and fall of peat by bacterial pathways – one oxygen (the rapid pathway) or the one without oxygen (sulfate) which is for slower allowing for the buildup of peat over time is the same as the rise and full of sapropel/or sapropel – eelgrass and other submerged aquatic vegetation – its ability to change the chemistry of the soil.

The process of peat formation and references to it as a soil can also be found in the 1994 Army Corps of Engineers report mentioned above (foreword by CT DEP on page (1) has this section.  (Author not delineated).

“A variety of physical changes occur to the soil.  The soil in a salt marsh is known as peat, which is composed largely of the decomposing remains of plant material.  Organic peats only form when the soil is water logged and anaerobic (Low oxygen – T. Visel).  Under these conditions, iron combines with sulfate (a common constituent in sea water) to form the mineral known as pyrite.  Draining of the marsh causes the water table, which is normally within several inches of the surface, to drop several feet.  Thus the upper several feet of the soil are now exposed to oxygen or oxidized.  Under these conditions, the organic component of the soil decomposes at a very rapid rate.”

These changes in peat reduction has toxic residues which can at times kill oxygen requiring organisms larval forms, and changes the chemical characteristics of salt marsh habitats from positive to negative including the discharge toxic metals such as aluminum.  It is the source of the blue crab jubilees that occur in southern waters but occasionally here as well.  (Most Blue Crab Jubilee information mentions oxygen – poor bottom waters but do not include the sulfur cycle (See Jubilee Phenomenon – National Estuarine Research Reserve System – Estuary Education 27 pages – the words bacteria, sulfur cycle or sulfides are not mentioned).

What is missing from much of today’s blue crab jubilee literature is a mention of the sulfur cycle.  The reports about the blue crab jubilees include heat, low dissolved oxygen and organic matter – all appropriate but do not include the formation of sulfides only the smell of rotten eggs – a sign of sulfur reducing bacteria (SRB).  This happens when bacterial use oxygen to break down cellulose into edible sugars (think of bacterial culture dishes with agar – the components of sugar – galactose) and “waste” sulfides.

This is a situation when low oxygen (plenty of food (cellulose) the organic matter (sewage, leaves, bark, grass clippings, etc) with little flows, and stagnation (residence time of organic nitrogen) leads to increases in sulfur reducing bacteria and the production of sulfides – the rotten egg smells (See the Rock Creek Aerators of the Patapsio River, Pasadena, Maryland for a long-term habitat history).  Hydrogen sulfide can be so strong in these events to discolor paint on homes.

It was the sulfide smells on morning mists that alerted coastal residents that a Blue Crab Jubilee was underway – coastal residents need to know about the sulfur cycle in lagoons and bays (my view).  Here in these “stagnant waters” the first sapropels can form – termed black mayonnaise by crabbers and fishers.

The same bacterial reduction process occurs in areas with sulfate dissolved in seawater, and peat, the salt marshes themselves.  The only difference is the height of the organic matter (peat) the same sulfate reducing bacteria reactions apply – they can kill fish.  These fish kill references have occurred before the 1994 Leetes Island Report.   

A decade earlier similar salt marsh oxidation impacts were mentioned as being negative for fish.  In an article for the Massachusetts Audubon Society by Richard LeBlonde titled “The Diking of the Herring River” (Wellfleet Mass) in 1984 mentions the work of John Portnoy, a biologist at the Cape Cod National Seashore who was studying the impacts of the dike - -and contains the following section {Brackets indicate insertions of T. Visel}:

“Acid production {salt marsh} is a direct result of diking and subsequent ditching.  Salt marsh peat naturally contains high amounts of sulfide.  It is converted to acidic sulfate by exposure to gaseous oxygen, which occurs when the peat is drained of water.  This acid also leaches significant amounts of aluminum from the clay in peat.  Both sulfate and aluminum are toxic to fish, and only 0.3 part per million ppm of aluminum need to present to be fatal.  Readings as high as 49 ppm have been found in ditches behind the dike, where the pH is a highly acidic 3.2.  In 1980, several thousand American eels died in the river channel, apparently from the high acid and/or aluminum concentrations exacerbated by a below – normal water table.”   

When on Cape Cod working for the University of Massachusetts Cooperative Extension Service I had heard about these acid “fish kills” but did realize the implications of the sulfur cycle.  I had been exposed to acid peat in the cranberry industry but not as the sulfide/sulfate by products of bacterial digestion of the formation of sulfuric acid.  (The impact of sanding cranberry bogs to stimulate root tissue delays sulfide formation of the root tissue).  In our area of Connecticut, the cranberry industry once flourished and from time to time abandoned bogs still have cranberries. 

Once peat was drained and surface peat enriched with oxygen plants thrived (i.e. salt marsh hay) but with good growth came the need to nourish the peat, i.e. top dressing of sapropel.  In a rare account, Maine mentions “flats mud” and the use of lobster shell to neutralize the acids (oyster shell in other areas) from fish and Men in the Maine Islands 1880 (Bishop) in describing Deer Island farming “he put on his lands a top dressing of the refuse from the lobster factories and also flats mud which he found excellent.”

This is the same chemical reaction when farmers dug up or purchased sapropel as a soil nourishment for farm fields a century ago.  This organic/carbon ooze below tide level peat had yet to break the surface and when it did and exposed to oxygen it produces sulfuric acid.  If low oxygen conditions allow peat to accumulate what is the impact of low oxygen in these subtidal deposits – they also start to build – fishers now see in heat the peat formation on previously sandy or firm bay bottoms frequently called “black mayonnaise.”  If the impacts of oxygen availability increases in a salt marsh creating a low acid condition – it is now the same chemical reaction of a sulfuric acid wash after a storm or the lessening of hypoxic conditions – it is, in fact it is precisely the same.  If salt marsh (peat) oxidation can kill pelagic fish species what about benthic species in seawater which at times can become void of oxygen or have low oxygen conditions – in these instances sapropel (a subtidal ingredient for peat) just as its air exposed peat can now purge toxic substances, ammonia, aluminum and acids.

The Rise of Sapropel/Eelgrass Peat Occurs During Heat – The Sulfur Cycle

The 1870s were cold and storm-filled in New England.  One of the most dangerous bodies of water was Long Island Sound.  New Haven Connecticut a busy shallow draft port and had a times over a hundred moored sailing vessels waiting to pick up goods or unload them.  The first ports were more inland such as Fair Haven as rivers inland provided natural protection from rough seas and a shipping (commercial) wharfs – one in New Haven was called Long Wharf was often damaged by storms.  The 1870s storms were often accompanied by cold and ice damage to shipping, wharfs and lost vessels gave rise to the term “The Devil’s Belt” as the east west orientation made Long Island Sound more vulnerable to northeaster’s gales those low pressure systems that moved north/northeast of Long Island Sound.

It was the 1870s in which cold Canadian air energized the subtropical jet stream resulting in devastating coastal Northeasters.  It was the 1870s that started the federal response to protect shipping and trade we can see today as the New Haven Harbor Break Waters.  (Breakwaters would be also built all along southern New England coastline) but the federal response was slow it took decades for political consensus around funding and appropriations to be reached.  By the 1880s construction on the eastern New Haven breakwater system was well underway and finished by the turn of the century.  The problem was by the time the breakwaters were completed it was midway into the great heat, the 1880 to 1920 of warmer temperatures and few strong storms.  They (breakwaters workers) must have asked themselves why the need?  It must have been curious for those working on the last sections of these stone breakwaters built in New Haven now in a period of extreme heat and no storms?  The climate pattern had changed to a positive NAO and is suspected of drawing hot dry air across the country the westerlies, as compared to the horseshoe shaped storm track of the negative NAO (polar vortex) that allowed cold artic air to sag far south colliding with warm air energizing coastal storms.

The New England estuaries in the 1870s were generally cold – sometimes covered by thick ice and in spring subjected to powerful gales.  It is this time that barrier beach inlets broke as dense colder water scoured away soft organic deposits.  Oxygen was available and marine soils were often a sandy shelly grit, fishers once looked at soils as a way to find certain fish species by placing lard or butter in lead weights, that is how bottom samples were placed between fingers and analyzed for habitat types.  In this cold shallow bays now contained bay scallops, quahogs and winter flounder were caught in a type of trap called fykes.  That would all change in the 1890s – as warmer temperatures changed marine soils and at times the chemistry of seawater itself.  One of the historical attributes of this transition was the rise of sapropel covered by eelgrass reported by fishers.  The oyster industry noticed this change – rising temperatures had greatly increased oyster sets but also brought black bottoms that smelled – and in time diminished crops or killed oysters outright – the rise of sulfides.  Occasionally such black bottoms were linked to off flavors in seafood such as clams and oysters.  One of the best descriptions of sapropel came by an investigation of Long Island Sound (requested by the oyster industry) from dead and dying oysters.  New London Day article dated March 21, 1890.  Titled, “Long Island Sound Remarkable Revelation A Bottom of Putrid Things.” (It was a good title.)

It is in this period that soft organic matter covered sandy soils and allowed eelgrass coverage to greatly expand.  Into the 1920s eelgrass coverage had mostly likely reached its peak.  It moved into deeper waters, at times 75 feet, as described in the Torrey Bulletin Series by George Nichols (The Vegetation of Connecticut, page 523, 1920) - eelgrass blocked the famous Revere Beach in Massachusetts (also called Crescent Beach) and Samuel Cabot was determined to find a use for this abundant loose “weed” that now rotted in summer’s hot temperatures.  He was to create “Cabot’s Quilt,” the first batt home insulation with dried eelgrass stitched between Kraft paper™ in 1893.  As the climate changed again Southern New England had habitat instability – hot summers but now increasing storms followed by the cold cycles of the 1950s.  The sapropels of the 1880-1920 periods were now washed from bays and coves.

At the end of this hot period 1920, eelgrass had greatly expanded its coverage even out to depths of 60 feet or more (Nichols); fewer storms, it is thought, had made waters very clear.  After 1921, these conditions rapidly changed.  Constant cold allowed oxygen to penetrate eelgrass peat – sulfuric acids formed.  Weakened by this sulfide attack it is now thought that eelgrass succumbed to secondary diseases including the infamous fungus Labyrinthula zostera.  Stronger storms ripped up weakened eelgrass peat allowing more contact with oxygen creating a sulfuric acid “wash.”  This weakened the eelgrass that remained.  Waters now were turbid carrying the clays that accumulated during the warmer less stormy period.  In this heat, winter flounder moved offshore to the growing seed oyster beds, quahog sets declined and then became scarce.  Bay scallops in this heat slowly disappeared, but that was to change in the 1950s and 1960s as colder patterns returned (Blue crab populations in New England also declined during this time), and the bay scallop would suddenly “come back.”

In this transition from heat, heavy rains and stronger storms ripped up eelgrass weakened by fungal infections now suspected to be linked to sulfide toxicity.  Eelgrass/sapropel had covered or diminished habitat quality for the bay scallop that prefers alkaline soils and the presence of coralline red algae.  Narragansett Bay “deep water” scallop habitats of the 1870s were transitioned into sapropel/eelgrass peat by 1910.  The last deep water bay scallop habitats were gone in Narragansett Bay.  The deep water bay scallop fishery soon collapsed.  The heat caused changes in marine soils, quahog sets diminished there soon, and quahog populations shrank as fewer seed clams survived.  Fishers then caught fewer adults.  Some of the worst fish kills occurred during the great heat such as winter flounder fish kill in Moriches Bay in August 1917.  Some of the fish kills occurred in bays now choked with eelgrass – some coastal ships were even out fitted with special propellers so that vessels could cut the dense eelgrass meadows.  That all changed in the 1930s.

What had caused the rapid rise in sapropel/eelgrass was that marine soils were first cultivated and soil pore water filled with oxygen in the 1870s then became warm in the 1890s.  Eelgrass being an efficient (some would term aggressive) colonizer of cultivated {disturbed} marine soils moved into these rinsed and cleaned soils after the 1870’s.  In time as the eelgrass roots become established the blades trapped organics and in times eelgrass meadows would “rise” forming a subtidal peat.  This is habitat succession in the marine environment and the formation of peat, which now as a deepening compost covered once productive bivalve habitats.  This would be measured in decades.  But this natural process had created its own habitat clock, and the return of warmer temperatures and the collection of organics now speeded up its habitat successional clock for eelgrass.  The denser the eelgrass grew, the more organic matter it trapped, the sooner it rose off the bottom.  The greater the rise, the more chances it had of bacterial sapropel forming below it, leaking iron sulfides and creating the foundation for sulfuric acid - extremely low pH with toxic sulfides.  Hotter temperatures reduced oxygen water saturation, and eelgrass plants now stressed were subject to secondary infections from molds and fungus.  While many point to the fungus infections of the 1930s, these areas most impacted were the same that had slow moving waters, higher organics and putrid composts – forming sapropels. 

In these areas, eelgrass increased its habitat coverage, now gave it back in a cycle that is related to temperature and energy, indicated by the chemistry of sulfur – the sulfur cycle.  While this impact may take decades, a sudden dump or flow of organic matter can do the same thing, and “healthy” functioning eelgrass or other marine grasses good for shellfish and finfish in cool water are destroyed.  It is these areas in which the sulfur cycles cause a surge in ammonia and the increase of suffocating ammonia species such as Ulva (sea lettuce) and Harmful Algal Blooms.  This warm to hot negative “compost” impact can also last for decades and turn ”live” and productive bottoms into non-productive or “dead” bottoms found in the fisheries historical literature.  It is a sulfide blue crab jubilee that never goes back. 

It is these sudden habitat changes that are mentioned in the fisheries literature.  Eelgrass, then “clean and green” and an important habitat for many species in cool water changes to a brown and slime-covered grass that is infected by molds – the “brown and furry” eelgrass.  The wash of organic matter (floods) now buries submerged soils and the previous habitats (including seagrass) are now gone.  What would take time or a habitat clock (habitat succession) is ended by a sudden event, such as waves or rain from tropical systems.  Although with putrid muck, the immediate impact is to smother submerged grasses and oyster reefs; the organic matter continues to kill seafood as it now composts in low oxygen – the rise of sulfides, the purging of ammonia and the release of bound metals, especially aluminum – all toxic substances to oxygen-requiring life we fish for, crabs, shellfish and finfish. 

The mechanism of this killing field is sulfur (sulfate) in seawater, the source of oxygen for bacteria that need it as opposed to those that do not – each with its own habitat impacts – oxygen in cold and sulfur in heat.  The battle for seafood is actually a battle of bacteria and the battlefield is deep within organic matter composts, we call sapropels.  That is why heavy amounts of organic matter can change habitats and why so many references point to Agnes (1972) as negatively impacting blue crab habitats, but few mention any sapropel impacts, which over time are far greater – my view, Tim Visel.

I respond to all e-mails at [email protected].


“Relationship of Sediment Sulfide to Mortality of Thalassia Testudinum in Florida Bay”

Bulletin of Marine Science, 54 (3) 733-746, 1994

Paul R. Carlson, Jr., Laura A. Yarbro and Timothy R. Barber

My comments (    ) and identified as such (T. Visel)

Catastrophic mortality of the seagrass Thalassia testudinum (turtle grass, T. Visel) has occurred in Florida Bay since 1987.  Among the possible causes for Thalassia dieoff are increases in area, density and biomass of seagrass communities due to high salinities in Florida Bay, resulting from water management activities and a decade-long drought in south Florida (Zieman et. al., 1989).  The same authors have also suggested that the lack of a major hurricane in the past 27 years has caused high levels of inorganic and organic sedimentation (lack of soil cultivation – T. Visel) have restricted circulation (soil pore water exchange – T. Visel) and increased summertime salinity and temperature stress (conditions made worse in high heat – T. Visel).  A pathogen might also play a role in dieoff: Porter and Muehlstein (1990) reported the presence of a potentially pathogenic strain of the slime mold labrynthulla in lesions on thalassia leaves from dieoff sites.  Because many areas affected by dieoff are located far from potential sources of anthropogenic (man-made or man-caused – T. Visel) nutrients and toxic compounds, pollution i


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