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The Search for Megalops
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The Search for Megalops – Program Report #1 -2013 – Blue Crab Year
April 17, 2013

• The 2013 blue crab season and climate change. 2013 a key year;
• The discussions surrounding habitat quality and capacity for blue crabs;
• Could the 2013 blue crab year answer climate change habitat questions – Hurricanes and Blizzards?
• All about Sapropel and habitat questions from western Connecticut crabbers;
• Year class size reports are key to understanding Megalops survival – watch for year class divisions.

The Significance of the 2013 Blue Crab Season

As the 2013 blue crab season begins, it may be one of the most significant in 50 years. Last fall, Connecticut had an immense Megalops set, but that was quickly followed by a powerful hurricane, then numerous gales, two blizzards and a very cold winter.

Western crabbers had a poorer blue crab season (2012) with much lower crab populations, now linked to hydrogen sulfide questions, summer heat/ low oxygen and chemical concerns following a July 2011die off. Eastern Connecticut crabbers (2012) had a good late season, believed to be populations that overwintered in the Mystic, Thames and Pawcatuck Rivers, but it was late September to October, and cut short by the powerful October Hurricane, Sandy. Central Connecticut had overall the best crabbing 2012 and the blue crab population in the Connecticut River was again in the millions.

Conditions however could be very different in 2013 – testing some habitat indicators believed to be helping the blue crab and restricting lobsters- energy and temperature levels.

Energy levels have certainly increased since 2004 and temperatures also showing larger year to year changes – cold then hot, etc. The winters of 2010 and 2012 were some of the coldest in recent times.

As one climate period ends and another begins, it is often that such wide swings in temperature and energy levels occur. After the long heat of 1880-1920 it was quickly followed by a hot and dry period out west; the Dust Bowl of the 1930s and 1940s. The 1950s and 1960s were colder and storm filled here in New England and recalled for numerous hurricanes which followed the New England Hurricane of 1938 and then increasingly colder winters- The North Atlantic Oscillation (coldest winter 1957).

The 2013 blue crab year will follow an unprecedented increase in energy levels (storms) and one of the coldest winters in recent memory. A habitat transition may already be in place, reports last summer included large numbers of small winter flounder in eastern CT, and Niantic Bay had a modest bay scallop season last fall. Both species have benefited historically from lower temperatures and increased energy levels. Many Connecticut beaches were striped of sand exposing buried cobblestones of long ago, habitat changes were sudden and in many cases severe signaling the possibilities of a significant habitat “reversal.” The kelp cobblestone habitat has been found to be very important to juvenile lobster stages.
The 2013 blue crab year could be one of the most important observation seasons to date. All blue crab observations are important, perhaps more so in just a few weeks. Thank you for sending your reports to me at tim.visel@new-haven.k12.ct.us – See you at the docks! Tim

The Topic of Habitat Quality and Capacity

I spoke with dozens of blue crabbers in central and eastern Connecticut last summer; many of them were just introduced to the fishery here in Connecticut. Essex has become a popular place to crab and the late summer fishery, the last several years (except 2011) has been very strong. In fact, many visitors are shocked / surprised to see those blue plastic circular laundry tubs filled to the brim with blue crabs. Many of the comments are from southern visitors who lived in the Chesapeake Bay area, surprised to see something “Southern” here in New England. Last year was the same, and during blue crab banding demonstrations I spoke with some visitors who came north for lobsters but found blue crabbers instead. I suggested they continue north as Maine was having an excellent lobster year while ours (lobster population) now were at very low levels. It’s a question of habitat quality and capacity, I responded as the habitat quality for lobsters here declined from much higher water temperatures; the habitat capacity for the blue crab improved. I didn’t need to press the point as about a dozen crabbers were fully engaged in landing blue crab after blue crab during the discussion. Last summer, you need not understand the change in blue crab habitat quality; you could see the results of it here at Essex. Overfishing is frequently mentioned as a concern by visitors and often the exchanges that followed were more even puzzling. The blue crabs in the Connecticut River last fall found favorable habitat after the saline tidal wedge builds in late June and the runoff from spring rains subside. The crabs that arrive then can’t withstand the fresh water flows in the spring. Those who do find deep salt water pockets (mostly dredged channels) have a chance to survive, but most crabs leaving the Connecticut River in the fall will perish - sad but true.
I was much more concerned, I explained, with a habitat failure then upon the sizes (legal size, etc) the real habitat issue is for the young. A huge increase in adults and few stages between them is a habitat quality question, not so much overfishing. In Connecticut we have good resource regulatory provisions, such as returning egg bearing blue crabs and minimize sizes. These are good rules but do nothing to ensure habitat quality, those issues which impact habitat quality are not governed by us but by the natural world. What makes it more difficult to understand is that before a fishery collapses, the habitat capacity to sustain it collapses first. It is a cruel irony that this situation often favors the surviving adults (they are more mobile and do not need to compete for space and food) so catch rates of adults actually increases providing a sense of security when actually none really exists. The winter flounder collapse of the 1980s followed this pattern1. The huge increase in lobster production here in the early 1990s was the beginning of a region wide lobster habitat failure, and when it collapsed, the significance of juvenile mortality came into full regulatory view as landings plummeted. The fishery was not overfished, it had good management regulations the lobsters suffered from a habitat failure in Southern New England as they had a century before. It was now very warm again and with few storms habitats had changed, what was damaging to lobsters, high heat and soft bottoms would cause the largest increase in blue crabs here, also, since the last century. Lobsters and blue crabs had “reversed” abundance in Connecticut. A similar fate may now await our Connecticut blue crabs.

Could the 2013 blue crab year answer climate change habitat questions?
At the turn of the century winter flounder fishers and bay scallopers found disappointment in many Connecticut coves and bays. Following the cold and storm filled 1870s the 1880s and 1890s were much warmer and then very hot. The 1896 and 1898 heat waves in New England were record breakers for their time. Bays and coves turned black and began to smell of sulfur, the rotten egg smells so common along the shores. Besides the Blizzard of 1888, the Portland

Gale of 1898 (most likely a November hurricane) and two gales of 1903 and 1905, the 1880 to 1920 period was relatively quiet, storm free. But with this period came heat

1 (See Where Have the Winter Flounder Gone? (Visel, 2010). Fishers might recall catching bluefish packed with small winter flounder driven from nursery habitats in the 1980s. Winter flounder had to flee these nursery areas and face new predator/prey relationships.

waves that killed hundreds of people. National Public Radio NPR has a comprehensive report on the career of Theodore Roosevelt during The Great Heat Wave of 1896 in New York City. The eastern CT fyke net fishery for winter flounder had largely failed by 1910 – bay scallops were practically nonexistent.
But fishers also noticed some distinct habitat changes then; eelgrass which was almost cleared completely out of the coves by the 1870s storms was back and formed huge dense monocultures (meadows), Brant feasted upon this eelgrass and populations of Brant soared as conditions now favored lush eelgrass growths. Eelgrass meadows trapped organic matter, not disturbed by storms which then rotted and turned black in high heat. Oyster fishers at the time complained the most about these “new habitat conditions” and the first reports of ruinous black “mud” came from Great Salt Pond research in Rhode Island (1898) and the work of Rhode Island Experiment Station run by Dr. G. W. Fields. Organic matter washed into streams with manure, a dairy industry practice then and formed a slurry of rain driven organic oatmeal that buried previous “hard” bottoms and now were soft and sulfur smelling which killed river oyster beds. In the high heat this organic material started to rot and produce hydrogen sulfide, as recorded by the coastal residents who reported the “marsh stinks” the infamous rotten egg smells. That happens today also, and surprisingly Niantic Bay, Connecticut had a brush perhaps with hydrogen sulfide toxicity in August 2009. Then newscasts WTNH-New Haven contained reports of blue crabs crawling on land to escape the “low tide” Niantic Bay (River) waters with pungent smells. (Blue Crabs Picking Land Over Niantic, Friday August 7, 2009 by Jamie Muro). I believe this to be similar to more southern crab “jubilees” when blue crabs walk ashore by the tens of thousands. The August date and very hot temperatures suggests a hydrogen sulfide toxic “event.”

When coves turned black, sulfate reduction processes accelerated and fish kills soon followed- that was the 1890s. These conditions persisted into the 1920s (Grabau 1921).

But as oyster fishers complained about black muds lobster fishers also watched as their fishery collapsed, and the lobster die offs peaked between 1898 and 1905. Bay scallopers also were out of business, not from overfishing but because instead of cold water corraline reds algae and red weed (thought to be the real scallop grass) such as the deep water Narragansett bay scallop habitats were now covered with eelgrass and in high heat acidic conditions were lethal to bay scallop sets (dissolves shells). But as the bay scallop, lobster and inshore winter flounder fishers saw disappointing catches, those blue crabbing, catching soft shell clams, striped bass, and those involved in oyster culture on hardened bottoms were reporting very positive increases catches couldn’t be better. And for every acre of oyster and clam shells placed on aquaculture acreage, it buffered acidic marine soils for hard shell clams while creating more habitat for winter flounder.

The year following the Portland Gale, the Connecticut oyster set (1899) was to be the set of the century, soft shell clams set heavy on Cape Cod, blue crabbing soared region wide north even into Buzzards Bay and during this heat, striped bass grew huge. Many Connecticut River clammers converted their skiffs into guide boats to take New York hunters duck hunting in Connecticut River marshes no longer iced in as before, and now early “hot” springs made duck hunting and turtle trapping the business of necessity not choice. Noank, once of the center of Connecticut’s lobster fishery became a community of coastal cottages and the place to “torch light” blue crabs at night. Striped bass fishing became a popular past time for the then rich and famous. Many northern islands walking fishing “stations” were build (few storms) and the bait used to catch some of the largest stripers then that would be 2 pound lobsters or soft shell blue crabs. Fishers and hunters were in “The Great Heat,” a period in New England’s climate history of very warm hot summers and few strong storms. If you were to examine the lobster and blue crab fisheries today besides habitat quality indicators that are present today they will provide some answers to habitat questions asked over a century ago. What happened to the Southern New England lobster fishery in 1898 and a century later Connecticut again has experienced a lobster die off while an amazing surge in blue crabs. Why?

These habitat changes were signaled in both cases by the fisheries noticing bottom habitat changes, the muck that covered so many estuarine bay bottoms, and produced those sulfide smells, today that muck is called Sapropel and is the largest indicator we have to habitat reversals and fishery transitions. Fishers in New England wide raised the Sapropel alarm bell in the 1980s and looking back they were correct to do so. In one of the few case histories of this sulfur rich mud impacting fisheries could be the Long Island duck farms of the 1950s and 1960s. The appearance (or disappearance) of Sapropel may become a key indicator of climate induced habitat change. That case history is under review presently.

All About Sapropel – and Habitat Questions from Western Connecticut Crabbers

In July 2011 we had a large die off of adult blue crabs in western CT during a heavy rainstorm. It was hot; also a time of heavy West Nile reported chemical pesticide and reported application of brickets into street drains. A large migration of crabs had already left the Housatonic River and was heading east, and western Connecticut crabbing had been excellent following another great 2010 year. After the heavy July 2011 rain event, many western crabbers noticed a significant brown coloration to the water. This brown color is linked to the breakdown of oak leaves. Tannin, an acid, is very high in oak leaves. Some reported that the waters also “smelled” badly like sulfur. This hydrogen sulfide smell is attributed to coastal bodies of water and salt marshes in late summer when dissolved oxygen is at its lowest point. Bacterial processes in high heat and low oxygen tends to reduce organic matter (leaves) by bacterial reduction of sulfate releasing the hydrogen sulfide gas – thus the foul or rotten eggs smell. This smell (stink) was prevalent in the later stages of The Great Heat a century ago and noticed by coastal residents near marshes. That also occurs today and many coastal residents can confirm this late summer event. The rainfall may have dislodged rotting leaves increasing levels of hydrogen sulfide in tidal areas. The same areas that had been so productive for blue crabs can lead to high sulfide levels and might trigger these large late summer migrations.

Warm waters and few storms helps the blue crabs habitats but as with the lobsters, great catches are made just before a habitat crash – and the blue crabs in Connecticut might be facing a similar tipping point – an almost forgotten hydrogen sulfide toxicity in the water itself. This is due perhaps to the buildup of black sulfurous mud called Sapropel. In warm weather leaves and organic matter rots and produces Sapropel. It accumulates rapidly with few storms to wash it out it can reach several feet deep – locally it’s called Black Mayonnaise, and is often a dominant habitat type. Not too much is known about the extent of Sapropel deposits in Connecticut. Key scientists worldwide were looking at it just after The Great Heat 1880-1920, and had convened a world conference about sulfurous mud just prior to World War II. The conference (1938) papers were eventually printed in 1958 but by that time we were in the period of cold and numerous storms, the North Atlantic Oscillation. Estuarine habitats had reversed - Sapropel deposits were washed away and from bays, coves and salt ponds, and a new habitat type, estuarine bivalve shell now became dominant. Winter flounder was enhanced by firm bottoms estuarine shell, while blue crabs which need the Sapropel to burrow into during the winter – for long hibernation periods retreated -mostly and today to rivers and dredged channels. The onset of a habitat reversal had “helped” some species increase – up to a point. That seems to be the case with Sapropel, and now perhaps blue crabs.

In a Cape Cod study in the middle 1980s, a diverse habitat type produced the best diversity or biological richness. The observations included one quarter, hard mud, or sand, one quarter estuarine shell, one quarter vegetation, and one quarter small stones (or cobblestones) were the richest habitat areas in terms of biological diversity. When one habitat type dominated total abundance often remained about the same but diversity declined. A dominant habitat type – all yielded some organisms- except Sapropel. This habitat type tended to reduce diversity and in large deposits was vacant of most recognizable animal life forms.

Sapropel did contain eels and eelgrass together; it was felt to be important to habitat requirements of overwintering Blue Crabs who needed to hide from predators during long winter hibernation. It was, however, a limiting habitat type and in large deposits devastating to most shore life, fishers often reported accumulating leaves first - the material that creates Sapropel. Oak and Maple leaves are naturally acidic and in poorly flushed coves and bays collect and rot in summer heat. This is the material that so many kayakers experience (not pleasant and often dangerous) in shallow warm waters. When oxygen levels normally lower in warm water, this organic matter cooks – rots as terrestrial compost- but here the reduction processes create a perfect storm of habitat failings or constituents, sulfuric acid, hydrogen sulfide, ammonium and now removes all oxygen. One long time winter flounder fisher, Louis Bayer, from eastern Connecticut (1980s) watched as his favorite winter flounder habitats were covered with “black mayonnaise” and once commented to me “this stuff is bad for fish” – I quickly agreed, it was.
In some bays Sapropel has past 25% coverage to as high as 50 % to 75%. Previous core studies do show episodic events in coves that have core samples layered then mud with estuarine shell. These habitat reversals could have happened before, many times in Connecticut’s fisheries habitat “history”.

In the late 1970s Sapropel seemed to increase along with Blue Crab increases – There appears to be a habitat connection with older blue crabs which tend to seek out these soft deposits in winter, but in late summer Sapropel becomes deadly. The compost residues from Sapropel has a role in acidification of estuarine soils – bivalve shell erosion, lowering oxygen and in the presence of ammonium which fuels brown algal blooms and hydrogen sulfide a lethal one-two knockout punch to many organisms we as a society value. Sapropel is now linked to the tremendous increase in necrotic fin rot disease in winter flounder populations during the same time, and an increase in the plant nutrient ammonium which favors the harmful brown algal species (HAB). HAB blooms have been shown to reduce bay scallop habitat quality.

As habitat quality for Blue Crabs increased, winter flounder habitat quality declined. Sapropel may even trigger mass movements of Blue Crabs by the presence of hydrogen sulfide levels in the water itself. That movement has happened the past three summers- although the 2011 “waves” were weak following a much colder winter, blue crabs could be moving to avoid hydrogen sulfide toxicity.

The movements of Blue Crabs east can be attributed to several factors but none confirmed. Several explanations exist:

1) The movement west as with lobsters is more suited to larval recruitment and as crabs and lobsters mature, they may become habitat limited – and move east seeking greater space or habitat capacity (some of the densest blue crab sets Megalops have been in the Bridgeport/Fairfield area)

2) Warm summer temperatures drive Blue Crabs out of rivers first from low dissolved oxygen levels and finally toxic hydrogen sulfide (late summer).

3) Blue Crabs and lobsters appear to move toward the morning light, east as mentioned in old fish observation reports – the same is true for Bay Scallops noted to swim east in Long Island Sound before storms.

4) Chemical contamination – possibly from West Nile treatments but the July 2011 die off of blue crabs occurred also during a heavy rain – so freshwater poisoning, chemical contamination, and low dissolved oxygen conditions may have all contributed to this die off (crabs should be tested for residue- my opinion)

5) Hydrogen Sulfide Toxicity – this can happen in late August as rainwater flows become less, and waters warm thus holding less oxygen. In some rivers, up to 50% of flow can be sewage in the summer months. Dense accumulations (greater than 6 inches) of Sapropel shed ammonium and produce hydrogen sulfide in warm weather, therefore a sudden rain can rip into soft Sapropel deposits causing the “black water death” events (fish kills) with fish. These are mentioned by fishermen at the turn of the century. Hydrogen sulfide is highly toxic to most marine organisms and those areas poorly flushed have been known to have high hydrogen sulfide levels. This habitat impacted event associated with Sapropel has been largely missed – but one study conducted by Dr. Art Gaines of the Woods Hole Oceanographic Institution found in the Narrow River lagoons, Rhode Island, sulfide levels 10 times higher than those of the Black Sea. That was in 1975 even before the hot period intensified in the 1990s.

High organic loadings can also interfere with gill respiration collapsing ionic exchanges causing high mortalities. A high rainfall therefore may be the biological trigger for such mass movements of blue crabs from river mouths to the open Sound – into a predator-prey relationship that also deserves further study.

Crabs leaving the protection of brackish waters to full salinity waters asks the question that many crabbers have also asked, realizing the predator relationship and lack of cover (not many offshore eelgrass meadows which is a natural crab habitat type) why does this happen at all? The presence of blackfish (tautog), blue fish and stripers alone are devastating to crabs and the ability to burrow in and hide must be reduced on cobble stone, etc. The answer to the question is they probably don’t choose to move early, they are forced to move early. It looks like the July 2011 blue crab die-off was region wide in western, CT before the mild winter (not most likely winterkill as last March it was in the 70s). A flood of rainwater could have dislodged Sapropel deposits and released with the (smells) tannin (brown color) hydrogen sulfide mortality (visual observations by several Megalops reporters). What we do know from the reports obtained in 2011 that crabbers that had been crabbing 20 years or more had never seen anything like this before. These observations during this weather period are extremely significant and important.

As blue crab catches increased in CT after 1998, crabbers asked why, the levels of catches today are somewhat astounding as to those in the 1950s and 1960s. This year’s blue crab season may answer many of the above questions.

Watch for the Year Class Megalops Divisions – The next few weeks could answer many questions.

The key habitat question is for the juveniles, not so much for the adults. Key to understanding the habitat quality question as it related to blue crabs here in CT is the survival of a now native Megalops set, or the survival of a transported Megalops by currents into Long Island Sound from southern areas or both. The simple blue crab population response is that it got hot, and that is certainly true, but the habitat question is far more complex and directly related to the increase in the Megalops survival rates here in Long Island Sound.
The 2013 blue crab year may answer many important habitat questions, a year following a hurricane and a very cold winter as compared to warm one. What to look for, the 2012 Megalops (2 inches) the 2011 Megalops now 3 to 4 inches and the remains of those incredible 2010 and 2009 Megalops sets the 5 inches and up category.

A good mixture if various size reports – multiple year classes is a positive habitat indicator. Missing “year classes” or unequal size distributions are negative indicators. Two or more year classes “missing” in 2013 signify a habitat failure.

As in previous year’s shellfishers will most likely be the first group to report on surviving blue crabs.

Only the next few weeks will tell.

Email blue crab reports to: tim.visel@new-haven.k12.ct.us
Every observation is valuable as we learn more about our blue crab population.

The Search for Megalops is part of a Project Shellfish/Finfish Student/Citizen ]Monitoring Effort Supported by a 2005 grant to The Sound School from the National Fish and Wildlife Foundation grant #2005-0191-001.
Program reports are available upon request.

For more information about New Haven Environmental Monitoring Initiative or for reports please contact Susan Weber, Sound School Adult Education and Outreach Program Coordinator at susan.weber@new-haven.k12.ct.us
The Sound School is a Regional High School Agriculture Science and Technology Center enrolling students from 23 participating Connecticut communities.