Monday, February 10, 2014

2014 Connecticut Blue Crab Special Report #2

From Tim Visel at The Search for Megalops:
The Sound School – The ISSP and Capstone Project Proposal
     Building a Network of Citizen Monitors
The Connecticut Blue Crab Population
Habitat Study 2010-2015
  You Do Not Need To Be A Scientist To Report!
The Search for Megalops - The Sound School
Items of Interest to Blue Crabbers
The Search for Megalops Special Program Report #2-2014
February 2014
Habitat Questions about Sapropel, Blue Crabs and Climate Change
Marine habitat succession happens underwater as well
Winter Sulfide levels can kill- Fish and Blue crabs
Some of the problems about marine habitat succession are that it is both long term and happens out of sight.  It is also an area that is under studied and rarely presented to fishery managers or fishers for that matter.  I planned a small habitat succession experiment on land in my backyard to illustrate this point.  Two years ago this spring I purposely stopped mowing (read application of energy) a small section of our backyard lawn.  Many neighbors cut and mow their lawns on a schedule that rivals any transportation routine and apply fertilizer (which I do not) so my experiment with the loss of energy soon became a concern to a neighbor last year who offered to cut down this habitat experiment twice.  But I explained that my lawn mower was a “miniature hurricane” and that the loss of energy quickly caused land habitat succession to be very visible (which it was) but the loss of energy in the marine environment on sub tidal habitats is hard to understand and see.  He seemed puzzled and left shaking his head. 
All summer long small trees spouted, and weeds grew tall and a couple of times he would discuss it looking at it as he mow his lawn to a fine level of smoothness only to see a patch of golden rod and young black locust trees sprout amid wild plants blooming a few feet away.  Again the offer was made this spring to cut down this “wild tangle” but again I declined.  It’s quite noticeable now, I agreed but wanted some pictures – “It will be gone by Christmas,” he seemed okay with that.  That was the point --habitat succession on land was quite noticeable and that in just two years it was something that people could see.  Marine habitat succession of sub tidal areas is hard to see and takes much longer than land.  And when marine succession occurs it’s mostly plants and shellfish that define the habitat quality change and you can see them also as catches but succession in marine habitat types is even more difficult.  That it can take decades.  In sub tidal areas important habitat indicators is of the bottom itself, which is even more difficult to ascertain.  Most of the cove and bay bottoms in Connecticut the last two decades have become softer and often muck filled. It is often referred to as a negative habitat change from fishers.  The soft eelgrass Sapropel bottoms are damaging to winter flounder and shellfish in high heat but do seem to improve blue crabs habitat quality.  Additional research is needed for habitat quality of soft Sapropel bottoms however that would require additional funds. 
There is just not a lot of grant money available for “muck studies” it just doesn’t cry out for research priorities.  Sadly, although Sapropel formation might be the best indicator we have for climate change for Long Island Sound and apparently it has been almost completely overlooked.  But marine habitat succession has profound ramifications for coastal life today especially the history of it, the temperature and energy conditions related to it, impacts to navigation, shoreline erosion, estuarine ecology, habitat quality and finally fisheries abundance.  Most recently those areas do have a responsive research community post Irene and Sandy, but when it comes to marine habitat succession we largely missed the boat. That ship set sail in the late 1970s and with it a negative “NAO” as climate pattern that is also frequently “overlooked” (Megalops report # 1, January 2014).
Bottom sediment quality is so elusive, because it is difficult to see compared to land habitat succession.  That is what is of interest now is we had a second Great Heat (1974 to 2008); since 2008 the temperatures have dropped and energy levels significantly increased for New England thanks for a negative NAO – the North Atlantic Oscillation.  The NAO after being positive for so long turned sharply negative in 2011.  A negative NAO is associated with increased storm activity and cold polar air sinking for south into the middle US. (Megalops Special Report #1, March 26, 2013)
At the beginning of the last century The Great Heat 1880-1920 lobster populations crashed and blue crabs increased.  After 1984 blue crabs started to increase and lobsters crashed again.  In 1931 the climate and energy levels reversed and lead to the cooler and stormier 1950s and 1960s.  Could 2011 have been our 1931?  It is still early to say that but one of the indicators could be climate in the 1920s, blue crab populations began to drop, a series of colder winters was thought to have ruined the blue crab habitat quality, Megalops sets then came too late for blue crabs to survive increasingly long winters but the stormy weather improved conditions for kelp forests and lobsters slowly recovered.  The bay scallops who became practically extinct from southern New England waters in 1920s had reproduction success—improve and  “came back” sometimes suddenly to the amazement and delight of coastal fishers who rejoiced to see an old friend return, it had been a long time.  The NAO turned sharply negative in 1950 – it was the age of the bay scallop and quahog.  Oysters declined to level not seen since the 1870s.  But something also occurred:  bottoms released sulfides stored during long hot periods killing fish and blue crabs in winter.  Sometimes habitat succession is not liked by us when it happens and winter “kills” became common in the 1950s (Megalops Program Report #1, April 17, 2013). Winter kills became common after 1930 in coastal salt ponds.
Habitat Succession Turns Violent 1931 to 1950
To coastal property owners however the 1950s and 1960s there was nothing to rejoice about, while bay scallop production would rise to historic production highs in Niantic, many coastal residents there were busy repairing seawalls, and supported new federal efforts at “flood and erosion control “with local” boards now forming in many municipalities.  The Northeast Atlantic Oscillation appears to be a natural cycle event and it had turned sharply negative.  It is not a new climate event-- the “Polar Vortex” has been mentioned recently in some weather forecasts, but the vortex is a feature of the North Atlantic Oscillation (NAO) but does not directly cause it.  Its presence has been known for quite awhile.  In a book titled “Climate Change,” Harlow Sharpley, Editor (Harvard University Press), Hurd C. Willett describes the “circumpolar vortex” on page 56 and reviews its presence, but it’s quickly recognized today by its large horseshoe shape storm track across the middle United States, drought often on the left side while increased rain or snow on the right – our side of this horse shoe shape storm track.
“The Cycle is one of alternate expansion and construction of the circumpolar vortex with equator ward or pole ward displacement of the prevailing storm tracks.   Periods of expansion of the circumpolar vortex tend to be cool in middle latitudes, accompanied by increased rainfall in lower middle latitudes and decreased rainfall in the highest latitudes.”  Periods of contraction of the circumpolar vortex are marked by warm characteristics particularly in the higher latitude.”  (1953)
First impacted water bodies then were shallow and often had restricted flushing – tidal restrictions.  As such they had increased residence periods for nitrogen locked up in organic matter – compost.  As energy levels decreased (storm intensity/frequently) it built up and then rotted.  In the absence of oxygen, bacteria thrived, consuming organic matter while releasing hydrogen sulfide gas.  When that happened, bay bottoms turned black.  Coastal residents a century ago watched this also happen and they did one of the few things they could do restore the energy and this was accomplished on a limited scale – coastal dredging by horse drawn scoops.
The previous period of warmth 1880-1920 saw bay bottoms turn soft and black.  Oyster sets were huge, blue crabs became abundant.  Black mayonnaise more aptly termed “fresh Sapropel” grew thick creating deep deposits. After 1931, temperatures dropped and storm intensity increased. The built up Sapropel deposits were washed from coves and bays and with it the byproduct of high heat low oxygen reduction by bacteria, sulfides.  At times sulfides could and did kill fish especially under thick ice. These events became known as winter kill.
In the 1940s, ice returned to New England’s salt ponds; duck hunters who enjoyed “open” winters before now saw conditions become colder.  Thick ice formed on salt ponds, in areas of tidal flow winter ice scour increased re-suspending these Sapropel deposits and with it sulfide fish kills, termed black water deaths.  (*Black water is rarely used today although some old aquarium texts still mention it). Sulfide is extremely toxic to fish, effectively blocking oxygen exchange in the gill tissue itself, it binds so completely that even in the presence of oxygen, and fish perish quickly.  Fish simply cannot access the oxygen and flee.  In the transition years, winter fish kills on Cape Cod increased along with colder temperatures came a sudden increase in storm frequency and storm intensity.  Coastal coves with shallow narrow connections to the sea often became blocked with ice and subject to winter sulfide kills.  Coves can also become blocked by storms and coastal residents a century ago would use oxen and horse teams to unblock them. They would do this because this habitat succession threatened valuable herring/alewife runs, seine fisheries and shellfish.
A fish kill (striped bass) happened a few weeks ago in the Black Hall River in the Old Lyme; The Black Hall had been one of the areas that had overwintering blue crabs survive and the past three years one of the first areas to report blue crab catches.  No doubt a thin layer of Black mayonnaise in oxygen helps blue crabs, but deep layers contain high amounts of sulfide and can kill blue crabs as well as fish.  One of the signals of declining habitat quality for blue crabs is the reports of such winter kills.  (Megalops Program Report #1, April 17, 2013).
The buildup of Sapropel (black mayonnaise) has happened here before and a few accounts have survived a local habitat history that describes hard bottom habitat transitions to soft ones.
One of these accounts describes Quiambaug Cove in Stonington. Edgar P. Farnell wrote to me in June 1987 as part of an investigation of increasing Sapropel (Black Mayonnaise) in Quiambaug Cove, Stonington and comments by eastern CT winter flounder fishers.  I was working for the University of Connecticut at the time. Winter flounder fishers reported that heavy muck was now covering once productive winter flounder habitats and those changes had occurred after 1974 when the Negative NAO turned positive to warming temperatures in bringing Southern New England.  This increasing warm temperatures naturally lowered oxygen levels and small coves were some of the first impacted water bodies; they were shallow and often had restricted flushing- tidal restrictions. As such, they had increased residence periods for nitrogen locked in organic matter – compost mostly leaves.  As energy levels decreased (storm intensity/frequency) and temperature increased this created natural anoxic conditions. Organic matter accumulated quickly and then rotted forming Sapropel.  In the absence of oxygen bacterial reduction process, sulfate reducing bacteria thrives, continuing consuming organic matter while releasing hydrogen sulfide gas.  When that happened, bay bottoms turned black.  Coastal residents a century ago watched this also happen and they did one of the few things they could do – restore the energy to increase flushing and this was accomplished on a limited scale, by dredging – salt pond and cove inlets.
The letter that Mr. Farnell wrote to me encompasses those features of coastal salt ponds a century ago is included below,
Dear Mr. Visel:
Mr. Frank Rich has advised me that you are considering improving the tidal flow in Quiambaug Cove.
The buildup of much and heavy vegetation is more of a concern. It certainly has had an effect on the Cove as a whole including clams, oysters, crabs, fish and mussels. When the Filter Plant was built many years ago, the north end of the Cove increased the buildup of heavy mud that has continued for many years.
When my father (deceased 1972) was young, he recalled that every spring landowners along the cove would use a team of oxen and plow to dredge the Cove every year between the bridges at a perigee tide. This, no doubt, improved the tidal flow, because when I was a boy, the Cove had little of the muck which now prevails.
I thought my Father’s recollection might be of help in validating your forecast that dredging the area between the bridges would have a dramatic effect on the quality of sea life within the Cove.
Very truly yours,
Edgar P. Farnell
(June 30, 1987)
In cold weather as ice built up frequently cold water sulfide kills happened naturally and there was nothing coastal land owners could do except wait for spring.  They didn’t like this habitat succession and sought to correct tidal exchange problems themselves and therefore the recent public policy dilemma over climate changes – how much is “us” and how much is “natural.” 
Did a stormy colder period follow a relatively warm period (1880-1920) as coastal storms then were few as compared to the storm filled 1950s and 1960s?  What were the habitat conditions, did they succeed like terrestrial ones, or could hurricanes in the marine environment be the equivalent of land forest fires and quicken habitat succession?  It is natural to see blue crab populations and lobster populations reverse in our area subject to changes in temperature and energy levels, and if so how many times before could such decreases in some species provide clues for another? 
These are some of the questions that come up with a long term environmental fisheries history review that places Mother Nature, with equal footing (a legal term would say standing) as to our involvement?  Is it over fishing or a declining habitat quality?  Is shoreline erosion something we should just expect during negative NAOS.  This is a huge issue for the environmental community, coastal landowners, fishers and the public.  This is why the habitat questions remain, the oyster industry grew to an enormous size during The Great Heat (1880-1920) during a time of an unprecedented period of coastal pollution?  The Connecticut Lobster fishery failed after pollution controls amid excellent conservation and resource management laws.  At the turn of the century (1900), bay scallops collapsed in southern New England but in 1876 Greenwich, CT would have the largest bay scallop fishery – during this brutal cold and stormy period.  In 1876 most of New England ports would be locked in heavy ice by December, but bay scallop fisheries in 1878, two years later would be huge?  Blue crabs were extremely scarce in 1878, but Noank, Connecticut became New England’s lobster capital, and four decades later only to be the site of a lobster hatchery to help replenish small lobsters for a failed lobster fishery but was now the site of now a growing blue crab fishery?  These events are recorded in the fishery statistics for our region.
These species all appear to reverse – In conjunction with habitat quality either being reduced or rebuilt by the negative or positive phases of the North Atlantic Oscillation (NAO). The NAO is one of the most studied and recognized climate patterns in the world.
If you follow the negative and positive phases of the NAO, years later you mirror catches of fish and shellfish. A positive NAO warm few storms certain species thrive, a negative NAO, cold and stormy, the same could be said for other species.
This spring could be the difference for blue crab habitat quality – another long cool spring could mean a late Megalops set – again. This would be the second negative NAO winter in a row for blue crabs.
In the 1950s and 1960s two or three cold springs was often reflected in decreased catches of blue crabs. We might be seeing the first habitat succession changes now in a long cyclic process.  These changes could improve lobster habitat quality years from now.
The species to watch --adult lobsters returning to western  Long Island Sound better  winter flounder recruitment in eastern Connecticut and bay scallops increasing to our north.  That would signal a possible habitat reversal.  The climate pattern to watch is the NAO – a sharp negative phase coincided with a steep drop in blue crab populations in southern New England 50 years ago. A habitat succession process that soon favored lobsters not blue crabs; it could happen again.  Reports of winter kill blue crabs would be important after the ice leaves in a few weeks.
Email your blue crab reports to:
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
The Sound School is a Regional High School Agriculture Science and Technology Center enrolling students from 23 participating Connecticut communities.

No comments:

Post a Comment