[BlueChip]

The Sound School Inter-District marine Education Program Newsletter
Habitat Information for Fishers and Fishery Area managers
Understanding Science Through History

The Question of a Habitat History for Bay Scallops
Timothy C. Visel, The Sound School
The Rise of Sapropel – The Fall of Bay Scallops 1975 to 2005

Submitted to the EPA – DEEP Long Island Sound Study Committee on Non Point Source Pollution in January 2013
Revised to April 2013

Can We Determine Bay Scallop Abundance from Habitat Histories
Revised for Capstone Proposals – January 2014

IMEP #14 February 2014

This paper is not the viewpoint of the EPA-DEEP Long Island Sound Study Partnership. No consensus has been reached regarding Sapropel or the impacts of a renewed forest canopy upon shallow near coastal habitats. It is the viewpoint of Tim Visel, member of the LISS Habitat Restoration Workgroup and Citizens Advisory Committee but does not represent the position of either. The existence of Sapropel (rotting leaf and terrestrial organic build up) is currently under review. I welcome any comments or exchanges of information. I can be reached at tim.visel@new-haven.k12.ct.us

Introduction

This latest warm period which began in earnest in 1974 came after a strong or negative North Atlantic Oscillation (NAO) during the 1950’s. Before that time a period known in northern New England as the “Hot Term” but those living closer to New York City recall it as “The Great Heat,” a remnant of the 1880 to 1920 of “great” heat waves that struck New England cities. To the poor who lived in poorly ventilated multi story structures in cities then with little centralized sanitation there was nothing great about these heat waves, they killed people by the hundreds. The winters could be cold but the storm track which so typifies a NAO pattern had cold air dropping deep into the Great Lakes region and below which soon became hot in summer. A cooling shore breeze caused by land thermal heating became a welcome relief to people who could escape the aggressive summer heat. At this time many couldn’t afford to move to the shore each summer for these cooling “airs” and transportation routes were unreliable. Steamship and later trains made possible the establishment of many coastal “shore” communities at this time, especially in Connecticut.

While USDA agricultural weather forecasters talked about these hot periods impacting New England farmers - New England fishers also felt the impacts. The North Atlantic Oscillation was strengthening and the prevailing winds became more westerly and drier. This air mass reflected a strengthening Icelandic low which tended to draw circulation across the Great Lakes into New England. But with the dry heat came air mass stability – strong storms around then faded in both intensity and frequency. By the 1890s the Long Island Sound Devils Belt storms of the 1870s were then distant memories. The period 1880-1920 became one of warmth and general shoreline stability – powerful storms were infrequent and winters temperatures were cold but not like the 1870s where temperatures were 20º f below zero and continued for days at a time. It was the extreme summer heat and lack of hurricanes that would come to signify this habitat period and also New England’s fisheries. It was the age of the oyster and blue crab – not bay scallops or lobsters.

Sea Level Rise Slows -

Shorelines were generally stable and many summer resorts were built close to the beach or on it, to capture those cool breezes as what was of value to city dwellers. These businesses would be the first ones wiped out by the weakening of the Icelandic low, which now allowed colder air to sink far south in a huge horseshoe shaped bulge – a giant horseshoe in the central United States. This storm track allowed two things, polar air to sink south into massive cold air breakouts that made it to Florida, and an increase in coastal storms coming up on the east side of the horseshoe as hurricanes with tropical moisture and its winter equivalent, the much feared Northeasters. The climate was changing and a habitat battle was about to begin one mostly out of sight to the general public. It was a battle over habitat capacity and these created in heat and little energy as those who needed cold and storms. The climate and weather patterns on the continent would also impact fisheries – not as short term changes but increasing or decreasing habitat quality from rainfall. Farmers would look to seasons for weather impacts but the moderating impacts of marine habitats were somewhat insulated from extreme temperature fluctuations but not energy. Fishers measured these changes in decades. It took decades for the rise in heat to eliminate much of the bay scallop habitats of the 1870s, but by 1900 they were gone from southern New England.

Climate Change and Fisheries

In the marine realm storms were and continue to be events which highlight the sudden impacts of energy upon the shoreline and sub tidal fish and shellfish habitats they contain. We have a cultural bias (negative) towards the energy events at the coast and the New England Hurricane of 1938 quickly put everyone on notice – things were changing and no one could foretell the energy that awaited shoreline residents in the 1950s and 1960s. This negative NAO would return the lobster and bay scallop but vanquish blue crabs and oysters – a habitat reversal of profound scope and fishers impacts.
Bay Scallops Often Move Before Storms
People were shocked by the devastation of the 1938 hurricane. Coastal damage of that magnitude until then was rare as coastal residents had gotten use to a fairly stable and consistent shorefront but they weren’t to only one to see changes. The morning of the New England 1938 Hurricane fishers started noticing changes also, some hours before it arrived.

The late 1920s had seen a return of much colder winters and an increase in Northeasters. One of the biggest surprises was the return of bay scallops first to the Cape Cod areas but then Rhode Island following the bitter cold winters of 1922 and 1923. By the 1930s the oyster boats at City Point, City Pont Oyster Boats locked in thick ice were often free by shoveling coal on the ice, the coal picked up solar heat and softened the ice shield saving many vessels at this time (George McNeil personal communications, 1988). New Haven would be iced in for weeks but bay scallops had already returned to Niantic Bay. [Bay scallops came to be known as the Christmas crop – not trees but seafood to support seasonal funds just before the holiday especially during the depression years, see similar accounts in George Goode, US Fish Commission Series Vol 2 pg 568 “Referring to the point (storms) Capt S. Pidgeon of Sag. Harbor, says that if possible, when driven before a storm they will work to windward and he has seen them swimming in schools, 10 feet deep.” See part xx The Scallop Fishery pg 565 to 581 – The Fisheries and Fishing Industries of The United States, George Brown Goode Assistant Secretary of the Smithsonian Institution – Section V, Volume II, Washington GOP 1887. ] It was colder and organic matter which tended to collect in warm storm free periods now was washed from coves and bays. Eelgrass which had grown thick during The Great Heat (1880-1920) was ripped out by storms as bottom habitats now changed. A more alkaline red algae assemblage replaced eelgrass as sediments set heavy with bivalves mostly clams as the pH of marine soils reversed – becoming more alkaline. As this change was gradual fishers celebrated the return of bay scallops but colder winters meant irregular oyster sets and blue crabs which once over wintered in Sapropel were killed by the loss of habitat as “winter kill” or cold water starvation now thought to combined with sulfide poisoning. After 1931 strong quahog (mercenaria) sets also returned to northern waters. Some of the largest “Great Sets” occurred in relic oyster beds (shell harsh) after storms washed off sulfide filled organic matter.

The morning of September 21, 1938, John Hammond of Chatham Massachusetts (an oyster planter) recounted that clammers and oysters planters had noticed increased quahog sets but also an increase in hard clam predators mostly conch and starfish but generally higher mortality for oysters. So the return of bay scallops was a welcome Chatham fishery for the fall. Fishers appreciated a new cash crop when soft shells clams were declining just before the holidays. Seed bay scallops were at in all the Cape Cod coves. They had anticipated a good fall crop of bay scallops in 1938. The discussion of the fall soon turned from inside the clam and oyster shops outside to the Oyster Pond River as small patches of bay scallops flapped shells on the outgoing tide heading out to Nantucket Sound, by mid morning these patches grew larger all heading out from the Oyster Pond River. Mr. Hammond recalled that everyone groaned as they watched “Christmas” swim out to sea1. No doubt a survival strategy for leaving shallow water and a few hours later/the fishers were in a survival mode themselves as later the hurricane hit Cape Cod.

It was bay scalloping, however a undependable crop to shellfishers, bay scallops were known for heavy sets, two or three years of good fishing and then nothing, one of the perplexing comments during the 1870s and early 1880s is that bay scallops can swim. Early bay scallopers often reported hearing them at night, “the quick shutting of the shells makes a loud snap which can be heard at a considerable distance” (US Fish Commission Series Vol 2, Section V, 1887 GPO) “and repetitions of this comical maneuver in progression with long rests between, carry it over long distances; and that scallops sometimes do make considerable journeys in large companies is well proved” ibid page 569. The sporadic nature of the harvest is mentioned in many historic reports, along with two factors strong storms and bitter cold winters but the most important factor was temperature. What scallopers were reporting was oscillation energy and temperature changes – they were keen observers and had narrowed the choices following the 1870s New England’s mini ice age and the wide catches even then were perplexing. The coldest and harvest conditions were followed by the best bay scallops crops?

“One year there may be hardly any at all, and the next year a great plenty, I think the severity of the winter temperature has much to do with it. The year 1879 was a poor season, but this season (1880) young scallops are more plenty than ever before known” ibid page 570 (US Fish Commission Reports).

And as the conditions continued to warm past the 1880s and into the 1890s fishers then focused upon habitat conditions but the marine environment in cold and stormy periods I suspect nitrogen was also limiting – so many of the coves were not able to sustain plankton densities to support extremely dense populations of scallops constantly so the bay scallop success was its ability of dispersal into those areas able to support it, (food wise). Bay scallops were perhaps the locusts of the marine environment in small coves. Small macro habitat nutrient levels may impact bay scallop carrying capacity. This seems to be substantiated by numerous comments by fishers that when bay scallops population were high oysters and soft shell clams were nearly always low (habitat carrying capacity). They could move into bays as well as move out, many reports on Cape Cod point to shock or surprise of bay scallops arriving suddenly in the fall, or dismay to see they have all left (sometimes at Pleasant Bay, Orleans, overnight). These types of accounts appear many times in the historical literature – especially movement before storms.

In the 1950s, bay scallop conflicts were common between Orleans and Chatham. One year it involved local police departments when apparently the entire scallop population moved to the Chatham side overnight.
The short life span and large population fluctuations of the bay scallops have also perplexed shellfish biologists for over a century. The problem is a bias into the research process itself, it is likely that such high densities of bay scallops in relatively shallow and semi enclosed bays was not over the long term biologically or fisheries wise sustainable. Immense quantities of Bay Scallops could literally eat themselves out of food, we know from frequent reports the negative impacts of dense eelgrass populations on the size and meat weight of bay scallops. Without good food replenishment by ample circulation of water scallops often starved in eelgrass that is mentioned many times in the historical literature. Bay scallops because of their shortened life cycle needed enormous amounts of carbohydrate rich green algae. The green red and golden algae species is favored by cooler temperatures and available nitrate from the cold reduction of organic matter by oxygen. Experiments were underway at the turn of the century to enhance the algal capacity of seawater by adding nitrogen as it was often limiting in colder water (Riley 1967). Colder waters for New England usually bring more storms and these storms likely had a role in fertilizing local waters by the removal of marine humus or compost. That compost would build up during warm periods and recognizable for habitat changes would now be introduced back into the water column. We know that warm water compost as Sapropel. In high heat and limited oxygen Sapropel would “shed” enormous quantities of ammonia, not nitrate. In 1898 for example a huge fish kill was preceded in Narragansett Bay by reports of “chocolate waters” now suspected to have been the browns (HABS). Harmful algal blooms need quick access to ammonia the byproduct of high heat sulfur reduction of organic deposits. Therefore in long hot periods you see these fish kills and black water deaths related to them.

Habitat Quality for Bay Scallops and Sapropel

Most reports from fishers particularly baymen frequently mention changes in bottom firmness after 1974 in high heat and that is why, it got hot. After a long warm period Sapropel tends to accumulate and nitrogen is “banked” in a huge sink of partially reduced compost. In high heat it putrefies sheds ammonia from a sulfur smelling black jelly-like material. A decrease in temperature would favor the greens algae while long hot periods favor the browns (see HABS). High green, red, and golden populations are supported by high nitrate levels while the browns thrive in high ammonia levels. Sapropel therefore could not provide the fuel for high populations of the bay scallops preferred food (red /green) during a huge habitat quality transition (it was hot). As storms increased and temperatures declined these habitat factors should be considered for the 1950s and 1960s, they “reversed.” Storms did wash Sapropel from coves down to the “black sands.” Many shellfishers on Cape Cod mentioned “black sands” after very severe storms during these shellfish meetings, between 1981-1983.
1) Sapropel in cold water oxygen could now produce enormous amounts of nitrate – in available oxygen, big surges in bay scallops are often reported immediately after bitter cold winters – reds golden and green species – were perhaps available in greater amounts.
2) A gradual shift in densities from the browns to red/greens favored bay scallops during colder periods. As energy levels increased bay scallop abundance often shows that same trend. It goes up over time.
3) In warm periods with little energy, an acidic sulfur rich substrate Sapropel often containing eelgrass replaces an alkaline estuarine shell habitat with red macro algae which is known to containing scallop setting and spawning chemicals (Maerl) in colder storm filled periods. With Sapropel comes a declining habitat quality for bay scallops and abundance/catches go down. (Long term) (USFWS Data).
4) A cooler energy filled period tends to reduce Sapropel deposits and then become nitrogen limiting especially in very cold and storm filled regions. After many years of storms Sapropel deposits are reduced to zero as they are simply washed away. Long Island Sound was thought to be nitrogen limited in the late 1950s – (negative NAO period).
5) When presented with unfavorable habitat conditions including food availability bay scallops can move. Therefore possible explaining historic reports of a sudden arrival or departures mentioned so often by baymen and shellfish biologists (usually at night).
6) Bay scallops are also naturally limited by food availability denser concentrations and may resemble terrestrial locusts that “leave” habitats when food levels drop. Therefore, high consistent bay scallop populations may not be sustainable and competition with other benthic bivalve populations for food should be considered. This is mentioned by fishers as relative abundance differences – “When clams and bay scallops are high quahogs are low”


Summary

In reviewing the period known as The Great Heat (1880-1920) Sapropel and eelgrass meadows greatly increased and bay scallops disappeared. In the 1950s to 1960s Sapropel decreased with eelgrass and New England bay scallop landings soared. This period is known as the North Atlantic (New England) Oscillation. The last warm period 1974 to 2008 (from 2008 onward it appears we are in a habitat transition period very hot to very cold, and a significant increase in energy) is very similar to the 1880 – 1920 period. The 1920s onward as winters became colder and the number of gales increased bay scallops returned to the northern areas first, than Rhode Island and finally Connecticut.

The coldest storm filled period 1950 to 1965 for instance saw the highest Connecticut bay scallops landings. When the warm period began in the 1970s Connecticut lost its bay scallops first, followed by Rhode Island and finally Cape Cod and the Islands, it took two decades for this habitat transition and another decade for a complete habitat reversal. Eelgrass presence may be one of the most important habitat indicators we have of this reversal between estuarine bivalve shell habitats and Sapropel, softer bay bottom habitat types.

Coastal cores taken in Connecticut in the 1990s frequently show this bivalve shell, mud layering. Eelgrass is frequently first in after an energy event and eventually last out in a habitat transition.

The Sapropel/eelgrass habitats should now be considered transitional or sucessional habitats between energy cycles. Bay scallops and oysters populations reverse with failures in habitat quality largely determined by changes in temperature. High bay scallop populations need high nitrate levels in bays and coves to nourish preferred algal foods (Chlorella species – other red, golden, green algae) which may not be sustainable and partially explain large fluctuations in population size. Bay scallops from historical records may move to areas of higher habitat suitability. Long Island Sound Researchers were recording immense golden /green algal populations that would suddenly collapse in the late 1950s – leading some to investigate seasonal nitrogen shortages. At the time the US Fish and Wildlife Service Scientists at Milford (today the NMFS NOAA Laboratory) where investigating Chlorella blooms and in a September 1957 National Geographic Magazine quoted Dr. Loosanoff stating “It’s almost pure Chlorella – an acre of sea water, used to grow this one called algae, could produce for more protein than you can get from an acre of landing even with soy beans (Fossenden Blanchard Long Island Sound (1958) pg 147). At the end of the North Atlantic Oscillation red, golden and green algal blooms were intense in the spring but faded as nitrate levels declined. Chlorella was a nutritious food for bay scallops and needed ample nitrate levels to sustain dense cultures. Bay scallops for example can “starve” trying to live off HABS. Two popular current feeds for bay scallops Monochrysis lutheri and Isochrysis galbana also need high nitrate levels. This points to a temperature aspect of nitrate availability as higher temperatures favors ammonia under low oxygen saturation levels from benthic sediments reduction processes. (Related to the Sulfur cycle) colder temperatures typically show higher nitrate levels. Warmer periods show higher ammonia levels in organic filled habitats (see Meeting House Creek Study on Long Island, New York).

Fishery Statistics Provide Important Habitat Quality Information – The Rhode Island Narragansett Bay Case History – A Similar Habitat History.

After the cold and very stormy 1870s eelgrass was at low levels but bay scallops thrived especially in Narragansett Bay when eelgrass became dominant – bay scallops disappeared – after 1931 eelgrass died off and bay scallops reappeared. In Connecticut during the 1950s Sapropel and eelgrass was washed from Niantic Bay (frequent hurricanes) but bay scallop landings soared, when the late 1970s warmer temperatures and less storm energy Sapropel reappeared with eelgrass and bay scallops died out. It therefore appears bay scallops populations appear to be cyclic and Sapropel research may lead to a significant negative habitat relationship.

Despite much printed information the abundance of eelgrass to bay scallop landings actual data shows a nearly perfect negative habitat association, when eelgrass populations are low historically- bay scallop populations are high. During long hot and energy poor periods Sapropel collects and eelgrass does well and bay scallops do not. Sapropel might be the overlooked critical habitat factor for a bay scallop habitat indicator, part of a larger habitat successional “clock.”

This seems to have already occurred. The Narragansett Bay deep water bay scallop fisheries were immense in the colder and stormy 1870s. With The Great Heat (1880-1920) these habitats changed and the scallop deep water fisheries failed. It was not overfishing or pollution contrary to many published articles. The largest oyster production levels were recorded during periods of immense pollution. Hard clams are most likely the most pollution tolerant of the species. As it presence is linked to declining bay scallop habitat, low pH and sulfide toxicity to bay scallops during warm periods should be reviewed. There is a bias in the current literature to under report or cite historic references to the eelgrass/shellfish habitat interactions.

Its accumulation however may provide the future nitrate supply during colder periods to allow its recovery. Bay scallops and Sapropel may have a direct yet opposite habitat connection. [A description of this deep water bay scallop fishery is available from The Sound School Adult Education and Outreach program titled The Great Heat and the Rhode Island Deep Water Bay Scallop (Argopecten irradians) fishery 1875 to 1905. Available from Susan Weber, susan.weber@new-haven.k12.ct.us. At this time, Rhode Island had its largest bay scallop fishery in deep waters on “beds” that stretched some twenty five miles in a generally north-south direction from Mount Hope Bay south on the east side of Narragansett Bay and on the west south of the Providence River to the Wickford, Quonset Point area. Bay scallops were in waters out to thirty five feet deep. Ernest Ingersoll, writing in Section V of the United States Commission of Fish and Fisheries (1887) described this unique deep water fishery, detailing a hard bottom dredge modified with a “kettle bail” and flat blade dredge which then was termed a “scraper.]

The difference is scallop landings over time indexed for energy levels and temperatures could also be connected to Sapropel in ways we do not yet fully understand.




Capstone Research Questions

The basic question is during this warm period Sapropel has become a dominant habitat type. When it was largely removed by storms in the 1950s and 1960s its presence significantly declined to a corresponding increase in bay scallops, why?
Always willing to share information and comments – Tim Visel can be reached at tim.visel@new-haven.k12.ct.us

Anyone interested in a short review of the Climate Pattern (NAO) North Atlantic Oscillation that directly affects habitat and therefore Connecticut’s shell and fin fisheries see The Search for Megalops-The rise of Blue Crabs Special Report #1, January 2014, available from Sue Weber at susan.weber@new-haven.k12.ct.us or can be obtained or accessed on the Adult Education and Outreach directory by accessing the Sound School website: www.soundschool.com/publications%201.html.
For information about The Sound School website, publications, and / or alumni contacts, please contact Taylor Samuels at taylor.samuels@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.
Program reports are available upon request. For more information about New Haven Environmental Monitoring Initiative for IMEP reports, please contact Susan Weber, The Sound School Adult Education and Outreach Program Coordinator, at susan.weber@new-haven.k12.ct.us.