NECAN Industry Webinar Series
The American Lobster in a Changing Ecosystem
December 12, 2018
Rick Wahle, University of Maine, Curt Brown, Ready Seafood Co., and Jesica Waller, Maine Department of Marine Resources
The American lobster has become a poster child for the impacts of environmental change on coastal ecosystems and economies. This talk sets the stage for two in-depth presentations to follow on the effects of warming and acidification on lobster larvae, and an industry perspective on the future of the fishery. Dynamic food webs and climate seem to be changing faster than fishery managers and the industry can adapt. In southern New England elevated summer heat stress, hypoxia and disease have led to widespread collapse of the region’s once thriving lobster fishery. But in the cooler Gulf of Maine ocean warming has reinforced the top-down effects of depleting predatory ground fish, such as Atlantic cod, triggering an unprecedented boom in lobster production, one that has elevated the species to its current status as the most valuable single-species fishery in the US and Canada. The future of this fishery is far from certain. The northward advance of shell disease and southern predators, and changes in the pelagic and benthic food web, pose real threats. And with few alternative fisheries, coastal communities in Maine and Atlantic Canada are now perilously dependent on this single fishery. Traditional single-species fishery stock assessment does not fully capture the drivers of population dynamics, and it is increasingly important to embrace ecosystem-based management and forecasting tools that account for environmental interactions. The iconic lobster therefore has broad relevance as a case study of the sometimes contrasting impacts of environmental change and exploitation on our living marine resources and coastal communities.
Three years ago Ready Seafood began a unique research collaboration with the University of Maine to improve the understanding of how lobster settlement varies by depth along Maine’s coast. After two years of Maine Sea Grant funding, Ready Seafood, a wholesale lobster company based in Portland, Maine, stepped up to fund this project going forward so that this important research could continue. To the best of the company's knowledge, this was the first example of a private company funding public research. This team of scientists, fishermen, and Ready Seafood employees has been hard at work wrapping up this year’s field season and are starting to see some interesting patterns. This industry-science collaboration fills a knowledge gap in the understanding of Maine’s most valuable natural resource and has benefited the business on many fronts.
Despite the commercial importance of the American lobster, Homarus americanus, there has been little research on how changing conditions in the Gulf of Maine will impact lobster growth, development, and reproduction. During this presentation, Jesica will summarize the research she conducted at Bigelow Laboratory for Ocean Sciences and the University of Maine to examine the response of lobster larvae to a predicted end-century pCO2 and temperature. This study highlighted the interactive effects of these two stressors and offered insight into larval development and physiology under these conditions. Jesica will also describe work currently underway at the Maine Department of Marine Resources to quantify changes in the size at maturity of female lobsters over time along the coast of Maine. Finally, Jesica will discuss how warming in the region may be driving these changes and how the results of this work can be incorporated into the stock assessment and future management decisions.
Climate Change Impacts on the Health of Commercially Important Shellfish Species
November 27, 2018
Bassem Allam, Stony Brook University School of Marine and Atmospheric Sciences
Broad and profound ecosystem alterations have been described throughout the globe as a result of modifications in environmental conditions associated with global climate change. Shifts in marine species distribution, including those of economical importance (e.g. shellfish), as well as their microbial pathogens, have been highlighted. In this presentation, a few examples of the impacts of climate alterations on the health of a select number of shellfish species in the Northeastern United States will be described. Inshore populations of the American lobster (Homarus americanus) around the southern range of the species distribution dramatically decreased (e.g. Long Island Sound) and remaining stocks have been suffering from increasing levels of epizootic shell disease (ESD). Our laboratory investigations showed a severe impact of increasing temperatures on lobster immunity and field observations reported potential linkages between ESD prevalence and reduced lobster immune performances. In parallel, the northern range of the most devastating microbial parasites of oysters (Crassostrea virginica) is expanding and this expansion was linked to the warming trends in the region (e.g. Dermo disease caused by Perkinsus marinus). In parallel, changes in precipitation regimes associated with projected climate alterations may cause the loss of disease refugia by lowering salinities in some estuaries below thresholds needed for oyster survival (e.g. the Hudson River). The Atlantic surfclam (Spisula solidissima) is yet another species that has been suffering from increasing temperatures in the region, where significant decline in surfclam abundance was reported in near-shore waters from New York to Virginia. Field observations have demonstrated that surfclams in this area show signs of physiological stress. Our laboratory studies further confirmed the negative impact of ecologically-relevant high temperatures on surfclam scope for growth, reproductive effort, and immune performances. Ocean acidification represents another facet of global change and the negative effect of acidification on the development of calcifying organisms has been showcased in a large number of studies in the last decade. More concerning, our recent investigations highlight pernicious sublethal effects of acidification on shellfish immunity, making these organisms more susceptible to microbial infections. But global climate alterations may also have unexpected benefits as in the case of QPX disease in the hard clam (Mercenaria mercenaria). In this case, our research showed beneficial impacts of warming trends on clam health. Despite this willingly optimistic final note, the predicted future of shellfish resources in the Northeast is worrisome and calls for immediate mitigation actions wherever possible.
Losing their lifeline? Mussel Attachment in a Warmer, Higher CO2 World
October 4, 2018
Emily Carrington, University of Washington
Mussels are well known ecosystem engineers and often dominate and structure wave swept mid-intertidal zones on temperate coasts worldwide. They are also an important aquaculture species and a “biofouling” nuisance to many maritime industries. Mechanical disturbances to mussel populations, such as dislodgment due to a combination of increased flow forces and weakened attachment, therefore have important ecological and economic ramifications. Mussels attach securely to hard substrates such as rock, neighboring mussels, aquaculture rope, and ships by molding individual tethers known as byssal threads. In controlled laboratory experiments, we have found byssal threads weaken under ocean acidification (OA) and ocean warming (OW). Our field observations of farmed mussel populations largely confirm these laboratory observations. Our ecomechanical framework provides a valuable tool for predicting the responses of mussels, and their dependent coastal communities, to current and future climate scenarios.
Emily Carrington is Professor of Biology at the University of Washington. Her research is based at the Friday Harbor Laboratories in the San Juan Islands, where she leads a marine biomechanics research group. For over two decades, she has focused on the mechanical design of marine invertebrates and macroalgae, especially those that thrive in one of the most physically challenging habitats on earth, the wave-swept rocky intertidal zone. She draws upon the fields of engineering, biology, and oceanography to develop a mechanistic understanding of how coastal organisms will fare in changing ocean climates. She is currently serving as a Program Director in the Division of Integrative Organismal Systems at the National Science Foundation in Alexandria, Virginia.
OCA Impacts on Shellfish Hatcheries
September 18, 2018
Alan Barton, Whiskey Creek Shellfish; Bill Mook, Mook Sea Farm; Michael Congrove, Oyster Seed Holdings
Over the past decade, the Pacific Northwest Shellfish Industry has been grappling with the effects of Ocean Acidification on commercial production of Pacific oyster larvae. The region is characterized by strong summertime upwelling, which brings naturally acidic deeper ocean water up onto the Oregon and Washington continental shelf. As such, our region is already ‘on the edge’ of the saturation state threshold required for normal larval shell development. The added impacts of human-induced acidification observed over the past decade pushed our coastal bays over this threshold, leading to devastating seed production failures from 2007-2009. Our industry has made a great deal of progress in understanding, and adapting to OA in recent years, and have restored much of our historic production through coordinated monitoring up and down our coastline along with development of treatment systems in commercial hatcheries. These efforts have not only allowed us to address the direct effects of OA on initial larval shell development, but have greatly improved our understanding of secondary and tertiary factors affecting production, as the advance of OA in our region alters the way our coastal ecosystems function.
In 2009, Mook Sea Farm, an oyster farm and hatchery in Maine, began experiencing larval production problems. These problems included the occasional failure of fertilized eggs to become viable larvae, but more often, prolonged larval durations. Larval production was highly unpredictable. West Coast hatcheries had recently experienced similar larval production problems which were determined to be caused by decreased calcium carbonate saturation states in their incoming water. In contrast to the West Coast, our water’s decreased saturation states resulted from a combination of increased atmospheric CO2 and increased freshwater runoff from heavy precipitation events. Hatchery production was restored to better than pre-2009 levels by buffering all seawater used for larval and juvenile production in the hatchery. We use inexpensive pH meters and controllers to maintain the pH in our hatchery culture systems. Along with increasing atmospheric CO2, precipitation in the Northeast is projected to increase in spring and fall months. While we can control seawater chemistry in the hatchery, many questions remain about the extent to which coastal acidification will affect juvenile and market oyster grow out at our lease site. In 2014, working with Dr. Joe Salisbury of UNH we installed sophisticated seawater monitoring equipment to help us answer some of these questions.
Shellfish aquaculture production has seen a steady rise worldwide for the last 40 years. Integral in this has been the ability to consistently produce vast amounts of shellfish larvae in increasingly sophisticated shellfish hatcheries. The fact that these hatchery’s primary task is culturing a calcifying larval organism, a fraction of a millimeter in ultimate size, make them uniquely susceptible to the effects of ocean acidification and/or coastal acidification. Increasing frequency of unexplained poor larval production has spurred commercial shellfish hatcheries in Virginia to loosely organize around the common goal of better understanding the effects of variable ambient water quality on larval production success. Carbonate chemistry being one, albeit big, piece of the total water quality puzzle. This presentation will explore the water quality puzzle and efforts to solve it, as it pertains to shellfish hatcheries from the perspective of Oyster Seed Holdings, a commercial oyster hatchery located on the western shore of Chesapeake Bay in mesohaline waters.
Coastal Change Impacts
August 9, 2018
Shawna Chamberlin and Hannah Pearson, Island Creek Oysters; Donald "DJ" King, King Lobsters and Montowese Bay Oysters
Shawna Chamberlin and Hannah Pearson
A recent increase in coastal flooding has required consideration for the different ways it could potentially impact hatcheries, from equipment placement (to reduce damage) to water quality parameters. The first flood Island Creek Oysters experienced was a double-edged sword; they were unprepared and there was much more damage within the hatchery, but having seen the weak points they were better prepared to take action prior to the next flood to protect as much of the equipment as possible, as well as pull in water from the bay at an optimal time. They have also become more interested in keeping better track of the water quality parameters to form baseline data so that when something like this happens, they know what the “normal” is. Island Creek Oysters also suffered some damage and gear movement as a result of the ice and storms. In the end it was beneficial to experience this flooding in the current hatchery, so that they might more adequately prepare the new hatchery to stand up to such storms and occurrences.
A graduate of Clark University who studied economics and geography, DJ, (aka Donald King), began lobstering and fishing on Long Island Sound in 1969 at the age of 10. Over time, his career path has also included earning a 50 ton captain’s license, captaining clam and oyster boats, farming oysters and bay scallops, and finally – so far – growing seaweed. He is the owner/operator of King Lobsters and Montowese Bay Oysters. DJ is also an appointed member of the Connecticut Seafood Council. Today, instead of lobster pots in the water, DJ has built a shellfish upweller at his home and is raising bay scallops and oysters in cages on his leased grounds as well as experimented with growing sugar kelp and the red seaweed, Graciliaria.
Sediment Saturation State
July 12, 2018
Jeffrey Clements, Norwegian University of Science and Technology; Brian Beal University of Maine at Machias
Studies in the early 2000's suggested that low saturation state in marine sediments could drive mass mortality of settling bivalves. Since then, a number of sediment acidification effects have been reported, most notably altered behaviour. In this presentation, Dr. Clements will provide an overview of sediment acidification effects on bivalves reported to date, with a strong focus on burrowing behaviour. Dr. Clements will then place these behavioural effects in a more holistic ecological context and lay out key knowledge gaps that need to be addressed.
Soft-shell clam, Mya arenaria, landings in Maine have declined by more than 33% over the past five years, and more than 75% since 1990. The loss of commercial clams has been more severe recently in southern Maine than elsewhere along the coast. For example, towns in northern Casco Bay (e.g., Brunswick, Harpswell, Freeport) have witnessed landing declines of more than 50% since the mid-2000’s. While numerous sources of clam mortality exist to help explain the decline in landings, such as disease, pollution, over-harvesting, and increasing seawater temperatures, two others, predation and ocean/coastal acidification seem to draw most of the attention from scientists and regulators. Studies conducted in northern Casco Bay have shown that seawater and sediments are becoming increasingly acidic, and that in some coves and embayments, shell dissolution of soft-shell clam juveniles is occurring. Therefore, beginning in 2014 and continuing through 2016, a series of both large- and small-scale field experiments was established at three intertidal flats in Freeport, Maine (Staples Cove, Little River, Recompense) to examine methods to mitigate effects of coastal acidification on clam recruitment. Experiments were conducted at these sites after pH sampling revealed these locations to be among the lowest (range = 7.2 to 7.4) of eight commercial flats sampled. Treatments included the addition of aged, crushed shells of Mya (0, 13, or 26 lbs/100ft2 ) to field plots (100ft2 ) that either allowed predators unrestricted access or were protected with netting (4.2 mm aperture; to deter epibenthic predators such as fish, birds, and crabs). A completely randomized design was deployed in late April or May at each site, and each combination of both factors (netting [a = 2 levels]; crushed shell [b = 3 levels]) assigned randomly to plots in a 6 x 5 array (n = 5 replicates for each of the 6 treatments). Experiments lasted until late October or early November in each year. Because crushed shell could act either as a habitat for small crustaceans such as green crabs (Carcinus maenas) or spatial refuge for juvenile clams from large green crab attack, a series of small-scale studies (experimental units = plastic horticultural pots – 6-inches in diameter x 6-inches deep) examined similar treatments with one exception: the addition of a non-buffering habitat (small, granite chips similar in size to the crushed shell) that occurred in both protected and control units. Results showed that clam recruits: 1) responded similarly in both large- and small-scale experiments; 2) were unaffected by the different levels of crushed shell; 3) had significantly higher densities in treatments that were protected from predators; and, 4) were generally larger in protected vs. control plots. In addition, at the end of the study, pH levels in the large-scale plots protected with netting were significantly lower than in unprotected, control plots. These findings suggest that while coastal acidification may act to reduce clam populations in northern Casco Bay, predators are relatively more important in controlling soft-shell clam populations. Shellfish managers should focus their attention on methods to adapt to increasing seawater temperatures that are driving an upsurge in predator populations that have resulted in the precipitous declines in commercial soft-shell clam landings.
Question and Answer Session for Sediment Saturation State Webinar
Moderated by: Meredith White, PhD, Mook Sea Farm and NECAN Industry Working Group Chair