A. J. Pershing

• Director of Climate Science at Climate Central

Baleen whales migrate from productive high-latitude feeding grounds to usually oligotrophic tropical and subtropical reproductive winter grounds, translocating limiting nutrients across ecosystem boundaries in their bodies. Here, we estimate the latitudinal movement of nutrients through carcasses, placentas, and urea for four species of baleen whal...

Understanding how rising global air and sea surface temperatures (SSTs) influence tropical cyclone intensities is crucial for assessing current and future storm risks. Using observations, climate models, and potential intensity theory, this study introduces a novel rapid attribution framework that quantifies the impact of historically-warming North...

Ocean temperatures are rising and hit record levels around the world in 2023. While trends are clear and likely strongly connected to human-caused climate change, the oceans also exhibit variability on the daily level, leading to local extremes such as marine heatwaves. We present an operational system to estimate the impact of human-caused climate...

Marine heatwaves, increasingly frequent, impact marine ecosystems and services. Still, understanding how temperature affects observed responses remains limited due to complex interactions among temperature, abiotic and biotic factors, and community dynamics. Here we try to fill this gap by exposing simulated plankton communities to seasonal heatwav...

Marine heatwaves, increasingly frequent, impact marine ecosystems and services. Still, understanding how temperature affects observed responses remains limited due to complex interactions among temperature, abiotic and biotic factors, and community dynamics. Here we try to ll this gap by exposing simulated plankton communities to seasonal heatwaves...

Ocean waters of the Northeast US continental shelf have warmed rapidly in recent years, with sea surface temperatures rising 2.5 times faster than those of the global oceans. With this strong warming trend, the frequency and duration of marine heatwaves have increased. These temperature changes stood out as a distinct warm temperature regime during...

Oceanographic changes are occurring more rapidly in recent decades, with new implications for ocean ecosystems and adjacent human communities. It is important to bring attention to these changes while they are unfolding rather than after they have occurred. Here we report on a rapid shift toward colder, fresher water in the deep Gulf of Maine that,...

Plankton community structure changes seasonally in response to the annual cycles of stratification, temperature, and primary productivity. These communities also change from year-to-year, in some cases exhibiting persistent regime shifts. How changes in physical conditions structure the plankton community and why conditions persist is a fundamental...

Anthropogenic warming is altering species abundance, distribution, physiology, and more. How changes observed at the species level alter emergent community properties is an active and urgent area of research. Trait‐based ecology and regime shift theory provide complementary ways to understand climate change impacts on communities, but these two bod...

Rights-based fisheries management – a management system that apportions harvesting rights of fisheries resources to individuals or groups of individuals based on pre-determined allocation criteria – has become more common in the past three decades due to its potential to achieve resource sustainability while improving economic efficiency. Policies...

The great whales (baleen and sperm whales), through their massive size and wide distribution, influence ecosystem and carbon dynamics. Whales directly store carbon in their biomass and contribute to carbon export through sinking carcasses. Whale excreta may stimulate phytoplankton growth and capture atmospheric CO2; such indirect pathways represent...

Unlike atmospheric weather forecasting, ocean forecasting is often reflexive; for many applications, the forecast and its dissemination can change the outcome, and is in this way, a part of the system. Reflexivity has implications for several ocean forecasting applications, such as fisheries management, endangered species management, toxic and inva...

The Gulf of Maine has recently experienced its warmest 5-year period (2015–2020) in the instrumental record. This warming was associated with a decline in the signature subarctic zooplankton species, Calanus finmarchicus. The temperature changes have also led to impacts on commercial species such as Atlantic cod (Gadus morhua) and American lobster...

The northeastern North American continental shelf from Cape Hatteras to the Scotian Shelf is a region of globally extreme positive trends in sea surface temperature (SST). Here, a 33-year (1982–2014) time series of daily satellite SST data was used to quantify and map spatial patterns in SST trends and phenology over this shelf. Strongest trends ar...

Marine plankton communities can be viewed in terms of their size structure rather than taxonomic composition, revealing how allometric relationships affect the functioning of the community. Oceanic particle size spectra can be used to explain and predict variability in carbon export efficiency, because larger particles generally sink faster than sm...

Studies documenting distributional shifts of fishes typically rely on time series of annual sampling events with fixed seasonal timing and limited temporal range. Meanwhile, as temperatures along the Northeast continental shelf have increased, the seasonal cycle also shifted towards earlier spring warming and longer summers. Seasonal migrations of...

Atlantic salmon is a highly migratory species that has experienced severe population declines. High mortality during the post-smolt period, when fish are migrating from rivers to their open-ocean wintering grounds, may be limiting population recovery, but little is known about this life stage. We used an individual-based model to evaluate the poten...

Extreme and large-scale warming events in the ocean have been dubbed marine heatwaves, and these have been documented in both the Northern and Southern Hemispheres. This paper examines the intensity, duration and frequency of positive sea surface temperature anomalies in the North Atlantic and North Pacific Oceans over the period 1950-2014 using an...

We describe a unique survey method that is able to cover a wide spatial and temporal range at a low cost. We utilised 10 individual small fishing vessels (lobster vessels) as acoustic research platforms to systematically survey a coastal population of Atlantic herring (Clupea harengus) in the Gulf of Maine. We examined 38 transects spanning more th...

Several studies have documented fish populations changing in response to long-term warming. Over the past decade, sea surface temperatures in the Gulf of Maine increased faster than 99% of the global ocean. The warming, which was related to a northward shift in the Gulf Stream and to changes in the Atlantic Multidecadal Oscillation and Pacific Deca...

Considered one of the most endangered cetacean species, the North Atlantic right whale Eubalaena glacialis suffered declining abundance during the 1990s due to a high rate of anthropogenic-associated mortality and a low rate of reproduction. Previous studies have suggested that the reproductive rate is tightly coupled to the abundance of Calanus fi...

Zooplankton fecal pellet flux is a highly variable component of the biological carbon pump. While fecal pellets can comprise 0 to nearly 100% of particulate organic carbon collected in sediment traps, mechanisms for this variability remain poorly understood. Fecal pellet carbon flux is a complex function of several variables. We present a model tha...

Preserving larger fish is often advocated as a conservation measure to help fish populations buffer environmental variation and fishing pressure. The rationale is that several size- and age-dependent reproductive traits confer a higher reproductive value to larger fish. The effects of variation in these reproductive traits on the dynamics of popula...

Understanding marine regime shifts is important not only for ecology but also for developing marine management that assures the provision of ecosystem services to humanity. While regime shift theory is well developed, there is still no common understanding on drivers, mechanisms and characteristic of abrupt changes in real marine ecosystems. Based...

In ecosystems that are strongly structured by predation, reducing top predator abundance can alter several lower trophic levels-a process known as a trophic cascade. A persistent trophic cascade also fits the definition of a regime shift. Such 'trophic cascade regime shifts' have been reported in a few pelagic marine systems-notably the Black Sea,...

Large marine predators such as tunas and sharks play an important role structuring marine food webs. Their future populations depend on the environmental conditions they encounter across life history stages and the level of human exploitation. Standard predator–prey relationships suggest favorable conditions (high prey abundance) should result in s...

Baleen and sperm whales, known collectively as the great whales, include the largest animals in the history of life on Earth. With high metabolic demands and large populations, whales probably had a strong influence on marine ecosystems before the advent of industrial whaling: as consumers of fish and invertebrates; as prey to other large-bodied pr...

Conditions in the oceans change from day-to-day and year-to-year, and these changes impact the distribution and abundance of fish. Fishermen must grapple with these changes on a daily basis, and they are now confronting conditions outside their historical experience. There is a critical need to provide forecasts of fish distributions in space and t...

Understanding how oceanographic factors independently and interactively influence fish behavior, physiology, and survival is essential for predicting the impact of climate change on fish. Such predictions are especially challenging for highly migratory species such as salmon that experience a broad range of conditions. We applied a novel modeling a...

Record, N. R., Pershing, A. J. and Maps, F. 2014. Plankton post-paradox: reply to comment on “The paradox of the ‘paradox of the plankton’” by Record et al. – ICES Journal of Marine Science, 71: 296–298. Classical theoretical ecology has largely focused on the coexistence of populations at the species level, particularly since the coining of the “p...

Dormancy (diapause) is a key life-history strategy of pelagic copepods that allows them to thrive in highly seasonal environments. Successful dormancy of copepodid stages requires the ability to store energy efficiently (for example as lipids) and to slow down the rate of mobilization of this capital during the dormant period. The physiology of lip...

Ostensibly separate fisheries are often linked through ecological, environmental, and human mediated processes that can impact their productivity, profitability, and resilience; however, managers rarely explicitly account for these linkages. We present a coupled bioeconomic model of the American lobster (Homarus americanus) and Atlantic herring (Cl...

North American Atlantic salmon (Salmo salar) populations experienced substantial declines in the early 1990s, and many populations have persisted at low abundances into recent years. Abundance and productivity declined in a coherent manner across major regions of North America, and this coherence points towards a potential shift in marine survivors...

Time series of physical and biological properties of the ocean are a valuable resource for developing models for ecological forecasting and ecosystem-based management. Both the physics of the oceans and organisms living in it can exhibit nonlinear dynamics. We describe the development of a nonlinear model that predicts the abundance of the importan...

Climate change became real for many Americans in 2012 when a record heat wave affected much of the United States, and Superstorm Sandy pounded the Northeast. At the same time, a less visible heat wave was occurring over a large portion of the Northwest Atlantic Ocean. Like the heat wave on land, the ocean heat wave affected coastal ecosystems and e...

Decadal-scale regime shifts in Northwest Atlantic shelf ecosystems can be remotely forced by climate-associated atmosphere-ocean interactions in the North Atlantic and Arctic Ocean Basins. This remote climate forcing is mediated primarily by basin- and hemispheric-scale changes in ocean circulation. We review and synthesize results from process-ori...

Changes in marine plankton communities driven by environmental variability impact the marine food web and global biogeochemical cycles of carbon and other elements. To predict and assess these community shifts and their consequences, ecologists are increasingly investigating how the functional traits of plankton determine their relative fitness alo...

Record, N. R., Pershing, A. J., and Maps, F. 2014. The paradox of the “paradox of the plankton”. – ICES Journal of Marine Science, 71: 236–240. One of the central orienting questions in biodiversity theory and ecology is the “paradox of the plankton”, which asks how it is possible for many species to coexist on limited resources given the tendency...

Maps, F., Pershing, A. J., and Record, N. R. 2012. A generalized approach for simulating growth and development in diverse marine copepod species. – ICES Journal of Marine Science, 69: 370–379. Predicting ecological changes under climate change requires mechanistic descriptions of the impact of environmental conditions on the physiology, life histo...

During recent decades, historically unprecedented changes have been observed in the Arctic as climate warming has increased precipitation, river discharge, and glacial as well as sea ice melting. Additionally, shifts in the Arctic’s atmospheric pressure field have altered surface winds, ocean circulation, and freshwater storage in the Beaufort Gyre...

Time series of American lobster (Homarus americanus) postlarval settlement from southern New England to Atlantic Canada exhibit many common features, and a cluster analysis indicates a block of regions extending from Massachusetts to Maine that have coherent interannual variations. The spatial scale of this block suggests that variability in settle...

Dynamics in fishery ecosystems are forced by natural interactions between species, oceanographic processes, and human activity through fishing. We use a dynamical modeling approach to explore linkages between American lobster, Atlantic herring, and Atlantic cod populations in the Gulf of Maine. An initial model of the natural system demonstrates si...

With few exceptions, fisheries are managed independently, ignoring complex natural and human linkages among them. The American lobster and Atlantic herring fisheries in the Gulf of Maine are subject to human mediated linkages not currently considered in management decisions. Herring is the main bait used by the lobster fishery and presently, the lo...

North American Atlantic salmon (Salmo salar) populations experienced substantial declines in the late 1980s and early 1990s, and many populations have persisted at low abundances. The coherence of declines among populations from Maine to Quebec suggests a shift in marine survivorship, rather than the influence of river-specific factors. While the p...

Small pelagic fish such as herring and sardines are a critical ecological link between changes in oceanographic conditions, including plankton abundance, and populations of larger predators, such as commercial fish, marine mammals, and seabirds. Under an ecosystem-based approach, managing commercial fisheries for small pelagic fish requires balanci...

Atlantic salmon (Salmo salar) spawning returns to rivers continue to decline despite intensive restoration programs. Most management and research efforts have focused on freshwater life-stages and conservation of freshwater habitat. Little is known about the marine phase of post-smolts but recent work suggests a potential bottleneck at this life-st...

Primary sources of mortality and serious injury to endangered North Atlantic right whales Eubalaena glacialis are vessel strikes and entanglement in fishing gear. All management plans depend on knowing when and where right whales are likely to be present. We tested the feasibility of a system designed to predict potential right whale habitat on a w...

A major goal of modern ecology is to understand macroecological patterns based on their mechanistic underpinnings. The metabolic theory of ecology predicts a monotonic increase of biodiversity with temperature based on the principles of metabolism. For marine copepods, observations have shown that while biodiversity does increase with temperature,...

Calanus finmarchicus relies on dormancy to thrive in the seasonal environment of the boreal Atlantic. The lipid accumulation window (LAW) hypothesis proposes that a seasonal window of environmental conditions allows developing individuals to store enough lipids for dormancy to be safely initiated. Successful dormancy requires a sufficient amount of...

Naturally occurring oil slicks are commonly visible in coastal waters. These slicks are suitable proxies for fuel oil spills. We took advantage of these naturally occurring slicks by developing a low-cost system to measure these features and monitor their movement. The use of low-cost digital cameras and a mapping program produces georectified anim...

Studies relating biodiversity to ecosystem processes typically do not take into account changes in biodiversity through time. Marine systems are highly dynamic, with biodiversity changing at diel, seasonal and inter-decadal timescales. We exam- ined the dynamics of biodiversity in the Gulf of Maine pelagic zooplankton com- munity. Taxonomic data ca...

Continuous plankton recorders (CPRs) have been used in the Northwest Atlantic for almost 50 years. While data collected by these surveys have provided valuable information on long-term variability in plankton populations, all previous analyses have been limited to only a portion of the geographic range of the available data. Here we present an anal...

Humans have reduced the abundance of many large marine vertebrates, including whales, large fish, and sharks, to only a small percentage of their pre-exploitation levels. Industrial fishing and whaling also tended to preferentially harvest the largest species and largest individuals within a population. We consider the consequences of removing thes...

Background/Question/Methods The ability to accurately predict the presence of highly migratory marine animals would help to identify unknown habitat, guide survey effort, and assess the impact of proposed conservation actions. North Atlantic right whales (Eubalaena glacialis) migrate 2000+ km, from their calving grounds along the southeast coast...

The validity of computational models is always in doubt. Skill assessment and validation are typically done by demonstrating that output is in agreement with empirical data. We test this approach by using a genetic algorithm to parameterize a biological–physical coupled copepod population dynamics computation. The model is applied to Cape Cod Bay,...

We put forward a combined observing and modeling strategy for evaluating effects of environmental forcing on the dynamics of spatially structured cod populations spawning in the western Gulf of Maine. Recent work indicates at least two genetically differentiated complexes in this region: a late spring spawning, coastal population centered in Ipswic...

Plankton are the main food source in the majority of marine ecosystems and have a crucial role in climate change through primary production and the export of carbon to the deep ocean. Understanding how ocean biology and biogeochemical cycles contribute and respond to climate and other global change is a major challenge of high significance for the...

Background/Question/Methods North Atlantic right whales (Eubalaena glacialis) are critically endangered, 350-400 individuals remain. Collisions with vessels and entanglement in fishing gear are among the primary threats to the continued existence of the species. Knowledge of when and where right whales are likely to be is needed for effective miti...

Ocean observing systems and satellites routinely collect a wealth of information on physical conditions in the ocean. With few exceptions, such as chlorophyll concentrations, information on biological properties is harder to measure autonomously. Here, we present a system to produce estimates of the distribution and abundance of the copepod Calanus...

Management plans to reduce human-caused deaths of North Atlantic right whales Eubalaena glacialis depend, in part, on knowing when and where right whales are likely to be found. Local environmental conditions that influence movements of feeding right whales, such as ultra- dense copepod patches, are unpredictable and ephemeral. We examined the util...

Balancing human uses of the marine environment with the recovery of protected species requires accurate information on when and where species of interest are likely to be present. Here, we describe a system that can produce useful estimates of right whale Eubalaena glacialis presence and abundance on their feeding grounds in the Gulf of Maine. The...

To investigate environmental variability during the late Holocene in the western Gulf of Maine, USA, we collected a 142-year-old living bivalve (Arctica islandica) in 2004, and three fossil A. islandica shells of the Medieval Warm Period (MWP) and late MWP / Little Ice Age (LIA) period (corrected 14CAMS = 1030 ± 78 ad; 1320 ± 45 ad; 1357 ± 40 ad) i...

Arctic climate change from the Paleocene epoch to the present is reconstructed with the objective of assessing its recent and future impacts on the ecology of the North Atlantic. A recurring theme in Earth's paleoclimate record is the importance of the Arctic atmosphere, ocean, and cryosphere in regulating global climate on a variety of spatial and...

Energy variables, such as evapotranspiration, temperature, and productivity explain significant variation in the diversity of many groups of terrestrial plants and animals at local to global scales. Although the ocean represents the largest continuous habitat on earth with a vast spectrum of primary productivity and species richness, little is know...

Numerical diffusion along the age/stage axis is recognized as a significant problem in the modeling of zooplankton populations in dynamic physical environments. We demonstrate the utility of borrowing schemes from numerical fluid dynamics to address this problem. In particular, we use the monotonic upstream scheme for conservation laws (MUSCL) to m...

Changes in Arctic climate have contributed to shifts in abundances and seasonal cycles of a variety of species in the northwest Atlantic.

Cetacean–habitat modeling, although still in the early stages of development, represents a potentially powerful tool for predicting cetacean distributions and understanding the ecological processes determining these distributions. Marine ecosystems vary temporally on diel to decadal scales and spatially on scales from several meters to 1000s of kil...

Cetacean–habitat modeling, although still in the early stages of development, represents a potentially powerful tool for predicting cetacean distributions and understanding the ecological processes determining these distributions. Marine ecosystems vary temporally on diel to decadal scales and spatially on scales from several meters to 1000s of kil...

Pershing, A. J., Greene, C. H., Jossi, J. W., O'Brien, L., Brodziak, J. K. T., and Bailey, B. A. 2005. Interdecadal variability in the Gulf of Maine zooplankton community, with poten- tial impacts on fish recruitment. e ICES Journal of Marine Science, 62: 1511e1523. We used principal component analysis (PCA) to explore interannual changes in a time...

Variations in zooplankton populations in regions throughout the North Atlantic have been tied to changes in the Atlantic atmosphere-ocean system. Recent work has tended to focus on the impact on zooplankton of one particular climate mode, the NAO. However, it is important to remember that the NAO is only one measure of climatic conditions in this r...

With the end of commercial whaling, it was thought that populations of the highly endangered North Atlantic right whale (Eubalaena glacialis) would gradually recover. However, recent modeling studies have shown that the population's growth rate increased gradually during the 1980s, but began declining in the early 1990s, when female mortality rates...

The demographic responses of long-lived endangered species to climate variability can be complex. Nonlinearities in physical and biological processes can obscure relationships between changes in climate and corresponding demo- graphic responses. Efforts to conserve such species will require an understanding of the multi-tiered mechanisms link- ing...

At interannual to multidecadal time scales, much of the oceanographic and climatic variability in the North Atlantic Ocean can be associated with the North Atlantic Oscillation (NAO). While evidence suggests that there is a relationship between the NAO and zooplankton dynamics in the North Atlantic Ocean, the phytoplankton response to NAO-induced c...

Populations of the copepod species Calanus finmarchicus often dominate the springtime biomass and secondary production of shelf ecosystems throughout the North Atlantic Ocean. Recently, it has been hypothesised that interannual to interdecadal fluctuations observed in such populations are driven primarily by climate-associated changes in ocean circ...

A large single-year reversal in the phase of the North Atlantic Oscillation (NAO) during 1996 led to a dramatic shift in the slope-water circulation patterns of the north-west (NW) Atlantic. Analyses of time-series data collected from the region over the past half century show that both physical and biological responses are commonly elicited by suc...

A strong association is documented between variability of the North Atlantic Oscillation (NAO) and changes in various trophic levels of the marine ecosystems of the North Atlantic. Examples are presented for phytoplankton, zooplankton, benthos, fish, marine diseases, whales and seabirds. NAO variability is shown to influence abundance, biomass, dis...

Two surveys were conducted in the well-mixed region of Georges Bank to look for secondary vertical circulation cells, the first in 1996 and the second in 1997. Each survey collected high-frequency acoustic, temperature, and fluorescence data along a 1-n.mile square grid. Concurrent ADCP measurements also were made in the second year. MOCNESS and pu...

Situated in an oceanographic transition zone, the Gulf of Maine~Western Scotian Shelf (GOM/WSS) region of the Northwest Atlantic is especially susceptible to changes in the climate system. Recent studies have shown that a cou- pled slope water system (CSWS) operates in the Northwest Atlantic and responds in a similar manner to climatic forc- ing ov...

The North Atlantic Oscillation (NAO) is associated with decadal-scale forcing of climate and physical oceanography throughout the North Atlantic. Oceanographers have recently established correlations between the NAO and various processes at work in the shelf ecosystems of the NE Atlantic, correlations that have led them to suggest several hypothese...

Results are described from the first field study with the D-BAD MOCNESS (Dual-Beam Acoustics Deployed on a Multiple Opening/Closing Net and Environmental Sensing System), an instrument designed to collect acoustic data and net samples simultaneously from the same portion of the water column. Our primary objective was to evaluate the advantages and...