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Increased atmospheric carbon dioxide (CO2) has led to global climate change and ocean acidification (OA) via the absorption of atmospheric CO2 by the ocean. Coastal shelves are also affected by various processes that influence the acidity of seawater, causing acidity to vary over time and space. These variations in ocean acidity can negatively impact marine species, especially calcifying organisms such as surfclams and sea scallops. In the Mid-Atlantic Bight (MAB), a subsection of the U.S. Northeast Shelf (NES), this variation in acidity generates ecological and economic concerns as the MAB is home to some of the nation’s most productive and profitable estuaries and fisheries. In this study, Rutgers University (southern MAB) and Stony Brook University (northern MAB, Hudson Canyon) deployed two gliders equipped with sensors measur-ing depth, temperature, salinity, pH, dissolved oxygen, and chlorophyll to monitor winter 2021 carbonate chemistry conditions on the shelf as well as in slope waters of the MAB. For both deployments, measured pH and calculated aragonite saturation state (Ωarag) showed opposing patterns, with high pH and low Ωarag in shelf/nearshore and low pH and high Ωarag in slope waters. These trends were attributed to different driving factors whereas pH was more influenced by biological processes (i.e. photo-synthesis) and Ωarag was influenced mostly by thermodynamics and chemical factors (i.e. temperature, total alkalinity). The results of this study underscore the importance of monitoring coastal acidity to understand potential impacts on important species.

Statistical models built using different data sources and methods can exhibit conflicting patterns. We used the northern stock of black sea bass (Centropristis striata) as a case study to assess the impacts of using different fisheries data sources and laboratory‐derived physiological metrics in the development of thermal habitat models for marine fishes. We constructed thermal habitat models using generalized additive models (GAMs) based on various fisheries datasets as input, including the NOAA Northeast Fisheries Science Center (NEFSC) bottom trawl surveys, various inshore fisheries‐independent trawl surveys (state waters), NEFSC fisheries‐dependent observer data, and laboratory‐based physiological metrics. We compared each model's GAM response curve and coupled them to historical ocean conditions in the U.S. Northeast Shelf using bias‐corrected ocean temperature output from a regional ocean model. Thermal habitat models based on shelf‐wide data (NEFSC fisheries‐dependent observer data and fisheries‐independent spring and fall surveys) explained the most variation in black sea bass presence/absence data at ~15% deviance explained. Models based on a narrower range of sampled thermal habitat from inshore survey data in the Northeast Area Monitoring and Assessment Program (NEAMAP) and the geographically isolated Long Island Sound data performed poorly. All models had similar lower thermal limits around 8.5℃, but thermal optima, when present, ranged from 16.7 to 24.8℃. The GAMs could reliably predict habitat from years excluded from model training, but due to strong seasonal temperature fluctuations in the region, could not be used to predict habitat in seasons excluded from training. We conclude that survey data source can greatly impact development and interpretation of thermal habitat models for marine fishes. We suggest that model development be based on data sources that sample the widest range of ocean temperature and physical habitat throughout multiple seasons when possible, and encourage thorough consideration of how data gaps may influence model uncertainty., This study assesses the sensitivity of generalized additive models, frequently used in habitat modeling, to various fisheries data sources used as input by using black sea bass (Centropristis striata) as a case study. Results show that similarities and differences between habitat models can inform uncertainty estimates and can have strong implications for coupled oceanographic habitat models often used to represent spatial habitat distributions for a wide variety of applications.

Summary In the last decade, the ocean has absorbed a quarter of the Earth’s greenhouse gas emissions through the carbon (C) cycle, a naturally occurring process. Aspects of the ocean C cycle are now being incorporated into climate change mitigation and adaptation plans. Currently, too little is known about marine vertebrate C functions for their inclusion in policies. Fortunately, marine vertebrate biology, behavior, and ecology through the lens of C and nutrient cycling and flux is an emerging area of research that is rich in existing data. This review uses literature and trusted data sources to describe marine vertebrate C interactions, provides quantification where possible, and highlights knowledge gaps. Implications of better understanding the integral functions of marine vertebrates in the ocean C cycle include the need for consideration of these functions both in policies on nature-based climate change mitigation and adaptation, and in management of marine vertebrate populations.

Antarctic krill Euphausia superba is a key species in the Southern Ocean, where its habitat is projected to undergo continued warming and increases in pCO2. Experiments during 2 summer field seasons at Palmer Station, Antarctica, investigated the independent and interactive effects of elevated temperature and pCO2 (decreased pH) on feeding, growth, acid-base physiology, metabolic rate, and survival of adult Antarctic krill. Ingestion and clearance rates of chlorophyll were depressed under low pH (7.7) compared to ambient pH (8.1) after a 48 h acclimation period, but this difference disappeared after a 21 d acclimation. Growth rates were negligible and frequently negative, but were significantly more negative at high (3°C, -0.03 mm d-1) compared to ambient temperature (0°C, -0.01 mm d-1) with no effect of pH. Modest elevations in tissue total CO2 and tissue pH were apparent at low pH but were short-lived. Metabolic rate increased with temperature but was suppressed at low pH in smaller but not larger krill. Although effects of elevated temperature and/or decreased pH were mostly sublethal, mortality was higher at high temperature/low pH (58%) compared to ambient temperature/pH or ambient temperature/low pH (>90%). This study identified 3 dominant patterns: (1) shorter-term effects were primarily pH-dependent; (2) krill compensated for lower pH relatively quickly; and (3) longer-term effects on krill growth and survival were strongly driven by temperature with little to no pH effect.

Ocean warming is leading to poleward range shifts for many fish species, and while well described, potential life history phenology differences within fish populations along a gradient from their historic to current distributional range have not been studied. In a rapidly shifting fish population, the Northern stock of black sea bass (Centropristis striata), we investigated spawning phenology and output across the US Northeast Shelf to comprise locations in their historic and more recently occupied range near their northern range boundary. Spawning started later in the northern extreme of our study but also ended earlier, leading to decreased spawning duration from south to north. Spawning phenology was mostly driven by Julian day followed by temperature and latitude. Gonadosomatic index, a proxy for reproductive output, was lower in the northern region, indicating that black sea bass did not compensate for the shorter spawning season there. Hepatosomatic index was lower in the northern regions indicating lower pre-spawning liver energy reserves, potentially leading to lower reproductive output. These results suggest a potential for lower recruitment in the recently occupied range and should be further investigated to predict the impacts of ocean warming and for proactive fisheries management as black sea bass distributional range expands poleward.

24 pages, 2 figures, 1 table, supporting Information https://doi.org/10.1111/brv.12679, Important findings from the second decade of the 21st century on the impact of environmental change on biological processes in the Antarctic were synthesised by 26 international experts. Ten key messages emerged that have stakeholder¿relevance and/or a high impact for the scientific community. They address (i) altered biogeochemical cycles, (ii) ocean acidification, (iii) climate change hotspots, (iv) unexpected dynamism in seabed¿dwelling populations, (v) spatial range shifts, (vi) adaptation and thermal resilience, (vii) sea ice related biological fluctuations, (viii) pollution, (ix) endangered terrestrial endemism and (x) the discovery of unknown habitats. Most Antarctic biotas are exposed to multiple stresses and considered vulnerable to environmental change due to narrow tolerance ranges, rapid change, projected circumpolar impacts, low potential for timely genetic adaptation, and migration barriers. Important ecosystem functions, such as primary production and energy transfer between trophic levels, have already changed, and biodiversity patterns have shifted. A confidence assessment of the degree of `scientific understanding¿ revealed an intermediate level for most of the more detailed sub¿messages, indicating that process¿oriented research has been successful in the past decade. Additional efforts are necessary, however, to achieve the level of robustness in scientific knowledge that is required to inform protection measures of the unique Antarctic terrestrial and marine ecosystems, and their contributions to global biodiversity and ecosystem services, With the funding support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI)

Microplastics (MP) are considered emerging contaminants in the water environment, and there is an interest in understanding their entry into the food web. As a growing body of literature demonstrates the ingestion of MP by zooplankton in controlled laboratory studies, few data are available demonstrating in situ observations of MP in zooplankton. A field survey was performed to collect zooplankton in the highly urbanized Hudson-Raritan estuary. Following washing, sorting by species, and enumeration, three dominant species of copepods (Acartia tonsa, Paracalanus crassirostris and Centropages typicus) were digested. MP were filter concentrated and characterized by size, morphology, and color via microscopy and polymer type by micro-FTIR imaging and/or Raman spectroscopy. MP were observed in all extracts performed on the three copepod species with averages ranging from 0.30 to 0.82 MP individual

Exploitation and degradation of the mysterious layer between the sunlit ocean surface and the abyss jeopardize fish stocks and the climate. Exploitation and degradation of the mysterious layer between the sunlit ocean surface and the abyss jeopardize fish stocks and the climate.

Developing the workforce to meet the needs of the blue economy will require changing undergraduate marine science programs to provide a wider range of skills developed by “doing” rather than just “reading.” Students also need training on how to effectively work in a team, critically analyze data, and be able to clearly communicate key points. With that in mind, we developed a new undergraduate course (called Ocean Observing) focused on conducting research by analyzing data collected and delivered to shore in near real time from the growing global network of ocean observatories. The course structure is based on student teams that use data to develop a range of data products, many of which have been suggested by state and federal agencies as well as from maritime companies. Students can take the Ocean Observing course repeatedly throughout their undergraduate career. A complimentary second entry course (called Oceanography House) was developed to entrain freshmen first-term students into research on their first semester on campus. The Ocean Observing course has increased the number of marine science majors and the overall diversity of the marine science program and resulted in a dramatic increase in the number of independent student theses conducted each year. Over the last 10 years, student data profiles from the course emphasize the importance of conducting research in a public way so students can partake in the “adventure” of research before the outcome is known. To increase the public visibility of these “adventures,” collaborations between departments across the campus have developed nationally broadcast documentaries and outreach materials. Going forward, we seek to build on this success by developing an accelerated Masters of Operational Oceanography and link these undergraduate students with external companies through externships and coordinated research projects.

The coastal waters of the West Antarctic Peninsula (WAP) are associated with large phytoplankton blooms dominated by large (>20 µm) diatoms however, nanoplankton ( a (chl- a ) concentrations, which varied by a factor of 5 over the 20-year time series. There has been a significant positive increase in the seasonally integrated concentration of chl- a over the time series. The dominant phytoplankton were diatoms, with cryptophytes the second most abundant. Mixed flagellates also constituted a significant fraction of the chl- a but showed less inter a nnual variability than diatoms and cryophytes. Peak phytoplankton biomass was observed in summer months, when monthly averaged wind speed was lower than in the fall and autumn. Cryptophytes were most abundant during the summer months (December-January) after the seasonal retreat of sea ice. While diatoms were observed over the full range of observed salinities 32–34.5) as well as over the full range of in situ temperatures (−1.5 to 2.5 °C), the cryptophyte populations were observed in locations with lower salinity 32.5–33.75) and colder water (−1 to 1 °C). Environmental factors that favored a shallower seasonal mixed layer resulted in larger diatom blooms compared to the other phytoplankton taxa. During summer with lower phytoplankton biomass, a larger proportion of the chlorophyll a was associated with cryptophytes. These results demonstrate that continued temperature changes along the West Antarctic Peninsula will result in changes in phytoplankton concentration and community composition, which has significant ramifications for the food web.

Coastal and ocean acidification can alter ocean biogeochemistry, with ecological consequences that may result in economic and cultural losses. Yet few time series and high resolution spatial and temporal measurements exist to track the existence and movement of water low in pH and/or carbonate saturation. Past acidification monitoring efforts have either low spatial resolution (mooring) or high cost and low temporal and spatial resolution (research cruises). We developed the first integrated glider platform and sensor system for sampling pH throughout the water column of the coastal ocean. A deep ISFET (Ion Sensitive Field Effect Transistor)-based pH sensor system was modified and integrated into a Slocum glider, tank tested in natural seawater to determine sensor conditioning time under different scenarios, and validated in situ during deployments in the U.S. Northeast Shelf (NES). Comparative results between glider pH and pH measured spectrophotometrically from discrete seawater samples indicate that the glider pH sensor is capable of accuracy of 0.011 pH units or better for several weeks throughout the water column in the coastal ocean, with a precision of 0.005 pH units or better. Furthermore, simultaneous measurements from multiple sensors on the same glider enabled salinity-based estimates of total alkalinity (AT) and aragonite saturation state (ΩArag). During the Spring 2018 Mid-Atlantic deployment, glider pH and derived AT/ ΩArag data along the cross-shelf transect revealed higher pH and ΩArag associated with the depth of chlorophyll and oxygen maxima and a warmer, saltier water mass. Lowest pH and ΩArag occurred in bottom waters of the middle shelf and slope, and nearshore following a period of heavy precipitation. Biofouling was revealed to be the primary limitation of this sensor during a summer deployment, whereby offsets in pH and AT increased dramatically. Advances in anti-fouling coatings and the ability to routinely clean and swap out sensors can address this challenge. The data presented here demonstrate the ability for gliders to routinely provide high resolution water column data on regional scales that can be applied to acidification monitoring efforts in other coastal regions.

Ocean acidification (OA) describes the progressive decrease in the pH of seawater and other cascading chemical changes resulting from oceanic uptake of atmospheric carbon. These changes can have important implications for marine ecosystems, creating risk for commercial industries, subsistence communities, cultural practices, and recreation. Characterizing the extent of acidification and predicting the ramifications for marine and freshwater resources and ecosystem services are critical to national and international climate mitigation discussions and to local communities that rely on these resources. Based on critical grassroots connections between scientists, stakeholders and decision makers, “Knowledge-to-Action” networks for ocean acidification issues have formed at local, regional and international scales to take action. Here, we review three examples of North American groups elevating the issue of ocean acidification at these three levels. They each focus on developing practicable, implementable steps to mitigate causes, to adapt to unavoidable change, and to build resilience to changing ocean conditions in the marine environment and coastal communities. While these first steps represent critical efforts in protecting ecosystems and economies from the risks posed by ocean acidification, some challenges remain. Sensitivity and risk to OA varies by region, species and ecosystems; priorities for action can vary between multiple and conflicting partners; evidence-based strategies for OA risk mitigation are still in the early stages; and gaps remain between scientific research and actionable decision-maker support products. However, the scaled networks profiled here have proven to be adept at identifying and addressing these barriers to action. In the future, it will be critical to expand funding for food web impact studies and development of decision support tools, and to maintain the connections between scientists and marine resource users to build resilience to ocean acidification impacts.

Over the last decade, ocean temperature in the U.S. Northeast Continental Shelf (U.S. NES) has warmed faster than the global average and is associated with observed distribution changes of the northern stock of black sea bass (Centropristis striata). Mechanistic models based on physiological responses to environmental conditions can improve future habitat suitability projections. We measured maximum, resting metabolic rate, and hypoxia tolerance (Scrit) of the northern adult black sea bass stock to assess performance across the known temperature range of the species. A subset of individuals was held at 30°C for one month (30chronic°C) prior to experiments to test acclimation potential. Absolute aerobic scope (maximum – resting metabolic rate) reached a maximum of 367.21 mgO2 kg−1 hr−1 at 24.4°C while Scrit continued to increase in proportion to resting metabolic rate up to 30°C. The 30chronic°C group had a significant decrease in maximum metabolic rate and absolute aerobic scope but resting metabolic rate or Scrit were not affected. This suggests a decline in performance of oxygen demand processes (e.g. muscle contraction) beyond 24°C despite maintenance of oxygen supply. The Metabolic Index, calculated from Scrit as an estimate of potential aerobic scope, closely matched the measured factorial aerobic scope (maximum / resting metabolic rate) and declined with increasing temperature to a minimum below 3. This may represent a critical value for the species. Temperature in the U.S. NES is projected to increase above 24°C in the southern portion of the northern stock’s range. Therefore, these black sea bass will likely continue to shift north as the ocean continues to warm.

[This corrects the article DOI: 10.1371/journal.pone.0218390.].

Today’s students will be challenged over their professional lifetimes to provide society with 60% more food, 55% more water and 80% more energy for a growing global population forecast to exceed 9 billion by 2050. This can only be realized through scientific understanding that applies emerging technologies to optimize sustained observations and forecasts. It requires a workforce with a variety of skills capable of working together as a team to operate new observing technologies in frontier areas, curate the data flow, and produce forecasts with quantifiable uncertainties appropriate to inform decision makers. They will be faced with real data and imperfect models, and will be required to turn it into actionable information. That data is never perfect, and one must see the sensors and platforms, and understand how they work, to fully understand their limitations. To address these issues, Rutgers University has developed new educational programs focused on conducting research by analyzing authentic data collected and delivered to shore in near real-time from the growing global network of ocean observatories. Here we summarize our undergraduate research track and introduce a Masters of Integrated Ocean Observing based on a series of new courses, a software/QA/QC bootcamp, and research symposia. The students graduating from this program will be prepared to join the blue economy with the skills to operate, analyze, and assess data generated from Ocean Observing Systems in support of scientific research and societal applications.

Coastal and ocean acidification can alter ocean biogeochemistry, with ecological consequences that may result in economic and cultural losses. Yet few time series and high-resolution measurements exist to track the existence and movement of water low in pH and/or carbonate saturation. Past acidification monitoring efforts have either low spatial resolution (mooring) or high cost and low temporal and spatial resolution (research cruises). Therefore, there is a critical need to deploy new, cost-effective technologies that can routinely provide high resolution water column data on regional scales in our coastal ocean. We developed the first integrated glider platform and sensor system for sampling pH in the water column of the coastal ocean. A Deep-Sea ISFET (Ion Sensitive Field Effect Transistor) pH sensor system was modified and integrated into a Slocum G2 glider and tested during a deployment in the Mid-Atlantic Bight. Measurements of pH exhibited a time lag that shifted during the deployment, but shifts were applied to correct pH. Glider pH and spectrophotometric pH measured in discrete water samples were in good agreement for some comparisons but not others, and those offsets were likely the result of delayed or incomplete conditioning (at deployment start) or mismatches due to water sampling techniques. Glider pH data along the cross-shelf transect revealed higher pH associated with the depth of chlorophyll and oxygen maximums and a warmer, saltier water mass. Lower pH occurred in bottom waters of the middle shelf and slope, and nearshore following a period of heavy precipitation. These results demonstrate the application of glider-based acidification monitoring in other coastal regions, providing the foundation of what could become a national acidification monitoring network.

Low-power, internally-recording multi-frequency echo sounders can acquire continuous profiles of echoes throughout the water column over long periods of time, thus providing a low-cost method to study the behavior and abundance of fish and zooplankton in the ocean. Ocean gliders are growing in importance as components of ocean observing systems, extending measurements of physical oceanography beyond those possible with moorings and expensive oceanographic research vessels. Payloads are typically composed of conductivity, temperature and pressure along with optical measures of chlorophyll reflectance and dissolved organics. The small size and low power consumption of such echo sounders now makes it practical to install them in gliders, providing the means to simultaneously measure biological metrics through the water column over extended areas and linking physical properties and primary productivity to higher trophic levels such as zooplankton and fish. We have recently installed single-beam echo-sounders with up to four acoustic frequencies in gliders. The echo-sounder (ASL Environmental Sciences’ AZFP) was designed as an autonomous, moored instrument, and several modifications, mechanical, electronic and software were required to adapt it to installation and operation in gliders. The existing lower-frequency transducers were too large and heavy for the glider; their size was reduced by increasing the beam-width, and the housings were redesigned to reduce weight and improve their profile to reduce drag. The transducer housings are designed to be mounted at an angle on the vehicle body so that they are aimed vertically down during the dive phase. Several modifications were also made to the electronics chassis and shrouds to reduce weight, and the power connection was altered to operate from the vehicle battery rather than its own dedicated supply. Examples of these design alterations will be discussed. The instrument operating software was modified to allow communication and control from the vehicle, although data storage remained in the AZFP itself. In the initial case, a 200 kHz, single-beam echo-sounder was integrated and calibrated in a Slocum Webb electric ocean glider. Calibration and controlled field tests demonstrated reasonable signal-to-noise ratio, allowing for detection of plankton and fishes to greater than 75m range. The noise background was higher than that found when the AZFP is used as an autonomous unit, so improvements to noise isolation in the glider should be able to improve the signal to noise ratio in future. A data analysis workflow was developed that estimates glider position and orientation underwater to correct for depth and range of targets. Trial missions in the eastern Gulf of Mexico traveled over a submerged pipeline and a rocky reef. Acoustic backscatter signals attributed to mid-water plankton layers were co-located with oceanographic features and peaks in chlorophyll. Schools of pelagic and demersal fishes were detected and mapped over charted seafloor features. To date, three multiple frequency versions have been built and integrated into Slocum Webb G2 gliders. Several 3-frequency AZFP (38, 70 and 125 kHz) will be used to assess the spatial and temporal distribution of krill biomass in the Antarctic. Several 4-frequency instruments (125, 200, 455 and 769 kHz) have been built to study whales. A glider with a 3-frequency AZFP (38, 125 and 200 kHz) combination was deployed in Terra Nova Bay (western Ross Sea) and mapped the vertical and horizontal distribution and abundance of zooplankton and pelagic silverfish. Future developments will be aimed at adapting the AZFP to other autonomous vehicles and to reducing the effects of the vehicle’s internal noise environment. Ultimately, this glider-based acoustic technology will pave the way for cost-effective, automated examination of food webs and ecosystems in regions throughout the global ocean.

The estuaries and continental shelf system of the United States Mid-Atlantic are subject to ocean acidification driven by atmospheric CO2, and coastal acidification caused by nearshore and land-sea interactions that include biological, chemical, and physical processes. These processes include freshwater and nutrient input from rivers and groundwater; tidally-driven outwelling of nutrients, inorganic carbon, alkalinity; high productivity and respiration; and hypoxia. Hence, these complex dynamic systems exhibit substantial daily, seasonal, and interannual variability that is not well captured by current acidification research on Mid-Atlantic organisms and ecosystems. We present recommendations for research priorities that target better understanding of the ecological impacts of acidification in the U. S. Mid-Atlantic region. Suggested priorities are: 1) Determining the impact of multiple stressors on our resource species as well as the magnitude of acidification; 2) Filling information gaps on major taxa and regionally important species in different life stages to improve understanding of their response to variable temporal scales and sources of acidification; 3) Improving experimental approaches to incorporate realistic environmental variability and gradients, include interactions with other environmental stressors, increase transferability to other systems or organisms, and evaluate community and ecosystem response; 4) Determining the capacity of important species to acclimate or adapt to changing ocean conditions; 5) Considering multi-disciplinary, ecosystem-level research that examines acidification impacts on biodiversity and biotic interactions; and 6) Connecting potential acidification-induced ecological impacts to ecosystem services and the economy. These recommendations, while developed for the Mid-Atlantic, can be applicable to other regions will help align research towards knowledge of potential larger-scale ecological and economic impacts.

Coastal and ocean acidification has the potential to cause significant environmental and societal impacts. Monitoring carbonate chemistry parameters over spatial and temporal scales is challenging, especially with limited resources. A lack of monitoring data can lead to a limited understanding of real-world conditions. Without such data, robust experimental and model design is challenging, and the identification and understanding of episodic acidification events is nearly impossible. We present considerations for resource managers, academia, and industry professionals who are currently developing acidification monitoring programs in the Mid-Atlantic region. We highlight the following considerations for deliberation: 1) leverage existing infrastructure to include multiple carbonate chemistry parameters as well as other water quality measurements, 2) direct monitoring efforts in subsurface waters rather than limiting monitoring to surface waters, 3) identify the best available sensor technology for long-term, in-situ monitoring, 4) monitor across a salinity gradient to account for the complexity of estuarine, coastal, and ocean environments, and identify potential areas of enhanced vulnerability, 5) increase sampling frequency to capture variability, 6) consider other drivers (e.g., freshwater discharge, nutrients, physiochemical parameters) that may affect acidification, and 7) conduct or continue monitoring in specific ecological and general regions that may have enhanced vulnerability. Through the incorporation of these considerations, individual monitoring programs can more efficiently and effectively leverage resources and build partnerships for a more comprehensive data collection in the region. While these considerations focus on the Mid-Atlantic region), similar strategies can be used to leverage resources in other locations.

Crustacean zooplankton produce dissolved organic matter (DOM) and inorganic nutrients via sloppy feeding, excretion, and fecal pellet leaching. These different mechanisms of the release of metabolic products, however, have never been individually isolated. Our study was designed to determine the relative importance of these different modes on release of dissolved organic carbon (DOC), ammonium (NH4+), and urea from Acartia tonsa calanoid copepods feeding on the diatom Thalassiosira weissflogii. Excretion and sloppy feeding were the dominant modes of DOC production (80 and 20% of total DOC release, respectively) and NH4+ release (93 and 7% of total NH4+ release, respectively). Urea, however, was predominately produced via sloppy feeding and fecal pellet leaching (25% and 62% of total urea release, respectively). Urea contributed 20% of total measured nitrogen (TMN; NH4+ + urea) released from copepods, and constituted 100% of TMN released via fecal pellet leaching, 47% of TMN released via sloppy feeding, and only 3.5% of TMN released via excretion. TMN release was > 100% of copepod body N d− 1, resulting in low DOC:TMN release ratios (4.1 for sloppy feeding, 2.1 for cumulative release of sloppy feeding, excretion, and fecal pellet leaching). Our results suggest that the mechanism of release plays an important role in the amount of different forms of DOM, NH4+, and urea available to bacteria and phytoplankton.

Harmful algal blooms (HABs), including toxic species, have been increasing in frequency, range, and duration over the past several decades. The effect of a harmful or toxic algal diet on zooplankton nutrient regeneration, however, has not been previously examined. In this study, we determined the effects of non-bloom and bloom concentrations of non-toxic and toxic cultures of HAB species Prorocentrum minimum and Karlodinium veneficum on grazing and production of dissolved organic carbon (DOC), nitrogen (DON), and phosphorus (DOP), and inorganic nutrients, ammonium (NH4+) and phosphate (PO43−), by the copepod Acartia tonsa and the heterotrophic dinoflagellate Oxyrrhis marina. Ingestion rates of grazers were significantly higher while feeding on bloom algal concentrations compared to non-bloom algal concentrations, but were always below 1% body C d−1 for A. tonsa (ingestion rate range of 0.5–31 ng C individual−1 d−1) and below 2% body C d−1 for O. marina (range of 0.1–8.8 pg C individual−1 d−1). However, rates of inorganic nutrient and dissolved organic matter (DOM) release, when detected, were always >100% of carbon (C), nitrogen (N), and phosphorus (P) ingested. Additionally, the quantity and forms (organic vs. inorganic) of nutrients released by zooplankton were significantly different between non-toxic and toxic algal treatments, and typically higher grazer DOM release occurred while feeding on toxic algal cultures. DOM was the only detected form of nutrient released from O. marina, and DON and DOP were significant portions of total dissolved N and P released for A. tonsa feeding on toxic K. veneficum (69–84% and 73%, respectively). Low grazing rates on all algal diets used in our study, regardless of cell concentration or toxicity, likely resulted in starvation and subsequent catabolism of grazer body tissue. The potential for additional factors affecting variable grazer nutrient release between toxic and non-toxic algal treatments, including algal nutrient quality and direct toxic effects, are discussed. Our results suggest these grazers may not be capable of controlling bloom formation of these HAB species, and that nutrient cycling dynamics in the coastal ocean may change with increases in the presence of harmful and toxic algal blooms.

The West Antarctic Peninsula (WAP) has experienced significant change over the last 50 years. Using a 24 year spatial time series collected by the Palmer Long Term Ecological Research programme, we assessed long-term patterns in the sea ice, upper mixed layer depth (MLD) and phytoplankton productivity. The number of sea ice days steadily declined from the 1980s until a recent reversal that began in 2008. Results show regional differences between the northern and southern regions sampled during regional ship surveys conducted each austral summer. In the southern WAP, upper ocean MLD has shallowed by a factor of 2. Associated with the shallower mixed layer is enhanced phytoplankton carbon fixation. In the north, significant interannual variability resulted in the mixed layer showing no trended change over time and there was no significant increase in the phytoplankton productivity. Associated with the recent increases in sea ice there has been an increase in the photosynthetic efficiency (chlorophyll a -normalized carbon fixation) in the northern and southern regions of the WAP. We hypothesize the increase in sea ice results in increased micronutrient delivery to the continental shelf which in turn leads to enhanced photosynthetic performance. This article is part of the theme issue ‘The marine system of the West Antarctic Peninsula: status and strategy for progress in a region of rapid change’.

Acartia tonsa copepods are not limited to herbivory and can derive up to half their daily ration from predation on heterotrophic ciliates and dinoflagellates. The effects of an omnivorous diet on nutrient regeneration, however, remain unknown. In this study, we fed A. tonsa an exclusively carnivorous diet of either (1a) heterotrophic dinoflagellate Oxyrrhis marina or (1b) Gyrodinium dom- inans, (2) an exclusively herbivorous diet of Thalassiosira weissflogii diatoms, or (3) a mixed omnivo- rous diet. We measured the release rate, composition, and stoichiometry of dissolved organic carbon (DOC), dissolved organic phosphorus (DOP), and nitrogen (urea) in addition to the inorganic nutri- ents, ammonium (NH4 + ) and phosphate (PO4 3- ). Despite similar ingestion rates among treatments, as well as similar C:N ratios of food items, A. tonsa release rates of DOC and NH4 + were highest while feeding on a carnivorous diet and lowest while feeding omnivorously. In contrast, urea, on average, was a higher portion of total nitrogen released in the mixed diet treatment (32 to 59%). DOP release rates were only detectable in diets containing microzooplankton prey. Our results suggest that cope- pod diet plays an important role in determining the quantity and composition of regenerated C, N, and P available to phytoplankton and bacteria. Additionally, the uncoupling of ingestion and nutrient release rates and the variability in released ratios of dissolved C:N:P in our study suggests that stoi- chiometric models based exclusively on predator and prey C:N and N:P ratios may not be adequate in determining stoichiometry of total nutrient release.

Underwater autonomous gliders have transitioned from exotic experimental systems to becoming a standard platform capable of collecting data over a critical range of spatial and temporal scales in the ocean. The data are proving to be extremely valuable for addressing a wide range of basic and applied research questions. These communities are growing from distributed research and/or education groups. It is crucial as systems continue to evolve that there is an effort to “harmonize” data products while preserving the diversity of approaches/science/experimentation. As the gliders have matured and new battery solutions provide additional energy, there is an increased focus on the integration of a wider range of sensors to be incorporated into gliders. Many of these new classes of sensors will be particularly effective for characterizing biological processes in the coastal ocean. As biological sensors generally provide proxy estimates of a parameter, developing robust quality control and assurance procedures is critical. These new sensors will be more power intensive thus requiring the development of planning tools for increasing energy efficiency during missions. Given the significant growth in the highly distributed glider community, efforts are now focusing on the development mission planning tools to allow for efficient operation of glider fleets. To further collaboration and standardization of the growing number of glider operators we have initiated a series of community efforts called glider paloozas. We had an exceptional turnout last year, encompassing 18 U.S. and Canadian partners, 28 gliders, 36 glider deployments, and spatial coverage from coastal regions of Newfoundland to the Gulf of Mexico and offshore to Bermuda. The coordinated effort focused on several research themes including continental shelf circulation, fish migrations, and storm activity. The main goals of last year's effort were to produce a seamless flow of real-time glider data into the Global Telecommunications System (GTS) via DMAC and into the regional ocean models and demonstrate the potential of a U.S. national glider network. This is in line with the goal to increase glider data accessibility from Federal and Academic oceanographic modeling communities, the U.S. Integrated Ocean Observing System (IOOS), and other federal funding agencies (i.e., NSF). In order to demonstrate the value and necessity of the planned U.S. national glider network and build on last years successes, we hope to continue these efforts and require that all glider data produced by Gliderpalooza 2015 participants be uploaded by the individual operators to the DAC 2.0 and into GTS.

The West Antarctic Peninsula (WAP) is home to large breeding colonies of the ice-dependent Antarctic Adélie penguin (Pygoscelis adeliae). Although the entire inner continental shelf is highly productive, with abundant phytoplankton and krill populations, penguin colonies are distributed heterogeneously along the WAP (Ducklow et al., 2013, in this issue). This ecological conundrum targets a long-standing question of interest: what environmental factors structure the locations of Adélie penguin "hot spots" throughout the WAP? - See more at: http://tos.org/oceanography/archive/26-3_schofield.html#sthash.KsdW5rk4.dpuf

Understanding the mechanisms by which climate variability affects multiple trophic levels in food webs is essential for determining ecosystem responses to climate change. Here we use over two decades of data collected by the Palmer Long Term Ecological Research program (PAL-LTER) to determine how large-scale climate and local physical forcing affect phytoplankton, zooplankton and an apex predator along the West Antarctic Peninsula (WAP). We show that positive anomalies in chlorophyll-a (chl-a) at Palmer Station, occurring every 4-6 years, are constrained by physical processes in the preceding winter/spring and a negative phase of the Southern Annular Mode (SAM). Favorable conditions for phytoplankton included increased winter ice extent and duration, reduced spring/summer winds, and increased water column stability via enhanced salinity-driven density gradients. Years of positive chl-a anomalies are associated with the initiation of a robust krill cohort the following summer, which is evident in Adelie penguin diets, thus demonstrating tight trophic coupling. Projected climate change in this region may have a significant, negative impact on phytoplankton biomass, krill recruitment and upper trophic level predators in this coastal Antarctic ecosystem.

Rapidly sinking fecal pellets are an important component of the vertical flux of particulate organic matter (POM) from the surface to the ocean's interior; however, few studies have examined the role fish play in this export. We determined abundance, size, prey composition, particulate organic carbon/nitrogen (POC/PON), and sinking rates of fecal pellets produced by a forage fish, likely the northern anchovy, in the Santa Barbara Channel. Pellet abundance ranged from 0.1-5.9 pellets m(-3). POC and PON contents averaged 21.7 µg C pellet(-1) and 2.7 µg N pellet(-1). The sinking rate averaged 787 m d(-1); thus pellets produced at the surface would reach the benthos (~500 m) in1 day. Estimated downward flux of fish fecal POC reached a maximum of 251 mg C m(-2) d(-1). This is equal to or exceeds previous measurements of sediment trap POM flux, and thus may transport significant amounts of repackaged surface material to depth.

During the summer of 2011 a large phytoplankton bloom occurred off the New Jersey coast, which was monitored using an existing ocean observatory. There was public concern about the root causes of the phytoplankton bloom and whether it reflected anthropogenic loading of nutrients from the Hudson River or whether it reflected coastal upwelling. We used the MARACOOS network to determine what were the likely drivers of the phytoplankton bloom. The bloom was studied using satellites, HF radar, a Hydroid REMUS and Webb Slocum gliders. Chlorophyll concentrations were over an order of magnitude larger than the decadal mean of ocean color data and the bloom was initiated by upwelling winds throughout the month of July that continued to dominate the wind patterns until the passage of Hurricane Irene. The high concentrations of phytoplankton resulted in the supersaturated oxygen values in the surface waters; however the flux of organic matter resulted in oxygen saturation values of

Publisher Summary This chapter focuses on the important role that zooplankton play in nitrogen cycling by following the path of the food from ingestion to all aspects and stages of metabolism. It begins with a discussion of N consumption, including the nitrogenous composition of available food types, rates of N consumption, and effects of food quality. The various aspects of N metabolism, emphasizing the importance to biogeochemical cycling and coupling with other major elements (carbon, phosphorus) are also discussed. Considerable progress in our understanding of the role of marine zooplankton in nitrogen cycling has been made in the last two decades. Studies are now at the stage where large data sets are being compiled, and it is possible, for example, to reasonably predict ammonia excretion as a function of body mass for a given organism and temperature using regression equations—and avoid doing experimental incubations. These individual, size-specific excretion rates can be scaled up to a community rate if total biomass and size structure of the community is known. A common theme throughout this review is that more information is needed on the role of marine protozoa, gelatinous zooplankton, and of taxa living below the euphotic zone in N consumption and metabolism. Consumption of phytoplankton and bacteria by microzooplankton are key processes in N transformations in the ocean.

Ocean acidification has a wide-ranging potential for impacting the physiology and metabolism of zooplankton. Sufficiently elevated CO(2) concentrations can alter internal acid-base balance, compromising homeostatic regulation and disrupting internal systems ranging from oxygen transport to ion balance. We assessed feeding and nutrient excretion rates in natural populations of the keystone species Euphausia superba (Antarctic krill) by conducting a CO(2) perturbation experiment at ambient and elevated atmospheric CO(2) levels in January 2011 along the West Antarctic Peninsula (WAP). Under elevated CO(2) conditions (∼672 ppm), ingestion rates of krill averaged 78 µg C individual(-1) d(-1) and were 3.5 times higher than krill ingestion rates at ambient, present day CO(2) concentrations. Additionally, rates of ammonium, phosphate, and dissolved organic carbon (DOC) excretion by krill were 1.5, 1.5, and 3.0 times higher, respectively, in the high CO(2) treatment than at ambient CO(2) concentrations. Excretion of urea, however, was ∼17% lower in the high CO(2) treatment, suggesting differences in catabolic processes of krill between treatments. Activities of key metabolic enzymes, malate dehydrogenase (MDH) and lactate dehydrogenase (LDH), were consistently higher in the high CO(2) treatment. The observed shifts in metabolism are consistent with increased physiological costs associated with regulating internal acid-base equilibria. This represents an additional stress that may hamper growth and reproduction, which would negatively impact an already declining krill population along the WAP.

Fishes are the dominant vertebrates in the ocean, yet we know little of their contribution to carbon export flux at regional to global scales. We synthesize the existing information on fish-based carbon flux in coastal and pelagic waters, identify gaps and challenges in measuring this flux and approaches to address them, and recommend research priorities. Based on our synthesis of passive (fecal pellet sinking) and active (migratory) flux of fishes, we estimated that fishes contribute an average (± standard deviation) of about 16.1% (± 13%) to total carbon flux out of the euphotic zone. Using the mean value of model-generated global carbon flux estimates, this equates to an annual flux of 1.5 ± 1.2 Pg C yr−1. High variability in estimations of the fish-based contribution to total carbon flux among previous field studies and reported here highlight significant methodological variations and observational gaps in our present knowledge. Community-adopted methodological standards, improved and more frequent measurements of biomass and passive and active fluxes of fishes, and stronger linkages between observations and models will decrease uncertainty, increase our confidence in the estimation of fish-based carbon flux, and enable identification of controlling factors to account for spatial and temporal variability. Better constraints on this key component of the biological pump will provide a baseline for understanding how ongoing climate change and harvest will affect the role fishes play in carbon flux.

Underwater autonomous gliders have transitioned from exotic experimental systems to becoming a standard platform capable of collecting data over a critical range of spatial and temporal scales in the ocean. The data are proving to be extremely valuable for addressing a wide range of basic and applied research questions. This evolution has led to a growing international community of glider laboratories and offers the potential of increased opportunities to leverage efforts across this “young” growing community. To that end, we review the evolution of the glider communities and share our opinions of opportunities and hurdles. These communities grew from distributed research and/or education groups. It is crucial as systems continue to evolve that there is an effort to “harmonize” data products while preserving the diversity of approaches/science/experimentation. As the gliders have matured and new battery solutions provide additional energy, there is an increased focus on the integration of a wider range of sensors to be incorporated into gliders. Many of these new classes of sensors will be particularly effective for characterizing biological processes in the coastal ocean. As biological sensors generally provide proxy estimates of a parameter, developing robust quality control and assurance procedures is critical. These new sensors will be more power intensive, thus requiring the development of planning tools for increasing energy efficiency during missions. Given the significant growth in the highly distributed glider community, efforts are now focusing on the development mission planning tools to allow for efficient operation of glider fleets.

Mitigating and adapting to climate change while the global human population continues its projected growth will be the dominant choice challenge confronting the present generation of undergraduates over their professional lifetimes. Today's students should be prepared to develop solutions that will involve the sea, but life-changing at-sea research experiences for undergraduates are limited. The rapid expansion of ocean observatories provides a solution. We have demonstrated in our own observatory how undergraduate student research can be enabled as a year-round activity during a student's full undergraduate career starting on day 1. What began as the Challenger Glider Mission has spread to other observatory technology and science activities both locally and in remote polar regions.