Kavanaugh Maria T.

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Kavanaugh

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Maria T.

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Satellite remote sensing and the Marine Biodiversity Observation Network: current science and future steps

(Oceanography Society, 2021-11-09) Kavanaugh, Maria T. ; Bell, Tom W. ; Catlett, Dylan ; Cimino, Megan A. ; Doney, Scott C. ; Klajbor, Willem ; Messie, Monique ; Montes, Enrique ; Muller-Karger, Frank E. ; Otis, Daniel ; Santora, Jarrod A ; Schroeder, Isaac D. ; Trinanes, Joaquin ; Siegel, David A.

Coastal ecosystems are rapidly changing due to human-caused global warming, rising sea level, changing circulation patterns, sea ice loss, and acidification that in turn alter the productivity and composition of marine biological communities. In addition, regional pressures associated with growing human populations and economies result in changes in infrastructure, land use, and other development; greater extraction of fisheries and other natural resources; alteration of benthic seascapes; increased pollution; and eutrophication. Understanding biodiversity is fundamental to assessing and managing human activities that sustain ecosystem health and services and mitigate humankind’s indiscretions. Remote-sensing observations provide rapid and synoptic data for assessing biophysical interactions at multiple spatial and temporal scales and thus are useful for monitoring biodiversity in critical coastal zones. However, many challenges remain because of complex bio-optical signals, poor signal retrieval, and suboptimal algorithms. Here, we highlight four approaches in remote sensing that complement the Marine Biodiversity Observation Network (MBON). MBON observations help quantify plankton community composition, foundation species, and unique species habitat relationships, as well as inform species distribution models. In concert with in situ observations across multiple platforms, these efforts contribute to monitoring biodiversity changes in complex coastal regions by providing oceanographic context, contributing to algorithm and indicator development, and creating linkages between long-term ecological studies, the next generations of satellite sensors, and marine ecosystem management.
Hierarchical and dynamic seascapes : a quantitative framework for scaling pelagic biogeochemistry and ecology

( 2013-10-07) Kavanaugh, Maria T. ; Hales, Burke ; Saraceno, Martin ; Spitz, Yvette H. ; White, Angelicque E. ; Letelier, Ricardo M.

Comparative analyses of oceanic ecosystems require an objective framework to define coherent study regions and scale the patterns and processes observed within them. We applied the hierarchical patch mosaic paradigm of landscape ecology to the study of the seasonal variability of the North Pacific to facilitate comparative analysis between pelagic ecosystems and provide spatiotemporal context for Eulerian time-series studies. Using 13-year climatologies of sea surface temperature (SST), photosynthetically active radiation (PAR), and chlorophyll a (chl-a), we classified seascapes in environmental space that were monthly-resolved, dynamic and nested in space and time. To test the assumption that seascapes represent coherent regions with unique biogeochemical function and to determine the hierarchical scale that best characterized variance in biogeochemical parameters, independent data sets were analyzed across seascapes using analysis of variance (ANOVA), nested-ANOVA and multiple linear regression (MLR) analyses. We also compared the classification efficiency (as defined by the ANOVA F-statistic) of resultant dynamic seascapes to a commonly-used static classification system. Variance of nutrients and net primary productivity (NPP) were well characterized in the first two levels of hierarchy of eight seascapes nested within three superseascapes (R2 = 0.5-0.7). Dynamic boundaries at this level resulted in a nearly 2-fold increase in classification efficiency over static boundaries. MLR analyses revealed differential forcing on pCO2 across seascapes and hierarchical levels and a 33 % reduction in mean model error with increased partitioning (from 18.5 μatm to 12.0 μatm pCO2). Importantly, the empirical influence of seasonality was minor across seascapes at all hierarchical levels, suggesting that seascape partitioning minimizes the effect of non-hydrographic variables. As part of the emerging field of pelagic seascape ecology, this effort provides an improved means of monitoring and comparing oceanographic biophysical dynamics and an objective, quantitative basis by which to scale data from local experiments and observations to regional and global biogeochemical cycles.
Observational needs supporting marine ecosystems modeling and forecasting: from the global ocean to regional and coastal systems

(Frontiers Media, 2019-10-15) Capotondi, Antonietta ; Jacox, Michael ; Bowler, Chris ; Kavanaugh, Maria T. ; Lehodey, Patrick ; Barrie, Daniel ; Brodie, Stephanie ; Chaffron, Samuel ; Cheng, Wei ; Dias, Daniela F. ; Eveillard, Damien ; Guidi, Lionel ; Iudicone, Daniele ; Lovenduski, Nicole S. ; Nye, Janet A. ; Ortiz, Ivonne ; Pirhalla, Douglas ; Pozo Buil, Mercedes ; Saba, Vincent S. ; Sheridan, Scott ; Siedlecki, Samantha A. ; Subramanian, Aneesh C. ; de Vargas, Colomban ; Di Lorenzo, Emanuele ; Doney, Scott C. ; Hermann, Albert J. ; Joyce, Terrence M. ; Merrifield, Mark ; Miller, Arthur J. ; Not, Fabrice ; Pesant, Stephane

Many coastal areas host rich marine ecosystems and are also centers of economic activities, including fishing, shipping and recreation. Due to the socioeconomic and ecological importance of these areas, predicting relevant indicators of the ecosystem state on sub-seasonal to interannual timescales is gaining increasing attention. Depending on the application, forecasts may be sought for variables and indicators spanning physics (e.g., sea level, temperature, currents), chemistry (e.g., nutrients, oxygen, pH), and biology (from viruses to top predators). Many components of the marine ecosystem are known to be influenced by leading modes of climate variability, which provide a physical basis for predictability. However, prediction capabilities remain limited by the lack of a clear understanding of the physical and biological processes involved, as well as by insufficient observations for forecast initialization and verification. The situation is further complicated by the influence of climate change on ocean conditions along coastal areas, including sea level rise, increased stratification, and shoaling of oxygen minimum zones. Observations are thus vital to all aspects of marine forecasting: statistical and/or dynamical model development, forecast initialization, and forecast validation, each of which has different observational requirements, which may be also specific to the study region. Here, we use examples from United States (U.S.) coastal applications to identify and describe the key requirements for an observational network that is needed to facilitate improved process understanding, as well as for sustaining operational ecosystem forecasting. We also describe new holistic observational approaches, e.g., approaches based on acoustics, inspired by Tara Oceans or by landscape ecology, which have the potential to support and expand ecosystem modeling and forecasting activities by bridging global and local observations.
Seascapes as a new vernacular for pelagic ocean monitoring, management and conservation

(Oxford University Press, 2016-07-18) Kavanaugh, Maria T. ; Oliver, Matthew J. ; Chavez, Francisco P. ; Letelier, Ricardo M. ; Muller-Karger, Frank E. ; Doney, Scott C.

For terrestrial and marine benthic ecologists, landscape ecology provides a framework to address issues of complexity, patchiness, and scale—providing theory and context for ecosystem based management in a changing climate. Marine pelagic ecosystems are likewise changing in response to warming, changing chemistry, and resource exploitation. However, unlike spatial landscapes that migrate slowly with time, pelagic seascapes are embedded in a turbulent, advective ocean. Adaptations from landscape ecology to marine pelagic ecosystem management must consider the nature and scale of biophysical interactions associated with organisms ranging from microbes to whales, a hierarchical organization shaped by physical processes, and our limited capacity to observe and monitor these phenomena across global oceans. High frequency, multiscale, and synoptic characterization of the 4-D variability of seascapes are now available through improved classification methods, a maturing array of satellite remote sensing products, advances in autonomous sampling of multiple levels of biological complexity, and emergence of observational networks. Merging of oceanographic and ecological paradigms will be necessary to observe, manage, and conserve species embedded in a dynamic seascape mosaic, where the boundaries, extent, and location of features change with time.
Capturing coastal water clarity variability with Landsat 8

(Elsevier, 2019-05-23) Luis, Kelly M.A. ; Rheuban, Jennie E. ; Kavanaugh, Maria T. ; Glover, David M. ; Wei, Jianwei ; Lee, Zhongping ; Doney, Scott C.

Coastal water clarity varies at high temporal and spatial scales due to weather, climate, and human activity along coastlines. Systematic observations are crucial to assessing the impact of water clarity change on aquatic habitats. In this study, Secchi disk depths (ZSD) from Boston Harbor, Buzzards Bay, Cape Cod Bay, and Narragansett Bay water quality monitoring organizations were compiled to validate ZSD derived from Landsat 8 (L8) imagery, and to generate high spatial resolution ZSD maps. From 58 L8 images, acceptable agreement was found between in situ and L8 ZSD in Buzzards Bay (N = 42, RMSE = 0.96 m, MAPD = 28%), Cape Cod Bay (N = 11, RMSE = 0.62 m, MAPD = 10%), and Narragansett Bay (N = 8, RMSE = 0.59 m, MAPD = 26%). This work demonstrates the value of merging in situ ZSD with high spatial resolution remote sensing estimates for improved coastal water quality monitoring.
Modeling phytoplankton blooms and inorganic carbon responses to sea-ice variability in the West Antarctic Peninsula

(American Geophysical Union, 2021-04-01) Schultz, Cristina ; Doney, Scott C. ; Hauck, Judith ; Kavanaugh, Maria T. ; Schofield, Oscar M. E.

The ocean coastal-shelf-slope ecosystem west of the Antarctic Peninsula (WAP) is a biologically productive region that could potentially act as a large sink of atmospheric carbon dioxide. The duration of the sea-ice season in the WAP shows large interannual variability. However, quantifying the mechanisms by which sea ice impacts biological productivity and surface dissolved inorganic carbon (DIC) remains a challenge due to the lack of data early in the phytoplankton growth season. In this study, we implemented a circulation, sea-ice, and biogeochemistry model (MITgcm-REcoM2) to study the effect of sea ice on phytoplankton blooms and surface DIC. Results were compared with satellite sea-ice and ocean color, and research ship surveys from the Palmer Long-Term Ecological Research (LTER) program. The simulations suggest that the annual sea-ice cycle has an important role in the seasonal DIC drawdown. In years of early sea-ice retreat, there is a longer growth season leading to larger seasonally integrated net primary production (NPP). Part of the biological uptake of DIC by phytoplankton, however, is counteracted by increased oceanic uptake of atmospheric CO2. Despite lower seasonal NPP, years of late sea-ice retreat show larger DIC drawdown, attributed to lower air-sea CO2 fluxes and increased dilution by sea-ice melt. The role of dissolved iron and iron limitation on WAP phytoplankton also remains a challenge due to the lack of data. The model results suggest sediments and glacial meltwater are the main sources in the coastal and shelf regions, with sediments being more influential in the northern coast.
A framework for a marine biodiversity observing network within changing continental shelf seascapes

(The Oceanography Society, 2014-06) Muller-Karger, Frank E. ; Kavanaugh, Maria T. ; Montes, Enrique ; Balch, William M. ; Breitbart, Mya ; Chavez, Francisco P. ; Doney, Scott C. ; Johns, Elizabeth M. ; Letelier, Ricardo M. ; Lomas, Michael W. ; Sosik, Heidi M. ; White, Angelicque E.

Continental shelves and the waters overlying them support numerous industries as diverse as tourism and recreation, energy extraction, fisheries, transportation, and applications of marine bio-molecules (e.g., agribusiness, food processing, pharmaceuticals). Although these shelf ecosystems exhibit impacts of climate change and increased human use of resources (Halpern et al., 2012; IPCC, 2013, 2014; Melillo et al., 2014), there are currently no standardized metrics for assessing changes in ecological function in the coastal ocean. Here, we argue that it is possible to monitor vital signs of ecosystem function by focusing on the lowest levels of the ocean food web. Establishment of biodiversity, biomass, and primary productivity baselines and continuous evaluation of changes in biological resources in these economically and ecologically valuable regions requires an internationally coordinated monitoring effort that fully integrates natural, social, and economic sciences to jointly identify problems and design solutions. Such an ocean observing network is needed to protect the livelihoods of coastal communities in the context of the goals of the Future Earth program (Mooney et al., 2013) and of the Intergovernmental Platform on Biodiversity and Ecosystem Services (http://www.ipbes.net). The tools needed to initiate these assessments are available today.
Effect of continental shelf canyons on phytoplankton biomass and community composition along the western Antarctic Peninsula

(Inter-Research, 2015-03-30) Kavanaugh, Maria T. ; Abdala, F. N. ; Ducklow, Hugh W. ; Glover, David M. ; Fraser, William R. ; Martinson, Douglas G. ; Stammerjohn, Sharon E. ; Schofield, Oscar M. E. ; Doney, Scott C.

The western Antarctic Peninsula is experiencing dramatic climate change as warm, wet conditions expand poleward and interact with local physics and topography, causing differential regional effects on the marine ecosystem. At local scales, deep troughs (or canyons) bisect the continental shelf and act as conduits for warm Upper Circumpolar Deep Water, with reduced seasonal sea ice coverage, and provide a reservoir of macro- and micronutrients. Shoreward of many canyon heads are Adélie penguin breeding colonies; it is hypothesized that these locations reflect improved or more predictable access to higher biological productivity overlying the canyons. To synoptically assess the potential impacts of regional bathymetry on the marine ecosystem, 4 major canyons were identified along a latitudinal gradient west of the Antarctic Peninsula using a high-resolution bathymetric database. Biological-physical dynamics above and adjacent to canyons were compared using in situ pigments and satellite-derived sea surface temperature, sea ice and ocean color variables, including chlorophyll a (chl a) and fucoxanthin derived semi-empirically from remote sensing reflectance. Canyons exhibited higher sea surface temperature and reduced sea ice coverage relative to adjacent shelf areas. In situ and satellite-derived pigment patterns indicated increased total phytoplankton and diatom biomass over the canyons (by up to 22 and 35%, respectively), as well as increases in diatom relative abundance (fucoxanthin:chl a). While regional heterogeneity is apparent, canyons appear to support a phytoplankton community that is conducive to both grazing by krill and enhanced vertical export, although it cannot compensate for decreased biomass and diatom relative abundance during low sea ice conditions.
A three-dimensional mapping of the ocean based on environmental data

(The Oceanography Society, 2017-03) Sayre, Roger ; Wright, Dawn J. ; Breyer, Sean P. ; Butler, Kevin A. ; Van Graafeiland, Keith ; Costello, Mark J. ; Harris, Peter T. ; Goodin, Kathleen L. ; Guinotte, John M. ; Basher, Zeenatul ; Kavanaugh, Maria T. ; Halpin, Patrick N. ; Monaco, Mark E. ; Cressie, Noel ; Aniello, Peter ; Frye, Charles E. ; Stephens, Drew

The existence, sources, distribution, circulation, and physicochemical nature of macroscale oceanic water bodies have long been a focus of oceanographic inquiry. Building on that work, this paper describes an objectively derived and globally comprehensive set of 37 distinct volumetric region units, called ecological marine units (EMUs). They are constructed on a regularly spaced ocean point-mesh grid, from sea surface to seafloor, and attributed with data from the 2013 World Ocean Atlas version 2. The point attribute data are the means of the decadal averages from a 57-year climatology of six physical and chemical environment parameters (temperature, salinity, dissolved oxygen, nitrate, phosphate, and silicate). The database includes over 52 million points that depict the global ocean in x, y, and z dimensions. The point data were statistically clustered to define the 37 EMUs, which represent physically and chemically distinct water volumes based on spatial variation in the six marine environmental characteristics used. The aspatial clustering to produce the 37 EMUs did not include point location or depth as a determinant, yet strong geographic and vertical separation was observed. Twenty-two of the 37 EMUs are globally or regionally extensive, and account for 99% of the ocean volume, while the remaining 15 are smaller and shallower, and occur around coastal features. We assessed the vertical distribution of EMUs in the water column and placed them into classical depth zones representing epipelagic (0 m to 200 m), mesopelagic (200 m to 1,000 m), bathypelagic (1,000 m to 4,000 m) and abyssopelagic (>4,000 m) layers. The mapping and characterization of the EMUs represent a new spatial framework for organizing and understanding the physical, chemical, and ultimately biological properties and processes of oceanic water bodies. The EMUs are an initial objective partitioning of the ocean using long-term historical average data, and could be extended in the future by adding new classification variables and by introducing functionality to develop time-specific EMU distribution maps. The EMUs are an open-access resource, and as both a standardized geographic framework and a baseline physicochemical characterization of the oceanic environment, they are intended to be useful for disturbance assessments, ecosystem accounting exercises, conservation priority setting, and marine protected area network design, along with other research and management applications.
Thirty-three years of ocean benthic warming along the U.S. Northeast Continental Shelf and Slope : patterns, drivers, and ecological consequences

(John Wiley & Sons, 2017-12-04) Kavanaugh, Maria T. ; Rheuban, Jennie E. ; Luis, Kelly M. A. ; Doney, Scott C.

The U.S. Northeast Continental Shelf is experiencing rapid warming, with potentially profound consequences to marine ecosystems. While satellites document multiple scales of spatial and temporal variability on the surface, our understanding of the status, trends, and drivers of the benthic environmental change remains limited. We interpolated sparse benthic temperature data along the New England Shelf and upper Slope using a seasonally dynamic, regionally specific multiple linear regression model that merged in situ and remote sensing data. The statistical model predicted nearly 90% of the variability of the data, resulting in a synoptic time series spanning over three decades from 1982 to 2014. Benthic temperatures increased throughout the domain, including in the Gulf of Maine. Rates of benthic warming ranged from 0.1 to 0.4°C per decade, with fastest rates occurring in shallow, nearshore regions and on Georges Bank, the latter exceeding rates observed in the surface. Rates of benthic warming were up to 1.6 times faster in winter than the rest of the year in many regions, with important implications for disease occurrence and energetics of overwintering species. Drivers of warming varied over the domain. In southern New England and the mid-Atlantic shallow Shelf regions, benthic warming was tightly coupled to changes in SST, whereas both regional and basin-scale changes in ocean circulation affect temperatures in the Gulf of Maine, the Continental Shelf, and Georges Banks. These results highlight data gaps, the current feasibility of prediction from remotely sensed variables, and the need for improved understanding on how climate may affect seasonally specific ecological processes.
Implications of future northwest Atlantic bottom temperatures on the American lobster (Homarus americanus) fishery

(John Wiley & Sons, 2017-12-04) Rheuban, Jennie E. ; Kavanaugh, Maria T. ; Doney, Scott C.

Sea surface temperatures of the northwest Atlantic have warmed dramatically over the last several decades, while benthic temperatures have increased at a slower pace. Here we analyze a subset of the CMIP5 global Earth system model ensemble using a statistical downscaling approach to determine potential future changes in benthic temperatures on the northwest Atlantic continental shelf and slope (<500 m). We put future changes in the context of possible impacts of ocean warming on the high-value, wild-caught American Lobster (Homarus americanus) fishery. Future bottom temperatures of the northwest Atlantic under a business-as-usual (RCP8.5) and a climate-policy (RCP4.5) scenario are projected to increase by 0–1.5°C and 1.2–2.4°C by 2050 and 0–1.9°C and 2.3–4.3°C by the end of the century for RCP4.5 and RCP8.5, respectively. H. americanus experiences thermal stress at temperatures above 20°C, and projected increases in temperature is likely to result in changes in the distribution of optimal thermal egg hatching and settlement indicators. Inshore regions of southern New England, where H. americanus biomass and catch have been declining historically, will likely become inhospitable under either future scenario, while thermal egg hatching and settlement indicators will expand offshore and in the Gulf of Maine. These changes imply that members of the fishery based in southern New England may need to recapitalize to larger vessels to prepare for potential changes brought on by future climate warming. Results from the downscaling presented here can be useful in preparing for potential changes to other fisheries or in future climate vulnerability analyses.
Satellite sensor requirements for monitoring essential biodiversity variables of coastal ecosystems

(John Wiley & Sons, 2018-03-06) Muller-Karger, Frank E. ; Hestir, Erin ; Ade, Christiana ; Turpie, Kevin ; Roberts, Dar A. ; Siegel, David A. ; Miller, Robert J. ; Humm, David ; Izenberg, Noam ; Keller, Mary ; Morgan, Frank ; Frouin, Robert ; Dekker, Arnold G. ; Gardner, Royal ; Goodman, James ; Schaeffer, Blake ; Franz, Bryan A. ; Pahlevan, Nima ; Mannino, Antonio ; Concha, Javier A. ; Ackleson, Steven G. ; Cavanaugh, Kyle C. ; Romanou, Anastasia ; Tzortziou, Maria ; Boss, Emmanuel S. ; Pavlick, Ryan ; Freeman, Anthony ; Rousseaux, Cecile S. ; Dunne, John P. ; Long, Matthew C. ; Salas, Eduardo Klein ; McKinley, Galen A. ; Goes, Joachim I. ; Letelier, Ricardo M. ; Kavanaugh, Maria T. ; Roffer, Mitchell ; Bracher, Astrid ; Arrigo, Kevin R. ; Dierssen, Heidi M. ; Zhang, Xiaodong ; Davis, Frank W. ; Best, Benjamin D. ; Guralnick, Robert P. ; Moisan, John R. ; Sosik, Heidi M. ; Kudela, Raphael M. ; Mouw, Colleen B. ; Barnard, Andrew H. ; Palacios, Sherry ; Roesler, Collin S. ; Drakou, Evangelia G. ; Appeltans, Ward ; Jetz, Walter

The biodiversity and high productivity of coastal terrestrial and aquatic habitats are the foundation for important benefits to human societies around the world. These globally distributed habitats need frequent and broad systematic assessments, but field surveys only cover a small fraction of these areas. Satellite‐based sensors can repeatedly record the visible and near‐infrared reflectance spectra that contain the absorption, scattering, and fluorescence signatures of functional phytoplankton groups, colored dissolved matter, and particulate matter near the surface ocean, and of biologically structured habitats (floating and emergent vegetation, benthic habitats like coral, seagrass, and algae). These measures can be incorporated into Essential Biodiversity Variables (EBVs), including the distribution, abundance, and traits of groups of species populations, and used to evaluate habitat fragmentation. However, current and planned satellites are not designed to observe the EBVs that change rapidly with extreme tides, salinity, temperatures, storms, pollution, or physical habitat destruction over scales relevant to human activity. Making these observations requires a new generation of satellite sensors able to sample with these combined characteristics: (1) spatial resolution on the order of 30 to 100‐m pixels or smaller; (2) spectral resolution on the order of 5 nm in the visible and 10 nm in the short‐wave infrared spectrum (or at least two or more bands at 1,030, 1,240, 1,630, 2,125, and/or 2,260 nm) for atmospheric correction and aquatic and vegetation assessments; (3) radiometric quality with signal to noise ratios (SNR) above 800 (relative to signal levels typical of the open ocean), 14‐bit digitization, absolute radiometric calibration <2%, relative calibration of 0.2%, polarization sensitivity <1%, high radiometric stability and linearity, and operations designed to minimize sunglint; and (4) temporal resolution of hours to days. We refer to these combined specifications as H4 imaging. Enabling H4 imaging is vital for the conservation and management of global biodiversity and ecosystem services, including food provisioning and water security. An agile satellite in a 3‐d repeat low‐Earth orbit could sample 30‐km swath images of several hundred coastal habitats daily. Nine H4 satellites would provide weekly coverage of global coastal zones. Such satellite constellations are now feasible and are used in various applications.
Variability in the mechanisms controlling Southern Ocean phytoplankton bloom phenology in an ocean model and satellite observations

(John Wiley & Sons, 2017-05-30) Rohr, Tyler ; Long, Matthew C. ; Kavanaugh, Maria T. ; Lindsay, Keith ; Doney, Scott C.

A coupled global numerical simulation (conducted with the Community Earth System Model) is used in conjunction with satellite remote sensing observations to examine the role of top-down (grazing pressure) and bottom-up (light, nutrients) controls on marine phytoplankton bloom dynamics in the Southern Ocean. Phytoplankton seasonal phenology is evaluated in the context of the recently proposed “disturbance-recovery” hypothesis relative to more traditional, exclusively “bottom-up” frameworks. All blooms occur when phytoplankton division rates exceed loss rates to permit sustained net population growth; however, the nature of this decoupling period varies regionally in Community Earth System Model. Regional case studies illustrate how unique pathways allow blooms to emerge despite very poor division rates or very strong grazing rates. In the Subantarctic, southeast Pacific small spring blooms initiate early cooccurring with deep mixing and low division rates, consistent with the disturbance-recovery hypothesis. Similar systematics are present in the Subantarctic, southwest Atlantic during the spring but are eclipsed by a subsequent, larger summer bloom that is coincident with shallow mixing and the annual maximum in division rates, consistent with a bottom-up, light limited framework. In the model simulation, increased iron stress prevents a similar summer bloom in the southeast Pacific. In the simulated Antarctic zone (70°S–65°S) seasonal sea ice acts as a dominant phytoplankton-zooplankton decoupling agent, triggering a delayed but substantial bloom as ice recedes. Satellite ocean color remote sensing and ocean physical reanalysis products do not precisely match model-predicted phenology, but observed patterns do indicate regional variability in mechanism across the Atlantic and Pacific.
Changing phytoplankton phenology in the marginal ice zone west of the Antarctic Peninsula

(Inter-Research Science Publisher, 2024-04-18) Turner, Jessica S. ; Dierssen, Heidi M. ; Schofield, Oscar ; Kim, Heather H. ; Stammerjohn, Sharon E. ; Munro, David R. ; Kavanaugh, Maria T.

Climate change is altering global ocean phenology, the timing of annually occurring biological events. We examined the changing phenology of the phytoplankton accumulation season west of the Antarctic Peninsula to show that blooms are shifting later in the season over time in ice-associated waters. The timing of the start date and peak date of the phytoplankton accumulation season occurred later over time from 1997 to 2022 in the marginal ice zone and over the continental shelf. A divergence was seen between offshore waters and ice-associated waters, with offshore bloom timing becoming earlier, yet marginal ice zone and continental shelf bloom timing shifting later. Higher chlorophyll a (chl a) concentration in the fall season was seen in recent years, especially over the northern continental shelf. Minimal long-term trends in annual chl a occurred, likely due to the combination of later start dates in spring and higher chl a in fall. Increasing spring wind speed is the most likely mechanism for later spring start dates, leading to deeper wind mixing in a region experiencing sea ice loss. Later phytoplankton bloom timing over the marginal ice zone and continental shelf will have consequences for surface ocean carbon uptake, food web dynamics, and trophic cascades.

Kavanaugh Maria T.

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