Building a window to the sea : Ocean Research Interactive Observatory Networks (ORION)

Author Posting. © Oceanography Society, 2004. This article is posted here by permission of Oceanography Society for personal use, not for redistribution. The definitive version was published in Oceanography 17, 2 (2004): 113-120.For centuries, oceanographers have relied on data and observations about the ocean and the seafloor below gathered from ships during cruises of limited duration. This expeditionary research approach has resulted in major advances in understanding global ocean circulation, the energy associated with mesoscale circulation, plate tectonics, global ocean productivity, and climate-ocean coupling. These and many other successes have expanded our view of Earth and ocean processes, and have demonstrated a need for sampling strategies spanning temporal and spatial scales not effectively carried out using ships. To address this observational gap, community efforts in the United States consistently have recommended that funding agencies support development of the capability to maintain a continuous sampling and monitoring presence in the ocean.MKT is grateful for support from a WHOI Deep Ocean Exploration Institute fellowship

a aparición de regularidades y variabilidad en ecosistemas marinos: el papel combinado de la física, la química y la biología

Marine ecosystems play an integral role in the functioning of life on earth. To predict how they will respond to global changes, and to effectively manage and maintain services upon which humans rely, we must understand how biological processes at the cellular level generate macroscopic patterns in the oceans. Here, we discuss how physics and biogeochemistry influence and constrain marine ecosystem structure and function, and outline key regularities and patterns of variability that models should aim to reproduce. We identify unanswered questions regarding how size-dependent physiological and ecological processes are linked to turbulent mixing, dealing specifically with how size structure is related to mixing over a range of spatial scales and how it is linked to the fate of primary production in the sea.Los ecosistemas marinos juegan un papel integral en el funcionamiento de la vida sobre la Tierra. Para predecir cómo van a responder a cambios globales y para mantener los servicios de los cuales los humanos dependemos, tenemos que comprender cómo los procesos biológicos a nivel celular generan patrones macroscópicos en el océano. Examinamos cómo la física y la biogeoquímica afectan y limitan la estructura y función de los ecosistemas marinos, y exponemos importantes regularidades y patrones de variabilidad que los modelos deberían reproducir. Identificamos aspectos sin resolver sobre la relación entre procesos fisiológicos y ecológicos y la mezcla turbulenta. En concreto, cómo la estructura de tamaños está relacionada con la mezcla en un rango de escalas espaciales y cómo está conectada con el destino de la producción primaria en el mar

Impacts of a Recurrent Resuspension Event and Variable Phytoplankton Community Composition On Remote Sensing Reflectance

In order to characterize the impact of turbidity plumes on optical and biological dynamics, a suite of environmental parameters were measured in southern Lake Michigan during the springtime recurrent sediment plume. In-water measurements of inherent optical properties (IOPs) were entered into the Hydrolight 4.2 radiative transfer model and the output was compared with measured apparent optical properties (AOPs) across a wide range of optical conditions. Hydrolight output and measured underwater light fields were then used to clarify the effects of the sediment plume on primary production, phytoplankton community composition, and nearshore remote sensing ocean color algorithms. Our results show that the sediment plume had a negligible effect on the spectral light environment and phytoplankton physiology. The plume did not significantly alter the spectral quality of available light and did not lead to light limited phytoplankton populations compared to non-plume conditions. Further, the suspended sediment in the plume did not seriously impact the performance of ocean color algorithms. We evaluated several currently employed chlorophyll algorithms and demonstrated that the main factor compromising the efficacy of these algorithms was the composition of phytoplankton populations. As phycobilin-containing algae became the dominant species, chlorophyll algorithms that use traditional blue/green reflectance ratios were compromised due to the high absorption of green light by phycobilin pigments. This is a notable difficulty in coastal areas, which have highly variable phytoplankton composition and are often dominated by sharp fronts of phycobilin and non-phycobilin containing algae

Zooplankton diel vertical migration during Antarctic summer

Zooplankton diel vertical migration (DVM) during summer in the polar oceans is presumed to be dampened due to near continuous daylight. We analyzed zooplankton diel vertical distribution patterns in a wide range of taxa along the Western Antarctic Peninsula (WAP) to assess if DVM occurs, and if so, what environmental controls modulate DVM in the austral summer. Zooplankton were collected during January and February in paired day-night, depth-stratified tows through the mesopelagic zone along the WAP from 2009-2017, as well as in day and night epipelagic net tows from 1993-2017. The copepod Metridia gerlachei, salp Salpa thompsoni, pteropod Limacina helicina antarctica, and ostracods consistently conducted DVM between the mesopelagic and epipelagic zones. Migration distance for M. gerlachei and ostracods decreased as photoperiod increased from 17 to 22 h daylight. The copepods Calanoides acutus and Rhincalanus gigas, as well as euphausiids Thysanoessa macrura and Euphausia crystallorophias, conducted shallow (mostly within the epipelagic zone) DVMs into the upper 50 m at night. Rhincalanus gigas, T. macrura, and L. h. antarctica DVM behavior was modulated by chlorophyll a concentration, mixed layer depth, and depth of the subsurface chlorophyll a maximum, respectively. Carnivorous and detritivorous taxa – including the calanoid copepod Paraeuchaeta antarctica, ostracods, chaetognaths, and Tomopteris spp. polychaetes – as well as seasonally migrating copepods, were most abundant in the mesopelagic zone regardless of the diel cycle. Paraeuchaeta antarctica underwent reverse DVM within the top 100 m. The impacts of Antarctic zooplankton summer DVM and the resident mesopelagic assemblage on carbon export should be better quantified

Zooplankton Avoidance of a Profiled Open-Path Fluorometer

Significant avoidance of acoustically detected zooplankton was observed in response to a profiling instrument package. Avoidance decreased acoustic scattering from zooplankton averaged over the entire profile by more than a factor of 2, while the maximum avoidance decreased zooplankton acoustic scattering by a factor of 15 over the depth of some discrete scattering layers. Experimental manipulation of the profiler and its instruments revealed that an open-path fluorometer was triggering the avoidance. Avoidance occurred at an average of 8 m below the profiler with a range between 2 and 13 m. Effect range was positively correlated with the average attenuation coefficient of light over the effect range and consistently resulted in avoidance when light levels of approximately 0.013 µmol photons m−2 s−1 were received by the zooplankton. These results have important implications for the analysis of zooplankton data collected from platforms carrying open-path fluorometers and may also warrant careful interpretation of optical measurements from these packages

Variability and change in the west Antarctic Peninsula marine system: Research priorities and opportunities

The west Antarctic Peninsula (WAP) region has undergone significant changes in temperature and seasonal ice dynamics since the mid-twentieth century, with strong impacts on the regional ecosystem, ocean chemistry and hydrographic properties. Changes to these long-term trends of warming and sea ice decline have been observed in the 21st century, but their consequences for ocean physics, chemistry and the ecology of the high-productivity shelf ecosystem are yet to be fully established. The WAP shelf is important for regional krill stocks and higher trophic levels, whilst the degree of variability and change in the physical environment and documented biological and biogeochemical responses make this a model system for how climate and sea ice changes might restructure high-latitude ecosystems. Although this region is arguably the best-measured and best-understood shelf region around Antarctica, significant gaps remain in spatial and temporal data capable of resolving the atmosphere-ice-ocean-ecosystem feedbacks that control the dynamics and evolution of this complex polar system. Here we summarise the current state of knowledge regarding the key mechanisms and interactions regulating the physical, biogeochemical and biological processes at work, the ways in which the shelf environment is changing, and the ecosystem response to the changes underway. We outline the overarching cross-disciplinary priorities for future research, as well as the most important discipline-specific objectives. Underpinning these priorities and objectives is the need to better define the causes, magnitude and timescales of variability and change at all levels of the system. A combination of traditional and innovative approaches will be critical to addressing these priorities and developing a co-ordinated observing system for the WAP shelf, which is required to detect and elucidate change into the future

Krill availability in adjacent Adélie and gentoo penguin foraging regions near Palmer Station, Antarctica

The Palmer Deep canyon along the West Antarctic Peninsula is a biological hotspot with abundant phytoplankton and krill supporting Adélie and gentoo penguin rookeries at the canyon head. Nearshore studies have focused on physical mechanisms driving primary production and penguin foraging, but less is known about finer-scale krill distribution and density. We designed two acoustic survey grids paired with conductivity–temperature–depth profiles within adjacent Adélie and gentoo penguin foraging regions near Palmer Station, Ant-arctica. The grids were sampled from January to March 2019 to assess variability in krill availability and associations with oceanographic properties. Krill density was similar in the two regions, but krill swarms were longer and larger in the gentoo foraging region, which was also less stratified and had lower chlorophyll concentrations. In the inshore zone near penguin colonies, depth-integrated krill density increased from summer to autumn (January–March) independent of chlorophyll concentration, suggesting a life history-driven adult krill migration rather than a resource-driven biomass increase. The daytime depth of krill biomass deepened through the summer and became decoupled from the chlorophyll maximum in March as diel vertical migration magnitude likely increased. Penguins near Palmer Station did not appear to be limited by krill availability during our study, and regional differences in krill depth match the foraging behaviors of the two penguin species. Understanding fine-scale physical forcing and ecological interactions in coastal Antarctic hotspots is critical for predicting how environmental change will impact these ecosystems

The emergence of regularity and variability in marine ecosystems: the combined role of physics, chemistry and biology

Marine ecosystems play an integral role in the functioning of life on earth. To predict how they will respond to global changes, and to effectively manage and maintain services upon which humans rely, we must understand how biological processes at the cellular level generate macroscopic patterns in the oceans. Here, we discuss how physics and biogeochemistry influence and constrain marine ecosystem structure and function, and outline key regularities and patterns of variability that models should aim to reproduce. We identify unanswered questions regarding how size-dependent physiological and ecological processes are linked to turbulent mixing, dealing specifically with how size structure is related to mixing over a range of spatial scales and how it is linked to the fate of primary production in the sea

Detection of Harmful Algal Blooms Using Photopigments and Absorption Signatures: A Case Study of the Florida Red Tide Dinoflagellate, Gymnodinium breve

The utility of photopigments and absorption signatures to detect and enumerate the red tide dinoflagellate, Gymnodinium breve, was evaluated in laboratory cultures and in natural assemblages. The carotenoid, gyroxanthindiester, was an adequate biomarker for G. breve biomass; water‐column concentrations corresponded with cell standing crops and chlorophyll a concentrations during bloom events in Sarasota Bay, Florida. Unlike other carotenoids, the relative abundance of gyroxanthin‐diester did not change throughout a range of physiological states in culture and the gyroxanthin‐diester: chlorophyll a ratio exhibited little variability in a natural assemblage during bloom senescence. Stepwise discriminant analysis indicated that wavelengths indicative of in vivo absorption by accessory chlorophylls and carotenoids could correctly discern spectra of the fucoxanthin‐containing G. breve from spectra of peridinin‐containing dinoflagellates, a diatom, a haptophyte, and a prasinophyte. With the use of a similarity algorithm, the increasing contribution of G. breve was discerned in absorption spectra (and corresponding fourth‐derivative plots) for hypothetical mixed assemblages. However, the absorption properties of chlorophyll c‐containing algae vary little among taxa and it is difficult to discern the contribution of accessory chlorophylls and carotenoids caused by cell packaging. Therefore, the use of absorption spectra alone may not identify the contribution of a chlorophyll c‐containing taxon to the composite spectrum of a mixed assemblage. This difficulty in distinguishing among spectra can be minimized by using the similarity algorithm in conjunction with fourth‐derivative analysis