Ocean velocity defines ocean circulation, yet the available observations of subsurface velocity are under-utilized by society. The first step to address these concerns is to improve visibility of and access to existing measurements, which include acoustic sampling from ships, subsurface float drifts, and measurements from autonomous vehicles. While multiple programs provide data publicly, the present difficulty in finding, understanding, and using these data hinder broader use by managers, the public, and other scientists. Creating links from centralized national archives to project specific websites is an easy but important way to improve data discoverability and access. A further step is to archive data in centralized databases, which increases usage by providing a common framework for disparate measurements. This requires consistent data standards and processing protocols for all types of velocity measurements. Central dissemination will also simplify the creation of derived products tailored to end user goals. Eventually, this common framework will aid managers and scientists in identifying regions that need more sampling and in identifying methods to fulfill those demands. Existing technologies are capable of improving spatial and temporal sampling, such as using ships of opportunity or from autonomous platforms like gliders, profiling floats, or Lagrangian floats. Future technological advances are needed to fill sampling gaps and increase data coverage.
Expendable bathythermograph (XBT) data provide one of the longest available records of upper-ocean temperature. However, temperature and depth biases in XBT data adversely affect estimates of long-term trends of ocean heat content and, to a lesser extent, estimates of volume and heat transport in the ocean. Several corrections have been proposed to overcome historical biases in XBT data, which rely on constantly monitoring these biases. This paper provides an analysis of data collected during three recent hydrographic cruises that utilized different types of probes, and examines methods to reduce temperature and depth biases by improving the thermistor calibration and reducing the mass variability of the XBT probes.The results obtained show that the use of individual thermistor calibration in XBT probes is the most effective calibration to decrease the thermal bias, improving the mean thermal bias to less than 0.02 degrees C and its tolerance from 0.1 degrees to 0.03 degrees C. The temperature variance of probes with screened thermistors is significantly reduced by approximately 60% in comparison to standard probes. On the other hand, probes with a tighter weight tolerance did not show statistically significant reductions in the spread of depth biases, possibly because of the small sample size or the sensitivity of the depth accuracy to other causes affecting the analysis.
The circulation and exchange processes controlling transport and water renewal within the western subregion of Florida Bay, USA, are presented and compared to our previous findings for the north-central and northeast subregions of the bay. We find there is a common bank/basin flow response to wind forcing that is the primary driver of water renewal for each of the regions studied. Florida Bay is a patchwork of shallow basins surrounded by very shallow banks that are cut through with deeper channels connecting to nearby basins. We observed that, for each subregion studied, there was a net downwind basin outflow through the larger channels that was approximately balanced by a net basin inflow over the surrounding shallow banks. The resulting basin throughflows are used to estimate exchange times for renewal of western basin waters of approximately 1 mo. This exchange time is sufficient to prevent hypersalinity and degradation of water quality in the western basin, in contrast to the north-central subregion, where hypersalinity development is an annual occurrence. Our results highlight the importance of wind induced water renewal in shallow coastal bays with weak to moderate tidal exchange. In addition, we have discovered a significant clockwise circulation pattern through the western basins from strong inflows of coastal waters through Flamingo Channel that turn southward through the western basins before rejoining the coastal flow toward the Florida Keys tidal passages and Atlantic coastal zone. A practical solution to control hypersalinity, sea grass die-off, and water quality degradation of Florida Bay is proposed.
A new system requiring greatly reduced operator intervention has been developed for the determination of dissolved inorganic carbon concentration in marine waters. Based on a coulometric method, the system has an accuracy and precision comparable to more complex and expensive methods currently employed. A syringe pump equipped with a 12-port distribution valve is used to precisely dispense an acid solution and sample into a gas stripper. The system can autonomously measure eight discrete samples in duplicate or triplicate with no operator input. The best precision (%RSD) obtained was 0.022% (n = 14) or less than ±1.0 μmol kg(-1). The system is calibrated against a certified reference material (CRM). Average offset from the CRM was 1.2 μmol kg(-1). Sample throughput was 4 samples per h. Carryover effects are negligible but field sample analyses suggest that prefiltering may be necessary in highly turbid waters.
Coastal resource management revolves around defining the dynamic between people and the marine and coastal resources they use and depend upon for a large range of goods and services. The process of defining that dynamic is iterative and must account not only for changing natural resource conditions but also for changing social conditions. Decision-making therefore happens within a context of a social system that includes differing levels of capacity, commitment, economics, political mandates and pressures, and cultural and traditional frameworks. The aim of this paper is to introduce a hierarchical approach in which the large number of variables needed to measure the complex, numerous and abstract social concepts used to evaluate the delivery of ecosystem services can be aggregated into smaller sets of indicators, which can ultimately be aggregated into a single report card. These variables and indicators can identify and describe non-economic human dimensions societal benefits derived as ecosystem services that are readily collected, that can identify changes over time, and are appropriate to specific coastal regions. The identified indicators would capture changes in the delivery of overall ecosystem services impacted by, or that will impact, changes in particular sets of environmental characteristics that are valued by society at large.
Enabling ecosystem-based management requires, among other things, reaching a scientifically based consensus with respect to the key characteristics of a sustainable ecosystem capable of supporting those levels of key ecosystem services desired by society. To determine and convey whether an ecosystem is in fact approaching this goal implies developing indicators that capture the status of both the natural and societal aspects of the system. That said, developing consistent and useful indicators for both societal and natural system aspects of the ecosystem requires both resolving disparate perspectives and inconsistent terminology between human dimensions and natural system scientists and keeping the number of indicators manageably few, without oversimplifying a highly complex ecosystem. To accomplish this we employed a "recursive relationship" approach that defined (and redefined) variables, indicators, and indices along a sliding hierarchy from measurable parameters to highly aggregated indices. To illustrate this approach it is applied herein to both a human dimensions index (recreational quality), and a natural sciences index (water column). This "recursive relationship" approach facilitated development of a parsimonious set of high-level indices that together constitute an ecosystem report card integrating natural system status and related societal dimensions from an ecosystem services perspective, while maintaining all of the information at lower levels necessary to inform specific management decisions. Published by Elsevier Ltd.
Your analysis of the long-term investment strategy of the US National Science Foundation (NSF) fails to recognize the extent to which the agency's academic-research fleet is one of the most vital elements of its oceanographic infrastructure (Nature 501, 461; 2013). The increasing complexity of large-scale global programmes on climate and ocean science, such as CLIVAR, GEOTRACES and GeoPRISMS, calls for modern vessels that can host large research groups and that use sophisticated on-board sampling and processing equipment. These vessels are needed for operating state-of-the-art observation systems, interpreting satellite data, and launching and recovering the gliders and autonomous underwater and aerial vehicles used by the ocean research community. The replacement strategy that you criticize is in fact insufficient to replace a research fleet, the age and escalating costs of which mean that it is barely capable of meeting projected scientific requirements — even if all three planned regional research vessels are constructed over the coming decade. It is difficult to provide infrastructure, which takes many years to design and build, with budgets that are unpredictable and constantly changing. Core science budgets should be kept separate from funding for the operation and maintenance of crucial research infrastructure, and not just from its construction. These are complementary rather than competing projects, and both need greater investment. Properly informed, scientifically based policies and strategies will save the public much more money than would be saved by cutting costs on essential scientific infrastructure.
: Our goal is to develop a portable autonomous ammonium sensor. Such a sensor could be deployed for periods of up to a month aboard ships, moorings or drifting buoys or used as a component in lowered or towed oceanographic instrument packages for vertical profiling. Our technical objective is to develop a robust, relatively simple, inexpensive, low power and compact instrument with a detection limit in the nM range and a sampling frequency of at least 6 samples per hour. Robustness, simplicity, low construction cost, lower power and small size are the practical desiderata for commercial application. Commercialization and the lowered instrument costs that will result are essential to permit wider application throughout the oceanographic community.
There is a pressing need to integrate biophysical and human dimensions science to better inform holistic ecosystem management supporting the transition from single species or single-sector management to multi-sector ecosystem-based management. Ecosystem-based management should focus upon ecosystem services, since they reflect societal goals, values, desires, and benefits. The inclusion of ecosystem services into holistic management strategies improves management by better capturing the diversity of positive and negative human-natural interactions and making explicit the benefits to society. To facilitate this inclusion, we propose a conceptual model that merges the broadly applied Driver, Pressure, State, Impact, and Response (DPSIR) conceptual model with ecosystem services yielding a Driver, Pressure, State, Ecosystem service, and Response (EBM-DPSER) conceptual model. The impact module in traditional DPSIR models focuses attention upon negative anthropomorphic impacts on the ecosystem; by replacing impacts with ecosystem services the EBM-DPSER model incorporates not only negative, but also positive changes in the ecosystem. Responses occur as a result of changes in ecosystem services and include inter alia management actions directed at proactively altering human population or individual behavior and infrastructure to meet societal goals. The EBM-DPSER conceptual model was applied to the Florida Keys and Dry Tortugas marine ecosystem as a case study to illustrate how it can inform management decisions. This case study captures our system-level understanding and results in a more holistic representation of ecosystem and human society interactions, thus improving our ability to identify trade-offs. The EBM-DPSER model should be a useful operational tool for implementing EBM, in that it fully integrates our knowledge of all ecosystem components while focusing management attention upon those aspects of the ecosystem most important to human society and does so within a framework already familiar to resource managers.
A portable ammonium analyser was developed and used to measure in situ ammonium in the marine environment. The analyser incorporates an improved LED photodiode-based fluorescence detector (LPFD). This system is more sensitive and considerably smaller than previous systems and incorporates a pre-filtering subsystem enabling measurements in turbid, sediment-laden waters. Over the typical range for ammonium in marine waters (0–10 mM), the response is linear (r(2) = 0.9930) with a limit of detection (S/N ratio > 3) of 10 nM. The working range for marine waters is 0.05–10 mM. Repeatability is 0.3% (n =10) at an ammonium level of 2 mM. Results from automated operation in 15 min cycles over 16 days had good overall precision (RSD = 3%, n = 660). The system was field tested at three shallow South Florida sites. Diurnal cycles and possibly a tidal influence were expressed in the concentration variability observed.
A 38 kHz vessel-mounted acoustic Doppler current profiler is used to explore in detail the dynamics of an anticyclonic and a cyclonic eddy during two transits of the cruise vessel Explorer of the Seas from the Caribbean to New Jersey in July 2007. The radial scale of the two eddies is similar, but whereas the cyclone is strongly surface intensified, the anticyclone has its maximum expression with near-solid body rotation between 200 and 800 m depth. The anticyclone has a minimum in relative vorticity very close to -f at 800 m depth and the cyclone has a maximum of about +1.6 f close to the surface where f is the local Coriolis parameter. By integrating the momentum equation the geopotential anomaly field and hence the potential energy of the eddies can be determined quite accurately, which means that the kinetic and potential energy of the eddies can be determined purely through acoustic remote sensing. Given a density profile just outside the eddy one can integrate the gradient wind equation to obtain an estimate of the density and hence potential vorticity fields through the two eddies. The acoustic backscatter patterns in the eddies are quite distinct from the surrounding waters. The backscatter intensity of the main scattering layer at similar to 600 m depth decreases by similar to 10 dB in the core of both eddies. In the cyclonic eddy three identifiable scattering layers in the main thermocline show a strong tendency for the scattering layer to track the shoaling density structure toward the center of the eddy.
An autonomous batch analyzer (ABA) is described for the measurement of ammonium in natural waters. The system combines previously described batch analysis and continuous flow analysis methods. With its simpler design, the system is robust, flexible, inexpensive, and requires minimal maintenance. The sampling frequency is ca. 8 h−1 and the limit of detection ca. 1 nM which is comparable to the most sensitive flow through or batch analysis methods previously described. Reproducibility is 0.6% (n = 10) at an ammonium level of 200 nM. There are three working ranges: 5–1000 nM, 20–4000 nM, and 0.2–25 μM. In addition, the system produces a calibration curve by autodilution from a single stock standard solution with the same accuracy as traditional manual calibration methods. Representative field data and comparisons with standard EPA methods confirm the utility of the ABA.
Quantifying the relationship between mesozooplankton and water quality parameters identifies the factors that structure the mesozooplankton community and can be used to generate hypotheses regarding the mechanisms that control the mesozooplankton population and potentially the trophic network. To investigate this relationship, mesozooplankton and water quality data were collected in Florida Bay from 1994 to 2004. Three key characteristics were found in the mesozooplankton community structure: (1) there are significant differences between the four sub-regions of Florida Bay; (2) there is a break in May of 1997 with significant differences before and after this date; and (3) there is a positive correlation between mesozooplankton abundance and salinity. The latter two characteristics are closely correlated with predator abundance, indicating the importance of top-down control. Hypersaline periods appear to provide a refuge from predators, allowing mesozooplankton to increase in abundance despite the increased physiological stress.