Lead Investigators

Gaurav S. Sukhatme, Department of Computer Science, USC; David A. Caron, Department of Biological Sciences, USC

Overview

This application area focuses on creating and applying a new genre of sensor networks for making observations in aquatic ecosystems that will enable the generation (and testing) of novel hypotheses regarding the processes that control the distribution, growth and demise of planktonic microbial populations.  Our primary and continuing long-term scientific goal is to understand and ultimately predict the conditions under which specific populations of marine microorganisms develop in nature. A fundamental requirement for attaining this objective is the correlation of environmental conditions and driving forces with microorganismal abundances at the small spatial and temporal scales that are relevant to the microorganisms.

Our work combines laboratory development and field deployment of technology for in-situ, real-time studies of microbial assemblages and concomitant environmental parameters.  Laboratory studies provide a testbed for the development and testing of hardware and software for novel sensing/sampling approaches, and for experimental studies of plankton behavior (growth, vertical migration, trophic interactions).  Our unique approach to aquatic sensing and sampling, Networked Aquatic Microbial Observing Systems (NAMOS), employs coordinated measurements between stationary sensing nodes and robotic vehicles to provide in-situ, real-time presence for observing plankton dynamics (e.g. chlorophyll concentration), and linking them to environmental variables (e.g. temperature, light, nutrients, etc.).  Sampling capabilities of autonomous vehicles are carried out as adaptive sampling protocols, directed through the network, for the collection and analysis of samples.

The development of new sensors, or new detection protocols, has been a minor component of this project.  This work has largely been performed in coordination with other CENS groups whose primary objective is the development of innovative sensors.

Approach

Our goal for the field component of Networked Aquatic Microbial Observing Systems  is to develop robust, decentralized algorithms and supporting hardware that enable a wireless sensor network consisting of sensor-equipped buoys (or pier-based sensor packages) and a sensor/sampler-equipped autonomous vehicle (robotic boat) that can perform adaptive hydrographic and biological sampling using the information provided by the network.  Field studies to date have focused on Lake Fulmor at the James Reserve in the San Jacinto Mountains during 2005 and 2006, and more recently in King Harbor of the City of Redondo Beach along the Southern California Bight.  Lake Fulmor has provided an interesting natural testbed for our work and an excellent opportunity for interacting with other components of the CENS community.  Redondo Beach represents our first full ‘build out’ in a marine ecosystem, and a new and potentially far-reaching beginning of a relationship with the City to address issues of coastal water quality.  While the work performed in King Harbor will address a specific issue of water quality, we feel that this project will generate a ‘template’ that other coastal municipalities will be able to use to design coastal monitoring networks that are applicable to their particular situations.

Our laboratory work continues to involve the development and testing of novel sensors/samplers, the development of supporting software and hardware, and the testing of these novel approaches in ‘artificial water columns’ used to simulate natural plaktonic environments.  For this work we have focused primarily on studies of the ecology of harmful algal blooms (Aureococcus anophagefferens, the cause of brown tides of the Middle Atlantic States); Lingulodinium polyedrum, the cause of intense red tides of the Southern California Bight).  Studies of these organisms not only provide an excellent means of testing new sensing/sampling approaches but also have yielded useful insights into the factors controlling the growth and aggregation of harmful algal bloom-forming species of phytoplankton.  More recently, a research group headed by Jennifer Jay and William Kaiser have developed a near real-time method for detecting Escherichia coli in a natural assemblage of bacteria using immunomagnetic separation.

Systems/Experiments

Much of our field work during the past 2 years has centered on the deployment and refinement of NAMOS (Networked Aquatic Microbial Observing Systems) within Lake Fulmor of the James Reserve. The stationary nodes of the network have consisted of up to 9 moored sensor buoys (Fig. 1) equipped with strings of thermistors which provide information on the vertical temperature structure within the lake, and submersible fluorometers (for measurement of chlorophyll concentrations) at 0.5 m depth in the lake.

Figure 1. Moored sensor-buoy within the NAMOS wireless sensor network. For details see Actuation section.

Thermistor strings provide vertical and horizontal patterns of temperature, and temporal patterns temperature on time scales from seconds to days). Fluorometers provide near-surface spatial (horizontal) patterns of chlorophyll, and temporal patterns scales of seconds to days).

Figure 2. Areal photograph of Lake Fulmor. Arrows show approximate buoy locations of one deployment.

Three studies were conducted in Lake Fulmor during 2005 (May, July, October), and deployments were repeated three times in 2006. In 2006, our deployments were performed in coordination with the UCLA’s Networked Infomechanical Systems (NIMS) group. Therefore, we obtained unprecedented coverage of chemical/physical parameters within the lake. Measurements included 2-3 days of continuous sensor measurements at the buoy locations in the lake, ‘whole lake’ coverage of surface chlorophyll distributions using the robotic boat, and vertical cross-sectional profiles of chemical and physical parameters across the lake using the NIMS. Experiments during all three deployments employed at least five buoys along the length of the lake in order to examine spatial heterogeneity in temperature and chlorophyll throughout the lake (Fig. 2).

Measurements made by static (i.e. moored) sensor buoys in NAMOS were augmented by the activities of an autonomous surface vehicle (a robotic boat) that can take carry out sensing/sampling missions based on a set of preprogrammed commands or can be controlled wirelessly and manually (Fig. 3). The prototype boat is equipped with a fluorometer to enable the acquisition of high-resolution spatial patterns of chlorophyll concentrations.

Figure 3. A prototype version of the robotic boat used at Lake Fulmor. The carousel at the top of the boat is a multiple sampler collector.

A new version of this boat (Q-boat) is presently in service that can lift a sensor package through the water column and thereby provide vertical profiles of depth, salinity, temperature, chlorophyll fluorescence, dissolved oxygen (Fig. 4).

 

The studies in Lake Fulmor have enabled unique and insightful observations of the planktonic assemblages in this environment (see Accomplishments below). Moreover, these initial observations serve as the basis for new hypotheses on ecosystem structure and function in this freshwater environment, which in turn stimulates new sensor network approaches. This iterative process drives the development of embedded networked sensing, and the scientific findings of these experiments drives the application domain (see Future Directions below).

Figure 4. We acquired a new robotic boat in 2006 that is equipped with GPS, compass, and sensor package that can be lowered on a wire to provide a vertical profile of pertinent environmental parameters.

Experiments in the laboratory component of the Aquatic Microbial Observing Systems have been carried out primarily in a 2-meter water column. This ‘artificial water column’ is illuminated from above and cooled at the bottom to produce a realistic, stratified water column. This laboratory testbed is simplistic in its composition but it is an effective means of simulating a natural water column (Fig. 5). The use of such experimental microcosms are a mainstay of aquatic microbial ecology. The development of our testbed enables the design and testing of new approaches for sensing and sampling vertically in the water.

Figure 5. Experimental testbed for examining plankton dynamics, and also for the development and testing of hardware and software for sensing and sampling in aquatic ecosystems.

To date, water column experiments in the laboratory have focused on two species of harmful bloom-forming algae (Aureococcus anophagefferens, the cause of ‘brown tides’ of the Middle Atlantic States, and Lingulodinium polyedrum, a cause of ‘red tides’ along the California coast). These lab setups also provide a mechanism for testing new sensing technologies based in novel genetic, immunological and instrumentational approaches for microorganismal detection and enumeration (see Sensors section). The long-term goal of this work is the integration of these different technologies and approaches (embedded networked sensors, novel microorganismal identification) to provide the next generation of tools for studying these organisms in natural settings.

Accomplishments

Freshwater Field Deployments:

A major effort has been exerted during the past two years within the NAMOS component of CENS to deploy and apply a functioning network working in a natural freshwater ecosystem. Towards this end, a multi-node (5-9), wireless network of sensor-equipped buoys has been deployed repeatedly in Lake Fulmor of the James Reserve during 2005 and 2006. Coordinated measurements between stationary sensing nodes and a robotic boat have been demonstrated to provide high-resolution temporal and spatial information on temperature and phytoplankton (chlorophyll) distribution within the lake. These observations have resulted in novel hypotheses focused on the role of vertical migratory behavior in nutrient acquisition and community dominance by phytoplankton species. Increasingly sophisticated deployments and experiments have driven the development of robust adaptive sensing and sample collection, enabling previously unachievable observations. During 2006, three extensive field campaigns were carried out in Lake Fulmor in conjunction with the NIMS component of CENS (see NIMS section of Annual Report). These joint studies yielded unprecedented horizontal and vertical coverage of phytoplankton distributions and chemical/physical parameters within the lake.

Previous years’ work to build an aquatic sensor network has incrementally provided the hardware and software advances necessary to enable deployment. Among other accomplishments, these advances have included: (1) Design and construction of moored sensor buoys (presently capable of continuous depth-resolved temperature measurements and fluorometric measurements of chlorophyll at 0.5 m). (2) Design and construction of an autonomous sensing/sampling vehicle (robotic boat) with directed navigation that can integrate with the static node network, make continuous underway fluorometric measurements of chlorophyll, and collect surface water samples at designated locations. (3) Development of software for network communication, within-network data synthesis, and transmission of network information to a land-based station for visualization and data storage. (4) Development of efficient, distributed navigation algorithms to enable autonomous operation of the robotic boat (including a bacterium-inspired algorithm for robot navigation and homing with minimal computational requirements), integration into the existing network of static nodes and adaptive sampling by the vehicle. (5) Design and construction of a new robotic boat with enhanced capabilities. Specifically, the new Q-boat design (Ocean Science, Inc.; Oceanside, CA) is equipped with a computer-controlled on-board winch which lowers a sensor package vertically in the water at desired locations to obtain vertical profiles of water column chemistry and physics (presently equipped with sensors for determination of water depth, temperature, conductivity [salinity], fluorescence [chlorophyll] and dissolved oxygen).

A primary goal and accomplishment of the Lake Fulmor studies during 2006 was the use of the sensor network (and NIMS) to obtain ‘systems-level’ measurements of the lake. These measurements worked towards developing a model that will capture the important chemical, physical and biological structure of the lake, and thereby enable characterization of the major biogeochemical processes within the lake. Seasonal studies in Lake Fulmor were aimed at obtaining system-level (i.e. whole lake) reconstructions of the spatial (vertical and horizontal) and temporal (scales of minutes to seasons) characterization of features pertinent to aquatic microbial ecology. Observational measurements made by the static network and robotic boat were complemented with measurements of nutrient chemistry, microbial biomass, water flow (to establish residence times for water in the epilimnion and hypolimnion of the lake), and rates of important biological processes. To our knowledge, these deployments, aided by hypotheses generated as consequence of deployments in 2005, were unique among applications of the sensor networks to address questions of import to limnological research.

Three NAMOS lake deployments were conducted in conjunction with the Networked InfoMechanical Systems (NIMS) group. This work allowed a first-ever integration and comparison between these sensing networks, and is part of a thrust into developing multi-scale sensing as a component of embedded networks. We examined the value-added of sampling at high spatial/temporal resolution (compared to the relatively sparse sampling that characterizes most biological studies in aquatic ecosystems). The vast number of scales over which environmental processes operate make multi-scale sensing an essential component of environmental networks. In addition, network flexibility also constituted an important aspect of our efforts to improve network functionality for environmental sensing. The use of network output from low-density sensors to trigger reconfiguration of the network, or to trigger high-resolution measurements/sampling when it is needed will be an important part of future network designs and applications.

Six field deployments of the NAMOS were conducted in 2005 and three in 2006 in Lake Fulmor of James Reserve. Deployments during May, July and October of 2005 and May, June and August of 2006 represented different goals of development, testing and improvement of the sensor network and the robotic boat (see Actuation and Multiscale Actuated Sensing). However, data collected during each deployment provided an interesting and unique insight into the structure of the planktonic community in the lake. All six deployments involved measurements made from a static, moored sensor array of at least five nodes (the deployment in October 2005 also involved a deployment of 4 additional nodes to begin to examine multiscale sensing). The deployments in 2006 were all conducted in conjunction with the NIMS team.

Placement of the five buoys was similar for all deployments (Fig. 6). This arrangement provided information from various locations along the length of the lake. Retention of these same locations facilitated comparisons among the six deployments.

Figure 6. Location of static sensor nodes (buoys) within Lake Fulmor during network deployments in May, July and October 2005, and May, June and August of 2006.

Chlorophyll fluorescence at 0.5 m depth and temperature (depth-resolved) is provided in Figs. 7-10 from the deployments in 2005. Similar patterns were obtained during 2006. Lake characteristics were very consistent between the 2 years. Information was collected over the course of 2-4 days for each deployment. Figs. 7-9 provide contours of the spatial patterns of the two parameters at the buoys at four specific times of day (6am, noon, 6pm and midnight).

The May 2005 deployment (Figure 7) revealed minor thermal stratification of the water column, with considerable warming of surface waters during the daylight period, with cooling during the night. Nighttime cooling yielded a nearly isothermal water column by morning. Chlorophyll concentrations were modest and did not indicate major spatial heterogeneity or temporal heterogeneity over a 24 hour period. The lower lake area (southwest) had slightly higher chlorophyll concentrations than the upper (inlet) end, but overall chlorophyll remained below approximately 20 µg l^-1.

Figure 7. Chlorophyll at 0.5 m depth (top graph in each panel) and depth-resolved temperature patterns during May 2005 in Lake Fulmor. Measurements were made at approximately 6am (top left), noon (top right), 6pm (bottom left) and midnight (bottom right).

Figure 8. Chlorophyll at 0.5m depth (top graph in each panel) and depth-resolved temperature patterns during July 2005 in Lake Fulmor. Measurements were made at approximately 6am (top left), noon (top right), 6pm (bottom left) and midnight (bottom right).

Figure 9. Chlorophyll at 0.5 m depth (top graph in each panel) and depth-resolved temperature patterns during October 2005 in Lake Fulmor. Measurements were made at approximately 6am (top left), noon (top right), 6pm (bottom left) and midnight (bottom right).

Figure 10. Chlorophyll at 0.5 m depth (top graph in each panel) and depth-resolved temperature patterns during October 2005 in Lake Fulmor. Measurements were made at approximately 6am (top left), noon (top right), 6pm (bottom left) and midnight (bottom right). Data from 4 additional buoys have been added to provide higher resolution in the lower portion of the lake.

Temperature and chlorophyll patterns observed using the sensor network during the July 2005 deployment were in sharp contrast to patterns observed during May 2005 (Figure 8). Water temperature was higher than May (up to 25˚C) and relatively isothermal throughout the lake, with the exception of one area of the lake that indicated significant turnover of the lake (presumably due to late afternoon wind). Chlorophyll concentrations during most of the day were relatively homogeneous throughout the lake, but showed a dramatic increase during the night (note midnight pattern; Fig. 8, bottom right). We interpret this pattern as indicating a major diel vertical migration of phytoplankton (see Figures 11-13, below).

Water temperature throughout the lake during the October 2005 deployment was again isothermal and moderate (approximately 10-13˚C), and a highly heterogeneous pattern of chlorophyll was observed spatially throughout the lake and temporally over a diel cycle. The sensor network during October 2005 was supplemented with additional buoys in the lower (southwest) portion of the lake in order to examine how high-density spatial sampling could improve resolution of the temperature and chlorophyll patterns (Figure 10). This constituted our first attempt to directly examine multi-scale sensing. Increased sensor density revealed heterogeneity in both chlorophyll and temperature that were not detected by the less-dense sensor network (compare panels Figs. 9 and 10).

In 2006, we examined small-scale spatial and vertical heterogeneity in phytoplankton biomass (and a variety of other chemical/physical parameters) through the deployment of the NIMS in conjunction with the NAMOS. The NIMS was deployed east-west across the lower third of Lake Fulmor to provide centimeter-resolved information horizontally and vertically. These ‘cross-sections’ of the lake were performed at several times of day to provide information on both spatial (vertically and horizontally) and temporal (hours) changes in the plankton community. A diel vertical migration of a significant component of the phytoplankton assemblage was demonstrated using the NIMS by the vertical displacement of the chlorophyll maximum in the lake over a 24 hour period. The combined use of NIMS and NAMOS yielded a powerful investigative approach for examining the spatiotemporal distribution of phytoplankton and pertinent environmental forcing factors in the lake.

The static buoy sensor network enabled the investigation of small-scale temporal patterns of temperature and chlorophyll ranging from seconds to days for the six deployments (e.g. Figure 11-13). As observed for the spatial patterns, continuous chlorophyll measurements indicated peaks of chlorophyll in the 20-30 µg l^-1 range. Also evident were distinct peaks occuring near midnight. This pattern is highly unusual, and raises interesting questions about the biology giving rise to this pattern. A similar diel pattern was observed during July 2005 (Figure 12), October 2005 (Figure 13) and all 3 deployments in 2006, although chlorophyll concentrations were dramatically higher at the time later in the year. Differences in the phytoplankton assemblages of the lake were observed between the July and October 2005 deployments (Figures 14, 15). Similar phytoplankton composition was observed during June and August of 2006. A colonial diatom (Asterionella) strongly dominated during May 2006.

Figure 11. Chlorophyll at 0.5 m depth (green) and depth-resolved temperature at four static sensor nodes over approximately three days during May 2005 in Lake Fulmor.

Figure 12. Chlorophyll at 0.5 m depth (green) and depth-resolved temperature at four static sensor nodes over approximately three days during July 2005 in Lake Fulmor.

Figure 13. Chlorophyll at 0.5 m depth (green) and depth-resolved temperature at four static sensor nodes over approximately three days during October 2005 in Lake Fulmor. The pattern of chlorophyll fluorescence observed in mid-late summer was investigated in 2006. Photoadaptation of the phytoplankton assemblage to high light intensity in the lake resulted in the precipitous decreases in chlorophyll fluorescence apparent at mid-day.

Figure 14. Phytoplankton present during the July 2005 plankton of Lake Fulmor. Dominant taxa included several filamentous cyanobacteria Spirulina (left top), Anabaena (top center), Microcystis (left bottom and right) and the dinoflagellate Ceratium, (center bottom). Spirulina is known to undergo vertical migration and aggregation.

 

Figure 15. Phytoplankton present during the October 2005 plankton of Lake Fulmor. Dominant taxa included several filamentous cyanobacteria Anabaena (left top and bottom), Aphanizomenom (center top and bottom), and diatoms (left top and bottom). Aphanizomenom was a major contributor to phytoplankton biomass during the October experiment.

Progress has also continued to be realized with respect to the application of our robotic boats for autonomous missions, redirection during a mission, and obstacle avoidance. The control and navigation of the boat have been advanced considerably.

Marine Coastal Deployments:

We have recently initiated a joint project with the City of Redondo Beach. The goal of our research is the design and implementation of an ‘environmental sensor network’ that will vastly increase our ability to make observations in nature, and thereby identify linkages between environmental forcing factors and ecosystem response. We have chosen King Harbor of the City of Redondo Beach as our test site with the overall goal of understanding the factors leading to recurring algal blooms and recent fish kills in the harbor. King Harbor is an enclosed series of basins housing three marinas, and is contiguous with the Redondo Beach Pier and Esplanade. Unprecedented algal blooms in King Harbor have resulted in massive fish kills in 2005, and recurring blooms during 2006. Our present work is designed to examine water chemistry within the harbor and its relationship to algal blooms and fish kills. The short-term goals of applying sensor network technology to (1) determine the immediate cause of the fish kills, and (2) evaluate approach(es) to mitigate these events. Long term goals would attempt to develop an understanding of the factors leading to fish kills, with the ultimate goal of preventing these harmful events. The ‘CENS related’ goal of this project is the design, construction and implement a sensor network that will have practical and specific application to a societally relevant issue involving water quality in a coastal ecosystem. We envision this project as addressing an existing environmental issue, but also as a means of developing a ‘template’ that can be adapted in the future to provide sensor networks for applications in other coastal environments with other water quality issues.

The static components of the network (i.e. sensor-equipped buoys) constitute a ‘sentinel’ activity to monitor constantly for signs of an emerging environmental issue (in this case, a ‘red tide’ of other harmful algal bloom). When a developing problem is identified, this will trigger a rapid response and deployment of the robotic boat for synoptic measurements of pertinent environmental parameters (including chlorophyll concentration) to characterize the emerging event and its possible driving factors. The combined buoy/boat data would then direct manual and/or automated sample collection and also experimental field work by the research team. This work will enable a ‘system-level’ analysis and modeling effort of the harbor, as is presently underway with our Lake Fulmor dataset. The use our robotic boat within the harbor in conjunction with the sensor buoys has allowed us to begin to fully characterize the harbor water column (Fig. 16).

Figure 16. A NAMOS buoy deployed in King Harbor of the City of Redondo Beach during 2007 (left). On the right are time-series measurements of temperature at six depths over a 3-day period (right, top) and chlorophyll fluorescence at 0.5 m depth over a 2-day period (right, bottom). A substantial tidal influence on chlorophyll fluorescence was present in the temporal pattern.

Fine-scale temporal patterns (Fig. 16) and coarse-scale horizontal spatial patterns of phytoplankton biomass (i.e. chlorophyll fluorescence) derived from the network of sensor buoys will be combined with information obtained using the robotic boat which provides fine-scale spatial resolution vertically in the water column (Fig. 17) as well as the ability to obtain increase the resolution of horizontal spatial distributions of sensed parameters. Characterization of both the vertical and horizontal distribution of biomass and environmental parameters in King Harbor will be essential for resolving the cause of fish kills there because the present assumptions are that (1) the immediate cause of the fish kills is the depletion of dissolved oxygen in the water during blooms (temporal and horizontal variability in dissolved oxygen concentration will be measured in by the buoys and boat, respectively), and (2) these blooms are not produced within the harbor but rather develop in coastal waters and are advected into the harbor. The latter issue will be addressed by examining the appearance of the bloom across the coarse spatial (horizontal) grid provided by the network of buoys, with increased resolution provided by the robotic boat.

Figure 17. A vertical profile of sensed parameters (temperature, salinity, dissolved oxygen, chlorophyll fluorscenence) obtained using the robotic Q-boat.

Sensor Development for Coastal Water Quality Monitoring: Professors Jennifer A. Jay and William Kaiser have speared a project to improve the detection of enteric bacteria at swimming beaches. This project is entitled “Rapid detection of E.coli and enterococci by immunomagnetic separation and improved ATP quantification for monitoring microbiological water quality in Santa Monica Bay beaches” and involves graduate student Christine M. Lee. Current lab methods for monitoring recreational water quality utilize fecal indicator bacteria (FIB) as proxies for disease-causing organisms and require an incubation step of 18-96 hours. This incubation step makes protective actions such as beach closures delayed and problematic, due to the high variability of FIB concentration in water. A recently developed method for near real-time (< 1 hour) Escherichia coli detection consists of immunomagnetic separation of the target bacteria from the matrix using an antibody-magnetic bead complex followed by ATP detection (IMS/ATP) to quantify the concentration of target bacteria. Luciferin/luciferase (L/L) is added to lysed target cells and its subsequent light emission is measured in Relative Light Units (RLU) by a luminometer; this emission can be correlated to bacterial concentration. Though this method has shown promising results in freshwater, tests in marine water showed low recovery, false negatives, and the need for further method optimization and development. The PIs have made significant modifications in the method for E. coli that have improved the method recovery in seawater, and we are currently developing the method for enterococci. The PIs have constructed a novel, improved light detection system to replace the luminometer, consisting of a photomultiplier tube that yields results as a function of time in standard units (Watts). This alteration allows the flash and glow stages of the reaction to be distinguished. Comparisions are underway comparing this rapid detection method alongside standard culture methods at three beaches in Santa Monica Bay, CA. Advantages of this method are that it is viability-based (as opposed to PCR-based tests), near real-time, sensitive, and adaptable to specific pathogens.

Laboratory experiments: The laboratory component of the Networked Aquatic Microbial Observing Systems project has focused on methodological approaches for examining the vertical distribution or microorganisms in a water column (with the intent of eventual application in the field. Our recent work has focused on the dinoflagellate Lingulodinium polyedrum. This alga is a major contributor to red tides within the Southern California Bight off our west coast (Fig. 18, lower right). Massive aggregations of the alga have implicated swimming behavior of the dinoflagellate (specifically, daily vertical migration) as a fundamental factor affecting these aggregations. We have examined the importance of this behavior in the formation of red tides of the dinoflagellate L. polyedrum in our laboratory water column.

Experiments were conducted using our water column, and applying a newly developed genetic detection/enumeration approach based on the application of quantitative real-time PCR. High-resolution vertical profiling of the dinoflagellate population throughout the course of a 24-hour period have indicated that diel (daily) vertical migration plays an important role in the development of massive aggregations of this red tide alga.

Figure 18. Spatial (vertical) distributions of Lingulodinium polyedrum in our laboratory testbed water column. Note distinct diel pattern to the vertical position of the alga. Brown discoloration at the surface of the water column (bottom left) indicates massive accumulation of algae near the surface during the day. Light microscopy (bottom right) of the red tide dinoflagellate.

Future Directions

Our primary accomplishment during the past year has been the performance of an extensive field program to deploy NAMOS in Lake Fulmor at the James Reserve. The specific accomplishments (noted above) were aimed at the improvement of embedded networked sensors include (1) full coordination between the static sensor nodes (buoys) and the autonomous vehicle (robotic boat) to enable within-network decisions on boat navigation, sensing and sampling, (2) multiscale sensing/sampling using the buoys, and in coordination with the robotic boat, (3) build-out and integration into the network of a new robotic boat (and/or buoy) that possesses the ability to profile vertically within the water column (including enabling sample collection at specified depths, (4) collection, comparison and integration of multi-scale sensed data, and (5) actuated sampling (adaptive sampling) aimed at identifying discrete biological features in time and/or space.

King Harbor, City of Redondo Beach: We have now begun to exploit the progress from our Lake Fulmor campaigns in development of the sensor network and coordinated autonomous vehicle activities to begin a new research program in King Harbor in the City of Redondo Beach. Southern Californian coastal waters have recently witnessed deadly algal blooms and the appearance of previously undocumented species of harmful algae in local waters. These events have impacted endangered and protected wildlife species, and have been documented in a variety of media outlets ranging from local newspapers to national television (see list of news coverage below). Related to the issue of HABs, biological contamination of swimming beaches of the Southern California Bight is presently under tremendous scrutiny. Urbanized coastal beaches often receive poor grades from environmental advocacy groups as a consequence of the presence of unacceptable levels of bacterial species that are indicators of fecal contamination. Beach closures, reduced tourism, and human illness as a result of exposure at the beach result in the loss of untold millions of dollars annually.

A major unanswered question regarding the recent increase of HABs and other contamination events in this region is how human activities on land play a role in the occurrence and/or severity of these events. Anthropogenic sources of nutrients and contaminants may contribute to algal blooms and other environmental problems along our highly urbanized coastline where land runoff, river discharge, sewage outfalls and storm drains constitute multiple point potential sources. The relative importance of anthropogenic sources of contaminants, relative to natural sources of nutrients, for the proliferation and intensification of these phenomena is not clear to science at this time.

A major problem with characterizing pollution in harbors and beaches is the emphemeral nature of these events, and the factors leading to them. Because of the episodic nature of nutrient input to coastal waters (e.g. storm drain and river discharge during sporadic rainfall events in southern CA), it is difficult to link cause-and-effect for many environmental problems. Networks of sensors that monitor environmentally pertinent parameters provide continuous ‘presence’ in aquatic ecosystems that can greatly improve our ability to identify short-term and/or small-scale changes in nutrient sources and other contaminants. These instruments provide information on a variety of chemical and physical parameters that can be used to interpret overall water quality, help determine the sources and magnitude of contaminants, and identify imminent or emerging events.

Pseudo-nitzschia & Domoic Acid in Coastal Waters of the Southern California Bight:

Diatoms in the genus Pseudo-nitzschia are recognized worldwide as potential producers of domoic acid (DA), a water-soluble neurotoxin that accumulates in filter-feeding organisms (most notably shellfish and planktivorous fish such as anchovy) in the presence of toxic Pseudo-nitzschia cells. Humans consuming seafood (typically shellfish) contaminated with DA experience Amnesic Shellfish Poisoning (ASP) whose symptoms may include vomiting, confusion, memory loss, coma or even death. In natural marine food webs, DA poisoning has resulted in significant mortality to species consuming fish or shellfish that have concentrate the toxic diatoms, most notably populations of seabirds and marine mammals.

DA poisoning has resulted in large-scale toxic events in marine animal populations along the west coast of the U.S.. Most recently, these harmful algal blooms have been noted within the Southern California Bight near Los Angeles (Schnetzer et al., 2007). These events have resulted in the death of hundreds of seabirds (including significant number of an endangered species, the Brown Pelican), and thousands of marine mammals (mostly California Sea Lions).

This HAB problem is presently the focus of a research program involving a subset of CENS faculty. The program is funded through the Monitoring and Event Response for Harmful Algal Blooms (MERHAB) program of the National Oceanic and Atmospheric Administration. A primary research objective of this project is design and implement a ‘NAMOS-type’ sensor network that will be used to characterize the distribution and activity of phytoplankton that produce domoic acid. An autonomous vehicle (a submersible glider), will be used as the mobile robotic vehicle whose activities will be directed using information streaming from the stationary sensor nodes. This work represents an important environmental problem for the development and application of our environmental sensor network, and the first ‘large scale’ buildout of our sensor network approach. The program involves formal and informal collaborators from several universities, research institutions and government agencies.