King Harbor in the City of Redondo Beach, California was the site of massive fish kills during 2005 following intense and prolonged red tide events. Weekly monitoring since early 2006 revealed the presence of an abundant and diverse community of potentially harmful dinoflagellate and raphidophyte species in the harbor with highly heterogeneous spatial and temporal distributions. Vertical migration and photoacclimation of dinoflagellates and raphidophytes were investigated as mechanisms for dealing with changing light levels in the King Harbor marina over a 24-hour cycle on 19-20 June 2007. PAR, CTD, chlorophyll fluorescence, dissolved oxygen concentrations, active chlorophyll fluorescence, backscattering, and light absorption and attenuation data were measured every four hours using sensor arrays. Discrete water samples were analyzed for pigment concentrations, particulate and dissolved inorganic nutrients, and phytoplankton community composition using both microscopical and molecular techniques. The overall phytoplankton community composition changed significantly during the 24-hour cycle, and the depth of the chlorophyll maximum moved from shallow waters to deeper depths, and possibly all the way to the sediment interface, during the evening hours. These data suggest a high degree of small-scale heterogeneity in vertical distribution of harmful algal populations and provide important insights into mechanisms that impact community composition within red tide assemblages in King Harbor.

Through the NAMOS project, our team of biologists and engineers are assisting municipalities in understanding the underlying causes and effects of harmful microalgal blooms. Since early 2007, we have been studying system-level dynamics of the chemical, physical, and biological processes in King Harbor, a shallow, semi-enclosed urban harbor in Redondo Beach, California. For the last two years a network of dock-based water quality sensors in the harbor has continuously provided data on the environmental parameters relevant to bloom formation. Additionally, intensive human-mediated studies of the phytoplankton community distribution and structure are testing several hypotheses on the biological and physical factors affecting algal growth in this system. Recent field experiments have sought to explain the roles of tidal forcing and phytoplankton behavior and physiology in the structuring and distribution of bloom-forming algal communities.

Aureococcus anophagefferens, a harmful bloom-forming alga responsible for brown tides in estuaries of the Middle Atlantic U.S., has been investigated by atomic force microscopy for the first time, using probes functionalized with a monoclonal antibody specific for the alga. The rupture force between a single monoclonal antibody and the surface of A. anophagefferens was experimentally found to be 246±11 pN at the load rate of 12 nN/s. Force histograms for A. anophagefferens and other similarly-sized algae are presented and analyzed. The results illustrate the effects of load rates, and demonstrate that force-distance measurements can be used to build biosensors with high signal-to-noise ratios for A. anophagefferens. The methods described in this paper can be used, in principle, to construct sensors with single-cell resolution for arbitrary cells for which monoclonal antibodies are available.

This is a project that aims to expedite research in marine biology using chip-based and state-of-the-art detection technology. The project is a joint effort that will incorporate the expertise of three different groups, Dr. Chih-Ming Ho at UCLA, Dr. David Caron at USC and Dr. Yu-Chong Tai at Caltech. One main focus of the project is to develop Lab-on-a-chip devices that reduce total sample volume and detection time. Also, the chips can be fabricated in large quantities with minimal cost so many experiments can be run in parallel. Here at Caltech, a chip will be developed to culture a small number of algae and screen for factors inducing toxin production. Algal bloom and toxins produced by different algae have always caused problems to the environment and marine ecology. Pseudo-nitzschia is one type of algae that produces a neural toxin called Domoic Acid, which when transferred through the food chain causes sickness and mortality in marine mammals and seabirds. However, during Pseudo-nitzschia bloom, Domoic Acid is not always produced. In another word, growth of algae does not equal Domoic Acid production. Studies done by other groups have suggested that many factors (such as trace metal, macronutrient, or ionic concentration) might induce or suppress algae to produce toxin. Yet, exact causes are unclear. To completely elucidate the causes of toxin production, many potential compounds will have to be screened. This leads to an enormous amount of experiments to be performed and large quantity of reagents and cells to be used. To speed up the process of screening for possible factors inducing toxin production, we would like to make a chip to culture Pseudo-nitzschia under different growing conditions. At the same time, an Ultra Sensitive Electrochemical Sensor will be developed for detection of Domoic Acid at Dr. Chih-Ming Ho’s lab at UCLA. The current state-of-the-art detection technology indicates that per cell toxin load may range over 2 or 3 orders of magnitude but its sensitivity is limited since a sample size of at least 100 cells/mL is required. The new sensor will be able to push the sensitivity to 10 cells/mL or to even single molecules of Domoic Acid. This sensor will not only enable the detection of Domoic Acid produced by algae cells inside the culture chip, such sensor will also have the broad application of detecting Domoic Acid from field samples.

This paper describes the design, development, and initial application of a sensor-actuated network for sensing and sampling microbial communities in aquatic ecosystems. The network consists of ten stationary buoys and one mobile robotic boat for real-time, in situ measurements and analysis of chemical and physical factors governing the abundance and dynamics of microorganisms at biologically relevant spatiotemporal scales. The goal of the network is to obtain high-resolution information on the spatial and temporal distributions of plankton assemblages and concomitant environmental parameters in aquatic environments using the in situ presence afforded by the network and to make possible network-enabled robotic sampling of hydrographic features of interest. This work constitutes advances in (1) real-time observing in aquatic ecosystems and (2) sensor actuated sampling for biological analysis.

Harmful brown tides caused by the pelagophyte Aureococcus anophagefferens have occurred in mid-Atlantic estuaries for 2 decades. Low grazing rates by microzooplankton have been implicated as a possible cause of these events, but no study to date has concurrently quantified zooplankton population densities and zooplankton grazing rates of A. anophagefferens cells. We conducted field studies from 2002 to 2004 to quantify grazing on the brown tide alga A. anophagefferens by meso-, micro-, and nanozooplankton, while concurrently establishing the composition of the plankton community. Research sites included an estuary that experienced an intense brown tide (Chincoteague Bay, Maryland [MD]; 2004: 2 × 10⁶ cells ml⁻¹) and one that experienced sporadic blooms (Quantuck Bay, New York [NY]; 2002: 8 × 10⁵ cells ml⁻¹; 2003 and 2004: × 10⁴ cells ml⁻¹). The MD site was dominated by small autotrophs (µm), such as A. anophagefferens and other picoeukaryotes, and small heterotrophs, such as Paulinella ovalis, while the NY site hosted a range of large and small autotrophs and zooplankton. Experiments indicated that small zooplankton (3 to 5 µm) were consumers of A. anophagefferens at bloom and non-bloom locations. However, dilution experiments documented active grazing on most picoplankton except A. anophagefferens in MD, while grazing rates on the brown tide alga in NY were comparable to grazing rates on the total phytoplankton community and other picoplankton. Experimental enrichment of estuarine waters with mesozooplankton indicated a preferential avoidance of A. anophagefferens by grazers during intense blooms, but active consumption during non-bloom conditions. Differences in the effect of grazing between sites suggest that zooplankton may be controlling brown tides in NY, but allowing blooms to form due to low grazing pressure in MD. These findings further suggest that the zooplankton community in NY has changed from one which formerly avoided the consumption of A. anophagefferens to one which currently contributes to top-down control of brown tides.

Lab-on-a-Chip aquatic microorganism analysis system is a project that aims to expedite research in marine biology using chip-based technology. The miniaturized device reduces the total sample and detection time. Also, the chips can be fabricated in large quantities with minimal cost so many experiments can be run in parallel. Our project is organized into two main research areas. First, we would like to develop a chip to monitor the content of the sea water and assess the concentration of different algae. The chip will take in sea water sample, separate the cells based on size, and a downstream impedance sensor will count the number of cells. The second main area of this project is to make a chip that can culture algae and screen for factors inducing toxin production. The exact causes for Peudo-nitzschia to produce toxins are unclear, and we would like to make a chip that cultures Pseudo-nitzschia under different growing conditions. The algae will be kept inside an array of micro culture chambers and an integrated combinatorial mixer will deliver eight combinatorial streams to the culture chambers. We developed a monolithic process to integrate the combinatorial mixer with culture arrays. The cell culturing functionality and fluidic testing with the chip have been completed. A laser-induced fluorescence detection system is also being developed to be used to detect domoic acid (DA) downstream of the algae culture chip.

Harmful algal blooms (HAB) have been a recurring problem in King Harbor of the City of Redondo Beach in recent years. In 2005, a red tide resulted in a massive fish kill, and created a nuisance for commercial and recreational use of the harbor. It took several weeks for the incident to subside and for the ecosystem to return to normal. Several potentially problematic species of algae again bloomed during 2006, and seven bloom-forming species were isolated and cultured. Beginning in January 2007, the Networked Aquatic Microbial Observing System (NAMOS), which is comprised of both mobile and static sensing platforms, has been employed periodically in the harbor area to monitor phytoplankton population dynamics. A robotic boat is able to provide vertical profiles of critical environmental data including chlorophyll, temperature, salinity and dissolved oxygen throughout the harbor, while continuous recordings of chlorophyll concentration, dissolved oxygen, CTD, and turbidity are gathered by sensors at both surface and near bottom in different locations in the harbor.The combined use of static and mobile nodes constitutes an effective monitoring and early warning system for HABs. NAMOS has proven an excellent tool for providing excellent contextual data for experimental studies of bloom-forming species of phytoplankton. Field and lab experiments were conducted in conjunction with the deployment of the sensor network in order to examine environmental triggers for algal blooms in the harbor.