In this issue of TD News, I am excited to announce our newest instrument, the Trilogy™ Laboratory Fluorometer. It's a unique and dynamic laboratory fluorometer with absorbance and turbidity capabilities. We are eager to open up a new realm of applications with the absorbance functionality while maintaining the accuracy and efficiency of our long-standing product line.

We hope you enjoy this edition of TD News. We are always interested in hearing from you; please do not hesitate to contact us with feedback on the newsletter or our products and services.

Yours truly,
Chelsea Donovan
Environmental Marketing Manager

Introducing the new Trilogy™ Laboratory Fluorometer

Trilogy™ is a compact, multifunctional laboratory instrument that uses snap-in Application Modules to measure fluorescence, absorbance and turbidity. Trilogy™ features a Touch-Panel graphics user interface for intuitive operation and calibration. The Trilogy™ can store up to eighteen named calibrations for various applications.

The standard Fluorescence Modules are available for chlorophyll a, (extractive acidification and non-acidification plus in vivo), rhodamine and fluorescein dye, cyanobacteria (phycocyanin and phycoerythrin pigments), CDOM and ammonium. For extracted chlorophyll measurements using EPA 445, Trilogy™ automatically calculates the concentration. Customers are also able to order custom filter configurations for additional applications.

The Turner Designs Turbidity Module uses an Infra Red (IR) LED with a wavelength of 860nm to meet ISO 7027 requirements for turbidity water quality measurements. Turbidity is "an expression of the optical property that causes light to be scattered and absorbed rather than transmitted in straight lines through a sample" (Standard Methods, 1995). As light passes through "pure" water, the light beam travels along relatively undisturbed paths. When light passes through a fluid containing suspended solids, the light beam interacts with the particles, and the particles absorb the light energy and re-radiate light in all directions. Due to particle size interference and concentration affects, turbidimeters measure the scatter of light at a 90 degree angle to the incident beam. Common turbidimeters use incandescent lamps (polychromatic) with wide spectral bands that include many wavelengths. Natural color and organic matter in a sample can absorb specific wavelengths and reduce the intensity of scattered light introducing interference. Turner Designs uses a monochromatic IR LED, which have narrow band light wavelengths. The narrow bandwidth of the IR LED is less susceptible to natural color and organic matter reducing interference. A photodetector detects the light produced from the interaction of the incident light and the sample volume and produce an electronic signal that is then converted to a turbidity value.

The Turner Designs Absorbance Module allows the user to install filter paddles with varying wavelengths to measure specific compounds. The Absorbance Module utilizes the Beer-Lambert law (Beer's law) which is the linear relationship between absorbance and concentration of an absorbing species.
The Beer's law is usually written as: A = a(l)*b*c
A = Measured absorbance
a(l) = Wavelength-dependent absorptivity coefficient
b = Path length
c = Analyte concentration
Measurements are also reported as transmittance (T).
T = I/Io
I= Intensity of light after it passes through the sample
Io = Initial light intensity

The Trilogy™ currently offers Absorbance Modules with filter paddles of 560/10, 600/10, and 750/10nm. The Absorbance Modules can be configured for various colorimetric applications that can be determined with a single wavelength.

Turner Designs Spreadsheet Interface Software is included to provide real time display and logging of data to an Excel spreadsheet. For more information about the Trilogy™ Laboratory Fluorometer please visit our website or contact our sales department.

SCUFA Used for HAB Monitoring Off South African Coast

The Benguela system suffers from frequent occurrences of a variety of toxic and otherwise harmful algal blooms (HABs). Such blooms can have severe negative impacts on local marine ecosystems and communities. The mooring has been constructed as part of a BCLME (Benguela Current Large Marine Ecosystem) project to demonstrate the utility of real time bio-optical data as an integrated management tool for coastal agencies, and an early warning system with regard to HAB detection and ecosystem protection.

The mooring is deployed on the southern Benguela Namaqua shelf, three and a half kilometers offshore from Lamberts Bay. This area is subject to frequent occurrences of HABs, predominantly composed of dinoflagellate and ciliate species. The buoy has been deployed here as research in the region is ongoing and the area is perhaps the most studied and well understood region of the Benguela system with regard to the dynamics, formative mechanisms and typical assemblage structure of harmful algal blooms.

trial mooring

The buoy provides real time ocean colour reflectance, temperature and fluorescence data transmitted using cell phone telemetry. Considerations in the design of the mooring were that it should be cost-effective and robust whilst minimising shading of the optical sensors and allowing for field calibration and deployment from small vessels.

The trial mooring was deployed off Lamberts Bay from February to June 2004 providing a unique data set of hyperspectral reflectance measurements and ancillary data relating to algal bio-mass and water column structure.

A second buoy has subsequently been developed utilising a pencil buoy design on a two anchor tight line mooring for enhanced sea-keeping abilities. It was deployed in the same position as the trial mooring off Lamberts Bay in January 2005.

The instrument package on the buoy consists of two TriOS hyperspectral radiometers (one radiance, one irradiance), a 50m Templine thermistor chain, a SCUFA fluorometer and an RD Instruments ADCP. Power management, data acquisition and storage and data transmission are controlled by a Saturn Solutions Ocean-i Sensor Unit. The buoy is powered by a 12Ah gel lead acid battery, which is charged by solar panels. A GPS unit provides position information and accurate time to Ocean-i . An inclinometer incorporated into the radiance sensor allows for quality control of the data.

Data are collected from all the instruments simultaneously for two minutes every half an hour. These data are stored on a Compact Flash card in the Ocean-i Sensor Unit. Data are retrieved from the buoy by dialing into the buoy from an external modem. This process is automated at the University of Cape Town so that the most recent data acquisition is downloaded four times a day. Data are then processed using Matlab - remote sensing reflectance is calculated from the radiometer data and locally developed reflectance algorithms are applied to the data to calculate algal biomass and effective assemblage size. The website is updated with these data twice daily when data are available.

This article is from the Harmful Algae Blooms in South Africa website (http://www.hab.org.za) which is intended as a resource for information and data related to harmful algal blooms in the Benguela system. It is a joint effort between the University of Cape Town, Marine and Coastal Management and the Benguela Current Large Marine Ecosystem (BCLME) programme.

Question:
How does changing the basic operating level adjust the sensitivity of the 10-AU?

Answer:
When you go through the steps of setting the basic operating level on the 10-AU you are setting the sensitivity of the instrument. If the set screw is loosened and the sensitivity adjustment knob is turned, it rotates an internal shaft that has a "pie shaped" piece of polarizer connected to it. Light that is emitted from the lamp is partially diverted through a corresponding piece of polarizer. This piece of polarizer is attached in a fixed position on the light pipe. The light pipe provides feedback to the photomultiplier tube(PMT). The PMT is an electronic device that collects and registers the fluorescence that is emitted from the sample. As the sensitivity screw is turned, the shaft rotates and the polarizer changes orientation between the light pipe and the lamp, causing an increase or decrease in the amount of reference light collected by the photomultiplier tube. If the polarizers allow more light transmission to the PMT the sensitivity will be decreased. Conversely, if the position of the polarizing filters allow less light to travel through the light pipe, it will cause higher sensitivity. A good way to think about it is, if there is less light (more polarizer effect), it becomes easier to take smaller(lower concentrations) readings of fluorescence. The basic operating level of the 10AU should be readjusted any time the optics or the application has changed. The picture below illustrates the location of the polarizers, set screw and sensitivity adjustment knob.

Investigating the Carrying Capacity of the Menai Strait in Terms of Mussel Aquaculture

University of Wales, Bangor School of Ocean Sciences

Background
The School of Ocean Sciences (University of Wales, Bangor) is one of the largest university ocean science teaching centres in Western Europe, and its research activities include the principal fields of marine biology, chemistry, geology and physics, as well as a strong emphasis on inter-disciplinary research. The School of Ocean Sciences is based on the shores of the Menai Strait, between the Isle of Anglesey and the UK mainland. The area is considered a location of outstanding beauty and it is expected the Menai Strait and its shores will soon become a Marine Nature Reserve.

Among many of the projects undertaken at the School, several PhD.-studentships are since October 2004 being conducted through the help of the European Social Fund (ESF). These studentships are always linked to a Small/Medium-sized Enterprise (SME) located in so-called "Objective 1 areas" in Wales. Under its policy to "promote harmonious development" within its boundaries, the European Union (EU) aims to specifically "narrow the gap between the development levels of the various regions". Hence, the EU is supporting development in these less prosperous regions. Under these missives, the ESF-funded projects, through training people and businesses in the Objective 1 regions, aim to increase employment and investment in the region.

Myti Mussels Ltd was established in Bangor in 1982. The cultivation of mussels had been practised in the Menai Strait since the late 1950's, but had gone into decline. By investing in new vessels and adopting new techniques, this decline was reversed and the Menai Strait is now the leading production area for mussels in the entire U.K. The company operates two vessels and farms some 120 Ha with annual production levels ranging from 2400 to 8000 tonnes. All this production is exported live to the continent for further processing.

Application Introduction
With help from the European Social Fund and Myti Mussels Ltd., a PhD.-research studentship is being undertaken to investigate the carrying capacity of the Menai Strait in terms of mussel aquaculture. The Menai Strait lies in North Wales between mainland Britain and the Isle of Anglesey. The hydrodynamics of the region are strongly influenced by the tidal regime, and there is a net transport through the Strait in a south-westward direction. Much of the mussel aquaculture is located at the North-eastern end, and it is thought the high mussel production rates that occur, are linked to the advective transport of phytoplankton biomass from Liverpool Bay into the region.

Application Objectives
Using two fluorometer moorings at the North-eastern end, we are hoping to clarify the source of phytoplankton to the region, as the hydrodynamics at this end are further complicated by the presence of large intertidal flats, called Lavan Sands. The use of a differential set-up with fluorometers measuring the concentration before and after the mussel beds, will also hopefully allow us to estimate feeding over the mussel beds, and thus make an indirect estimate of mussel consumption rate and carrying capacity. Close cooperation with the local mussel fishery will allow more direct knowledge of the current and future fishery capacity, as well as regular trips to the mooring sites for cleaning and downloading of the instrumentation.

Figure 1: Moored fluorometer, as deployed in the Menai Strait.

Application Description
At the North-eastern end of the Menai Strait, two moorings have been deployed, each carrying a Turner Designs SCUFA Submersible Fluorometer. Figure 1, shows the set-up of these moored instruments, and Figure 2 shows their location. These instruments are calibrated using in-situ sampling and chlorophyll extractions on a Turner 10 AU Field Fluorometer. The sampling frequency is set at every two minutes, the two SCUFAs being recovered and redeployed every two weeks. At Menai Bridge a monitoring station is measuring the chlorophyll concentration after it has passed over the mussel beds. Using the difference in the chlorophyll concentration results, we will hopefully be able to estimate the current mussel consumption of biomass and make an estimate of the maximum sustainable biomass in light of expansion of the mussel fishery.

Figure 2. Location of fluorometer moorings deployed in the Menai Strait.

Application Results
Currently we are at an early stage in the sampling process, and we have only recently overcome problems in the sampling strategy, including fouling of the sensors over extended deployment periods. The SCUFAs will subsequently be fitted with the Turner anti-fouling screens, which should significantly reduce the accumulation of biofouling. Hence, the results presented here should only be seen as a preliminary outcome of the mooring deployments.

Figure 3 shows the fluorometer signal over a period of two weeks. It can be seen that the chlorophyll concentrations exhibit a strong semi-diurnal pattern. This occurs due to the water being advected over the mussel beds on the ebb tide (convention in the Menai Strait is to call the stage of the tide where currents are flowing to the south-west, i.e. through the Strait, as the ebb tide), and the phytoplankton suspended in the water column is depleted due to mussel feeding. It is then advected back northwards on the flood, where it can be seen the concentration is significantly lower.

Figure 3: Chlorophyll concentrations measured over a two-week period in June in the Menai Strait.

The chlorophyll concentrations also show a greater variability in the signal at the site near the large sand flat area (Penmaen Swatch), compared to the site near the main channel (Penmon Bay). It is thought this is due to the presence of the intertidal area, and the effects it has on the local hydrodynamics. Further research is currently being done in this area, more specifically to clarify the flow environment in this region.

What?
In response for more 'real-world' data from our customers, Turner Designs has launched the TD DataBank Program where we present examples of customer research for all instruments and applications. The DataBank is organized according to instrument type and application and offers our users real-world examples of how researchers and technicians are using Turner Designs instruments in their work. In addition to providing meaningful information for our customers, by having a description of your work highlighted on our website, it will serve as a means of reaching a greater number of scientists around the globe. We see this as a highly effective means of assisting our users in making informed decisions. In order for this type of program to succeed, we need information from you on your application and how a Turner Designs fluorometer is helping you.

How?
We have designed the TD DataBank to make submitting an application summary as easy as possible. The entire process should not take more than 20 minutes. We ask for a brief description of your research, and how you use Turner instruments. Also, a picture or graph of data collected with Turner instruments is requested. To show our appreciation for your data bank articles, we will send you a Turner Designs sports bag. Claim your sports bag now by submitting your DataBank article!

Why?
We hope you will join us in this exciting and useful program by sharing your knowledge and experience with scientists and technicians around the globe. To take part, please visit http://www.turnerdesigns.com/databank/submit_data.html.