Algae species

Alginic acid is a linear polymer composed of (i-1,4-D-mannuronic and L-gulucuronic acid the proportions of the two units are not constant in the alginates from different algae species (Fig. 11). 

The halogenated acyclic marine monoterpenes are often considered to be the biogenetic precursors of the alicyclic monoterpenes that are presented in this section. Many of the preceding algae species also contain cyclic monoterpenes. As was the case in preceding sections only newly characterized compounds are numbered and the reader is referred to the first survey for structures of previously isolated compounds (7). 

The occurrence of toxic algal blooms has increased in the last decades. Not only the nnmber of toxic blooms has mnltiplied and their geographical distribution has spread all over the world, bnt also new toxins and new toxic algae species have been described. Azaspiracids are the most recently identified class of marine toxins present in shellfish. Only known since 1997, azaspiracid and its analognes have awakened both public health concern and scientific interest. 

Dembitsky, V.M., Rezanka, T. Natural occurrence of arseno compounds in plants, lichens, fungi, algae species, and microorganisms. Plant Sci. 165, 1177-1192 (2003)... 

Plants and algae species have also been used as biosensors to detect high concentrations of metals from contaminated aquatic ecosystems. Longterm evaluations of zinc and cadmium concentrations using two species of brown algae were conducted in Sepetiba Bay, Rio de Janeiro, Brazil (Amado Filho et al., 1999). 

In Table 2, the algae species encountered during the experimental period are listed. The code used is the one proposed by Whitton et al. [ 7 ]. Characteristics concerning interference in water treatment are based onKrauter[8] and Palmer[ 9 ]. 

Concerning some counted algae species, linear dimension measurements were performed, using a special measuring grid on the ocular of the microscope. 

As a consequence of the difference in counting technique, a shift of measured algae size to smaller values than those determined by microscopy was observed. With each algae species corresponded a typical particle size distribution plot which could be considered as a fingerprint size distribution of that particular planktonic organism. Various algae species were identified with their... 

Marine lizards usually have ample food, but certain conditions can reduce the availability of algae. In the past, El Nino phenomenon, which causes ocean water around the Galapagos Islands to warm, has killed the algae species that the marine iguana eats. The only algae that survived the event were brown algae, which are toxic to marine iguanas, so many lizards died. El Nino is not a yearly event, however, and in most years lizards feed safely. 

A summary of the freshwater species that have been shown to be suitable for testing in the USA are presented in Table 5.1. Upon review of the available literature it quickly becomes apparent that the majority of toxicity tests performed in the USA use Ceriodaphnia dubia (water flea), Daphnia pulex (water flea), and D. magna (water flea) followed by Pimephales promelas (fathead minnow). The reason for this is that the vast majority of the toxicity tests carried out in the USA are in freshwater. In states (e.g. Washington) where protection of salmon population or other coldwater species is an issue, P. promelas may be replaced by Oncorhynchus my kiss (rainbow trout). Testing carried out on ambient water and sediments to identify toxicants from agricultural run-off often include the green algae species Selenastrum capricornutum (recently renamed, see Table 5.1) (Ank-ley et al., 1990, 1992 SETAC, 1998) as part of the toxicity assessment. 

In the northern part of the Western basin, at 24.6 m water depth, the salinity was 92 ppt and the temperature 13.7 C. The centric diatom Actinocyclus octonarius dominated the assemblage. In total, we observed at that location 33 diatom algae species. The diversity was high (Dmg = 4.8, PIE = 0.73, H = 2). Dinophytes and euglenids were absent. 

The ubiquitous nature of proline-containing peptides results in the common appearance of perhydro-l,4-dioxopyrrolo[l,2-a]pyrazines as a result of metabolic processes, particularly of microorganisms. For example, the diketopiperazines 152 were found to be metabolic products of the algae species Scenedesmus sp. These compounds have also been found in cultures of Sfreptomyces. " Glycyl-L-prolyl diketopiperazine has recently been isolated from the small sea animal Luidia clathrata The anhydrides 152 were not directly formed from the constituent amino... 

Compared with passive radiometric techniques, the fluorosensor methods for phytoplankton have several attractive features which are unique. These include relative insensitivity to daylight or cloudiness, specifity of response to Chi, and the potential for depth profiling using range-gating techniques. On the other hand, they are sensitive to other factors such as energy transfer, water composition, algae species, and sediments [8, 9]. 

A simple and sensitive in situ algae fluorosensor based on fiber optics was described by Lund [13]. It was used for in situ studies of natural sweet water. Excitation spectroscopy of four algae species revealed differences in their excitation spectra, which therefore may yield more specific and more accurate information than data obtained with single-wavelength excitation. 

Concentrations in surface water are around 10 mol 1. Although a number of studies have indicated that the ocean forms an important source for atmospheric CS2, the underlying biochemical cycles still remain poorly understood. CS2 is formed by photochemical reactions (possibly involving precursors such as DMS, DMSP and isothiocyanates). CS2 formation has been observed to occur in bacteria in anoxic aquatic environments and in cultures of some marine algae species. 

Iodine concentrations and chemical species of iodine vary widely between algae species. 

The approach represented by equation (16.3) is difficult to apply if organic matter is not measured in chemical oxygen demand (COD) units. This is a problem, because some measurement techniques (e.g. counting of algae species and conversion to wet mass by an average species-specific volume) do not lead to a natural conversion to chemical oxygen demand units. The approach... 

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