Springer Science and Business Media LLC

Lipid-accumulating microalgae are an emerging feedstock for production of liquid biofuel because of their high biomass and lipid productivity. The potential of the green microalgae, Chlorolobion sp. (BIOTECH 4031) and Chlorella sp. (BIOTECH 4026), for biodiesel production was evaluated by analyzing the effect of nitrogen starvation (0.375–1.500 g L−1 NaNO3) on growth response, oil yield, and fatty acid methyl ester (FAME) profiles of the two algal strains. Maximum biomass yields for Chlorolobion sp. and Chlorella sp. were obtained after 20 days of cultivation using the control medium (1.5 g L−1 NaNO3) with 0.873 g L−1 and 0.757 g L−1, respectively. An increasing trend in the total lipid yield was observed under a nitrogen-starved culture condition (0.375 g L−1 NaNO3). When the amount of nitrate was limited, the mean oil contents of Chlorolobion sp. and Chlorella sp. were 31.61 and 28.77% with lipid productivity of 227.84 and 151.14 mg L−1 day−1, respectively. Nitrogen starvation caused an increase in the lipid yield and a decrease in biomass production of the two microalgae. The FAME profile of the obtained algal biodiesel shows a high concentration of saturated fatty acid (SAFA) and monounsaturated fatty acid (MUFA) methyl esters which are desirable for biodiesel production. The fuel properties of biodiesel from the two microalgae were predicted based on the molecular properties of fatty acid methyl esters using empirical equations showing that the biodiesel properties of the two microalgae satisfied the set specifications of biodiesel standards EN 14214 (European) and ASTM D6751 (American). The quality properties of biodiesel obtained for Chlorolobion sp. were low density (0.89 g cm−3), low kinematic viscosity (2.79 mm2 s−1), cetane number (65.17), and oxidation stability (8.93 h). On the other hand, Chlorella sp. has low density (0.88 g cm−3), low kinematic viscosity (2.78 mm2 s−1), good cetane number (68.79), and oxidation stability (10.44 h). Hence, Chlorolobion sp. (BIOTECH 4031) and Chlorella sp. (BIOTECH 4026) have potential as raw material for production of biodiesel with superior fuel quality.

Migration patterns and habitat use of sub-yearling Chinook salmon during initial ocean entrance is poorly understood. Twenty-five years ago, sub-yearling Chinook salmon were hypothesized to stay close to shore (<5 km). To test this hypothesis we sampled the surf-zone of a southern Oregon dissipative sandy beach throughout the summer of 2006 (06/07–09/29) using a beach seine in 1 m of water depth. We caught 48 sub-yearlings over six dates (07/22 to 09/01). Mean standard length of Chinook salmon caught in the surf-zone increased from 9.1 ± 0.6 (07/22/06) to 11.6 ± 0.7 cm (09/01/06), suggesting a mean increase of 0.6 mm in standard length (S.L.) per day. Early in the summer, smaller fish fed mostly on amphipods. Later in the summer, larger juveniles fed primarily on larval and juvenile fish. All prey items were common in the surf-zone. Juveniles appear to migrate from the estuary to the surf-zone where they feed on the local zooplankton for up to two summer months before migrating offshore.

This paper reports for the first time the transient expression of areporter gene, LacZ, in the unicellular green alga Haematococcuspluvialis. By employing the micro-particle bombardment method,motilecells in the exponential phase showed transient expression oflacZ. This was detected in bombarded motile cells undertherupture-disc pressures of 3103 KPa and 4137 KPa.Transient expression of LacZ gene could not be observed in non-motile cells ofthis alga under the same transformation condition. No LacZ background was foundin either the motile cells or the non-motile cells. The study suggests apromising potential of the SV40 promoter and the lacZreporter gene in genetic engineering of unicellular green algae.

The co-culture of cyanobacteria and heterotrophic bacteria can utilize the advantages of both bacteria, effectively remove pollutants and relieve the feedback inhibition effect in algae culture; however, little information is available in heavy metal removal. In this study, a filamentous cyanobacterium, Leptolyngbya sp. XZ1, isolated from biological soil crusts and four heterotrophic bacterial strains, namely, Y3, Y4, S1 and T2, isolated from the phycosphere were co-inoculated into BG-11 media containing Cd. Amongst co-culture systems, Leptolyngbya + S1 showed the highest Cd removal efficiencies of 93.2%, 71.8%, 60.7%, 56.8% and 41.0% at initial Cd concentrations of 2, 5, 10, 20 and 50 mg L−1, respectively. In this co-culture system, Cd adsorbed on the cell wall was increased by 42.8%, 52.9%, 50.0% and 22.6%, and the intracellular Cd was decreased by 37.9%, 37.0%, 51.0% and 50.6% at initial Cd concentrations of 5, 10, 20 and 50 mg L−1, respectively, compared with the Leptolyngbya monoculture. Under Cd stress, the biomass, extracellular polymeric substances (EPS)-polysaccharides and photosystem II activity of Leptolyngbya sp. XZ1 were increased by co-culture with Bacillus sp. S1. In addition, the Cd stress on Leptolyngbya was alleviated by co-culture with S1 as proven by the superoxide dismutase (SOD) activity, malondialdehyde (MDA) content, scanning electron microscopy (SEM) images, soluble protein content and SDS-PAGE analysis. Results indicated that the cyanobacteria-heterotrophic bacteria co-culture system can be used as an effective bioremediation method to remove heavy metals from aqueous solution.

Lacustrine-adfluvial bull trout, Salvelinus confluentus, migrate from spawning and rearing streams to lacustrine environments as early as age 0. Within lacustrine environments, cover habitat provides refuge from potential predators and is a resource that is competed for if limiting. Competitive interactions between bull trout and other species could result in bull trout being displaced from cover habitat, and bull trout may lack evolutionary adaptations to compete with introduced species, such as lake trout, Salvelinus namaycush. A laboratory experiment was performed to examine habitat use and interactions for cover by juvenile (i.e., <80 mm total length) bull trout and lake trout. Differences were observed between bull trout and lake trout in the proportion of time using cover (F 1,22.6 = 20.08, P < 0.001) and bottom (F 1,23.7 = 37.01, P < 0.001) habitat, with bull trout using cover and bottom habitats more than lake trout. Habitat selection ratios indicated that bull trout avoided water column habitat in the presence of lake trout and that lake trout avoided bottom habitat. Intraspecific and interspecific agonistic interactions were infrequent, but approximately 10 times greater for intraspecific interactions between lake trout. Results from this study provide little evidence that juvenile bull trout and lake trout compete for cover, and that species-specific differences in habitat use and selection likely result in habitat partitioning between these species.

For the first time, growth throughout the life cycle of an annual fish, Cynolebias viarius, was assessed in the wild, within a temporary pool located in eastern Uruguay. Before pools dry out at the beginning of the warm season, C. viarius deposit eggs in the sediment. Embryos hatch when precipitation fills the pools again in March–April. During 1996, at biweekly or monthly intervals, environmental conditions were monitored and the length of 20 to 55 C. viarius measured. Pool size varied between 109 and 475 m2, respectively. Water depth at its center reached between 10 (June) and 35 cm (September). Water temperatures ranged from 6°C in June to 28.8°C in November. The water was slightly acidic (pH = 6.3 ± 0.2) and subsaturated with O2 (48–88%); conductivity averaged 258 ± 39 μS cm−1. On the first field trip after inundation (May 2), mean length of C. viarius was 9.9 ± 1.0 mm. Maximum growth rate (0.66 mm per day) was determined during the following two-week-interval and was associated with relatively high water temperatures (20–22°C). While fish length remained virtually unchanged during the colder winter months, C. viarius manifested growth, specially in weight, during the last third of the life cycle. Fish were sexually mature at 8 (67%) to 18 (100%) weeks of age. In the laboratory, specimens held at 25°C grew faster and reached sexual maturity at an earlier age (11 weeks) than at 15°C (10–16 weeks). Over the 5-months study period, mortality reached 37.5% at 15°C and 100% at 25°C. Results are compared to information available from other annual fishes.