Quantity and Quality of Light on Growth and Pigment Content of <i>Dunaliella</i> sp. and <i>Anabaena</i> sp. Cultures and the Use of Their Absorption Spectra as a Proxy Method for Assessment

(1) Background: As microalgae cultures are affected by the quantity and quality of light, I explored this for two species. Additionally, I introduced a novel easy and economical way for the growers to easily and economically ascertain continuously with satisfactory accuracy the quantitative and qualitative status of their culture using absorption spectra. (2) Methods: The locally isolated chlorophyte Dunaliella sp. and the cyanobacterium Anabaena sp. were cultured in small volumes with two intensities of white light (2000 and 8000 lux) and with green, blue and red light, and the increase in their biomass and pigments was studied. Pigment analyses, continuous recordings of absorption spectra and calibration curves were used. (3) Results: The intensity of 8000 lux of white light yielded the highest increase in biomass, chlorophylls and carotenoids in Dunaliella sp., and the same was found for green and blue light, while 2000 lux and green light caused the greatest increase in biomass and phycocyanin in Anabaena sp. From the absorption spectra, the evolution of the pigment content can be estimated, and both pigments and biomass are correlated very strongly with those extracted from the spectra absorption of 750 nm. (4) Conclusions: The use of absorption spectra as an easy, fast and economical method can be a useful tool for a good approximation of the state of the microalgae culture. This is clearly shown when the spectra of the cultures under different light intensities and colors are compared having a catalytic effect on the level of the pigments leading to the increase in carotenoids and phycocyanin of the green light

Age and growth of the golden grey mullet Liza aurata (Actinopterygii: Mugiliformes: Mugilidae), in the Messolonghi-Etoliko Lagoon and the adjacent Gulf of Patraikos, Western Greece

Background. The fisheries of the Greek lagoons is based on the seasonal fish migration from coastal areas to the lagoon and the summer-to-winter offshore fish migration. The knowledge of the age and growth of the species in the two connected regions is essential for the proper management of the resources. The aim of this study was to estimate the age and growth of Liza aurata in the Messolonghi-Etoliko Lagoon system and the neighbouring coastal waters of the Gulf  of Patraikos (Western Greece). Materials and methods. From December 1992 to February 1994, a total of 1146 individuals of Liza aurata were caught in the Klisova Lagoon (part of the lagoon complex of Messolonghi-Etoliko) and their adjacent sea coastal area, using barrier fish traps, seine, and trammel nets.  The fish age was determined from scale readings. Back calculated lengths at age, as derived using scales readings, were used to estimate the growth parameters of von Bertalanffy equation. The length–weight relation was estimated by the equation: W = a · Lb. Results. The total length (L) of examined specimens ranged from 9.7 to 59 cm. The scale readings revealed nine age classes in the Gulf of Patraikos (0 to VIII) and seven (0 to VI) in the lagoon. Maximum age was found to be 8 and 6 years for females and males, respectively. The analysis of the residuals sum of squares showed that the VBGF curves of sexes between the Patraikos sea area and the lagoon were not significantly different (sexes: F = 0.51, P > 0.05 and regions: F = 0.46, P > 0.05, respectively). The estimated values of VBGF for all samples were L¥ = 65.08 ± 2.61 cm; k = 0.149 ± 0.017 year–1 and to = –1.15 ± 0.063 year. No significant difference on the length–weight relations among the sexes was found (F = 3.15, P > 0.05) while a significant difference on the length–weight relations among the regions (sea: W = 0.0036L3.26; lagoon: W = 0.0057L3.13) was found (F = 21.1, P < 0.05) which reproduced a rather low difference (<±5%) along the size (weight) of species. The length–weight relations exhibited allometry. Conclusion. The age and growth in length and weight of Liza aurata in the lagoon system of Messolonghi-Etoliko and the neighbouring seawaters of Gulf of Patraikos were not significantly different. This could be explained by the fact that the relative high salinity situation of the lagoon may rebut their high trophic advantage for the fish and/or alternatively, by a scenario that is based on the seasonal migrations of species between sea and lagoon

Response of the Ciliates Fabrea salina and Condylostoma sp. to Different Salinities and Microalgal Feeds

In the quest of finding local strains of marine ciliates that can be easily cultured under a broad range of salinity and fed with microalgae, Fabrea salina Henneguy, 1890 and Condylostoma sp. Bory de St. Vincent, 1826 were cultured for 22 days in small volumes at a temperature of 16&ndash;18 &deg;C and fed with flagellated microalgae. F. salina presented a clear preference for the salinity of 40 ppt and Condylostoma. sp. for 20 ppt. Rhodomonas salina Hill and Wetherbee, 1989 were the most efficient feeds, resulting in 30 ind./mL in F. salina and 73 ind./mL in Condylostoma. Dunaliella salina Teodoresco, 1905 and Nephroselmis sp. F. Stein, 1878 also resulted in considerable ciliate densities while Isochrysis galbana Parke, 1949 came last with the highest density in Condylostoma. The strain of Tetraselmis sp. F. Stein, 1878 (var. red pappas) which is transformed in immobilized palmelloid cells and the dinoflagellate Amphidinium carterae Hulburt, 1957, which is suspected of toxin production, were inappropriate for both ciliates. These ciliates can be easily cultured and can serve as useful organisms in bioassays and probably as live food in marine fish hatcheries

The Effect of Various Salinities and Light Intensities on the Growth Performance of Five Locally Isolated Microalgae [Amphidinium carterae, Nephroselmis sp., Tetraselmis sp. (var. red pappas), Asteromonas gracilis and Dunaliella sp.] in Laboratory Batch Cultures

After a 1.5-year screening survey in the lagoons of Western Greece in order to isolate and culture sturdy species of microalgae for aquaculture or other value-added uses, as dictated primarily by satisfactory potential for their mass culture, five species emerged, and their growth was monitored in laboratory conditions. Amphidinium carterae, Nephroselmis sp., Tetraselmis sp. (var. red pappas), Asteromonas gracilis, and Dunaliella sp. were batch cultured using low (20 ppt), sea (40 ppt), and high salinity (50 or 60 or 100 ppt) and in combination with low (2000 lux) and high (8000 lux) intensity illumination. The results exhibited that all these species can be grown adequately in all salinities and with the best growth in terms of maximum cell density, specific growth rate (SGR), and biomass yield (g dry weight/L) at high illumination (8000 lux). The five species examined exhibited different responses in the salinities used, whereby Amphidinium clearly performs best in 20 ppt, far better than 40 ppt, and even more so than 50 ppt. Nephroselmis and Tetraselmis grow almost the same in 20 and 40 ppt and less well in 60 ppt. Asteromonas performs best in 100 ppt, although it can grow quite well in both 40 and 60 ppt. Dunaliella grows equally well in all salinities (20, 40, 60 ppt). Concerning the productivity, assessed as the maximum biomass yield at the end of the culture period, the first rank is occupied by Nephroselmis with ~3.0 g d.w./L, followed by Tetraselmis (2.0 g/L), Dunaliella (1.58 g/L), Amphidinium (1.19 g/L), and Asteromonas (0.7 g/L) with all values recorded at high light (8000 lux)

Response of the Ciliates <i>Fabrea salina</i> and <i>Condylostoma</i> sp. to Different Salinities and Microalgal Feeds

In the quest of finding local strains of marine ciliates that can be easily cultured under a broad range of salinity and fed with microalgae, Fabrea salina Henneguy, 1890 and Condylostoma sp. Bory de St. Vincent, 1826 were cultured for 22 days in small volumes at a temperature of 16–18 °C and fed with flagellated microalgae. F. salina presented a clear preference for the salinity of 40 ppt and Condylostoma. sp. for 20 ppt. Rhodomonas salina Hill and Wetherbee, 1989 were the most efficient feeds, resulting in 30 ind./mL in F. salina and 73 ind./mL in Condylostoma. Dunaliella salina Teodoresco, 1905 and Nephroselmis sp. F. Stein, 1878 also resulted in considerable ciliate densities while Isochrysis galbana Parke, 1949 came last with the highest density in Condylostoma. The strain of Tetraselmis sp. F. Stein, 1878 (var. red pappas) which is transformed in immobilized palmelloid cells and the dinoflagellate Amphidinium carterae Hulburt, 1957, which is suspected of toxin production, were inappropriate for both ciliates. These ciliates can be easily cultured and can serve as useful organisms in bioassays and probably as live food in marine fish hatcheries

Salinity Tolerance and the Effect of Salinity and Algal Feed on the Demographics of Cultured Harpacticoid Copepods <i>Tisbe holothuriae</i> and <i>Tigriopus</i> sp. from the Messolonghi Lagoon (W. Greece)

The locally isolated harpacticoid copepods Tigriopus sp. and Tisbe holothuriae were subjected to salinity tolerance experimentation at salinities under and above of 40 ppt, and presented high halotolerances in Tigriopus LC50 (24 h) of 1 ± 4.43 ppt and 132 ± 5.35 ppt, respectively, and in Tisbe of 15 ± 2.41 ppt and 93 ± 3.23 ppt, respectively. Tetraselmis suecica, among other microalgal feeds (Asteromonas gracilis, Rhodomonas salina, Dunaliella salina and Isochrysis galbana), resulted in the higher production of nauplii in Tigriopus and R. salina and D. salina in Tisbe (also close to T. suecica in Tigriopus). The demographics (number of nauplii, egg sacs, completion of hatching) of both copepods, using combinations of salinities in the range of 22–60 ppt and D. salina and R. salina as feeds, exhibited almost the same preference for microalgae but were negatively affected by the salinity of 60 ppt. The present experiments showed that these local copepods that have extreme salinity tolerance and a wide preference for easily cultured microalgae can be used in ecological studies and for mass production as live feed in marine fish hatcheries

The Effect of Salinity and Light Intensity on the Batch Cultured Cyanobacteria Anabaena sp. and Cyanothece sp.

On the quest of discovering novel local strains of microalgal species that can be effectively cultured with industrial perspectives, two cyanobacterial strains Anabaena sp. and Cyanothece sp. were isolated from the lagoonal and saltworks waters of the Messolonghi lagoon (W. Greece). They were batch cultured at 20&ndash;21.5 &deg;C in six combinations of three salinities (20, 40 and 60 ppt) and two light intensities (2000 and 8000 lux) resulting in: (a) Anabaena grew best at 20 and 40 ppt at high light of 8000 lux. (b) Cyanothece grew best at 40 and 60 ppt at high light. (c) Low light of 2000 lux resulted in much reduced growth in all treatments. (d) Maximal biomass yield was 1.27 and 1.77 g d.w./L for Anabaena and Cyanothece, respectively. Overall, both species have culture potential yielding biomass comparable to the average (or above) relevant values reported in the literature for various cultured cyanobacteria

1 Introduction Are Virtual Machine Monitors Microkernels Done Right?

opinion that the academic obsession with microkernels during the past two decades produced many publication