Maximum Algal Biomass Research Articles

Theoretical Calculations on the Feasibility of Microalgal Biofuels: Utilization of Marine Resources Could Help Realizing the Potential of Microalgae.

Microalgae have long been considered as one of most promising feedstocks with better characteristics for biofuels production over conventional energy crops. There have been a wide range of estimations on the feasibility of microalgal biofuels based on various productivity assumptions and data from different scales. The theoretical maximum algal biofuel productivity, however, can be calculated by the amount of solar irradiance and photosynthetic efficiency (PE), assuming other conditions are within the optimal range. Using the actual surface solar irradiance data around the world and PE of algal culture systems, maximum algal biomass and biofuel productivities were calculated, and feasibility of algal biofuel were assessed with the estimation. The results revealed that biofuel production would not easily meet the economic break‐even point and may not be sustainable at a large‐scale with the current algal biotechnology. Substantial reductions in the production cost, improvements in lipid productivity, recycling of resources, and utilization of non‐conventional resources will be necessary for feasible mass production of algal biofuel. Among the emerging technologies, cultivation of microalgae in the ocean shows great potentials to meet the resource requirements and economic feasibility in algal biofuel production by utilizing various marine resources.

Effects of eutrophication on maximum algal biomass in lake and river ecosystems

To further clarify empirical relationships between maximum phytoplankton biomass per unit total phosphorus (TP) and the maximum:mean phytoplankton biomass ratio, predictive models were created from a meta-analysis of datasets from lakes worldwide. Peak concentrations of planktonic chlorophyll a were on average 2.6 times greater than the mean, with most maximum:mean chlorophyll a ratios falling within less than an order-of-magnitude band (from 1.2 to 6 times the mean value). Peak concentrations of planktonic algal biovolume in 22 Organisation for Economic Co-operation and Development (OECD) lakes were on average 3.3 times greater than the mean, with maximum:mean biovolume ratios ranging from 1.2 to 6.3. By contrast, the temporal dynamics of planktonic (suspended) algal biomass in Minnesota streams and rivers were far more constrained; peak concentrations of planktonic chlorophyll a were only on average 1.8 times greater than the mean, with maximum:mean chlorophyll a ratios ranging from 1.3 to 3.8. These data suggest regional differences in maximum chlorophyll a values may exist. Parallel analyses of periphyton biomass in streams and rivers showed far greater variability in the maximum:mean chlorophyll ratio for benthic algae. Peak concentrations of attached chlorophyll a were on average 4.3 times greater than the mean, with the observed maximum:mean chlorophyll a ratios exhibiting exceptionally high variability (ranging from 1.0 to 50 times the mean value), likely reflecting differences in the temporal dynamics of planktonic and benthic algal growth in freshwater ecosystems.

Effect of wastewater-borne bacteria on algal growth and nutrients removal in wastewater-based algae cultivation system

Centrate, a type of nutrient-rich municipal wastewater was used to determine the effect of wastewater-borne bacteria on algal growth and nutrients removal efficiency in this study. The characteristics of algal and bacterial growth profiles, wastewater nutrient removal and effect of initial algal inoculums were systematically examined. The results showed that initial algal concentration had apparent effect on bacterial growth, and the presence of bacteria had a significant influence on algal growth pattern, suggesting symbiotic relationship between algae and bacteria at the initial stage of algae cultivation. The maximum algal biomass of 2.01g/L with 0.1g/L initial algal inoculums concentration can be obtained during algae cultivation in raw centrate medium. The synergistic effect of centrate-borne bacteria and microalgae on algae growth and nutrient removal performance at initial fast growth stage has great potential to be applied to pilot-scale wastewater-based algae wastewater system cultivated in continuous or semi-continuous mode.

Limnological characteristics and trophic state of Paso de las Piedras Reservoir: An inland reservoir in Argentina

AbstractThe current trophic status of Paso de las Piedras Reservoir was evaluated by analysing different physicochemical, biological and environmental variables, in relation to its water quality, and application of two different classification criteria. Water quality sampling was conducted at four sampling sites from June 2004 to June 2005. During this study, 183 phytoplankton taxa were identified. The phytoplankton abundance exhibited a maximum of 368.037 × 103 cells.mL−1 in February 2005, and at least 1.133 × 103 cells.mL−1 in October 2004. An almost exclusive dominance of Cyanobacteria was observed between December 2004 and May 2005, the product of a large relative abundance of Anabaena circinalis and Microcystis natans which, together with other companions, were the reason for an algal bloom characterized by an average density of 133.05 × 103 cells.mL−1, and an average chlorophyll concentration of 28.7 mg.m−3. These study results indicate that the seasonal variations of physical, chemical and biological parameters in the waters of this reservoir were essentially a consequence of environmental and hydrological conditions in the dam area. In contrast, the spatial variations inside the lake were the result of the characteristics of the water inflow provided by its two main tributaries. The N:P ratio suggests neither nutrient is a limiting factor for maximum algal biomass in the lake, indicating that variations in the phytoplankton community structure, and development of phytoplankton blooms, would be more constrained by environmental and hydrological conditions than nutrient competition. The high concentration of measured nutrients could be attributed to the concurrence of various non‐point sources. The phytoplankton species richness was high, exhibiting values even higher than those mentioned in previous studies. Considering the two trophic classification systems, and based on total phosphorus data, the reservoir is classified within the hypertrophic category. In contrast, considering only the chlorophyll and turbidity data, the lake would be classified within the eutrophic category.

Seasonal feeding strategies of Calanus in the high-Arctic Svalbard region

Abstract The feeding strategies of Calanus hyperboreus, C. glacialis, and C. finmarchicus were investigated in the high-Arctic Svalbard region (77–81 °N) in May, August, and December, including seasons with algal blooms, late- to post-bloom situations, and unproductive winter periods. Stable isotope and fatty acid trophic marker (FATM) techniques were employed together to assess trophic level (TL), carbon sources (phytoplankton vs. ice algae), and diet of the three Calanus species. In addition, population development, distribution, and nutritional state (i.e. storage lipids) were examined to estimate their population status at the time of sampling. In May and August, the vertical distribution of the three Calanus species usually coincided with the maximum algal biomass. Their stable isotope and fatty acid (FA) composition indicated that they all were essentially herbivores in May, when the algal biomass was highest. Their FA composition, however, revealed different food preferences. C. hyperboreus had high proportions of 18:4n3, suggesting that it fed mainly on Phaeocystis, whereas C. glacialis and C. finmarchicus had high proportions of 16:4n1, 16:1n7, and 20:5n3, suggesting diatoms as their major food source. Carbon sources (i.e. phytoplankton vs. ice algae) were not possible to determine solely from FATM techniques since ice-diatoms and pelagic-diatoms were characterised by the same FA. However, the enriched δ13C values of C. glacialis and C. finmarchicus in May indicated that they fed both on pelagic- and ice-diatoms. Patterns in absolute FA and fatty alcohol composition revealed that diatoms were the most important food for C. hyperboreus and C. glacialis, followed by Phaeocystis, whereas diatoms, Phaeocystis and other small autotrophic flagellates were equally important food for C. finmarchicus. During periods of lower algal biomass, only C. glacialis exhibited evidence of significant dietary switch, with a TL indicative of omnivory (mean TL=2.4). Large spatial variability was observed in population development, distribution, and lipid store sizes in August. At the northernmost station at the southern margin of the Arctic Ocean, the three Calanus species had similarly low lipid stores as they had in May, suggesting that they ascended later in the year. In December, relatively lipid-rich specimens had TL similar to those during the peak productive season (TL≈2.0), suggesting that they were hibernating and not feeding on the available refractory material available at that time of the year. In contrast, lipid-poor specimens in December had substantially high TL (TL=2.5), suggesting that they were active and possibly were feeding.

다공질 인공어초 (반톱니형)에서 진행된 해조천이 및 해중림 조성

The succession of marine benthic algae and the restoration of an artificial seaweed forest on a porous type (shaped half saw teeth) artificial reef at Jeju island, Korea was studied. Young thalli of Sargassum horneri and Ecklonia cava were attached to different artificial substrates. In general, the succession on the artificial reefs led from filamentous algae to perennial algae and involved more than 25 species that are useful fishery resources, including E. cava. Coralline algae were dominant on the artificial reefs at the Kangjung site. The maximum algal biomass on the artificial reef in October 2005 was <TEX>$1,990g/m^2$</TEX> at Biyang. In conclusion, a climax community and seaweed forest can be attained one year after the substrate is constructed.

Competition between macroalgae and corals: effects of herbivore exclusion and increased algal biomass on coral survivorship and growth

Recent declines in coral abundance accompanied by increases in macroalgal cover on Florida reefs highlight the importance of competition for space between these groups. This paper documents the frequency of coral–algal interactions on the Northern Florida Reef Tract and evaluates the effects of grazer exclusions and experimental algal addition on growth and tissue mortality of three coral species, Siderastreasiderea, Poritesastreoides, and Montastraeafaveolata. The frequency of interactions between corals and macroalgae was high as more than 50% of the basal perimeter of colonies was in contact with macroalgae; turf forms, Halimeda spp., and Dictyota spp. were the most common groups in contact with corals. Decreased grazing pressure resulted in significant increases in algal biomass within cages, and caged corals showed species-specific susceptibility to increased algal biomass. While no effects were detected for S. siderea, significant decreases in growth rates were documented for caged P. astreoides which had growth rates three to four times lower than uncaged colonies. When an algal addition treatment was included to duplicate maximum algal biomass levels documented for reefs in the area, colonies of P. astreoides in the algal addition treatment had growth rates up to ten times lower than uncaged colonies. High susceptibility to algal overgrowth was also found for the reef-building coral M. faveolata, which experienced significant tissue mortality under both uncaged (5.2% decrease in live tissue area per month) and caged (10.2% per month) conditions. The documented effects of increased algal biomass on coral growth and tissue mortality suggest a potential threat for the long-term survivorship and growth of corals in the Florida Reef Tract if present rates of algal growth and space utilization are maintained.

Development of ice biota in a temperate sea area (Gulf of Bothnia)

A study of sea ice biota was carried out in the Gulf of Bothnia (northern Baltic Sea) during the winter of 1989–1990. Samples (ice cores) were taken at a coastal station at regular time intervals during the ice season. Chlorophyll a concentration, algal species distribution, bacterial numbers, and primary and bacterial production were measured. Colonization of the ice began in January when daylight was low. As the available light increased, the algae started to grow exponentially. The vertical chlorophyll a distribution changed and algal species composition and biomass changed during the season. During the initial and middle phase of colonization, ice-specific diatoms, Nitzschia frigida and Navicula pelagica, dominated the algal biomass. Nutrients (PO4 3− and NO3j) were found to be depleted during the time of algal exponential growth. The maximum algal biomass exceeded 800 μg C 1−1. The primary production supplied food for heterotrophic organisms. The presence of heterotrophic organisms of different trophic levels (bacteria, flagellates, ciliates and rotifers) indicated an active microbial food web.

Influence of Size on Fate and Ecological Effects of Kepone in Physical Models

Three different sizes of marine microcosms were used to study the influence of two features of spatial scale on the chemical fate and ecological effects of the pesticide Kepone. Increasing the size of microcosms reduced the ratio of wall surface area to volume of contained sea water, but increased the number of benthic species due to increasing sample size. Other features of spatial scale, such as water turbulence, water turnover, etc., were held constant. Intact water-column and benthic communities from a north-temperate marine system were coupled together in 9.1-, 35.0-, and 140.O-L containers. Kepone at 20.4 nmol/L was added to these microcosm systems over a 30-d period. A 3 x 2 factorial design was used to discern the effects of size and Kepone. In the absence of Kepone the phytoplankton community exhibited excessive growth relative to the field system for all system sizes. Growth was directly related to the size of microcosms. In addition, the time required to achieve maximum algal biomass was also directly related to size. Release of a growth-stimulating compound(s) from fouling organisms settling on the microcosm walls and size-dependent increases in benthic species provided the best explanation for the observed phytoplankton dynamics. Addition of Kepone indirectly increased phytoplankton densities by reducing through toxic effects, the grazing pressure of zooplankton. Because this effect and mechanism was dependent upon the size of the system, the sensitivity of future perturbation studies may be enhanced by producing similar or related variations in system size. The concentration of Kepone in surficial sediments was also size dependent. Since the average concentrations of Kepone in all water columns were statistically equivalent, these findings were the result of sediment bioturbation coupled with preferential partitioning of Kepone from liquid to the solid, organic phase of sediments. Ecological risk assessments based upon data derived from these systems are therefore dependent upon size. Furthermore, the smaller the size, the greater the underestimate in sediment exposure and the ecological risks of Kepone.

Occurrence of phosphorus and its potential remohilization in the littoral sediments of a productive English lake

SUMMARY. 1. Vertical profiles of pH were measured at nine shallow water (&lt;5m) locations in Esthwaite Water. These indicate strong gradients of pH near the sediment water interface suggesting a marked buffering capacity of the sediments.2. Thirteen littoral sediment cores were horizontally sectioned and sequentially extracted (0.5 M NaHCO3, 0.1 M NaOH, 1 M HCI) and analysed for soluble reactive phosphorus. The core sections were also analysed for total phosphorus and per cent organic content to determine the vertical and areal variability of phosphorus within the littoral sediments of Esthwaite Water.3. The rate of release of phosphorus from intact sediment cores was measured in the laboratory as a function of the pH of overlying water, yielding the relationship log K=0.54 pH−3.94, K=mg Pm−2day−1. The maximum release rate measured was 75 mg P m−2 day−2 at pH = 10.5.4. Experiments on sediment slurries indicate that the release of phosphorus at pH 10 is rapid with approximately 50% of the total NaHCO3+ NaOH extractable phosphorus being released within 3 h.5. Phosphorus release from the littoral sediments may equal or exceed external sources plus hypolimnetic inputs during periods of high pH associated with times of maximum algal biomass.

Physical control of the horizontal patchiness of sea-ice microalgae

Factors controlling the horizontal distribution of sea-ice microalgae were studied in Southeastern Hudson Bay and adjacent Manitounuk Sound (Canadian Arctic). Both large (-30 km) and small (0.3 to 500m) scales of variability were investigated. Results showed that salinity was the most important factor controlling large scale distribution of the ice-microalgal biomass, through its effect on the structure of the ice (surface available for colonization). Variation in the thickness of the snow-ice cover, which determines irradiance at the bottom of the ice, was the factor controlling distribution of the algal biomass at smaller scale (diameter of patches of microalgal biomass ranging between 20 and 90 m). The relation between ice-algal abundance and snow-ice thickness changed however over the season. At the beginning of the growing season (in April when the bottom-ice irradiance was higher than a minimum critical irradiance), maximum algal biomass was observed under areas covered by the smallest snow depths. Towards the end of the season, when light transmitted through the snow-lce cover increased, maximum algal biomass was observed under areas covered by the deepest snow. This suggests that ice algae have both minimum and maximum critical light levels. The minimum level is the irradiance below which there is no photosynthetic activity (Imi, 7.6 CL Einst m-2 S-') and the maximum level corresponds to the inhibiting light intensity, which may vary during the growth season. The horizontal heterogeneity of the snow-ice cover, whlch is influenced by wind at the air-ice interface, thus provides diversified bottom-ice habitats where irradiance is compatible or not with the physiological limits of the ice microalgals cells. This results in a strong patchiness in distribution of ice-bottom microalgae.

A tubular bioreactor for photosynthetic production of biomass from carbon dioxide: Design and performance

AbstractA theory of photobioreactor design is developed. A photobioreactor was constructed in the form of a loop made from 52 m of glass tubing of 1 cm bore; the loop covered about 0.5 m2. The culture was illuminated with mercury halide lamps to reproduce sunlight. Computer control was used to maintain constant biomass concentration. The influence of radiation on the reactor temperature is quantitatively predicted. An air lift system was preferred to a liquid pump for culture recycle. The energy required for culture recycle in the loop with Reynolds number 2000 was 0.6 W m−2. The CO2 gas/liquid transfer rate achieved was sufficient to meet the maximum possible demand with solar irradiation. The O2 gas/liquid transfer rate was sufficient to meet the maximum respiration demand at night. The maximum algal biomass concentration achieved exceeded 20 g dry weight litre−1. A biomass concentration of 8 g dry weight litre−1 was found to be convenient for normal operation. The maximum uptake of light in the available wavelength range (400–700 nm) was 38 W m−2, this corresponds to utilisation of solar irradiation up to 89 W m−2. Below the maximum light uptake rate the efficiency of storage of light energy in the biomass corresponded to 16.6% of solar energy.

Responses to Crude Oil Contamination by Cricotopus (Cricotopus) bicinctus and C. (C.) mackenziensis (Diptera: Chironomidae) in the Fort Simpson Area, Northwest Territories

Cricotopus (Cricotopus) bicinctus (Meigen) and C. (C.) mackenziensis Oliver, two common species of Chironomidae in the Fort Simpson area, N.W.T., were examined for changes resulting from experimental field exposure to Norman Wells crude oil. Larvae of both species were always present in higher numbers on oiled than unoiled artificial substrates but numbers of C. bicinctus increased more quickly than C. mackenziensis in response to the oil. Cricotopus mackenziensis larvae occurred in higher numbers than C. bicinctus larvae on unoiled artificial substrates. Cricotopus bicinctus tended to dominate C. mackenziensis on oiled artificial substrates. Size of larvae, as measured by head capsule width, was unaffected by increased food supply during periods of maximum algal biomass on oiled artificial substrates. Larvae on oiled artificial substrates apparently produced part of another generation when compared to larvae on unoiled artificial substrates.

The Effects of pH on Lake Water Chemistry and Phytoplankton in a LaCloche Mountain Lake

Abstract Some LaCloche Mountain Lakes and other soft water Shield lakes in the vicinity of Killarney Provincial Park (some 50–310 km south west of Sudbury, Ontario) have for the last decade been the subject of research on lake acidification. Acid precipitation (mainly from sulphur oxides) and lake waters of low buffering capacity apparently compound the problem. Typical pH values for such lakes range from 6.0–6.5, but pH values over the range 3.8–5.0 are not now uncommon. Loss of fish populations especially as a result of reproductive failure and changes in Zooplankton species composition have accompanied the lowering of pH which has occurred rapidly over the last two decades. The present study was on Carlyle Lake (Killarney Provincial Park) during the spring, summer, fall and winter of 1974–75. The pH values of water in cylinders floating in the lake were maintained at 4.0, 5.0, 6.0 and 6.5 respectively, for periods of six weeks, by additions of sulphuric acid or sodium hydroxide. Phytoplankton biomass was estimated by utermöhl technique, species identified and quantified at regular intervals during experiments. Maximum algal biomass in the cylinders occurred at pH 5.0 (close to the present pH of the lake). All major taxa had biomass maxima close to pH 5.0, with the exception of Cryptomonas ovata Ehrenberg, Chroomonas caudata Geit and Peridinium limbatum (Stokes) Lemm. which had maxima at pH 4.0. A preliminary comparison between the species composition and diversity of phytoplankton populations in LaCloche Lakes and in recently acidified lakes in similar geological rock basins in Western Europe is made.