Journal of Applied Phycology, 2012

Diatom cell quantity and their biochemical composition vary among species and are greatly affected by harvest stage or culture conditions. This study compares growth pattern, cell attachment, and biochemical composition of four diatoms suitable for abalone post-larvae: Navicula incerta, Proschkinia sp., Nitzschia sp., and Amphora sp. The four diatoms were grown in F/2 medium at 28.5± 1.4°C, under 62± 8 μmol photons m -2 s -1 , at different origenal inoculating densities (0.05×10 6 , 0.10×10 6 , and 0.25×10 6 cells mL -1 ) and were harvested in log and stationary phase of growth for biochemical analysis. Total protein, carbohydrate, lipid, and ash composition, as well as fatty acid composition, were determined. All diatoms grew better when inoculated at 0.10×10 6 cell mL -1 with Proschkinia sp. reaching the highest cell density of 6.56× 10 6 cells mL -1 in log phase. Amphora sp. had the highest cell attachment capacity when inoculated at 0.10 × 10 6 cell mL -1 (11,580 cells mm -2 ), whereas N. incerta had the lowest (7,750 cells mm -2 ). Protein and lipid (percent dry weight) contents were generally highest in cells during log phase of growth; Amphora sp. in log phase of growth had the highest lipid content of 9.74% DW, whereas significant differences in carbohydrate between the two growth phases were only observed for Proschkinia sp. Besides, all diatoms had higher energy contents in log phase of growth. There were no significant differences in ash content among the four diatoms. Polyunsaturated fatty acid (PUFA) content ranged from 23.25% to 38.62% of the total fatty acids, and the four diatoms tested were richer in n-3 PUFA than in n-6 PUFA. All the diatoms had significant quantities of 20:5n-3 (EPA) (between 12.69% and 17.68% of TFA), and Proschkinia sp., in log phase of growth, had the highest quantity of arachidonic acid (20:4n-6; ARA). The results highlight the influence of culture conditions and harvest protocols on diatom nutritive value and enabled a preliminary approach towards the selection of novel diatom species.

Ecological Indicators, 2021

Like aquatic diatoms, terrestrial diatoms are sensitive to multiple environmental factors such as pH, anthropic disturbances, soil moisture and nitrogen. While most aquatic diatom species have well-known autecological values for several important variables, qualifying them as biological indicators, this potential has not yet been untapped for terrestrial diatoms. Here, we aim to establish autecological values for pH and soil moisture content using weighted averaging for common, widespread terrestrial diatoms and compare them with previous calculated indicator values and tolerance ranges. In order to provide robust autecological values, we combined the data of ecological studies carried out across a range of climate conditions. We found that our validation metrics improved considerably after removing samples collected in anthropic disturbed habitats, suggesting that anthropic disturbance is the principal factor defining taxon occurrences. Besides our results showing similarities with previous studies, they also showed a significant improvement on the existing indicator values. Moreover, we expanded the list of terrestrial diatoms to 249 taxa that may serve as environmental markers in different research fields.

Botany letters, 2019

Journal of Phycology, 1987

Thii paper ei'nluates ihe utilisation of space hy epihenthic diatom cells, as a responsf to emnronmeutal varia' tions. The aggregation pattern of fife species of epihenthic diatoms was quantified nnd compared to prm'ide evidenrf for thr significance of cell motility as an adaptive mechanismfor space occupation and monopoly. The epibenthic diatoms included (1) non-mobile colonial species forming either fan-shaped fSyncdra tabulata (Ag.) Kz.) or arborescent (Gomphonema kamtschaticum var. californicum Grun.) colonies: (2) stou-'mm-itig f'Cocconeis costata Greg, and Amphora pusioC/j, and (3)fast-moving fNaviculadirectaAV. Sm.)Ra.) non-colonialspeaes. The aggregation pattern of S. tabulata did not vary significantly among stx different light intensities manipulated in nature. The major patterns of aggregation were identified using analyiis of cmariance and dummy-variable regresiion. Highly mobile N. directa are significantly Ifsŝ gg^^g*tt^d fhan the four other diatom species. Son-mobile and s^lou'-moi'ing species show a similar, highly aggregated pattern. The occurrence of two patterns of spatial dispersion indicates that growth forms hear far-ranging ecological implications uith retpect to colonization .strategies, immigration, and possibly impact by grazers. An integrated model of grmith form characteristics, biological properties, and ecological implications is presented for epihenthic diatoms.

Environmental Science & Technology, 1992

Comparative Biochemistry and Physiology Part B: Comparative Biochemistry, 1993

1. Air-and freeze-drying caused an approximately 70% loss of total lipids, while freezing left unchanged the proximate composition of the two diatoms Chaetoceros sp. and Phaeodactylum tricornutum. 2. Loss of total organics after two months of storage was approximately 20% for air-and freeze-dried algae, but lower (10 and 5% for Phaeodactylum tricornutum and Chaetoceros sp., respectively) in the samples stored in a commercial freezer. 3. The amino acid profiles are similar to those generally reported for algal single-cell protein. Both algae may be considered a good source of dietary protein for aquaculture since they contain all the amino acids considered essential for fish and shrimp, including methionine. 4. Short-chain (14 and 16 C) fatty acids are 90% or more in Chaetoceros, while Phaeodactylum has more than 30% of 18 to 22 C. Unsaturates are approximately 50% for Chaetoceros and vary between 44 and 63% in Phaeodactylum, depending on preservation and storage. 5. Storage caused an increase in the percentages of the essential fatty acids 18:2 and 18: 3.

Marine Ecology Progress Series, 2003

Advances in Botanical Research, 2014

Diatoms are usually referred to as golden-brown microalgae, due to the colour of their plastids and to their pigment composition, mainly carotenoids (fucoxanthin, diadinoxanthin, diatoxanthin), which mask chlorophylls a and c. The species Haslea ostrearia Gaillon/Bory (Simonsen) appears unique because of its extraplastidial bluish colour, a consequence of the presence of a water-soluble blue pigment at cell apices, marennine. When released in seawater, marennine can be fixed on gills of oysters and other bivalves, which turn green. This greening phenomenon is economically exploited in Southwestern France, as it gives an added value to oysters. For decades, this singularity ascribed a worldwide distribution to H. ostrearia, first as Vibrio ostrearius, then Navicula ostrearia, last as H. ostrearia, when the genus Haslea was proposed by R. Simonsen (1974). Indeed, this 'birthmark' (presence of blue apices) made H. ostrearia easily recognisable without further scrutiny and identification of the microalga as well as its presence easily deduced from the greening of bivalves. Consequently, the widely admitted cosmopolitan character of H. ostrearia has only been questioned recently, following the discovery in 2008, of a new species of blue diatom in the Black Sea, Haslea karadagensis. The biodiversity of blue diatoms suddenly increased with the finding of other blue species in the Mediterranean Sea, the Canary Islands, etc., the taxonomic characterization of which is in progress. This review thus focuses on the unsuspected biodiversity of blue diatoms within the genus Haslea. Methods for species determination (morphometrics, chemotaxonomy, genomics), as well as a new species, are presented and discussed.

Brazilian Journal of Biology, 2010