Book

Intercalibration and Distribution of Diatom Species in the Baltic Sea. Vol. 3

January 1995

Publisher: Opulus Press Uppsala
ISBN: 9197162280

Authors:

Pauline J. M. Snoeijs

Stockholm University

Marina Potapova

Drexel University

Volume 3 in a series which has resulted from a joint intercalibration programme of the Baltic Marine Biologists (BMB) Working Group 27. Each species is illustrated with a photograph and extensive references to the appropriate up-to-date information literature. This book can be ordered from http://www.nhbs.com and other internet book stores. In volumes 1-5 the following 500 species are treated, all, illustrated, each on a separate page: Achnanthes amoena Achnanthes bahusiensis Achnanthes bremeyeri Achnanthes brevipes Achnanthes brevipes var. intermedia Achnanthes cf. minuscula Achnanthes dispar Achnanthes fimbriata Achnanthes fogedii Achnanthes groenlandica Achnanthes lemmermannii Achnanthes linkei Achnanthes longipes Achnanthes oblongella Achnanthes pericava Achnanthes submarina Achnanthes vistulana Achnanthidium microcephalum Achnanthidium minutissimum Achnanthidium thermale Actinocyclus normanii Actinocyclus normanii fo. subsalsus Actinocyclus octonarius var. crassus Actinocyclus octonarius var. tenellus Actinoptychus senarius Amphora abludens Amphora acutiuscula Amphora beaufortiana Amphora cf. bacillaris Amphora cf. exigua Amphora cf. tenerrima Amphora coffeaeformis Amphora commutata Amphora copulata Amphora decussata Amphora fogediana Amphora helenensis Amphora holsatica Amphora hyalina Amphora hybrida Amphora laevissima Amphora lineolata Amphora luciae Amphora macilenta var. typica Amphora maletractata var. constricta Amphora micrometra Amphora ostrearia var. lineata Amphora ovalis Amphora pediculus Amphora rhombica var. intermedia Amphora robusta Amphora staurophora Amphora subholsatica Amphora veneta Amphora wisei Anaulus balticus Aneumastus minor Aneumastus tusculus Anomoeoneis sphaerophora fo. costata Anomoeoneis sphaerophora fo. sculpta Anorthoneis vortex Ardissonea crystallina Ardissonea fulgens Asterionella formosa Attheya decora Attheya septentrionalis Aulacoseira islandica Aulacoseira subarctica Bacillaria paxillifer Berkeleya fennica Berkeleya micans Berkeleya rutilans Biremis ambigua Biremis lucens Brachysira aponina Kützing Brachysira vitrea Brebissonia lanceolata Caloneis aemula Caloneis amphisbaena Caloneis amphisbaena fo. subsalina Caloneis bacillum Caloneis crassa Campylodiscus bicostatus Campylodiscus clypeus Campylodiscus echeneis Catenula adhaerens Cavinula cocconeiformis Cavinula pseudoscutiformis Cerataulina pelagica Cerataulus turgidus Chaetoceros affinis Chaetoceros brevis Chaetoceros cf. borealis Chaetoceros cf. fallax Chaetoceros danicus Chaetoceros decipiens Chaetoceros diadema Chaetoceros holsaticus Chaetoceros mitra Chaetoceros muelleri var. subsalsum Chaetoceros similis Chaetoceros simplex Chaetoceros subtilis Chaetoceros throndsenii Chaetoceros wighamii Cocconeis costata Cocconeis disculus Cocconeis molesta var. crucifera Cocconeis neothumensis Cocconeis pediculus Cocconeis peltoides Cocconeis placentula Cocconeis placentula var. euglypta Cocconeis pseudomarginata Cocconeis quarnerensis Cocconeis scutellum Cocconeis speciosa Cocconeis stauroneiformis Coscinodiscus asteromphalus Coscinodiscus granii Coscinodiscus radiatus Coscinodiscus wailesii Cosmioneis pusilla Craticula cuspidata Ctenophora pulchella Cyclostephanos dubius Cyclotella atomus Cyclotella choctawhatcheeana Cyclotella meneghiniana Cyclotella radiosa Cyclotella schumannii Cyclotella stelligera Cylindrotheca closterium Cymatopleura elliptica Cymatopleura solea Cymbella affinis Cymbella cistula Cymbella helvetica Cymbella lanceolata Cymbella pusilla Denticula creticola Denticula sundayensis Denticula tenuis var. crassula Diatoma bottnica Diatoma moniliformis Diatoma tenuis Diatoma vulgaris Dickieia subinflata Didymosphenia geminata Dimeregramma minor Diploneis decipiens var. parallela Diploneis didyma Diploneis domblittensis Diploneis interrupta Diploneis litoralis Diploneis mauleri Diploneis oculata Diploneis smithii Diploneis smithii var. dilatata Diploneis smithii var. pumila Diploneis smithii var. rhombica Diploneis stroemii Diploneis suborbicularis Ditylum brightwellii Donkinia angusta Donkinia recta var. minuta Ellerbeckia arenaria Encyonema caespitosum Encyonema lacustre Encyonema prostratum Encyonema silesiacum Encyonopsis behrei Encyonopsis microcephala Entomoneis paludosa Entomoneis pseudoduplex Entomoneis punctulata Epithemia adnata Epithemia sorex Epithemia turgida Epithemia turgida var. westermannii Eucampia zodiacus Fallacia clepsidroides Fallacia cryptolyra Fallacia florinae Fallacia forcipata Fallacia litoricola Fallacia plathii Fallacia pseudolitoricola Fallacia pseudony Fallacia pygmaea Fallacia tenera Fragilaria amicorum Fragilaria capucina Fragilaria crotonensis Fragilaria gedanensis Fragilaria heidenii Fragilaria hyalina var. durietzii Fragilaria inflata var. istvanffyi Fragilaria parasitica Fragilaria striatula Fragilaria vaucheriae Fragilariopsis cylindrus Frustulia creuzburgensis Gomphocymbella ancyli Gomphonema acuminatum var. coronatum Gomphonema olivaceum Gomphonema parvulum Gomphonemopsis exigua Gomphonemopsis exigua var. platypus Gomphonemopsis pseudexigua Grammatophora marina Grammatophora oceanica Guinardia flaccida Gyrosigma acuminatum Gyrosigma attenuatum Gyrosigma balticum Gyrosigma eximium Gyrosigma fasciola Gyrosigma macrum Gyrosigma strigilis Hantzschia virgata Hantzschia virgata var. gracilis Hantzschia virgata var. wittii Haslea crucigera Haslea crucigeroides Haslea ostrearia Hustedtiella baltica Hyalodiscus scoticus Hyalosira delicatula Karayevia clevei Leptocylindrus danicus Leptocylindrus minimus Licmophora abbreviata Licmophora communis Licmophora dalmatica Licmophora debilis Licmophora gracilis var. anglica Licmophora hyalina Licmophora oedipus Licmophora rhombica Lunella bisecta Luticola mutica Lyrella sulcifera Martyana atomus Martyana martyi Martyana schulzii Mastogloia baltica Mastogloia braunii Mastogloia elliptica Mastogloia exigua Mastogloia lanceolata Mastogloia pumila Mastogloia pusilla Mastogloia smithii Mastogloia smithii var. amphicephala Melosira arctica Melosira lineata Melosira moniliformis Melosira nummuloides Melosira varians Melosira westii fo. parva Meridion circulare Navicula aboensis Navicula arenaria Navicula armoricana Navicula bipustulata Navicula bottnica Navicula capitata var. hungarica Navicula clamans Navicula crucicula Navicula cruciculoides Navicula cryptocephala Navicula decussis Navicula digitoradiata Navicula directa Navicula duerrenbergiana Navicula eidrigiana Navicula finmarchica Navicula flanatica Navicula germainii Navicula germanopolonica Navicula gregaria Navicula infirmitata Navicula integra Navicula jentzschii Navicula lanceolata Navicula laterostrata Navicula lesmonensis Navicula margaritiana Navicula meniscus Navicula microdigitoradiata Navicula oblonga Navicula oestrupii Navicula palpebralis Navicula pavillardii Navicula pelagica Navicula peregrina Navicula perminuta Navicula phyllepta Navicula platystoma Navicula portanova Navicula protracta Navicula pseudocrassirostris Navicula radiosa Navicula ramosissima Navicula ramosissima var. torquata Navicula reinhardtii Navicula rhynchocephala Navicula salinarum Navicula scutelloides Navicula slesvicensis Navicula starmachioides Navicula supralitoralis Navicula tripunctata Navicula vanhoeffenii Navicula viminoides Neidium iridis var. amphigomphus Neosynedra provincialis Nitzschia acicularis Nitzschia ardua Nitzschia aurariae Nitzschia bacillum Nitzschia brevissima Nitzschia cf. angustatula Nitzschia cf. distans Nitzschia clausii Nitzschia dippelii Nitzschia dissipata Nitzschia dubia Nitzschia dubiiformis Nitzschia elegantula Nitzschia filiformis Nitzschia frigida Nitzschia frustulum Nitzschia grossestriata Nitzschia heufleriana Nitzschia inconspicua Nitzschia littorea Nitzschia lorenziana Nitzschia microcephala Nitzschia paleacea Nitzschia pusilla Nitzschia recta Nitzschia recta var. robusta Nitzschia reversa Nitzschia salinicola Nitzschia scalaris Nitzschia scalpelliformis Nitzschia sigma Nitzschia sigmoidea Nitzschia thermaloides Nitzschia valdestriata Nitzschia vitrea Odontella aurita Odontella mobiliensis Odontella sinensis Opephora marina Opephora olsenii Paralia sulcata Parlibellus berkeleyi Parlibellus delognei Parlibellus hamulifer Parlibellus plicatus Pauliella taeniata Petrodictyon gemma Petroneis granulata Petroneis humerosa Petroneis latissima Petroneis marina Petroneis monilifera Pinnularia acuminata Pinnularia appendiculata Pinnularia cruciformis Pinnularia elegans Pinnularia halophila Pinnularia lundii Pinnularia mesolepta Pinnularia neomajor Pinnularia quadratarea Placoneis clementis Placoneis gastrum Placoneis placentula Plagiogramma staurophorum Plagiotropis lepidoptera Plagiotropis tayrecta Plagiotropis vanheurckii Plagiotropis vitrea Planothidium calcar Planothidium delicatulum Planothidium dubium Planothidium frequentissimum Planothidium oestrupii Planothidium rostratum Planothidium septentrionalis Pleurosigma aestuarii Pleurosigma angulatum Pleurosigma elongatum Pleurosigma formosum Pleurosigma lanceolatum var. cuspidatum Pleurosigma salinarum Pleurosigma subsalsum Pleurosira laevis fo. polymorpha Porosira glacialis Proboscia alata Proschkinia poretzkajae Psammodictyon panduriforme var. continua Psammothidium bioretii Psammothidium punctulatum Psammothidium rossii Pseudogomphonema kamtschaticum Pseudonitzschia pseudodelicatissima Pseudonitzschia pungens Pseudosolenia calcar-avis Pseudostaurosira brevistriata Pseudostaurosira brevistriata var. inflata Pseudostaurosira perminuta Pseudostaurosira zeillerii Pteroncola inane Reimeria sinuata Rhabdonema arcuatum Rhabdonema minutum Rhizosolenia delicatula Rhizosolenia fragilissima Rhizosolenia hebetata fo. semispina Rhizosolenia pungens Rhizosolenia setigera Rhoicosigma compactum Rhoicosphenia curvata Rhopalodia acuminata Rhopalodia brebissonii Rhopalodia gibba Scoliotropis latestriata Sellaphora bacillum Sellaphora pupula Skeletonema costatum Skeletonema subsalsum Stauroneis acuta Stauroneis phoenicenteron Stauroneis simulans Stauroneis spicula Staurophora amphioxys Staurophora salina Staurophora wislouchii Staurosira cf. construens var. venter Staurosira construens Staurosira construens var. binodis Staurosira elliptica Stephanodiscus binderanus Stephanodiscus hantzschii Stephanodiscus hantzschii fo. tenuis Stephanodiscus minutulus Stephanodiscus neoastraea Stephanodiscus parvus Stephanodiscus rotula Striatella unipunctata Surirella brebissonii Surirella brightwellii var. baltica Surirella crumena Surirella minuta Surirella striatula Synedra acus Synedra ulna Tabellaria fenestrata Tabellaria flocculosa Tabularia fasciculata Tabularia investiens Tabularia ktenoeides Tabularia tabulata Tabularia waernii Terpsinoë americana Thalassionema nitzschioides Thalassiophysa hyalina Thalassiosira anguste-lineata Thalassiosira baltica Thalassiosira eccentrica Thalassiosira guillardii Thalassiosira hyperborea var. lacunosa Thalassiosira hyperborea var. pelagica Thalassiosira lacustris Thalassiosira levanderi Thalassiosira oestrupii Thalassiosira proschkinae Thalassiosira pseudonana Thalassiosira punctigera Thalassiosira weissflogii Trachyneis aspera Tryblionella apiculata Tryblionella circumsuta Tryblionella coarctata Tryblionella gracilis Tryblionella hungarica Tryblionella levidensis Tryblionella littoralis Tryblionella littoralis Tryblionella navicularis Tryblionella plana Tryblionella plana var. fennica Tryblionella punctata Tryblionella salinarum Undatella quadrata

Amphora micrometra Giffen and Halamphora valdeminutissima sp. nov., two tiny benthic diatom species observed in the Black Sea

Article

Nov 2023

During a survey of the diatom flora present on an artificial substratum (plexiglass) submerged off the southern Bulgarian Black Sea coast, a small-celled diatom taxon, reported previously from the Black Sea as Amphora (Halamphora) sp. S21, was observed. Detailed light and scanning electron microscope observations showed that the original taxon actually included two different taxa: an unknown Halamphora species described here as H. valdeminutissima sp. nov., and a second taxon, which, based on SEM observations, could be identified as Amphora micrometra Giffen. The morphology of both taxa is described in detail and a comparison with similar taxa is provided. Additionally, environmental data of the habitat is also provided.

Biodiversity of the benthic diatom flora in the coastal zone of the Gulf of Gdańsk: a case study of the Gdynia–Sopot transect

Article

Full-text available

Jun 2022

The objective of this study is to determine microhabitat preferences of benthic species occurring in epilithic (living on stones), epipsammic (growing on sand), epipelic (growing on mud) and epiphytic (living on seagrass) assemblages of the shallows of the Gulf of Gdańsk (southern Baltic Sea). The study material was collected from 19 sites along the Gdynia–Sopot coastal zone, including the Port of Gdynia. Most of the identified diatom taxa were observed in two or three microhabitats. However, diatom species living in only one type of microhabitat and those occurring in all analyzed microhabitats were also recorded. Autecological preferences of the identified diatoms indicate organic pollution of the coastal zone of Gdynia and Sopot. However, a higher frequency of α-mesosaprobionts and polysaprobionts indicates an increase in organic pollution in the Port of Gdynia and Marina Sopot, which is associated with intense port activity and large tourist traffic.

Biodiversity of the benthic diatom flora in the coastal zone of the Gulf of Gdańsk: a case study of the Gdynia–Sopot transect

Article

Full-text available

Sep 2022
OCEANOL HYDROBIOL ST

Biodiversity of benthic diatom flora in the coastal zone of Puck Bay (southern Baltic Sea): a case study of the Hel Peninsula

Article

Sep 2020

The paper presents the results of the analysis of diatoms from surface sediments (stones, sands) and macroflora (seagrass, macroalgae) collected at 16 sampling sites located along the inner coastal zone of Puck Bay (southern Baltic Sea) along the Hel Peninsula. The main diatom species of epilithon, epipsammon and epiphyton were characterized with respect to their autecological preferences (habitat, salinity, trophic status, saprobity). Three groups of diatoms were distinguished with respect to the type of substrate based on the results of benthic flora analysis: diatoms (i) of one type of substrate, (ii) of two types and (iii) those occurring on all types of substrates. Moreover, the distribution of benthic diatom communities indicates ecological differences in the study area. Marine and brackish-water species were observed in large numbers in the coastal zone of the Outer Puck Bay, whereas freshwater flora occurred with a higher frequency in the coastal zone of the Puck Lagoon. The content of polysaprobionts and of α-mesosaprobionts indicates that the region of the Hel Tip is highly eutrophicated and very polluted. The coast in the vicinity of Kuznica is less polluted, whereas the best environmental conditions are found in the Jurata–Jastarnia region, as evidenced by the frequency of diatoms that are β-mesosaprobionts.

Insights into Diatom Substrate Preferences in the Inter-Tidal Zone of a Subarctic Coast

Article

Full-text available

Oct 2023

Diatoms are reliable environmental bioindicators, but their application in coastal environments remains limited. Substrate has been put forward in the literature as an important variable in determining diatom habitat preferences. This study focuses on benthic diatom assemblages and their relationship with substrate specificity in a subarctic tidal environment, which could be relevant for environmental monitoring and management. A variety of substrates were sampled and physicochemical variables measured in various areas of the Bay of Sept-Îles region (northern Gulf of Saint-Lawrence, Canada). We recorded 606 species at 14 sites from 11 substrate types to determine the associations between diatoms and their habitats. Our results suggest that the variability of assemblages in the bay is the result of a combination of the identified variables (temperature, salinity, and total dissolved solids), explaining 26.5% of the variation, and other unmeasured variables (e.g., nutrients, wave action, and currents). Substrate was not identified as a significant variable in the statistical analyses. However, some common species in the surveyed assemblages appeared to show preferences for the substrates they colonized.

Corrigendum to: Watching the tide roll away – contested interpretations of the nature of the Lower Lakes of the Murray Darling Basin

Article

Jan 2020

Peter Gell

The Murray Darling Basin Plan (Murray Darling Basin Authority 2012) represents the largest investment by government in an Australian environmental management challenge and remains highly conflicted owing to the contested allocation of diminishing water resources. Central to the decision to reallocate consumptive water to environmental purposes in this Plan was the case made to maintain the freshwater character of two lakes at the terminus of the Murray Darling Basin, in South Australia. This freshwater state was identified as the natural condition on the basis of selected anecdotal evidence and was enshrined in the site's listing under the Ramsar Convention. The commitment to the freshwater state was challenged under drought when sea water was seen as a means of averting acidification when low river flows risked the exposure of sulfidic sediments. Independent evidence from water quality indicators (diatoms) preserved in lake sediment records, however, attested to an estuarine, albeit variable, condition before the commissioning of near-mouth barrages in 1940. This interpretation for a naturally estuarine history, published after peer review, was overlooked in a report to the South Australian government, which argued, without the provision of new evidence from the lakes, that they were fresh for their entire history. This revised interpretation is widely cited in the scientific literature, government reports and online discussion and underpins a watering strategy aimed at a freshwater future for the Lower Lakes. The allocation of large volumes of fresh water to achieve this condition presents significant difficulties owing to the highly contested nature of water use across the Basin.

Diatom atlas of the intertidal mudflats of the Loire estuary

Technical Report

Full-text available

Dec 2019

In order to establish the ecological status of water bodies, the European Water Framework Directive (WFD) is based on the evaluation of a number of biological quality elements, as well as physical parameters supporting the biology. In estuaries, phytoplankton monitoring was not considered relevant because of the high turbidity characterizing the large metropolitan estuaries and the French overseas departments (Guyana). This work is part of a study titled “Évaluation de l’état écologique des masses d’eau de transition dans le cadre de la DCE - Étude de la pertinence du suivi des peuplements du microphytobenthos estuarien” and funded by the Agence Française pour la Biodiversité (AFB), that is currently ongoing, and is considering the possibility of using the microphytobenthos (MPB) as a biological indicator of the ecological status of estuaries and other transitional waters. Microphytobenthos assemblages are usually dominated by diatoms in temperate estuarine intertidal areas. In this iconographic atlas, the diatoms found in 29 samples from 3 intertidal mudflats of the Loire estuary and collected during two field campaigns (Spring and Autumn 2016) are illustrated and identified. The atlas has 602 LM photographs of 359 different taxa and stands as one of the most complete and detailed illustrated descriptions of these communities in French estuaries. Of the 359 taxa, 285 were identified to the species level, whilst 74 were identified to the genus level. The main aims of the atlas are to become a reference work for the Loire estuary, but also to become a useful identification guide for other French estuaries, given the lack of easily accessible and illustrated taxonomic works on intertidal diatoms. For each taxon additional information is given, namely: 1) spatiotemporal distribution; 2) OMNIDIA four-letter code and s and v values for the IPS index (Indice de Polluosensibilité Spécifique); 3) morphometric data gathered from measurements made on 1142 valves and frustules; 4) autecological information (i.e. salinity preferences, habitat and growth-form). A succinct site description is provided, as well as, detailed protocols on microphytobenthos extraction and slide preparation that were specifically adapted for these sediment-dwelling diatom assemblages.

Salinity, nutrients and physical disturbances affect the communities of the most abundant benthic diatom genera in the coastal Baltic Sea and rock pools

Article

Feb 2025
NOVA HEDWIGIA

Environmental and stochastic processes drive diatom taxonomic and functional temporal beta diversity

Article

Aug 2024
MAR ECOL-PROG SER

ABSTRACT: Studying patterns of biodiversity is central to ecological research. Temporal beta diversity, i.e. the change in community composition over time, has emerged as a promising study field during the last decades. Following global climatic change, understanding the consequences of environmental alterations on temporal community composition has become increasingly important. We examined patterns and drivers of temporal beta diversity and whether the temporal variation in community composition is related to temporal environmental variation among 9 coastal diatom communities sampled 12 times at a ca. 10 d interval. We applied a temporal beta diversity index (TBI) decomposed into gains and losses to quantify changes in taxonomic and functional community similarity through time, and for environmental variables to determine temporal change in local abiotic conditions. We assessed environmental and spatial drivers of temporal community change by regression models and partitioned variation in the community composition according to sampling day by distance-based redundancy analyses. Taxonomic TBI was higher than functional TBI, characterized by sharper changes in species gains and losses. Taxonomic TBI was explained by site location, whereas functional TBI had a linkage with both spatial and environmental variables. Environmental TBI was significantly related to taxonomic TBI only. The sites significantly differing in taxonomic or functional TBI did not coincide with those with a significantly different environmental TBI between the sites. The communities were probably structured by both environmental variation and random stochastic processes, creating unpredictability in the TBI. Our results highlight the importance of rapid environmental alterations in shaping temporal beta diversity within dynamic coastal communities.

Holocene environmental changes inferred from palaeobotanical data of Curonian Lagoon sediments

Article

Full-text available

Jan 2024
BALTICA

Environmental development and water level changes in the south-western part of the Curonian Lagoon are reconstructed based on the results of bottom sediment investigations, including data on lithology, diatoms, pollen, and radiocarbon dating. Three stages have been identified in the ~ 10000-year history of the lagoon’s development. The diatoms suggest that in the Early Holocene, the southern part of the Curonian Lagoon was a shallow freshwater basin, mainly fed by run-off from the continent. During the Middle Holocene, the study area was a marshy coastal zone. Due to a change in hydrological conditions at the beginning of the Late Holocene, it became an open-water part of the lagoon.

Declining salinity and increasing temperature reduce the diversity and resilience of benthic diatoms

Article

Jan 2024

Climate change will modify the marine ecosystem in several ways, but the effects of changing climate on benthic diatoms, which are one of the most important photosynthesizing organism groups in benthic habitats, are poorly studied. We conducted a mesocosm experiment to investigate the effects of increasing temperature and decreasing salinity on the taxonomic and functional diversity of benthic diatoms. We showed that decreasing salinity affects the taxonomic and functional composition of communities, and the threshold salinity for community composition is ~5. This indicates that when climate change leads to decreasing salinity in brackish systems, the most pronounced changes in communities occur in areas where salinity decreases from >5 to <5. We also showed that both increasing temperature and decreasing salinity exert stress on communities and, hence, lead to the decrease of the alpha and beta diversity of communities. This indicates that climate change reduces the size of the species pool of diatoms. Our results show that, along with the changing climate, we can expect benthic diatom communities to become less diverse and less resilient.

A new species of Craspedostauros (Bacillariophyceae) from the west coast of Sweden, with taxonomic and ecological notes on Craspedostauros laevissimus

Article

Full-text available

Jan 2024
BOT MAR

Since its separation from Stauroneis in 1999, several new species of Craspedostauros were discovered in a variety of habitats and geographic locations, adding morphological and phylogenetic data to the investigations of the genus. In a survey of littoral diatoms of Sweden, both on the west and east coasts, two epiphytic stauros-bearing species were encountered and assigned to Craspedostauros following the characteristic features of this genus, including the possession of a stauros narrower than the central area and cribrate areolae. One species is described as new to science; Craspedostauros lateralis sp. nov., and the other is of uncertain identity but bears morphological similarity to C. laevissimus. Caspedostauros lateralis is a marine epiphytic species found in the west coast of Sweden, off Gothenburg city. Based on light and electron microscopy, a detailed description of the morphological and ultrastructural features of these species is given and a comparison of the distinguishing characters with allied species is discussed. Some ecological data and the occurrence of associated species on the host macrophyte are provided.

Are Toxic Substances Always Toxic? Case Studies of Different Organismal Responses Based on Brackish-Water Microphytobenthic Communities from the Baltic Sea

Article

Full-text available

Nov 2023

In this manuscript, we present the results of ecotoxicological tests conducted on the Baltic microphytobenthos community consisting largely of cosmopolitan species showing the responses at the community (taxonomic composition and structure), population (abundance), and cellular (chloroplast shape) levels. The tests were carried out for three chemicals with different modes of action on photosynthetic organisms, i.e., copper (II) chloride (at concentrations of 2·10⁻⁵ g·dm³ and 2·10⁻³ g·dm⁻³), glyphosate in the form of Roundup® (concentrations ranging from 4.2·10⁻² to 8.5 g·dm⁻³), and the ionic liquid [BMIM]Cl (at concentrations of 1.13·10⁻³ g·dm⁻³ and 1.75·10⁻² g·dm⁻³). The results of the study indicate that the responses of microphytobenthos at each level analysed are highly variable and difficult to predict a priori based on experiments performed on single strains. In addition, it was shown that microphytobenthic communities are relatively resistant to the substances tested, which is due to taxonomic richness and the resulting potential for substitution of sensitive taxa by more resistant taxa. The results obtained in the tests also indicate that the number of cells of individual taxa can remain at a similar level or increase over short periods of time despite the deformation of chloroplasts in a numerous group of cells.

The Relationship between Total Mercury, Its Fractions and Species Diversity of Diatom Taphocoenoses Deposited in Surface Sediments (Southern Baltic Sea)

Article

Full-text available

Nov 2023

Mercury is a toxic metal that in excessive amounts negatively affects the human nervous system. It can biomagnify to enrich successive levels of the trophic web with higher and higher concentrations of Hg. Diatoms are cosmopolitan microalgae that represent the base of the trophic web. The objective of this study was to determine the importance of diatoms in the accumulation of Hg in surface sediments in the example of Puck Lagoon (southern Baltic Sea). The study verified the relationship of mercury forms with diatoms’ characteristic salinity groups and individual diatom species. The identified diatom flora permitted the distinguishment of three regions with different salinity preferences. The obtained results suggest that, together with organic matter and fine sediment fraction, diatoms are an important element of the marine environment in accumulating Hg. Area I, dominated by euhalobous and mesohalobous diatom species, was characterized by a high statistically significant correlation of mesohalobous with HgSO4, Hg in complexes with organic matter and HgS. In Area II, associated with the highest Hg concentrations (ca. 100 ng g−1), euhalobous showed a statistically significant linear correlation with HgSO4. In contrast, in Area III, the freshwater diatom community was associated with stable Hg forms. The identified species showed a connection with labile forms of Hg that can undergo biomagnification.

Diversity of benthic diatoms in the Baltic Sea: alpha and beta diversity, environmental drivers, and diversity–biomass relationships

Article

Jun 2023

Leena Virta

Benthic diatoms are crucial for the functioning of ecosystems, but their diversity patterns along large gradients are poorly studied. By using 3 self-collected data sets along large environmental gradients in the Baltic Sea, represented over spatial scales of 60, 1300, and 2300 km, I investigated whether different aspects of diversity follow general patterns or are context- and region-specific. General diversity patterns along different gradients would likely indicate high resilience of benthic diatoms against differences and changes in the environment, whereas context-dependent patterns would possibly suggest that environmental change is likely to modify diatom communities and that region-specific differences should be considered when designing ecosystem management. I investigated the effect of environmental conditions on taxonomic and functional diatom diversity with distance-based redundancy analyses, variability of taxonomic diversity with species accumulation curves, taxonomic and functional aspects of spatial beta diversity with pairwise Bray-Curtis dissimilarity indices and Mantel tests, and diversity-biomass relationships with generalized linear models. The effect of environment on diatom communities was context-dependent, and different factors controlled communities along different gradients. Diversity varied along gradients and correlated with salinity in a U-shaped way. Beta diversity followed a general pattern of high taxonomic but low functional beta diversity along all gradients. Relationships between diatom diversity and ecosystem biomass were weak along all gradients. These results suggest that although the regional diversity of diatoms seems resilient, environmental change is likely to modify the local diversity of diatom communities. Finding out how these changes will affect ecosystem functioning requires further investigation.

Anthropogenic impact on a seacoast landscape during the last 1300 years in central Latvia, Northeastern Europe

Article

Mar 2023

Human‐induced activities around Lake Lilaste in the central Latvian sandy coastal area have been reconstructed over a 1300‐year period. We use a combination of well‐established geoarchaeological research methods ( ¹⁴ C dating, pollen, nonpollen palynomorphs, REVEALS modeling, diatoms, C/N ratio, magnetic susceptibility, loss on ignition) to study the human impact on the environment. Historical context aids focus on records of resource (e.g., timber) exploitation in the area. The continuous record of human indicator pollen and agricultural landscape suggests this area was suitable for habitation well before the studied time period, likely due to the ecosystem services it provided. Our proxy‐based study, combined with historical background, reveals a significant human impact on the terrestrial environment since the 14th century. Deficiency of trees in the northern outskirts of Riga during the 17th–19th century was likely. Anthropogenic activity has led to both deforestation and change in species composition. Our paleo records indicate recognizable human‐driven legacy in current seacoast landscape.

Holocene relative water level and storminess variation recorded in the coastal peat bogs of the Vistula Lagoon, southern Baltic Sea-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)

Article

Full-text available

Oct 2022
QUATERNARY SCI REV

The history of regional sea-level changes is critically important for building global environmental reconstruction models and identifying major driving forces. The coastal peatlands located on the terraces of the Vistula Lagoon (Gulf of Gda nsk, southern Baltic Sea) are one of the most valuable, and not yet fully explored, archives of the regional history of sea-level and storminess changes during the middle and late Holocene. The comprehensive analysis of peat and gyttja allowed establishing radiocarbon calibrated time series of stable carbon isotope composition (d 13 C), pollen and diatom data. The results indicate that the sea-level increased from~20 to 8 m below present sea level between 9000 and 7000 yr b2k at an average rate of~6 mm/year. Around 5000 yr b2k, the sea-level was~2.5 m lower than at present, which indicates a decrease in the rate of sea-level rise to~2.75 mm/year between 7000 and 5000 yr b2k. During the last 5000 years, the sea-level had risen at~0.5 mm/year to the present position. Changes in brackish diatoms, Pediastrum sp. concentrations, and maxima of d 13 C suggest ten periods of increased rates of sea-level rise and storminess between 7000 and 1500 yr b2k. Increased sea-levels and stormy surges on the peat surface occurred mainly during cold periods or the periods of transitions. These observations are in good agreement with climate fluctuations in the Northern Hemisphere related to the variations in total regional solar irradiation.

Effects of the Ionic Liquid [BMIM]Cl on the Baltic Microphytobenthic Communities

Article

Full-text available

Sep 2022

Ionic liquids (IL) are regarded as the solution to the modern world’s need to create and use compounds that exhibit a range of desirable properties while having a low environmental impact. However, recent reports are shattering the image of ionic liquids as environmentally friendly substances, especially in relation to the aquatic environment, revealing their potentially toxic effects. To assess the potential environmental impact of ILs, we conducted an experiment involving 1-butyl-3-methylimidazolium chloride ([BMIM]Cl), a substance considered to be the least hazardous among the imidazolium chloride ILs, on Baltic microphytobenthic communities. Microphytobenthos collected from the environment was tested under controlled laboratory conditions, and both the cell counts and the chloroplast condition were used as endpoints. It was shown that [BMIM]Cl at concentrations of 10−3 and 10−2, considered safe based on a cumulative impact assessment, has a negative effect on the condition of the microalgal cells and causes a reduction in population size. Although, under the influence of [BMIM]Cl, only a small proportion of the species was eliminated from the communities, only two species among those important to the communities showed resistance to this compound and eventually began to dominate the communities.

Distribution of marine benthic diatoms on the coasts of the sea of Marmara and their responses to environmental variables

Article

Jul 2022
J MARINE SYST

The Sea of Marmara, located in northwest Turkey, comprises challenging environmental conditions and is an important bridge between the Black Sea and the Aegean Sea. In this study, we assessed the trophic situation of the coasts of the Sea of Marmara using the benthic diatom composition and their relation to the environmental variables in the spring and autumn of 2019 and 2020. A total of 120 samples were collected and 452 species were observed; Navicula Bory and Nitzschia Hassal were represented with the highest numbers of taxa. Analysis of Similarity (ANOSIM) revealed that diatom communities differed significantly between the spring-autumn periods and years. Canonical Correspondence Analysis (CCA) showed that diatoms grouped underwater temperature, salinity, dissolved oxygen, and TIN influence. TRIX observations revealed a highly mesotrophic-eutrophic status along the coasts. Our study contributes to the knowledge of diatom diversity, distribution and community changes in spring and autumn on the coasts Sea of Marmara. Our findings suggest that marine benthic diatoms could be used as eutrophication indicators in the coastal waters for long-term monitoring with the support of environmental parameters.

Stochastic frontier analysis of catfish (Clarias gariepinus) aquaculture agribusiness for sustainable fisheries development: Evidence from Nigeria

Article

Full-text available

Jun 2021

Dicta Ovuevuraye Ogisi

Technical efficiency assessment and enhancement is critical to sustainable fisheries development in Nigeria. This study examines stochastic frontier of catfish aquaculture agribusiness for sustainable fisheries development. Purposive sampling technique was employed to select 110 catfish farmers in areas with high density catfish farms. Primary data were collected directly from catfish farmers using structured questionnaire. The analytical tools used were descriptive statistics, net farm income, stochastic frontier production function (SPF) and t-statistics. The result shows that most of the catfish farmers were young people within the productive age of 40-49 years. Catfish farmers had obtained various levels of formal education. Finding shows that feeds cost was the highest variable cost (72.75%). Feed had a positive and significant relationship (P<0.05) with catfish output. Mean technical efficiency is 53.49%. The estimated variance (δ2s=0.2125) is statistically significant (P<0.05), indicating that profit inefficiency is highly significant among catfish farmers. Estimated Gamma (γ) value of 0.26 implies that 26% of the total variation in catfish profit efficiency is due to the joint effect of technical inefficiency factors. The most significant efficiency factors are fish feed and pond size. The age and educational status of farmers are the most important determining factors of inefficiency in catfish production system. Lack of finance was the most serious constraint faced by catfish farmers. The study recommended that catfish farmers should form cooperative unions to facilitate their access to cooperative funding.

Copper chloride (II) effect on the composition and structure of marine microphytobenthic communities

Article

Full-text available

Jun 2022
ENVIRON MONIT ASSESS

To assess the temporary effects of the increased copper ion inflow on estuarine microphytobenthic communities, ecotoxicological tests were conducted using natural microphytobenthic assemblages obtained from an artificial substratum exposed to the waters of the southern Baltic Sea (Gulf of Gdańsk). The applied copper ion concentrations reflected permitted copper values established for waters of a good ecological status (2·10–5 g Cu·dm⁻³), and the maximum copper concentrations which, according to the current environmental regulations, are allowed to be discharged into the environment (2·10–3 g Cu·dm⁻³). In the studied communities, diverse responses of single species to CuCl2 exposure were recorded, including both growth inhibition and stimulatory effects as well. Despite the shift in the community composition and structure, total cell number remained at a similar level. The results of our investigations suggest that microphytobenthic assemblages are resistant to CuCl2 which is facilitated by the shift in the community composition resulting from the increasing cell number of copper tolerant species.

Etude de la pertinence des peuplements du microphytobenthos estuarien pour la mise en place d'un bio-indicateur de la qualité des eaux de transition

Technical Report

Full-text available

May 2022

In order to establish the ecological status of transitional water bodies, the European Water Framework Directive (WFD) is based on the evaluation of a certain number of biological quality elements, as well as physicochemical parameters supporting biology. As phytoplankton monitoring is not considered relevant due to the high turbidity characterizing the large estuaries in mainland France and overseas departments (French Guiana), the possibility of using microphytobenthos as a biological indicator of the ecological status of estuaries is being explored as a possible alternative. This activity report presents all the work carried out in 2021 within the framework of an OFB / University of Nantes agreement concerning estuarine microphytobenthos, summarizes all the work carried out since the start of the project and concludes the project. This work is divided into two parts. The first part concerns the micro-scale study (cm2) based on variations in the diversity and biomass of communities in relation to natural and anthropogenic pressures. The objective is to explore the possibility of developing a bio-indicator of the quality of estuarine water which draws inspiration from work carried out for freshwater. In 2021, we analyzed the data collected during the 2018 field campaigns in the estuaries of La Penzé, Morlaix, and the Seine. We related the data of microphytobenthos biomass estimated by the concentration of chlorophyll-a, also adding the data from 2016. We were able to identify the role of nutrients and secondarily macrofauna. The highest biomasses were observed for the site with the highest concentrations of ammonium, phosphates, and silicates. This confirmed the idea put forward in the article by Oiry & Barillé (2021) of microphytobenthos as a bioindicator of nutrient concentrations, in particular ammonium and nitrates. With this in mind, we wrote a manuscript describing an ecological niche-based method to identify which taxa have the best bioindication potential for nitrates and ammonium. The principle was outlined in last year's report (Oiry et al. 2020). We therefore now have the ability to assign an indicator value and ecological sensitivity to taxa of microphytobenthos by analogy with what is done for freshwater. We are, however, limited by the available dataset, which is 2-3 orders of magnitude smaller than what exists in freshwater. The range of environmental data, in particular nutrients, does not reach the values described for highly anthropized European estuaries. We, therefore, believe that we have laid the foundations to develop a bio-indicator based microphytobenthos communities. The last objective of the micro-scale actions was to update the database of benthic diatoms in mainland France. The current database includes 11,511 taxonomic entries found in 49 different references. The time period of the references used in this database now extends from 1888 to 2019. We have reconfigured the data in the Darwin Core Archive format, which is a standard for computer data on biodiversity. This will allow the database to be uploaded to the Global Biodiversity Information Facility (GBIF, https://www.gbif.org/) and to prepare a publication in the Biodiversity Data Journal (https://bdj.pensoft.net ). The second part concerns the macro-scale (km2) study of the microphytobenthos (MPB) using satellite remote sensing. We continued the observation of the MPB of the 42 Transitional Water Bodies (TWB) using the Sentinel-2 constellation of the European Space Agency which had been carried out for the year 2018 (Oiry & Barillé, 2021). This year we analyzed all the images available for 2019 and 2020, and therefore had 3 years of data. For each TWB and each date available, the biomass of MPB (estimated by the NDVI vegetation index) and the % cover of intertidal zones by MPB were recovered. Thus for each TWB, the frequency distribution of these two variables was obtained. We thus determined the 90 percentile (P90) of these two variables for each TWB. TWBs composed mainly of sandy sediments were treated separately from those composed mainly of muddy sediments. The median P90 for each estuary was compared to a reference P90 selected from estuaries that had the lowest median concentrations of nitrogenous nutrients from the Naïades platform (naiades.eaufrance.fr). An Ecological Quality Ratio (EQR) is thus proposed which combines the two metrics with a weighing principle. The EQR was applied to the 42 TWBs in mainland France.

Threshold effects of climate change on benthic diatom communities: Evaluating impacts of salinity and wind disturbance on functional traits and benthic biomass

Article

Full-text available

Feb 2022
SCI TOTAL ENVIRON

The responses of biotic communities and ecosystems to climate change may be abrupt and non-linear. Thus, resolving ecological threshold mechanisms is crucial for understanding the consequences of climate change and for improving environmental management. Here, we present a study on the threshold responses of benthic diatom communities that are an important component of all aquatic environments and strongly contribute to global primary production. We reach beyond the taxonomic perspective by focusing on the diversity and functions of diatom communities and benthic biomass along gradients of salinity and wind disturbance, whose climate-change-induced changes have been predicted to strongly affect biotic communities in the marine and brackish systems in the future. To improve the generality of our results, we examine three self-collected datasets from different spatial scales (6–830 km) and ecosystem types. We collected samples from rock pools or from littoral stones and studied taxonomic thresholds using Threshold Indicator Taxa Analysis (TITAN2). We investigated threshold responses of community diversity, community functions, and benthic biomass using t-tests and regression analysis. Our results indicated that decreasing salinity may result in increasing diversity but decreasing biomass of brackish communities, while the effects of increasing wind disturbance were contradictory among spatial scales. Benthic biomass correlated with the taxonomic and functional diversity, as well as with the body size distribution of communities, highlighting the importance of considering community functions and organismal size when predicting ecosystem functions. The most pronounced effects of decreasing salinity and increasing wind disturbance on community functions were changes in the abundance of low-profile diatom species, which, due to the high resilience of low-profile diatoms, may lead to changes in ecosystem functioning and resilience. To conclude, decreasing salinity and increasing wind disturbance may lead to threshold responses of biotic communities, and these changes may have profound effects on ecosystem functioning along marine coastal areas.

Studying biodiversity–ecosystem function relationships in experimental microcosms among islands

Article

Full-text available

Mar 2022
ECOLOGY

Ecological studies on islands have provided fundamental insights into the mechanisms underlying biodiversity of larger organisms, but we know little about the factors affecting island microbial biodiversity and ecosystem function. We conducted a field experiment on five Baltic Sea islands where we placed aquatic microcosms with different levels of salinity mimicking environmental stress and allowed diatoms to colonize the microcosms via the air. Using structural equation models (SEM), we investigated the interconnections among environmental and dispersal‐related factors, diatom biodiversity, and ecosystem productivity (represented by chlorophyll a concentration). We also tested whether the body size structure of the community influences productivity together with biodiversity. In SEMs, we found no relationship between species richness or evenness and productivity. However, productivity increased with increasing mean body size of species in the communities. The effects of environmental stress on both biodiversity and ecosystem productivity were highlighted as species richness and evenness declined, whereas productivity increased at the highest salinity levels. In addition to salinity, wind exposure affected both biodiversity metrics and productivity. This study provides new insights into microbial community assembly in a field experimental setting and the relationship between biodiversity and ecosystem function. Our results indicate that salinity presents a strong abiotic filter, leading to communities that may be species poor, yet comprise salinity‐tolerant and relatively productive species at high salinity. Our findings also emphasize the importance of mean community body size in mediating the effects of environmental conditions on productivity and suggest that this trait should be considered more broadly in biodiversity–ecosystem function studies.

Current state and problems of anthropogenic transformation of the ecosystem of Lake Ladoga in a changing climate

Book

Full-text available

Sep 2021

This monograph is a synthesis of the studies carried out over the past decade by the Institute of Limnology of the Russian Academy of Sciences and other organizations in the field of studying Lake Ladoga, which is the largest freshwater body in Europe. A number of important fundamental and applied problems have been solved to assess the anthropogenic transformation of the ecosystem of Lake Ladoga in a changing climate. It helps to expand understanding of the functioning and development of the lake itself and its catchment area. Paleolimnological studies allow to trace the history of the lake from the Late Ice Age and throughout the Holocene. Changes in the thermal regime of Ladoga due to climatic changes have been revealed. The impact of the catchment area on the lake ecosystem has been assessed. A new geomorphological map reflecting the structural features of the lake bottom has been created. Hydrological, hydrochemical, hydrobiological and toxicological studies allowed to assess the current state of the lake and its tributaries. Ecological risk zones in the water and catchment areas have been identified. They require regular monitoring to prevent catastrophic situations associated with the possible uncontrolled negative impact of these zones on the entire water body. Studies to assess microplastic pollution in the water area of the lake and its tributaries have been carried out. There is a significant progress in development and practical application of models of thermohydrodynamic processes and models of Lake Ladoga ecosystem. The principles and main directions for improving monitoring of Lake Ladoga have been formulated. The research results could be interesting for the general scientific community dealing with study, protection and rational use of water bodies.

Epipelic and epipsammic microalgae responses to environmental parameters: the Black Sea case study (the Gulf of Odesa, Ukraine)

Article

Dec 2021

Being part of autotrophic system in the sandy beaches epipelic and epipsammic microalgae play an essential role in primary production formation and transferring elements through the food chain. Acting as mixotrophs, they also participate in reduction of organic matter. But it is still less known about their response to pull of environmental factors. In particular, what is the range of main environmental parameters in sand supralittoral. The aim of this paper was to see the interaction between microalgae abundance and 14 environmental factors during field multifactoral experiment: 5 parameters describing sand grain composition, nutrients, temperature and salinity of water, hydrodynamics and water toxicity. We also analyzed the biodiversity of epipelic and epipsammic microalgae and their distribution in the North Western Black Sea. We revealed 76 taxa of microalgae: 39% epipelic and 27% epipsammic. The priority factor for psammon algal community in any season is size of sand grains and dissolved silicates. Other variables depend on the season: while in summer, inorganic nitrogen (nitrates and nitrites) affects the microphytes more intensively than others, in autumn it is replaced by organic nitrogen and silty fraction.

Late-Holocene relative sea-level changes and palaeoenvironment of the Pre-Viking Age ship burials in Salme, Saaremaa Island, eastern Baltic Sea

Article

Dec 2021

Two unique Pre-Viking Age ship burials were found from Salme village, Saaremaa Island, eastern Baltic Sea, containing remains of seven men in the smaller and 34 men in the larger ship. According to the archaeological interpretations, these ships belonged to a viking crew possibly from the Stockholm-Mälaren region, eastern Sweden. Geoarchaeological research was conducted in the area to reconstruct Late-Holocene relative sea-level (RSL) changes and shoreline displacement to provide environmental context to these burials. In this paper we present a Late-Holocene shore displacement curve for the Saaremaa Island and GIS-based palaeogeographic reconstructions for the Salme area. The curve shows an almost linear RSL fall from 5.5 to 0.8 m a.s.l. between 1000 BC and 1300 AD with an average rate of 2 mm/year. A slowdown in regression may be attributed to accelerated sea-level rise after the Little Ice Age and during the industrial period, being consistent with the tide-gauge measurements from the 20th century. Palaeogeographic reconstructions indicate the existence of a strait in the Salme area during the burial of the ships. The eastern part of the strait with water depth up to 2.8 m was about 80–100 m wide. The relatively steep and wind-protected shores in that part of the strait were probably the best places in the area for landing the viking ships. According to sedimentological evidence and diatom data, the narrowing of Salme palaeostrait occurred between 1270 and 1300 AD. Salme I and II ships were buried at 650–770 AD into the sandy-gravelly coastal deposits which had accumulated there in the open coastal zone about 710–450 years earlier. Reconstructions show that the ships were located about 2–2.5 m above coeval sea level and more than 100 m from the coastline. Thus, both ships were probably moved from the shore to the higher ground for burial.

New Records of Diatoms (Bacillariales, Rhopalodiales & Surirellales) with ultrastructure details from the Black Sea Coast of Turkey

Article

Full-text available

Nov 2021

Diatoms associated with the order Bacillariales, Rhopalodiales and Surirellales are well known to be present in marine and brackish waters. In this study, diatoms in the western Black Sea coasts of Turkey were investigated with ultrastructure details. Species belonging to the Bacillariales, Rhopalodiales and Surirellales were subject to light microscopy (LM) and scanning electron microscopy (SEM) analysis, and a total of twenty-four taxa were investigated. This study examines details on the morphology and biogeography of the taxa with remarks on their distribution in Turkey. The results revealed that four species were reported on the Turkish coasts for the first time. These species were Nitzschia liebethruthii, N. volvendirostrata, Epithemia guettingeri and Campylodiscus scalaris.

Вплив екологічних факторів на мікроводорості псамону на прикладі Одеської затоки (Чорне море, Україна)

Article

Full-text available

Sep 2021

Досліджено вплив екологічних факторів на морські мікроводорості піщаного узбережжя Одеської затоки. Незважаючи на достатню вивченість впливу фізичних та хімічних факторів середовища на мікроводорості, процеси, що відбуваються на піщаній супраліторалі в регіоні Чорного моря, потребують додаткових досліджень. В ході польового багатофакторного експерименту на узбережжі Одеської затоки досліджено взаємозалежність між чисельністю мікроводоростей та 14 екологічними факторами: низка параметрів, що визначають гранулометричний склад піску, біогенні елементи, температуру, солоність води, гідродинаміку та токсичність. Проаналізовано таксономічний склад мікроводоростей фітопсамону та їх розподіл у різних біотопах у холодноводний та тепловодний періоди. Пріоритетним фактором для угруповання фітопсамону в будь-який сезон є розмір піщинок та концентрація розчиненого кремнію. Інші параметри залежать від пори року: влітку сполуки мінерального азоту (нітрати та нітрити) є пріоритетним фактором, восени цю роль відіграють органічний азот та мулиста фракція піску.

Diatom sedimentary assemblages and Holocene pH reconstruction from the Canadian Arctic Archipelago's largest lake

Article

Jun 2021

The Arctic has warmed significantly over the past decades. However, the evolution of Arctic climate during the Holocene remains to be clarified in more detail, and regional factors controlling aquatic ecosystem evolution need to be better defined to grasp the sensitivity of lakes to rapid environmental change. Nettilling Lake was studied for changes in sedimentary diatom assemblages over the last 5 000 years. Lake water pH was reconstructed by applying a diatom-based lake water pH inference model. We hypothesized that the changes in diatom assemblages were driven by variations in lake water transparency and attendant water turbidity associated with the input of fine suspended solids from glacial meltwaters. Reduced underwater light resulted in greater abundance of planktonic over benthic taxa from ca. 5 000 to 3 000 yrs. cal. BP, followed by less turbid conditions and proliferation of benthic taxa during regional cooling. The lake water was slightly alkaline throughout the Holocene, ranging between pH 7.1 and 7.7. Our results support the notion that hydrological processes, dependent on climate variations, have a first-order influence on the regulation of the lake water pH through glacial meltwater inputs, which will likely continue to control the lake's long-term chemical and biological evolution. RÉSUMÉ

Exploring Multiple Aspects of Taxonomic and Functional Diversity in Microphytobenthic Communities: Effects of Environmental Gradients and Temporal Changes

Article

Full-text available

May 2021

Biodiversity has traditionally been quantified using taxonomic information but the importance of also considering its functional characteristics has recently gained an increasing attention among microorganisms. However, studies exploring multiple aspects of taxonomic and functional diversity and their temporal variations are scarce for diatoms, which is one of the most important microbial groups in aquatic ecosystems. Here, our aim was to examine the taxonomic and functional alpha and beta diversities of diatoms in a coastal rock pool system characterized by a naturally high environmental heterogeneity. We also investigated the temporal differences in the diversity patterns and drivers. The relationship between the species richness and functional dispersion was temporally coherent, such that species-poor communities tended to be functionally clustered. The trend between the species richness and taxonomic uniqueness of community composition was temporally inconsistent, changing from negative to non-significant over time. Conductivity or distance to the sea or both were key determinants of species richness, functional dispersion, and uniqueness of community composition. The increase of community dissimilarity with an increasing environmental distance was stronger for the taxonomic than the functional composition. Our results suggest that even minor decreases in the species richness may result in a lowered functional diversity and decreased ecosystem functioning. Species-poor ecosystems may, however, have unique species compositions and high contributions to regional biodiversity. Despite changing the species compositions along the environmental gradients, communities may remain to have a high functional similarity and robustness in the face of environmental changes. Our results highlight the advantage of considering multiple biodiversity metrics and incorporating a temporal component for a deeper understanding of the effects of environmental changes on microbial biodiversity.

Factors influencing biodiversity of three microbial groups within and among islands of the Baltic Sea

Article

Full-text available

Mar 2021

Islands provide ideal model systems to examine the factors influencing biodiversity, yet knowledge of microbial biodiversity on islands remains scarce. We collected a dataset from 101 rock pools along a freshwater to brackish water transition on islands of the Baltic Sea and investigated the patterns and drivers of community composition and species richness of diatoms, cyanobacteria, and non-cyanobacteria bacteria among islands. We also examined whether environmental heterogeneity increased beta diversity and species richness within islands. Among islands, the patterns in community composition were concordant among the microbial groups, with distinct changes along the freshwater–brackish gradient. The patterns in species richness were context dependent for each microbial group. In general, richness patterns were most strongly associated with nutrient concentrations or the distances to potential sources of immigrants, whereas no positive relationships between ecosystem size and richness were found. Within islands, environmental heterogeneity was positively correlated with beta diversity of each microbial group, but not species richness. Our findings provide novel insights into the factors influencing microbial biodiversity. The results suggest that island microbial biodiversity patterns are influenced by species sorting and dispersal-related mechanisms and highlight the importance of environmental heterogeneity for beta diversity.

Ecotoxicological Studies on the Effect of Roundup® (Glyphosate Formulation) on Marine Benthic Microalgae

Article

Full-text available

Jan 2021
Int J Environ Res Publ Health

Glyphosate is a very effective herbicide and the main active ingredient in Roundup®—the most extensively used herbicide in the world. Since glyphosate is highly water soluble it reaches water bodies easily in surface water runoff. This prompted us to undertake an experiment to evaluate the effects of glyphosate in Roundup® on natural communities of marine microphytobenthos. Microphytobenthos communities were obtained from the environment, and after transporting them to the laboratory and acclimatizing them, they were tested under controlled conditions. Changes in microphytobenthos composition and structure and the deteriorating condition of the cells of community-forming organisms (assessed by analyzing changes in chloroplast shape) were used to assess the impact of Roundup® on endpoints. The tests indicated that microphytobenthic communities were relatively resistant to herbicide. The species richness of the communities probably enabled them to rebuild effectively. Sensitive species were replaced by those more tolerant of glyphosate. Only at the highest glyphosate concentration (8.5 g·dm −3) tested was a strong negative effect noted that limited community abundance and eliminated some of the organisms. The dominant diatoms in the communities were replaced by intensively developing cyanobacteria; which ultimately comprised nearly 60% of all the cells observed in the communities.

Checklist of marine diatoms from the Turkish coastal waters with updated nomenclature

Article

Full-text available

Jan 2021

Marine diatom research in the coastal waters of Turkey started nearly two centuries ago. In the last decades, in-creasing numbers of contri-butions extended the knowledge of the marine phytoplankton. While sev-eral studies dedicated to planktonic forms and the checklists published con-cerning on the phytoplank-ton, relatively low numbers of benthic diatom studies were performed. Therefore, this is the first detailed list of the marine diatoms in-cluding both planktonic and benthic forms in Turkish coasts. This paper brings up the checklist of the past re-search referring to the au-thors in the last two centu-ries within the scope of the latest nomenclature. A total of 767 taxa (species, varie-ties and forms) belonging to 183 genera were listed. This study focussed into the study areas according to the reviewed literature and showed that many areas are yet to be investigated.

Diatoms in Estuaries and Tidal Marshes

Article

Full-text available

Oct 2007

Scott W. Starratt

Diatoms from estuarine and marsh sediments can be used to evaluate a number of geological processes. Information on salinity, elevation, and substrate derived from modern assemblages have been used to determine local and regional Holocene sea level history, identify seismic and tsunami events, and aid in the recognition of regional variations in precipitation. In order to apply diatoms to these questions, it is necessary to have a detailed knowledge of the ecology of marine, brackish, and freshwater taxa, as well as an understanding of the taphonomic processes that determine the final diatom assemblage. The potential for studies of pre-Holocene estuarine depositional systems is largely limited by the availability of study sites.

Diversity and distribution across a large environmental and spatial gradient: Evaluating the taxonomic and functional turnover, transitions and environmental drivers of benthic diatom communities

Article

Sep 2020
GLOBAL ECOL BIOGEOGR

Aim Global biodiversity loss has raised interest in understanding variation in diversity at different scales. In particular, studies conducted across large spatial gradients are crucial, because they can increase perspectives on how ecological patterns change relative to environmental factors and facilitate predictions of possible responses to environmental change. We explored the full extent of a brackish sea to test the hypotheses that: (a) benthic communities are defined by the limited ranges of species, controlled by varying drivers along a large environmental gradient; (b) the responses of taxonomic and functional community composition and turnover to the environmental gradient are different, thus highlighting the need to include both measures in ecological studies; and (c) diversity reaches the minimum at intermediate salinities (Remane curve) owing to the low adaptation of freshwater and marine species. Location A large environmental and spatial gradient spanning the entire Swedish coastline (c. 2,300 km; salinity 1.2–27.6), the Baltic Sea. Time period August 2018. Major taxa studied Benthic diatoms. Methods We assessed environmental drivers for the communities and calculated the taxonomic and functional alpha and beta diversity along the gradient. We also compared the taxonomic and functional composition and diversity of communities among areas with different salinity. Results We found support for the hypothesis of limited species ranges, because taxonomic beta diversity, mainly induced by changes in salinity and climate, was high, whereas functional beta diversity remained considerably lower, and the composition and diversity of communities, in addition to environmental drivers controlling the communities, differed between regions with different salinity. The lowest taxonomic diversity was found at intermediate salinities of 5–6. Main conclusions These findings advance understanding of large‐scale patterns of benthic diversity, emphasize the importance of large gradient studies for a better understanding of general ecological patterns and highlight the vulnerability of brackish water ecosystems as ecologically important tipping‐point realms.

Biodiversity Loss Threatens the Current Functional Similarity of Beta Diversity in Benthic Diatom Communities

Article

Full-text available

Feb 2021
MICROB ECOL

The global biodiversity loss has increased the need to understand the effects of decreasing diversity, but our knowledge on how species loss will affect the functioning of communities and ecosystems is still very limited. Here, the levels of taxonomic and functional beta diversity and the effect of species loss on functional beta diversity were investigated in an estuary that provides a naturally steep environmental gradient. The study was conducted using diatoms that are among the most important microorganisms in all aquatic ecosystems and globally account for 40% of marine primary production. Along the estuary, the taxonomic beta diversity of diatom communities was high (Bray-Curtis taxonomic similarity 0.044) and strongly controlled by the environment, particularly wind exposure, salinity, and temperature. In contrast, the functional beta diversity was low (Bray-Curtis functional similarity 0.658) and much less controlled by the environment. Thus, the diatom communities stayed functionally almost similar despite large changes in species composition and environment. This may indicate that, through high taxonomic diversity and redundancy in functions, microorganisms provide an insurance effect against environmental change. However, when studying the effect of decreasing species richness on functional similarity of communities, simulated species loss to 45% of the current species richness decreased functional similarity significantly. This suggests that decreasing species richness may increase variability and reduce the stability and resilience of communities. These results highlight the importance of high taxonomic biodiversity for the stable functioning of benthic communities.

Diatoms in tsunami deposits

Chapter

Full-text available

Jul 2020

Diatoms found within widespread sand beds deposited by tsunamis provide the framework for some of the most detailed historical and long-term (centuries to millennia) earthquake and tsunami reconstructions. In this chapter, we explore how the salinity preferences, life forms, and valve structures of diatoms are particularly useful for identifying tsunami sands within a variety of low-energy coastal environments around the world. We discuss the highly variable "signature" of diatoms within tsunami deposits and describe instances where clearly anomalous, allochthonous marine and brackish diatoms within tsunami deposits help support a marine incursion. We highlight how the fragmentation and sorting of diatom valves may provide evidence of high-energy transport during the rapid, turbulent flow of a tsunami; the potential use of diatoms to estimate tsunami runup beyond the landward limit of sedimentation; and the challenges in differentiating tsunami from storm deposits using diatoms.

Étude de la pertinence du suivi des peuplements du microphytobenthos estuarien. Final report 2018

Technical Report

Full-text available

Jan 2018

In order to establish the ecological status of water bodies, the European Water Framework Directive (WFD) is based on the evaluation of a number of biological quality elements, as well as physical parameters supporting the biology. In estuaries, phytoplankton monitoring was not considered relevant because of the high turbidity characterizing the large metropolitan estuaries and the French overseas departments (Guyana). In this work, we considered the possibility of using microphytobenthos (MPB) as a biological indicator of the ecological status of estuaries. This activity report summarizes the actions undertaken in 2017 under an AFB / Université de Nantes convention, which is structured around two main axes: the first axis is based on the analysis of the composition of MPB assemblages, and involves studying changes in MPB structure along disturbance gradients to develop a bioindicator. Assemblages are collected using micro-scale cores along transects positioned in the poly-haline portion of an estuary. This report summarizes the main results obtained during the field campaigns undertaken on the Loire estuary in the spring and autumn of 2016. The MPB diversity analysis are supplemented by measurements of biotic variables (meiofauna, macrofauna) and abiotics (PAHs, heavy metals, nutrients). This first axis also includes the development of a historical database based on the collections of Tempère and Peragallo, published between 1889 and 1915, as well as on the atlas of benthic marine diatoms of the French coastlines of Peragallo & Peragallo (1897- 1908). The database was completed in 2017 with more recent data from publications, dissertations, and reports. The second axis corresponds to a macro-scale study on the analysis of spatial distribution and biomass of MPB at the scale of an entire estuary by remote sensing. The objective is to develop a metric derived from data collected at macroscale. We began to develop the method for the Loire estuary while considering the possibility of applying it to the 42 estuaries and bays identified as transitional waters in metropolitan France. For this, we estimated the potential of different multispectral sensors to map microphytobenthos for estuaries of varying size, taking into account their spatial and spectral resolution.

Stable Seasonal and Annual Alpha Diversity of Benthic Diatom Communities Despite Changing Community Composition

Article

Full-text available

Feb 2020

The global biodiversity loss has raised interest in the different facets of diversity, and the importance of diversity for ecosystem functions has been recognized. However, our knowledge on seasonal and inter-annual variation in the composition and diversity of communities is still poor. Here, we investigated the seasonal and inter-annual changes in taxonomic and functional community composition and diversity of benthic diatoms in a coastal habitat of the northern Baltic Sea, where seasonal and inter-annual variation of climate is pronounced. We found that the taxonomic and functional alpha diversity remained stable at seasonal and inter-annual level despite strong changes in community composition. However, alpha diversity decreased during an exceptionally warm winter possibly due to disturbances induced by the lack of ice. This may suggest that climate warming and consequently limited ice cover will affect the diversity of benthic communities.

Sedimentary record of historical extreme storm surges on the Gulf of Gdańsk coast, Baltic Sea

Article

Jan 2020
MAR GEOL

The Baltic Sea is commonly viewed as a region with a low frequency of coastal hazards such as tsunamis or extreme storm surges. However, historical sources indicate that in the past, several catastrophic storm surges resulted in coastal floods and related casualties. Their sedimentological records and reconstructions of paleostorminess were so far studied mainly in the westernmost (Denmark) and easternmost (Estonia) parts of the Baltic Sea. The present study focus on southern Baltic coast (Gulf of Gdańsk), where storm surge sedimentary deposits left within coastal peatlands were investigated, and related to historical record in order to compare recent risk estimations and predictions of storm surge levels to geological data. To achieve this aim, the collected sediment cores were subjected to sedimentological, grain size, and diatom analyses, plus 137Cs, 210Pb, and 14C datings. Two types of sandy event deposits were identified, and interpreted to be storm deposits formed under an inundation regime and overwash regime, respectively. The deposits formed under the inundation regime were characterised by an erosional lower boundary, massive structure and presence of rip-up clasts of underlying sediments, whereas the sediments formed under the overwash regime were low-angle planar cross-stratified medium sands with intercalations of massive fine sand. The recognized sandy storm deposits were dated mainly to the Little Ice Age period (XVIth–XIXth centuries). They were most likely left during the historical storms of AD1825, AD1872, and AD1914. It extends the sedimentary record of known historical events as mainly storms from AD1497 and AD1872 were reported previously from Baltic Sea. Notably, none of the historical storm events during the past 100-year period have formed a distinguishable sedimentary record. These findings clearly show that risk models and storm return period predictions, which are based on instrumental measurements from the last century, should also include geological evidence. The strongest storm surges from the past century may not be adequate reference of a worst case scenario.

The Impacts of Ecosystem Hypertrophication and Climate Changes on Thrive of the Jellyfish in Shatt Al-Basrah Canal

Article

Full-text available

Sep 2019

The present study (i.e. the first study in Iraqi waters) identified the causes of reproduction and excessive growth of the jellyfish, which locally known as thagolol, of the type (Catostylus perezi) in the region of Shatt Al-Basrah canal - west of Basrah city. The reproduction and excessive growth of jellyfish occurs in many estuaries and coastal areas in the world, which is a recurring global problem in the context of climate change. The conducted study was included measurements of dissolved oxygen, electrical conductivity, total dissolved solids, pH, temperature, nitrates, phosphate, quality and quantity of phytoplankton during the dominant of :the northwest winds; the neap tide and during a full tidal periods in October of 2018 and March of 2019. The results showed that there were thrive of jellyfish by huge numbers in Shatt Al-Basrah canal. The physical; chemical and biological causes (i.e., the local causes), were identified, namely: (1) salinity, (2) water column temperature stratification in the context of climate change, (3) an excessive increase in the concentrations of nitrate and phosphate, (4) abundance of phytoplankton (i.e. dinoflagellate), including Protoperidinium sp. and Alexandrium sp.; and (5) overfishing. Hence, the absence of any of these factors will lead to the absence of this type of jellyfish.

Photosynthesis and Respiration of Baltic Sea Benthic Diatoms to Changing Environmental Conditions and Growth Responses of Selected Species as Affected by an Adjacent Peatland (Hütelmoor)

Article

Full-text available

Jul 2019

Eight benthic diatom taxa (Actinocyclus octonarius, Melosira moniliformis, Halamphora sp. 1, Halamphora sp. 2, Navicula perminuta, Navicula phyllepta, Nitzschia dubiiformis, Nitzschia pusilla) were isolated from sediments sampled in the southern coastal brackish Baltic Sea and established as unialgal cultures. The coastal shallow water sampling area lies close to a fen peat site (Hütelmoor) and both are connected through an underground peat layer, which might facilitate organic matter and nutrient fluxes along the terrestrial-marine gradient. The photosynthetic performance of these diatoms was measured at different photon fluence rates (0–1200 μmol photons m–2 s–1, always recorded at 20°C) and different temperatures (5–40°C, always measured at saturating ∼270 μmol photons m–2 s–1), resulting in light saturation points between 32 and 151 μmol photons m–2 s–1 and maximum net primary production rates of 23–144 μmol O2 mg–1 Chl a h–1. None of the species showed severe photoinhibition, and hence all displayed a high photo-physiological plasticity. Photosynthetic oxygen evolution and respirational oxygen consumption between 5 and 40°C revealed eurythermal traits for half of the studied taxa as photosynthetic efficiency was at least 20% of the maximum values at the extreme temperatures. The remaining taxa also indicated eurythermal characteristics, however, photosynthetic efficiency of at least 20% was at a narrower temperature range [5 (10) °C to 30 (35) °C]. Species-specific optimum temperatures for photosynthesis (15–30°C) were always lower compared to respiration (25–40°C). Actinocyclus octonarius and Nitzschia dubiiformis were grown in different defined media, some enriched with Hütelmoor water to test for possible effects of organic components. Hütelmoor water media stimulated growth of both diatom species when kept in a light dark cycle. Actinocyclus octonarius particularly grew in darkness in Hütelmoor water media, pointing to heterotrophic capabilities. The benthic diatoms studied are characterized by high photo-physiological plasticity and a broad temperature tolerance to maintain high primary production rates under wide environmental fluctuations. Organic carbon fluxes from the Hütelmoor into the Baltic Sea may support mixo- and/or heterotrophic growth of microphytobenthic communities. These are essential traits for living in a highly dynamic and variable shallow water environment at the coastal zone of the Baltic Sea.

Geological History of the Baltic: Volume 2: Evolution of the Baltic Sea

Book

Apr 2025

Leszek J. Kaszubowski

Rhoicosphenia johannessoniae (Bacillariophyceae), a new diatom from the Swedish coast of the Baltic Sea

Article

Sep 2023

Rhoicosphenia is a relatively small diatom genus regarding the number of species and the genus is characterized by its wedge-shaped frustule and heterovalvar structure. It is one of the few genera that is distributed in both marine and freshwater habitats. Few species of Rhoicosphenia are known along the stretched Baltic Sea coast of Sweden. The present study describes a new epiphytic species of Rhoicosphenia from the brackish water of Grisslehamn in the northern part of the Baltic Sea. Rhoicosphenia johannessoniae sp. nov. appears closely related to R. baltica, but differs in having more elongated and protracted base pole, densely packed areolae and a central area located below the central part of the valve. Detailed descriptions of the species based on light and electron microscopy, as well as a comparison with related taxa, are provided. The present work is part of a larger project aiming to study the littoral diatoms of Sweden. The finding of this species, together with other species previously described within the project, will add to our knowledge of the diatom assemblages of the Baltic Sea which seems to have a richer flora than earlier anticipated.

New insights into the association between epizoic diatoms and the sea turtle Chelonia mydas: new Mastogloia taxon (Bacillariophyceae) from Iran

Article

Mar 2023

Two epizoic species of Mastogloia, one of them a new taxon, have been found for the first time growing on the carapace of sea turtle Chelonia mydas from the Strait of Hormuz (Iran). Before this work, taxa belonging to the genus Mastogloia had never been identified as epibionts of C. mydas. The cleaned material of diatoms, collected from turtle carapaces was studied by light (LM) and scanning electron microscopy (SEM). Mastogloia hormuzensis sp. nov. is elliptical to linear-elliptical in valve view with rounded to slightly rostrate apices. Partecta are of different size and shape, with the larger one at the centre, and there is a very short partectal flange. The new epizoic diatom is unique in its morphology, and can be compared with Mastogloia exigua and M. pusilla, which show a similar combination of characters (e.g. the shape of areolae, type of partectal ring). Mastogloia hormuzensis sp. nov. fits into Hustedt’s species group Inaequales, to which it adds the feature of having a very short partecta flange. A second species, Mastogloia paradoxa, was also found living as epizoic for the first time.

Late Holocene Vistula River floods recorded in grain size distributions and diatom assemblages of marine sediments of the Gulf of Gdańsk (Baltic Sea)

Article

Full-text available

May 2023
PALAEOGEOGR PALAEOCL

During the large flood of the Vistula River in 2010, the riverine brackish water surface plume extended up to 70 km into the Gulf of Gdańsk (Baltic Sea), leaving a thin layer of medium-grained sand deposits. It inspired a search for palaeoflood records in marine sediments. Thus, we aimed to identify the most useful flood indicators and apply them to reveal palaeoflood records in sediment cores from the Gulf of Gdańsk. The study is based on analyses of surface samples, collected during and one year after the 2010 flood, and two long sediment cores, which were subjected to high-resolution grain size, diatom, and geochemical analyses, while chronology was based on the combined AMS 14C, 210Pb and 137Cs dating. It was found that, in a water depth of less than 30 m, modern large flood deposits were not preserved after a year. Sediment cores retrieved from greater water depths (over 60 m) were composed of sandy mud, and most of the 1 cm thick sediment samples were characterized by unimodal grain size distribution. However, some of the samples were bimodal, with the additional mode in fine-grained fractions, which is interpreted to be the result of direct deposition from riverine flood surface water plume. The diatom assemblages revealed a moderate downcore variability, except for the intervals characterized by bimodal grain size distributions. They contained elevated amounts of benthic oligohalobous (freshwater) and decreased euhalobous and mesohalobous taxa, supporting the likely interpretation of these layers as deposited during river flood events. During the last c. 4 ka, a dozen major flood events were identified. However, their application to flood climate reconstruction is challenging because of relatively frequent and partly unknown changes in major river mouth positions in the past. We suggest that thin deposits of major floods left on the seafloor and subjected to further mixing maybe still recognized using a combination of high-resolution grain size distribution and diatom analyses supplemented by a good understanding of the depositional system history.

Reconstruction of the geological history of the Lithuanian Maritime Region from MIS 6 to MIS 3

Article

Full-text available

Jun 2021
QUATERN INT

The Lithuanian onshore section of the south-eastern Baltic Sea region, or the so-called Lithuanian Maritime Region (LMR) - a belt several tens of kilometres wide along the Baltic Sea coast - is characterised by a complicated Quaternary structure and many of unsolved problems related to stratigraphy and palaeogeography. The inter-till lacustrine sediments widespread in the middle part of the Pleistocene thickness play a key role in solving the mentioned problems. The primary inter-till sediments were attributed, as a single lithostratigraphic unit, to the late Saalian Glaciation (MIS 6, Pamarys Sub-Formation; according to the Lithuanian Quaternary Stratigraphic Scheme). Subsequent detailed investigations show that the investigated inter-till succession represents a more complicated sediment complex formed over a wide time interval from the Saalian ice sheet decay at the very end of MIS 6 to the beginning of severe climate cooling during MIS 4. This standpoint is confirmed by the results of a few series of OSL and IR-OSL datings of inter-till sediments, as well as by data of pollen and diatom analysis. The more detailed stratigraphic subdivision of the inter-till sedimentary complex offers a new significant insight into the regional stratigraphic scheme of the Quaternary. As a result of the mentioned investigations, a new original reconstruction of the palaeogeographic situation in the LMR during the MIS 6 - MIS 3 time span was carried out. The lowermost part of the investigated inter-till sediments, attributed to MIS 6, could be correlated with the third MIS 6 warming in Northern Eurasia about 155 ka ago. The reconstruction of the palaeoenvironmental changes starting from MIS 6 and lasting to MIS 3 shows that the Eemian Sea MIS 5e in age was absent in the LMR, while part of the south-eastern Baltic Sea region was covered by a continental ice sheet during MIS 4 and, possibly, the very beginning of MIS 3.

Diatom Record of Holocene Moisture Variability in the San Bernardino Mountains, California, USA

Chapter

Full-text available

Apr 2021

Lower Bear Lake, in the San Bernardino Mountains, contains a Holocene paleohydrology record for southern California. The diatom and sediment geochemistry record indicates that the region experienced a wet Early Holocene followed by a gradual decrease in precipitation, which was punctuated by four strong and five weak pluvial episodes. The Lower Bear Lake record is compared with that of Silver Lake, a Mojave River terminal lake with headwaters in the San Bernardino Mountains, which exhibited several pluvial events at roughly the same time. The comparison is extended to records in relative proximity to Bear Lake (Dry Lake, Lake Elsinore, and San Joaquin marsh) and to two lakes with headwaters in the Sierra Nevada (Tulare Lake and Owens Lake). All exhibit a wet Early and early Middle Holocene wet interval and gradual drying through the remainder of the Holocene but differ in the expression of the pluvial episodes observed at Lower Bear Lake. The pluvial episodes are likely the result of changes in the storm track that affects the frequency and magnitude of winter storms in the area. These episodes are controlled by complex oceanic and atmospheric interactions and may be the result of the synchronous interaction of several teleconnections.

Auxospore wall structure and postsexual valve morphology in Rhabdonema minutum Kützing

Article

Full-text available

Jun 2019

Several decades ago, three members of the araphid pennate genus Rhabdonema ( R. adriaticum , R. arcuatum , R. minutum ) were the first araphid diatoms studied using cultures and electron microscopical methods to determine auxospore structure and development. Of these, R. minutum was the least documented at that time. None have been reinvestigated until now. Here we present the structural elements of the mature auxospore and the initial and postsexual valve characteristics of R. minutum . Although in general the auxospore wall of this diatom is similar to that of the two other species examined (to the extent that they were documented), there are intriguing differences. Most unanticipated is the structure of the primary band of the longitudinal perizonium, which shows remarkable similarities to the raphid pennate diatom valve. The evolutionary implications of such a similarity are considered.

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Intercalibration and Distribution of Diatom Species in the Baltic Sea. Vol. 3

Abstract

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