Lago Maggiore oligotrophication as seen from the long-term evolution of its phytoplankton taxonomic size structure

Kamenir, Yury; Morabito, Giuseppe; Goodman, Everard

doi:10.4081/jlimnol.2009.146

Cited by 31 publications

(20 citation statements)

References 31 publications

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“…Electron microscopy showed that these spaces were filled with electron dense fibrillar structures or globules similar to polyphosphate bodies (Kom arek and Albertano, 1994). It is interesting to observe that another species e Tychonema sequanum e was identified by microscopic methods in Lake Maggiore (Kamenir and Morabito, 2009). This taxon, however, has smaller dimensions (2.5e5 mm width) compared to T. bourrellyi.…”

Section: Discussionmentioning

confidence: 99%

Anatoxin-a producing Tychonema (Cyanobacteria) in European waterbodies

et al. 2015

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Keywords:Anatoxin a Tychonema Cell quotaPolyphasic approach Phylogenetic analysis European waterbodies a b s t r a c tIn order to identify the cyanobacterial species responsible of anatoxin a (ATX) production in Lake Garda (Northern Italy), an intensive isolation and culturing of filamentous cyano bacteria were established since 2014 from environmental samples. In this work, we report a detailed account of the strategy adopted, which led to the discovery of a new unexpected producer of ATX, Tychonema bourrellyi. So far, this species is the first documented example of cultured Oscillatoriales able to produce ATX isolated from pelagic freshwater ecosys tems. The isolated filaments were identified adopting a polyphasic approach, which included microscopic species identification, genetic characterisation and phylogenetic analyses based on 16S rRNA genes. The taxonomic identification was further confirmed by the high (>99%) rbcLX sequence similarities of the T. bourrellyi strains of Lake Garda with those deposited in DNA sequence databases. More than half of the isolates were shown to produce a significant amount of ATX, with cell quota ranging between 0.1 and 2.6 mg mm 3 , and 0.01 and 0.35 pg cell 1 . The toxic isolates were tested positive for anaC of the anatoxin a synthetase (ana) gene cluster. These findings were confirmed with the discovery of one ATX producing T. bourrellyi strain isolated in Norway. This strain and a further non ATXproducing Norwegian Tychonema bornetii strain tested positive for the presence of the anaF gene of the ana gene cluster. Conversely, none of the Italian and Norwegian Tychonema strains were positive for microcystins (MCs), which was also confirmed by the absence of mcyE PCR products in all the samples analysed. This work suggests that the only reliable strategy to identify cyanotoxins producers should be based on the isolation of strains and their identification with a polyphasic approach associated to a concurrent metabolomic profiling.

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Section: Discussionmentioning

confidence: 99%

Anatoxin-a producing Tychonema (Cyanobacteria) in European waterbodies

et al. 2015

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“…An increase in B. longimanus releases rotifers, especially large C. hippocrepis colonies, from competition with cladocerans (Hovius et al 2006;Manca 2011). In Lago Maggiore, abundance and mean size of phytoplankton cells decreases with restoration (Manca & Ruggiu 1998;Kamenir & Morabito 2009). While microphagous species ingest multiple food items no larger than ~15-20 μm, raptorials prefer larger particles (Pourriot 1977;Karabin 1985;Wallace et al 1989).…”

Section: Discussionmentioning

confidence: 99%

Response of rotifer functional groups to changing trophic state and crustacean community

Obertegger¹,

Manca²

2011

J Limnol

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“…Phytoplankton body size is also related to ecosystem functioning as it affects the transfer of energy through the food web as zooplankton grazers specialise on different algal sizes (Jansson et al, 2007). Following a more functional approach, a phytoplankton assemblage can be described in terms of size spectra (Kamenir & Morabito, 2009) or Morpho-Functional Groups (Reynolds et al, 2002;Salmaso & Padisák, 2007).…”

Section: Compositionmentioning

confidence: 99%

Strength and uncertainty of phytoplankton metrics for assessing eutrophication impacts in lakes

et al. 2012

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Contact CEH NORA team at noraceh@ceh.ac.ukThe NERC and CEH trademarks and logos ('the Trademarks') are registered trademarks of NERC in the UK and other countries, and may not be used without the prior written consent of the Trademark owner. AbstractPhytoplankton constitute a diverse array of short-lived organisms which derive their nutrients from the water column of lakes. These features make this community the most direct and earliest indicator of the impacts of changing nutrient conditions on lake ecosystems. It also makes them particularly suitable for measuring the success of restoration measures following reductions in nutrient loads. This paper integrates a large volume of work on a number of measures, or metrics, developed for using phytoplankton to assess the ecological status of European lakes, as required for the Water Framework Directive (WFD). It assesses the indicator strength of these metrics, specifically in relation to representing the impacts of eutrophication. It also examines how these measures vary naturally at different locations within a lake, as well as between lakes, and how much variability is associated with different replicate samples, different months within a year and between years. On the basis of this analysis, three of the strongest metrics (chlorophyll-a, Phytoplankton Trophic Index (PTI) & cyanobacterial biovolume) are recommended for use as robust measures for assessing the ecological quality of lakes in relation to nutrient enrichment pressures and a minimum recommended sampling frequency is provided for these three metrics.

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Lago Maggiore oligotrophication as seen from the long-term evolution of its phytoplankton taxonomic size structure

Abstract: ABSTRACT

Cited by 31 publications

References 31 publications

Anatoxin-a producing Tychonema (Cyanobacteria) in European waterbodies

Anatoxin-a producing Tychonema (Cyanobacteria) in European waterbodies

Response of rotifer functional groups to changing trophic state and crustacean community

Strength and uncertainty of phytoplankton metrics for assessing eutrophication impacts in lakes

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