Invited Review - Fight on Plankton! or, Phytoplankton Shape and Size as Adaptive Tools to Get Ahead in the Struggle for Life

2011

Abstract A renewed interest in investigating the relationships existing between body size and environmental variables is pervading ecological studies. Phytoplankton has a long tradition as model system in studies of community ecology and several research concepts were developed using these organisms. In this paper we try to review the relevance of analyzing the morphological features of phytoplankton in ecology. Starting with a brief account of allometric relationships existing in phytoplankton, we i) examine the physical context in which phytoplankton grow, and ii) highlight the role of their size in nutrient uptake, and that of their shape in light harvesting. Moreover, the way in which t…

Observations on mucus aggregates along Sicilian coasts during 1991–1992

1995

Abstract The results of some observations on gelatinous material accumulating on the sea ground and free floating in the water column along Sicilian coasts are reported. The phenomenon showed different development patterns moving from the Tyrrherian to the Jonian coast and to the Sicilian Channel. Moreover, in 1991, mucus aggregates in the Tyrrhenian sea showed a similar structure, behaviour and origin to those observed in the Adriatic sea, whereas, in 1992, only a massive growth of metaphytic threadlike algae, more or less producing gelatinous sheaths, occurred.

Steady-state assemblages in a Mediterranean hypertrophic reservoir. The role of Microcystis ecomorphological variability in maintaining an apparent e…

2003

Lake Arancio is a hypertrophicMediterranean man-made lake, located on the southern coast of Sicily. Its artificial origin and the climate make it a very dynamic environment, strongly characterised by very wide water-level fluctuations. These vertical water movements interfere with the thermal stability of the water body often causing the breaking of the thermocline in mid-summer. In addition, the summer level-decrease influences the nutrient dynamics and modifies the zmix/zeu ratio. All these modifications were observed to support a high environmental variability, which was reflected by the richness of its phytoplankton composition and by its dynamics. Nevertheless, an investigation carried…

Relationship between trophic state and plankton community structure in 21 Sicilian dam reservoirs

1994

The relationship between the trophic state of 21 Sicilian dam reservoirs and their taxonomic community structure of phytoplankton (87 taxa) as well as zooplankton (45 taxa) have been examined by means of cluster analysis performed using annual average biomass values. The phytoplankton community structure was closely connected with the trophic state of the reservoirs, whereas the zooplankton community structure was related to hydrological regimes peculiar to the individual water bodies and not to the trophic state. © 1994 Kluwer Academic Publishers.

Distribution and seasonal dynamics of Cryptomonads in Sicilian water bodies

2003

Several species with a relevant ecological importance belong to Cryptophyta. Nevertheless, species-level identification from microscopic observations is problematic, lacking recent taxonomic keys. In this study we report our observations on distribution and seasonal dynamics of Cryptomonads in 33 Sicilian water bodies, as well as the main taxonomical problems we encountered. Species of the genera Cryptomonas and Plagioselmis are the most common in the examined water bodies. Their biomass seasonal trends usually show a peak in late winter and early spring. In advanced spring, and also in summer, due to the higher grazing pressure, the Cryptomonads biomass reaches its lowest values. Moreover,…

Toxic cyanobacterial blooms in reservoirs under a semiarid Mediterranean climate: the magnification of a problem

2007

Sicilian reservoirs constitute the most important water resources available on the island. During summer 2001, the intense water utilization of Lake Arancio reservoir reduced the water level significantly. This coincided with the formation of intense blooms formed by the microcystin-producing cyanobacterium Microcystis aeruginosa. During summer 2003, Lake Arancio was continuously filled and the vertical stratification of the water column was maintained, resulting in 5-6 fold lower cell numbers of Microcystis aeruginosa. For both years a significant linear relationship between microcystin net production and Microcysytis cell division was observed, implying that Microcystis cell numbers can b…

Phytoplankton dynamics in permanent and temporary Mediterranean waters: is the game hard to play because of hydrological disturbance?

2012

Only few scientific investigations have been carried out, to our knowledge, on phytoplankton in Mediterranean temporary ponds. To test the hypothesis that climate forcing is the main factor affecting dynamics and structure of planktic algae in these peculiar ecosystems, and to assess the importance of human impacts on this basic component of the aquatic biota, phytoplankton structure and dynamics were analysed in two temporary, long lasting (9 months), ponds, and in a permanent one. The three studied water bodies can be classified as mesoeutrophic, which show extended macrophyte beds and are subjected to one or more human impacts, such as eutrophication, fish and plant introduction, and gar…

New national and regional bryophyte records, 44

2015

Syntrichia norvegica is a circumpolar arctic- montane species (Smith, 2004), rare at lower altitudes and in southern Europe (Frey et al., 2006). It is known from several south-eastern European countries (Sabovljevic et al., 2008) and now it is recorded for the first time in Croatia. Regarding its conservation status, S. norvegica is red listed in Great Britain (EN), Czech Republic (CR), Slovakia (VU), Bulgaria (NT), Hungary (DD), Romania (VU) and Estonia (VU) (Hodgetts, 2014). It was found in the northern Velebit Mountains, in an area with the most outstanding and extreme karst relief, with steep slopes, perpendicular rocks, screes and deep dolines. The locality is situated in the Pinus mug…

Red sky at night cyanobacteria delight: the role of climate in structuring phytoplankton assemblage in a shallow, Mediterranean lake (Biviere di Gela…

2009

The hypothesis that climate changes may strongly interfere with the peculiar hydrological patterns in the Mediterranean basin and alter the structure of the aquatic biota was tested in a shallow Sicilian lake. A phytoplankton survey, carried out monthly in the brackish and shallow Biviere di Gela, in 2005–2007, revealed a transformation in the structure of its phytoplankton assemblage as compared with similar data collected in 1987–1988. An analysis of the trends followed by precipitation and temperature over the last 40 years, showed reduced water inflows, due to increased air temperature and evapotranspiration rather than to a decrease in the amount of precipitation. A consequent reductio…

Ecological characterization and cladocerans, calanoid copepods and large branchiopods of temporary ponds in a Mediterranean island (Sicily, Southern …

2006

Temporary waters have been sporadically investigated in Sicily. These environments reflect the climatic features of the Mediterranean area with a winter ponding phase and a more or less prolonged dry period in summer. Their biota, especially those organisms strictly linked to aquatic environments and without any terrestrial life stage, have to exhibit special adaptations to survive the dry phases that are recurrent in such ecosystems. This study included more than 250 water bodies distributed on the whole Sicilian territory and on the small circum-Sicilian islands. This paper represents a first attempt to characterize Sicilian temporary waters from an ecological point of view and is mainly …

Eutrophication control by lime addition: A preliminary approach in Sicilian reservoirs

2003

Sicilian reservoirs, a vital resource for this densely populated island, are undergoing increased eutrophication processes, due to the lack of urban waste treatment plants and to intense agriculture. Massive blooms of toxic cyanobacteria represent one of the most obvious consequences, and can be dangerous for population health. The possibility of a fast, even if only short term, recovery of water quality through application of lime, was tested through analysis of ion dynamics in two reservoirs, to develop an `emergency plan', to counteract cyanobacterial blooms and to decrease the risk for human health. The results indicate that these water bodies are suitable for lime treatments, even thou…

Studies on Italian reservoirs

1992

The main morphometric and water quality characteristics of the 221 Italian reservoirs covering an area of at least 0.2 km2 is given. Most of the reservoirs are used for drinking water purposes, especially on the islands of Sicily and Sardinia, where the more important cases of eutrophication have been found. These situations are examined in greater detail, with regard to algal population dynamics, the phosphorus budget and the comparison between theoretical and experimental nutrients loads. -from Authors

Water-level fluctuations in Mediterranean reservoirs: Setting a dewatering threshold as a management tool to improve water quality

2005

Water-level fluctuations, often linked to seasonal climatic trends, are a natural phenomenon which occur in almost all aquatic ecosystems. In some climatic regions, as the Mediterranean one, they are particularly wide due to the occurrence of two well separated periods: the rainy winter and the almost completely dry summer. Precipitation is concentrated in the first period, whereas in the second strong evaporation losses take place. According to these climatic features, and to ensure a continuous supply of water throughout the year, man-made lakes store water during winter and are subjected to dewatering during summer to compensate the lack of precipitation. These ecosystems are thus charac…

Phytoplankton dynamics in two reservoirs with different trophic state (Lake Rosamarina and Lake Arancio, Sicily, Italy)

1998

Two man-made Sicilian lakes of differing trophic status were sampled weekly for a year, in order to compare their phytoplankton dynamics and to identify their driving factors. The water bodies store comparable volumes but the eutrophic Lake Arancio may be considered to be a shallow lake whereas the mesotrophic Lake Rosamarina is deep. The dynamics of their principal physical, chemical and biological features were analysed using, among others, Canonical Community Ordination. The results obtained suggest that increased nutrient availability causes an increase of phytoplankton biomass but no community change nor any alteration to the typical assemblages supported. The major influence in the mo…

Fight on plankton! Or, phytoplankton shape and size as adaptive tools to get ahead in the struggle for life

2011

A renewed interest in investigating the relationships existing between body size and environmental variables is pervading ecological studies. Phytoplankton has a long tradition as model system in studies of community ecology and several research concepts were developed using these organisms. In this paper we try to review the relevance of analyzing the morphological features of phytoplankton in ecology. Starting with a brief account of allometric relationships existing in phytoplankton, we i) examine the physical context in which phytoplankton grow, and ii) highlight the role of their size in nutrient uptake, and that of their shape in light harvesting. Moreover, the way in which the morpho…

Phytoplankton dynamics in a shallow, hypertrophic reservoir (Lake Arancio, Sicily)

1994

Phytoplankton abundance and composition in the hypertrophic man-made Lake Arancio was analyzed, based on a programme of weekly sampling from May 1990 to November 1991 and supported by measurements of limnological parameters. The highest value of phytoplankton biomass (78 mg l-1) was observed in October 1990, during a bloom of the desmid Closterium limneticum var. fallax, while the lowest (0.15 mg l-1) was measured in April 1991. During spring, autumn and winter 1990, species of the genus Closterium dominated the community, in the sequence: C. aciculare, C. limneticum var. fallax, C. limneticum. The summer community was more diverse with the predominance of organisms belonging to Chlorophyce…

Cladocera (Branchiopoda, Anomopoda, Ctenopoda, and Onychopoda) from Sicilian inland waters: an updated inventory

2005

An extensive survey aimed at updating and increasing the knowledge on species richness and distribution of Cladocera (Branchiopoda) in Sicily has been carried out in the period 2000-2004. More than 250 water bodies, mainly temporary, have been sampled on the whole Sicilian territory and the circum-Sicilian islands. This sampling effort led to the discovery of several species new to the fauna of the island and, coupled with a careful bibliographic review, allowed the realization of an updated checklist that includes 57 species definitely present on the island (only 33 were formerly known), and two more, whose actual presence in Sicily is dubious and needs confirmation. The chorological spect…

Distribution and seasonal dynamics of Cryptomonads in Sicilian water bodies

2003

Several species with a relevant ecological importance belong to Cryptophyta. Nevertheless, species-level identification from microscopic observations is problematic, lacking recent taxonomic keys. In this study we report our observations on distribution and seasonal dynamics of Cryptomonads in 33 Sicilian water bodies, as well as the main taxonomical problems we encountered. Species of the genera Cryptomonas and Plagioselmis are the most common in the examined water bodies. Their biomass seasonal trends usually show a peak in late winter and early spring. In advanced spring, and also in summer, due to the higher grazing pressure, the Cryptomonads biomass reaches its lowest values. Moreover,…

Le diatomee bentoniche del porto di Palermo

1979

Abstract Benthic diatoms in the harbour of Palermo (Sicily).—The first results of a systematic investigation on the benthic diatoms on the fouling settlements, at four selected sites in the harbour of Palermo, are reported. Samples of comparable areas have been examined either on the fouling of vertical walls of the wharfs or on asbestos panels vertically submerged at the same place for at least eighteen months. Seventy-seven species have been found. No marked taxonomic difference is evident between the populations on the stoneworks and those on the panels.

Steady-state assemblages in a Mediterranean hypertrophic reservoir. The role of Microcystis ecomorphological variability in maintaining an apparent e…

2003

Lake Arancio is a hypertrophic Mediterranean man-made lake, located on the southern coast of Sicily. Its artificial origin and the climate make it a very dynamic environment, strongly characterised by very wide water-level fluctuations. These vertical water movements interfere with the thermal stability of the water body often causing the breaking of the thermocline in mid-summer. In addition, the summer level-decrease influences the nutrient dynamics and modifies the zmix/zeu ratio. All these modifications were observed to support a high environmental variability, which was reflected by the richness of its phytoplankton composition and by its dynamics. Nevertheless, an investigation carrie…

Mixotrophic phytoplankton dynamics in a shallow Mediterranean water body: how to make a virtue out of necessity

2018

Mixotrophy is a combination of photosynthesis and direct access to organic carbon sources, mainly through osmotrophy or phagotrophy. This strategy is adopted by several, phylogenetically distinct, phytoplankton groups and is commonly occurring in marine, brackish and freshwater ecosystems. Traditionally, it has been put in relation to both scarcity of inorganic nutrients and poor light conditions. However, we observed blooms of the mixotrophic, toxic haptophyte Prymnesium parvum in different periods of the year and under variable resources availability. The analysis of a 6.5-year data set of phytoplankton weekly records from a Sicilian shallow lake (Biviere di Gela, south-eastern Sicily) al…

Phytoplankton dynamics and structure: a comparative analysis in natural and man-made water bodies of different trophic state

2000

Previous investigations on Sicilian man made lakes suggested that physical factors, along with the specific morphology and hydrology of the water body, are important in selecting phytoplankton species. In particular, the variations of the zmix/zeu ratio due to the operational procedure to which reservoirs are generally subject were recognised as a trigger allowing the assemblage shift. To investigate if these variations may be considered analogous to those occurring in natural lakes as trophic state and phytoplankton biomass increase, causing a transparency decrease and a contraction of the euphotic depth, phytoplankton were collected in two natural water bodies, one mesotrophic (Lake Bivie…

Phytoplankton colonization patterns. Is species richness depending on distance among freshwaters and on their connectivity?

2015

Phytoplankton assemblages in two Sicilian water bodies were compared to test the hypothesis that colonization events and the successful establishment of a new species in an aquatic ecosystem may depend on the number of water bodies in a given area and on their relative distance. The two ecosystems are both natural, shallow lakes and they are protected sites hosting a rich avifauna. Lake Biviere di Gela is located in an area with a high density of ponds, whereas Lake Pergusa is an isolated waterbody without other aquatic ecosystems in its surroundings. Both lakes had almost disappeared about 10 years ago because of the over-exploitation of their main inflows. They were therefore re-filled us…

Ecology and distribution of Calanoid Copepods in Sicilian inland waters (Italy)

2006

(2006). Ecology and distribution of calanoid copepods in Sicilian inland waters (Italy) SIL Proceedings, 1922-2010: Vol. 29, No. 5, pp. 2150-2156.

Contributo alla conoscenza della flora sommersa del porto di Pantelleria (Canale di Sicilia)

1978

Abstract Some data on the benthic flora of Pantelleria Harbour (Channel of Sicily, Mediterranean).—The benthic flora of the harbour of Pantelleria includes: 10 Myxophyceae, 56 Rhodophyceae, 44 Diatomeae, 19 Phaeophyceae, 18 Chlorophyceae and 2 Angiospermae. The Rh/Ph value (2.9) is in agreement with the values found from the open-sea. A chorological examination shows a dominance of Atlantic-Mediterranean species (54.36%).

How do freshwater organisms cross the “dry ocean”? A review on passive dispersal and colonization processes with a special focus on temporary ponds

2014

Lakes and ponds are scattered on Earth’s surface as islands in the ocean. The organisms inhabiting these ecosystems have thus developed strategies to pass the barrier represented by the surrounding land, to disperse and to colonize new environments. The evidences of a high potential for passive long-range dispersal of organisms producing resting stages inspired the idea that there were no real barriers to their actual dispersal, and that their distribution was only limited by the ecological characteristics of the available habitats. The development of genetic techniques allowed to criticize this view and revealed the existence of a more complex and diverse biological scenario governed by an…

Rhizosolenia clevei var. communis

2006

Asterolampra grevillei

2006

Asterolampra marylandica

2006

Cladocera (Branchiopoda: Anomopoda, Ctenopoda and Onychopoda) from Sicilian inland waters: updated inventory and conservational status

2005

Specie aliene invasive

2008

Zooplankton dynamics and conservation problems of a Mediterranean temporary pond

2009

Cianoficee

2006

Ceratium limulus

2006

Fotosintesi in ambienti estremi: la strategia vincente di un’alga microscopica.

2008

Carenze conoscitive, spunti per la ricerca, priorità

2014

Protoperidinium diabolus

2006

Behavioural trait of Ostreopsis ovata (Dinophyceae) in Mediterranean rock pools: the spider’s strategy

2007

Rhizosolenia imbricata

2006

Dinamica stagionale dei popolamenti fitoplanctonici nei pantani della R.N.O. Oasi faunistica di Vendicari (SR)

2006

Toxic cyanobacterial blooms in reservoirs under a semiarid Mediterranean climate: the enlargement of a problem

2006

Asparagopsis taxiformis (Delile) Trevisan (Rhodophyta) e Trichodesmium erythreum Ehrenberg (Cyanobacteria), due taxa algali tropicali identificati ne…

2004

100 milioni di Microcystis spp. + 5 Procambarus clarkii = 0 Emys trinacris; ovvero tossine, invasori ed estinzione nei Gorghi Tondi, laghi salmastri …

2007

Gruppi funzionali del fitoplancton come descrittori sintetici nel biomonitoraggio degli ambienti lentici.

2004

Trichodesmium

2006

Peculiarità comportamentale del dinoflagellato Ostreopsis ovata Fukuyo (Dinophyceae): la strategia del ragno.

2006

Setting a dewatering threshold in Mediterranean reservoirs as a mansagement tool to improve water quality

2004

Umbilicosphaera sibogae

2006

Conferma della presenza di Najas marina L. (Najadaceae, Alismatales) in Sicilia

2007

Il fitoplancton delle zone umide siciliane d'importanza internazionale: presenza dell'aptofita ittiotossica Prymnesium parvum Carter

2005

Criptoficee

2006

Emiliania huxleyi

2006

Pluriannual morphological variability of phytoplankton in a productive Mediterranean reservoir.

2005

Prima segnalazione in Italia di una cloraracniofita (Chlorarachniophyta): Chlorarachnion reptans Geitler

2007

C2. ANALISI TASSONOMICHE E CONTEGGIO

2014

I cianobatteri sono diffusi in moltissimi ambienti acquatici, dove possono produrre cianotossine con diversi profili tossicologici. Il presente rapporto riporta le linee guida per la gestione delle fioriture di cianobatteri nelle acque di balneazione, elaborate da un gruppo di esperti. La prima parte sintetizza le attuali conoscenze scientifiche su vari aspetti, fra cui la loro presenza nei laghi italiani, le caratteristiche chimiche e tossicologiche delle varie cianotossine, gli effetti osservati sulla salute dell’uomo e la valutazione del rischio. La seconda parte definisce le linee guida per prevenire effetti dannosi per la salute dei bagnanti e gestire il rischio associato alle fioritur…

Gonyaulax hyalina

2006

Toxic blooms in sicilian reservoirs

2006

Ceratium concilians

2006

Green Algae

2009

Ornithocercus magnificus

2006

Ceratium ranipes

2006

Phytoplankton colonization patterns and the abundance of suitable aquatic ecosystems: the importance of nestedness among freshwaters. 17th Workshop o…

2014

Species-poor and species-rich phytoplankton assemblages in two Sicilian water bodies (Lake Pergusa and Lake Biviere di Gela) were compared to test the hypothesis that the number of colonization events and the successful establishment of a new species in an aquatic ecosystem may depend on the number and nestedness of water bodies in a given area. The two ecosystems are both natural, shallow lakes and they are protected sites hosting a rich avifauna. Both the lakes had quite high conductivity values (> 2,500 μS cm-1) and both were re-filled with fresh waters (< 400 μS cm-1) after they had disappeared because of the over-exploitation of their main inflows to fulfill agriculture water-demand. H…

Charophytes for description and monitoring of inland waters in Sicily

2017

The island of Sicily, in the center of the Mediterranean basin, is a well-known biodiversity hotspot (Médail &amp; Quézel, 1997). Unfortunately, the knowledge of its charophyte flora is absolutely unsatisfactory. The few available data derive from some scattered phytosociological works and some articles published more than 100 years ago. According to the last national synthesis (Bazzichelli &amp; Abdelahad, 2009) a total of 19 Charophytes species should occur in the island, distributed in 4 genera: Chara L. (11), Nitella Agardh (5), Tolypella (A. Braun) A. Braun (2) and Lamprothamnium J. Groves (1). However an updated list of the species occurring in the island, together with their distribu…

Ceratium candelabrum

2006

Pluriannual morphological variability in a highly productive Mediterranean reservoir (Lake Arancio, southwestern Sicily)

2007

The progressive decrease in water quality experienced by the Mediterranean, nutrient rich reservoir, Lake Arancio (Southwestern Sicily, Italy), has been accompanied by modifications in both phytoplankton shape and size. Since nutrient concentrations are always far from being limiting, in the present paper attention was focussed on the effects exerted by physical constraints (e.g., mixing, light availability) on the morphological variation observed in phytoplankton. The surface-volume ratio and its product with the maximal linear dimension were chosen as morphological descriptors to trace the trajectories followed by the dominant morphotypes in Lake Arancio. One of these descriptors was comp…

Pseudosolenia calcar-avis

2006

First record of Cyanophora paradoxa (Glaucocystophyta) in Italy

2006

A7. SITUAZIONE NAZIONALE: CORPI IDRICI INTERESSATI DA CIANOBATTERI TOSSICI

2014

I cianobatteri sono diffusi in moltissimi ambienti acquatici, dove possono produrre cianotossine con diversi profili tossicologici. Il presente rapporto riporta le linee guida per la gestione delle fioriture di cianobatteri nelle acque di balneazione, elaborate da un gruppo di esperti. La prima parte sintetizza le attuali conoscenze scientifiche su vari aspetti, fra cui la loro presenza nei laghi italiani, le caratteristiche chimiche e tossicologiche delle varie cianotossine, gli effetti osservati sulla salute dell’uomo e la valutazione del rischio. La seconda parte definisce le linee guida per prevenire effetti dannosi per la salute dei bagnanti e gestire il rischio associato alle fioritur…

Importance of water-level fluctuation on population dynamics of cladocerans in a hypertrophic reservoir (Lake Arancio, south-west Sicily, Italy)

1997

During a period of three years (1990-1991 and 1993), we studied the population dynamics of planktonic cladocerans in a hypertrophic reservoir. Weekly sampling revealed that the five most common species followed a trend which reflects the peculiar hydrological characteristics of the reservoir and their key position in the pelagic food web. In particular, 1991 was characterized by a strong water inflow which probably interfered with the reproductive activities of the dominant fish population (Rutilus rubilio) and reduced the concentration of inedible planktonic algae allowing the development of small Chlorococcales. This event was associated with higher population densities of Daphnia hyalina…

Le acque lentiche temporanee siciliane e i loro popolamenti a crostacei entomostraci

2004

Dictyocha fibula

2006

Scyphosphera apsteinii

2006

Bloom Di Planktothrix rubescens (Cyanobacteria) e rischio tossico nei bacini artificiali siciliani

2006

Crustacean dynamics in two argillotrophic, temporary ponds (North-Western Sicily, Italy)

2004

Ceratocorys horrida

2006

Planktoniella sol

2006

Discosphaera tubifer

2006

Presenza di Cyanophora paradoxa Koršikov 1924 in un piccolo stagno temporaneo siciliano.

2004

Gonyaulax polygramma

2006

Note su un bloom di Prymnesium parvum Carter (Haptophyta) nel lago di Pergusa e sue conseguenza sulla fauna.

2008

Dal 17 febbraio ai primi giorni di marzo 2008 è stata registrata una morìa di centinaia di Carpe (Cyprinus carpio) nel Lago di Pergusa, in coincidenza di un’anomala colorazione giallastra delle acque ascrivibile ad un intenso bloom dell’aptofita ittiotossica Prymnesium parvum. La microalga manifesta comunemente bloom e tossicità in acque eutrofiche poco profonde, con salinità comprese fra 1 e 12 PSU. Il bloom tossico nel Lago Pergusa, per quanto determinato dalla complessa interazione di numerosi fattori ambientali, è essenzialmente connesso alle mutate condizioni di salinità del corpo idrico negli ultimi 5 anni (da >20 PSU a <5 PSU). Sebbene non abbia causato mortalità nelle popolazioni di…

How do phytoplankton biomass and functional groups react to environmental constraints? A comparison in two different Mediterranean ponds

2009

Grouping organisms into functional grouping represents a way to better understand how the environmental constrains act on these organisms through the analysis of peculiar features, usually morphological, shared by the set of species. Since groups (Coda) react to environmental constrains with an analogous response, this approach was adopted to compare the structure and the biomass of phytoplankton assemblages in two different Mediterranean ponds, one temporary and the other permanent. A phytoplankton survey, carried out monthly in the brackish and shallow Biviere di Gela in 2005-2007, revealed a deep transformation in the structure of its phytoplankton assemblage as compared with similar dat…