Epilithic diatom assemblages and environmental quality of the Su Gologone karst spring (centraleastern Sardinia, Italy)

Karst springs are considered among the most vulnerable groundwater-dependent ecosystems. Despite their ecological value and importance as strategic water sources, Mediterranean karst springs are still poorly investigated. The aim of this study was to analyse the epilithic diatom assemblages and to test their usefulness as indicators of environmental quality on the Su Gologone spring (central-eastern Sardinia, Italy), a biotope of great natural value and a precious source of drinking water. A total of 89 diatom taxa were found with 25 new records for Sardinian running waters. Species richness, Shannon-Wiener and Pielou indices showed good biotic integrity. The dominant taxa were alkaliphilous, halophobous-oligohalobous exigent, xeno-oligosaprobic and characteristic of oligotrophic waters. The eutrophication/pollution index − diatom based (EPI-D) and the Navicula Nitzschia Surirella indices indicated respectively an excellent/good biological water quality and a low physical disturbance. However, the biological and chemical oxygen demand, and the microbiological variables (E. coli, fecal and total coliforms) revealed an organic contamination of the water, although moderate. The judgment provided by the EPI-D should be verified after updating of the index. In fact, 10 taxa found in this study are not currently considered by the EPI-D method

Biological survey of lakes and reservoirs from Sardinia and Piedmont (Italy), a georeferenced dataset from the project LIFE INHABIT

We report a georeferenced dataset of a biological survey carried out in lakes and reservoirs in Piedmont and Sardinia regions (Italy), that includes fish fauna, macroinvertebrates, macrophytes, and phytoplankton. This survey was carried out to test the standardised protocols adopted with the National Decree 260/210 by the Italian Ministry of the Environment, Land and Sea for the assessment of the ecological status of lakes and the ecological potential of reservoirs for satisfying the requirements of the European Water Framework Directive (WFD) 2000/60/EC. Occurrence data have been uploaded to the Global Biodiversity Information Facility (GBIF)

Indici per la valutazione della qualit? ecologica dei laghi

Collection of methods to evaluate lake quality using biological element

Meta-analysis of multidecadal biodiversity trends in Europe

Local biodiversity trends over time are likely to be decoupled from global trends, as local processes may compensate or counteract global change. We analyze 161 long-term biological time series (15-91 years) collected across Europe, using a comprehensive dataset comprising similar to 6,200 marine, freshwater and terrestrial taxa. We test whether (i) local long-term biodiversity trends are consistent among biogeoregions, realms and taxonomic groups, and (ii) changes in biodiversity correlate with regional climate and local conditions. Our results reveal that local trends of abundance, richness and diversity differ among biogeoregions, realms and taxonomic groups, demonstrating that biodiversity changes at local scale are often complex and cannot be easily generalized. However, we find increases in richness and abundance with increasing temperature and naturalness as well as a clear spatial pattern in changes in community composition (i.e. temporal taxonomic turnover) in most biogeoregions of Northern and Eastern Europe. The global biodiversity decline might conceal complex local and group-specific trends. Here the authors report a quantitative synthesis of longterm biodiversity trends across Europe, showing how, despite overall increase in biodiversity metric and stability in abundance, trends differ between regions, ecosystem types, and taxa.peerReviewe

Planothidium marganaiensis G. G. Lai, Ector & C. E. Wetzel 2021, sp. nov.

<i>Planothidium marganaiensis</i> G.G.Lai, Ector & C.E.Wetzel <i>sp. nov.</i> (Figs 2–65) <p> <b>Light microscopy (Figs 2–57):—</b> Frustules in girdle view rectangular, mostly single or forming short chains (up to two cells), clearly bent in the middle (Figs 29 <b>–</b> 32). Valves elliptical to weakly lanceolate with convex margins and subrostrate or slightly protracted apices (never capitate). Valve dimensions (n=59): length 5.0–12.3 µm, width 2.8–4.0 µm. Rapheless valve (Figs 2–28): Axial area linear, narrow and straight, sometimes lanceolate and slightly expanded in the middle of the valve. Central area asymmetrical with a unilateral small horseshoe-shaped hyaline area presenting a cavum. On the opposite side, absence of shortened striae or presence of one to two slightly shortened striae. Striae weakly radiate throughout the entire valve, 11–14 in 10 µm, measured at the central part of the valve opposite to the unilateral expansion. Raphe valve (Figs 33–57): Axial area linear and narrow, slightly widened near the middle of the valve. Central area transapically rectangular to rounded, bordered by one to three shortened striae on each side, usually more distant than the others. Raphe branches straight with expanded, drop-like proximal raphe endings. Terminal raphe fissures not discernible in LM. Striae radiate throughout the entire valve, 11–14 in 10 µm.</p> <p> <b>Scanning electron microscopy (Figs 58–65):—</b> Rapheless valve (SV) (Figs 58–62): Valve surface with shallow, rounded to irregularly shaped depressions along the apical axis, mainly concentrated in the central area (Figs 58–60). Externally, striae multiseriate, composed of three to five rows of small same-sized round areolae (Figs 58–60). Striae continuing shortly onto the valve mantle, without interruption (Figs 58–59). Internally, cavum covered by a hood with a narrow aperture towards the mantle (Figs 61, 62). Raphe valve (RV) (Figs 63–65): Striae composed of three to five rows of rounded areolae, not extended over the valve mantle (Fig. 63). Virgae broader than striae, except near the apices. Externally, proximal raphe endings straight, terminating in expanded drop–like pores. Distal raphe fissures bent, continuing shortly onto the valve mantle (Fig. 63). Internally, striae sunken between raised virgae and composed of areolae covered by individual hymenes (Figs 64, 65). Central nodule raised (Fig. 65). Proximal raphe endings slightly deflected into opposite sides, terminating inconspicuously (Figs 64, 65). Distal raphe endings terminating on poorly developed helictoglossae, continuing shortly onto the valve mantle (Fig. 64).</p> <p> <b>Type:—</b> ITALY. Carbonia-Iglesias: San Giovanni cave at Domusnovas (Monte Acqua, Marganai massif), 190 m a.s.l., 39°20’13.4’’N; 008°37’37.1’’E, sampling dates 21 September 2016 and 31 January 2017, collected by Giuseppina Grazia Lai (designated here, holotype: slide no. BR- 4636 Meise Botanic Garden, Belgium. Specimen here depicted in Fig. 9).</p> <p> <b>Etymology:—</b> The name refers to the <i>Marganai</i> massif where the karst spring San Giovanni originates. Marganai (Marganái) (Iglesias)—It is an elongated mountain or a mountain of a small mountain chain: it is likely that its name is to be compared—not derived—with Lat. margo, -inis “margin” (Indo-European). Cfr. Marghine (Source: Pittau, 2013).</p>Published as part of <i>Lai, Giuseppina G., Ector, Luc, Padedda, Bachisio M. & Wetzel, Carlos E., 2021, Planothidium marganaiensis sp. nov. (Bacillariophyta), a new cavum-bearing species from a karst spring in south-western Sardinia (Italy), pp. 140-154 in Phytotaxa 489 (2)</i> on pages 143-146, DOI: 10.11646/phytotaxa.489.2.3, <a href="http://zenodo.org/record/5756790">http://zenodo.org/record/5756790</a&gt

Long-term experimental in situ farming of Crambe crambe (Demospongiae: Poecilosclerida)

Background The marine sponge Crambe crambe was chosen as an experimental model of sustainable shallow-water mariculture in the Sardinian Sea (Western Mediterranean) to provide biomass with high potential in applied research. Methods Explants were cultured in four long-term experiments (19 and 31 months at ca. 2.5 m depth), to determine the suitability of new culture techniques by testing substrata and seeding time (season), and monitoring survival and growth. Explants were excised and grown in an experimental plant close to the wild donor sponge population. Percentage growth rate (GR%) was measured in terms of surface cover area, and explant survival was monitored in situ by means of a digital photo camera. Results Explant survival was high throughout the trial, ranging from 78.57% to 92.85% on travertine tiles and from 50% to 71.42% on oyster shells. A few instances of sponge regression were observed. Explant cover area correlated positively with season on two substrata, i.e., tiles and shells. The surface cover area and GR% of explants were measured in the starting phase and monitored up to the end of the trial. High GR% values were observed both on tiles (>21%) and on oyster shells (>15%). Discussion The data on the behaviour and life-style of cultured fragments, together with an increase >2,400% in cover area, demonstrate that in situ aquaculture is a viable and sustainable method for the shallow-water biomass supply of Crambe crambe

Diatom biodiversity in karst springs of Mediterranean geographic areas with contrasting characteristics: islands vs mainland

Karst ecosystems are considered as priority environments for the protection of biodiversity on a global scale. This study provides a first comparative analysis of epilithic diatom flora from karst springs in two Mediterranean geographic areas (Spain and Italy) with contrasting characteristics (islands vs mainland). We investigated twenty-three springs with different anthropogenic impact levels once in the winter season between 2007 and 2017 (N = 23). A total of 176 diatom taxa (56 genera) were found of which 101 (44 genera) were observed in single sites. A general good biotic integrity was revealed by structural indices (species richness, diversity and evenness). However, crenophilous species were generally present and abundant in less impacted springs. Comparing islands and mainland, significant differences were found in species composition and diversity (H\u2019) based on multivariate analyses (global R = 0.610; p = 0.001) and t-test (t = 2.304; p = 0.031). Discharge and Cl 12 were the most significant variables in determining diatom assemblages. Our results confirm the role of springs as multiple ecotones and refuges for rare species and suggest that the geographic insularity may be an important factor in maintaining diatom biodiversity

Effects of warming on a Mediterranean phytoplankton community

Predicting the responses of organisms is a complex challenge especially when water temperature is expected to increase over the coming decades, as a result of global warming. In this work the effects of warming on phytoplankton communities were investigated. An indoor experiment was performed, where water from a Mediterranean lagoon was incubated at different temperatures. Three treatments were applied in triplicate incubation units: the control (11 °C), 3 °C increase (14 °C), and 6 °C increase (17 °C). Our results showed significant effects by warming on phytoplankton. The abundance of relatively smaller taxa (Chlorella sp. and Planktothrix agardhii–rubescens group) increased at 17 °C, whereas the abundance of relatively larger species (Cyclotella sp. and Thalassiosira sp.) decreased, compared with the control. This shift towards smaller taxa resulted in a higher total biomass but lower chlorophyll a concentrations at the highest temperature.Short communication.</p

Quantifying uncertainties in biologically-based water quality assessment: a pan-European analysis of lake phytoplankton community metrics

Lake phytoplankton are adopted world-wide as a sensitive indicator of water quality. European environmental legislation, the EU Water Framework Directive (WFD), formalises this, requiring the use of phytoplankton to assess the ecological status of lakes and coastal waters. Here we provide a rigorous assessment of a number of proposed phytoplankton metrics for assessing the ecological quality of European lakes, specifically in response to nutrient enrichment, or eutrophication, the most widespread pressure affecting lakes. To be useful indicators, metrics must have a small measurement error relative to the eutrophication signal we want them to represent among lakes of different nutrient status. An understanding of variability in metric scores among different locations around a lake, or due to sampling and analytical variability can also identify how best this measurement error is minimised. To quantify metric variability, we analyse data from a multi-scale field campaign of 32 European lakes, resolving the extent to which seven phytoplankton metrics (including chlorophyll a, the most widely used metric of lake quality) vary among lakes, among sampling locations within a lake and through sample replication and processing. We also relate these metrics to environmental variables, including total phosphorus concentration as an indicator of eutrophication. For all seven metrics, 65–96% of the variance in metric scores was among lakes, much higher than variability occurring due to sampling/sample processing. Using multi-model inference, there was strong support for relationships between among-lake variation in three metrics and differences in total phosphorus concentrations. Three of the metrics were also related to mean lake depth. Variability among locations within a lake was minimal (<4%), with sub-samples and analysts accounting for much of the within-lake metric variance. This indicates that a single sampling location is representative and suggests that sub-sample replication and standardisation of analyst procedures should result in increased precision of ecological assessments based upon these metrics. For three phytoplankton metrics being used in the WFD: chlorophyll a concentration, the Phytoplankton Trophic Index (PTI) and cyanobacterial biovolume, >85% of the variance in metric scores was among-lakes and total phosphorus concentration was well supported as a predictor of this variation. Based upon this study, we can recommend that these three proposed metrics can be considered sufficiently robust for the ecological status assessment of European lakes in WFD monitoring schemes