The Biodiversity of the Mediterranean Sea: Estimates, Patterns, and Threats

The Mediterranean Sea is a marine biodiversity hot spot. Here we combined an extensive literature analysis with expert opinions to update publicly available estimates of major taxa in this marine ecosystem and to revise and update several species lists. We also assessed overall spatial and temporal patterns of species diversity and identified major changes and threats. Our results listed approximately 17,000 marine species occurring in the Mediterranean Sea. However, our estimates of marine diversity are still incomplete as yet—undescribed species will be added in the future. Diversity for microbes is substantially underestimated, and the deep-sea areas and portions of the southern and eastern region are still poorly known. In addition, the invasion of alien species is a crucial factor that will continue to change the biodiversity of the Mediterranean, mainly in its eastern basin that can spread rapidly northwards and westwards due to the warming of the Mediterranean Sea. Spatial patterns showed a general decrease in biodiversity from northwestern to southeastern regions following a gradient of production, with some exceptions and caution due to gaps in our knowledge of the biota along the southern and eastern rims. Biodiversity was also generally higher in coastal areas and continental shelves, and decreases with depth. Temporal trends indicated that overexploitation and habitat loss have been the main human drivers of historical changes in biodiversity. At present, habitat loss and degradation, followed by fishing impacts, pollution, climate change, eutrophication, and the establishment of alien species are the most important threats and affect the greatest number of taxonomic groups. All these impacts are expected to grow in importance in the future, especially climate change and habitat degradation. The spatial identification of hot spots highlighted the ecological importance of most of the western Mediterranean shelves (and in particular, the Strait of Gibraltar and the adjacent Alboran Sea), western African coast, the Adriatic, and the Aegean Sea, which show high concentrations of endangered, threatened, or vulnerable species. The Levantine Basin, severely impacted by the invasion of species, is endangered as well

Oceans : the impact of global change on the sea

A phenomenon of exceptional importance such as global change and its multiple effects has been discussed in several Mètode monographs. In recent years, public concern about what we already perceive to be the greatest threat to humanity has not stopped growing; at the same time, the United Nations have proclaimed the period 2021-2030 as the Decade of Ocean Sciences for Sustainable Development, recognising the close relationship between the oceans, climate, and social welfare. The sea is a climate regulator and a reservoir of biodiversity, a source of food and other resources, a transport route, a cultural asset, and the driving force behind the tourism industry; it is also a natural hazard and, unfortunately, a dumping ground for waste and refuse

Transcriptome fingerprinting analysis: an approach to explore gene expression patterns in marine microbial communities

Microbial transcriptomics are providing new insights into the functional processes of microbial communities. However, analysis of each sample is still expensive and time consuming. A rapid and low cost method that would allow the identification of the most interesting samples for posterior in-depth metatranscriptomics analysis would be extremely useful. Here we present Transcriptome Fingerprinting Analysis (TFA) as an approach to fulfill this objective in microbial ecology studies. We have adapted the differential display technique for mRNA fingerprinting based on the PCR amplification of expressed transcripts to interrogate natural microbial eukaryotic communities. Unlike other techniques, TFA does not require prior knowledge of the mRNA sequences to be detected. We have used a set of arbitrary primers coupled with a fluorescence labeled primer targeting the poly(A) tail of the eukaryotic mRNA, with further detection of the resulting labeled cDNA products in an automated genetic analyzer. The output represented by electropherogram peak patterns allowed the comparison of a set of genes expressed at the time of sampling. TFA has been optimized by testing the sensitivity of the method for different initial RNA amounts, and the repeatability of the gene expression patterns with increasing time after sampling both with cultures and environmental samples. Results show that TFA is a promising approach to explore the dynamics of gene expression patterns in microbial communitiesMC-L was the recipient of an FPI fellowship from the Spanish Ministry of Science and Innovation. This work was funded by grant GEMMA (CTM2007- 63753-C02-01/MAR) from the Spanish Ministry of Science and Innovation. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscrip

Maps of the sampling location.

<p>(A) Map of northern Chile showing the areas where samples were taken: 24 in Ascotán, three in El Tatio, and 2 in Atacama. (B) Modified satellite image of Salar de Ascotán showing the location of sampling spots. The contours of As level in water was constructed using the Surfer software program (v.7.0, Golden Software, USA). Point P6 had the highest concentration in the water. Concentrations in sediments were higher in all cases.</p

Total [As] in the natural environments analyzed (black triangles for water samples [mg/L] and yellow triangles for sediment samples [mg/Kg]), and range of concentrations where the arsenic related genes could be found with different primer sets (Table 2).

<p>The presence of the different genes is indicated by shades of gray; absence by white.</p

Tree of the <i>arsC</i> genes used to select the sequences for primer design.

<p>The sequences targeted by each reported and designed primer set are enclosed in colored rectangles. See <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0078890#pone-0078890-t002" target="_blank">Table 2</a> for primer sequences. The tree was constructed by Neighbor-joining. Bootstrap values for 500 replicates are indicated at the nodes.</p

Systems sampled, date, coordinates, altitude and some physicochemical parameters.

*<p>Samples analyzes by DGGE.</p

Relative abundance of major taxonomic groups in clone libraries from two selected samples (P9 water and P4 sediment) with different total arsenic concentrations from Salar de Ascotán.

<p>Relative abundance of major taxonomic groups in clone libraries from two selected samples (P9 water and P4 sediment) with different total arsenic concentrations from Salar de Ascotán.</p

Primer sets used in this study for PCR amplification of several genes involved in the arsenic cycle.

1<p>Code used in the present paper.</p>2<p>Name used in the original publication.</p

El canvi climàtic i els oceans - Thalassa

En aquest reportatge de Thalassa es dóna veu als investigadors marins catalans que ens expliquen la relació de les seves investigacions amb l'escalfament climàtic. Un tema en què es coneixen moltes respostes, però que encara té obertes grans incògnites. Els oceans juguen un paper clau en el clima de la Terra i són els causants de què l'escalfament del planeta sigui un procés irreversible durant els pròxims mil anys. Els científics marins estan detectant canvis significatius a tots els oceans de la Terra, però encara desconeixen en part com reaccionarà el complex sistema oceànic a aquest canvi del clima induït per les activitats humanes des dels inicis de la revolució industrial. Avui ja se sap que gel marí de l'Àrtic desapareixerà durant els estius d'aquí a 50 anys, també se sap que els esculls tropicals del món estan en greu perill, que algunes formes de vida marina s'extingiran o canviaran de lloc, es modificaran les línies costaneres per la pujada del nivell del mar submergint illes i deltes. Actualment proliferen les investigacions marines per tot el món per intentar entendre el procés de canvi global i així poder preveure els riscos que comporta, tant per a la vida marina com per a les societats humanes. Per sort, el repte que planteja el problema global del canvi climàtic ha arribat en un moment històric en què l'home ja disposa d'eines globals d'observació com els satèl·lits orbitals o les xarxes de sensors que s'estan posant per tots els oceans. Un coneixement més profund del que succeeix als oceans és qüestió de temps, i encara que això no resoldrà el problema del canvi climàtic ajudarà a preveure les seves pitjors conseqüències, eliminant part dels riscos que comportaPeer reviewe