Ocean acidification impacts on nitrogen fixation in the coastal western Mediterranean Sea

The effects of ocean acidification on nitrogen (N2) fixation rates and on the community composition of N2-fixing microbes (diazotrophs) were examined in coastal waters of the North-Western Mediterranean Sea. Nine experimental mesocosm enclosures of ∼50 m3 each were deployed for 20 days during June-July 2012 in the Bay of Calvi, Corsica, France. Three control mesocosms were maintained under ambient conditions of carbonate chemistry. The remainder were manipulated with CO2 saturated seawater to attain target amendments of pCO2 of 550, 650, 750, 850, 1000 and 1250 μatm. Rates of N2 fixation were elevated up to 10 times relative to control rates (2.00 ± 1.21 nmol L-1d-1) when pCO2 concentrations were >1000 μatm and pHT (total scale) < 7.74. Diazotrophic phylotypes commonly found in oligotrophic marine waters, including the Mediterranean, were not present at the onset of the experiment and therefore, the diazotroph community composition was characterised by amplifying partial nifH genes from the mesocosms. The diazotroph community was comprised primarily of cluster III nifH sequences (which include possible anaerobes), and proteobacterial (α and γ) sequences, in addition to small numbers of filamentous (or pseudo-filamentous) cyanobacterial phylotypes. The implication from this study is that there is some potential for elevated N2 fixation rates in the coastal western Mediterranean before the end of this century as a result of increasing ocean acidification. Observations made of variability in the diazotroph community composition could not be correlated with changes in carbon chemistry, which highlights the complexity of the relationship between ocean acidification and these keystone organisms.

Impacts of ocean acidification in a warming Mediterranean Sea: An overview

Mediterranean Sea fisheries supply significant local and international markets, based largely on small pelagic fish, artisanal fisheries and aquaculture of finfish (mainly seabass and seabream) and shellfish (mussels and oysters). Fisheries and aquaculture contribute to the economy of countries bordering this sea and provide food and employment to coastal communities employing ca 600,000 people. Increasing temperatures and heat wave frequency are causing stress and mortality in marine organisms and ocean acidification is expected to worsen these effects, especially for bivalves and coralligenous systems. Recruitment and seed production present possible bottlenecks for shellfish aquaculture in the future since early life stages are vulnerable to acidification and warming. Although adult finfish seem able to withstand the projected increases in seawater CO2, degradation of seabed habitats and increases in harmful blooms of algae and jellyfish might adversely affect fish stocks. Ocean acidification should therefore be factored into fisheries and aquaculture management plans. Rising CO2 levels are expected to reduce coastal biodiversity, altering ecosystem functioning and possibly impacting tourism being the Mediterranean the world’s most visited region. We recommend that ocean acidification is monitored in key areas of the Mediterranean Sea, with regular assessments of the likely socio-economic impacts to build adaptive strategies for the Mediterranean countries concerned.

Lamellibrachia anaximandrin. sp., a new vestimentiferan tubeworm (Annelida) from the Mediterranean, with notes on frenulate tubeworms from the same habitat

A new species of lamellibrachiid vestimentiferan, Lamellibrachia anaximandri n. sp., has been found in the Eastern Mediterranean, close to cold seeps of fluid carrying dissolved methane and sources of sulfide in superficial sediments. It occurs at about 1100 to 2100 m depth, on some of the mud volcanoes on the Anaximander Mountains, south of Turkey, on the Mediterranean Ridge, south of Crete, and on the Nile deep-sea fan. In addition, it has been obtained from rotting paper inside a sunken ship, torpedoed in 1915 and lying at 2800 m depth, southeast of Crete. Some frenulate pogonophores also occur on the mud volcanoes (including a species of Siboglinum resembling S. carpinei and tubes of other unidentified genera). The new Lamellibrachia is the first vestimentiferan species to be described from the Mediterranean. It differs from L. luymesi taken from the Gulf of Mexico population in the very weak development of collars on its tube and in having a smaller number of pairs of branchial lamellae in the branchial plume. Sequencing of the COI and the mt16S genes confirms a difference at the species level between the new species and L. luymesi, and a difference between these two species and four described species of Lamellibrachia from the Pacific Ocean. The largest individuals of L. anaximandri n. sp. may be many years old, but there are numerous young individuals at some sites, showing that favourable conditions are available for settlement and early growth. The development of the branchial plume in a series of young stages reveals that the sheath lamellae, which are characteristic of the genus Lamellibrachia, begin to form only after the establishment of several pairs of branchial lamellae. Examination of the adult trophosome by transmission electron microscopy shows Gram-negative bacteria without internal stacked membranes, indicating that the symbionts are most probably sulfide oxidizing.

Problems of dynamic in mediterranean forests

The mediterranean forest ecosystems constitute a complex unit which is marked off the Northern and middle European ones by its climate, ecology and management.The ecosystems are related to a climate with estival droughtlasting from 1 to 6 months and the peculiar species which constitute them are generally not worth much.The anthropic pressure exerts especially by grazing and moreover they have been stricken by dramatic fires for many decades. Their large variety related to the bioclimatic and edaphic heterogeneity of the region can explain why the data concerning their functioning and dynamics are still fragmentary. Besides, their ecological and pedological characteristics make uneasy the use of schemes and patterns designed for middle european forests.

Crisis Management in the Eastern Mediterranean (Implications for Policymakers)

This article examines Greek-Turkish crisis behaviour in the Eastern Mediterranean over the past two decades. Crises are first defined and classified, after which a number of common misperceptions are then addressed in light of recent experience. Three broad categories of foreign policy crises are analyzed: 1) those involving ethnically related minorities across the border; 2) those with 'alien' minorities within borders; and 3) those with third countries involving territories and resources. The article examines whether crises are simply elite-driven or partly endorsed and motivated by mass publics in both countries, and whether Greek-Turkish crisis behaviour reflects enduring ethnic rivalries, 'genuine' security interests, or domestic political needs and norms. The article draws upon the Greek-Turkish experience of the past two decades to illuminate contemporary dilemmas and issues which policymakers face in this region.

Isotope Hydrology of the Oldman River basin, southern Alberta, Canada

The partially semi-arid Oldman River basin (OMRB), located in southern Alberta (Canada), has an area of 28 200 km2, is forested in its western headwater part, and is used for agriculture in its eastern part. Hydrometric measurements indicate that flow in the Oldman River has decreased by ~34% between 1913 and 2003, and it is predicted that water withdrawals will increase in the next 20 years. The objective of this study was to determine whether isotope ratio measurements can provide further insight into the water dynamics of the Oldman River and its tributaries. Surface water samples were collected monthly between December 2000 and March 2003. Groundwater samples were taken from 58 wells during one-time sampling trips. Runoff within the OMRB is currently about 70 mm year-1, with a corresponding runoff ratio of 0Ð18. Seasonal flow characteristics are markedly different upstream and downstream of the Oldman River reservoir. Upstream, sharp increases in flow in late spring and early summer are followed by a rapid decrease to base flow levels. Downstream, a prolonged high flow peak is observed due to the storage effect of the Oldman River reservoir. The seasonal variation in the isotopic composition of surface water from upstream sites is small. This suggests that peak runoff is not predominantly generated by melting snow accumulated during the preceding winter, but mainly by relatively well-mixed young groundwater. A significant increase in the d18O and d2H values in the downstream part of the basin was observed. The increase in the isotopic values is partly due to surface water and groundwater influx with progressively higher d18O and d2H values in the eastern part, and partly due to evaporation. Hence, the combination of hydrometric data with isotope measurements yields valuable insights into the water dynamics in the OMRB that may be further refined with more intensive measurement programmes in the future.

Nitrogen budget for the Oldman River Basin, southern Alberta, Canada

The Oldman River Basin (OMRB), located in southern Alberta (Canada), with an area of 28,200 km2, is mainly forested in its western part and is used for intensive agriculture in its eastern part. The objective of this paper is to estimate the nitrogen (N) budget for the Oldman River Basin as a whole and its sub-basins, and to discuss differences in the N budget between various sub-basins. Better knowledge of the N budget in this watershed may be also utilized for understanding N dynamics in similar watersheds within semi-arid climatic regions. The model used is a mass balance spreadsheet model that takes into account N inputs and N export through surface water. During the last 120 years, anthropogenic N inputs to the OMRB have increased circa 40 fold. By the end of the 20th century, the OMRB received an annualN input of about 5174 kg N km-2 yr-1, whereas only about 25 kg N km-2 yr-1 were exported via riverine flow. For the sub-basins, annual N inputs ranged from 2516 to 19011 kg N km-2 yr-1, and annual N export via riverine flows varied between 6 and 277 kg N km-2 yr-1. Over 85% of total N inputs to the OMRB are due to anthropogenic activities, including manure (55%), synthetic fertilizer (27%), and N fixation on agricultural lands (4%). Sewage accounted for less than 1%, and N inputs from atmospheric deposition and fixation in forests represented 6 and 8% respectively. Despite increasing anthropogenic N inputs, N export with riverine flow currently accounts for only 1% of the inputs, indicating thatmost of theNinputs are currently retained in the OMRB or are re-emitted into the atmosphere.

Isotopic Assessment of Sources of Surface Water Nitrate within the Oldman River Basin, Southern Alberta, Canada

Concentrations and isotopic compositions of NO-3 from the Oldman River (OMR) and some of its tributaries (Alberta, Canada) have been determined on a monthly basis since December 2000 to assess temporal and spatial variations of riverine NO-3 sources within the OMR basin. For the OMR sites, NO-3 -N concentrations reached up to 0.34 mg L-1, d15N-NO-3 values varied between –0.3 and +13.8‰, and d18O-NO-3 values ranged from –10.0 to +5.7‰. For the tributary sites, NO-3 -N concentrations were as high as 8.81 mg L-1, d15N-NO-3 values varied between –2.5 and +23.4‰, and d18O-NO-3 values ranged from –15.2 to +3.4‰. Tributaries in the western, relatively pristine forested part of the watershed add predominantly NO-3 to the OMR with d15N-NO-3 indicative of soil nitrification. In contrast, tributaries in the eastern agriculturally-urban-industrially-used part of the basin contribute NO-3 with d15N-NO-3 values of about +16‰ indicative of manure and/or sewage derived NO-3. This difference in d15N-NO-3 values of tributaries was found to be independent of the season, but rather indicates a spatial change in the NO-3 source, which correlates with land use changes within the OMR basin. As a consequence of tributary influx, d15N-NO-3 values in the Oldman River increased from +6‰ in the downstream direction (W to E), although [NO-3 -N] increased only moderately (generally