Trophic relationships at intrannual spatial and temporal scales of macro and megafauna around a submarine canyon off the Catalonian coast (western Mediterranean)

The spatial and temporal changes of near-bottom macrofauna (suprabenthos and macroplankton) and the trophic relationships of megabenthic decapod crustaceans were analyzed off the Catalonian coasts (western Mediterranean) around Berenguera submarine canyon in four periods (April and December 1991, March and July 1992) and four zones (within Berenguera Canyon at ca. 450 m, and on adjacent slope at ca. 400, 600 m and 1200 m). In March 1992, we found the highest macrofauna abundance and the smallest sizes in the canyon, suggesting a positive effect of river discharges on suprabenthos recruitment. By contrast, macroplankton (decapods, fishes and euphausiids) did not show higher recruitment into canyons. After analyzing the diet of 23 decapod crustaceans, we found a significant segregation between guilds feeding on zooplankton and on benthos. Zooplankton (euphausiids and Pasiphaeidae) and infauna (polychaetes, Calocaris macandreae and ophiuoroids) were consistently the main prey exploited by decapod crustaceans around Berenguera Canyon. We also found some macrophyte (Posidonia oceanica) consumption, which was higher in periods of water column homogeneity (winter–spring and late autumn). Positive correlations between decapods' gut fullness (F) and decapod abundance indicate feeding aggregations, while positive correlations were also found between F and Llobregat River (situated ca. 18 km from Berenguera head) flow 1 to 2 months before sampling. Increases in F were delayed only 1 month when zooplankton feeders were analyzed alone, while benthos feeders did not show significant relationships with any environmental variables. That indicates that the response of megabenthic decapods feeding on benthos to environmental shifts is slower than that of zooplankton feeders. The importance of river flows in enhancing food supply of macro- and megabenthos dwelling close to submarine canyons was apparent, with a delay in the fauna response of 0–2 months after river flow peaks.     

Modelling the physical and chemical changes in roofing slate caused by weathering processes

This research identifies the changes which takes place in roofing slate due to natural exposure and tries to replicate these changes experimentally. Traditional methods of testing, used by the British and other national standards, concentrate on the properties of unweathered samples and give no information on the relative durability of the different slates. Instead of concentrating on the initial properties, this research focuses on changes in the properties in order to assess durability. The effects of natural weathering were assessed by comparing old, used slates with new slates from the same or a similar source. The new slates were then weathered experimentally by repeated cycles of wetting and drying, and the increase in water absorbency compared with that observed in naturally weathering. Mineralogical differences due to both natural and experimental weathering were also measured using X-ray diffraction analysis. It was found that the effects of experimental weathering, using repeated cycles of wetting and drying, are similar to those observed in natural weathering. These include increased water absorbency and loss of crystallinity of the principal minerals. The greatest changes are found in those slates which are the most vulnerable to weathering, making it possible to identify poor quality slates.     

Mineral magnetic properties of mixtures of environmental and synthetic materials: linear additivity and interaction effects

Mineral magnetic properties have been used recently to classify and to attempt to quantify the sources of sediments through environmental systems. Linear modelling techniques could be used with a wide range of concentration-dependent magnetic measurements to quantify the sources of sediments. To investigate wider application of linear modelling techniques using mineral magnetic properties, research has been conducted using laboratory mixtures of up to six source materials, including both natural environmental materials and synthetic compounds. While six sources may seem ambitious, this figure was used as an absolute upper limit rather than giving a real prospect of mathematically unmixing six sources. It has been found that even with the most magnetically differentiable materials, large errors are encountered when modelling the sources of the mixtures. This paper investigates the causes of 'non-additivity' of certain magnetic measurements and the failure of the linear modelling of the sources of the mixtures. Possible reasons for this failure include source homogeneity, calibration and linearity of equipment, magnetic viscosity of materials and/or the changing physical characteristics of the source materials once mixed together (interaction effects). In testing linear additivity, low-frequency susceptibility is the most reliable mineral magnetic measurement, while remanence measurements suffer from a systematic error in the expected results. Results have shown that in the best controlled conditions where the sources are identified and are artificially mixed together, the results of linear modelling are quite poor and at best four sources can be 'unmixed' with reasonable success. It is suggested that interaction within the mixtures, especially when containing highly ferrimagnetic burnt environmental materials, causes some of the non-additivity phenomena.     

Using embodied HANPP to analyze teleconnections in the global land system: Conceptual considerations

Geografisk Tidsskrift—Danish Journal of Geography 109(2):119–130, 2009

In our rapidly globalizing world economy activities in one region have increasingly important effects on ecological, economic or social processes elsewhere, an effect which we here denote as ‘teleconnections’ between different regions. Biomass trade, one of the causes behind such teleconnections, is currently growing exponentially. Integrated analyses of changes in the global land system are high on the agenda of sustainability science, but a methodological framework for a consistent allocation of environmental burdens related to the consumption and production of biomass between regions has not been put forth to date. The concept of the ‘embodied human appropriation of net primary production’ (abbreviated ‘embodied HANPP’ or ‘eHANPP’) allows for the assessment of the ‘upstream’ effects on ecosystem energetics associated with a particular level of biomass consumption or with a given biomass-based product. This concept is based on HANPP and its two components: (1) productivity changes resulting from land conversion (ΔNPP_LC), and (2) harvest of biomass in ecosystems (NPP_h). HANPP, defined as the sum of ΔANPP_LC and NPP_h in any given territory, is indicative of the intensity with which humans use the land for their purposes. eHANPP is defined as the NPP appropriated in the course of biomass production, encompassing losses along the production chain as well as productivity changes induced through land conversion or harvest. By making the pressure exerted on ecosystems associated with imports and exports visible, eHANPP allows for the analysis of teleconnections between producing and consuming regions. This article puts forward the eHANPP concept, illustrates its utility for integrated socioecological land-change research based on top-down data on global HANPP and biomass consumption, and discusses the possibilities and challenges related to its quantification in bottom-up approaches.     

Release of volatile mercury from soils and non-vascular plants

Vegetation plays a significant role in the biogeochemical cycling of mercury. This conclusion is drawn from data presented here on bioaccumulation and subsequent release of volatile mercury from non-vascular plants together with the results of previous work. There is no obvious relation between total plant Hg or soil Hg and rate of release from the plant. Heat of vaporization for Hg⁰ was calculated at 13.99 kcal/g-atom; from soil it was experimentally determined at 13.81 kcal/g-atom but from the most active vascular plant was only 9.49 kcal/g-atom.     

Dynamics of suprabenthos off the Ebro Delta (Catalan Sea: western Mediterranean): Spatial 13 and temporal patterns and relationships with environmental factors

Dynamics of suprabenthos (hyperbenthos) composition and biomass have been simultaneously analyzed at two sites (S1, S2) off the Ebro River Delta (western Mediterranean). The stations, separated by ca. 5 km, differed in terms of depth (S1, 47 m; S2, 61 m), distance to the river mouth (S2 south of S1 and farther from the mouth) and fishing activity (S1 is a fishing ground; S2 is in an area closed to fishing). Peracarids (gammaridean amphipods, mysids, and cumaceans) were dominant among suprabenthic taxa. Seasonality was the main explanation for changes in taxonomic composition, with two seasonal groups indicated by MDS analyses (late summer–autumn, August–September, and November 2003; early summer, June and July samples). Peracarids at both S1 and S2 showed a peak of abundance in early July, with the highest densities reaching 5400 individuals (100 m)⁻² at S2. There was a sharp decrease of density in late July (S1) and August (S2), then an increase in August (S1) and in September (S2), respectively. A secondary peak of abundance occurred in November (S1) and December (S2). There was, therefore, a similar picture in the dynamics of suprabenthic peracarids at both sites, though with a delay of 1 month at the deeper S2. This pattern coincided with changes in river discharge (specifically, a decrease of suprabenthos when influx was below 200 m³ s⁻¹ in the period June–September 2003), and with the formation of a thermal gradient (also in June–September 2003) between S1 and S2 associated with the 15 °C isotherm. In addition, the decrease of suprabenthos in late July–August also coincided with the massive occurrence of mucilaginous aggregates close to the bottom (at between 0 and 4 m above the bottom), in the usual habitat of suprabenthos. C/N ratios in sediments (an indicator of the degree of degradation of organic matter (OM)) increased during this peak abundance of mucilaginous aggregates. The impoverishment of sediments in total organic carbon (TOC) was parallel to the decline of suprabenthos in late July–August, which is consistent with negative or non-significant correlations (evidenced both by Spearman's r and multi-regression models) between suprabenthos densities and TOC. Zooplankton taxa (e.g., copepods, chaetognaths, and fish/crustacean larvae living in the entire water column) showed significant correlations with a number of environmental factors (basically temperature), in contrast to suprabenthos. In conclusion, suprabenthos abundance was influenced by a number of natural factors, both intra-annual (e.g., OM quality, river discharges) and inter-annual (e.g., accumulation of mucilaginous remains). Probably due to their swimming capability, suprabenthos were not influenced by trawling activity. Considering the high P/B exhibited by suprabenthic crustaceans in comparison to infauna, this compartment likely has an important role in regulating food webs in those communities submitted to high fishing impact.     

Habitat preferences and life history of the red scorpion fish, Scorpaena notata, in the Mediterranean

Scorpaena notata is a small, sedentary scorpaenid species widely distributed in the Mediterranean and adjacent waters of the Atlantic. In the western Mediterranean it inhabits coastal continental shelf bottoms. In the Balearic Islands, these bottoms are characterised by the presence of the facies with red algae, including both Peyssonnelia and mäerl beds. These beds enhance the structural complexity, biodiversity and secondary production of the soft bottoms. Due to the oceanographic conditions of the Islands, the facies with red algae are especially rich in terms of biomass and algal coverage, and are widespread distributed between 40 and 90 m depth, where trawlers exploiting the continental shelf operate. The present work studies the biology of S. notata and its relationship with habitat characteristics. Special attention is focused on the aspects related to fish condition and growth as a tool to assess the importance of the facies with red algae for fish.     

Towards integrated essential variables for sustainability

ABSTRACT

Measuring the achievement of a sustainable development requires the integration of various data sets and disciplines describing bio-physical and socio-economic conditions. These data allow characterizing any location on Earth, assessing the status of the environment at various scales (e.g. national, regional, global), understanding interactions between different systems (e.g. atmosphere, hydrosphere, biosphere, geosphere), and modeling future changes. The Group on Earth Observations (GEO) was established in 2005 in response to the need for coordinated, comprehensive, and sustained observations related to the state of the Earth. GEO’s global engagement priorities include supporting the UN 2030 Agenda for Sustainable Development, the Paris Agreement on Climate, and the Sendai Framework for Disaster Risk Reduction. A proposition is made for generalizing and integrating the concept of EVs across the Societal Benefit Areas of GEO and across the border between Socio-Economic and Earth systems EVs. The contributions of the European Union projects ConnectinGEO and GEOEssential in the evaluation of existing EV classes are introduced. Finally, the main aim of the 10 papers of the special issue is shortly presented and mapped according to the proposed typology of SBA-related EV classes.     

Rock surface millimetre‐scale roughness and weathering of supratidal Mallorcan carbonate coasts (Balearic Islands)

Quantitative data on rock surface millimetre‐scale roughness are presented concerning the splash and spray geomorphologic domains of two coastal profiles developed on Mediterranean carbonate rocks. Differences of the roughness characteristics are attributed to rock properties, weathering agents and bioerosion. In the splash zone, roughness is related to sparsely distributed patterns of bioerosion, salt weathering and wave attack. In the spray zone, smooth surfaces seem to be the response to the solution processes that predominate, exerting a more homogenous influence on rock surface evolution. Copyright © 2006 John Wiley & Sons, Ltd.     

Dioxin compounds in the deep-sea rose shrimp Aristeus antennatus (Risso, 1816) throughout the Mediterranean Sea

Polychlorodibenzo-p-dioxins (PCDDs) and polychlorodibenzofurans (PCDFs) are among the more toxic anthropogenic contaminants. They are fat-soluble and accumulate in animal tissues. Exposure to PCDD/Fs can cause several endocrine, reproductive and developmental problems in animals, including human beings. Several studies have demonstrated that fish and invertebrates living in association with sediments are exposed to and accumulate contaminants, but to date there have been no studies of PCDD/Fs contamination in deep-sea regions. Specimens of Aristeus antennatus (Risso, 1816) were collected from depths of 600–2500 m at different points in the Mediterranean Sea, from the western basin off the coast of Barcelona to the central basin off the Peloponnesian Peninsula, with otter trawl gear. Amounts of PCDD/Fs were measured in different animal tissues by high resolution gas chromatography coupled to high resolution mass spectrometry (HRGC–HRMS). This is the first study to report the presence of PCDD/Fs in deep-sea organisms dwelling at depths below 600 m. A. antennatus presented levels of PCDD/Fs of the same order of magnitude, or slightly higher, as those found in shallow-water species (Melicertus kerathurus) with respect to land-generated contamination. This highlights the widespread distribution of these pollutants and the potential threat posed to the biodiversity of fragile and vulnerable ecosystems such as the deep-sea. PCDD/F levels detected in the edible parts (muscle) of the commercial shrimp A. antennatus were clearly below the toxic limit value established by European legislation. Levels followed the trend muscle<ovary<hepatopancreas, according to the lipid content of the organs in question. The specific profile of toxic PCDD/F congeners in the studied Penaeid shrimp specimens was characterized mainly by octachlorodibenzo-p-dioxin (OCDD), 2,3,7,8-tetrachlorodibenzofuran (TCDF) and 2,3,4,7,8-pentachlorodibenzofuran (PeCDF) congeners. Moreover, non 2,3,7,8-substituted congeners bioaccumulated in this species, as observed in shallow-water crustaceans. PCDD/Fs were found in the shrimp A. antennatus throughout the Mediterranean Sea. Total PCDD/Fs burdens were higher in shrimps caught in the western Mediterranean than in those caught at eastern Mediterranean sites. There was a tendency for higher levels of PCDD/F contamination in samples obtained from deeper (2500 m) than from shallower sites (600 m).