Sourcing fatty acids to juvenile polar cod (Boreogadus saida) in the Beaufort Sea using compound-specific stable carbon isotope analyses

Juvenile polar cod (Boreogadus saida) are often found in close association with sea ice and represent an important trophic link in the Arctic food web. However, the proportional contribution of sea ice algal production via the sympagic food web to the diet of polar cod is unknown. To estimate the proportional contribution of fatty acids (FAs) from sea ice-derived particulate organic matter (i-POM) to the diet of juvenile polar cod, we used FA profiling and compound-specific stable carbon isotope analysis of individual FAs from juvenile polar cod collected from three regions in the Beaufort Sea. The δ¹³C values of the FAs 14:0, 16:4n-1, 18:0, 20:5n-3 and 22:6n-3 in the polar cod were found to most strongly resemble pelagic POM rather than i-POM. Results from isotope-mixing models using diatom FA markers indicated that the proportional contribution of FAs from i-POM to juvenile polar cod was ≤2 %, which suggests that juvenile polar cod had not sourced their FAs from i-POM. Thus, changes in sea ice coverage due to environmental change may not affect juvenile polar cod in regard to nutrients such as FAs but may still affect their populations by reducing critical shelter from predators.     

Signals of Climate Change in Butterfly Communities in a Mediterranean Protected Area

The European protected-area network will cease to be efficient for biodiversity conservation, particularly in the Mediterranean region, if species are driven out of protected areas by climate warming. Yet, no empirical evidence of how climate change influences ecological communities in Mediterranean nature reserves really exists. Here, we examine long-term (1998–2011/2012) and short-term (2011–2012) changes in the butterfly fauna of Dadia National Park (Greece) by revisiting 21 and 18 transects in 2011 and 2012 respectively, that were initially surveyed in 1998. We evaluate the temperature trend for the study area for a 22-year-period (1990–2012) in which all three butterfly surveys are included. We also assess changes in community composition and species richness in butterfly communities using information on (a) species’ elevational distributions in Greece and (b) Community Temperature Index (calculated from the average temperature of species'' geographical ranges in Europe, weighted by species'' abundance per transect and year). Despite the protected status of Dadia NP and the subsequent stability of land use regimes, we found a marked change in butterfly community composition over a 13 year period, concomitant with an increase of annual average temperature of 0.95°C. Our analysis gave no evidence of significant year-to-year (2011–2012) variability in butterfly community composition, suggesting that the community composition change we recorded is likely the consequence of long-term environmental change, such as climate warming. We observe an increased abundance of low-elevation species whereas species mainly occurring at higher elevations in the region declined. The Community Temperature Index was found to increase in all habitats except agricultural areas. If equivalent changes occur in other protected areas and taxonomic groups across Mediterranean Europe, new conservation options and approaches for increasing species’ resilience may have to be devised.     

Butterfly and grasshopper diversity patterns in humid Mediterranean grasslands: the roles of disturbance and environmental factors

The present paper studies butterfly, grasshopper and vascular plant communities in ten seasonally flooded grasslands with different anthropogenic disturbance regimes (NW Greece). Disturbance intensity was assessed on the basis of disturbance frequency and type (grazing, mowing, trampling, constructions). The distribution patterns of butterflies are regulated by humidity and elevation (Redundancy Analysis). Elevation, flower-heads abundance, low disturbance intensity and plant species richness predict grasshopper species richness well, while the latter together with humidity predict plant species richness (Generalized Linear Models). Chorthippus lacustris, a critically endangered endemic grasshopper species, is positively associated with humid microhabitats with high flower-heads abundance. An indicator value procedure reveals four butterfly species as being typical species for habitats with a pronounced character of hedgerows and tree lines. Conservation management of grassland butterflies should focus on the maintenance of the humid character of the humid grasslands as well as on the maintenance of hedgerows and tree lines. The reduction of human-induced disturbance towards occasional grazing and mowing seems to benefit both butterfly and grasshopper communities. Finally, we suggest the use of grasshoppers as surrogates for vascular plants and vice versa, given their congruent species richness patterns.     

Towards the co‐ordination of terrestrial ecosystem protocols across European research infrastructures

The study of ecosystem processes over multiple scales of space and time is often best achieved using comparable data from multiple sites. Yet, long‐term ecological observatories have often developed their own data collection protocols. Here, we address this problem by proposing a set of ecological protocols suitable for widespread adoption by the ecological community. Scientists from the European ecological research community prioritized terrestrial ecosystem parameters that could benefit from a more consistent approach to data collection within the resources available at most long‐term ecological observatories. Parameters for which standard methods are in widespread use, or for which methods are evolving rapidly, were not selected. Protocols were developed by domain experts, building on existing methods where possible, and refined through a process of field testing and training. They address above‐ground plant biomass; decomposition; land use and management; leaf area index; soil mesofaunal diversity; soil C and N stocks, and greenhouse gas emissions from soils. These complement existing methods to provide a complete assessment of ecological integrity. These protocols offer integrated approaches to ecological data collection that are low cost and are starting to be used across the European Long Term Ecological Research community.     

How are arthopod communities structured and why are they so diverse? Answers from Mediterranean mountains using hierarchical additive partitioning

Mountains are complex ecosystems supporting a great variety of taxa. Here, we explored the diversity patterns of arthropods in two mountains, pinpointing the spatial scale that accounts most for overall diversity variation, using an additive partitioning framework. Butterflies and Orthoptera were sampled in Rodopi (2012) and Grammos (2013) mountains. Diversity was partitioned into five hierarchical levels (mountain, elevational zone, habitat, transect and plot). We compared the estimated diversity values for each level to the respective permuted values expected by chance, for all species, as well as for species identified as “rare” or “common”. At broader spatial levels, the variation in total diversity was attributed to the beta diversity component: mountains accounted for 20.94 and 26.25% of butterfly and Orthoptera diversity, and elevational zones accounted for 28.94 and 35.87% respectively. At finer spatial scales, beta diversity was higher than expected by chance in terms of the Shannon index. The type of habitat was found to play a significant role only for rare orthopterans. Finally, common species were recognized for shaping overall species diversity. We highlight the importance of the spatial levels of elevation zone and then mountain position in conservation planning, due to the greater beta diversity recorded at this scale as compared to habitat or more finite scales. Monitoring programs might need to adapt different strategies with respect to the focal organisms, and consider patterns of common rather than rare species that found to drive the patterns of the entire community.     

The interaction between bird predation and plant cover in determining habitat occupancy of darkling beetles

Tenebrionid beetles in the Negev Desert exhibit size-related habitat segregation, with larger species found in denser cover. Size-dependent predation by birds has been suggested as the mechanism behind this habitat segregation. Two predictions of this hypothesis were tested: (1) plant cover reduces the predation efficiency of birds upon large tenebrionids, and (2) birds prefer larger species. Both predictions were supported: plant cover reduced predation rate by the most common spring and summer predatory birds: white storks ( Ciconia ciconia ) and stone curlews ( Burhinus oedicnemus ), in cage experiments. Results from preference experiments suggest that tenebrionid species can be divided according to their profitability as prey. Large species are the most profitable, medium-sized species are less profitable but still acceptable and small species are unprofitable and therefore ignored. Field observations demonstrated that the well-vegetated wadi habitats are dominated by large and small species whereas acceptable , medium-sized species are under-represented in this habitat. The results of the cage experiments indicate possible apparent competition between the large profitable and the medium acceptable tenebrionid species in the wadis. Aggregative response of predators in the profitable habitat is suggested as the mechanism leading to truncated distribution of prey species. Large profitable species are refuge-dependent, medium-sized acceptable species use enemy free space and small species are predator independent.     

Woodland strawberry axillary bud fate is dictated by a crosstalk of environmental and endogenous factors

Plant architecture is defined by fates and positions of meristematic tissues and has direct consequences on yield potential and environmental adaptation of the plant. In strawberries (Fragaria vesca L. and F. × ananassa Duch.), shoot apical meristems can remain vegetative or differentiate into a terminal inflorescence meristem. Strawberry axillary buds (AXBs) are located in leaf axils and can either remain dormant or follow one of the two possible developmental fates. AXBs can either develop into stolons needed for clonal reproduction or into branch crowns (BCs) that can bear their own terminal inflorescences under favorable conditions. Although AXB fate has direct consequences on yield potential and vegetative propagation of strawberries, the regulation of AXB fate has so far remained obscure. We subjected a number of woodland strawberry (F. vesca L.) natural accessions and transgenic genotypes to different environmental conditions and growth regulator treatments to demonstrate that strawberry AXB fate is regulated either by environmental or endogenous factors, depending on the AXB position on the plant. We confirm that the F. vesca GIBBERELLIN20-oxidase4 (FvGA20ox4) gene is indispensable for stolon development and under tight environmental regulation. Moreover, our data show that apical dominance inhibits the outgrowth of the youngest AXB as BCs, although the effect of apical dominance can be overrun by the activity of FvGA20ox4. Finally, we demonstrate that the FvGA20ox4 is photoperiodically regulated via FvSOC1 (F. vesca SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1) at 18°C, but at higher temperature of 22°C an unidentified FvSOC1-independent pathway promotes stolon development.

Environmental conditions and apical dominance dictate woodland strawberry plant architecture by regulating axillary bud fate.     

Stimulation of Photophosphorylation by Ascorbate as a Function of Light Intensity

When isolated, stroma-free thylakoids are illuminated in the presence of ADP and orthophosphate in the absence of any electron acceptor except O2, the addition of ascorbate stimulates electron transport through the formation of the radical monodehydroascorbate and the coupled synthesis of ATP (G. Forti and G. Elli [1995] Plant Physiol 109: 1207-1211). The stimulation is shown here to be higher at low light intensity. These observations are explained in terms of the increase of the electron transport rate by ascorbate, which established a higher value of the steady-state pH gradient, causing activation of ATP synthase, which is known to be dependent on the level of the H+-electrochemical potential difference, and a higher rate of proton flux across the membranes available for utilization by ATP synthesis.     

Mammalian genes expressed in Drosophila: a transgenic model for the study of mechanisms of chemical mutagenesis and metabolism.

Mammalian cytochrome P450s provide our first line of defence against the toxic effects of environmental chemicals. Ironically these enzymes also convert some compounds to their ultimate toxic or mutagenic species. Our knowledge of these mammalian enzymes and the role they play in chemical toxicity and mutagenesis has stemmed mostly from in vitro studies. In order to establish the role of specific enzymes in the toxicological response in vivo we have generated transgenic Drosophila which express mammalian cytochrome CYP2B1, which is a member of a large gene family encoding several important drug metabolising enzymes. The gene was fused to a Drosophila promoter which confers expression in the larval fat body. Using the Somatic Mutation And Recombination Test (SMART) we have demonstrated that transgenic larvae expressing the P450 are hypersensitive to the anticancer drug cyclophosphamide, a procarcinogenic substrate which is activated by the enzyme. This work demonstrates the potential of such transgenic Drosophila strains as an in vivo model for studying the role of specific mammalian drug metabolising enzymes in the pathways and metabolic cascades associated with the action of cytotoxic and carcinogenic chemicals, and also the chemical properties of specific classes of mutagen to be determined.