The development of composite dispersal functions for estimating absolute pollen productivity in the Swiss Alps

Considering the complexity of real-world pollen dispersal, a single set of parameters may be inadequate to model pollen dispersal, especially as dispersal occurs on both local and regional scales. Here we combine more than one dispersal function into a composite dispersal function (CDF). The function incorporates multiple parameters and different modes of pollen transportation, and thus has the potential to better simulate the relationship between deposited pollen and the surrounding vegetation than would otherwise be possible. CDFs based on different dispersal functions and combinations of dispersal functions were evaluated using a pollen-trap dataset from the Swiss Alps. Absolute pollen productivity (APP) was estimated at 7,700 ± 2,000 grains cm⁻² year⁻¹ for Larix decidua, 13,500 ± 1,900 grains cm⁻² year⁻¹ for Picea abies and 95,600 ± 17,700 grains cm⁻² year⁻¹ for Pinus cembra (with 95% confidence level). The results are consistent with previous APP estimates made from the same dataset using different methods.     

Phenotypic plasticity for skeletal growth,density and calcification of <Emphasis Type="Italic">Porites lobata</Emphasis> in response to habitat type

A reciprocal transplant experiment (RTE) of the reef-building coral Porites lobata between shallow (1.5 m at low tide) back reef and forereef habitats on Ofu and Olosega Islands, American Samoa, resulted in phenotypic plasticity for skeletal characteristics. Transplants from each source population (back reef and forereef) had higher skeletal growth rates, lower bulk densities, and higher calcification rates on the back reef than on the forereef. Mean annual skeletal extension rates, mean bulk densities, and mean annual calcification rates of RTE groups were 2.6–9.8 mm year⁻¹, 1.41–1.44 g cm⁻³, and 0.37–1.39 g cm⁻² year⁻¹ on the back reef, and 1.2–4.2 mm year⁻¹, 1.49–1.53 g cm⁻³, and 0.19–0.63 g cm⁻² year⁻¹ on the forereef, respectively. Bulk densities were especially responsive to habitat type, with densities of transplants increasing on the high energy forereef, and decreasing on the low energy back reef. Skeletal growth and calcification rates were also influenced by source population, even though zooxanthella genotype of source colonies did not vary between sites, and there was a transplant site x source population interaction for upward linear extension. Genetic differentiation may explain the source population effects, or the experiment may have been too brief for phenotypic plasticity of all skeletal characteristics to be fully expressed. Phenotypic plasticity for skeletal characteristics likely enables P. lobata colonies to assume the most suitable shape and density for a wide range of coral reef habitats.     

Secondary production and diet of an invasive snail in freshwater wetlands: implications for resource utilization and competition

Invasive species can monopolize resources and thus dominate ecosystem production. In this study we estimated secondary production and diet of four populations of Pomacea canaliculata, a freshwater invasive snail, in wetlands (abandoned paddy, oxbow pond, drainage channel, and river meander) in monsoonal Hong Kong (lat. 22°N). Apple snail secondary production (ash-free dry mass [AFDM]) ranged from 165.9 to 233.3 g m⁻² year⁻¹, and varied between seasons. Production was lower during the cool dry northeast monsoon, when water temperatures might have limited growth, but fast growth and recruitment of multiple cohorts were possible throughout much (7–10 months) of the year and especially during the warm, wet southwest monsoon. The diet, as revealed by stomach-content analysis, consisted mainly of detritus and macrophytes, and was broadly consistent among habitats despite considerable variation in the composition and cover of aquatic plants. Apple snail annual production was >10 times greater than production estimates for other benthic macroinvertebrates in Hong Kong (range 0.004–15 g AFDM m⁻² year⁻¹, n = 29). Furthermore, annual production estimates for three apple snail populations (i.e. >230 g AFDM m⁻² year⁻¹) were greater than published estimates for any other freshwater snails (range 0.002–194 g AFDM m⁻² year⁻¹, n = 33), regardless of climatic regime or habitat type. High production by P. canaliculata in Hong Kong was attributable to the topical climate (annual mean ~24°C), permitting rapid growth and repeated reproduction, together with dietary flexibility including an ability to consume a range of macrophytes. If invasive P. canaliculata can monopolize food resources, its high productivity indicates potential for competition with other macroinvertebrate primary consumers. Manipulative experiments will be needed to quantify these impacts on biodiversity and ecosystem function in wetlands, combined with management strategies to prevent further range extension by P. canaliculata.     

Reproduction,population dynamics and production of <Emphasis Type="Italic">Nereis falsa</Emphasis> (Nereididae: Polychaeta) on the rocky coast of El Kala National Park,Algeria

The polychaete Nereis falsa Quatrefages, 1866 is present in the area of El Kala National Park on the East coast of Algeria. Field investigations were carried out from January to December 2007 to characterize the populations’ reproductive cycle, secondary production and dynamics. Reproduction followed the atokous type, and spawning occured from mid-June to the end of August/early September when sea temperature was highest (20–23°C). The diameter of mature oocytes was approximately 180 μm. Mean lifespan was estimated to about one year. In 2007, the mean density was 11.27 ind. m⁻² with a minimum of 7.83 ind. m⁻² in April and a maximum of 14.5 ind. m⁻² in February. The mean annual biomass was 1.36 g m⁻² (fresh weight) with a minimum of 0.86 g m⁻² in December and a maximum of 2.00 g m⁻² in June. The population consisted of two cohorts distinguishable from size frequency distributions. One cohort corresponded to the recruitment of 2006 and the other appeared during the study period in September 2007. The annual production of N. falsa was 1.45 g m⁻² year⁻¹, and the production/biomass ratio was 1.07 year⁻¹.     

Ethanol and xylitol production from glucose and xylose at high temperature by <Emphasis Type="Italic">Kluyveromyces</Emphasis> sp. IIPE453

A yeast strain Kluyveromyces sp. IIPE453 (MTCC 5314), isolated from soil samples collected from dumping sites of crushed sugarcane bagasse in Sugar Mill, showed growth and fermentation efficiency at high temperatures ranging from 45°C to 50°C. The yeast strain was able to use a wide range of substrates, such as glucose, xylose, mannose, galactose, arabinose, sucrose, and cellobiose, either for growth or fermentation to ethanol. The strain also showed xylitol production from xylose. In batch fermentation, the strain showed maximum ethanol concentration of 82 ± 0.5 g l⁻¹ (10.4% v/v) on initial glucose concentration of 200 g l⁻¹, and ethanol concentration of 1.75 ± 0.05 g l⁻¹ as well as xylitol concentration of 11.5 ± 0.4 g l⁻¹ on initial xylose concentration of 20 g l⁻¹ at 50°C. The strain was capable of simultaneously using glucose and xylose in a mixture of glucose concentration of 75 g l⁻¹ and xylose concentration of 25 g l⁻¹, achieving maximum ethanol concentration of 38 ± 0.5 g l⁻¹ and xylitol concentration of 14.5 ± 0.2 g l⁻¹ in batch fermentation. High stability of the strain was observed in a continuous fermentation by feeding the mixture of glucose concentration of 75 g l⁻¹ and xylose concentration of 25 g l⁻¹ by recycling the cells, achieving maximum ethanol concentration of 30.8 ± 6.2 g l⁻¹ and xylitol concentration of 7.35 ± 3.3 g l⁻¹ with ethanol productivity of 3.1 ± 0.6 g l⁻¹ h⁻¹ and xylitol productivity of 0.75 ± 0.35 g l⁻¹ h⁻¹, respectively.     

Fluxes of greenhouse gases from Andosols under coffee in monoculture or shaded by <Emphasis Type="Italic">Inga densiflora</Emphasis> in Costa Rica

The objective of this study was to evaluate the effect of N fertilization and the presence of N₂ fixing leguminous trees on soil fluxes of greenhouse gases. For a one year period, we measured soil fluxes of nitrous oxide (N₂O), carbon dioxide (CO₂) and methane (CH₄), related soil parameters (temperature, water-filled pore space, mineral nitrogen content, N mineralization potential) and litterfall in two highly fertilized (250 kg N ha⁻¹ year⁻¹) coffee cultivation: a monoculture (CM) and a culture shaded by the N₂ fixing legume species Inga densiflora (CIn). Nitrogen fertilizer addition significantly influenced N₂O emissions with 84% of the annual N₂O emitted during the post fertilization periods, and temporarily increased soil respiration and decreased CH₄ uptakes. The higher annual N₂O emissions from the shaded plantation (5.8 ± 0.3 kg N ha⁻¹ year⁻¹) when compared to that from the monoculture (4.3 ± 0.1 kg N ha⁻¹ year⁻¹) was related to the higher N input through litterfall (246 ± 16 kg N ha⁻¹ year⁻¹) and higher potential soil N mineralization rate (3.7 ± 0.2 mg N kg⁻¹ d.w. d⁻¹) in the shaded cultivation when compared to the monoculture (153 ± 6.8 kg N ha⁻¹ year⁻¹ and 2.2 ± 0.2 mg N kg⁻¹ d.w. d⁻¹). This confirms that the presence of N₂ fixing shade trees can increase N₂O emissions. Annual CO₂ and CH₄ fluxes of both systems were similar (8.4 ± 2.6 and 7.5 ± 2.3 t C-CO₂ ha⁻¹ year⁻¹, −1.1 ± 1.5 and 3.3 ± 1.1 kg C-CH₄ ha⁻¹ year⁻¹, respectively in the CIn and CM plantations) but, unexpectedly increased during the dry season.     

Pollen dispersal and deposition characteristics of Abies alba, Fagus sylvatica and Pinus sylvestris, Roztocze region (SE Poland)

Pinus sylvestris L., Abies alba Mill. and Fagus sylvatica L.—the significant forest forming tree species in Europe are important for palaeoecological interpretations based on the results of pollen analysis of fossil deposits. The potential pollen loading for Pinus sylvestris, Abies alba and Fagus sylvatica was modelled using simulated and actual vegetation maps, measured fall-speed values and pollen productivity estimates from the literature. The influx of fir pollen drops sharply with distance from the pollen source due to the high fall speed and moderate pollen productivity. The vast majority of Abies alba pollen is deposited within less than 50 m of the sampling site and a major proportion within 100 m. For beech the corresponding numbers would be 300 and 1,800 m, and for pine 1,000 and 4,500 m. The observed mean pollen accumulation rate (PAR) values for Pinus and Fagus were ca. 5,800 and 1,100 grains cm⁻² year⁻¹, respectively. In the case of Abies, the mean annual PAR for the whole region is ca. 700 grains cm⁻² year⁻¹. In SE Poland the regional signal is represented by PARs of Abies alba <200 grains cm⁻² year⁻¹ and of Fagus sylvatica <500 grains cm⁻² year⁻¹. The local presence/absence threshold values for Abies alba, Fagus sylvatica and Pinus sylvestris are >1,000 grains cm⁻² year⁻¹, >2,000 grains cm⁻² year⁻¹ and >3,500 grains cm⁻² year⁻¹ respectively.     

Soil particle accumulation in termite (Macrotermes bellicosus) mounds and the implications for soil particle dynamics in a tropical savanna Ultisol

This study investigated the influence of mound-building termites on soil particle dynamics on the land surface and in soil-forming processes by examining the amount of soil particles in mound structures of Macrotermes bellicosus in a highly weathered Ultisol of tropical savanna. Soil particle turnover via the mounds was estimated using particle stock data and soil turnover data from previous studies. A 4-ha study plot with six mounds of relatively uniform shape and size was investigated. Soil mass constituting the mounds was 6,166 ± 1,581 kg mound⁻¹ within which the mound wall and nest body accounted for 5,002 ± 1,289 and 1,164 ± 293 kg, respectively. The mound wall contained a significantly larger amount of clay (252 ± 9.97 g kg⁻¹) balanced with a lower sand content (676 ± 26.5 g kg⁻¹) than in the adjacent surface (Ap1) horizon, (46.4 ± 12.8 g clay kg⁻¹; 866 ± 83.2 g sand kg⁻¹); the nest body had much higher clay content (559 ± 51.0 g kg⁻¹) but less sand (285 ± 79.2 g kg⁻¹) than the mound wall. As a result, the mounds of M. bellicosus accumulated clay of 2,874 ± 781 kg ha⁻¹ (corresponding to 2.52% of clay stock in the Ap1 horizon) along with an estimated clay turnover rate of 169 kg ha⁻¹ year⁻¹. These findings suggest a positive feedback effect from termite mound-building activity on soil particle dynamics in tropical savanna ecosystems: M. bellicosus preferentially use subsoil material for mound construction, resulting in relocation of illuvial clay in the subsoil to the land surface where clay eluviation from the surface soil and its illuviation in the subsoil are major soil-forming processes.     

Litterfall dynamics in carbonate and deltaic mangrove ecosystems in the Gulf of Mexico

From 1996 to 2002, we measured litterfall, standing litter crop, and litter turnover rates in scrub, basin, fringe and riverine forests in two contrasting mangrove ecosystems: a carbonate-dominated system in the Southeastern Everglades and a terrigenous-dominated system in Laguna de Terminos (LT), Mexico. We hypothesized that litter dynamics is driven by latitude, geomorphology, hydrology, soil fertility and soil salinity stress. There were significant temporal patterns in LT with litterfall rates higher during the rainy season (2.4 g m⁻² day⁻¹) than during the dry season (1.8 g m⁻² day⁻¹). Total annual litterfall was significantly higher in the riverine forest (12.8 Mg ha⁻² year⁻¹) than in the fringe and basin forests (9.7 and 5.2 Mg ha⁻² year⁻¹, respectively). In Southeastern Everglades, total annual litterfall was also significantly higher during the rainy season than during the dry season. Spatially, the scrub forest had the lowest annual litterfall (2.5 Mg ha⁻² year⁻¹), while the fringe and basin had the highest (9.1 and 6.5 Mg ha⁻² year⁻¹, respectively). In LT, annual standing litter crop was 3.3 Mg ha⁻¹ in the fringe and 2.2 Mg ha⁻¹ in the basin. Litter turnover rates were significantly higher in the fringe mangrove forest (4.1 year⁻¹) relative to the basin forests (2.2 year⁻¹). At Southeastern Everglades there were significant differences in annual standing litter crop: 1.9, 3.3 and 4.5 Mg ha⁻¹ at scrub, basin and fringe mangrove sites, respectively. Furthermore, turnover rates were similar at both basin and fringe mangrove types (2.1 and 2.0 year⁻¹, respectively) but significantly higher than scrub mangrove forest (1.3 year⁻¹). These findings suggest that litter export is important in regulating litter turnover rates in frequently flooded riverine and fringe forests, while in infrequently flooded basin forests, in situ litter decomposition controls litter turnover rates.     

Historical changes (1905–2005) in external phosphorus loads to Loch Leven, Scotland, UK

This article reviews historical changes in the total phosphorus (TP) inputs to Loch Leven, Scotland, UK. Data derived from palaeolimnological records suggest that inputs in the early 1900s were about 6 t TP year⁻¹ (0.45 g TP m⁻² year⁻¹). By 1985, this had risen to about 20 t TP year⁻¹ (1.5 g TP m⁻² year⁻¹) due to increases in runoff from agricultural land and discharges from point sources. By the late 1970s, increased TP inputs were causing serious degradation of lake water quality. Most noticeably, there had been an increase in cyanobacterial blooms. A catchment management plan was implemented in the early 1990s. This resulted in a 60% reduction in the annual TP input between 1985 (20 t TP year⁻¹/1.5 g TP m⁻² year⁻¹) and 1995 (8 t TP year⁻¹/0.6 g TP m⁻² year⁻¹). The main reduction was associated with better control of point source discharges, but attempts were also made to reduce inputs from diffuse sources. The reduction in external TP loading to the lake led to a marked decline in TP retention by the lake each year.     

Diatom fluxes in a tropical,oligotrophic lake dominated by large-sized phytoplankton

Alchichica is a warm-monomictic, oligotrophic lake whose phytoplanktonic biomass is dominated by large size (average ca. 55 μm) diatoms. The fast sinking phytoplankton leads to silica, and other nutrient exportation out of the productive zone of the lake. The aim of the present study was to identify and measure the sedimentation fluxes of the diatom species and their temporal dynamics to better understand the magnitude of silica and carbon fluxes. Sediment-traps were exposed at three different depths and collected monthly. A total of 13 diatom species were observed in the traps. The maximum diatom flux was in February (304 × 10⁶ cells m⁻² day⁻¹) related to the winter diatom bloom. The diatom silica (DSi) fluxes varied from 2.2 to 2,997 mg m⁻² day⁻¹ and the diatom carbon (DC) fluxes from 1.2 to 2,918 mg m⁻² d⁻¹. Cyclotella alchichicana was the main contributor (>98%) to the total DSi and DC fluxes. The annual diatom (15 × 10⁹ cells m⁻² year⁻¹), DSi (147 g m⁻² year⁻¹) and DC (92 g m⁻² year⁻¹) fluxes are higher than in other aquatic ecosystems of similar or even higher trophic conditions. Our findings in Alchichica are indicative of the relevance of the phytoplankton type and size in understanding the role tropical and oligotrophic lakes play regarding silica and carbon fluxes. In addition, our results support previous findings suggesting that inland aquatic ecosystems are more important than formerly thought in processing carbon, and can, therefore, affect regional carbon balances.     

Continuous cultures of <Emphasis Type="Italic">Pseudomonas putida</Emphasis> mt-2 overcome catabolic function loss under real case operating conditions

The long-term performance and stability of Pseudomonas putida mt-2 cultures, a toluene-sensitive strain harboring the genes responsible for toluene biodegradation in the archetypal plasmid pWW0, was investigated in a chemostat bioreactor functioning under real case operating conditions. The process was operated at a dilution rate of 0.1 h⁻¹ under toluene loading rates of 259 ± 23 and 801 ± 78 g m⁻³ h⁻¹ (inlet toluene concentrations of 3.5 and 10.9 g m⁻³, respectively). Despite the deleterious effects of toluene and its degradation intermediates, the phenotype of this sensitive P. putida culture rapidly recovered from a 95% Tol⁻ population at day 4 to approx. 100% Tol⁺ cells from day 13 onward, sustaining elimination capacities of 232 ± 10 g m⁻³ h⁻¹ at 3.5 g Tol m⁻³ and 377 ± 13 g m⁻³ h⁻¹ at 10.9 g Tol m⁻³, which were comparable to those achieved by highly tolerant strains such as P. putida DOT T1E and P. putida F1 under identical experimental conditions. Only one type of Tol⁻ variant, harboring a TOL-like plasmid with a 38.5 kb deletion (containing the upper and meta operons for toluene biodegradation), was identified.     

Ocean acidification and calcifying reef organisms: a mesocosm investigation

A long-term (10 months) controlled experiment was conducted to test the impact of increased partial pressure of carbon dioxide (pCO₂) on common calcifying coral reef organisms. The experiment was conducted in replicate continuous flow coral reef mesocosms flushed with unfiltered sea water from Kaneohe Bay, Oahu, Hawaii. Mesocosms were located in full sunlight and experienced diurnal and seasonal fluctuations in temperature and sea water chemistry characteristic of the adjacent reef flat. Treatment mesocosms were manipulated to simulate an increase in pCO₂ to levels expected in this century [midday pCO₂ levels exceeding control mesocosms by 365 ± 130 μatm (mean ± sd)]. Acidification had a profound impact on the development and growth of crustose coralline algae (CCA) populations. During the experiment, CCA developed 25% cover in the control mesocosms and only 4% in the acidified mesocosms, representing an 86% relative reduction. Free-living associations of CCA known as rhodoliths living in the control mesocosms grew at a rate of 0.6 g buoyant weight year⁻¹ while those in the acidified experimental treatment decreased in weight at a rate of 0.9 g buoyant weight year⁻¹, representing a 250% difference. CCA play an important role in the growth and stabilization of carbonate reefs, so future changes of this magnitude could greatly impact coral reefs throughout the world. Coral calcification decreased between 15% and 20% under acidified conditions. Linear extension decreased by 14% under acidified conditions in one experiment. Larvae of the coral Pocillopora damicornis were able to recruit under the acidified conditions. In addition, there was no significant difference in production of gametes by the coral Montipora capitata after 6 months of exposure to the treatments.     

Growth and allocation by a keystone wetland plant, <Emphasis Type="Italic">Panicum hemitomon</Emphasis>, and implications for managing and rehabilitating coastal freshwater marshes,Louisiana, USA

This paper attempts to establish linkages between growth by a keystone wetland plant, Panicum hemitomon Schultes, and the independent and interactive effect of nutrient and hydrologic regime to inform management and rehabilitation of thick-mat floating marsh (TMFM). To do so a manipulative glasshouse experiment employing created TMFM similar to that under consideration for field trials and two levels each of N, P and hydrology was conducted. P. hemitomon grew vigorously under saturated (flooding level with the surface of the mat) when compared to inundated (+15 cm flooding) hydrologic conditions, and under enriched (50 g m⁻² year⁻¹) when compared to non-enriched (25 g m⁻² year⁻¹) N. Further, and as inferred from net CO₂ assimilation, shoot biomass and rhizome biomass and length, N-enriched conditions seemed to lessen inundation stress. For all variables the interaction between N and hydrology was non-significant and there was no observable effect of P. We were unable to infer root or mat buoyancy from root specific gravity measurements but it was evident at harvest that saturation or minimal flooding is required for vigorous root and rhizome growth. This study provides insight to the notion that decreased mat buoyancy (and increased flooding level) resulting from sediment deposition associated with Mississippi River diversions could adversely affect TMFM sustainability, but more clearly demonstrates the need to maintain saturated hydrologic conditions for achieving the type of root and rhizome growth we feel is required for TMFM rehabilitation.     

Effect of soybean oil on the production of mycelial biomass and pleuromutilin in the shake-flask culture of <Emphasis Type="Italic">Pleurotus mutilis</Emphasis>

Effect of soybean oil on mycelial biomass and pleuromutilin biosynthesis by Pleurotus mutilis-04 was investigated in shake flask culture. The maximum pleuromutilin production and mycelial biomass were 8.32 ± 0.02 g l⁻¹ and 49.10 ± 1.00 g l⁻¹ when 20 g l⁻¹ soybean oil was fed at 24 and 96 h respectively. A repeated fed-batch fermentation strategy with feeding 3 g l⁻¹ soybean oil from 96 to 144 h at 24 h intervals was developed successfully to maintain mycelial growth and provide abundant fatty acids for pleuromutilin biosynthesis. Compared with glucose as the sole carbon source, soybean oil was obviously beneficial for the production of pleuromutilin. The results suggested that manipulation of metabolic regulation by soybean oil was an effective way to enhance the production pleuromutilin.     

Extreme high lichen growth rates detected in recently deglaciated areas in Tierra del Fuego

The goals of this study were to accurately determine the annual growth rate of two key lichen species for lichenometric studies in Tierra del Fuego and to provide more information on recent glacial evolution in the southernmost mountain range of South America. The study site was located on recent moraines deposited in front of a terminus of Pia Glacier in the East Arm of Pia Bay, a fjord of the Beagle Channel. Lichenometric measurements were made of the maximum and minimum axes on the five largest thalli of Rhizocarpon geographicum and Placopsis perrugosa at selected localities in the recently deglaciated area. Average growth rates were estimated from dated surfaces to be 0.63 mm year⁻¹ for R. geographicum and of 9.0 mm year⁻¹ for P. perrugosa. However, maximum growth rate of individual thalli of P. perrugosa could be as high as about 20 mm year⁻¹ increase in diameter directly measured from comparison between pictures taken over a 2-year interval. Both species had an almost linear increase in diameter size with the age of the rock surfaces and the distance from the glacier. The rapid colonization and growth of the lichens is mirrored by the higher plants with ecesis for Nothofagus trees being estimated at 4 years and height growth elongation at 30 cm year⁻¹.     

Annual sediment respiration in estuarine sandy intertidal flats in the Seto Inland Sea, Japan

To quantify organic matter mineralization at estuarine intertidal flats, we measured in situ sediment respiration rates using an infrared gas analyzer in estuarine sandy intertidal flats located in the northwestern Seto Inland Sea, Japan. In situ sediment respiration rates showed spatial and seasonal variations, and the mean of the rates is 38.8 mg CO₂-C m⁻² h⁻¹ in summer. In situ sediment respiration rates changed significantly with sediment temperature at the study sites (r ² = 0.70, p < 0.05), although we did not detect any significant correlations between the rates and sediment characteristics. We prepared a model for estimating the annual sediment respiration based on the in situ sediment respiration rates and their temperature coefficient (Q ₁₀ = 1.8). The annual sediment respiration was estimated to be 92 g CO₂-C m⁻² year⁻¹. The total amount of organic carbon mineralization for the entire estuarine intertidal flats through sediment respiration (43 t C year⁻¹) is equivalent to approximately 25% of the annual organic carbon load supplied from the river basin of the estuary.     

Drought,warming and soil fertilization effects on leaf volatile terpene concentrations in <Emphasis Type="Italic">Pinus halepensis</Emphasis> and <Emphasis Type="Italic">Quercus ilex</Emphasis>

The changes in foliar concentrations of volatile terpenes in response to water stress, fertilization and temperature were analyzed in Pinus halepensis and Quercus ilex. The most abundant terpenes found in both species were α-pinene and Δ³-carene. β-Pinene and myrcene were also abundant in both species. P. halepensis concentrations were much greater than those of Q. ilex in agreement with the lack of storage in the latter species (15205.60 ± 1140.04 vs. 0.54 ± 0.08 μg g⁻¹ [d.m.]). The drought treatment (reduction to 1/3 of full watering) significantly increased the total terpene concentrations in both species (54% in P. halepensis and 119% in Q. ilex). The fertilization treatment (addition of either 250 kg N ha⁻¹ or 250 kg P ha⁻¹ or both) had no significant effects on terpene foliar concentrations. The terpene concentrations increased from 0.25 μg g⁻¹ [d.m.] at 30°C to 0.70 μg g⁻¹ [d.m.] at 40°C in Q. ilex (the non-storing species) and from 2,240 μg g⁻¹ [d.m.] at 30°C to 15,621 μg g⁻¹ [d.m.] at 40°C in P. halepensis (the storing species). Both species presented negative relationship between terpene concentrations and relative water contents (RWC). The results of this study show that higher terpene concentrations can be expected in the warmer and drier conditions predicted for the next decades in the Mediterranean region.     

Preparation of galactans from <Emphasis Type="Italic">Gracilaria debilis</Emphasis> and <Emphasis Type="Italic">Gracilaria salicornia</Emphasis> (Gracilariales,Rhodophyta) of Indian waters

Superior quality non-methylated and low-sulphated galactans were extracted from two Indian agarophytes namely Gracilaria debilis and G. salicornia growing naturally along the west coast of India, using an eco-friendly method developed in our laboratory. The galactans were characterised by FT-IR, ¹³C NMR, GC-MS, ICP, GPC and rheological measurements. G. debilis produced exclusively non-methylated galactan exhibiting the greatest gel strength of 650±25 g cm⁻² and lowest sulphate of 0.21±0.06%. On the contrary, G. salicornia polysaccharide was composed of non-methylated galactose (major) and mannose (minor), having gel strength of 510±25 g cm⁻² and sulphate of 0.45±0.06%. Very low heavy metal contents were determined in both the galactan samples, which may thus be potentially useful in food and biological applications.     

Drift-ice and under-ice water communities in the Gulf of Bothnia (Baltic Sea)

The algal, protozoan and metazoan communities within different drift-ice types (newly formed, pancake and rafted ice) and in under-ice water were studied in the Gulf of Bothnia in March 2006. In ice, diatoms together with unidentified flagellates dominated the algal biomass (226 ± 154 μg ww l⁻¹) and rotifers the metazoan and protozoan biomass (32 ± 25 μg ww l⁻¹). The under-ice water communities were dominated by flagellates and ciliates, which resulted in lower biomasses (97 ± 25 and 21 ± 14 μg ww l⁻¹, respectively). The under-ice water and newly formed ice separated from all other samples to their own cluster in hierarchical cluster analysis. The most important discriminating factors, according to discriminant analysis, were chlorophyll-a, phosphate and silicate. The under-ice water/newly formed ice cluster was characterized by high nutrient and low chlorophyll-a values, while the opposite held true for the ice cluster. Increasing trends in chlorophyll-a concentration and biomass were observed with increasing ice thickness. Within the thick ice columns (>40 cm), the highest chlorophyll-a concentrations (6.6–22.2 μg l⁻¹) were in the bottom layers indicating photoacclimation of the sympagic community. The ice algal biomass showed additional peaks in the centric diatom-dominated surface layers coinciding with the highest photosynthetic efficiencies [0.019–0.032 μg C (μg Chl-a ⁻¹ h⁻¹) (μE m⁻² s⁻¹)⁻¹] and maximum photosynthetic capacities [0.43-1.29 μg C (μg Chl-a ⁻¹ h⁻¹)]. Rafting and snow-ice formation, determined from thin sections and stable oxygen isotopic composition, strongly influenced the physical, chemical and biological properties of the ice. Snow-ice formation provided the surface layers with nutrients and possibly habitable space, which seemed to have favored centric diatoms in our study.