Diurnal and seasonal fluctuations in wood ant (Formica polyctena) nest temperature in two geographically distant populations along a south – north gradient

Temperature changes were recorded continuously in eleven nests of Formica polyctena located in Southern Finland and the Czech Republic. Nest temperatures were recorded in the Czech site from 2003 to 2005 and in Finland during 2004 – 2005. Seasonal changes in nest temperature were very similar in both locations. During summer, the ants maintained a relatively high and constant temperature in their nest in both locations. Summer nest temperatures in Finland were higher than those in Czech during 2004 –2005 but did not differ from those in Czech during 2003– 2004. This indicated that the geographical differences were less important than difference between seasons. Nest temperature peaked in June. During summer, daily temperature fluctuations were significantly lower in Finland than in Czechia probably due to shorter nights in Finland. Apparent differences in daily temperature patterns were found in nests with different moisture in both locations. In dry nests, temperature peaked in the evening and decreased overnight, whereas the apparent increase was delayed to the night in wet nests. The spring increase in temperature in wet nests was much steeper that that in the dry ones when whole spring period is considered. During one day, temperatures fluctuated much more in dry nests than in wet ones. These differences seem to be caused by differences in thermal capacity between dry and wet nests. Received 24 July 2006; revised 19 February 2007; accepted 19 May 2007.     

Effect of light and temperature on the cyanobacterium <Emphasis Type="Italic">Arthronema africanum</Emphasis> - a prospective phycobiliprotein-producing strain

The effect of light intensity (50–300 μmol photons m⁻² s⁻¹) and temperature (15–50°C) on chlorophyll a, carotenoid and phycobiliprotein content in Arthronema africanum biomass was studied. Maximum growth rate was measured at 300 μmol photons m⁻² s⁻¹ and 36°C after 96 h of cultivation. The chlorophyll a content increased along with the increase in light intensity and temperature and reached 2.4% of dry weight at 150 μmol photons m⁻² s⁻¹ and 36°C, but it decreased at higher temperatures. The level of carotenoids did not change significantly under temperature changes at illumination of 50 and 100 μmol photons m⁻² s⁻¹. Carotenoids were about 1% of the dry weight at higher light intensities: 150 and 300 μmol photons m⁻² s⁻¹. Arthronema africanum contained C-phycocyanin and allophycocyanin but no phycoerythrin. The total phycobiliprotein content was extremely high, more than 30% of the dry algal biomass, thus the cyanobacterium could be deemed an alternative producer of C-phycocyanin. A highest total of phycobiliproteins was reached at light intensity of 150 μmol photons m⁻² s⁻¹ and temperature of 36°C, C-phycocyanin and allophycocyanin amounting, respectively, to 23% and 12% of the dry algal biomass. Extremely low (<15°C) and high temperatures (>47°C) decreased phycobiliprotein content regardless of light intensity.     

Composition and Nutritional Characteristics of Fungi Consumed by Callimico goeldii in Pando, Bolivia

Though ≥22 species of Primates consume fungi, most do so at low rates, comprising <5% of their feeding time. Goeldi's monkeys (Callimico goeldii), spend up to 29% of their feeding time year-round consuming fungal sporocarps, the fruiting bodies of fungi. We provide comprehensive data on the nutritional characteristics of 4 species of fungi consumed by Callimico goeldii (Ascopolyporus polyporoides, Ascopolyporus polychrous, Auricularia auricula, and Auricularia delicata). The composition of the fungi is similar to that of other fungi: predominantly fiber (66.2–83.0% dry matter) with small amounts of sugar (2.0–5.6% dry matter) and crude fat (0.9–1.6% dry matter). Though the crude protein content is substantial (5.5–13.4% dry matter), much of the nitrogen in the fungi is not likely to be available to Callimico goeldii because it is associated with indigestible food components or is in nonprotein form. The mineral content of the fungi are within the normal range for fungi generally and the calcium-to-phosphorus ratio is low (0.07–0.25). Fungi appear to be a low-quality food resource for Callimico goeldii and may contribute to their relatively large home ranges and low population density compared to other Callitrichinae. Research on the ability of Callimico goeldii to digest fungi is needed to understand fully the nutritional value of fungi to them. We discuss adaptations Callimico goeldii may have for improving their ability to obtain nutrients from fungi and potential ecological correlates of mycophagy.     

In vitro production of microtubers for conservation of potato germplasm: Effect of genotype,abscisic acid,and sucrose

Summary With the objective of using microtubers for conservation of potato germplasm, the main effects of genotype, abscisic acid (ABA), and sucrose level, and of their interactions on biomass production, microtuberization, microtuber dormancy, and dry matter content, were studied. ABA decreased both microtuber production and microtuber dormancy, whereas higher concentrations (60–80 gl⁻¹) of sucrose promoted biomass production, microtuber production as well as microtuber dry matter content. Microtubers stored under diffused light had longer dormancy than those kept continuously in the dark. Interactions among various factors conditioned the main effects for some characters. In vitro performance of the genotypes studied was related to their known performance under in vivo conditions for most of the characters. Microtubers produced on media devoid of ABA and containing high sucrose concentrations and N⁶-benzyladenine (44.38 μM) could be stored for 12 mo. under diffused light at 6±1°C.     

A novel dichloromethane-degrading <Emphasis Type="Italic">Lysinibacillus sphaericus</Emphasis> strain wh22 and its degradative plasmid

Dichloromethane (DCM)-degrading bacterium strain wh22 (GenBank accession number FJ418643) was isolated and identified as Lysinibacillus sphaericus based on standard morphological and physiological properties, cellular fatty acid composition, mole percent guanine–cytosine content, and nucleotide sequence analysis of enzymatically amplified 16S ribosomal deoxyribonucleic acid. The strain also grew on many other halocarbons found in the waste gases of industrial effluents, such as 1,2-dichloroethane, chlorobromomethane, methylene bromide, 1,1,1-trichloroethane, trichloroethylene, and hexachlorobenzene. The strain harbored a novel degradative plasmid, pRC11 (48.8 kb). The genes coding for the metabolism of DCM were found to be plasmid-borne, and a physical map of the plasmid has been established. The purified plasmid was transformed to dcm ⁻ Escherichia coli DH5 at a rate of 1.65 × 10⁵. The transformed cells were able to grow on DCM at a concentration of 5–16 mM and can be further used as an excellent source for genetic manipulations leading to the construction of genetically modified microbial strains or genetically engineered microorganisms.     

Changes in biomass and nutrient content of <Emphasis Type="Italic">Nymphoides hydrophylla</Emphasis> (Lour.) O. Kuntz. in a tropical pond: a comparison with other tropical and temperate species

A study was conducted to ascertain monthly changes in biomass of the plant and nutrient content in various organs of Nymphoides hydrophylla grown in a tropical pond during September 1999–August 2000 in relation to environmental factors. Biomass of N. hydrophylla ranged from 25 to 247 g dry weight m⁻². Among the various organs, leaf blade showed highest nitrogen (3.0–4.6%) and phosphorus content (0.9–2.4%). Comparative data of three Nymphoides species showed that N. peltata, the temperate species, had maximum potential of biomass production while long flowering period, year around growth, higher nitrogen content in various organs and presence of other associated flora were unique features of tropical species (N. hydrophylla and N. indica). Both water temperature and water level together appeared to be the best environmental variables that significantly explained the variability in biomass of N. hydrophylla.     

Impacts of Argentine ants on avian nesting success

Biological invasions can have severe and widespread impacts on ecological communities. A few species of ants have become particularly damaging invaders but quantitative data of their impacts on many taxa is still lacking. We provide experimental evidence using artificial nests baited with quail eggs that the invasive Argentine ant (Linepithema humile) can be a significant avian nest predator – Argentine ants recruited to more nests and in higher abundance than the native ant species they displace. However, at a site invaded by Argentine ants, we monitored over 400 nests of a ground-nesting species, the Dark-eyed Junco (Junco hyemalis), and found that less than 2% of nests failed as a result of Argentine ant predation/infestation. A review of the literature also suggests that Argentine ants may not be a serious threat to bird nests relative to other predators or parasites. However, invasive ants with the capability of overwhelming prey though stinging (specifically the red-imported fire ant, Solenopsis invicta), may have a higher impact on avian nesting success. Received 14 January 2005; revised 28 April 2005; accepted 12 May 2005.     

Effects of herbicide chlorsulfuron on growth and nutrient uptake parameters of wheat genotypes differing in Zn-efficiency

Prunings of Calliandra calothyrsus, Grevillea robusta, Leucaena diversifolia and farm yard manure were applied each cropping season at 3 and 6 t dry matter ha⁻¹ to an Oxisol in Burundi. The field plots also received basal applications of nitrogen (N), phosphorus (P) and potassium (K). Application of the tree prunings or farm yard manure decreased the concentration of monomeric inorganic aluminium (Al) in soil solution from 2.92 mg Al dm⁻³ in the control plots to 0.75 mg Al dm⁻³ in the plots receiving 6 t ha⁻¹ Calliandra prunings. The other organic materials also decreased the concentration of monomeric inorganic aluminium in the soil solution. The lowered Al concentration led to a corresponding decrease in the percentage Al saturation of the 0–10 cm soil layer from 80% to 68%. Grain yields of maize and beans were strongly inversely related to the percentage Al saturation of the soil. This confirms that soil acidity was the main constraint to maize and beans production. The yield improvement was mainly attributed to the ameliorating effects of the organic matter application on Al toxicity. The nutrient content had less effect presumably because of fertilizer use. In the best treatments, the yield of maize increased from 0.9 to 2.2 t ha⁻¹ and the corresponding beans yield increased from 0.2 to 1.2 t ha⁻¹. A C Borstlap Section editor     

Plant and Soil N Response of Southern Californian Semi-arid Shrublands After 1 Year of Experimental N Deposition

Large inputs of atmospheric N from dry deposition accumulate on vegetation and soil surfaces of southern Californian chaparral and coastal sage scrub (CSS) ecosystems during the late-summer and early-fall and become available as a pulse following winter rainfall; however, the fate of this dry season atmospheric N addition is unknown. To assess the potential for dry season atmospheric N inputs to be incorporated into soil and/or vegetation N pools, an in situ N addition experiment was initiated in a post-fire chaparral and a mature CSS stand where 10 × 10 m plots were exposed to either ambient N deposition (control) or ambient +50 kg N ha⁻¹ (added N) added as NH₄NO₃ during a single application in October 2003. After 1 year of N addition, plots exposed to added N had significantly higher accumulation of extractable inorganic N (NH₄−N + NO₃−N) on ion exchange resins deployed in the 0–10 cm mineral soil layer and higher soil extractable N in the subsurface (30–40 cm) mineral soil than plots exposed to ambient N. Chaparral and CSS shrubs exposed to added N also exhibited a significant increase in tissue N concentration and a decline in the tissue C:N ratio, and added N significantly altered the shrub tissue δ ¹⁵N natural abundance. Leaching of inorganic N to 1 m below the soil surface was on average 2–3 times higher in the added N plots, but large within treatment variability cause these differences to be statistically insignificant. Although a large fraction of the added N could not be accounted for in the shrub and soil N pools investigated, these observations suggest that dry season N inputs can significantly and rapidly alter N availability and shrub tissue chemistry in Mediterranean-type chaparral and CSS shrublands of southern California.     

The influence of summertime fog and overcast clouds on the growth of a coastal Californian pine: a tree-ring study

The coast of California is home to numerous rare, endemic conifers and other plants that are limited in distribution by drought sensitivity and the summer-dry climate that prevails across most of the state. Ecologists have long assumed that some coastal plant populations survived the early Pleistocene transition to a warmer and drier environment because they benefit from frequent fog and stratus clouds that provide water and shade during the rainless summer. One such population is that of Torrey pine (Pinus torreyana ssp. Insularis) on Santa Rosa Island in Channel Islands National Park. Here we report that the tree-ring width record from this population indicates strong growth sensitivities to summer fog drip and cloud shading. We quantified the effects of summer cloud cover by comparing ring-width indices to coastal airport cloud-frequency records (1944–2004). For the first time observed, summertime cloud frequency correlated positively with ring-width indices, regardless of whether the effect of rainfall was first removed from the ring-width record. The effect of ground-level fog was strongest in July early mornings (03:00 PST, R ² = 0.262, P < 0.0002). The effect of clouds high enough to provide shade but not fog water was also strongest in July, but climbed steadily throughout the day before becoming strongest in late afternoon (16:00–18:00 PST, R ² = 0.148, P < 0.004). Correlations were substantially stronger in years with higher soil moisture, suggesting that growth response to summer clouds is strongly affected by pre-summer rainfall. A change in the height and/or timing of coastal cloud formation with climate change would likely affect this and other populations of California’s coastal vegetation.     

Production ecology of phyto- and zooplankton in a eutrophic pond dominated byChaoborus flavicans (Diptera: Chaobolidae)

Primary production of phytoplankton and secondary production of a daphnid and a chaoborid were studied in a small eutrophic pond. The gross primary production of phytoplankton was 290 gC m⁻² per 9 months during April–December. Regression analysis showed that the gross primary production was related to the incident solar radiation and the chlorophylla concentration and not to either total phosphorus or total inorganic nitrogen concentration. The mean chlorophylla concentration (14.2 mg m⁻³), however, was about half the expected value upon phosphorus loading of this pond. The mean zooplankton biomass was 1.60 g dry weight m⁻², of whichDaphnia rosea and cyclopoid copepods amounted to 0.69 g dry weight m⁻² and 0.61 g dry weight m⁻², respectively. The production ofD. rosea was high during May–July and October and the level for the whole 9 months was 22.6 g dry weight m⁻².Chaoborus flavicans produced 10 complete and one incomplete cohorts per year. Two consecutive cohorts overlapped during the growing season. The maximum density, the mean biomass, and the production were 19,100 m⁻², 0.81 g dry weight m⁻², and 11.7 g dry weight m⁻²yr⁻¹, respectively. As no fish was present in this pond, the emerging biomass amounted to 69% of larval production. The production ofC. flavicans larvae was high in comparison with zooplankton production during August–September, when the larvae possibly fed not only on zooplankton but also algae.     

Effects of temperature and salinity on the growth of Gracilaria verrucosa and G. chorda, with the Potential for mariculture in Korea

Effects of temperature and salinity on the growth of the two agarophytes, Gracilaria verrucosa (Hudson) Papenfuss and Gracilaria chorda Holmes were examined in Korea. Both species grew over a wide range of temperatures (10–30 ^∘C) and salinities (5–35‰), and grew well at 17–30 ^∘C and a salinity of 15–30‰. In culture, G. verrucosa grew faster than G. chorda and their maximum growth rates were 4.95% day⁻¹ (30 ^∘C, 25‰) and 4.47% day⁻¹ (at 25 ^∘C, 25‰), respectively. In the field population the maximum growth and fertility of G. chorda were observed in summer. The growth rate of G. verrucosa was slightly higher than that of G. chorda for 2 weeks on the cultivation rope and in culture but it was much lower after being contaminated with epiphytes. The biomass of the epiphytes was 0.82 g dry wt. per host plant in G. verrucosa and 0.001 g in G. chorda. G. chorda exhibited resistance to epiphytism and grew 7 times in length and the dry weight increased 15 times after 55 days. In conclusion, G. chorda appears to be a good agarophyte with a fast growth rate and resistance to epiphytesm, and compared with G. verrucosa, has good potential for commercial cultivation.     

Soil moisture redistribution as a mechanism of facilitation in savanna tree–shrub clusters

Plant–soil water relations were examined in the context of a selective removal study conducted in tree–shrub communities occupying different but contiguous soil types (small discrete clusters on shallow, duplex soils versus larger, extensive groves on deep, sandy soils) in a subtropical savanna parkland. We (1) tested for the occurrence of soil moisture redistribution by hydraulic lift (HL), (2) determined the influence of edaphic factors on HL, and (3) evaluated the significance of HL for overstory tree–understory shrub interactions. Diel cycling and nocturnal increases in soil water potential (Ψ_soil), characteristic signatures of HL, occurred intermittently throughout an annual growth cycle in both communities over a range of moisture levels (Ψ_soil=−0.5 to −6.0 MPa) but only when soils were distinctly stratified with depth (dry surface/wet deep soil layers). The magnitude of mean (±SE) diel fluctuations in Ψ_soil (0.19±0.01 MPa) did not differ on the two community types, though HL occurred more frequently in groves (deep soils) than clusters (shallow soils). Selective removal of either Prosopis glandulosa overstory or mixed-species shrub understory reduced the frequency of HL, indicating that Prosopis and at least one other woody species was conducting HL. For Zanthoxylum fagara, a shallow-rooted understory shrub, Prosopis removal from clusters decreased leaf water potential (Ψ_leaf) and net CO₂ exchange (A) during periods of HL. In contrast, overstory removal had neutral to positive effects on more deeply-rooted shrub species (Berberis trifoliolata and Condalia hookeri). Removal of the shrub understory in groves increased A in the overstory Prosopis. Results indicate the following: (a) HL is common but temporally dynamic in these savanna tree–shrub communities; (b) edaphic factors influencing the degree of overstory/understory development, rooting patterns and soil moisture distribution influence HL; (c) net interactions between overstory and understory elements in these woody patches can be positive, negative and neutral over an annual cycle, and (d) Prosopis-mediated HL is an important mechanism of faciliation for some, but not all, understory shrubs.     

Abundance patterns of soil micro-arthropods at aPinus pumila scrub in an alpine range of central Japan

Seasonal changes in abundances of major soil micro-arthropods were assessed at aPinus pumila scrub in an alpine range of central Japan during a period with no snow coverage. The total abundance showed a peak in late August, reaching no less than 140 000 m⁻², which was comparable to that in an evergreen coniferous plantation in the cool-temperate zone. Collembola was the most dominant group of soil micro-arthropods, comprising about 50% of the total, followed by oribatid mites (Acari [O]) occupying 20%. Annual mean air temperature was no more than 2.1 °C and the daily fluctuation in temperature was less in soil layers. The thickness of the A₀ layer reached 9–10 cm and soil organic matter accumulation was estimated to be 45–58 ton dry weight ha⁻¹. The large amount of litterfall and organic matter accumulation in the soil, comparable to those of sub-alpine evergreen coniferous forests, and a lower decomposition rate due to severe environmental conditions, suggest the relative importance of litter processing by soil micro-arthropods such as Collembola and Acari, especially in alpine regions.     

How Ant Nests Increase Soil Biota Richness and Abundance: A Field Experiment

Although many studies have shown that ant nests tend to increase soil nutrient concentrations, only a few have examined ant impact on soil biota. To date, no one has examined the mechanism behind this complex ‘ant effect.’ In this study, we employed a 2 × 2 complete factorial design (water × food) in the field to mimic the effects of harvester ant nests (Messor andrei) on soil. We hypothesized that, in the absence of ants, addition of moisture and food (seeds and insects) would interact to produce conditions found in ant nests. Our results indicated that the addition of food to the soil (regardless of water addition) best mimicked the conditions found inside M. andrei nests. Both food-treated and ant-nest soils supported higher numbers of bacteria, nematodes, miscellaneous eukaryotes, and microarthropods compared to the other soil treatments. Microbial richness was also highest in ant and food-treated samples. Moreover, the ant effect in our experiment occurred in just two months. Because ants are a widespread, abundant group with many long-lived species, they could substantially influence soil properties and belowground food webs and may have important restoration/conservation implications for terrestrial communities.     

Root turnover in a beech and a spruce stand of the Belgian Ardennes

The theoretical basis of fine root turnover estimation in forest soils is discussed, in relation to appropriate experimental techniques of measurement. After sequential coring, the correct expression is the sum of significant positive increments of live and dead roots of the various diameter categories, to which the transfer of dead roots to organic matter derived from roots, OMDR, has to be added. This should not be confounded with dead root mineralization. The transfer rates should first be estimated in root dimensions and not in weight of dry matter. The measurements were carried out in a 120 year old beech (Fagus sylvatica L.) stand and a 35 year old Norway spruce (Picea abies Karst) stand, in the Eastern Ardennes, Belgium. The turnover rate of fine roots (diam. <5 mm) was 4393 kg ha⁻¹ year⁻¹ (root dry weight), including 711.2 kg ha⁻¹ year⁻¹ for dead root transfer to OMDR, for beech. For spruce, turnover rate was 7011 kg ha⁻¹ year⁻¹ (root dry weight), including 1498 kg ha⁻¹ year⁻¹ for dead root transfer to OMDR. Under beech, there was a slight root density increase in spring. No seasonal fluctuations were observed under spruce, but a strong irreversible drop in live root growth was found in the later season 1980–1981, corresponding to a decrease of tree height growth and trunk radius increment. Turnover rates were further expressed in dry weight and in amounts of elements (kg ha⁻¹ year⁻¹) (Ca, Mg, K, Na, Al, N, P, S). Correlative relations between root dimensions and dry weight and element concentrations show that the derived values, and in particular root specific density (dry weight volume⁻¹) vary according to species, root category, and seasonal sampling. Various schemes of seasonal variations of root growth, described in Europe, show that the major dependance on general climate is obscured by environmental factors (soil, exposure, species). It is suggested that root density fluctuation approach the steady state on an annual basis under mild Atlantic conditions.     

其它可利用食物对小花宽瓣黄堇(Corydalis giraldii Fedde)种子散布的影响

作为蚁播植物种子的重要传播者,蚂蚁不但取食种子上附着的油质体,也喜食其它富含蛋白质、脂类、糖和维生素等的食物,因此环境中其它可利用食物的存在可能会影响蚂蚁对种子的搬运进而影响种子散布,但目前对于这种影响是如何发生的仍不清楚。在野外研究了蚂蚁对小花宽瓣黄堇(Corydalis giraldii Fedde)种子、肉、蜂蜜、苹果、馒头等食物的趋性和偏好程度,以及添加食物后蚂蚁对种子的拜访频率和搬运效率,以揭示其它可利用食物如何影响蚂蚁觅食和取食偏好,进而影响小花宽瓣黄堇种子散布。结果显示,在所诱捕的8种蚂蚁中,玉米毛蚁(Lasius alienus(Foerster))和丝光蚁(Formica fusca Linnaeus)是小花宽瓣黄堇种子的主要搬运者,不同食物诱捕的玉米毛蚁数量无显著性差异(P0.05),但蜂蜜和苹果诱捕的丝光蚁数量均显著大于种子(P0.05)。玉米毛蚁和丝光蚁均为杂食性,在觅食中分别行使群体募集和简单协作性募集。在仅有种子的对照处理中,玉米毛蚁和丝光蚁对种子的拜访频率分别为(38.73±4.57)头和(30.8±2.87)头(40min,n=15),两种蚂蚁对种子的拜访频率差异不显著(P0.05);玉米毛蚁和丝光蚁搬运种子的效率分别为(33.87±4.22)粒和(16.27±3.35)粒(40min,n=15),玉米毛蚁的搬运效率显著高于丝光蚁(P0.05)。与对照相比,添加馒头、苹果和蜂蜜后丝光蚁对种子的拜访频率显著降低(P0.05),分别为(15.6±3.61)头、(9.07±1.4)头和(7.67±1.58)头(40min,n=15);添加苹果和蜂蜜后丝光蚁对种子的搬运效率显著降低(P0.05),分别为(3.47±1.17)粒和(2.87±0.9)粒(40min,n=15);添加不同食物后玉米毛蚁对种子的拜访频率和搬运效率均无显著变化(P0.05)。研究结果表明行使群体募集的玉米毛蚁比行使简单协作募集的丝光蚁有更高的种子搬运效率,添加食物后影响丝光蚁对种子的拜访频率和搬运效率,这说明其它可利用食物对小花宽瓣黄堇种子散布的影响与搬运蚂蚁的种类及其觅食的募集方式有关。研究结果可为进一步研究蚂蚁与植物(种子)间的互利共生关系及其影响因素提供资料。     

Population Biology of Maculinea rebeli (Lepidoptera: Lycaenidae) on the Chalk Grasslands of Eastern Westphalia (Germany) and Implications for Conservation

The population biology of Maculinea rebeli Hirschke, 1904, on dry grassland biotypes in different successional stages was investigated in the summers of 1990 and 1991 in the district of Höxter (North Rhine–Westphalia, Germany). The population characteristics of M. rebeli were studied by mark-recapture and eggshell counts on the larval host plant Gentiana cruciata. Pitfall traps, ant baits, excavating and counting of ant nests were used to examine the Formicidae community and the nest density of Myrmica sabuleti. In 1990, the total population of M. rebeli was estimated as 528 individuals, with subpopulations varying from 2 to 273 individuals. Populations existed in areas differing in size and vegetation structure. However, the limiting factor for population size was the density of the host ant population. The differences in population size did not depend on the size of the habitat or the density of the larval food plant. The butterflies can switch their host. In the absence of M. schenki, the colonies of M. sabuleti can maintain M. rebeli populations. Adult males and females have a maximum life expectancy of 13 days. The females prefer to oviposit on G. cruciata plants of 10–30cm height. Only plants which stuck out of the surrounding vegetation were oviposited on. The average number of eggs deposited per female was 100–150. Low density populations are probably most threatened. Therefore, future protective measures should work towards further maintaining and optimizing the habitats of the small populations, as well as creating the prerequisites so that dense stable populations of M. rebeli can develop.     

Chemical and physical-chemical characteristics of dietary fibres from Ulva lactuca (L.) Thuret and Enteromorpha compressa (L.) Grev.

Dietary fibres from Ulva lactuca (L.) Thuret (sea lettuce) and Enteromorpha compressa (L.) Grev. (A.O. nori) were measured according to a ‘standard’ method and a ‘physiological’ protocol simulating the gastric and intestinal environments. U. lactuca contained 15.8–8.0% soluble and 24.2–32.6% insoluble fibres according to the ‘standard’ and ‘physiological’ methods, respectively. For E. compressa, these values were 14.9–15.9 and 21.6–28.7%, respectively. For both algae, the composition suggests that the soluble fibres were xylorhamnoglycuronans sulphates and insoluble fibres were essentially composed of glucans. No marked chemical compositional variation was observed between soluble fractions extracted under the simulated gastric and intestinal conditions. Fibres in both algae are hydrophilic but the water holding capacities were higher after extraction of soluble fibres (5.5–9.5 g g⁻¹ for the dry algae; 14.0–16.0 g g⁻¹ for the standard insoluble fibres). Water soluble fibres demonstrated low intrinsic viscosities at 37 °C in buffers, particularly those from E. compressa (36.0–36.5 ml g⁻¹), and was affected by pH for those of U. lactuca (147.5 ml g⁻¹ at pH 3.0 and 175.0 ml g⁻¹ at pH 7.3).     

Barnacle growth rate on artificial substrate in the Salton Sea,California

The Salton Sea is one of the few saline, inland lakes in the world with a population of barnacles, Balanus amphitrite. It is also one of California’s most impaired water bodies due to excessive nutrient loading which leads to phytoplankton blooms and low dissolved oxygen. Currently, B. amphitrite growth is limited due to lack of hard substrate in and around the Sea. We have hypothesized that artificial substrate could support the growth of B. amphitrite and their filter-feeding would lead to improved water quality. Periodic harvesting of the barnacles would result in the permanent removal of nitrogen and phosphorus from the Sea. A 44-day in-situ experiment was carried out in the Salton Sea to assess the rate of barnacle growth and phosphorus and nitrogen sequestration on burlap sheets suspended vertically from a floating line. Burlap panels were collected weekly and the barnacles analyzed for Ca, total-P, inorganic-P, total-N, total-C, CaCO₃, and organic matter content. After 44 days of growth, the barnacle mats weighed 7.4 kg m⁻² on a dry weight basis, with 80% of the mass as shell material. The nutrient sequestration was 9.4 g P m⁻² and 100 g N m⁻². Approximately half of the P was inorganic and appears to be coprecipitated with the calcium carbonate shell material. Results indicate that harvesting barnacles grown on artificial substrate in the Salton Sea would not be an effective method for removing N or P from the lake because of the relative proportions of shell material and organic material. Guest editor: S. H. Hurlbert The Salton Sea Centennial Symposium. Proceedings of a Symposium Celebrating a Century of Symbiosis Among Agriculture, Wildlife and People, 1905–2005, held in San Diego, California, USA, March 2005