Comparison of the Recovery of Escherichia coli from Frozen Foods and Nutmeats by Confirmatory Incubation in EC Medium at 44.5 and 45.5 C

The productivity of confirmatory EC broth for the isolation of fecal Escherichia coli was determined at 44.5 and 45.5 C. A variety of frozen pre-cooked foods and an assortment of nutmeats were examined after primary incubation in Lauryl Sulfate Tryptose (LST) broth. In 85.3% of the cases, the parallel tubes of EC broth incubated for 24 hr at 44.5 and 45.5 C gave rise to identical E. coli responses of positive, false positive, and negative. The remaining 14.7% of the reactions represent the qualitative difference between the two temperatures. The EC test at 45.5 C was more specific for E. coli, since two- to threefold fewer false positives were produced at this temperature than at 44.5 C. However, fecal E. coli recoveries were slightly higher (4%) at the lower temperature. Incubating the EC tubes from the interval of 24 to 48 hr gave rise to an additional 4.3% of E. coli recovery, but this was accompanied by an excessive production of false positives (75.9%), representing a 3.5-fold decrease in specificity. It is recommended that, in the confirmatory use of EC broth in the examination of frozen foods and nutmeats for the recovery of fecal E. coli, the test be made at 45.5 C in a water bath and limited to 24 hr of incubation only, to insure optimal specificity. During the study, a “fixed” productivity ratio was noted; E. coli⁺/LST⁺ equaled approximately one-fourth or 25%. The significance of this ratio is discussed.     

Salmonella Survival on Pecans as Influenced by Processing and Storage Conditions

Survival of Salmonella senftenberg 775W, S. anatum, and S. typhimurium during exposure to currently practiced, as well as abusive, pecan processing and storage conditions was studied. Thermal treatments normally carried out during the processing of pecans are inadequate to consistently destory salmonellae in highly contaminated inshell nuts. Pecan nut packing tissue was toxic to salmonellae, thus affording some protection against high initial contamination and subsequent survival of the organisms. Examinations of inoculated inshell pecans stored at -18, -7, 5, and 21 C for up to 32 weeks revealed that the extent of survival was inversely correlated to the storage temperature. S. senftenberg 775W and S. anatum were not detectable on inshell nuts after 16 weeks of storage at 21 C. Little decrease in viable population of the three species was noted on inoculated pecan halves stored at -18, -7, and 5 C for 32 weeks. Due to organoleptic quality deterioration in pecan nutmeats at elevated temperatures, sterilization methods other than thermal treatment appear to be required for the elimination of viable salmonellae from pecan nuts.     

Resilience and elasticity of intertidal communities in response to harvesting of the alien mussel Mytilus galloprovincialis

Besides the direct impacts of exploitation on target species, indirect effects on non-target species are unavoidable and find expression in changes in community structure. We quantified the effects of experimental harvesting of Mytilus galloprovincialis on intertidal communities on the South African west coast. In the mid- and low-shore, four months of harvesting at intensities greater than F = 0.3 and F = 0.6 respectively, resulted in significant changes in community composition. These changes were driven by progressively greater spatial dominance by the macroalgae Cladophora flagelliformis, Porphyra capensis and Ulva species as harvesting intensity increased. Four months after cessation of harvesting, community structure had not recovered and even areas subjected to as little as F = 0.3 supported significantly altered communities in both zones. The fact that substantial community changes were induced by even low-intensity exploitation is indicative of low resilience to harvesting. The densities and cover of the dominant taxa returned to a pre-harvest state 16 months after the cessation of harvesting, but multivariate analyses indicated that the overall community composition required 32 months for Cover Letter full recovery. Although these communities displayed elasticity within three years, it is recommended that should a M. galloprovincialis fishery be established in the region, harvesting be implemented at a maximum intensity of F = 0.3. This approach would maximise yields and protect associated intertidal communities.     

Cunaxidae (Acari: Prostigmata) diversity and population dynamics in garlic (Allium sativum) crop fields

Agroecosystems are altered systems whose soil structure has changed affecting the dynamics of soil organisms. This paper aims at evaluation of the effects of garlic farming practices on phenology, richness, abundance, composition and diversity of soil-dwelling Cunaxidae. Ten pilot plots in Guanajuato State were sampled from August 2002 to July 2005, every month, 8 months per year. Ten soil samples (1 kg) were taken from each plot and extracted in Berlese-Tullgren funnels. A total of 108 cunaxids were found, belonging to 11 species. Neocunaxoides andrei was the most abundant, and Cunaxa evansi and Armascirus sp. were least abundant. Relative abundance was highest after harvesting and during plant growth, and lowest during planting. Dactyloscirus nicobarensis and D. candylus were present from planting to harvesting. According to Sörensen’s similarity coefficient between cultivation stages, Cunaxidae communities were similar during plant growth and harvesting, sharing 80 % of the species. The highest abundance and diversity were found in 2004, during and after harvesting. Cunaxid species increased over 100 % from planting to the harvesting phase, suggesting that they play an important role in the soil agrosystems food web. Species composition and diversity in cunaxid communities present in garlic crop fields varied with agricultural phase, but little change was observed among the years studied. All species found in this study are new records for the state of Guanajuato and for the garlic crop fields.     

An improved method for determining phytoplankton chlorophyll a concentration without filtration

The common and routine procedure for the quantification of chlorophyll a (chl a) in aquatic studies has a series of steps. Here, we sought to find optimal conditions for phytoplankton cell harvesting, chl a extraction, and chl a measurement and calculation, to find an effective, cost-saving, safe, and environment-friendly procedure for determining phytoplankton chl a concentration. We replaced the traditional GF/C filters with inorganic polymer flocculants (IPFs) and clay for phytoplankton harvesting, and then various solvents (acetone, ethanol, DMF, and DMSO), IPFs (PAC, PFS, and PAFS) and clay were tested for their suitability for chl a extraction, with or without homogenization at different temperatures for different extraction durations. About 0.3–1.0 g l^?1 of PAC or PFSA combined with 1.0–2.5 g l^?1 clay were found to provide optimal conditions in terms of yield and cost for phytoplankton cell harvesting from water samples. Based on our results, we recommend flocculation and centrifugation instead of glass-fiber membrane filtration for harvesting phytoplankton cells from environmental water samples, 95% ethanol for chl a extraction without homogenization and heating, and spectrophotometry to determine chl a concentration.     

Who Harvests and Why? Characteristics of Guatemalan Households Harvesting Xaté (Chamaedorea ernesti-augusti)1

Who Harvests and Why? Characteristics of Guatemalan Households Harvesting Xaté (Chamaedorea ernesti-augusti). Cultivation of harvested species is frequently proposed as a conservation strategy to reduce wild harvesting pressure and improve local livelihoods. The success of this approach is likely to be influenced by harvesters’ socioeconomic characteristics. Our study focuses on illegal harvesting of a palm species (Chamaedorea ernesti-augusti, locally known as xaté), by Guatemalans in the largely Belizean Greater Maya Mountains. We surveyed 222 households in nine Guatemalan villages close to the Belize/Guatemala border. With this sample we estimated the current intensity of illegal harvesting by Guatemalans in Belize, the characteristics of harvesting households, and their perceptions of the enforcement level of harvesting laws. We estimated that 26 % of households in the study area actively harvest. Harvesting households owned less land than non-harvesting households. Harvesters are aware that harvesting in Belize is illegal and of the sanctions for harvesting. However, incomes from xaté harvesting were favorable compared to alternative available activities and there were few barriers to entry. We conclude that successful conservation interventions promoting cultivation need to take account of existing harvester characteristics and constraints. Lack of secure land tenure means that cultivation is not a feasible alternative for many harvesting households.     

Sustainable utilization of woodrose-producing mistletoes (Loranthaceae) in South Africa

Pedistylis galpinii and Erianthemum dregei produce woodrose outgrowths at attachment points with host trees. In some rural areas of southern Africa, woodroses are sold as curios. The socio-economics related to woodrose harvesters were investigated via interview schedules and field survey. Harvesting is not detrimental to hosts as only branches infected with mistletoes are cut. Over half the harvesters interviewed reported harvesting both live and dead mistletoes while 20% used only dead ones. The density of dead mistletoes could satisfy present demand. Such sustainable harvesting practices (only using dead woodroses) allow for woodrose harvesting according to calculated quotas. The median gross income per month generated from woodroses was estimated to be between US $38 and 90. Eleven percent of harvesters relied on woodroses as their only source of income. Marketing was relatively haphazard, involving informal selling at roadsides and unscheduled visits to retailers. The market for woodroses can be expanded and the potential exists to increase supply considerably on a sustainable basis.     

Comparative quantitative proteomics of prochlorococcus ecotypes to a decrease in environmental phosphate concentrations

Background

Goa is a coastal state in India and salt making is being practiced for many years. This investigation aimed in determining the culturable haloarchaeal diversity during two different phases of salt production in a natural solar saltern of Ribandar, Goa. Water and sediment samples were collected from the saltern during pre-salt harvesting phase and salt harvesting phase. Salinity and pH of the sampling site was determined. Isolates were obtained by plating of the samples on complex and synthetic haloarchaeal media. Morphology of the isolates was determined using Gram staining and electron microscopy. Response of cells to distilled water was studied spectrophotometrically at 600nm. Molecular identification of the isolates was performed by sequencing the 16S rRNA.

Results

Salinity of salt pans varied from 3-4% (non-salt production phase) to 30% (salt production phase) and pH varied from 7.0-8.0. Seven haloarchaeal strains were isolated from water and sediment samples during non-salt production phase and seventeen haloarchaeal strains were isolated during the salt production phase. All the strains stained uniformly Gram negative. The orange-red acetone extract of the pigments showed similar spectrophotometric profile with absorption maxima at 393, 474, 501 and 535 nm. All isolates obtained from the salt dilute phase were grouped within the genus Halococcus. This was validated using both total lipid profiling and 16S rRNA data sequencing. The isolates obtained from pre-salt harvesting phase were resistant to lysis. 16S rRNA data showed that organisms belonging to Halorubrum, Haloarcula, Haloferax and Halococcus genera were obtained during the salt concentrated phase. The isolates obtained from salt harvesting phase showed varied lysis on suspension in distilled water and /or 3.5% NaCl.

Conclusion

Salterns in Goa are transiently operated during post monsoon season from January to May. During the pre-salt harvesting phase, all the isolates obtained belonged to Halococcus sp. During the salt harvesting phase, isolates belonging to Halorubrum, Haloarcula, Haloferax and Halococcus genera were obtained. This study clearly indicates that Halococcus sp. dominates during the low salinity conditions.     

A review of light interception in plant stands from leaf to canopy in different plant functional types and in species with varying shade tolerance

Changes in the efficiency of light interception and in the costs for light harvesting along the light gradients from the top of the plant canopy to the bottom are the major means by which efficient light harvesting is achieved in ecosystems. In the current review analysis, leaf, shoot and canopy level determinants of plant light harvesting, the light-driven plasticity in key traits altering light harvesting, and variations among different plant functional types and between species of different shade tolerance are analyzed. In addition, plant age- and size-dependent alterations in light harvesting efficiency are also examined. At the leaf level, the variations in light harvesting are driven by alterations in leaf chlorophyll content modifies the fraction of incident light harvested by given leaf area, and in leaf dry mass per unit area (M _A) that determines the amount of leaf area formed with certain fraction of plant biomass in the leaves. In needle-leaved species with complex foliage cross-section, the degree of foliage surface exposure also depends on the leaf total-to-projected surface area ratio. At the shoot scale, foliage inclination angle distribution and foliage spatial aggregation are the major determinants of light harvesting, while at the canopy scale, branching frequency, foliage distribution and biomass allocation to leaves (F _L) modify light harvesting significantly. F _L decreases with increasing plant size from herbs to shrubs to trees due to progressively larger support costs in plant functional types with greater stature. Among trees, F _L and stand leaf area index scale positively with foliage longevity. Plant traits altering light harvesting have a large potential to adjust to light availability. Chlorophyll per mass increases, while M _A, foliage inclination from the horizontal and degree of spatial aggregation decrease with decreasing light availability. In addition, branching frequency decreases and canopies become flatter in lower light. All these plastic modifications greatly enhance light harvesting in low light. Species with greater shade tolerance typically form a more extensive canopy by having lower M _A in deciduous species and enhanced leaf longevity in evergreens. In addition, young plants of shade tolerators commonly have less strongly aggregated foliage and flatter canopies, while in adult plants partly exposed to high light, higher shade tolerance of foliage allows the shade tolerators to maintain more leaf layers, resulting in extended crowns. Within a given plant functional type, increases in plant age and size result in increases in M _A, reductions in F _L and increases in foliage aggregation, thereby reducing plant leaf area index and the efficiency of light harvesting. Such dynamic modifications in plant light harvesting play a key role in stand development and productivity. Overall, the current review analysis demonstrates that a suite of chemical and architectural traits at various scales and their plasticity drive plant light harvesting efficiency. Enhanced light harvesting can be achieved by various combinations of traits, and these suites of traits vary during plant ontogeny.     

Effects of experimental harvesting on recruitment of an alien mussel Mytilus galloprovincialis

Successful fisheries management is underpinned by an understanding of the processes that underlie the population dynamics of exploited stocks. This study considered the effects of experimental harvesting on recruitment of Mytilus galloprovincialis along the west coast of South Africa, where harvesting of this alien species is being contemplated. In particular, the role of settlement habitat availability in the form of adult mussels was analysed. To track the effects of a spectrum of harvesting intensities, five treatments were implemented: F = 0 (i.e. a control), F = 0.3, F = 0.6, F = 0.9 and F = 1. At these harvesting intensities 0%, 30%, 60%, 90% or 100% of mussel biomass was removed respectively at the outset of the experiment. A significant negative exponential relationship (p < 0.01) was found between M. galloprovincialis recruit density and harvesting intensity, with intensities greater than F = 0.3 dramatically reducing recruitment. This pattern was recorded throughout the intertidal zone and remained temporally constant over 2 years. Significant positive linear relationships (p < 0.01) between recruit density and adult mussel biomass or density indicate a strong correlation between availability of settlement habitat and recruitment. It is likely that the high recruit density recorded at low harvesting intensities (2000-20 000 per 0.01 m²) exceeds the level required for population maintenance. However, if settlement habitat is eliminated or significantly reduced, as was achieved by F = 0.3 or above, recruitment may become limiting. Thus, to protect stock replenishment, harvesting of M. galloprovincialis in this region should take place at intensities less than F = 0.3.     

The formation of bacteriochlorophyll · protein complexes of the photosynthetic apparatus of Rhodopseudomonas capsulata during early stages of development

Cells of Rhodopseudomonas capsulata cultivated at an oxygen partial pressure of 400 mmHg in the dark contained 0.1 nmol or less total bacteriochlorophyll per mg membrane protein. The bacteriochlorophyll was found in the reaction center (10 pmol bacteriochlorophyll/mg membrane protein) and in the light harvesting bacteriochlorophyll I but not in the light harvesting bacteriochlorophyll II. Formation of the photosynthetic apparatus in those cells was induced by incubation at a very low oxygen tension in the dark. Reaction center bacteriochlorophyll and light harvesting bacteriochlorophyll increased three fold after 60 min of incubation at 1–2 mmHg (pO₂). Light harvesting bacteriochlorophyll II increased strongly after 60 min and became dominating after 90 min of incubation. The total bacteriochlorophyll content doubled every 30 min, but synthesis of reaction center bacteriochlorophyll proceeded at much lower rates. Consequently the size of the photosynthetic unit (total bacteriochlorophyll/reaction center bacteriochlorophyll) increased from 15 to 52 during 150 min of incubation. The proteins of the photosynthetic apparatus were synthesized concomitantly with bacteriochlorophyll.Cells which were incubated at 0.5 mmHg (pO₂) do not grow but form the photosynthetic apparatus. During the first hours of incubation light harvesting bacteriochlorophyll I and reaction center bacteriochlorophyll were the dominant bacteriochlorophyll species, but light harvesting bacteriochlorophyll II was synthesized only in small amounts. Total bacteriochlorophyll and reaction center bacteriochlorophyll increased from 30 min up until 210 min of incubation more than 10 fold. The final concentrations of total bacteriochlorophyll and reaction center bacteriochlorophyll were 8.6 nmol and 0.26 nmol per mg membrane protein, respectively. The three protein components of the reaction centers (mol. wts. 28 000, 24 000 and 21 000) and the protein of the light harvesting I complex (mol. wt. 12 000) were incorporated simultaneously. The protein of band 1 (mol. wt. 14 000) which was present in the isolated light harvesting complex II, was synthesized only in very small amounts. The proteins of bands 3 and 4 (mol. wt. 10 000 and 8000) however, which were shown to be associated with light harvesting bacteriochlorophyll II, were synthesized in noticeable amounts as was light harvesting bacteriochlorophyll II. In addition a protein with an apparent molecular weight of 45 000 showed a strong incorporation of ¹⁴C-labeled amino acids. This protein comigrates with one protein which was found to be associated with a green pigment excreted during incubation at 0.5 Torr into the medium. The in vivo-absorption maxima of this pigment complex were 660, 590, 540, 417 and 400 nm. The succinate oxidase and the NADH oxidase seemed to be incorporated into the newly formed intracytoplasmic membrane only in very small amounts. Thus, reaction center and light harvesting bacteriochlorophyll and their associated proteins were simultaneously synthesized, whereas light harvesting complex II is the variable part of the photosynthetic apparatus.     

Incidence of Aflatoxin in California Almonds

In a survey of California almonds, aflatoxin was found in 14% of 74 samples of unsorted, in-shell almonds as received by the processor in 1972, but it occurred at very low levels (below 20 parts per billion [ppb]) in 90% of the contaminated samples. The overall proportion of individual nuts contaminated was especially low and is estimated with 95% probability to have been in the range of 1 nut/55,300 nuts to 1 nut/14,700 nuts. Aflatoxin contamination is not restricted to any particular section of the almond-growing region of California. Commercial sorting procedures are effective in removing most aflatoxin-contaminated nutmeats, since none of 26 samples of processed, whole nutmeats contained aflatoxin. In contrast, 13 of 27 samples of diced almonds were contaminated, but nine of these 13 samples contained less than 20 ppb. Only one of 25 samples of sliced nutmeats contained aflatoxin (4 ppb). Thus, aflatoxin incidence in almonds varies greatly with the category of finished product. The apparent high incidence in diced nutmeats is probably due mostly to the more uniform distribution of aflatoxin occurring in this product (because of its small particle size) than that occurring in the other products. Sample size requirements for monitoring aflatoxin in almonds are discussed.     

Social and Ecological Characteristics of an Expanding Natural Resource Industry: <Emphasis Type="Italic">Aloe</Emphasis> Harvesting in South Africa

Sustainable harvesting practices are important for conserving plant species and their habitats, but also the livelihoods of those that depend on them. Aloe ferox, a valuable natural resource harvested for its leaves, is the focus of a recent rural development initiative in the Eastern Cape of South Africa. This has the potential to benefit poor residents through a high-value, sustainable, export market. We characterize the social and ecological components of the system, in order to evaluate the potential for effective natural resource management. We interviewed aloe tappers to obtain information on their dependence on the A. ferox industry and harvesting practices. We assessed the harvesting pressure on A. ferox populations, sampling plants at three plots positioned along each of four transects at distances of 1.5, 3.45, and 7 km from the factory, grouping plants into two size classes: small (height <0.5 m) and large (>0.5 m). We investigated the influence of proximity to the factory and plant size class on the likelihood and intensity of harvest. The majority of aloe tappers were women, unemployed, and in receipt of government welfare grants, and the main reason for harvesting A. ferox was to generate a cash income for their daily needs. Training guidelines did not appear to be followed, with aloe tappers leaving on average 6 leaves, rather than the recommended 18–20 leaves, allowing insufficient time to pass between harvesting episodes and harvesting outside of the prescribed wetter periods. In line with training guidelines, aloe tappers were targeting larger plants; however, against recommendations, smaller plants were also regularly harvested. Harvesting pressure decreased with increasing distance from the factory. We discuss requirements to ensure A. ferox is harvested at sustainable levels in the region, particularly in light of a possible regional roll out of the program, and provide recommendations for regulating use and better training.     

Biogenesis and light regulation of the major light harvesting chlorophyll-protein of diatoms

The apoprotein of the major light harvesting pigment-protein complex from the diatom Phaeodactylum tricornutum (UTEX 646) is composed of two similar polypeptides of 17.5 and 18.0 kilodaltons (kD). The in vivo synthesis of these polypeptides is inhibited by the 80s protein synthesis inhibitor cycloheximide, but not by the 70s ribosome inhibitor chloramphenicol. When total poly(A)⁺ RNA was used in in vitro protein synthesis, a number of polypeptides were synthesized with a dominant product at 22 kD. When the polypeptides were immunoprecipitated with monospecific antibodies to the 17.5 and 18.0 polypeptides, a single protein zone of 22 kD was detected. Immunoprecipitation with preimmune serum failed to precipitate detectable levels of protein at any relative molecular weight (M_r). These findings indicate that the two apoprotein polypeptides of the diatom light harvesting pigment-protein are translated from polyadenylated message on cytoplasmic ribosomes as either a single or two (or more) similar M_r precursor proteins. These findings also suggest that this protein is encoded in the nucleus.

Photosynthetic light adaptation features of P. tricornutum UTEX 646 indicate that it responds to low light by increasing cell size and numbers of photosystem I and II reaction centers per cell, but does not change photosynthetic rate per cell or photosynthetic unit sizes significantly. When low light cells are exposed to higher photon flux densities, the in vivo incorporation of label into the apoprotein of the light harvesting complex decreases. In contrast, high light grown cells show rapid (<3 hour) increases in apoprotein synthesis when exposed to low light levels. This is the first demonstration of a specific role of photon flux density in regulating the synthesis of a major light harvesting pigment-protein during photosynthetic light adaptation.

     

Anthropogenic Landscape in Southeastern Amazonia: Contemporary Impacts of Low-Intensity Harvesting and Dispersal of Brazil Nuts by the Kayapó Indigenous People

Brazil nut, the Bertholletia excelsa seed, is one of the most important non-timber forest products in the Amazon Forest and the livelihoods of thousands of traditional Amazonian families depend on its commercialization. B. excelsa has been frequently cited as an indicator of anthropogenic forests and there is strong evidence that past human management has significantly contributed to its present distribution across the Amazon, suggesting that low levels of harvesting may play a positive role in B. excelsa recruitment. Here, we evaluate the effects of Brazil nut harvesting by the Kayapó Indigenous people of southeastern Amazonia on seedling recruitment in 20 B. excelsa groves subjected to different harvesting intensities, and investigated if management by harvesters influences patterns of B. excelsa distribution. The number of years of low-intensity Brazil nut harvesting by the Kayapó over the past two decades was positively related to B. excelsa seedling density in groves. One of the mechanisms behind the higher seedling density in harvested sites seems to be seed dispersal by harvesters along trails. The Kayapó also intentionally plant B. excelsa seeds and seedlings across their territories. Our results show not only that low-intensity Brazil nut harvesting by the Kayapó people does not reduce recruitment of seedlings, but that harvesting and/or associated activities conducted by traditional harvesters may benefit B. excelsa beyond grove borders. Our study supports the hypothesis that B. excelsa dispersal throughout the Amazon was, at least in part, influenced by indigenous groups, and strongly suggests that current human management contributes to the maintenance and formation of B. excelsa groves. We suggest that changes in Brazil nut management practices by traditional people to prevent harvesting impacts may be unnecessary and even counterproductive in many areas, and should be carefully evaluated before implementation.     

Initial responses of rove and ground beetles (Coleoptera,Staphylinidae, Carabidae) to removal of logging residues following clearcut harvesting in the boreal forest of Quebec,Canada

Increased interest in biomass harvesting for bioenergetic applications has raised questions regarding the potential ecological consequences on forest biodiversity. Here we evaluate the initial changes in the abundance, species richness and community composition of rove (Staphylinidae) and ground beetles (Carabidae), immediately following 1) stem-only harvesting (SOH), in which logging debris (i.e., tree tops and branches) are retained on site, and 2) whole-tree harvesting (WTH), in which stems, tops and branches are removed in mature balsam fir stands in Quebec, Canada. Beetles were collected throughout the summer of 2011, one year following harvesting, using pitfall traps. Overall catch rates were greater in uncut forest (Control) than either stem-only or whole-tree harvested sites. Catch rates in WTH were greater than SOH sites. Uncut stands were characterized primarily by five species: Atheta capsularis, Atheta klagesi, Atheta strigosula, Tachinus fumipennis/frigidus complex (Staphylinidae) and to a lesser extent to Pterostichus punctatissimus (Carabidae). Increased catch rates in WTH sites, where post-harvest biomass was less, were attributable to increased catches of rove beetles Pseudopsis subulata, Quedius labradorensis and to a lesser extent Gabrius brevipennis. We were able to characterize differences in beetle assemblages between harvested and non-harvested plots as well as differences between whole tree (WTH) and stem only (SOH) harvested sites where logging residues had been removed or left following harvest. However, the overall assemblage response was largely a recapitulation of the responses of several abundant species.     

Potential impact of harvesting on the population dynamics of two epiphytic bromeliads

Large numbers of epiphytes are extracted from cloud forests for ornamental use and illegal trade in Latin America. We examined the potential effects of different harvesting regimes on the population dynamics of the epiphytic bromeliads Tillandsia multicaulis and Tillandsia punctulata. The population dynamics of these species were studied over a 2-year period in a tropical montane cloud forest in Veracruz, Mexico. Prospective and retrospective analyses were used to identify which demographic processes and life-cycle stages make the largest relative contribution to variation in population growth rate (λ). The effect of simulated harvesting levels on population growth rates was analysed for both species. λ of both populations was highly influenced by survival (stasis), to a lesser extent by growth, and only slightly by fecundity. Vegetative growth played a central role in the population dynamics of these organisms. The λ value of the studied populations did not differ significantly from unity: T. multicaulis λ (95% confidence interval) = 0.982 (0.897–1.060) and T. punctulata λ = 0.967 (0.815–1.051), suggesting population stability. However, numerical simulation of different levels of extraction showed that λ would drop substantially even under very low (2%) harvesting levels. Matrix analysis revealed that T. multicaulis and T. punctulata populations are likely to decline and therefore commercial harvesting would be unsustainable. Based on these findings, management recommendations are outlined.     

Antheraxanthin, a light harvesting carotenoid found in a chromophyte alga

The pigments of the chromophyte freshwater alga, Chrysophaera magna Belcher were analyzed by thin layer chromatography (TLC) and high performance liquid chromatography (HPLC) to reveal the presence of chlorophylls a and c, β-carotene, fucoxanthin, and antheraxanthin. The presence of antheraxanthin was verified by comparison of TLC R_F values, HPLC retention times, and absorption features to those of authentic, synthetic antheraxanthin. Antheraxanthin accounted for about 15% of the total carotenoid content of C. magna. The molar ratio of the major carotenoids was antheraxanthin:fucoxanthin:β-carotene, 1:2.3:3.3. The whole-cell absorption spectrum revealed a broad band between 470 and 520 nanometers which was attributed to fucoxanthin and antheraxanthin in vivo. Upon extraction in hydrocarbon, this broad absorption region was lost. The in vivo fluorescence excitation spectrum for 680 nm emission revealed the energy transfer activities and light harvesting roles of chlorophylls a and c, and fucoxanthin. In addition, an excitation band was resolved at 487 nanometers which could be attributed only to antheraxanthin. Comparison of whole-cell fluorescence excitation spectra of C. magna with the diatom Phaeodactylum tricornutum, which possesses fucoxanthin but not antheraxanthin, supports the assignment of the 487 nm band to antheraxanthin. This is the first report of a photosynthetic light harvesting function of the xanthophyll, antheraxanthin. This carotenoid broadens the absorption cross-section for photosynthesis in C. magna and extends light harvesting into the green portion of the spectrum.