Effects of feeding level and body size on food utilization of the freshwater snail Pila globosa

Food supply caused an increase in the overall energy budget of all size groups of Pila globosa. Feeding rate increased from 3.4 to 28.7, 2.0 to 19.1 and 0.2 to 7.2 mg/g/day in young, intermediate and old snails respectively. The corresponding increase in body weight (growth rate) ranged from 1.3 to 2.7, 0.5 to 1.5 and 0.4 to 0.5 mg/g/day. When compared with the other two groups, maximum values were recorded for young P. globosa, i.e. an increase in size (ageing) caused a decrease in the energy budget. Data obtained for the maintenance, optimum and maximum feeding rates for the young P. globosa were 12.0, 22.0 and 28.8 mg/g/day. The corresponding values for the intermediate and old snails were 7.4, 14.0 and 19.0 mg/g/day and 4.1, 5.6 and 7.2 mg/g/day. With the increase in body weight, a progressive reduction in the slope of the regression lines was noticed in the body weight-conversion rate relationship.Paper presented in the first Indian Conference on Ecology and Environmental Sciences, University of Rajasthan, Jaipur (1980).     

Zooplankton grazing on Phaeocystis: a quantitative review and future challenges

The worldwide colony-forming haptophyte phytoplankton Phaeocystis spp. are key organisms in trophic and biogeochemical processes in the ocean. Many organisms from protists to fish ingest cells and/or colonies of Phaeocystis. Reports on specific mortality of Phaeocystis in natural plankton or mixed prey due to grazing by zooplankton, especially protozooplankton, are still limited. Reported feeding rates vary widely for both crustaceans and protists feeding on even the same Phaeocystis types and sizes. Quantitative analysis of available data showed that: (1) laboratory-derived crustacean grazing rates on monocultures of Phaeocystis may have been overestimated compared to feeding in natural plankton communities, and should be treated with caution; (2) formation of colonies by P. globosa appeared to reduce predation by small copepods (e.g., Acartia, Pseudocalanus, Temora and Centropages), whereas large copepods (e.g., Calanus spp.) were able to feed on colonies of Phaeocystis pouchetii; (3) physiological differences between different growth states, species, strains, cell types, and laboratory culture versus natural assemblages may explain most of the variations in reported feeding rates; (4) chemical signaling between predator and prey may be a major factor controlling grazing on Phaeocystis; (5) it is unclear to what extent different zooplankton, especially protozooplankton, feed on the different life forms of Phaeocystis in situ. To better understand the mechanisms controlling zooplankton grazing in situ, future studies should aim at quantifying specific feeding rates on different Phaeocystis species, strains, cell types, prey sizes and growth states, and account for chemical signaling between the predator and prey. Recently developed molecular tools are promising approaches to achieve this goal in the future.     

Effects of chlorophyll concentration and temperature variation on the reproduction and survival of Temora longicornis (Copepoda, Calanoida) in the Eastern English Channel

The influence of temperature and chlorophyll concentration on egg production, hatching success, female survival and body size of the copepod Temora longicornis was investigated in situ in the coastal waters of the Eastern English Channel. Twenty samples were collected between February and July 2003 three to four times per month. The maximum daily level of egg production of 75.5 eggs female⁻¹ was observed in March, with minima of 10 eggs female⁻¹ in February and July. Between February and March egg production increased with chlorophyll concentration. At the end of March a decrease in egg production corresponded to a strong increase in chlorophyll concentration that indicated a Phaeocystis-dominated bloom. After this period egg production closely followed the temporal variation in chlorophyll concentration with a maximum of 55.3 eggs female⁻¹ in April during a second peak of chlorophyll concentration. Hatching success varied between 60% and 80% and was not influenced by chlorophyll concentration, in situ temperature or any other biological parameter considered in this study. Increases in temperature from February to July paralleled a decrease in body length and an increase in the percentage of spawning females. Mean female survival followed the variation of both temperature and chlorophyll concentration only between April and July. Temperature and chlorophyll concentration affected the reproductive parameters of T. longicornis differently. Female survival and body size were negatively correlated with temperature, while the highest chlorophyll concentrations were not always favourable for egg production. Therefore the quality of food should not be associated with chlorophyll quantity. Furthermore, the maximum values of egg production in this study are the highest recorded for T. longicornis. This study, conducted for the first time in the Eastern English Channel, showed high levels of productivity of T. longicornis despite a decrease of egg production during a Phaeocystis sp. dominated bloom in April.     

Diurnal and spatial patterns of Phytoseiidae in the citrus canopy

Phytoseiid mites were sampled in a grapefruit orchard at various times of the day to study their diurnal and seasonal distributions in the tree canopy. Samples were collected on 14, 20 and 28 October 1999 at 2 h intervals from 0600 to 2200 h. Similar samples were collected in a grapefruit orchard at 3 h intervals from 0600 to 2100 h on 9 and 16 March and on 17 and 24 August 2000 for phytoseiid mites. No differences in numbers of phytoseiid motiles were observed among the hours sampled in any of the three months. However, significant differences were observed in the number of phytoseiids per leaf based on location within the tree (eastern, western sides of the canopy or interior). Interior leaves collected in March and August 2000 had higher numbers of phytoseiids than exterior leaves taken from either the eastern or western sides of the tree canopy. Phytoseiids were more abundant in the March 2000 samples (mean = 1.10 phytoseiids/leaf) than in either October 1999 or August 2000 samples (mean = 0.16 and 0.19 phytoseiids/leaf, respectively). Prevalent phytoseiid species were Typhlodromalus peregrinus (Muma) (42.1%) and Iphiseiodes quadripilis (Banks) (50.4%) in October 1999, Typhlodromalus peregrinus (Muma) (76.2%) in March 2000, and Euseius mesembrinus (Dean) (54%) in August 2000.     

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.     

The effect of host spatial distribution on patterns of parasitism by Nasonia vitripennis

Patterns of parasitism of Calliphora sp. pupae by Nasonia vitripennis (Walker) (Hymenoptera: Pteromalidae) are explored under various conditions of host aggregation. Increasing the hosts' spatial aggregation decreased the number of hosts actually parasitised but had no significant effect on the total number of hosts attacked. Increasing host aggregation also resulted in a smaller parasitoid population with a more male biased sex ratio.

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Résumé Nous avons examiné les effets de différents niveaux d'agrégation des hôtes (pupes de Calliphora) sur l'efficacité parasitaire de Nasonia vitripennis. Une augmentation de l'agrégation des pupes a diminué le nombre d'hôtes parasités bien que le nombre de pupes attaquées ait été peu modifié. Cette différence a été attribuée à un accroissement des interactions comportementales entre les parasitoïdes et à une tendance au superparasitisme plus élevée lors des distributions les plus agrégatives. Plus les hôtes étaient concentrés, moins l'effectif de parasitoïdes achevant leur développement et émergeant était important. La fréquence des males a augmenté avec la concentration des pupes. Nous avons estimé que les facteurs déterminants ont été les interactions comportementales entre femelles et leur aptitude à modifier le taux sexuel de leur descendance immédiate.Nous en avons conclu que N. vitripennis est peut-être mieux adaptée aux populations d'hôtes distribuées au hasard, type de distribution le plus vraisemblable dans les populations naturelles.

     

The effect of drought stress on chlorophyll fluorescence in Lolium-Festuca hybrids

The effects of drought on photochemical efficiency of PSII in leaves of 22 hybrids of Festuca pratensis × Lolium multiflorum and Festuca pratensis × Lolium perenne and of Festuca pratensis cv. Skra were investigated. A significant decrease of electron transport efficiency (about 25%) in PSII (Φ_PSII) was not found before 9 days of seedling growth in hydroponics with water potential (Ψ_w) equal to −0.8 MPa (simulated “soil drought”). The decrease of Φ_PSII was similarly related to that of excitation energy capture by open PSII reaction centre (Fv’/Fm’) and also to the decrease of the proportion of oxidized to reduced Q_A (photochemical fluorescence quenching, q_p). According to the drought prolongation, variation of all parameters of fluorescence between genotypes significantly increased. The seedlings of some genotypes were able to recover electron transport efficiency in PSII after increasing water potential in nutrient solution (removing the “soil drought”). When plants grew in containers with soil and 4 genotypes with the highest sensitivity of electron transport to drought (S) as well as 4 genotypes with the highest tolerance (T) were compared 17 days after watering ceased, Ψ_w in leaves considerably decreased, but the differences between S and T genotypes were often not significant in this respect. The differences between S and T genotypes, as values of Fv/Fm were concerned, also appeared small (about 5%), similarly as that of Fv’/Fm’ (5%), q_p (12%) and Φ_PSII (about 15%). Drought stress increased non-photochemical quenching of chlorophyll fluorescence (NPQ) 15 to 47% and this could protect the PSII reaction centres from damages because of energy excess. The increase of NPQ was not closely connected with drought resistance of plants because it was similar in some genotypes tolerant to dehydration as well as in sensitive ones. The results of the experiments suggest that resources of genetic variability in Festulolium may be sufficient for revealing differences between genotypes on the basis of measurement of chlorophyll a fluorescence, as far as their tolerance to soil drought is concerned. As the tolerance of PSII against drought is high, the determinations of fluorescence should be performed rather under severe stress. Such methods seem to be useful for selection of genotypes with high drought tolerance as well as with the ability to at least partial repairing of PSII after drought.     

The temporal and spatial patterns of protozooplankton abundance in a eutrophic temperate lake

The temporal and spatial distribution of planktonic protozoa of Esthwaite, a eutrophic lake, was investigated at 7–10 day intervals between February to October 1988. Sarcodine protozoa were of little significance, the plankton was dominated by ciliates and flagellates. Ciliate density peaked in late May to early June with densities reaching 9.2 × 10³ 1^-1. There was considerable variation in spatial distribution and greatest species diversity occurred in March/April. After the establishment of summer stratification the planktonic ciliates were confined to water of >25% oxygen saturation in the water column. Oligotrichs, particularly the genus Strombidium and tintinnids, and peritrichs dominated the ciliate assemblages. There was no correlation between chlorophyll a concentrations and ciliate numbers, but a correlation was apparent between ciliate numbers and flagellate density. There were significant differences between the protozooplankton communities at the different sampling sites in the lake.     

Influence of dissimilarities in temporal and spatial N-uptake patterns on15N-based estimates of fixation and transfer of N in ryegrass-clover mixtures

The temporal N-uptake patterns of white clover (Trifolium repens L.) mixed with perennial ryegrass (Lolium perenne L.) and of red clover (Trifolium pratense L.) mixed with Italian ryegrass (Lolium multiflorum Lam.) were determined in successive harvests of herbage within the growth cycles of a ley established near Zürich (Switzerland). Rooting patterns were examined by injecting¹⁵N-fertilizer at soil depths ranging from 10 to 40 cm. The results were analyzed to determine the effect of variations in time and depth of N-uptake on the¹⁵N-based measurement of N from symbiosis (N_sym) and N from transfer (N_trans).Grasses in mixture appeared to have deeper rooting systems than grass monocultures, which led to an overestimation of N transfer from white clover to perennial ryegrass if¹⁵N was spread on the soil surface.White clover generally lagged behind grass in soil N- uptake. Soil N-uptake of red clover slowed down before that of the grass because % N_sym almost reached 100% during the second half of each growth cycle. However, the effect of these dissimilarities on the seasonal average of %N_sym did not exceed 2%.It is concluded that at the observed high levels of N₂ fixation, failure to account for the N-uptake patterns of the test and reference crops only slightly affected the estimates of % N_sym and % N_trans, and did not invalidate the observed differences between species.     

The carbohydrates of Phaeocystis and their degradation in the microbial food web

The ubiquity and high productivity associated with blooms of colonial Phaeocystis makes it an important contributor to the global carbon cycle. During blooms organic matter that is rich in carbohydrates is produced. We distinguish five different pools of carbohydrates produced by Phaeocystis. Like all plants and algal cells, both solitary and colonial cells produce (1) structural carbohydrates, (hetero) polysaccharides that are mainly part of the cell wall, (2) mono- and oligosaccharides, which are present as intermediates in the synthesis and catabolism of cell components, and (3) intracellular storage glucan. Colonial cells of Phaeocystis excrete (4) mucopolysaccharides, heteropolysaccharides that are the main constituent of the mucous colony matrix and (5) dissolved organic matter (DOM) rich in carbohydrates, which is mainly excreted by colonial cells. In this review the characteristics of these pools are discussed and quantitative data are summarized. During the exponential growth phase, the ratio of carbohydrate-carbon (C) to particulate organic carbon (POC) is approximately 0.1. When nutrients are limited, Phaeocystis blooms reach a stationary growth phase, during which excess energy is stored as carbohydrates. This so-called overflow metabolism increases the ratio of carbohydrate-C to POC to 0.4–0.6 during the stationary phase, leading to an increase in the C/N and C/P ratios of Phaeocystis organic matter. Overflow metabolism can be channeled towards both glucan and mucopolysaccharides. Summarizing the available data reveals that during the stationary phase of a bloom glucan contributes 0–51% to POC, whereas mucopolysaccharides contribute 5–60%. At the end of a bloom, lysis of Phaeocystis cells and deterioration of colonies leads to a massive release of DOM rich in glucan and mucopolysaccharides. Laboratory studies have revealed that this organic matter is potentially readily degradable by heterotrophic bacteria. However, observations in the field of accumulation of DOM and foam indicate that microbial degradation is hampered. The high C/N and C/P ratios of Phaeocystis organic matter may lead to nutrient limitation of microbial degradation, thereby prolonging degradation times. Over time polysaccharides tend to self-assemble into hydrogels. This may have a profound effect on carbon cycling, since hydrogels provide a vehicle to move DOM up the size spectrum to sizes subject to sedimentation. In addition, it changes the physical nature and microscale structure of the organic matter encountered by bacteria which may affect the degradation potential of the Phaeocystis organic matter.     

Effects of manganese on chlorophyll fluorescence in epiphytic cyano- and chlorolichens

Incubation with 10 mM MnCl₂ for 1 h decreased the effective quantum yield of photochemical energy conversion in photosystem 2 in the bipartite chlorolichen Hypogymnia physodes as well as in the bipartite cyanolichens Leptogium saturninum and Nephroma helveticum, but not in the tripartite lichen Lobaria pulmonaria. Among the bipartite species, Mn sensitivity increased in the order H. physodes < N. helveticum < L. saturninum. This equals the sequence heteromerous chlorolichen < heteromerous cyanolichen < homoiomerous (gelatinous) cyanolichen. MnCl₂ reduced non-photochemical quenching of chlorophyll fluorescence in the bipartite cyanolichens and in H. physodes; in the latter, however, this decrease was limited to light intensities above the adapted growth light intensity. Photochemical quenching was increased in H. physodes, but reduced in the bipartite cyanolichens. The results indicate that the bipartite cyanolichens L. saturninum and N. helveticum are even more sensitive to high Mn concentrations than the chlorolichen H. physodes, the low Mn tolerance of which has been already demonstrated. This agrees with results of field studies from western North America, where conifer bark under cyanolichens (including L. saturninum and N. helveticum) was found to contain less Mn than bark which only supported chlorolichens. The high sensitivity of the bipartite cyanolichens probably results from high sensitivity of the Nostoc photobiont. The high Mn tolerance of L. pulmonaria is probably not due to its being a tripartite lichen, but might be caused by high tolerance of the green-algal primary photobiont Dictyochloropsis, which is, however, not experimentally proven. The high Mn tolerance of the highly SO₂-sensitive L. pulmonaria shows that different mechanisms are responsible for Mn and SO₂ toxicity in lichens.     

Temporal and spatial patterns in the recruitment of Gibbula umbilicalis

Size/frequency samples have been taken from populations of the trochid gastropod Gibbula umbilicalis at a number of sites around the British Isles each year since 1978. In the North of Scotland, close to the limit of the species distribution, recruitment was generally poor and populations were sparse and dominated by large old individuals. While such poor recruitment may reflect the low density of adults and the shortage of nursery areas, a distinct temporal pattern of recruitment was also evident. At the start of our study, the majority of sites had population structures biased towards young animals implying that conditions for the settlement of larvae or their subsequent survival had been favourable over a wide area. In the years that followed only the enclosed Loch Eriboll regularly received substantial recruitment. Further to the south, in Wales and S.W. England, recruitment was usually more regular, populations were more dense and individuals smaller.     

Temporal and spatial patterns of spawning site use by two cavity-spawning darters in a Wisconsin stream

Synopsis There was partial spatial and complete temporal overlap of spawning by Etheostoma flabellare and E. nigrum in Marsh Creek, Wisconsin. E. flabellare tended to spawn at shallower depths than E. nigrum. Both species spawned over a greater range of depths in an area with few spawning sites (cavities under rocks or logs) than in an area where spawning sites were abundant. In the laboratory E. flabellare were able to prevent E. nigrum from occupying cavities they would have otherwise occupied. E. nigrum appear to be competitively inferior to E. flabellare in terms of spawning-site acquisition and retention, but possess several attributes that may allow them to persist in the presence of the latter.     

Seasonal patterns of pore-water nutrients, benthic chlorophyll a and sedimentary AVS in a macrobenthos-rich tidal flat

Monthly field investigations were carried out at controlled low-tide in an estuarine intertidal sandflat of the Seto Inland Sea (Japan) between January 1995 and April 1996. We assessed the spatial and temporal distribution of pore-water nutrient [NH ₄ ⁺ -N, (NO ₃ ⁻ + NO ₂ ⁻ )-N, PO ₄ ³⁻ -P and Si(OH)₄-Si], chlorophyll a (chl a) and acid-volatile sulphide (AVS) concentrations in the uppermost 0–10 cm sediment horizon, and evaluated their relationships with macrobenthic assemblages. Monthly hydrological data, nutrient and chl a concentrations in low-tide creek water adjacent to the flat were used as a complementary environmental characterisation of the study area. All different pore-water nutrients showed a 10 to > 30-fold variability between different layers and periods. NH ₄ ⁺ -N, PO ₄ ³⁻ -P and Si(OH)₄-Si concentrations were lowest in winter, progressively increased throughout spring and summer, and were highest between September and October, with a major increase at intermediate (4–8 cm) layers. In contrast, (NO ₃ ⁻ + NO ₂ ⁻ )-N concentrations, correlated positively with chl a, peaked in winter and sharply decreased with depth in all different seasons and in most occasions. Depth-integrated NH ₄ ⁺ -N, PO ₄ ³⁻ -P and Si(OH)₄-Si pools were correlated positively with biogenic nutrient flux calculated from the nutrient excretion rates of dominant bivalves Ruditapes philippinarum and Musculista senhousia. These relationships indicated rapid removal pathways of P, Si and N (i.e., every 0.1, 0.24 and 0.34 day, respectively), implying highly dynamic sediments. Based on the mass balance P = F + I, biogenic production (P) vs. diffusive flux (F) estimates suggested a predominant contribution of animal bioirrigation (I) to the upward flux of nutrients. AVS concentrations, correlated negatively with both (NO ₃ ⁻ + NO ₂ ⁻ )-N and chl a, showed a progressive increase from late summer throughout winter, subsequent to that of NH ₄ ⁺ -N, PO ₄ ³⁻ -P and Si(OH)₄-Si. The results indicate that in our study area the spatial and temporal distribution of pore-water nutrients, chl a and AVS in sediments are strongly interlinked and suggest that the metabolic processes (e.g., excretion, bio-deposition) and behavioural activities (e.g., particle mixing, bioirrigation) of abundant macrobenthos play an important role in the year-round biogeochemical processes occurring on this flat.     

The effects of detergents DDM and β-OG on the singlet excited state lifetime of the chlorophyll a in cytochrome b6f complex from spinach chloroplasts

The singlet excited state lifetime of the chlorophyll a (Chi a) in cytochrome b6f (Cyt b6f) complex was reported to be shorter than that of free Chl a in methanol, but the value was different for Cyt b6f complexes from different sources (～200 and ～600 ps are the two measured results). The present study demonstrated that the singiet excited state lifetime is associated with the detergents n-dodecyl-β-D-maltoside (DDM) and n-octyl-β-D-glucopyranoside (β-OG), but has nothing to do with the different sources of Cyt b6f complexes. Compared with the Cyt b6f dissolved in β-OG, the Cyt b6f in DDM had a lower fluorescence yield, a lower photodegradation rate of Chl a, and a shorter lifetime of Chl a excited state. In short, the singlet excited state lifetime, ～200 ps, of the Chl a in Cyt b6f complex in DDM is closer to the true in vivo.     

The effect of non-algal turbidity on the relationship of Secchi depth to chlorophyll a

Data from four reservoirs representative of different trophic states and with different apparent optical properties were analyzed to determine the relationship of Secchi depth to algal biomass as measured by chlorophyll a. In the eutrophic reservoir Secchi depth was determined partially by the chlorophyll a content (r² = 0.31) but only when chlorophyll a data from bloom conditions are included. In the two mesotrophic reservoirs, Secchi depth was entirely determined by non-algal turbidity. In the oligotrophic reservoir, Secchi depth was determined neither by chlorophyll a nor non-algal turbidity and was probably determined by dissolved color. When data from the four reservoirs were pooled (N = 205), 53% of the variation in Secchi depth was explained by: SD = 2.55–0.52 ln (Turbidity) + 0.005 (Chlorophyll a). It is apparent that attempts to estimate algal biomass for trophic state classification or other management practices from Secchi depth data are inappropriate even where moderate amounts of non-algal turbidity are present.     

Study on energy transfer between carotenoid and chlorophyll a in cytochrome b 6 f complex from Bryopsis corticulans

The excitation energy transfer between carotenoid and chlorophyll (Chl) in the cytochrome b ₆ f complex from Bryopsis corticulans (B. corticulans), in which the carotenoid is 9-cis-α-carotene, was investigated by means of fluorescence excitation and sub-microsecond time-resolved absorption spectroscopies. The presence of efficient singlet excitation transfer from α-carotene to Chl a was found with an overall efficiency as high as ∼ ∼24%, meanwhile the Chl a-to-α-carotene triplet excitation transfer was also evidenced. Circular dichroism spectroscopy showed that α-carotene molecule existed in an asymmetric environment and Chl a molecule had a certain orientation in this complex.Bin-Xing Li and Ping Zuo contributed equally to this work.     

The influence of ultraviolet-B radiation on the growth, pigment production and chlorophyll fluorescence of Norway spruce seedlings

Norway spruce (Picea abies (L.)Karst.) from seven seed sources was grown in a greenhouse with 8.3 and 14.7 kJ·m⁻²·d⁻¹ m UV-B_BE (biologically effective UV-B: 280–320 nm) irradiation, and with no supplemental irradiation as control. The seedlings total biomass (dry weight) and shoot growth decreased with high UV-B treatment but spruce from low elevation seed sources were more affected. The seedlings grown at the highest UV-B irradiance (14.7 kJ·m⁻²·d⁻¹) showed from 5 to 38% inhibition of total biomass and 15 to 70 % shoot growth inhibition. Norway spruce populations from higher altitude seed sources manifested greater tolerance to UV-B radiation compared to plants from low altitudes. Changes in phospholipids and protective pigments were also determined. The plants grown at the lower UV-B irradiance (8.3 kJ·m⁻²·d⁻¹) showed greater ability to concentrations UV-B-absorbing pigments then control plants. Chlorophyll a fluorescence parameter R_fd, (R_fd=(F_m-F_s)/F_s) showed a significant decrease in needles of UV-B treated plants and this correlated with the altitude of seed source. Exposure to UV-B affect levels of the ratio of variable to maximum fluorescence (F_v/F_m). Results from this study suggest that the response to increased levels of UV-B radiation is depended upon the ecotypic differentiation of Norway spruce and involved changes in metabolites in plant tissues.