Planktic cyanophytes and their ecology in the shallow Lake Mikri Prespa, Greece

Cyanophytes dominated the phytoplankton of shallow Lake Mikri Prespa during the period May 1990 to September 1992 (76.5 and 52.0% of the total phytoplankton biomass in 1990–1991 and 1991–1992, respectively). Biomass peaks were observed in autumn (from 5.2 to 34.5 g m^-3) when low dissolved inorganic nitrogen, high phosphate phosphorus and low Z_cu to Z_mix ratio prevailed. The dominant species were Microcystis aeruginosa and M. wesenbergii. These represented 64 and 86% of the cyanophyte biomass in 1990–1991 and 1991–1992, respectively and revealed similar patterns of seasonality forming biomass peaks in late summer - autumn. Small chroococcalean cyanophytes (< 2 μm) showed also similar temporal distributions. Of the filamentous cyanophytes, the most important species was Anabaena lemmermannii var. minor which formed peaks in late summer and autumn (2.6 and 1.1 g m^-3 in 1990 and 1992, respectively). Rainfall and the N:P ratio were probably the main factors influencing the seasonality of all of the filamentous cyanophytes in the lake. Cyanophytes, tended to increase at temperatures higher than 16 °C and at inorganic nitrogen concentrations lower than 100 μg 1^--¹. The frequent mixing of the water column did not seem to prohibit the substantial increase of the group.     

Facultative diazotrophy increases Cylindrospermopsis raciborskii competitiveness under fluctuating nitrogen availability

Relative fitness of three bloom-forming and potentially toxic cyanobacteria from the subtropical St. John's River, Florida was investigated under a range of nutrient conditions, during a bloom dominated by Cylindrospermopsis raciborskii. Nitrogen (N) was the primary nutrient limiting phytoplankton primary productivity and biomass. Phytoplankton biomass was also enhanced by phosphorus (P) added either alone or jointly with N, suggesting different components of the phytoplankton experienced distinct nutrient limitations. Based on quantitative PCR, the diazotrophic cyanobacteria Anabaena sp. and C.?raciborskii were responsible for the primary production response to P additions, while the nondiazotrophic Microcystis aeruginosa appeared to benefit from N released from the diazotrophs. Cylindrospermopsis raciborskii maintained high net growth rates under diazotrophic and nondiazotrophic conditions, while Anabaena sp. growth was significantly reduced under DIN enrichment. C.?raciborskii appears to be a generalist with regard to N source, a lifestyle traditionally not considered a viable ecological strategy among diazotrophs. Using facultative diazotrophy, C.?raciborskii gains a growth advantage under fluctuating DIN conditions, such as systems that are under the influence of anthropogenic N loading events. The described niche differentiation may be a key factor explaining the recent global expansion of C.?raciborskii.     

Thermoregulation and metabolism in the Cape golden mole (Insectivora: Chrysochloris asiatica)

The Cape golden mole, Chrysochloris asiatica is an insectivore which excavates superficial foraging burrows as it searches for its food. It has a mean (±S.D.) resting metabolic rate (RMR) when newly captured of 1–17±0.17 cm³ O₂g^-1 h^-1 ( n = 14), within the thermoneutral zone (TNZ) of 30–32°C.
The body temperature (Tb) of the mole in the TNZ is low 32.9 ± 0.36 ( n = 14) and remains stable at ambient temperatures (Tas) from 28–32°C. Above 32°C (range 34–37°C), Tb increases albeit slightly to 36 ± 1.75°C ( n = 14). The conductance is high 0.27 ± 006cm³ O₂g^-1 h^-l°C^-1 ( n = 46) at the lower limit of thermoneutrality. The mean RMR at 9°C (the lowest Ta tested) was 4.82±11 cm³ O₂g^-1h^-1, which is 4.1 times that of the RMR in the TNZ.
At an ambient temperature of 9°C, three of the golden moles entered a state of torpor where the RMR was reduced from 5.9±0.56 to 10 1.0 ± 0.69cm³O₂g^-1h^-1.     

LIGHT-DEPENDENT GROWTH, DARK SURVIVAL, AND GLUCOSE UPTAKE BY CRYPTOPHYTES ISOLATED FROM A FRESHWATER CHEMOCLINE

Clones of Cryptomonas phaseolus Skuja , Cryptomonas rostratiformis ( Skuja ) Skuja in Huber-Pestalozi, and Cryptomonas undulata Gervais were isolated from the deep chlorophyll maximum near the oxic/anoxic boundary layer of the mesoeutrophic lake Schlachtensee, Germany. Different autecological features of these species were studied in batch culture experiments . Cryptomonas cf . ovata Ehrenberg and Chroomonas sp. that never dominated in the deep chlorophyll layer were also isolated from Schlachtensee to study their light-dependent growth in comparison to the deep-living species . Cryptomonas undulata, C. cf . ovata, and C. phaseolus had a very low light compensation point ( 5–7 μmol.m^-2.s^-1 ), whereas the growth rate of Chroomonas sp. and C. rostratiformis was positive above 16 and 24 μmol.m^-2.s^-1 . Cryptomonas phaseclus and Chroomonas sp. became photoinhibited above photon flux densities of 92 and 116 μmol.m^-2.s^-1 . Cryptomonas rostratiformis, C. cf . ovata, and C. undulata reached a maximum growth rate at a considerably higher photon flux density (198–250 μmol.m^-2.s^-1 ). Cryptomonas phaseolus grew fastest under light-limiting conditions . Chyptomonas phaseolus and C. undulata were best able to suruive prolonged periods of darkness . Cryptomonas phaseolus, C. rostratiformis, and C. undulata did not show any uptake of fluorescent latex beads. When labeled glucose was provided in naturally occurring concentrations, carbon uptake by C. phaseolus, C. rostratiformis, and C. undulata was negligibly small in comparison to cellular carbon content. I suggest that the adaptation to a low-light environment is an important preadaptation for the dominance of C. phaseolus and C. undulata near the freshwater chemocline .     

Growth, diet and metabolism of common wolf–fish in the North Sea, a fast–growing population

The von Bertalanffy growth parameters for common wolf–fish Anarhichas lupus in the North Sea were: male: L ∞=111·2 cm, t ₀=–0·43 and K =0·12; and female: L ∞=115·1 cm, t ₀=–0·39 and K =0·11, making this the fastest growing stock reported. Resting metabolic rates (RMR±S.E.) and maximum metabolic rates (MMR±S.E.) for six adult common wolf–fish (mean weight, 1·39 kg) at 5° C were 12·18±1·6 mg O₂ kg^–1 h^–1 and 70·65±7·63 mg O₂ kg^–1 h^–1 respectively, and at 10° C were 25·43±1·31 mg O₂ kg^–1 h^–1 and 113·84±16·26 mg O₂ kg^–1 h^–1. Absolute metabolic scope was 53% greater at 10° C than at 5° C. The diet was dominated by Decapoda (39% overall by relative occurrence), Bivalvia (20%) and Gastropoda (12%). Sea urchins, typically of low energy value, occupied only 7% of the diet. The fast growth probably resulted from summer temperatures approximating to the optimum for food processing and growth, but may have been influenced by diet, and reduced competition following high fishing intensity.     

Cryptic speciation in the cosmopolitan <Emphasis Type="Italic">Epiphanes senta</Emphasis> complex (Monogononta,Rotifera) with the description of new species

The phytoplankton species composition and seasonal succession were examined in Lake Kastoria during the period November 1998–October 1999. A total of 67 species and 19 functional groups were identified. Only 4 out of the 67 species, all Cyanobacteria, were dominant (Limnothrix redekei, Microcystis aeruginosa, Cylindrospermopsis raciborskii and Aphanizomenon gracile). Diatoms were rare, not only in terms of species number, but also in terms of biomass (contributing <5% to the total phytoplankton biomass) in relation to the rather low silicon concentrations throughout the year. The functional groups S1, S_N, M and H1 were found dominant in the lake. The species A. gracile (functional group H1) behaved like the species Cylindrospermopsis raciborskii (functional group S_N) which is tolerant to mixing and poor light conditions. The phytoplankton seasonal succession showed similar patterns in all six sampling stations, both at the surface and the bottom water layer, with minor differences during Microcystis aeruginosa dominance. Two steady-state phases were identified within a year lasting for 4 months under relatively stable physical conditions. In these steady-states, the Limnothrix redekei persistent dominance under low light availability and low inorganic nitrogen has been explained by its specific ability such as buoyancy regulation to exploit resources in the water column. Moreover, high population densities over the winter and before the development of daphnids may contribute to the steady-state dominance of Limnothrix. Different niches separated vertically in the water column is one of the explanations for the Limnothrix–Microcystis steady-state when a replacement between the two species was observed in different water layers and areas of the lake. Long lasting steady-states of Cyanobacteria observed in Lake Kastoria and in other Mediterranean and tropical freshwaters may indicate influence of warm climate properties on phytoplankton dynamics. Electronic Supplementary Material Supplementary material is available to authorized users in the online version of this article at http://dx.doi.org/10.1007/s10750-006-0360-4 Handling editor: K. Martens     

EFFECT OF DISSOLVED OXYGEN PARTIAL PRESSURE ON THE ACCUMULATION OF ASTAXANTHIN IN CHEMOSTAT CULTURES OF HAEMATOCOCCUS LACUSTRIS (CHLOROPHYTA)

The effect of dissolved oxygen partial pressure on the accumulation of astaxanthin in the green alga Haematococcus lacustris ( Gir.) Rostaf (UTEX16) was studied in N-limited continuous chemostat cultures. The steady-state astaxanthin content measured against culture volume, cell number, and biomass dry weigh of Haematococcus cultures was proportional to the dissolved O₂ partial pressure in the culture medium, over the range of 0–50% O₂ The steady-state biomass dry weight concentrations remained at between 0.52 and 0.57 g. L^-1 over the range of dissolved O₂ partial pressure studied. Steady-state cell densities at dissolved O₂ partial pressures above the air saturation level (1.13–1.58 × 10⁵ cells.mL^-1) were about half of that measured at lower dissolved O₂ partial pressures (2.42–2.63 × 10⁵ cells.mL^-1). Both biflagellated zoospores and nonmotile aplanospores were found at steady state. The fraction of nonmotile cells was higher at dissolved O₂ partial pressures above the air saturation level (94.44–98.01%) than at dissolved O₂ partial pressure below the air level (79.64–86.12 and 91.75% ).     

Life cycle and population dynamics of Trochosa terricola Thorell (Araneae: Lycosidae) in a Norfolk grass heath

Abstract. 1. The population of the lycosid Trochosa terricola Thorell was sampled from April 1973 to August 1975 at Weeting Heath NNR, a Breckland grass heath.
2. Four sampling methods were compared for efficiency. Hand searching gave density estimates between 38.3 and 70.1% of heat extraction.
3. The temperature range in the sward at +1 cm was –5°C to 39°C with January and July means of 3.2°C and 17.4°C.
4. Eight male and nine female instars were determined and the life cycle extended over 2 or 3 years.
5. Adults were nocturnal but the juveniles diurnal. An annual diplochrone activity pattern was observed for adult males.
6. The horizontal distribution within the sward was aggregated, the structure and microhabitat being important determining factors. The population density was greater in moist, young Festuca spp. tussocks. An equation relating population density to habitat characteristics was derived.
7. The overall population density ranged from 14.0 m^-2 to 76.0 m^-2 and was maximal in autumn after breeding. The population biomass was greatest during autumn (291.2 mg d.wt m^-2).
8. Mean number of juveniles emerging from an egg sac was 77.3 (first sac) and 38.0 (second sac). The natality in 1973 was 66.8 individuals m^-2.
9. The survivorship curve until maturity varied between types I and III in different years.
10. The population dynamics were compared and are discussed in the light of other data. The variable population characteristics suggested that Den Boer's "spreading of risk" theory applied to the T.terricola population.     

Oxygen consumption in Oreochromis niloticus (L.) in relation to development, salinity, temperature and time of day

Oxygen consumption of Oreochromis niloticus at different stages of development was studied in relation to salinity, temperature and time of day, using a Warburg apparatus. The oxygen consumption of newly hatched (0–14 h) larvae was 3.40 μl O₂ larva⁻¹ h⁻¹, of older yolk sac larvae 10.09 μl O₂ larva⁻¹ h⁻¹, and of one-month-old fry 32.99 μl O₂ larva⁻¹ h⁻¹. The QO₂ values showed a decrease with development and growth, ranging from 21.2–26.0 μl O₂ mg⁻¹ h⁻¹ in newly hatched larvae to 2.97 μl mg⁻¹ h⁻¹ in one-month-old fry. Changes in oxygen consumption occurred with salinity, the highest being at 17%o. Active larvae (12-24 mm T.L.) showed a doubling of consumption with a 10° C rise in temperature, and their Q₁₀ factor increased from 2.25 to 3.43 with increasing size. Day-old yolk-sac larvae, late yolk-sac larvae (5 days old) and fry of 12 14 mm length all showed a depression in oxygen consumption at midnight followed by a dawn rise.     

Energetics of a population of Asellus aquaticus (Crustacea, Isopoda): respiration and energy budgets

SUMMARY. Respiration of Asellus aquaticus was determined on tiine occasions throughout the year using a Gilson differential respirometer. On each occasion the determination was made at the lake temperature, which ranged from 2 to 18°C, Linear regressions were derived for log oxygen uptake against log dry weight. There was a significant difference between mean rates of oxygen uptake at the various temperatures but the slopes of the regression lines, which varied from 0,62 to O.85 with a mean of 0,76, were not significantly different.
The temperature of the lake was monitored throughout the year. Using the relationship of oxygen uptake against temperature, and estimates of population density obtained previously, the total annual respiration of the population was calculated as 4571 ml O₂ m^-2, equivalent to an energy loss of 92.3 kj m^-2 year^-1 from a mean biomassof 752 mg m^-2.
Consumption of decayed Alnus glutinosa leaves and faecal production rates, and thus assimilation efficiency, were determined by gravimetric methods in the laboratory at 10°C, close to the mean temperature of the lake (10.rC), In the four size classes investigated, larger animals consumed more food per individual, but less on a weight specific basis. However, it was shown that consumption was greater if the leaf material was more highly decomposed, Assimiliation efficiency was calculated as 23%.
Using data for respiration, population density and the assimilation efficiency, the annual population energy budget was estimated as (kJ m^-2year^-1): consumption, 568.9 (100%); production, 38.5 (6.8%); respiration, 92.3 (16.2%); faeces, 438.1 (77%). The significance of these energy values, and the ecological efficiencies calculated from them, are discussed in relation to other published work.     

Scaling of oxygen consumption of Lake Magadi tilapia, a fish living at 37°C

Rates of oxygen consumption were measured in the geothermal, hot spring fish, Oreochromis alcalicus grahami by stopped flow respirometry. At 37° C, routine oxygen consumption followed the allometric relationship: V o₂=0.738 M ^0.75, where V o₂ is ml O₂ h ⁻¹ and M is body mass (g). This represents a routine metabolic rate for a 10 g fish at 37° C of 0.415 ml O₂ g⁻¹ h ⁻¹ (16.4 μmol O₂ g ⁻¹ h ⁻¹). Acutely increasing the temperature from 37 to 42° C significantly elevated the rate of O₂ consumption from 0.739 to 0.970 ml O₂ g ⁻¹ h ⁻¹ ( Q ₁₀=l.72). In the field, O. a. grahami was observed to be 'gulping' air from the surface of the water especially in hot springs that exceeded 40° C. O. a. grahami may utilize aerial respiration when O₂ requirements are high.     

Seasonal differences in routine oxygen consumption rates of the bonnethead shark

Routine oxygen consumption rates of bonnethead sharks, Sphyrna tiburo , increased from 141·3±29·7 mg O₂ kg⁻¹ h⁻¹ during autumn to 218·6±64·2 mg O₂ kg⁻¹ h⁻¹ during spring, and 329·7±38·3 mg O₂ kg⁻¹ h⁻¹ during summer. The rate of routine oxygen consumption increased over the entire seasonal temperature range (20–30° C) at a Q ₁₀=2·34.     

INTRACELLULAR CYANOBACTERIAL SYMBIONTS IN THE MARINE DIATOM CLIMACODIUM FRAUENFELDIANUM (BACILLARIOPHYCEAE)

The diatom Climacodium frauenfeldianum Grunow was collected in the tropical Atlantic and Pacific Oceans. Observations with epifluorescence microscopy revealed that this diatom contained coccoid symbionts (2.5–3.5 μm) with a typical cyanobacterial fluorescence in addition to that of their own chloroplasts. Mean concentration of C. frauenfeldianum for 28 stations in the SW tropical Pacific Ocean was 530 x 10³ (SE = 1372) cells·m ^{− 2}, with highest concentration (mean 17.5 cells·L ^{− 1}) at 40-m depth. The symbiosis was only observed at water temperatures between 26.3 and 28.9° C, with highest concentrations at 27.7° C. Three almost complete 16S rDNA sequences from one sample were determined, and they were identical. The phylogenetic analysis of this 16S rDNA sequence and those from other cyanobacteria and plastids revealed that it was closely related to the 16S rDNA sequence from Cyanothece sp. ATCC 51142. Cyanothece sp. ATCC 51142 is a unicellular nitrogen-fixing cyanobacterium isolated from a coastal marine environment and has ultrastructural features similar to the symbionts of C. frauenfeldianum . The close relationship between Cyanothece sp. and the cyanobacterial symbiont in C. frauenfeldianum suggests the potential for nitrogen fixation in the symbiosis.     

Effects of development, temperature and salinity on metabolism in eggs and yolk-sac larvae of milkfish, Chanos chanos (Forsskål)

Oxygen uptake rates and yolk-inclusive dry weiGhts were measured during the egg and yolk-sac larval stages of milkfish, Chanos chanos (Forsskal). Oxygen uptake by eggs and yolk-sac larvae was measured to assess the effects of four salinities (20,25,30,35 ppt) at 28°C. The effects of three temperatures (23,28,33°C) on oxygen uptake by yolk-sac larvae were determined at a salinity of 35 ppt. Dry weights were measured throughout embryonic development at 28°C and the yolk-sac stage at 23.28 and 33°C.
Oxygen uptake rates of eggs increased more than fivefold during embryogenesis (0.07±0.03 to 0.40 ± 03 μl O₂ egg ⁻¹ h ⁻¹;blastula to prehatch stage). Larval oxygen uptake did not change with age but was affected by rearing temperature (0.33 ± 0.08, 0.44 ± 0.07 and 0.63 ± 0.13 μl O₂ larva ⁻¹ h⁻¹ at 23, 28 and 33°C, respectively; Q₁₀= 1.93). Acute temperature changes from 28 to 33°C caused significant increases in oxygen uptake by embryos (Q ₁₀= 1.69–3.58) and yolk-sac larvae (Q ₁₀=2.55). Salinity did not affect metabolic rates.
Dry weight of eggs incubated at 28°C decreased 13% from fertilization to hatching. Incubation temperatures from 23–33°C did not affect dry weights at hatching. Rearing temperatures significantly affected the rate of larval yolk absorption (Q ₁₀= 2.25).     

The growth rate of eel in tributaries of the lower River Severn, England, and its relationship with stock size

The growth rate of 1980 eel Anguilla anguilla from 15 sites in the Severn system varied between 16·4 and 27·9 mm year^-1, density from 0·12 to 1·14 m^-2 and biomass from 2·56 to 25·24 g m^-2. There was no significant relationship between growth rate and density or biomass ( P > 0·05).     

Hydrogen uptake in Anabaena sp. strain CA does not protect nitrogenase from inactivation by hyperbaric oxygen

Abstract Two mutants of Anabaena sp. strain CA were used to demonstrate that oxygen-dependent hydrogen uptake was not the primary means to protect the nitrogenase enzyme complex from the deleterious effects of hyperbaric oxygen in vivo. Exposure to air caused the immediate and irreversible inactivation of nitrogenase activity in an oxygen-sensitive mutant, designated strain 22Y. Inactivation was concomitant with the destruction of the molybdo-iron (MoFe) protein of the nitrogenase complex. The mutant 22Y expressed an O₂-stable, Ni²⁺-stimulated hydrogen uptake of up to 2.7 μM H₂ per mg dry wt per h. Conversely, after exposure to 1% CO₂-99% O₂ for 3 h, both wild-type strain CA and a hydrogen uptake deficient (Hup⁻) mutant, strain N9AR, recovered 70–80% of their original acetylene reduction capacity with no apparent perturbations in the MoFe protein.     

NEW GENERA OF FRESHWATER CRYPTOMONADS FROM COLORADO

Given their rapid growth and nutrient assimilation rates, Porphyra spp. are good candidates for bioremediation. The production potential of two northeast U.S. Porphyra species currently in culture ( P. purpurea and P. umbilicalis ) was evaluated by measuring rates of photosynthesis (as O₂ evolution) of samples grown at 20° C. Gametophytes of P. umbilicalis photosynthesized at rates that were 80% higher than those of P. purpurea over 5–20° C at both sub-saturating and saturating irradiances (37 and 289 μmol photons m⁻² s⁻¹). Porphyra umbilicalis was both more efficient at low irradiances (higher alpha) and had a higher P_max than did P. purpurea (23.0 vs. 15.6 μmol O₂ g⁻¹ DW min⁻¹), suggesting that P. umbilicalis is a better choice for mass culture where self-shading may be severe. The photosynthesis-irradiance relationship for the Conchocelis stage of P. purpurea was also examined. Tufts of filaments, grown at 10, 15, and 20° C, were assayed at growth temperatures at irradiances ranging from 0–315 μmol photons m⁻² s⁻¹. Tufts were slightly more productive at 15° than at 10° C, but only ca. 4–6% as productive as gametophytes. Maximum rates of net photosynthesis were reduced by 66–74% in tufts grown at 20° C (only about 2% of gametophytes). The Conchocelis stage, however, need not limit mariculture operations; once Conchocelis cultures are established, they can be maintained over the long-term as ready sources of spores for net seeding.     

Seasonal changes in biom ass of macrophytes on shaded and unshaded sections of the River Lambourn, England

SUMMARY. Monthly changes in the biomass of Ranunculus, Berula and Callitriche were recorded on two 50-m sites on the River Lambourn at Bagnor between March 1971 and October 1973. On the unshaded site. Ranunculus was the dominant macrophyte and characteristically its biomass changed from 20–40 g dry wt m^-2 in March to around 400 g dry wt m^-2 at the end of the growing season. On the shaded site, where Berula was the dominant macrophyte. the biomass of Ranunculus was lower than on the unshaded site. There was no significant difference between the mean biomasses of Berula on these two sites but Callitriche had a signifieantly higher biomass on the shaded site. Estimates of the total biomass of macrophyte on each site were calculated and the biomass of macrophyte removed during cutting operations each summer was also assessed.     

Mode of interference of chlorosis-inducing herbicides with peroxisomal enzyme activities

In rye leaves ( Secale cereale L. cv. Petkus "Kustro") bleached in the presence of the chlorosis-inducing herbicides aminotriazole, haloxidine, San 6706 or difunone in white light of 54.2 W m^-2 (5000 lx), catalase activity was very low. In addition, the activities of glycolate oxidase and hydroxypyruvate reductase were strongly diminished in treatments with San 6706 and difunone. The lowering of the peroxisomal enzyme activities was observed in red, but not in blue light and did not occur after treatment with the non-bleaching pyridazinone derivative San 9785. The deficiencies of the peroxisomal enzymes did not appear to be involved in the initiation of the chlorosis. Instead they are probably produced as secondary consequences of the bleaching. Low peroxisomal enzyme activities were also obtained without herbicide treatment by growing the leaves in an atmosphere of 2% O₂ and 3% CO₂, but in this case were not accompanied by an increased sensitivity of the Chl to photooxidative bleaching. The peroxisomal enzymes reached as high activities as in untreated controls when the herbicide-treated leaves were grown at a low light intensity of 0.106 W m^-2 (10 lx). After transfer of herbicide-treated leaves grown under 0.106 W m^-2 to 306 W m^-2 (30 000 lx), catalase was strongly inactivated, even at 0°C. In treatments with San 6706 and difunone the increase of the activities of glycolate oxidase and hydroxypyruvate reductase was either stopped, remaining unchanged, or the enzymes were slightly inactivated after exposure to 306 W m^-2 (30 000 lx). The observations suggest that the inactivation of peroxisomal enzymes results from photooxidative events in the chloroplasts.     

Biomass, reproductive output, and physiological responses of rapid-cycling Brassica (Brassica rapa) to ozone and modified root temperature

Brassica rapa L. (rapid-cycling Brassica), was grown in environmentally controlled chambers to determine the interactive effects of ozone (O₃) and increased root temperature (RT) on biomass, reproductive output, and photosynthesis. Plants were grown with or without an average treatment of 63 ppb O₃. RT treatments were 13°C (LRT) and 18°C (HRT). Air temperatures were 25°C/15°C day/night for all RT treatments.
Ozone affected plant biomass more than did root temperature. Plants in O₃ had significantly smaller total plant d. wt, shoot weight, leaf weight, leaf area and leaf number than plants grown without O₃. LRT plants tended to have slightly smaller total plant d. wt, shoot weight, root weight, leaf weight, leaf area, and leaf number than HRT plants. For all variables, LRT plants grown in O₃ had the smallest biomass, and plants grown in HRT without O₃ had the largest biomass.
Ozone reduced both fruit weight and fruit number; LRT also reduced fruit weight but had no effect on fruit number. Ozone reduced photosynthesis but RT had no effect. Conductance and internal CO₂ were unaffected by O₃ or RT.
These studies indicate that plant growth with LRT might be more reduced in the presence of O₃ than growth in plants with HRT, which might be able to compensate for O₃-caused reductions in photosynthesis to avoid decreased biomass and reproductive output.