Adaptation to an acid environment in Chironomus riparius (Diptera, Chironomidae) from Smoking Hills, NWT, Canada

The Smoking Hills in the North West Territories, Canada have burnt for centuries causing long term acidification of ponds in the vicinity. Chironomus riparius , a red chironomid larva dominated the bottom fauna in the ponds. It was investigated if it was the buffering capacity of the hemolymph rather than the oxygen binding capacity of its hemoglobin that gave these larvae a selective advantage and explained their high abundance. Canadian C. riparius larvae were compared with larvae of the same species from Sweden and with larvae of Chironomus plumosus and C. anthracinus also from Sweden. The Canadian strain of C. riparius survived 7 d exposure to pH 3.5 much better than the others. Titration curves on the hemolymph showed that the Canadian larvae had the highest buffering capacity. Within the pH range 6.0–7.0 it was 17–18 meq pH⁻¹ 1⁻¹ as compared with 13–15 meq pH⁻¹ 1⁻¹ for the others. The hemoglobin content of the Canadian larvae was found to be twice as high as that of the same species from Sweden.     

The fauna of the muddy sediments of Lough Neagh, with particular reference to eutrophication

SUMMARY. The main groups of animals found in the muddy sediments of Lough Neagh were Chironomidae (Diptera) and Oligochaeta (mainly Tubificidae). At 8 m depth, the average biomass of the main species in these groups was: Chironomus anthracinus , 2.64gm⁻²; Procladius , 342.8 mgm⁻²; tubificids ( Tubifex, Potamothrix, Aulodrilus, Limnodrilus ), 418.7mgm⁻². At 25m depth C. anthracinus and Procladius were less abundant, C. plumosus was present and among the tubificids Limnodrilus had a higher density (up to 50000m⁻²) often an order of magnitude greater than at 8m. Kinnego Bay, a semi-enclosed, polluted area of the lough, had fewer chironomids than the open lough, with chiefly C. plumosus and Procladius. Limnodrilus was more abundant than at 8m. Dero obtusa (Naididae) was also present, sometimes in large numbers (31000m⁻²).
The response of this fauna to eutrophication in L. Neagh appears to be a diminution in the number of species present, with C. plumosus gradually replacing C. anthracinus as the dominant Chironomus , and tubificids, particularly Limnodrilus , becoming more abundant, A further stage, shown in Kinnego Bay, has Procladius as the most numerous' chironomid. Average total biomass at the three sites was 3.9gm⁻² at 8m, 13.2gm⁻² at 25 m in the main lake, 2.8gm⁻² in Kinnego Bay. At 8m depth, C. anthracinus contributed 76% of the total biomass, at 25m Limnodrilus contributed 74% and C. anthracinus 15%, and in Kinnego Bay, Limnodrilus contributed 40%, C. plumosus 28% and Procladius 20%.     

Seasonal variation in diet of Chironomus plumosus (L.) and C. anthracinus Zett. (Diptera: Chironomidae) in mesotrophic Lake Erken

SUMMARY. 1. Microscopic gut content analysis of Chironomus plumosus (L.) and C. anthracinus Zett. collected from 18m depth in mesotrophic Lake Erken. revealed significant seasonal differences between the two species.
2. C. plumosus dietary constituents showed greater seasonal variation than those of C. anthracinus , with diatom contribution to the gut contents reflecting temporal changes in the phytoplankton.
3. Overall the percentage of gut content constituted by detritus, algae, animal remains, and inorganic matter averaged 96%, 4%, 0.4% and 0.03% for C. plurnosus and 97%, 3%, 0.6% and 0.03% for C. anthracinus .
4. Coefficients ot dietary overlap for non-detrital foods decreased markedly from August to September. During this period the proportion of centric diatoms in the guts of C. plumosus increased by 94% while no marked changes were noted in C. anthracinus .
5. C. ptttmosus ingested more diatoms than C. anthracinus , especially during diatom blooms in spring and autumn. These results are consistent with the known differences in feeding behaviour between these two speeies.     

Suppression of reactive oxygen species production enhances neuronal survival in vitro and in vivo in the anoxia-tolerant turtle Trachemys scripta

Hypoxia-ischemia with reperfusion is known to cause reactive oxygen species-related damage in mammalian systems, yet, the anoxia tolerant freshwater turtle is able to survive repeated bouts of anoxia/reoxygenation without apparent damage. Although the physiology of anoxia tolerance has been much studied, the adaptations that permit survival of reoxygenation stress have been largely ignored. In this study, we examine ROS production in the turtle striatum and in primary neuronal cultures, and examine the effects of adenosine (AD) on cell survival and ROS. Hydroxyl radical formation was measured by the conversion of salicylate to 2,3-dihydroxybenzoic acid (2,3-DHBA) using microdialysis; reoxygenation after 1 or 4 h anoxia did not result in increased ROS production compared with basal normoxic levels, nor did H₂O₂ increase after anoxia/reoxygenation in neuronally enriched cell cultures. Blockade of AD receptors increased both ROS production and cell death in vitro , while AD agonists decreased cell death and ROS. As turtle neurons proved surprisingly susceptible to externally imposed ROS stress (H₂O₂), we propose that the suppression of ROS formation, coupled to high antioxidant levels, is necessary for reoxygenation survival. As an evolutionarily selected adaptation, the ability to suppress ROS formation could prove an interesting path to investigate new therapeutic targets in mammals.     

About the possibility of hybridogenesis in the species origin of the midge Chironomus usenicus Loginova et Beljanina (Chironomidae,Diptera)

Hybridogenesis as a possible way of speciation in Chironomidae was considered with special reference to the species Chironomus usenicus resulting from hybridization between C. plumosus and C. behningi. The three species had 2n = 8 and belonged to the thummi cytocomplex with chromosome arm combinations AB, CD, EF, and G. Arm G had a marker chromosome disk sequence (CDS) and was used to demonstrate the hybrid origin of C. usenicus. Most C. usenicus larvae were heterozygous in CDS of arm G. CDS use G2 proved to be identical to CDS beh G1 of C. behningi and CDS use G1, to CDS plu G1 of C. plumosus. It was assumed that C. usenicus results from hybridization between eurybiont C. plumosus and stenobiont C. behnigni at the boundary of their species areas, in freshwater or brackish water bodies of the southern Saratov oblast and northern Kazakhstan. Morphologically and karyotypically, the hybrid was probably similar to C. plumosus. Crosses with C. plumosus eliminated virtually all C. behningi chromosome sequences from the karyotype of the hybrid. Further chromosome divergence resulting in C. usenicus involved a number of chromosome rearrangements, including duplication of pericentric heterochromatin and other chromosome regions; inversion, which occurred in arm F (regions 13-16) and was fixed in the karyotype; and other paracentric inversions and deletions accumulated in heterozygote in the karyotype pool of the species. Since C. behningi was eliminated from the introgression zone and its species are reduced, the assimilation character was assumed for introgressive hybridization of C. behningi and C. plumosus.     

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).     

Colonization of Vibrio pelagius and Aeromonas caviae in early developing turbot (Scophthalmus maximus L.) larvae

Polyclonal antisera made in rabbits against whole washed cells of Vibrio pelagius and Aeromonas caviae were used for detection of these bacterial species in the rearing water and gastrointestinal tract of healthy turbot ( Scophthalmus maximus ) larvae exposed to V. pelagius and/or Aer. caviae . The results demonstrated that this method is suitable for detection of V. pelagius and Aer. caviae in water samples and larvae at population levels higher than 10³ ml⁻¹ and 10³ larva⁻¹. Populations of aerobic heterotrophic bacteria present in the gastrointestinal tract of turbot larvae, estimated using the dilution plate technique, increased from approximately 4 × 10² bacteria larva⁻¹ on day 3 post-hatching to approximately 10⁵ bacteria fish⁻¹ 16 days post-hatching. Sixteen days after hatching, Vibrio spp. accounted for approximately 3 × 10⁴ cfu larva⁻¹ exposed to V. pelagius on days 2, 5 and 8 post-hatching. However, only 10³ of the Vibrio spp. belonged to V. pelagius . When larvae were exposed to Aer. caviae on day 2 post-hatching, the gut microbiota of 5-day old larvae was mainly colonized by Aeromonas spp. (10⁴ larva⁻¹), of which 9 × 10³ belonged to Aer. caviae . Later in the experiment, at the time when high mortality occurred, 9 × 10⁵ Aer. caviae were detected. Introduction of V. pelagius to the rearing water seemed to improve larval survival compared with fish exposed to Aer. caviae and with the control group. It was therefore concluded that it is beneficial with regard to larval survival to introduce bacteria ( V. pelagius ) to the rearing water.     

Oxygen consumption by eggs and larvae of striped mullet, Mugil cephalus, in relation to development, salinity and temperature

Oxygen consumption rates during embryonic and the first 38 days of larval development of the striped mullet were measured at 24° C by differential respirometry. Measurements were obtained at the blastula, gastrula and four embryonic stages, and at the yolk-sac, preflexion, flexion and post-flexion larval stages.
Oxygen uptake rates of eggs increased linearly from 0.024 μl O₂ per egg h^-1 (0·323 μl O₂ mg^-1 dry wt h^-1) by blastulae to 0·177 μlO₂ per egg h^-1 (2·516 μlO₂mg ¹dry wth^-1) by embryos prior to hatching. Respiration rates did not vary significantly among four salinities (20,25, 30, 35%₀).
Larval oxygen consumption increased in a curvilinear manner from 0·243 μl O₂ per larva h^-1 shortly after hatching to 18·880 μl O₂ per larva h^-1 on day 38. Oxygen consumption varied in direct proportion to dry weight. Mass-specific oxygen consumption rates of preflexion, flexion, and postflexion larvae did not change with age (10·838 μl O₂ mg ¹dry wt h^-1).
Larval oxygen consumption rates did not vary significantly among salinities 10–35%. Acute temperature increases elicited significant increases in oxygen consumption, these being relatively greater in yolk-sac larvae ( Q₁₀ = 2·75) than in postflexion larvae ( Q₁₀ = 1·40).     

Toxic effects of zinc on fathead minnows Pimephales promelas in soft water

A fathead minnow life-cycle exposure to various zinc concentrations demonstrated that the most sensitive indicators of zinc toxicity were egg adhesiveness and fragility, which were significantly affected at 145 μg Zn 1⁻¹ and above, but were not affected at 78 μg Zn 1⁻¹ and below. These effects occurred shortly after the eggs were spawned (during water hardening) and therefore were not related to effects on the parental fish. Hatchability and survival of larvae were significantly reduced, and deformities at hatching were significantly increased at 295 ug Zn 1⁻¹ and above. Acclimated and unacclimated groups of larvae exposed to identical zinc concentrations for 8 weeks after hatch showed only slight differences in sensitivity.     

Oxygen requirements of larvae of the smallmouth bass, Micropterus dolomieui Lacépède

Smallmouth bass larvae became highly sensitive to oxygen deficiency on the second day after hatching and continued so to the 10th day. During this period they could not survive exposure to 1 mg O₂ l^–1 for 3 h at 20° C, and many were killed within 1 h. At 2 mg O₂ l^–1 half the larvae survived 3 h at 20° C; at 2.5 mg l^–1 most survived, and at 3.5 mg l^–1 all survived. Resistance to oxygen deficiency was regained by the 11th day, the majority of the larvae withstanding a 3-h exposure at 1 mg O₂ l^–1. At 25° C the effects of low oxygen concentration were intensified. At 3 and 4 mg O₂ l^–1 and 20° C the normally quiescent larvae became very active, even swimming to the surface 5 or 6 cm above the substrate. Increasing the temperature increased this response. Smallmouth larvae were more sensitive than large-mouth bass larvae to oxygen deficiency.     

Effects of prey density and short term food deprivation on the growth and survival of American shad larvae

Growth and survival of 16-and 18-day-old American larvae ( Alosa sapidissima ) increased with prey density (0, 500, and 1000 Artemia l⁻¹), though differences were not always significant. Significant differences were not observed in growth parameters and survival for larvae fed 500 v . 1000 Artemia 1⁻¹ in laboratory experiments. Food deprivation for as little as 2 days had significant effects on survival but growth effects were not detectable until 4 days of starvation. These findings have application to the Susquehanna River where c . 11 million 2.5-week-old shad larvae are released annually as part of a basin wide effort to restore the species. Larvae released at upriver sites where food may be limiting would drift for 2–3 days to reach reservoirs with higher prey densities. Based on these laboratory findings, survival of shad may be reduced significantly if larvae do not feed prior to reaching reservoir environments.     

Mechanisms underlying the stable co-existence of two genetically distinct populations of Chironomus plumosus (Diptera: Chironomidae) in Lake Tystrup-Bavelse, Denmark

During April–December in 1980 and 1981 larvae and pupae of Chironomus plumosus from Lake Tystrup-Bavelse, Denmark, were sampled with short intervals On the basis of morphometric data of the larvae, counts of larvae and pupae, and measurements of the oxygen conditions in the lake it was concluded that adults emerge at different times depending on e.g. depth-conditions. Adults originating from the deep Lake Tystrup appear over two periods yearly (April-June) and (September-October). In the intervening period which is characterized by stagnation and shortage of oxygen there is no emergence of adults. Adults from the shallow Lake Bavelse appear mainly during June-August. This shallow lake-part has no, or at the most very short, periods with stagnation and lack of oxygen. The observed temporal difference in the emergence of adults in the two lake-parts is proposed to be the main reason for the maintenance of two different Mendelian populations of Chironomus plumosus in Lake Tystrup-Bavelse.     

Effects of oxygen deficiency on survival and glycogen content of Chironomus anthracinus (Diptera,Chironomidae) under laboratory and field conditions

Growth and glycogen content of Chironomus anthracinus in Lake Esrom, Denmark was examined during summer stratification in 1992 and 1993. Simultaneously, effects of oxygen deficiency on glycogen utilization and survival were experimentally studied. The population consisted of almost fullgrown 4th instar larvae in 1992 and 2nd and 3rd instar larvae in 1993. Growth rate and glycogen content changed as hypolimnetic oxygen deficiency increased. During a 1st phase of stratification dry weight and glycogen content increased (2nd and 3rd instars) or was almost constant (4th instar) but decreased significantly during the following 2nd phase. This change from growth to degrowth and utilization of endogenous glycogen reserves correlated with a change in the thickness of the microxic layer (<0.2 mg O₂ 1^–1) above the sediment surface. The layer increased from 2–3 m in phase 1 to 4–5 m in phase 2, and we suggest that this deteriorated the oxygen conditions and resulted in a change in larval energy metabolism from fully aerobic during the 1st phase to partly anaerobic in the 2nd phase. During the 2nd phase larval metabolism was estimated at less than 20% of normoxic rate. Experimental exposure of the larvae to anoxia indicated highly different survival of young larvae (2nd and 3rd instars) and older larvae (large 4th instars). The morality of young larvae was 50% after three days in anoxia at 10 °C, whereas only 25% of the older larvae had died after 3–4 weeks under similar conditions. Extending the treatment, however, resulted in increased death rate of the 4th instar larvae with only 10% surviving after seven weeks. The anaerobic metabolism of 4th instar larvae as estimated from glycogen degradation at 10 °C was 5% of normoxia in the interval from 0–5 days but 1.5% in the interval from 20–25 days. It is concluded that survival of C. anthracinus in anoxia is very limited, but traces of oxygen in the environment allowing for faint aerobic metabolism prolong the survival time of the larvae from a few days (2nd and 3rd instars) or a few weeks (4th instar) to probably 3–4 months.     

Comparison of the effect of natural and experimental anoxia on carbohydrate and energy metabolism in Iris pseudacorus rhizomes

Carbohydrate utilization in Iris pseudacorus rhizomes was investigated under natural conditions in the field for a period of one year. The area of study was under flood from mid-December to end of May and wet for the rest of the period of study. Rhizome samples were collected in the wild twice monthly. in order to determine glucose content and amount of reducing and non-reducing sugars in the rhizome core material. For comparison with experimental anoxia, rhizomes were washed and kept under strict anoxia in the dark at +20°C. Carbohydrates were measured in groups as above. The amount of ethanol and the levels, of ATP. ADP and AMP were also measured and adenylate energy charge computed.
Glucose content of the rhizomes was 10 mg g⁻¹ fresh weight in the autumn and decreased during winter to reach ca 5 mg g⁻¹ fresh weight in the spring. Total reducing sugars increased in w inter while the amount of non-reducing sugars increased during early autumn and decreased during winter and spring. Not all non-reducing sugar stores had been used up in the spring when growth was resumed. Under experimental anoxia adenylate energy charge remained relatively high for 30 days (near 0.6 or over) and then dropped quickly to bekm 0.3. indicating death of the tissues. After 30 days under anoxia the amount of ethanol still increased and that of total reducing sugars decreased. The level of non-reducing sugars decreased from 0 to 15 days of anoxia before an increase took place durine the next 20 days.     

Karyofund of Chironomus plumosus (Diptera, Chronomidae) in the Palearctic region

Quantitative and qualitative analyses of chromosomal polymorphism in 38 Palearctic populations of Chironomus plumosus were made. It was shown that most of the populations studied were highly polymorphic: in average 63.2 +/- 4.0% of larvae were heterozygous for inversions with 0.95 + 0.08 heterozygous inversion per larvae. Polymorphism on the size of centromeric heterochromatin and the presence of B-chromosomes were observed in many populations studied. The karyofund of Ch. plumosus in Palearctic was estimated. In total 35 banding sequences were found in Palearctic Ch. plumosus. Fifteen banding seguences have been described for the first time. On mapping the used banding sequences, we employed the conventions of Keyl (Keyl, 1962; Devai et al., 1989) and Maximova (Maximova, 1976; Shobanov, 1994a) for arms A, C, D, E and F, and the conventions of Maximova for arms B and G.     

Effects of oxygen level on metabolism and development of seedlings of Trapa natans and two ecologically related species

Seeds of the water plant Trapa natans L. (water chestnut) can germinate in strict anoxia. The seedlings show seminal roots growing upwards while shoot buds remain quiescent until O₂ becomes available. Trapa seedlings are highly tolerant to anoxia. The rate of ethanol fermentation was 21.2 μmol (g FW)⁻¹ h⁻¹, while production of lactate was negligible and lower than that of succinate. The seminal root of Trapa compares better to the rice coleoptile rather than to the rice root, both functionally and as to the metabolic response to anoxia. The anaerobic germination of Nuphar luteum L. and Scirpus mucronatus L. was also characterized by a limited developmental program.     

Potential of some Metarhizium anisopliae isolates for control of Culex quinquefasciatus (Dipt., Culicidae)

Abstract: The potential of some isolates of Metarhizium anisopliae and Beauveria bassiana for use in the integrated management of Culex quinquefasciatus was evaluated. Metarhizium anisopliae isolate 1037 was selected in initial bioassays with a 50% lethal concentration (LC₅₀) of 1.97 × 10⁴ conidia/ml. This fungus caused higher mosquito larva mortality when applied as a conidial suspension to the surface of the water than as dry conidia, with a time to 50% lethal (LT₅₀) of 1 day compared with 3.6 days for the dry conidial application. However, results with UV- and heat-inactivated conidia did not confirm a possible role of fungal toxins in causing mortality when ingested by C. quinquefasciatus larvae. Metarhizium anisopliae did not remain active for as long as the bacterium Bacillus sphaericus isolate 2362. At 24 h after application, the fungus-induced mortality on mosquito larvae was significantly lower than the mortality caused by the bacterium. By the second day, almost no activity by the fungus was observed. Results suggest that M. anisopliae isolate 1037 has potential for use in mosquito control programmes.     

Egg-to-fry survival of the sea trout in some streams of Gotland

The quality of the surface water of Gotland (Sweden) streams was good, and did not limit sea trout egg-to-fry (ETF) survival. The oxygen concentration of the interstitial water was positively correlated to the permeability of the stream bed, and to the geometric mean diameter of the substratum. When the oxygen at 15 cm inside the stream bed was undiminished from surface values, the permeability of the stream bed was at least 6000 cm h^–1 and the geometric mean diameter of the substratum at least 15.0 mm. When the interstitial oxygen concentration increased, the interstitial ammonium concentration decreased, the NO₂ concentration remained stable and the NO₃ concentration increased. The ETF survival up to hatching was highly dependent upon the oxygen concentration of the interstitial water. For survival from hatching to emergence, the geometric mean diameter of the substratum was the most important factor. ETF survival >50% was observed where the interstitial oxygen concentration averaged at least 10mg I-¹, the substratum permeability at least 2000cm h-¹ and the substratum geometric mean diameter at least 15 mm. Other factors, such as overdigging and drying out of the spawning grounds could increase the ETF mortality.     

The effect of moisture potential on growth and survival of root nodule bacteria in peat culture and on seed

Peat from three sources was dried, milled and packed separately in polyethylene bags and sterilized by irradiation. The carrier was impregnated with broth cultures of either Rhizobium leguminosarum bv. trifolii strain WU95, Bradyrhizobium japonicum strain CB1809 or B. lupini strain WU425 and sterile water to provide five moisture potentials in the range > - 1 × 10⁴ - 1 × 10⁶ Pa. The packets were stored at 26°C under conditions which restricted moisture loss. Numbers of root nodule bacteria were counted at intervals up to 12 weeks. No single moisture potential was optimum for all strains in all carriers because of a significant ( P < 0.05) interaction between moisture potential × strain × carrier × time. Where direct comparisons could be made, all strains survived best at - 1 × 10⁴ and/or −3.2 × 10⁴ Pa. Seeds of Trifolium subterraneum and polypropylene beads (used to avoid seed coat toxicity), were inoculated with WU95 prepared in two sources of peat and at each of the above moisture potentials and stored at 15°C. Seed coat toxicity significantly effected the log death rate ( k ) of WU95 on subterraneum clover seed for the period 0–0.25 d ( k 1.796) compared with k - 0.399 for polypropylene beads. In the first 24 h moisture did not affect survival but by 28 d rhizobia grown in Badenoch peat survived best at −3.2 × 10⁴ Pa. In Millicent peat, survival was equally as good at −3.2 × 10⁴ and −1 × 10⁴ Pa.     

Physiological aspects of Taxus brevifolia seeds in relation to seed storage characteristics

Water relations, desiccation tolerance and longevity of Taxus brevifolia (Nutt.) seeds were studied to determine the optimal stage of development and storage conditions for seeds of this species. Seeds equilibrated to a range of relative humidities (RHs) had unusually low water contents which can be accounted for by the high lipid content of gametophyte tissues (71% of the dry mass). Water relations of embryonic tissue were more typical of those reported for other seed species. The water content below which freezing transitions were not observable in the embryo was ca 0.24 g H₂O (g dry weight)⁻¹ (g g⁻¹) for all maturity classes studied. Embryos did not achieve significant levels of desiccation tolerance (survival to water contents less than 0.5 g g⁻¹) until the latter stages of development when dry matter was maximal. Mature embryos could be dried to 0.025 g g⁻¹ (seed water content of 0.010 g g⁻¹) with no loss of viability. Thus, at the latter stages of development, embryo water content could be optimized to avoid both desiccation and freezing damage. Survival of mature seeds declined over a 2-year period when seeds were stored at temperatures between 5 and 35°C and RHs between 14 and 75%, corresponding to seed water contents between 0.015 and 0.07 g g⁻¹. The deterioration rate was slowest for seeds stored at the lowest RH and temperature. Our data indicate that seeds of Taxus brevifolia show orthodox rather than recalcitrant storage characteristics, but that the optimum water content for storage was extremely low. The results suggest that even if stored at optimal water contents and low temperatures, T. brevifolia seeds will be relatively short lived. The high quantity of lipids or reducing sugars may be contributing factors in the poor storage characteristics.