Temperature influence on cohort parameters and demographic characteristics of the two cowpea coreids Clavigralla tomentosicollis and C. shadabi

Age-specific life tables of two important pests of cowpea, Vigna unguiculata (L.) Walp., the pod sucking bugs Clavigralla tomentosicollis Stål and C. shadabi Dolling (Heteroptera: Coreidae), were obtained from observations carried out at different temperatures. A biophysical model was found satisfactory to describe the temperature-response of developmental and mortality rates of egg and nymphal stages, with a peak developmental rate around 34°C in both species. The variability in development times was small and the experimental data did not permit any conclusion with regard to the Erlang probability density function. Survival of eggs and nymphs remained high between 20° and 30°C for both species. At temperatures above 34°C, C. tomentosicollis survivorship and fecundity was higher than that of C. shadabi, which in turn laid more eggs at temperatures between 20° and 30°C. Maximum fecundity is estimated to be at 29°C for C. tomentosicollis (99 eggs/female) and 26°C for C. shadabi (261 eggs/female). At 30°C, the intrinsic rate of increase reached a maximum in both species, 0.152 per day for C. tomentosicollis and 0.145 per day for C. shadabi, and remained high for C. tomentosicollis until 36°C. C. tomentosicollis performed significantly better on pigeonpea, Cajanus cajan Millsp., than on cowpea at higher temperatures.     

Growth,production, and demography of Moina micrura in brackish tropical fishponds (Layo,Ivory Coast)

Sampling and experiments were performed in brackish fishponds, located near the Ebrie Lagoon, Ivory Coast. Moina developed here at salinities up to about 4 g l^-1. Mean embryonic and juvenile development times in experimental conditions were 0.82 and 0.80 day, respectively, with 2 juvenile stages at 30 °C (salinity of 3 g l^-1; 29 µg chlorophyll-a l^-1) and 1.22 and 1.37, with 2 stages for most individuals and 3 or 4 stages for some of them at 26 °C (2 g l^-1 and 36 µg l^-1). The corresponding Q₁₀ for embryonic development was relatively high (2.7). Growth rates in weight at 30 ° C were 2.11 and 1.37 µg µg^-1 d^-1, respectively, for the embryonic and juvenile stages, 0.21 for mean somatic growth of the five first female adult stages, and 1.00 for primipara, summed for somatic growth, production of eggs, and embryonic growth. Consequently, differences in growth rates between young and adults were small. M. micrura also was a high fecundity species according to its size, fecundity in nature varying from 2.2 to 7.7 eggs per adult female. Rates of population increase evaluated for some sequences of parthenogenetic growing periods, reached up to 0.9. Most of the daily P/B evaluated by the cumulative growth method reached values above 1.0 (28 to 31 °C), minima being about 0.7 for lower temperatures (approximatively 26 °C). Populations were also characterized by low juvenile to adult ratios (down to 0.9) and high daily birth rates (up to 1.2). Overall, M. micrura is a highly productive, opportunistic species, well adapted to the low salinities that occur during part of the year in the ponds.Biological and population characteristics of this species, and literature data on regulation mechanisms, possible use for aquaculture, and on size in tropical species are discussed.     

Temperature preferences and tolerances of three fish species inhabiting hyperthermal ponds on mangrove islands

The fish species Cyprinidon artifrons, Floridichthys carpio, and Gambusia yucatana inhabit shallow mangrove ponds off the coast of Belize. Portions of these ponds experience a diurnal temperature change from 26 °C at night to 40 °C and above during midday. Repeated field observations indicate Cyprinidon prefer the warmer (and much larger) portions of the ponds whereas the other two species stay in the cooler areas.The hypothesis that temperature is serving as a cue for partitioning within the ponds was supported by laboratory thermal gradient tests in which Cyprinidon preferred temperatures clearly higher than the other two species.The critical thermal maximum (CTM) was determined for the three species using members that had been acclimated to either a daily cycling temperature similar to that for the ponds, or to the mean of the 24-hour cycle (30 °C). Cyprinidon acclimated to the cycling temperature had a CTM of 45.5 °C, which apparently sets a new record for fish CTM. Acclimation to a constant 30 °C lowered the CTM to 43.7 °C. Floridichthys and Gambusia acclimated to the cycled temperature had CTMs of 43.9 and 43.3 °C respectively, and 42.5 and 42.6 °C for those acclimated to 30 °C.All three species appear to have the ability to tolerate the high temperatures throughout the ponds but only Cyprinidon utilize the whole pond during the day. This may help to explain the large populations of Cyprinodon found in these mangrove ponds compared to the other species.     

Temperature dependent development and survival of two sympatric species, Galerucella calmariensis and G. pusilla, on purple loosestrife

Two sympatric Europeanbeetles, Galerucella calmariensis (L.)and G. pusilla (Duft.) (Coleoptera:Chrysomelidae), have been released in NorthAmerica for biological control of purpleloosestrife, Lythrum salicaria L.(Lythraceae). Because establishment isaffected by environmental conditions, studieswere conducted at temperatures ranging from12.5 to 30 °C to determine differencesin rate of development and survival between thetwo species. No egg hatch occurred at12.5 °C for both species. Eggdevelopment was faster for G.calmariensis than for G. pusilla attemperatures 15 °C. Theminimum threshold temperature for eggdevelopment was lower for G. calmariensisthan G. pusilla. At 12.5 °C, G. calmariensis larvae developed 1.6 daysfaster than G. pusilla, but at 15, 20,25, and 27.5 °C G. pusilla developed2.9, 1.2, 1.1, and 0.6 days faster,respectively, than G. calmariensis. Nodifferences in developmental rate of pupa andtotal development time from egg to adulteclosion were observed for the two species. However, survival of G. calmariensisgenerally was higher than that of G.pusilla at lower temperatures. No differencewas observed in the preoviposition periodbetween the two species except at27.5 °C. The preoviposition period forboth species at 12.5 and 15 °C exceeded50 days and was much higher than for20 °C and above. The long preovipositionperiod suggests that temperatures below15 °C induce reproductive diapause. At15 °C, G. pusilla females livedlonger and also had a longer oviposition periodthan G. calmariensis. However, fasteregg and larval development, and higher survivalat 12.5 °C may give G. calmariensisa competitive advantage over G. pusillain cooler climates.     

Effect of constant temperatures on germination, radial growth and virulence of Metarhizium anisopliae to three species of African tephritid fruit flies

The effect of temperatureon conidial germination, mycelial growth, andsusceptibility of adults of three tephritidfruit flies, Ceratitis capitata(Wiedemann), C. fasciventris (Bezzi) andC. cosyra (Walker) to six isolatesof Metarhizium anisopliae were studied inthe laboratory. There were significantdifferences among the isolates in the effect oftemperature on both germination and growth.Over 80% of conidia germinated at 20, 25 and30°C, while between 26 and 67% conidiagerminated at 35°C and less than 10% at15°C within 24 hours. Radial growth was slowat 15°C and 35°C with all of theisolates. The optimum temperature forgermination and mycelial growth was 25°C. Mortality caused by the six fungal isolatesagainst the three fruit fly species varied withtemperature, isolate, and fruit fly species.Fungal isolates were more effective at 25, 30and 35°C than at 20°C. The LT₉₀values decreased with increasing temperature upto the optimum temperature of 30°C. Therewere significant differences in susceptibilitybetween fly species to fungal infection at allthe temperatures tested.     

Diapause induction in the codling moth, Cydia pomonella: effect of prediapause temperatures

The effect of four prediapause temperatures (18, 22, 26 and 30°C) on the photoperiodic response of the codling moth, Cydia pomonella (L.), was studied under controlled conditions. The highest rates of diapause were recorded, for all day-lengths, at temperatures of 22 and 26°C while relatively lower rates of diapause were elicited at 18 and 30°C. The same trend was demonstrated by projecting the values of the critical photoperiod which induces 50% diapause (=CPhP₅₀) over the prediapause temperature. The change in diapause incidence as a function of photoperiod, at all prediapause temperatures, exhibited a response characteristic of long-day insects, i.e. high rates of diapause at short days (12–13.5 h) and a decrease in diapause incidence at long days (14–15 h). The results for temperatures 22, 26 and 30°C support the view that lower prediapause temperatures enhance diapause induction, at a give photoperiod, while higher temperatures tend to avert or diminish the process. On the other hand, the low rates of diapause obtained at 18°C contradict this view. Nevertheless, high correlation was found between the laboratory evidence and field data, indicating the adaptability of the Israeli codling moth to subtropical climate.     

Effects of ambient Lake Mohave temperatures on development,oxygen consumption,and hatching success of the razorback sucker

Synopsis Spawning of razorback suckers,Xyrauchen texanus, in Lake Mohave occurred from 10–22°C and larvae were collected at water temperatures from 10–15°C in 1982 and 1983. In the laboratory, hatching success was similar from 12–20°C, but reduced hatching success was found at 10°C while none hatched a 8°C. Development rate and oxygen consumption were positively related to incubation temperature. Direct effects of ambient Lake Mohave water temperatures on hatching success of razorback sucker embryos are considered minimal. Historical spawning temperatures for the species are hypothesized based upon successful incubation temperatures and comparison to the white sucker,Catostomus commersoni.     

Development Models for the Filth Fly ParasitoidsSpalangia gemina, S. cameroni,andMuscidifurax raptor(Hymenoptera: Pteromalidae) under Constant and Variable Temperatures

Development rates were determined for three pteromalid parasitoids of houseflies under constant and varying temperatures from 15 to 35°C.Muscidifurax raptorGirault and Sanders was the fastest developing species, with females completing development in 13.8 days at 32.5°C and 66.5 days at 15°C.Spalangia geminaBoucek females completed development in 20.8 days at 30.0°C and 161 days at 15.0°C, whereasS. cameroniPerkins females completed development in 20.6 days at 30.0°C and 155.5 days at 15.0°C. Male development times were 90.3% of those for femaleS. geminaand 92.7 and 88.6% of those for femaleS. cameroniandM. raptor,respectively. Parasitoid survival was very low at 35°C for all species and noSpalangiasurvived constant exposure to 15.0°C. Exposure to these lethal temperatures for shorter periods indicated that the parasitoids can tolerate them well under conditions more typical of the field. Development rates were modeled using biophysical and degree-day models and the models were tested for their ability to predict development under fluctuating conditions (24–36°C). Neither model was superior for all three species because of interspecific differences in the parasitoids' responses to high temperatures. Agreement between predicted and observed development times for all three species was achieved by small empirical adjustments of a key parameter in the biophysical model.     

Effect of temperature on the duration of larval and pupal stages of two species of sciomyzid flies, predators of the snail Lymnaea truncatula

The duration of larval and pupal stages of two species of predatory flies was investigated at five constant temperatures. Ilione albiseta (Scopoli): Mean duration of first and second instars was shortest at 23°C and there was 100% survival of first instar larvae at all temperatures. Mean third instar larval duration decreased from 104 days at 17°C to 27.5 days at 26°C. Total percentage larval survival was greatest at 17°C and least at 26°C. Mean pupal duration decreased as temperature increased and this occurred also under outdoor conditions. Pherbellia cinerella (Fallén): As temperature increased mean larval duration decreased but the percentage of larvae pupating also decreased (100% at 14°C, 33.3% at 26°C). There was a trend for shorter mean pupal durations at higher temperatures.

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Résumé L'action de la température a été examinée à 14, 17, 20, 23 et 26°C. Les 2 espèces sont prédatrices de L. truncatula, vecteur de la douve du foie en Irlande, où elle provoque à l'àgriculture une perte évaluée à 10 millions de livres par an. Les données recuellies en conditions contrôlées du laboratoire doivent permettre de définir les conditions optimales pour l'élevage continu de ces espèces. Ceci est indispensable pour évaluer, dans la nature leurs potentialités pour la lutte biologique. Ilione albiseta: C'est à 23°C que le développement des larves de premier et second stades sont les plus brefs; la survie du premier stade est totale à toutes les températures constantes examinées. La durée moyenne du 3ème stade décroît de 104 jours à 17°C jusqu'à 27,5 jours à 26°C. Le taux de survie total est plus élevé à 17°C qu'à 26°C. La durée moyenne de la nymphose diminue quand la température croît, et ceci se produit aussi à la température ambiante extérieure. On réduit de moitié la durée du développement de l'éclosion de l'oeuf à l'apparition de l'adulte, entre la nature et le laboratoire, en utilisant respectivement: 23°, 17° et 26°C pour les premier et second stades, le troisième stade, la nymphé. Cela devrait aider à multiplier la souche pour la lutte biologique. Pherbellia cinerella: Avec élévation de la température la durée du développement larvaire diminue, mais aussi le nombre de larves parvenant à la pupaison (100% à 14° et 33,3% à 26°C). La nymphose tendait à être plus brève aux températures les plus élevées.

     

Flowering of Watsonia laccata as influenced by corm storage and forcing temperatures

The genus Watsonia, belonging to the family Iridaceae, is comprised of about 50 species including W. laccata (Jacquin) Ker Gawler that flowers from September to November following low temperature and winter rainfall. Therefore, we hypothesized that flowering would be favored by forcing at low greenhouse temperatures. Using clonal W. laccata corms, four experiments were designed to investigate the effect of temperatures during corm storage, forcing, and their interaction on growth and flowering. Corm formation is favored by growing plants at 18°–20°/15°–17 °C and 21°–23°/18°–20 °C, day/night temperatures. Flowering was earliest with corms produced at 24°–26°/18°–20 °C and forced at 18°–20/15°–17 °C, and was significantly delayed when forced at 27°–29°/24°–26 °C. Flowering was, however, favored by 2 or 4 weeks of high temperatures (27°–29°/24°–26 °C) prior to forcing at low temperatures (18°–20°/15°–17 °C). The number of florets was not significantly affected by corm storage, forcing temperatures, or their interaction, although forcing at high temperatures tends to reduce the floret number. Burn symptom at the tips of leaves was frequently observed, and further studies are required to understand the cause of the tip burn and how to correct the symptom.     

The ecology of Synchaeta kitina Rousselet in Loch Leven,Scotland

Synchaeta kitina Rousselet reached population densities of up to 5000 ind.l^–1 in Loch Leven, between January 1977 and December 1982. The species was found over the entire range of temperatures recorded (0.4–21.4 °C), but was most abundant at temperatures above 7 °C. Embryo development times, determined under laboratory conditions, ranged from 122 h at 2 °C to 12.5 h at 20 °C. There was a marked inverse relationship between populations of S. kitina and Daphnia hyalina var. lacustris in the loch. It seems unlikely that this was due to interference competition from Daphnia. S. kitina can be cultured on Rhodomonas minuta var. lacustris and there is some evidence that this rotifer also feeds on small flagellates in its natural environment.     

Effects of species of VA-mycorrhizal fungi on growth and mineral uptake of sorghum at different temperatures

Sorghum [Sorghum bicolor (L.) Moench] plants were grown in growth chambers at 20, 25 and 30°C in a low P Typic Argiudoll (3.65 µg P g^–1 soil, pH 8.3) inoculated with Glomus fasciculatum, Glomus intraradices, and Glomus macrocarpum to determine effects of vesicular-arbuscular mycorrhizal fungi (VAMF) species on plant growth and mineral nutrient uptake. Sorghum root colonization by VAMF and plant responses to Glomus species were temperature dependent. G. macrocarpum colonized sorghum roots best and enhanced plant growth and mineral uptake considerably more than the other VAMF species, especially at 30°C. G. fasciculatum enhanced shoot growth at 20 and 25°C, and mineral uptake only at 20°C. G. intraradices depressed shoot growth and mineral uptake at 30°C. G. macrocarpum enhanced shoot P, K, and Zn at all temperatures, and Fe at 25 and 30°C above that which could be accounted for by increased biomass. Sorghum plant growth responses to colonization by VAMF species may need to be evaluated at different temperatures to optimize beneficial effects.     

Ecological aspects of thermoregulation at high altitudes: the case of andean Liolaemus lizards in northern Chile

Summary We document activity field temperatures, daily activity patterns, and extent of thermoregulation in four species of Liolaemus lizards inhabiting at high altitude (above 3500 m) in the Andes of northern Chile. These four species have similar activity field temperature (Tb near 29°C) despite their being distributed at different altitudinal belts. However, conspicuous differences exist between higher-altitude (L. alticolor and L. jamesi) and lower-altitude (L. islugensis and L. ornatus) lizards regarding extent of thermoregulation and activity period. Some differences in morphology, behavior, and patterns of microhabitat occupancy are also apparent among these four species and are seemingly related to the thermal environment to which they are subjected. In comparison to eight low-altitude Liolaemus species in central Chile (Tb near 35°C) the four high-altitude species in northern Chile have lower activity field temperature. The latter is apparently due to the constraints imposed by the harsh Andean thermal environment, a hypothesis supported by the fact that high-altitude Liolaemus lizards under laboratory conditions demonstrate body temperatures that exceed by 5°C or more, those recorded in the field.     

Influence of root temperature on growth of Pinus sylvestris,Fagus sylvatica,Tilia cordata and Quercus robur

One-year-old tree seedlings were incubated in a greenhouse from April to July, under natural daylight conditions, with their root systems at constant temperatures of 5, 10, 15, 20, 25, 30 and 35 °C and with the above ground parts kept at a constant air temperature of 18–20 °C. The course of height growth, total mass increment, root, shoot and leaf weight as well as leaf areas were measured. The results indicate that clear differences exist in the optimal root zone temperatures for various growth parameters in different tree species. Pinus sylvestris had a maximal height increment at about 5–10 °C and maximal total mass increment at 15 °C root temperature. In contrast, the optimum for Quercus robur was at 25 °C. Tilia cordata and Fagus sylvatica had their optima for most growth parameters at 20 °C. The root temperature apparently indirectly influenced photosynthesis (dry weight accumulation) and respiration loss. From the observed symptoms and indications in the literature it seems probable that a change in hormone levels is involved as the main factor in the described effects. Variation of root temperature had only an insignificant effect on bud burst and the time at which the shoots sprouted. Apparently species of northern origin seem to have lower root temperature optima than those of more southern origin. This is to be verified by investigation of other tree species.     

Survival of sub-zero temperatures by two South Georgian beetles (Coleoptera,Perimylopidae)

Summary The ability of adults and larvae of two species of perimylopid beetles (Hydromedion sparsutum, Perimylops antarcticus) to survive sub-zero temperatures was studied at Husvik, South Georgia in summer during October–December 1990. Experiments determined their survival at constant sub-zero temperatures, their lower lethal temperatures and individual supercooling points. The effects of cooling rates (0.015°, 0.5° and 2.0°C min^–1) and starvation on survival were also assessed. Mean supercooling points of field-collected individuals of both species were in the range -3.0° to -5.4°C with Perimylops having a deeper capacity (ca. 1.5°C) for supercooling relative to Hydromedion. The former species also survived freezing temperatures significantly better than the latter and its mean lower lethal temperature was 2.5°C lower. At a constant temperature of -8.5°C, the median survival times for Perimylops adults and larvae were 19 and 26 h respectively, whilst both stages of Hydromedion died within 3 h. The three cooling rates resulted in significantly different median survival temperatures for adult Hydromedion with 0.5°C min^–1 producing maximum survival. Prior starvation did not have a significant influence on the survival of either species at sub-zero temperatures although both adults survived less well. The results support field observations on the habitats and distribution of these insects, and suggest differing degrees of freezing tolerance.     

Egg production in response to combined alternative foods by the predator Coccinella transversalis

The peformance of the parasitoid Anagyrus kamali Moursi [Hymenoptera: Encyrtidae], as a function of host density, temperature, and photoperiod was investigated with the objective to optimize a mass-rearing system in the context of a biological control program. The number of hosts parasitized at densities varying from 2–100 hibiscus mealybug (HMB), Maconellicoccus hirsutus Green [Homoptera: Pseudococcidae], corresponded to a type II-III functional response in fixed-time conditions and a type III in variable-time conditions. Twenty-six percent of the oviposited eggs led to progeny emergence with a sex ratio of 0.49±0.102 (M/F), regardless of host density. Fecundity and oviposition period under six abiotic combinations (i.e., two temperatures (26±2 °C and 32±2 °C) and three photoperiods (L0:D24, L12:D12, L24:D0)) were measured. Lifetime fecundity and reproductive life were significantly affected by temperature and photoperiod conditions. Optimum female parasitoid lifetime fecundity was attained at 26±2 °C, L0:D24 with an average of 116.1±17.43 eggs. At 32±2 °C, L24:D0 and L12:D12, an average of 79.4±34.57 and 85.8±35.81 eggs were laid, respectively. Reproductive longevity was maximal at 26±2 °C, L0:D24 with 12±4.85 days of oviposition. Because the parasite A. kamali can be reared optimally without light, this may save tremendous energy costs.     

Embryonic development of orchard leafrollers and the forecasting of egg hatch

The development time of eggs of three of the most noxious leafrollers found in Northeuropean orchards, Spilonota ocellana (Denis & Schiffermüller), Archips podana (Scopoli), and Pandemis heparana (Denis & Schiffermüller) (Lepidoptera: Tortricidae) was recorded in the laboratory at five constant temperatures between 14 and 25°C. In this range, developmental rates of the three species did not differ significantly. While the flight periods of these species overlap largely, a single algorithm could be used to devise optimal spraying time(s) for the three species.     

Temperature preferences and oxygen consumption of three species of sculpin (Cottus) from the Pit River drainage,California

Synopsis I examined the temperature preferences and routine metabolic rates of Pit sculpin, Cottius pitensis, marbled sculpin, C. klamathensis macrops, and rough sculpin, C. asperrimus, of the Pit River drainage of California to determine if the distributional patterns of these species can be explained on the basis of physiological or behavioral responses to temperature. The routine metabolic rates of these species did not increase significantly between 10 and 15°C, indicating an area of thermal compensation. Metabolic rates then rapidly increased between 15 and 20°C (Q₁₀ values>4.0) followed by little increase between 20 and 25°C (Q₁₀ values >2.0), indicating another area of thermal compensation. The final temperature preferenda of Pit, marbled and rough sculpin were 11.2, 12.1 and 13.5°C, respectively. Marbled and rough sculpin appear to be more stenothermal than Pit sculpin. At acclimation temperatures of 10, 15 and 20°C the acute preferred temperatures of marbled and rough sculpin ranged from 11.1 to 14.7° C and 13.3 to 14.4°C, respectively. Values for Pit sculpin ranged from 9.9 to 16.4°C at acclimation temperatures of 10, 15 and 20°C. The distributions of marbled and rough sculpin are consistent with their behavioral and metabolic responses to temperature. The widespread distribution of Pit sculpin is consistent with its greater tolerance of high temperatures and eurythermal behavior, but the absence of Pit sculpin from habitats dominated by marbled and rough sculpin is not consistent with a temperature related explanation.     

Progeny production and adult longevity of the mealybug parasitoidsAnagyrus pseudococci,Leptomastix dactylopii,andLeptomastidea abnormis [Hym.: Encyrtidae] in relation to temperature

Progeny production increased and adult longevity decreased with rising temperature within the range 18°C to 30°C for the 3 mealybug parasitoidsAnagyrus pseudococci (Girault),Leptomastix dactylopii Howard andLeptomastidea abnormis (Girault). The Weibull distribution gave a good fit to survival curves for the 3 parasitoids and statistical comparison of Weibullb andc parameters at different temperatures allowed changes in the scale and shape of the curves to be detected. In general, ♀♀ lived longer than ♂♂ for all 3 species, except at high temperature. FemaleL. abnormis attained their maximum progeny production at 24°C and maintained this level up to 34°C. They lived longer than the other 2 parasitoid species at 30°C and showed a type I survival curve throuhout the range of temperatures examined.A. pseudococci andL. dactylopii both required high temperatures (30°C) to attain their maximal progeny production, but werepseudococci tended towards type II, with a larger proportion of the population dying within the first few days.L. dactylopii lived longest at 26°C, with ♀♀ showing a type I survival curve at all temperatures and ♂ survival curves changing from type I to type II at 30°C. The implications of these findings for the population dynamics of the different parasitoids are briefly discussed.      

Photosynthesis and growth rates of Laurencia brongniartii J. Agardh (Rhodophyta, Ceramiales) in preparation for cultivation

Laurencia brongniartii is usually found at depths below 4 m, but can be found in shallow subtidal areas in crevices and on the walls of a coral reef in Amami Oshima Island, Kagoshima Prefecture, Japan, where irradiances were significantly lower than those at similar depths in open water. In preparation for the possible cultivation of this species for its antibiotic compounds, the effects of temperature and irradiance on photosynthesis and growth were measured. Photosynthesis and growth rates of L. brongniartii explants were highest at 26 and 28 °C, which closely corresponded to temperatures found during August to late December when it was most abundant. The estimated maximum photosynthesis rate (P _max) was 4.41 mol photon m^–2 s^–1 at 26 °C and 4.07 mol photon m^–2 s^–1 at 28 °C. Saturating irradiance occurred at 95 mol photon m^–2 s^–1 at 26 °C and 65 mol photon m^–2 s^–1 at 28 °C. In contrast, growth experiments at 41.7 mol photon m^–2 s^–1 caused bleaching of explants and the maximum growth rate observed during the study was 3.02 ± 0.75% day^–1 at 28 °C and 25 mol photon m^–2 s^–1. The difference in the saturating irradiance for photosynthesis and the irradiance that caused bleaching in growth experiments suggests that long-term exposure to high irradiance was detrimental and should be addressed before the initiation of large scale cultivation.