Functional response of the predator <Emphasis Type="Italic">Scolothrips takahashii</Emphasis> to hawthorn spider mite, <Emphasis Type="Italic">Tetranychus viennensis</Emphasis>: effect of age and temperature

A leaf disc bioassay was employed to examine the effects of temperature and predator age on functional response of an acarophagous thrips, Scolothrips takahashii Priesner, to hawthorn spider mite, Tetranychus viennensis Zacher, in the laboratory. The results indicated that the predatory thrips exhibited type-II functional responses against the mites under various temperatures, and that females are more voracious than males. Analysis showed that temperature had significant effects on the predatory capacity of adult thrips over the range of 20–35 °C. Attack rate in females linearly increased with temperature while in males it was independent of temperature. Handling times in both males and females decreased linearly with increasing temperature. Extended response models describing the functional response with temperature incorporated as a parameter were developed, yielding an estimated maximum numbers of prey attacked at four temperatures were 38.38, 55.06, 71.74 and 88.42 eggs per day for females, and 15.11, 26.11, 37.11 and 48.01 eggs per day for males, respectively. The age of predator affected both the type of the functional response shown and the magnitude of predation by S.␣takahashii on the spider mite. Females of various ages exhibited Type-II functional responses with similar attack rates, but handling time prolonged linearly as age increased: the handling times in 15- and 18-d-old females were significantly longer than in 6-d-old thrips. However, Type-I functional responses were determined for males aged 12 d or more; the maximum number of prey eaten in 24 h decreased as age increased. The implications of the results for the management of hawthorn spider mite are discussed.     

Feeding by marine fish larvae: developmental and functional responses

Synopsis The relationship between prey consumption rate and prey concentration (functional response), and its change with growth (developmental response) were examined in the laboratory for three species of marine fish larvae: bay anchovy Anchoa mitchilli (Engraulidae), sea bream Archosargus rhomboidalis (Sparidae) and lined sole Achirus lineatus (Soleidae). The major objective was to determine relative predatory abilities of the larvae by fitting feeding rate data to developmental and functional response models. Feeding success, prey capture success, attack rates, handling times and search rates were estimated. Prey consumption rates and attack rates of bay anchovy usually were highest, but at the lowest prey level (50 per liter) first-feeding sea bream larvae had the highest consumption rate. Sea bream could consume prey at near-maximum rates at prey levels lower than those required by the other species. As larvae grew, time searching per attack decreased rapidly for all species, especially at low prey levels. Handling time also decreased, but most rapidly for bay anchovy. Search rates were highest for bay anchovy and lowest for lined sole. Bay anchovy had the best apparent predation ability, but when previous results on larval growth rates, survival rates and growth efficiencies were considered, sea bream larvae were the most efficient predators and the least likely of the three species to be limited by low prey levels.     

Diversity of juvenile fish assemblages in the pelagic waters of Lebanon (eastern Mediterranean)

Oxygen consumption rates of nauplii of the brine shrimp Artemia franciscana Kellogg 1906 were determined over a range of salinities from 10 to 110 ppm, in temperatures from 0 to 30°C, using a multi-factorial design. The oxygen micro-sensors employed have a fast response time and are capable of accurately measuring oxygen concentrations at temperatures well below 0°C. Oxygen uptake rate ranged from 0.03 to 0.66 μmol O₂ mg⁻¹ h⁻¹ and was sensitive to changes in both salinity and temperature. Temperature was the dominant factor affecting oxygen consumption rates, which showed a significant increase with increasing temperature. A slight decrease was measured in oxygen consumption with increasing salinity related to differential solubility of oxygen in waters of different salinities. Thermal sensitivity of oxygen consumption determined from calculations of Q ₁₀, indicated physiological adaptation of Artemia nauplii to the ranges of temperatures tested. Handling editor: A. van Kerchove     

Functional response of a parasitoid Ganaspidium utilis （Hymenoptera： Eucoilidae） on the leafminer Liriomyza trifolii （Diptera： Agromyzidae）

Functional response of a solitary, larval-pupal endoparasitoid of Liriomyza leafminers, Ganaspidium utilis Beardsley, was estimated on Liriomyza trifolii Burgess at three temperatures （17℃, 25℃, 29℃ ） and host densities. A type Ⅱ random parasitoid equation （RPE） was used to estimate instantaneous search rate and handling time. The instantaneous search rate increased as temperature increased. All of the RPE regressions obtained for functional response of G. utilis at different temperatures were significant （P〈0.01）. The slope of RPE regression lines was lower across the temperatures. At 29±2℃, the maximum number of larvae parasitized was 7.8 per day. It decreased to 7.2 larvae parasitized at 25±2℃. At 17±2℃, no significant increment of parasitization was observed due to the host density increments. The estimated handling time was lowest at 17±2℃ and highest at 25 ± 2℃, respectively. The ability of G. utilis to find and parasitize L. trifolii over a wide range of temperatures makes them a good candidate for biological control of Liriomyza leafminers.     

A laboratory study of the feeding of Mesostoma lingua (Schmidt) (Turbellaria: Neorhabdocoela) on Daphnia magna Straus at four different temperatures

Mesostoma lingua eats 0.8 Daphnia magna at 15 °C, and 2.04 at 30 °C. Below 0.5 Daphnia per day (D d^–1) hunger occurs, at any temperature, and mortality increases sharply. The functional response curve appears to be linear, but saturation was not fully reached at 5 D d^–1, the highest food level applied in the present study. All food regimes (above hunger level) and temperature regimes differed significantly from each other; factor interactions were of increasing importance at higher temperatures.Longevity, above hunger level, decreased with temperature. Peak longevity at low temperature may be weakly associated with relatively low food levels.     

Temperature dependent functional response ofEncarsia formosa parasitizing the Poinsettia-strain of the cotton whitefly,bemisia tabaci, on Poinsettia

The control efficiency and performance ofEncarsia formosa Gahan (Hymenoptera: Aphelinidae) as influenced by the density of its host, the Poinsettia-strain ofBemisia tabaci Gennadius (Homoptera: Aleyrodidae), were investigated by laboratory experiments on Poinsettia (Euphorbia pulcherrrima Willd.).E. formosa showed a Type II functional response to fourth instar larvae ofB. tabaci, the response plateau increasing with temperature. A response model for randomly searching parasitoids incorporating temperature-dependent handling time and temperature-independent search rate was in accordance with the results, and gave an estimated search rate of 0.033 leaf·hour⁻¹ and handling times of 1.54, 2.86 and 20.1 h at 28°C, 22°C and 16°C, respectively. From the latter, the maximum number of hosts that can be parasitized at the three temperatures are 10.4, 5.6 and 0.8 larvae per day (provided the light period is 16 h). The number of hosts with ovipositor punctures was higher than the number of parasitized hosts, especially at 22°C and 28°C, implying thatE. formosa refrains from laying eggs in some of the hosts examined with the ovipositor. About 31% of the punctured larvae did not contain any eggs. Superparasitism occured during the experiment presumably originating from young, inexperienced parasitoids. Individual larvae were occasionally punctured several times, also by non-superparasitizingE. formosa. The resulting distribution of ovipositior holes was random, indicating thatE. formosa on the basis of antennal testing is unable to determine if a larva has previously been examined with the ovipositor. Almost fifty percent of the punctures were not followed by egg-depositions. Besides parasitizationE. formosa used hosts as food source. The number of hostfed larvae was independent of density, but varied with temperature being highest at 28°C (0.12 hostfed larvae per parasitoid per day).     

Spatial response properties of homing pigeon hippocampal neurons: correlations with goal locations,movement between goals,and environmental context in a radial-arm arena

The amniote hippocampal formation plays an evolutionarily-conserved role in the neural representation of environmental space. However, species differences in spatial ecology nurture the expectation of species differences in how hippocampal neurons represent space. To determine the spatial response properties of homing pigeon (Columba livia) HFneurons, we recorded from isolated units in birds freely navigating a radial arena in search of food present at four goal locations. Fifty of 76 neurons displayed firing rate variations that could be placed into three response categories. Location cells (n=25) displayed higher firing rates at restricted locations in the arena space, often in proximity to goal locations. Path cells (n=13) displayed higher firing rates as a pigeon moved between a subset of goal locations. Arena-off cells (n=12) were more active when a pigeon was in a baseline holding space compared to inside the arena. Overall, reliability and coherence scores of the recorded neurons were lower compared to rat place cells. The differences in the spatial response profiles of pigeon hippocampal formation neurons, when compared to rats, provide a departure point for better understanding the relationship between spatial behavior and how hippocampal formation neurons participate in the representation of space.     

Day-night rhythms in opiate modulation of body temperature in male Japanese quail

Summary Male Japanese quail,Coturnix coturnix japonica, displayed day-night rhythms in their body temperature, with significantly higher temperatures during the day than at night. There were individual variations in both the temperatures attained and amplitude of the day-night rhythm of body temperature in the group-housed birds. Accompanying these diurnal patterns in body temperature there were day-night rhythms in the effects of intraperitoneal administrations of the opiate agonist, morphine (1.0 and 10 mg·kg^-1) and prototypic opiate antagonist, naloxone (10 mg·kg^-1) on colonic body temperature. In the daytime, the body temperature response profiles of quail treated with morphine were dependent on the initial body temperature of the bird. In those birds with the lower daytime body temperatures, morphine caused an initial hyperthermic response that was followed by a hypothermia and then a weak hyperthermia; whereas, in birds with the higher initial body temperatures there was a pronounced hypothermia followed by a marked hyperthermia. At night, morphine induced a hyperthermic response in all quail that was followed by a hypothermia. These effects of morphine were blocked by naloxone, with naloxone by itself significantly decreasing the daytime temperature of those quail with the higher initial body temperature. Naloxone had no significant effects on the nighttime body temperatures of any of the quail. These results show that there are day-night rhythms and individual differences in opiate sensitivity and modulation of body temperature in male quail. These findings also suggest that endogenous opioid systems are involved in either the generation and/or expression of the day-night rhythm of body temperature in quail.Abbreviations LD light-dark - T _L low initial body temperatures - T _H high initial body temperatures     

The effect of temperature on growth characteristics and competitions of <Emphasis Type="Italic">Microcystis aeruginosa</Emphasis> and <Emphasis Type="Italic">Oscillatoria mougeotii</Emphasis> in a shallow,eutrophic lake simulator system

Blue-green algal blooms formed by Microcystis and Oscillatoria often occur in shallow eutrophic lakes, such as Lake Taihu (China) and Lake Kasumigaura (Japan). Growth characteristics and competitions between Microcystis aeruginosa and Oscillatoria mougeotii were investigated using lake simulator systems (microcosms) at various temperatures. Oscillatoria was the superior competitor, which suppressed Microcystis, when temperature was <20°C, whereas the opposite phenomenon occurred at 30°C. Oscillatoria had a long exponential phase (20 day) and a low growth rate of 0.22 day⁻¹ and 0.20 day⁻¹ at 15°C and 20°C, respectively, whereas Microcystis had a shorter exponential phase (2–3 days) at 30°C and a higher growth rate (0.86 day⁻¹). Interactions between the algae were stronger and more complex in the lake simulator system than flask systems. Algal growth in the lake simulator system was susceptible to light attenuation and pH change, and algae biomasses were lower than those in flasks. The outcome of competition between Microcystis and Oscillatoria at different temperatures agrees with field observations of algal communities in Lake Taihu, indicating that temperature is a significant factor affecting competition between Microcystis and Oscillatoria in shallow, eutrophic lakes.     

Functional Response ofColeomegilla maculata(Coleoptera: Coccinellidae) to Colorado Potato Beetle Eggs (Coleoptera: Chrysomelidae)

A comparative study of the functional response ofColeomegilla maculataDeGeer (Coleoptera: Coccinellidae) fourth instars was conducted under laboratory, greenhouse, and field conditions. In the laboratory, individual larvae were placed in 9-cm petri dishes for 24 h, with 1, 3, 5, or 7 Colorado potato beetle (Leptinotarsa decemlineata[Say]) (Coleoptera: Chrysomelidae) egg masses. Each egg mass was standardized at 15 eggs. In the greenhouse and field,C. maculatalarvae were provided with an equivalent of 0.5 to 35L. decemlineataegg masses/m²of potato leaf. Fourth instars ofC. maculataexhibited a type II functional response toL. decemlineataeggs under laboratory, greenhouse, and field conditions. Predator search efficiency was inversely related with prey density. The maximum mean attack rate (8.7 eggs) byC. maculatalarvae in the field was about half the mean attack rate in the laboratory (17.6 eggs) and greenhouse (20.1 eggs). The difference in prey density between the laboratory and field seems to have been a major contributing factor in determining the rate of predation, whereas differences in environmental conditions (e.g., temperature and possible alternate food) may explain the differences observed in the predation rate in the greenhouse and field.     

Prey preference and feeding capacity of the larvae ofAblattaria arenaria [Coleoptera: Silphidae], a snail predator

The larval stages ofAblattaria arenaria were provided with 4 different snail species:Monacha syriaca (Ehrenberg),Xeropicta derbentina (Krynicki),Candidula sp., andZebrina eburnea (Pfeiffer) to determine if the prey species affected developmental time and food preference of larvae. Functional response of each larval stage ofA. arenaria was also tested for increasing density ofX. derbentina, the most common prey species found in association withA. arenaria locally. The developmental time of each larval stage did not show any statistical difference when fed with different snail species. The total developmental time from egg hatch to adult emergence was 19.0, 19.1, 18.0 and 21.4 days for prey speciesM. syriaca, X. derbentina, Candidula sp., andZ. eburnea, respectively. When prey was offered to larvae either as a single species or as combination of several species,M. syriaca was the most preferred. The prey least consumed wasCandula sp. when prey was given separately, andZ. eburnea was least preferred when other prey species were present in the arena. The 3^rd larval stage did not eat anyZ. eburnea if other prey species were present. The amount of prey consumed by the 1^st larval stage did not show any statistical differences with increasing density ofX. derbentina. But the response of 2^nd and 3^rd larval stages was very similar to each other although the amount of prey they consumed was very different. They both showed a rapid increase in consumption rate at early densities, then a negatively but slowly accelerated rise to plateaus at higher densities, a type-2 functional response curve. All larval stages were very sensitive to starvation. Mortality started after the 2^nd day, and all individuals of all larval stages were dead by the 5^th day.      

A simple method to preserve algal spores of <Emphasis Type="Italic">Ulva</Emphasis> spp. in cold storage with ampicillin

Preservation of algal spores of the green seaweed Ulva fasciata and U. pertusa was enhanced by the addition of ampicillin in f/2 medium at 4°C. The viability of preserved spores was determined by a spore germination assay at various time intervals. The germination rate of U. fasciata remained at 5% to 38% for the first five days, dropping to 1% to 6% on the 10th day of storage with various preservation treatments without ampicillin at 4°C during parameter-selecting experiments. In f/2 medium, 53% of U. fasciata spores were still viable on day 5 and 23% on day 10 at 4°C. By adding 100 μg mL⁻¹ ampicillin to f/2 medium, 90% of the spores were viable at day 40 and 61% after 100 days of storage at 4°C. Spores of U. pertusa had lower preservation rates, with viabilities of 70% at day 40 and 32% at day 100. Algal spore preservation was heavily dependent on the bacterial contamination and subsequent degradation in stock solutions. Handling editor: L. Naselli-Flores     

A positive fever response in Agama agama and Sceloporus orcutti (Reptilia: Agamidae and iguanidae)

Summary Three species of lizards (Agama agama, Mabuya perrotetii, and Sceloporus orcutti) were tested for a possible increase in mean selected body temperature (MSBT) in response to intraperitoneal injection of alcohol-killed Aeromonas sobria, a gram-negative bacterium known to be pathogenic to reptiles. A paired experimental design was utilized in which each animal was given an injection of sterile saline and 1 · 10¹⁰ A. sobria. Body temperatures were monitored via indwelling cloacal thermocouples at 4-min intervals for one 12-h light period under saline injection and for two consecutive 12-h light periods under bacteria injection. Agama agama demonstrated a significant increase in MSBT on both day 1 and day 2 of bacteria injection with increases of 2.7 and 2.3°C, respectively. The latency period on day 1 averaged 6.4 h. Sceloporus orcutti demonstrated a significant decrease in MSBT on day 1 of bacteria injection and a significant increase in MSBT of 1.0°C on day 2 of bacteria injection. No fever was evident in S. orcutti until the beginning of day 2. Mabuya perrotetii did not exhibit a significant change in MSBT on either day 1 or day 2 of bacteria injection. Agama agama (family Agamidae) is the first Old World reptile to exhibit a fever response to bacteria injection, and with these results fever has now been demonstrated in the lizard families Agamidae, Iguanidae, and Teiidae.Abbreviations MSBT mean selected body temperature - T _b body temperature     

The thermal and energetic significance of clustering in the speckled mousebird,Colius striatus

Summary The effect of clustering behaviour on metabolism, body temperature, thermal conductance and evaporative water loss was investigated in speckled mousebirds at temperatures between 5 and 36°C. Within the thermal neutral zone (approximately 30–35 °C) basal metabolic rate of clusters of two birds (32.5 J·g^-1·h^-1) and four birds (28.5 J·g^-1·h^-1) was significantly lower by about 11% and 22%, respectively, than that of individuals (36.4 J·g^-1·h^-1). Similarly, below the lower critical temperature, the metabolism of clusters of two and four birds was about 14% and 31% lower, respectively, than for individual birds as a result of significantly lower total thermal conductance in clustered birds. Body temperature ranged from about 36 to 41°C and was positively correlated with ambient temperature in both individuals and clusters, but was less variable in clusters. Total evaporative water loss was similar in individuals and clusters and averaged 5–6% of body weight per day below 30°C in individuals and below 25°C in clusters. Above these temperatures total evaporative water loss increased and mousebirds could dissipate between 80 and 90% of their metabolic heat production at ambient temperatures between 36 and 39°C. Mousebirds not only clustered to sleep between sunset and sunrise but were also observed to cluster during the day, even at high ambient temperature. Whereas clustering at night and during cold, wet weather serves a thermoregulatory function, in that it allows the brrds to maintain body temperature at a reduced metabolic cost, clustering during the day is probably related to maintenance of social bonds within the flock.Abbreviations BMR basal metabolic rate - bw body weight - C _totab total thermal conductance - EWI evaporative water loss - M metabolism - RH relative humidity - T _a ambient temperature - T _b body temperature - T _ch chamber temperature - T _cl cluster temperature - TEWL total evaporative water loss - LCT lower critical temperature - TNZ thermal neutral zone     

Effect of temperature on the functional response of Adalia bipunctata to Myzus persicae

The effect of temperature on the functional response of female adults of the two-spot ladybird, Adalia bipunctata L. (Coleoptera: Coccinellidae) was examined in petri dish arenas containing sweet pepper leaves infested with different densities of the green peach aphid, Myzus persicae (Sulzer) (Hemiptera: Aphididae). The predator showed a type II functional response at three tested temperatures ranging from 19°C to 27°C. The theoretical maximum number of prey captured by the predator increased with temperature. Based on the random predator equation, the estimated attack rates ranged from 0.13 h^?1 at 19°C to 0.35 h^?1 at 27°C on a leaf area of 20–25 cm². There was no significant difference between the attack rates of the predator at 23°C and 27°C. Handling time significantly decreased as temperature increased from 19°C (0.39 h) to 27°C (0.24 h). This study shows that A. bipunctata displays high predation rates on M. persicae for a wide range of temperatures, indicating its potential for augmentative releases against this aphid pest. The limitations of the predictions generated by functional response experiments are discussed.     

Functional response ofChrysopa carnea [Neur: Chrysopidae] larvae feeding onHeliothis virescens [Lep.: Noctuidae] eggs on cotton in field cages

The functional response of 3rd instarChrysopa carnea (Stephens) larvae feeding on 4 densities ofHeliothis virescens (F.) eggs was determined on caged cotton (Gossypium hirsutum L.).C. carnea larvae had a mean search rate of 1.08×10⁻⁵ ha/predator-day or 0.11 row-m/predator-day.      

Reduction of metabolic rate and thermoregulation during daily torpor

Physiological mechanisms causing reduction of metabolic rate during torpor in heterothermic endotherms are controversial. The original view that metabolic rate is reduced below the basal metabolic rate because the lowered body temperature reduces tissue metabolism has been challenged by a recent hypothesis which claims that metabolic rate during torpor is actively downregulated and is a function of the differential between body temperature and ambient temperature, rather than body temperature per se. In the present study, both the steady-state metabolic rate and body temperature of torpid stripe-faced dunnarts, Sminthopsis macroura (Dasyuridae: Marsupialia), showed two clearly different phases in response to change of air temperature. At air temperatures between 14 and 30°C, metabolic rate and body temperature decreased with air temperature, and metabolic rate showed an exponential relationship with body temperature (r ²=0.74). The Q ₁₀ for metabolic rate was between 2 and 3 over the body temperature range of 16 to 32°C. The difference between body temperature and air temperature over this temperature range did not change significantly, and the metabolic rate was not related to the difference between body temperature and air temperature (P=0.35). However, the apparent conductance decreased with air temperature. At air temperatures below 14°C, metabolic rate increased linearly with the decrease of air temperature (r ²=0.58) and body temperature was maintained above 16°C, largely independent of air temperature. Over this air temperature range, metabolic rate was positively correlated with the difference between body temperature and air temperature (r ²=0.61). Nevertheless, the Q ₁₀ for metabolic rate between normothermic and torpid thermoregulating animals at the same air temperature was also in the range of 2–3. These results suggest that over the air temperature range in which body temperature of S. macroura was not metabolically defended, metabolic rate during daily torpor was largely a function of body temperature. At air temperatures below 14°C, at which the torpid animals showed an increase of metabolic rate to regulate body temperature, the negative relationship between metabolic rate and air temperature was a function of the differential between body temperature and air temperature as during normothermia. However, even in thermoregulating animals, the reduction of metabolic rate from normothermia to torpor at a given air temperature can also be explained by temperature effects.Abbreviations BM body mass - BMR basal metabolic rate - C apparent conductance - MR metabolic rate - RMR resting metabolic rate - RQ respiratory quotient - T _a air temperature - T _b body temperature - T _lc lower critical temperature - T _tc critical air temperature during torpor - TMR metabolic rate during torpor - TNZ thermoneutral zone - T difference between body temperature and air temperature - VO₂ rate of oxygen consumption     

Observations on future sea level changes in the Venice lagoon

The identification of the environmental conditions inducing different ecophysiological responses in the different strains and populations of the brine shrimp Artemia should improve the understanding of their biogeographic distribution. Nauplii from two Argentinean brine shrimp populations, Artemia persimilis from Salinas Grandes de Hidalgo (province of La Pampa) and Artemia franciscana from Laguna Mar Chiquita (province of Cordoba), were grown up until adulthood at different salinities (30, 60, 90, 120 gL⁻¹) and temperatures (12, 21, 28°C). The aim was to assess the effects of these different conditions on prereproductive life span and reproductive traits. Results evidenced that at 21 and 28°C, at any salinity, A. franciscana from Laguna Mar Chiquita attained higher survival and fecundity, after a shorter prereproductive period, than A. persimilis from Salinas Grandes de Hidalgo. These data support that A. franciscana, considered a superspecies, exhibits higher phenotypic plasticity than A. persimilis, and that A. persimilis is better adapted to lower temperatures than A. franciscana. These differences in temperature and salinity tolerance could explain the present distribution of these two species in the South Cone in South America. Handling Editor: J. Melack     

The relationship between food density and short term assimilation rates in Potamopyrgus antipodarum and Deleatidiumsp.

Much of the variation in individual growth rates can be attributed to differences in individual feeding rates. Therefore, in order to build predictive models of individual, or population growth, the factors influencing an individual's feeding rate must be described. An important determinant of the feeding rate is the relationship between the local abundance of food and the individual's ingestion rate – otherwise known as the functional response. We determined functional responses for two species of invertebrate grazers: the snail Potamopyrgus antipodarum and the mayfly Deleatidium sp., by measuring their assimilation rate with increasing densities of radiolabelled periphyton. The assimilation rates were consistent with the Holling Type II or Michelis Menten functional response curve. The parameters of the functional response yielded estimates of the search area and handling time for the stream invertebrates. Our functional response data indicate that the half-saturation food density for P. antipodarum and Deleatidium sp. were 980 mg and 3200 mg AFDM m^–2, respectively, suggesting that Deleatidium growth may be subject to food limitation more often than is P. antipodarum – despite the lower assimilation efficiency of the latter species.     

Effects of temperature, salinity and irradiance on the growth of the red tide dinoflagellate Gyrodinium instriatum Freudenthal et Lee

The effects of temperature, salinity and irradiance on the growth of the red tide dinoflagellate Gyrodinium instriatum Freudenthal et Lee were examined in the laboratory. Exposed to 45 different combinations of temperature (10–30 °C) and salinity (0–40) under saturating irradiance, G. instriatum exhibited its maximum growth rate of 0.7 divisions/day at a combination of 25 °C and a salinity of 30. Optimum growth rates (>0.5 divisions/day) were observed at temperatures ranging from 20 to 30 °C and at salinities from 10 to 35. The organism could not grow at ≤10 °C. In addition, G. instriatum burst at a salinity of 0 at all temperatures, but grew at a salinity of 5 at temperatures between 20 and 25 °C. It is noteworthy that G. instriatum is a euryhaline organism that can live under extremely low salinity. Factorial analysis revealed that the contributions of temperature and salinity to its growth of the organism were almost equal. The irradiance at the light compensation point (I₀) was 10.6 μmol/(m² s) and the saturated irradiance for growth (I_s) was 70 μmol/(m² s), which was lower than I_s for several other harmful dinoflagellates (90–110 μmol/(m² s)).