Photosynthetic activity of a temperate coral Acropora pruinosa (Scleractinia, Anthozoa) with symbiotic algae in Japan

Physiological properties of the temperate hermatypic coral Acropora pruinosa Brook with symbiotic algae (zooxanthellae) on the southern coast of the Izu Peninsula, Shizuoka Prefecture, central Japan, were compared between summer and winter. Photosynthesis and respiration rates of the coral with symbiotic zooxanthellae were measured in summer and winter under controlled temperatures and irradiances with a differential gasvolumeter (Productmeter). Net photosynthetic rate under all irradiances was higher in winter than in summer at the lower range of temperature (12–20°C), while lower than in summer at the higher range of temperature (20–30°C). The optimum temperature for net photosynthesis was apt to fall with the decrease of irradiance both in summer and winter, whereas it was higher in summer than in winter under each irradiance. At 25/ 50/100 μmol photons nr² s^?1, it was nearly the sea‐water temperature in each season. Dark respiration rate was higher in winter than in summer, especially in the range from 20–30°C. In both seasons the optimum temperature for gross photosynthesis was 28°C under 400 μmol photons nr² s^?1 and lowered with decreasing irradiance up to 22°C under 25 μmol photons nr² s^?1 in summer, while 20°C under the same irradiance in winter. The optimum temperature for production/respiration (P/R) ratio was higher in summer than in winter under each irradiance. Results indicated that metabolism of coral and zooxanthellae is adapted to ambient temperature condition under nearly natural irradiance in each season.     

IMPACT OF BLEACHING STRESS ON THE FUNCTION OF THE OXYGEN EVOLVING COMPLEX OF ZOOXANTHELLAE FROM SCLERACTINIAN CORALS1

Global climate change is leading to the rise of ocean temperatures and is triggering mass coral bleaching events on reefs around the world. The expulsion of the symbiotic dinoflagellate algae is believed to occur as a result of damage to the photosynthetic apparatus of these symbionts, although the specific site of initial impact is yet to be conclusively resolved. Here, the sensitivity of the oxygen evolving complex (OEC) to bleaching stress was studied as well as its natural variation between seasons. The artificial electron donor, diphenyl carbazide (DPC), was added to cultured, freshly isolated and expelled (bleaching treatments only) zooxanthellae suspensions. Chl a fluorescence and oxygen production measurements showed that upon addition of DPC, no restoration of diminished photochemical efficiency occurred under control or bleaching conditions. This result was consistent between 12 h and 5 d bleaching treatments on Pocilloporadamicornis, indicating that the OEC is not the primary site of damage, and that zooxanthellae expulsion from the host is a nonselective process with respect to the functioning of the OEC. Further experiments measuring fast induction curves (FICs) revealed that in both summer and winter, the temperature when OEC function was lost occurred between 7°C and 14°C above the sea surface temperature. FIC and oxygen production measurements of P. damicornis during exposure to bleaching stress demonstrated that the thermotolerance of the OEC increased above the temperature of the bleaching treatment over a 4 h period. This finding indicates that the OEC has the capacity to acclimate between seasons and remains functional at temperatures well above bleaching thresholds.     

Seasonal changes in phagocytic capacity and superoxide anion production of blood phagocytes from tench (Tinca tinca,L.)

Seasonal variations in the ex vivo phagocytic function of blood cells from tench, including ingestion capacity of inert particles and its destruction (microbicide capacity) assessed by measurement of superoxide anion production, were studied. Tench were maintained under natural conditions throughout the year, and the different assays of samples taken during each season were initially performed in vitro at 22°C and the results compared. Subsequently, assays were performed at the same temperature as that of the water ponds in which the fish were kept (“seasonal temperature”: 12°C in winter, 22°C in spring and autumn and 30°C in summer) and the results compared seasonally. The results at 22°C showed that phagocytic capacity was greatest in spring and summer and lowest in winter. However, when phagocytic capacity was measured at seasonal temperature, highest values appeared in winter and lowest in summer and autumn. Nitroblue tetrazolium reduction by tench phagocytes after phagocytosing latex beads demonstrated a similar seasonal behaviour at both 22°C in each season and at seasonal temperature. The highest values appeared in summer, which suggests a better microbicide capacity in this season. The results obtained in this study suggest that for a correct interpretation of ex vivo phagocytic capacity of fish through the year it is necessary to use the same assay temperature as that of the water in which the fish is kept.     

BROAD THERMAL TOLERANCE OF THE SYMBIOTIC DINOFLAGELLATE SYMBIODINIUM MUSCATINEI (DINOPHYTA) IN THE SEA ANEMONE ANTHOPLEURA ELEGANTISSIMA (CNIDARIA) FROM NORTHERN LATITUDES1

The sea anemone Anthopleura elegantissima (Brandt) hosts two species of symbiotic dinoflagellates, known as zooxanthellae, which coexist within the host at southern latitudes only. One of these species, Symbiodinium muscatinei LaJeunesse et Trench, has a broad latitudinal distribution, occurring in intertidal anemones from Washington state to Southern California. To investigate whether high thermal tolerance contributes to the ability of S. muscatinei to inhabit anemones from northern and southern regions, the upper thermal tolerance limit for photosynthesis of symbionts in northern (48°24′ N) populations of A. elegantissima was determined by subjecting anemones to a gradual increase in temperature from 12°C to 30°C over a 10‐week period. Light‐saturated photosynthetic rates of isolated zooxanthellae were the same over the range of 12°C–24°C and declined significantly at 26°C, which is 14°C and 5°C above average summertime seawater temperatures in northern Puget Sound and Southern California, respectively. At 28°C, zooxanthellae isolated from the anemones, and those expelled by their hosts, exhibited extremely low rates of photosynthesis and highly reduced chl content. The photosynthetic rates and chl content of expelled zooxanthellae were lower than those of retained zooxanthellae. The high thermal tolerance of S. muscatinei isolated from northern populations of anemones supports the broad latitudinal distribution of this symbiont, allowing it to coexist with S. californium (#383, Banaszak et al. 1993 ) in southern populations of anemones.     

The role of symbiotic dinoflagellates in the temperature-induced bleaching response of the subtropical sea anemone Aiptasia pallida

Coral bleaching involves the loss of symbiotic dinoflagellates (zooxanthellae) from reef corals and other cnidarians and may be a stress response of the host, algae or both. To determine the role of zooxanthellae in the bleaching process, aposymbiotic sea anemones from Bermuda (Aiptasia pallida) were infected with symbionts from other sea anemones (Aiptasia pallida from Florida, Bartholomea annulata and Condylactis gigantea). The expulsion of algae was measured during 24-h incubations at 25, 32 and 34 degrees C. Photosynthetic rates of freshly isolated zooxanthellae were also measured at these temperatures. The C. gigantea (Cg) symbionts were expelled in higher numbers than the other algae at 32 degrees C. Photosynthesis by the Cg algae was completely inhibited at this temperature, in contrast to the other symbionts. At 34 degrees all of the symbionts had increased expulsion rates, and at this temperature only the symbionts from Florida A. pallida exhibited any photosynthesis. These results provide the first evidence that the differential release of symbionts from the same host species is related to decreased photosynthesis at elevated temperatures, and support other findings suggesting that zooxanthellae are directly affected by elevated temperatures during bleaching events.     

Effect of Temperature Variations on Vermicomposting of Household Solid Waste and Fecundity of Eisenia fetida

Experiments were conducted in winter (October to January) and summer (May to August) seasons to study the effect of seasonal temperature variations on the vermicomposting of household waste using Eisenia fetida earthworms. The prevailing temperatures during experiments were in the range of ?2.7°C to 35.0°C during winter season and 18.0°C to 44.4°C during summer season. Organic matter degradation was higher during winter than summer season. The electrical conductivity (EC) of vermicomposts was increased in the range of 2.3–7.8% in winter season; however, the increase in EC was 0.9–1.8% during summer season for different waste mixtures. There was about 56.2–80% increase in total Kjeldahl nitrogen (TKN) content during winter season, whereas the TKN increase was 23.9–44% during summers. The C:N ratio also decreased remarkably in all the waste mixtures during vermicomposting in both the seasons. However, the C:N ratio reduction was more significant during winter (47–60%) than in summer (31–44%). After the observation period, the net worm biomass achieved was higher during winter than summer season. The temperature variations during winter supported the life activities of earthworms more favourably than in summer. The results indicated that growth and reproductive potential of the earthworms were affected not only by the quality and quantity of the feed but also by ambient temperature.     

Photosynthesis and water relations of well-watered orange plants as affected by winter and summer conditions

The aim of this study was to evaluate how the summer and winter conditions affect the photosynthesis and water relations of well-watered orange trees, considering the diurnal changes in leaf gas exchange, chlorophyll (Chl) fluorescence, and leaf water potential (Ψ) of potted-plants growing in a subtropical climate. The diurnal pattern of photosynthesis in young citrus trees was not significantly affected by the environmental changes when compared the summer and winter seasons. However, citrus plants showed higher photosynthetic performance in summer, when plants fixed 2.9 times more CO₂ during the diurnal period than in the winter season. Curiously, the winter conditions were more favorable to photosynthesis of citrus plants, when considering the air temperature (< 29 °C), leaf-to-air vapor pressure difference (< 2.4 kPa) and photon flux density (maximum values near light saturation) during the diurnal period. Therefore, low night temperature was the main environmental element changing the photosynthetic performance and water relations of well-watered plants during winter. Lower whole-plant hydraulic conductance, lower shoot hydration and lower stomatal conductance were noticed during winter when compared to the summer season. In winter, higher ratio between the apparent electron transport rate and leaf CO₂ assimilation was verified in afternoon, indicating reduction in electron use efficiency by photosynthesis. The high radiation loading in the summer season did not impair the citrus photochemistry, being photoprotective mechanisms active. Such mechanisms were related to increases in the heat dissipation of excessive light energy at the PSII level and to other metabolic processes consuming electrons, which impede the citrus photoinhibition under high light conditions.     

Seasonal variations in basal metabolic rate, lower critical temperature and responses to temporary starvation in the arctic fox (Alopex lagopus) from Svalbard

Metabolic rates of four resting, post-absorptive male adult summer- and winter-adapted captive arctic foxes (Alopex lagopus) were recorded. Basal metabolic rates (BMR) varied seasonally with a 36% increase from winter to summer, while body mass was reduced by 17% in the same period. The lower critical temperature (T _1c) of the winter-adapted arctic fox was estimated to −7°C, whereas T _lc during summer was 5°C. The similarity of these values, which are much higher than hitherto assumed (e.g. Scholander et al. 1950b), is mainly due to a significantly (P<0.05) lower BMR in winter than in summer. Body core (stomach) temperature was stable, even at ambient temperatures as low as −45°C, but showed a significant (P<0.05) seasonal variation, being lower in winter (39.3±0.33°C) than in summer (39.8±0.16°C). The thermal conductivity of arctic fox fur was the same during both seasons, whereas the thermal conductance in winter was lower than in summer. This was reflected in an increase in fur thickness of 140% from summer to winter, and in a reduced metabolic response to ambient temperatures below T _lc in winter. Another four arctic foxes were exposed to three periods of forced starvation, each lasting 8 days during winter, when body mass is in decline. No significant reduction in mass specific BMR was observed during the exposure to starvation, and respiratory quotient was unchanged at 0.73±0.02 during the first 5 days, but dropped significantly (P<0.05) to 0.69±0.03 at day 7. Locomotor activity and body core (intraperitoneal) temperature was unaltered throughout the starvation period, but body mass was reduced by 18.5±2.1% during these periods. Upon re-feeding, locomotor activity was significantly (P<0.05) reduced for about 6 days. Energy intake was almost doubled, but stabilised at normal levels after 11 days. Body mass increased, but not to the level before the starvation episodes. Instead, body mass increased until it reached the reduced body mass of ad libitum fed control animals. This indicates that body mass in the arctic fox is regulated according to a seasonally changing set point.     

Energetics and water flux of the marbled velvet gecko (Oedura marmorata) in tropical and temperate habitats

The gecko Oedura marmorata was studied in two different climatic zones: the arid zone of central Australia and in the wet-dry tropics of northern Australia. Doubly labelled water was used to measure field metabolic rate (FMR) and water flux rates of animals in the field during the temperate seasons of spring, summer and winter, and during the tropical wet and dry seasons. FMRs were highest in the tropical wet season and lowest in the temperate winter. The geckos in central Australia expended less energy than predicted for a similarly sized iguanid lizard, but geckos from the tropics expended about the same amount of energy as predicted for an iguanid. Water flux rates of geckos from the arid zone were extremely low in all seasons compared to other reptiles, and although water flux was higher in tropical geckos, the rates were low compared to other tropical reptiles. The standard metabolic rates (SMRs) of geckos were similar between the two regions and among the seasons. Geckos selected higher body temperatures (T _bs) in a laboratory thermal gradient in the summer (33.5°C) and wet (33.8°C) seasons compared to the winter (31.7°C) and dry (31.4°C) seasons. The mean T _bs selected in the laboratory thermal gradient by geckos from the two regions were not different at a given time of year. The energy expended during each season was partitioned into components of resting metabolism, T _b and activity. Most of the energy expended by geckos from central Australia could be attributed to the effects of temperature on resting lizards in all three seasons, but the energy expended by tropical geckos includes a substantial component due to activity during both seasons. This study revealed variability in patterns of ecological energetics between populations of closely related geckos, differences which cannot be entirely attributed to seasonal or temperature effects. Received: 14 November 1997 / Accepted: 4 May 1998     

The influence of irradiance on the severity of thermal bleaching in sea anemones that host anemonefish

Entacmaea quadricolor is a geographically widespread species of sea anemone that forms a three-way symbiosis with anemonefish and Symbiodinium. This species dominates the reef substrata at North Solitary Island, Australia, which is located in a region identified as a climate change hot spot. Their geographic location places these anemones under significant threat from rising ocean temperatures, although their upper thermal limit and risk of bleaching are unknown. To address this knowledge gap, anemones were exposed to one of four temperatures (23, 25, 27, or 29°C) and one of two irradiance treatments (high or low light) over 6 days. At moderate temperatures (27°C, 1°C above summer average), anemone bleaching was characterised by symbiont expulsion, while extreme temperatures (29°C) resulted in an additional loss of photosynthetic pigments from within symbionts, and in some cases, host mortality. Irradiance influenced the susceptibility to thermal stress with high light promoting the bleaching response, along with significant reductions in the effective quantum yield of anemone symbionts. The long-term loss of photosystem II photochemical efficiency within in hospite symbionts was observed during exposure to temperatures exceeding the summer average, indicating photosynthetic damage. The resident Symbiodinium, identified as clade C using 28S rRNA gene sequences, therefore represents the partner within the symbiosis that is likely to be most vulnerable to rising seawater temperatures. Results suggest that E. quadricolor is living within approximately 1°C of the upper thermal maximum at the Solitary Islands, and given the predictions for rising seawater temperature on Australia’s east coast, the thermal threshold at which bleaching will occur is expected to be reached and exceeded more frequently in the future.     

Effects of temperature, light and heterotrophy on the growth rate and budding of the temperate coral Cladocora caespitosa

Recent investigations have shown the temperate scleractinian coral Cladocora caespitosa to be a new potential climate archive for the Mediterranean Sea. Whilst earlier studies have demonstrated a seasonal variation in growth rates, they were unable to distinguish which environmental parameter (light, temperature, or food) was influencing growth. In this study, the effect of these three factors on the coral physiology and calcification rate was characterized to aid the correct interpretation of skeletal trace element variations. Two temperatures (13 and 23°C), irradiances (50 and 120 μmol m⁻² s⁻¹), and feeding regimes (unfed and fed with nauplii of Artemia salina) were tested under controlled laboratory conditions on the growth, zooxanthellae density, chlorophyll (chl) content, and asexual reproduction (budding) of C. caespitosa during a 7-week factorial experiment. Unlike irradiance, which had no effect, high temperature and food supply increased the growth rates of C. caespitosa. The effect of feeding was however higher for corals maintained at low temperature, suggesting that heterotrophy is especially important during the cold season, and that temperature is the predominant factor affecting the coral’s growth. At low temperature, fed samples had higher zooxanthellae density and chl content, possibly for maximizing photosynthetic efficiency. Sexual reproduction investment of C. caespitosa was higher during favourable conditions characterised by high temperatures and zooplankton availability.     

Comparative effect of live food and manured treatments on water quality and production of ornamental carp, Cyprinus carpio var. koi L., during winter, summer, monsoon and post-monsoon growout experiments in concrete tanks

Four growth trials (each of 11 weeks duration) were conducted during different seasons throughout 1 year, namely, winter, summer, monsoon and post‐monsoon to assess the seasonal influence on growth and production of koi carp, Cyprinus carpio var. koi L. larvae in concrete tanks maintained under different management regimes. Individual weight gain, survival rate, fish deformities and number of marketable fish in each season were compared among four management regimes: (i) carp larvae fed with live zooplankton (LF); (ii) direct fertilization with poultry manure (PM); (iii) direct fertilization with cow dung (CD); and (iv) a control system (C), where a commercial diet containing 32% crude protein was applied. There were three replicates for each treatment. The LF treatment produced significantly higher weight gain, survival rate and number of marketable fish in all seasons (P < 0.05), compared with the other treatments, through maintenance of better water quality and greater abundance of zooplankton in the system. Fish deformities were highest in the C treatment in every season (P < 0.05). Water temperatures averaged 18.6°C (winter), 29.7°C (summer), 28.3°C (monsoon), and 26.5°C in the post‐monsoon trial. Average weight gain of koi carp achieved during the winter trial (2.01 g in C to 4.44 g in LF) was considerably lower than that achieved in the summer, monsoon or post‐monsoon trials. Survival rates of carp ranged from 70.5% (C) to 95.5% (LF) in the winter trial, and were considerably lower than the other seasons. The number of marketable fish was also lowest during the winter trial.     

Energy reserves during food deprivation and compensatory growth in juvenile roach: the importance of season and temperature

The effect of 21 days of starvation, followed by a period of compensatory growth during refeeding, was studied in juvenile roach Rutilus rutilus during winter and summer, at 4, 20 and 27° C acclimation temperature and at a constant photoperiod (12L : 12D). Although light conditions were the same during summer and winter experiments and fish were acclimated to the same temperatures, there were significant differences in a range of variables between summer and winter. Generally winter fish were better prepared to face starvation than summer fish, especially when acclimated at a realistic cold season water temperature of 4° C. In winter, the cold acclimated fish had a two to three‐fold larger relative liver size with an approximately double fractional lipid content, in comparison to summer animals at the same temperature. Their white muscle protein and glycogen concentration, but not their lipid content, were significantly higher. Season, independent of photoperiod or reproductive cycle, was therefore an important factor that determined the physiological status of the animal, and should generally be taken into account when fish are acclimated to different temperature regimes. There were no significant differences between seasons with respect to growth. Juvenile roach showed compensatory growth at all three acclimation temperatures with maximal rates of compensatory growth at 27° C. The replenishment of body energy stores, which were utilized during the starvation period, was responsible for the observed mass gain at 4° C. The contribution of the different energy resources (protein, glycogen and lipid) was dependent on acclimation temperature. In 20 and 27° C acclimated roach, the energetic needs during food deprivation were met by metabolizing white muscle energy stores. While the concentration of white muscle glycogen had decreased after the fasting period, the concentrations of white muscle lipid and protein remained more or less constant. The mobilization of protein and fat was revealed by the reduced size of the muscle after fasting, which was reflected in a decrease in condition factor. At 20° C, liver lipids and glycogen were mobilized, which caused a decrease both in the relative liver size and in the concentration of these substrates. Liver size was also decreased after fasting in the 4° C acclimated fish, but the substrate concentrations remained stable. This experimental group additionally utilized white muscle glycogen during food deprivation. Almost all measured variables were back at the control level within 7 days of refeeding.     

Population dynamics of zooxanthellae during a bacterial bleaching event

Each summer 80–90% of the colonies of Oculina patagonica undergo bleaching off the Mediterranean coast of Israel. To investigate fluctuations through a yearly bleaching cycle, monthly measurements of zooxanthella density, mitotic index and chlorophyll-a concentration were conducted. Results showed (1) a significant negative correlation between sea surface temperature (SST) and zooxanthella density; (2) both significantly lower zooxanthella mitotic index and higher chlorophyll-a per zooxanthella content during the bleaching season compared with the non-bleaching period; (3) prior to bleaching, a lag between the peak of zooxanthella density and chlorophyll-a concentration followed by a similar lag during recovery. Zooxanthella density declined significantly between March and May while chlorophyll-a concentration peaked in April, and then declined. Zooxanthella density increased significantly in November while chlorophyll-a concentration increased significantly in January. We conclude that during bacterial bleaching events, zooxanthellae are severely damaged. However, by the time of the following bleaching event the coral tissues regain their “normal” (pre-bleaching) zooxanthella population density.     

Seasonal changes in energetics and torpor patterns in the subtropical blossom-bat Syconycteris australis (Megachiroptera)

Little is known about how animals from tropical and subtropical climates adjust their energy expenditure to cope with seasonal changes of climate and food availability. To provide such information, we studied the thermal physiology, torpor patterns and energetics of the nocturnal blossom-bat (Syconycteris australis 18 g) from a subtropical habitat in both summer and winter. In both seasons, S. australis frequently entered daily torpor at ambient temperatures between 12 and 25°C when food and water were withheld. Unlike patterns observed in temperate animals, mean minimum metabolic rates during torpor were lower in summer (0.47 ± 0.07 ml O₂ g⁻¹ h⁻¹) than in winter (0.75 ± 0.11 ml O₂ g⁻¹ h⁻¹). Body temperatures during torpor were regulated at 19.3 ± 1.0°C in summer and at 23.4 ± 2.0°C in winter. Torpor bout duration was significantly longer in summer (7.3 ± 0.6 h) than in winter (5.5 ± 0.3 h), but in both seasons, bout duration was not affected by ambient temperature. Consequently, average daily metabolic rates were also significantly lower in summer than in winter. Body temperatures and metabolic rates in normothermic bats did not change with season. Our findings on seasonal changes of torpor in this bat from the subtropics are opposite to those made for many species from cold climates which generally show deeper and longer torpor in winter and are often entirely homeothermic in summer. More pronounced torpor in subtropical S. australis in summer may be due to low or unpredictable nectar availability, short nights which limit the time available for foraging, and long days without access to food. Thus, the reversed seasonal response of this subtropical bat in comparison to temperate species may be an appropriate response to ecological constraints. Received: 6 May 1997 / Accepted: 19 October 1997     

Winter ecology of Arctic charr (<Emphasis Type="Italic">Salvelinus alpinus</Emphasis>) and brown trout (<Emphasis Type="Italic">Salmo trutta</Emphasis>) in a subarctic lake,Norway

We studied habitat choice, diet, food consumption and somatic growth of Arctic charr (Salvelinus alpinus) and brown trout (Salmo trutta) during the ice-covered winter period of a subarctic lake in northern Norway. Both Arctic charr and brown trout predominantly used the littoral zone during winter time. Despite very cold winter conditions (water temperature <1°C) and poor light conditions, both fish species fed continuously during the ice-covered period, although at a much lower rate than during the summer season. No somatic growth could be detected during the ice-covered winter period and the condition factor of both species significantly declined, suggesting that the winter feeding rates were similar to or below the maintenance requirements. Also, the species richness and diversity of ingested prey largely decreased from summer to winter for both fish species. The winter diet of Arctic charr <20 cm was dominated by benthic insect larvae, chironomids in particular, and Gammarus lacustris, but zooplankton was also important in December. G. lacustris was the dominant prey of charr >20 cm. The winter diet of brown trout <20 cm was dominated by insect larvae, whereas large-sized trout mainly was piscivorous, feeding on juvenile Arctic charr. Piscivorous feeding behaviour of trout was in contrast rarely seen during the summer months when their encounter with potential fish prey was rare as the small-sized charr mainly inhabited the profundal. The study demonstrated large differences in the ecology and interactions of Arctic charr and brown trout between the winter and summer seasons.     

A simple temperature-based model predicts the upper latitudinal limit of the temperate coral Astrangia poculata

A few hardy ahermatypic scleractinian corals occur in shallow waters well outside of the tropics, but little is known concerning their distribution limits at high latitudes. Using field data on the growth of Astrangia poculata over an annual period near its northern range limit in Rhode Island, USA, we tested the hypothesis that the distribution of this coral is limited by low temperature. A simple model based on satellite sea surface temperature and field growth data at monthly temporal resolution was used to estimate annual net coral growth north and south of the known range limit of A. poculata. Annual net coral growth was the result of new polyp budding above ~10 °C minus polyp loss below ~10 °C, which is caused by a state of torpor that leads to overgrowth by encroaching and settling organisms. The model accurately predicted A. poculata’s range limit around Cape Cod, Massachusetts, predicting no net growth northward as a result of corals’ inability to counteract polyp loss during winter with sufficient polyp budding during summer. The model also indicated that the range limit of A. poculata coincides with a decline in the benefit of associating with symbiotic dinoflagellates (Symbiodinium B2/S. psygmophilum), suggesting that symbiosis may become a liability under colder temperatures. While we cannot exclude the potential role of other coral life history traits or environmental factors in setting A. poculata’s northern range limit, our analysis suggests that low temperature constrains the growth and persistence of adult corals and would preclude coral growth northward of Cape Cod.     

Effects of body mass,temperature, and season on resting metabolism of the nocturnal gecko Hemidactylus flaviviridis

Abstract

The resting metabolic rate (RMR) of Hemidactylus flaviviridis was measured at different temperatures from 20 to 35°C during winter and summer acclimatization. The mass exponent b values ranged between 0.67 and 0.72. Winter-acclimatized geckos of various body masses had significantly lower RMRs than summer-acclimatized geckos only at 20°C. It seems that low thermal sensitivity for summer–acclimatized group may facilitate activity during its active seasons, and high thermal sensitivity between 20 and 25°C for winter–acclimatized group may conserve energy during inactivity in winter.     

Nutritional role of two algal symbionts in the temperate sea anemone Anthopleura elegantissima brandt

The intertidal sea anemone Anthopleura elegantissima in the Pacific Northwest may host a single type of algal symbiont or two different algal symbionts simultaneously: zooxanthellae (Symbiodinium muscatinei) and zoochlorellae (green algae; Trebouxiophyceae, Chlorophyta). A seasonal comparison of zooxanthellate and zoochlorellate anemones showed stable symbiont population densities in summer and winter, with densities of zoochlorellae about 4 times those of zooxanthellae. Photosynthesis-irradiance curves of freshly isolated symbionts show that the productivity (P(max) cell) of freshly isolated zooxanthellae was about 2.5 times that of zoochlorellae during July; comparable rates were obtained in other months. Models of algal carbon flux show that zoochlorellae may supply the host with more photosynthetic carbon per unit anemone biomass than zooxanthellae supply. Zooxanthellate anemone tissue was 2 per thousand ((13)C) and 5 per thousand ((15)N) enriched and zoochlorellate anemone tissue was 6 per thousand ((13)C) and 8 per thousand ((15)N) enriched over their respective symbionts, suggesting that zoochlorellate anemones receive less nutrition from their symbionts than do zooxanthellate individuals. The disparity between predicted contributions from the algal carbon budgets and the stable isotopic composition suggests that short-term measures of algal contributions may not reflect actual nutritional inputs to the host. Isotopic data support the hypothesis of substantial reliance on external food sources. This additional nutrition may allow both algae to persist in this temperate intertidal anemone in spite of differences in seasonal photosynthetic carbon contributions.     

Biology ofCryptolaemus montrouzieri Mulsant [Coccinellidae: Coleoptera] in relation with temperature

The effect of temperature on the developmental duration ofCryptolaemus montrouzieri Mulsant was quantified by deriving a regression equation for each developmental stage as well as the total life cycle. While the duration of life stages was shorter during summer and longer during winter, the optimum constant temperature for maximal development was found to be 30°C. The adult longevity was extended when reared at 20°C than at 30°C and ambient temperature. The longevity of adults was longer when maintained on grape mealybugMaconellicoccus hirsutus (Green) than on honey and when maintained at 20°C. The fecundity of the predator was higher at 30°C than at 20°C. Eventhough the adults could survive at 10°C, the productive capacity was impaired.