The influence of environmental parameters on the bacterial populations of thermal springs in West Bengal, India

The physico-chemical characteristics and the bacterial populations of three thermal springs in West Bengal have been examined. The springs range in temperature from 42^o C (Saubhagya Kund) to 65^o C (Agni Kur.d). The levels of carbonate and bicarbonate alkalinity, total hardness and the ppm of chloride, phosphate and silicate as well of dissolved oxygen were measured at monthly intervals. Estimates of the bacterial populations were obtained from cultures. Water samples incubated at 37^oC for enumeration of mesophilic microbes, at 50^o C for thermo-tolerant bacteria and at 60^o for strict thermophiles. Tests for coliform organisms were carried out at 37^o C and at 50^o C.
All three springs show seasonal variation in their physico-chemical characteristics and in their bacterial populations. The cooler springs have large populations of mesophilic and thermotolerant bacteria but fewer thermophilic types. In the two hot springs (Saubhagya Kund and Swetganga), the differences of mean bacterial populations observed between 37^o and 50"C and between 50^o and 60^o C are highly significant ( P < 0.01), in the third (Agni Kund) the differences are also significant ( P < 0.01) but the population showed a rising trend with the temperature. Of the biotic and abiotic factors which could be involved in the observed seasonal variation in the bacterial populations, only the fluctuations in the phosphate levels were found to show a significant correlation (0.001 < P < 0.01).     

The optics of tsetse fly eyes in relation to their behaviour and ecology

Abstract The visual acuity of two species of tsetse flies, Glossina morsitans morsitans Westw. and Glossina pallidipes Aust., was investigated. Male G. morsitans eyes have an acute zone in the forward region, with large hexagonal lenses (mean minimum diameter, D=33, SE±0.7 μm), relatively small interommatidial angle (Δ(φ=1.08^o) and angular receptive field of individual ommatidia (Δp) of not less than 1.14^o. A narrow band of square lenses, with intermediate diameter and Δφ, merges with smaller hexagonal lenses in the periphery (24±0.7 μm), with relatively large interommatidial angle (Δφ=3.7^o) and small angular receptive field (Δp = c. 1.6^o). G.pallidipes eyes are similar, except that the lenses in the acute zone are larger than those of G.morsitans , in proportion to their larger body size. Female eyes are not significantly different from male eyes, except that they have a narrower region of binocular overlap (maximum for males = 24^o, for females = 18^o). The eye parameter (p=DΔφ) in the acute zone of male G.morsitans = 0.62, and in the peripheral zone = 1.56. These relatively high values are consistent with fast flight, visual detection of drift due to low wind speeds, mating chases and discrimination of cryptic host animals at high light intensities. The extended region of binocular overlap in males may serve as an early warning system of the approach of potential females. From our estimates, tsetse flies ought to be able to detect small objects against the sky c. 30 min before sunrise and after sunset, and to use their peripheral vision perhaps 15 min earlier and later than this.     

Aspects of the ecology of the coral-eating starfish Acanthaster planci

In the central region of the Great Barrier Reef, Acanthaster planci eats its own disk area of coral each day. At the southern end of the reef lagoon populations of A. planci eat substantially less than this amount of coral per day. Branching and plate corals are preferred food species and massive and encrusting forms are rejected while the preferred food species are available. Only when branching and plate forms on a reef have been consumed will A. planci attack massive and encrusting species. On Australian reefs preferred food species form between 70–99% of the coral cover.
On the Great Barrier Reef A. planci spawns in January and juveniles settle in the top 3 m of water on the windward edge of reefs or on isolated patch reefs behind the main reef. Intolerance of wave attack forces the growing starfish to migrate into deeper water. Lateral movements, probably induced by shortage of living coral in deep water, bring the starfish around the ends of the reef to the leeward side. Here they destroy most of the living coral.
It is suggested that the visual impact of A. planci on reefs of the Indo-Pacific region is related to the composition of the coral fauna. Reefs with a high proportion of preferred food species will be severely damaged while those with faunas composed mainly of massive and encrusting forms will not be altered greatly by starfish predation.
Work on larval development of A. planci carried out by Henderson & Lucas, 1971 showed that metamorphosis took place only at water temperatures of 28^o -29^o C. This suggests that the A. planci plague on the Great Barrier Reef will not spread south of latitude 20^o S (29^o C isotherm in January).     

Egg development of the stoneflies Siphonoperla burmeisteri(Chloroperlidae) and Dinocras cepùnalotes(Perlidae)

SUMMARY. 1. The duration of egg incubation ( Y ) in Dinocras cephalotes and Siphonoperla burmeisteri was related to constant temperatures from 4 to 24°C, by the regression equations Y=2382 T ^{− 1, 402}(r²=0.992, P<0.001) and y= 2683 T ^−1.667 ( r ²=0.994, P <0.001), respectively. No diapause was observed in either species.
2. Egg incubation in D. cephaloles was slow and took 784.9±92.7 (mean ± SD) degree days between 12 and 20°C. significantly more than in S. burmeisteri (445±76.17 degree days: t = 7.44. d.f.=13, P <0.001).
3. For D. cephalotes hatching occurred at temperatures between 12 and 24°C, and for S . burmeisteri between 8 and 20°C. The mean volume of the eggs of D. cephalotes was about 5 times greater than that of S. burmeisteri and the mean body lengths of the newly-hatched nymphs were 1.13 mm and 0.95 mm respectively.
4. This study shows that the freshwater fauna of northern Fennoscan- dia also contains species with warm stenotherm eggs. D. cephalotes. which is of a Mediterranean origin (Zwick, 1981a), may exist at the limit of its distribution in northern Fennoscandia.     

Flying mate detection and chasing by tsetse flies (Glossina)

Abstract Male tsetse flies, probably Glossina morsitans morsitans Westw., were video-recorded in the field as they took off and chased other tsetse flies. Chasers responded (took off) to a target fly at a maximum distance of c. 55 cm, when it subtended c. 1.6^o to their eye (–1 foveal ommatidial subtense). Chased targets were always within this range (mean subtense at take-off = 3.2^o) and approaching the chaser. The most significant difference between chased and non-chased targets was in the rate of approach of the target fly in terms of the increase in its image size immediately before the chaser took off ( 21^o s⁻¹), especially as its relative increase (690% s^-1 P< 0.005). No feature of the target's translational velocity, nor any relationship between that and the image size approached this level of significance. Chasers seemed to 'slipstream' their target at c. 20 cm directly behind it, perhaps suggesting target identification by speed matching. Chases were apparently abandoned when the target image shrank from covering at least two of the chaser's foveal ommatidia to covering only one. Parallax-free measurements of flight speeds indicated a preferred, stable mean groundspeed of 4.8±0.1 m s^_1 (SE), at a mean wing-beat frequency of 209±3 Hz.     

Population biology of the crustose red alga Lithophyllum incrustans Phil. Three populations on the east coast of Britain

The distribution of the crustose red alga Lithophyllum incrustans in the British Isles is described. Three populations are analysed demographically, two having age class distributions corresponding to a type III survivorship curve characteristic of populations in which the greatest mortality occurs in the youngest age classes. The more southern of these two populations has a longer generation time (14.2 years) than the more northern (8.5 years). The third and most southern population has an age class distribution dominated by the 6- and 7-year-old categories. There were few sexual thalli (around 3^o,) but they appeared to put more effort into reproduction than the asexual thalli.     

Glinal variation in morphology among eastern populations of the waterstrider, Aquarius remigis Say (Hemiptera: Gerridae)

We examined morphological variation among populations of the stream-dwelling waterstrider, Aquarius remigis. A previous analysis of allozyme variation along a transect from southern Quebec to southern North Carolina revealed two distinct 'types' of A. remigis, north and south of a transition zone in southern New York and northern Pennsylvania. To assess the concordance of morphological and allozyme differentiation, adults were sampled from 15 populations along the original transect, as well as 11 additional populations in New York, Connecticut and New Jersey. Eight measurements of leg and body size were taken of preserved individuals. Univariate and multivariate analyses (multiple regression, PCA, discriminant analysis) reveal significant differentiation between northern and southern populations with a transition zone between latitudes 39^oand 42^onorth. Strong clines within each region and a clear transition between regions support previous suggestions that there are two distinct 'types' of this species in eastern North America. The transition zone, in morphology coincides with that revealed by the allozyme variation, but extends further south. The covariance of allozyme frequency and morphometric traits suggests that differentiation has occurred through vicariance and secondary contact, and that in this system, cladistic and adaptive differentiation are coupled.     

Poikilothermic traits and thermoregulation in the Afrotropical social subterranean Mashona mole-rat (Cryptomys hottentotus darlingi) (Rodentia: Bathyergidae)

When acclaimated for two months at 26 C the social Mashona mole-rat Cryptomys hottentotus darlingi (±S.D.) resting metabolic rate (RMR) of 0·98±0.·14cm²O₂g _-1 h_-1 ( n =21), within a thermal neutral zone (TNZ) of 28 31·5 C ambient temperature (Ta). The body temperature (Tb) of the mole-rat is very low. 33·3±0·5 C, and remained stable between 25 31·5 C ( n =28). Above 33 C. Tb increased to a mean of 34·±0· C (n=28) (Ta range 33 39 C). Below Ta 25 C. Tb showed strong poikilothermic tendencies, with Tb dropping to a mean of 26·8±1·16 C. whereas above Ta25 C. Tb varied in a typically endothermic pattern. The conductance is high 0·19±0·03 cm² O_2g¹ C ¹ (n=28) at the lower limit of thermoneutrality. The mean RMR at 18 C (the lowest Ta tested) was 2·63 ± 0·55 cm³ O₂g ¹ h ¹ (n=7) which is 2·6 times that of the resting metabolic rate in the TNZ.     

Wintering site fidelity and movement patterns of Western Sandpipers Calidris mauri in the San Francisco Bay estuary

Western Sandpipers Calidris mauri are the most numerous shorebird species in the San Francisco Bay estuary during winter. A sample of 106 Western Sandpipers was captured in mist nets and radio-marked with 1-g transmitters to examine their wintering site fidelity and movements. Differences in distances moved, home range extent and core area size were examined by age, sex, season, site, time of day and tide. All birds remained in the south San Francisco Bay region during winter and exhibited strong site fidelity, with a mean home range of 22.0 km² or only 8% of the study area. First-year birds had larger home ranges (26.6 ± 3.6 km²) than adults (17.2 ± 2.5 km²) in winter, but home range sizes of males and females were not significantly different in any period. Home range sizes were similar between seasons, but core areas were smaller in spring (6.3 ± 1.2 km²) than in early (9.6 ± 4.0 km²) or late (11.6 ± 1.6 km²) winter. Movements and home range size were similar for radio-marked birds located during day and night. The high degree of regional and local site fidelity demonstrated that the mixture of natural mud fiats and artificial salt ponds in southern San Francisco Bay provided sufficient resources for large wintering populations of Western Sandpipers.     

Discharge patterns of locust visual interneurones

The spike discharges of the descending contralateral movement detector (DCMD) neurone, and of some smaller visual interneurones (S-units), were recorded in the ventral nerve cord of adult Schistocerca gregaria Forsk., in response to a stationary disc (25^o) or a small spot (0.2^o) stimulus. The discharge rate of each neurone was plotted over a period of 5 s exposure; the total number of spikes in this period was also noted. The DCMD response to the 25^o disc was a high-frequency burst falling off quickly to a low rate; the 0.2^o spot evoked a prolonged discharge with an early peak in rate. In S-units the discharge was prolonged with both targets; the rate rose to an early peak in each case, with a much higher rate for the larger disc. For the DCMD the total number of spikes per stimulus (5 s) was greater for the 0.2^o spot; for S-units it was greater for the 25^o disc. Thus an increase of about 30-fold in the number of ommatidia stimulated resulted in a fall in the total DCMD response to about one-quarter; a similar increase evoked a rise of about 6-fold in the S-unit response. When the 25^o disc was presented at progressively reduced intensities the total spike response of the DCMD rose steadily to a maximum at about 2.9 μ W m^-2; using the same procedure the spike output of S-units, initially high, declined monotonically. The role of inhibition in these results is discussed.     

Seasonal variability in growth of larval Japanese anchovy Engraulis japonicus driven by fluctuations in sea temperature in the Kii Channel, Japan

Seasonal variability in the growth of larval Japanese anchovy Engraulis japonicus was examined through otolith microstructure analysis based on the samples collected from the northern side (inner area, IA) and the southern side (outer area, OA) of the Kii Channel from April 2006 to March 2007. Growth trajectories (otolith backcalculated mean standard length of 5 day intervals from 5 days after hatch to 24 days) as well as the most recent 5 day mean growth rate of larvae before capture ( G ₅) differed among months. Growth trajectories showed the same pattern as G ₅. In IA, mean ± s.d. G ₅ ranged from 0·31 ± 0·04 mm day⁻¹ (January) to 0·73 ± 0·06 mm day⁻¹ (October). In OA, mean ± s.d. G ₅ ranged from 0·36 ± 0·05 mm day⁻¹ (January) to 0·79 ± 0·11 mm day⁻¹ (August). G ₅ values declined from November to January and then started to increase. In general, the seasonal patterns of growth were similar between IA and OA, and a clear seasonal pattern in growth was identified. When the relationships among larval growth rate, sea temperature, zooplankton density and larval density were examined, growth rate was positively related with sea temperature in both areas and not related with the other factors. The similar pattern in growth observed between IA and OA was probably due to the low spatial variability in sea temperature compared to its seasonal variability.     

Thermoregulation in four Australian lizards of the genus Egernia (Sauria: Scincidae)

Mean thermal preferenda for the head and body were found to be similar in Egernia whitei, E. cunninghami, and E. bungana (range in T_H= 33.6^o -33.8^o C; range in T_B= 34.0^o-35.3^oC). However, those for E. majors were significantly lower (T_H= 31.1^o C, T_B=32.9^oC). Significant differences were found between mean head and body preferred temperatures in E. cunninghami and E. major. Higher temperatures were tolerated by the body than the head in all four species. Gaping was not observed to occur prior to cessation of respiration in any of the four species during radiant or solar heating. Based upon thermal preferenda and critical thermal maxima data, thermal safety margins for body temperature were calculated for E. whitei and E. cunninghami Postural orientation to the sun's rays increased and decreased heat gain. The seeking of shade was the most effective method employed by all four species for reducing head and body temperature.     

Biometric analysis of Syngnathus abastev populations

Significant differences (ANOVA) in three out of six meristic characters and in 16 out of 18 morphometric characters were found among Syngnathus abaster caught in the River Danube at sites 900 km upwards from the mouth of the Black Sea, the fresh waters of Ukraine, the Black Sea and the Azov Sea. The Danube populations showed significantly greater values for antedorsal (aD) and anteanal (aA) distances, but considerably smaller values for postdorsal (pD) distance and head length (L_H) than other populations analysed (Tukey-Kramer's test). The relation of total length (L_T) to standard length ( Ls ) for the Danube populations was L_s= 0–97. L_t , the length-mass relationship was M=4.122. L _T^3.63 and the mean ± S.D. of Fulton condition factor was 0.34 ± 0.08.     

Properties of lucerne transient streak virus, and evidence of its affinity to southern bean mosaic virus

A virus obtained from naturally infected lucerne ( Medicago sativa ) in New Zealand reacted with antiserum to an Australian isolate of lucerne transient streak virus (LTSV). Some plants infected with New Zealand isolates showed yellow flecks along lateral veins of leaves; symptoms were transient in some lucerne plants but persistent in others. A New Zealand isolate (LTSV-NZ) infected 14 of 39 plant species tested by mechanical inoculation, but was not transmitted by five aphid species. In sap of Nicotiana clevelandii , LTSV-NZ was infective after storage for 4 wk at 20 ^oC, diluting to 10^-5, or heating for 10 min at 70 ^oC. Purified virus preparations contained a single electrophoretic component and a single sedimenting component (s_20w= 112 S ) which formed a single buoyant density component in CsCl (1.37 g cm^-3) but two density components in Cs₂SO₄ (1.26 and 1.32 g cm^-3). LTSV-NZ particles were stable in 10 ITIM EDTA at pH 5, but not at pH 8, being degraded into two sedimenting components of 105 S and 92 S. Particles contained c. 18% RNA in the form of one single-stranded RNA molecule of mol. wt 1–4 times 10⁶, and a polypeptide of mol. wt c. 32 400. LTSV-NZ was serologically unrelated to 24 other isometric plant viruses. However, its properties are similar to those of southern bean mosaic virus and allied viruses. The present cryptogram of LTSV is R/l: 1–4/(18):S/S:S/*.     

Allozyme Variation and the Genetic Structure of Populations of the Rare Sedge Carex misera (Cyperaceae)

Abstract Carex misera is a rare sedge, endemic to rocky outcrops and mountain summits within the southern Appalachian Mountains from northern Georgia to northern North Carolina. We assessed allozyme diversity for 406 individuals from nine populations over most of the geographic range. Twenty-seven putative loci were assayed and eight (30%) were found to be polymorphic. Nei's gene diversity statistics ( H _T =0.043, H _S =0.019, G _ST =0.551) indicated low levels of variation but relatively highly differentiated populations, suggesting little gene flow. Significant deviations from genotypic expectations under Hardy-Weinberg equilibrium, high positive fixation indices, and the existence of small genetic neighborhoods within populations suggest that at least some inbreeding occurs. Cluster analysis of Nei's genetic identity statistics and principal component analysis of allele frequency data showed high similarity among the six southern populations with the two northern populations more differentiated from them and from each other. These results suggest that preservation of the northern populations is necessary to conserve the already low levels of genetic diversity within the species.     

Some factors influencing the Moroccan distribution of the western Mediterranean spur-thighed tortoise, Testudo graeca graeca L., and those precluding its survival in NW Europe

The Moroccan distribution of Testudo graeca graeca L. is defined by locality records (109) and related to data from nearby or bioclimatically equivalent meteorological stations (86) to produce a rain-temperature climagram. Tortoises attain 1900 m in the High Atlas range. Tortoises occur where mean annual rainfall (P) is up to 1062 mm, and even 1112 mm where mean minimum monthly temperature for the coolest month (m) is below 0^oC and they are usually absent unless associated (90.0%) with Quercus ilex L. and Quercus suber L. woodland. Tortoises are absent from the Arctic-Alpine and Arid or Saharan bioclimates and where, without riverine habitat, Emberger's Quotient (Q) is below 19.5 (P = 139 mm) in the Steppe bioclimate. Below Q_= 39.1, they occur (88.9%) where there is Argania spinosa (L.) Maire woodland in the south-west and other broad-leaved and mixed wood- and scrubland species elsewhere. The Moroccan climagram includes and is extended by further stations (36) in the North African and southern European ranges generally ( T. g. graeca is reported in NW Egypt). The Moroccan range potentially occupies 167 000 m². Of a total of 45 stations below 550 m in NW Europe, the Western Mediterranean climagram only overlaps 12 in more oceanic Britain and Ireland; 11 are coastal or insular and 11 where Quercus woodland extends the natural range with m below 0^oC in montane areas. Tortoises do not occur where mean annual sunshine much exceeds 3250 h in northern Africa or below c. 2400 h in NW Europe. Tortoises introduced from the Mediterranean region by the pet trade are unable to reproduce if they survive in NW Europe for insolation is insufficient for egg incubation and hatchling survival.     

Thermal tolerance of a northern population of striped bass Morone saxatilis

Thermal tolerance of age 0+ year Shubenacadie River (Nova Scotia, Canada) striped bass Morone saxatilis juveniles (mean ± s . e . fork length, L _F, 19·2 ± 0·2 cm) acclimated in fresh water to six temperatures from 5 to 30° C was measured by both the incipient lethal technique (72 h assay), and the critical thermal method ( C _m). The lower incipient lethal temperature ranged from 2·4 to 11·3° C, and the upper incipient lethal temperature ( I _U) from 24·4 to 33·9° C. The area of thermal tolerance was 618° C². In a separate experiment, the I _U of large age 2+ year fish (34·4 ± 0·5 cm L _F) was 1·2 and 0·6° C lower ( P < 0·01) than smaller age 1+ year fish (21·8 ± 0·5 cm L _F) at acclimation temperatures of 16 and 23° C. Using the C _m, loss of equilibrium occurred at 27·4–37·7° C, loss of righting response at 28·1–38·4° C and onset of spasms at 28·5–38·8° C, depending on acclimation temperature. The linear regression slopes for these three responses were statistically similar (0·41; P > 0·05), but the intercepts differed (25·3, 26·0 and 26·5° C; P < 0·01). The thermal tolerance of this northern population appears to be broader than southern populations.     

Hypocholesterolemic effect of Eubacterium coprostanoligenes ATCC 51222 in rabbits

Recently, a unique bacterium, Eubacterium coprostanoligenes ATCC 51222, that reduces cholesterol to coprostanol was isolated. Because coprostanol is absorbed poorly, it was hypothesized that oral administration of Eu. coprostanoligenes might decrease cholesterol concentration in blood because the micro-organisms will decrease the absorption of endogenous and dietary cholesterol by conversion to coprostanol. To test the hypothesis, three adult New Zealand White rabbits received 4 ml of Eu. coprostanoligenes suspension ( ca 2 times 10⁷ cells ml^-1) daily per os for 10 d; three other adult New Zealand White rabbits received the same dosage of boiled bacterial suspension. Plasma cholesterol concentration of experimental rabbits (183.3 ± 11.0 mg dl^-1, mean ± S.E.) was significantly lower ( P < 0.001) than that of controls (248.8 ± 12.3 mg dl^-1, mean ± S.E.). The coprostanol-to-cholesterol ratios in contents of digestive tracts of experimental rabbits were greater than those of controls. The data indicate that oral administration of Eu. coprostanoligenes caused a significant hypocholesterolemic effect in rabbits and that this effect can be explained by the conversion of cholesterol to coprostanol in the intestine.     

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

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

Flight behaviour of tsetse flies in host odour plumes: the initial response to leaving or entering odour

ABSTRACT. Free-flying, wild male and female Glossina pallidipes Aust. and G. m. morsitans Westw. were video-recorded in the field in Zimbabwe as they entered or left the side of a host-odour plume in cross-wind flight, or as they overshot a source of host odour in upwind flight (camera 2.5 m up looking down at a 3 times 2.5 m field of view at ground level). 80% of cross-wind odour leavers turned sharply ( turns 95^o), but without regard to wind direction (overshooters behaved essentially the same except that nearly 100% turned). Many fewer flies entering a plume cross wind turned ( c . 60%), and when they did they made much smaller turns ( 58^o); these turns were, however, significantly biassed upwind ( c . 70%). All three classes of fly had similar groundspeeds ( 5.5–6.5 m s^_1) and angular velocities ( 350–400^o s^-1). Clear evidence was obtained of in-flight sensitivity to wind direction: significantly more flies entering odour turned upwind than downwind, and odour losers turning upwind made significantly larger turns than average. The main basis for the different sizes of turn was the different durations of the turning flight, rather than changes in angular velocity or speed. No evidence was found of flies landing after losing contact with odour.