Copper and zinc in an ecological series of talitroidean Amphipoda (Crustacea)

Summary Cu and Zn concentrations were determined for the following talitroidean amphipods, Hyale nilssoni (Rathke), Talitrus saltator (Montagu), Talorchestia deshayesii (Audouin), Orchestia mediterranea Costa, O. gammarellus (Pallas), O cavimana Heller and Arcitalitrus dorrieni (Hunt) in September 1986 from sites in W. Britain (mostly Scottish). To minimize size effects, only animals >2mg body dry weight were included in analyses. Only Talorchestia (Cu & Zn) and O. cavimana (Zn) showed any residual relationship between metal concentration and dry weight. Log transformed data for concentrations of each metal against log dry wt. in all species were compared by ANCOVA. Copper and zinc concentrations of males and females were not significantly different in O. gammarellus, O. mediterranea and T. deshayesii, though Cu (but not Zn) concentrations differed with sex in O. cavimana. The order of species when ranked according to an ascending series of Cu concentrations (at standard body weight) reflected their ecological zonation from sea to land closely, with species living proximal to the sea having lowest Cu concentrations. The 6 talitrid species all had similar Zn concentrations but the Zn concentration of H. nilssoni was considerably lower. There was a relationship between Cu and Zn concentrations in individuals of only one species (O. gammarellus). Data on Cu and Zn concentrations for O. gammarellus derived from the same site in September 1983 were almost exctly the same as in September 1986. The possible impact of seasonal variation on haemocyanin levels is discussed.     

Variation of the Locomotor Activity Rhythms in Three Species of Talitrid Amphipods,Talitrus saltator,Orchestia montagui,and O. gammarellus,from Various Habitats

The expression of biological rhythms was investigated in five populations of three different species of talitrid amphipods from various habitats in the Maremma Regional Park, Grosseto, Italy: Talitrus saltator (from a sandy beach and a canal), Orchestia montagui (form a Posidonia banquette), and O. gammarellus (from a cave entrance and a river bank). Locomotor activity rhythms were recorded in individual animals over 21 days in constant dark at a temperature of 18°±1°C. A high variability in rhythm expression was evident, not only among species and populations but also within populations and the activity pattern of individuals. Activity rhythms of T. saltator and O. montagui were similar, with a good definition and precise circadian periodicity, whereas O. gammarellus showed a high variability and low definition of the circadian rhythm. Significant differences were also observed between two populations of O. gammarellus and T. saltator from different habitats. Within the O. gammarellus species, a significantly higher percentage of active animals (p<0.001) was observed in the cave than the river‐bank population; within T. saltator, a significantly lower percentage of active animals (p<0.01) and higher percentage of periodic animals (p<0.05) was found in the canal than the sandy beach population. With reference to environmental stability and variability, the differences observed are explained as a need for plasticity to adapt to environmental changes.     

Seasonal variation in copper and zinc concentrations in three talitrid amphipods (Crustacea)

Cu and Zn concentrations were determined for three talitrid amphipods, Orchestia gammarellus (Pallas), O. mediterranea Costa and Talitrus saltator (Montagu), collected at two-monthly intervals in 1987 from sites on Great Cumbrae Island, Firth of Clyde, Scotland. To account for size effects, log transformed Cu and Zn concentrations were regressed against log dry weight for each bimonthly sample of each species, and compared by analysis of covariance. Copper concentrations in O. gammarellus were significantly raised in March 1987, and lowered in November 1987. Copper concentrations in O. mediterranea and T. saltator were significantly lowered in November 1987. Cu concentrations differed interspecifically in the order O. gammarellus > O. mediterranea > T. saltator. There was no significant intraspecific seasonal variation in zinc concentration in any of the three species. Zn concentrations differed interspecifically in the order T. saltator > O. gammarellus > O. mediterranea.     

Locomotor activity patterns of two sympatric species Orchestia montagui and Orchestia gammarellus (Crustacea,Amphipoda)

Freshly adult individuals of two sympatric species, Orchestia gammarellus and Orchestia montagui, collected in spring from the supralittoral zone of Bizerte lagoon (Northern of Tunisia) at Menzel Jemil, were housed in a controlled environment cabinet. Locomotor activity rhythm was recorded in isolated individuals and groups by infrared actograph every 20 min by a data-logger, at a constant temperature of 18 ± 0.5 °C under constant darkness. According to double-plotted actograms and waveform curves, results showed the presence of two different locomotor patterns; in fact, individuals of O. gammarellus concentrated their activity during the hours of subjective night, whereas O. montagui were active during the subjective night and beyond the subjective dawn. Furthermore, whatever the species studied, periodogram analysis indicated a distinct circadian pattern of activity. Moreover, whatever the experiment condition is, the most clearly defined rhythms were found in O. gammarellus. In contrary to O. gammarellus, the group effect on the locomotor rhythm parameters seems to be less marked in O. montagui. On the other hand, a highly inter-individual variability was observed in the activity time for these two species and especially for O. montagui groups.     

Endogenous activity rhythm in Talitrus saltator,Britorchestia brito (Crustacea,Amphipoda) and Tylos europaeus (Crustacea,Isopoda) from Barkoukech Beach (Tabarka,Tunisia)

The locomotor activity rhythm of three supralittoral crustacean species, Tylos europaeus (terrestrial isopod) and Britorchestia brito and Talitrus saltator (amphipod, Talitridea), was investigated in Barkoukech Beach. The rhythm was monitored in individual animals in spring under continuous darkness and constant temperature. Results revealed that whatever the species, actograms and mean activity curves showed that specimens of T. europaeus and T. saltator concentrated their activity during the subjective night; whereas, B. brito concentrated its activity during the subjective day. The three species exhibited a circadian locomotor rhythm with mean circadian period, respectively, equal to 24h41′ ± 0h44′, 24h46′ ± 0h55′ and 25h21′ ± 1h16′. The most stable locomotor rhythm was found in T. saltator (0.444 ± 0.246). Furthermore, individuals of T. europaeus were significantly more active (10h47′ ± 2h52′) than the two amphipods. Differences in the activity patterns of the three species will be discussed as an adaptative strategy to respond to interspecific competitive interactions.     

Influence of environmental conditions on the distribution of Amphipoda,Talitridae, in the lagoon complex of Ghar El Melh (north‐east of Tunisia)

The study of the spatiotemporal distribution of talitrid amphipods was carried out along a transect in three stations belonging to the lagoon complex of Ghar El Melh, namely the supralittoral zones of the old harbour of Ghar El Melh, the opposite to Boughaz and Sidi Ali Mekki lagoon. Four species belonging to Talitridae family with two different genera were identified at all stations. These species are Orchestia gammarellus, Orchestia mediterranea, Orchestia stephenseni and Platorchestia platensis. The first two species were collected during the four seasons. The study of the density showed that the most important global mean density in talitrid was found in the supralittoral zone of opposite to Boughaz. In addition, statistical analysis showed a significant difference in the seasonal distribution of amphipods based on plant associations. Furthermore, the highest diversity of talitrid was observed in the winter in the supralittoral zone of opposite to Boughaz and in summer in the supralittoral zones of Sidi Ali Mekki lagoon and the old harbour of Ghar El Melh. Results showed that at all stations, a highly significant correlation of amphipod community with Cymodocea banquette was observed. Moreover, principal component analysis showed that the distribution of the different species depends on climatic and edaphic factors.     

Effect of age,sex, and mutual interaction on the locomotor behavior of Orchestia gammarellus in the supralittoral zone of Ghar El Melh lagoon (Bizerte,Tunisia)

Freshly collected individuals of Orchestia gammarellus from the supralittoral zone of Ghar El Melh lagoon (Northern of Tunisia) were housed in spring in a controlled-environment cabinet. Locomotor activity rhythm of this species was recorded in spring, at a constant temperature of 18 ± 0.5 °C. In the first experiment, juveniles and adults specimens were kept under light-dark cycle in phase with the natural diel cycle. In the two other experiments (males/females and mixed/unmixed groups), individuals of O. gammarellus were maintained under constant darkness. According to double-plotted actograms, waveforms and periodogram analysis, results revealed different locomotor pattern. However, locomotor rhythm of juveniles was more stable than adults. Also, the locomotor activity rhythm of groups was more defined than that of the isolated individuals. Moreover, the activity of mixed groups as well as unmixed groups was more pronounced than the activity of the isolated individuals. Furthermore, results showed no significant difference between locomotor rhythm pattern of males and females of this species.     

Amphipoda and Isopoda diversity around Tunisian wetlands (North Africa) in relation to environmental conditions

Amphipoda and Isopoda were sampled in 40 Tunisian wetlands, and their fauna were compared at four different types: lagoon, sebkhas, dams and hill reservoir. At each station, eight quadrates of 50 × 50 cm were randomly placed. Amphipoda and Isopoda were collected by hand. They were identified to species level. At each station, analyses of organic matter, sodium, calcium and heavy metals content from the soil collected in each station were performed. We recorded 19 and eight species for respectively Isopoda and Amphipoda and caught 3,035 specimens in total. The highest isopod's species richness (11 species) was noted around hill reservoirs and dams, a quite similar richness in the banks of lagoons (10 species) but only six species in the sebkhas. Eight amphipod species were recorded in the supralittoral zone of lagoons, three species around sebkhas but no amphipods were found in samples from dams and hill reservoirs. Isopod species richness was positively correlated with soil humidity. However, the distribution of the species Orchestia mediterranea, Orchestia gammarellus, Orchestia montagui, Orchestia stephenseni and Platorchestia platensis was related to soil metal concentrations.     

Cultivation of Lemna gibba under desert conditions. I: Twelve months of continuous cultivation in open ponds

Duckweed, Lemna gibba, was grown in 12 m² shallow ponds in the Negev desert, during 12 months of continuous cultivation, beginning April 1984. Average monthly growth rates varied with the season of the year. The lowest daily yield, 2·6±0·4 g dry weight m⁻² day⁻¹, was obtained during January. Highest daily yields, 7·9±2·6 g dry weight m⁻² day⁻¹ and 7·0±1·2 g dry weight m⁻² day⁻¹, were obtained during September and May. A 35% decline of the yield was seen during midsummer (July), 4·8±1·2 g dry weight m⁻² day⁻¹. The average rate for the year was 5·15±1·7 g dry weight m⁻² day⁻¹. The protein content of the plants ranged from 30 to 38% per unit dry weight.Growth performance is discussed in relation to the prevailing climatic conditions.     

COMPARATIVE PHOTOSYNTHESIS OF TWO SPECIES OF INTERTIDAL EPIPHYTIC MACROALGAE ON MANGROVE ROOTS DURING SUBMERSION AND EMERSION

Photosynthesis and dark respiration rates were measured in water and in air, and the capacity to recover photosynthetic activity from emersion stress was examined for two species of intertidal, epiphytic macroalgae—Bostrychia calliptera (Montagne) Montagne and Caloglossa leprieurii (Montagne) J. Agardh—collected on prop roots of the red mangrove Rhizophora mangle L. in Buenaventura Bay, Pacific coast of Colombia. In both species, net photosynthetic rates were significantly higher under submersed conditions. Maximum photosynthetic rates (P_max) in water and in air were highest in B. calliptera, 126 ± 4 versus 52 ± 9 μmol O₂·mg chl a⁻¹·h⁻¹, respectively. In C. leprieurii, P_max of submerged plants in water and in air were 98 ± 9 versus 30 ± 11 μmol O₂·mg chla⁻¹·h⁻¹. The photoinhibition model of Platt et al. (1980) was used to fit the experimental data in both water and air for both species. Photoinhibition occurred at irradiance as low as 200 μmol·m⁻²·s⁻¹. The photosynthesis–light response curves demonstrated an adaptation to shaded habitats for both species, as light compensation points in water and air for both species were below 17 ± 5 μmol·m⁻²·s⁻¹. The rate of dehydration was significantly lower in thalli of B. calliptera compared to C. leprieurii. An increase of photosynthetic activity in B. calliptera was evident between 5% and 15% water loss, but rates decreased thereafter with declining water content. In C. leprieurii, desiccation negatively influenced photosynthetic rates that significantly decreased linearly with declining water content. In B. calliptera, net photosynthesis reached zero only at a water content between 29% and 35%, whereas in C. leprieurii no net photosynthesis occurred in plants containing less than about 50% of their relative water content. Resubmerged plants ofB. calliptera exhibited 100% photosynthetic recovery after 45 min, whereas C. leprieurii recovered 100% at about 120 min. On the basis of the comparison of rates of light-saturated net photosynthesis for B. calliptera in air versus in water, aerial photosynthetic activity ranged from 35% to 42% of that in water, whereas the emersed photosynthetic capacity of C. leprieurii ranged from 24% to 29% of that in water. Using tidal predictions and the emersed photosynthetic rates, a carbon balance model was constructed for both species over a single daylight period. The calculations indicated that emersed photosynthesis increased average daily carbon production of B. calliptera by 17% and C. leprieuri by 12%. The physiological responses to desiccation stress and the photosynthetic recovery capacities between species correlated with, and may determine, their vertical distribution in the mangrove habitats of Buenaventura Bay.     

Ionic regulation and salinity related changes in haemolymph protein in the semi-terrestrial beachflea Orchestia gammarellus (Pallas) (Crustacea: Amphipoda)

• 1.1. Orchestia gammarellus maintained in air and provided with food in the form of agar was found to be very tolerant of changes in the ionic content of the food and was shown to have well-developed powers of ionic regulation over the salinity range 5–40‰ at 10°C.
• 2.2. There was an inverse relationship between haemolymph protein and acclimation salinity.
• 3.3. The concentration of sodium and protein ions in the haemolymph of O. gammarellus from above high water mark (H.W.M.) was markedly different from animals collected below H.W.M. Individuals taken from above H.W.M. characteristically had low haemolymph sodium but elevated haemolymph protein concentrations.

     

A novel thermophilic β-mannanase with broad-range pH stability from Lichtheimia ramosa and its synergistic effect with α-galactosidase on hydrolyzing palm kernel meal

β-Mannanase is the key enzyme in the hydrolysis of mannan which has been widely applied in diverse industrial fields such as biobleaching pulps, food and feed industry, bioethanol and pharmaceutical applications. In this study, a novel GH5 family β-mannanase gene (LrMan5B) with 381 amino acid residues was identified from Lichtheimia ramosa, and highly expressed in Pichia pastoris X33. The amino acid sequence shares the highest identity (64%) with the β-mannanase from Rhizomucor miehei. Purified recombinant LrMan5B showed the optimal activity at pH 5.0 and 65 °C. It had broad-range pH stability (retaining >65% activity after incubation at pH 3.0–8.0 at 37 °C for 24 h) and was highly thermostable (retaining >80% activity after incubation at 60 °C for 30 min). LrMan5B displayed the highest catalytic efficiency for locust bean gum and the k_cat/K_m value was 1357.47 mL·mg⁻¹·s⁻¹, followed by guar gum (512.82 mL·mg⁻¹·s⁻¹), konjac glucomannan (454.21 mL·mg⁻¹·s⁻¹), and palm kernel meal (137.00 mL·mg⁻¹·s⁻¹). In order to evaluate the synergistic effect of LrMan5B and α-galactosidase LrAgal36A from L. ramosa, LrAgal36A was supplemented to hydrolyze palm kernel meal with LrMan5B together, showing that the reducing sugar release significantly increased by 21% (compared with the sum of that by hydrolysis of single Lrman5B or LrAgal36A). Due to its favorable enzymatic properties, LrMan5B might own potential applications in the area of food and feed processing.     

Locomotor activity rhythm of two sympatric species Talitrus saltator (Amphipoda) and Tylos europaeus (Oniscidea) from Tunisian beaches under continuous light

Locomotor activity rhythm of the supralittoral species Talitrus saltator and Tylos europaeus was studied under continuous light in populations of Korba and Barkoukech beaches in summer. Results showed that these two species were characterized by a nocturnal behaviour. Under the subjective night, the activity was continuous for T. saltator and interrupted in T. europaeus with the presence of a clear drift towards the right more accentuated for the second species. Whatever the site, using actograms and the waveforms, results showed the absence of bimodal profile in T. europaeus and the plurimodal one in T. saltator. Moreover, the most important activity peaks were observed around the dawn and the dusk, respectively. Furthermore, periodogram and MESA analyzes highlighted the presence of ultradian and circadian components. Whatever the component and the site, the inter-individual variability was more pronounced in T. europaeus. Moreover, whatever the site, individuals of T. europaeus were more active and the locomotor rhythm was more defined in T. saltator. With reference to environmental stability and variability, the differences of locomotor activity characteristics observed between these two species are explained as a need for plasticity to adapt to environmental changes.     

Egg production of the marine,planktonic copepod,Calanus pacificus Brodsky: Laboratory observations

When acclimated to a continuous, superabundant food supply and constant temperature, Calanus pacificus Brodsky females produce eggs at a weight-specific rate ranging from 0.13 · day^?1 at 8°C to 0.21 · day^?1 at 15°C. Maximum weight-specific egg production rates do not change with seasonal changes in female body size. The relationship between egg production rate and food concentration is hyperbolic, with threshold and critical concentrations that are high relative to other species for which data are available. Food concentration and temperature influence spawning frequency (i.e., the time required for oocytes to mature) much more than the number of eggs in a single spawning event (i.e., clutch size). Clutch size is significantly related to female body size.     

Seasonal variation in trace metal concentrations in three talitrid amphipods from the Gulf of Gdansk, Poland

Talitrid amphipod crustaceans are increasingly being used as biomonitors of trace metal bioavailabilities in coastal waters, and it is important to understand how other factors, in addition to metal pollution, might affect their accumulated body concentrations. Seasonal variation (April-October 2000) in body concentrations of copper, zinc, cadmium, iron, manganese, lead and nickel has been investigated in three species, Orchestia cavimana, Talitrus saltator and Talorchestia deshayesii, from the region of the Gulf of Gdansk (including the Vistula Lagoon), Poland, an area with considerable temperature variation between summer and winter. Seasonal variation in the body metal concentrations of talitrid amphipod crustaceans was confirmed in each population, but only copper showed a consistent pattern. Copper concentrations fell from early to late summer, perhaps either as a result of the replacement of the older overwintering generation by the younger spring one, or as a result of the loss of haemocyanin in autumn amphipods entering a period of low metabolic activity. Metal concentration data for T. saltator from Gdynia-Osada Rybacka compared with equivalent data for 1996 and 1998 show a significant drop in metals associated with the influx of the Vistula river water, which occurred in 1998, following a major flood event in 1997.     

CO2 flux in alpine wetland ecosystem on the Qinghai-Tibetan Plateau, China

Using the CO₂ flux data measured by the eddy covariance method in the northeast of Qinghai-Tibetan Plateau in 2005, we analyzed the carbon flux dynamics in relation to meteorological and biotic factors. The results showed that the alpine wetland ecosystem was the carbon source, and it emitted 316.02 gCO₂ · m⁻² to atmosphere in 2005 with 230.16 gCO₂ · m⁻² absorbed in the growing season from May to September and 546.18 gCO₂ · m⁻² released in the non-growing season from January to April and from October to December. The maximum of the averaged daily CO₂ uptake rates and release rates was (0.45 ± 0.0012) mgCO₂ · m⁻² · s⁻¹ (Mean ± SE) in July and (0.22 ± 0.0090) mgCO₂ · m⁻² · s⁻¹ in August, respectively. The averaged diurnal variation showed a single-peaked pattern in the growing season, but exhibited very small fluctuation in the non-growing season. Net ecosystem exchange (NEE) and gross primary production (GPP) were all correlated with some meteorological factors, and they showed a negatively linear correlation with aboveground biomass, while a positive correlation existed between the ecosystem respiration (R_es) and those factors.     

Immunodetection of a 90 000-Mr polypeptide related to yeast plasma membrane ATPase in plasma membrane from maize shoots

Maize shoot plasma membranes were prepared using either polyethyleneglycol (PEG)-dextran phase partition or centrifugation through a 30% sucrose cushion. The ATPase specific activity of membranes obtained with the phase partition method (1.4 μmol P_i · min⁻¹ · mg⁻¹ protein) was twice that of those prepared with the sucrose cushion method. After solubilization by lysolecithin and precipitation by ammonium sulfate, ATPase activities of the order of 3.0–3.5 μmol P_i · min⁻¹ · mg⁻¹ were obtained. A polypeptide of M_r = 90 000 was enriched during ATPase purification.Antibodies against pure plasma membrane ATPase from Saccharomyces cerevisiae inhibited the plant ATPase activity. Immunodetection during purification of the plant enzyme strongly supported the conclusion that the polypeptide of M_r = 90 000 belongs to plant plasma membrane ATPase.     

Oxygen consumption by purified plasmalemma vesicles from wheat roots: Stimulation by NADH and salicylhydroxamic acid (SHAM)

Plasmalemma vesicles from wheat (Triticum aestivum L.) roots consumed O₂ and the addition of 1 mM NADH increased the rate ~ 3-fold (to 15-30 nmol O₂·mg⁻¹·min⁻¹). The NADH-dependent O₂ uptake was abolished by catalase. In the presence of salicylhydroxamic acid (SHAM), an inhibitor of the alternative oxidase pathway in plant mitochondria, NADH-dependent O₂ consumption was stimulated 10–20-fold (to 200–400 nmol·mg^1&#x0304;·min⁻¹). Catalase also abolished this stimulation, which was KCN-sensitive but antimycin A-insensitive, and the production of H₂O₂ during SHAM-stimulated NADH-dependent O₂ uptake was demonstrated. Irrespective of the mechanism, SHAM-stimulated respiration by root plasmalemma makes it difficult to interpret results on root respiration obtained using KCN and SHAM.     

Gas exchange characteristics of Gulf of Mexico coastal marsh macrophytes

Gas exchange characteristics of three major Louisiana Mississippi River deltaic plain marsh species, Spartina patens (Ait.) Muhl., Spartina altemiflora Lois., and Panicum hemitomon Shult., was studied under controlled environment conditions. The optimum temperature for maximum photosynthesis was ≈ 36 °C for S. patens, 27 °C for S. alterniflora, and 28 °C for rP. hemitomon. Net photosynthesis rates at optimum temperature averaged 20.1 μmol · m^t-2 · s^t-1 in S. patens, 22.8 μmol · m⁻² · s⁻¹ in S. alterniflora, and 11.4 μmol · m⁻² · s⁻¹ in P. hemitomon. Photosynthetic light saturation occurred ≈720, 530, and 750 μmol · m⁻² · s⁻¹ in S. patens, S. alterniflora, and P. hemitomon, respectively. Only S. patens had a midday depression of stomatal conductance, but net photosynthesis was not reduced by the depression. Maximum stomatal conductances were 285 mmol · m⁻² · s⁻¹ in S. patens, 238 mmol · m⁻² · s⁻¹ in S. alterniflora, and 335 mmol · m⁻² · s⁻¹ in P. hemitomon. In contract, net photosynthesis values were lower in P. hemitomon compared with the Spartina species, indicating a greater degree of water use efficiency of photosynthesis for both Spartina species.