SUMMER DECLINE OF ULVA LACTUCA (CHLOROPHYTA) IN A EUTROPHIC EMBAYMENT: INTERACTIVE EFFECTS OF TEMPERATURE AND NITROGEN AVAILABILITY?1

Throughout the summer, abundance of Ulva lactuca L. declined while biomass of Cladophora vagabunda (L.) van den Hoek and Gracilaria tikvahiae McLachlan increased in a New England embayment undergoing eu-trophication (Waquoit Bay, Massachusetts). We investigated the physiological basis for the summer dieback, focusing on temporal variations in photosynthetic performance and tissue nitrogen (N). We also compared photosynthetic and N uptake capabilities of U. lactuca with other abundant species in this eutrophic system. Photosynthetic egiciency and capacity of U. lactuca declined markedly at 25°C, compared with a spring (15°C) peak in photosynthetic performance; P_max was 4.6 ± 0.3 and 1.8 ± 0.6 μmol O₂.m^?2.s^?1 during spring and summer, respectively. Notably, summer p_max of other abundant species of the embayment was 1.5–3 × higher than that measured for U. lactuca. Ulva lactuca showed a signifciant photosynthetic response to dissolved inorganic carbon enrichment during summer, when water-column-dissolved CO₂ levels were 20% of spring values. Although ammonium uptake rates of U. lactuca were extremely high at both subsaturating (15μM) and saturating (75 μM) N concentrations, as predicted by the functional-form hypothesis, tissue N fell to 1% by late summer. We suggest that a carbon imbalance, initiated by rising water temperatures and declining water-column N; thermal stress; and biological factors (competition, grazing) all contribute to the recurrent summer decline of U. lactuca in this shallow, eutrophic embayment. Thus, while the morphology of U. lactuca might be considered a successful strategy for disturbed, or “stressed” (sensu Littler and Littler 1980), habitats, its inability to persist and flourish in this environment emphasizes the complexity of factors at work in natural systems.     

Microscopic observations of recovery in the reef-building scleractinian coral,Montastrea annularis,after bleaching on a Cayman reef

Living tissues of a single massive colony of the reef-building scleractinian coral, M. annularis, were sampled at one month intervals following the observation that areas of marked discoloration (bleaching) had developed by the beginning of the summer of 1988. Histological analysis of replicate plugs of tissue from bleached and unbleached regions of that colony allowed comparison of time-matched samples as well as zone-matched samples over a period of six months. During that interval, the entire colony was restored to a uniform and normal degree of pigmentation. Histology of the bleached zones documents the gradual accumulation of zooxanthellae and the thickening of the gastrodermal epithelium of the coral. Once reconstituted, the previously bleached gastrodermis, repopulated with algal symbionts, is indistinguishable from unbleached tissue in the coral colony.     

Seasonal changes in population structure of the tropical deep‐water kelp Laminaria abyssalis

Tropical kelp populations are rare and anomalous relicts of shallow‐water populations that existed during glacial periods of cooler oceanographic climate. The endemic Brazilian tropical kelp, Laminaria abyssalis Joly and Oliveira Filho, occurred at depths below 40 m. The seasonal variations in biological aspects of L. abyssalis sporophyte populations and local variations in seawater nutrients and temperature were evaluated. A population was sampled four times between the austral spring of 2005 to winter 2006. Seasonal variations in the population structure and in the tissue content of nitrogen (N), carbohydrate and pigments were observed. Higher density (6.3 individuals m^?2), biomass (7.3 kg m^?2) and blade area (13 221 cm²) were observed in summer, while the highest percentage of tissue total N (1.6%), carbohydrates (32.9%) and photosynthetic pigments (chlorophyll a = 1.9% and chlorophyll c = 0.4%) were observed in spring. The highest surface area of fertile tissue in L. abyssalis sporophytes (2.36%) was recorded in winter, indicating winter as the season when more investments are made in reproduction. The highest concentrations of total N (6.3 μM) and phosphate (0.6 μM) in seawater were observed in spring and summer, respectively. Seawater temperatures lower than 20°C, which are characteristic of upwelling waters, occurred every month and were most frequent in spring and summer. We show that L. abyssalis invests more in growth in spring and summer and reaches the greatest thallus size and population density in summer. The lower abundance during winter may be related to the lower frequency of temperatures below 20°C and the local seasonal storms that cause turnover of rhodoliths, the main substrate for L. abyssalis.     

Onset of photosynthesis in spring speeds up monoterpene synthesis and leads to emission bursts

Emissions of biogenic volatile organic compounds (BVOC) by boreal evergreen trees have strong seasonality, with low emission rates during photosynthetically inactive winter and increasing rates towards summer. Yet, the regulation of this seasonality remains unclear. We measured in situ monoterpene emissions from Scots pine shoots during several spring periods and analysed their dynamics in connection with the spring recovery of photosynthesis. We found high emission peaks caused by enhanced monoterpene synthesis consistently during every spring period (monoterpene emission bursts, MEB). The timing of the MEBs varied relatively little between the spring periods. The timing of the MEBs showed good agreement with the photosynthetic spring recovery, which was studied with simultaneous measurements of chlorophyll fluorescence, CO₂ exchange and a simple, temperature history‐based proxy for state of photosynthetic acclimation, S. We conclude that the MEBs were related to the early stages of photosynthetic recovery, when the efficiency of photosynthetic carbon reactions is still low whereas the light harvesting machinery actively absorbs light energy. This suggests that the MEBs may serve a protective functional role for the foliage during this critical transitory state and that these high emission peaks may contribute to atmospheric chemistry in the boreal forest in springtime.     

Seasonal changes in critical enzymes of lipogenesis and triacylglycerol synthesis in the marmot (Marmota flaviventris)

Fatty acid metabolism and triacylglycerol synthesis are critical processes for the survival of hibernating mammals that undergo a prolonged fasting period. Fatty acid synthase, fatty-acid-CoA ligase, diacylglycerol acyltransferase, and monoacylglycerol acyltransferase activities were measured in liver and in white and brown adipose tissue, in order to determine whether enzymes of lipogenesis and triacylglycerol synthesis vary seasonally during hibernation in the yellow-bellied marmot (Marmota flaviventris). Compared with mid-winter hibernation, fatty acid synthase activity was higher in all three tissues during early spring when marmots emerged from hibernation and in mid-summer when they were feeding, consistent with the synthesis of fatty acids from the carbohydrate-rich summer diet. Fatty-acid-CoA ligase and diacylglycerol acyltransferase activities were highest in summer in white adipose tissue when triacylglycerol synthesis would be expected to be high; diacylglycerol acyltransferase activity was also high in brown adipose tissue during spring and summer. In liver, however, diacylglycerol acyltransferase specific activity was highest during hibernation, suggesting that triacylglycerol synthesis may be prominent in liver in winter. Monoacylglycerol acyltransferase activity, which may aid in the retention of essential fatty-acids, was 80-fold higher in liver than in white or brown adipose tissue, but did not vary seasonally. Its dependence on palmitoyl-CoA suggests that a divalent cation might play a role in enzyme activation. The high hepatic diacylglycerol acyltransferase activity during hibernation suggests that the metabolism of very low density lipoprotein may be important in the movement of adipose fatty acids to brown adipose tissue and muscle during the rewarming that occurs periodically during hibernation. These studies suggest that enzymes of lipid metabolism vary seasonally in the marmot, consistent with requirements of this hibernator for triacylglycerol synthesis and metabolism.Abbreviations BAT brown adipose tissue - DGAT diacylglycerol acyltransferase - FAS fatty acid synthase - K _m Michaelis constant - MGAT monoacylglycerol acyltransferase - RQ respiratory quotiant - VLDL very low density lipoprotein - WAT white adipose tissue     

Biological interactions and their role in community structure in the rocky intertidal of Helgoland (German Bight,North Sea)

Over 3 successive seasonal cycles (April 1986 to October 1988), field experiments were established within 3 intertidal levels in the sheltered rocky intertidal of Helgoland (North Sea, German Bight). Competitors for space (Mytilus edulis, macroalgae), herbivores (Littorina spp.) and predators (Carcinus maenas) were either excluded from areas (0.25 m²) covered by undisturbed communities or enclosed at natural densities on areas that were cleared before of animals and plants. All the experimental fields (each 0.25 m²) were covered by cages with 4 mm gauze at the sides and a plexiglas top. The results of the experiments in the upper intertidal (occupied byLittorina spp. andEnteromorpha) showed that a natural density of herbivores could not prevent algal settlement and had only little influence on algal growth. Instead abiotic factors (storms, algae washed ashore) decreased the stock of the green algae. Experiments in the mid intertidal, dominated byMytilus (50% cover),Fucus spp. (20%) and grazingL. littorea (100 ind. m^?2) showed that community structure was directly changed both by grazing periwinkles and by competition for space between mussels and macroalgae. WheneverLittorina was excluded, the canopy ofFucus spp. increased continuously and reached total cover within two years. In addition to the increase ofFucus spp., the rock surface and the mussel shells were overgrown byUlva pseudocurvata, which covered the experimental fields during parts of the summer in the absence of herbivores. As soon as perennial species (fucoids) covered most of the experimental areas, the seasonal growth ofUlva decreased drastically. Presence and growth of macroalgae were also controlled by serious competition for space with mussels. EstablishedMytilus prevented the growth of all perennial and ephemeral algae on the rocks. However, the shells of the mussels provided free space for a new settlement ofFucus andUlva. In the lower intertidal (dominated by total algal cover ofF. serratus, herbivores such asL. littorea andL. mariae, and increasing number of predators such asCarcinus), the feeding activity of herbivores can neither prevent the settlement of the fucoid sporelings nor reduce the growth of macroalgae.F. serratus achieved a total canopy on the rock within one year. Doubled density of herbivores prevented the settlement ofFucus and most of the undercover algae. Predation byCarcinus onLittorina spp. had little influence on the herbivore community patterns. However, the crabs supported the establishment of macroalgae by excluding the mussels from the lower intertidal. In summary, the community organization and maintenance in the mid and lower intertidal is influenced to a high degree by biological interactions. Whereas both the relatively important herbivory byL. littorea and competition for space between mussels and macroalgae dominate in the mid intertidal, predation reaches its highest relative degree of importance for community structure in the lower intertidal.     

Resistance to freshwater exposure in White Sea Littorina spp. I: Anaerobic metabolism and energetics

 Anaerobic metabolism and changes in the osmotic concentration of extravisceral fluid were studied in the White Sea periwinkles (Littorina littorea, Littorina saxatilis and Littorina obtusata) during freshwater exposure. Resistance to hypoosmotic stress increased in the order: L. obtusata < L. saxatilis < L. littorea. Our data suggest that osmotic shock is not a primary reason for mortality of the periwinkles under these conditions. During environmental anaerobiosis, considerable succinate accumulation (up to 10–19 μmol g⁻¹ wet weight), and depletion of phosphagen and ATP pools were found in the studied species. Other metabolic end products (alanopine, strombine, lactate, acetate or propionate) were not detected. Succinate accumulation and net ATP breakdown were the fastest in the least resistant species, L. obtusata, and slowest in the most resistant, L. littorea. Rate of ATP turnover decreased during freshwater exposure in L. littorea and L. saxatilis, but not in L. obtusata. Our data suggest that differential resistance of three studied Littorina spp. to extreme hypoosmotic stress may be related to their different abilities to reduce metabolic rate and ATP turnover during sustained anoxia. Species-specific variations in anaerobic capacity of Littorina spp. are discussed in relation to their vertical distribution, size and ecology. Accepted: 4 October 1999     

Development of the alt Mutant of Pisum sativum L

The alt (albina-terminalis) mutant of Pisum sativum L. germinates normally, produces several nodes, and then above a sharp transition produces 2 to 3 bleached nodes, ceases growth, and eventually dies. Green nodes have normal chlorophyll content, absorption spectra, photosynthetic rates, and ultrastructure. In bleaching tissues, the chloroplasts degenerate rapidly, followed by extensive disruption and loss of the remaining cytoplasm and organelles. Application of tissue extracts of normal genotypes of pea, corn, and bean stimulates apical development of alt. The resulting tissues have essentially normal structure and function. Application of thiamine, thiamine monophosphate, and thiamine pyrophosphate also stimulate normal apical development at concentrations of 1 micromolar and above. Partial characterization of the stimulus from pea seed extracts is consistent with thiamine as the active factor.     

Osmotic concentration in three races of honey bee,Apis mellifera L. under environmental conditions of arid zone

Hemolymph osmolarity has great effect on honey bee health, especially in arid and semi-arid zones. It regulates water and nutrients in stressed tissues. Osmotic concentration in three races (Apis mellifera ligustica, A. m. carnica and A. m. jemenitica) of Apis mellifera was tested in central Saudi Arabia during spring and summer seasons in 2015. Newly emerged bee workers were first marked and later their hemolymph was extracted after intervals of 1, 5, 10, 15, 20 and 25 days. A significant positive correlation between age and osmolarity was found in all three races during spring and summer seasons. The lowest combined osmotic concentration for all three races was found after 1 day interval, while the highest osmotic concentration was recorded after 25 days. Among all races, A. m. ligustica showed significantly high osmotic concentration after 25 days in spring and summer seasons as compared to the other two races. Only A. m. jemenitica showed similar osmotic concentration after 10 and 15 days in both spring and summer seasons compared to other two races. Mean osmotic concentration of all three races was significantly different after 20 and 25 days in spring and summer seasons. Overall mean recorded during summer was significantly higher than the mean of spring season. Combined osmotic concentration in young drones of all races was significantly lower than that of old drones during spring and summer seasons.     

Macoma balthica in Spain, a few decades back in climate history

The marine bivalve Macoma balthica has disappeared from the Spanish part of the Bay of Biscay during the past four decades. Investigating the possible role of climate change in forcing this species up north, we translocated it down south, back into two Spanish estuaries, and followed the thermal acclimatization of the metabolic rate during spring, summer and autumn. Our results reveal that in natural populations the respiratory response to temperature becomes down-regulated during summer and autumn. The respiration rate in the southward translocated populations became down-regulated to a safe level at very high temperatures (31 °C), but remained high at average temperatures instead. These translocated populations showed a gradual reduction of the condition-index, down to the level of starvation at the end of summer. Combined with an increased metabolic rate this indicates that the translocated specimens suffered from elevated maintenance rates. We conclude that short-term but frequent exposure to > 30 °C in the Spanish estuaries, induces elevated maintenance rates in M. balthica, and ultimately starvation. M. balthica indeed disappeared from the northern Spanish coast due to increasing summer maxima during the last decades. We prospect that the southern distribution limit of M. balthica will shift further north, and that the clam will eventually disappear from the entire Bay of Biscay with future increases in summer temperatures.     

Seasonal patterns of metabolism and the heat shock response (HSR) in farmed mussels Mytilus galloprovincialis

Mussels (Mytilus galloprovincialis) are the main bivalves cultured in the Mediterranean Sea and in the Thermaikos gulf North of Greece. Global warming might affect these cultures since increases in the sea temperatures especially during summertime and may cause mass mortalities. Thus projections of the effects of global warming and the knowledge of the mechanisms of thermal limitation and adaptation are considered important in this context. In the present work we studied the seasonal expression of Hsp70 and Hsp90 of aquacultured mussels in nature in an effort to examine whether mussels are seasonally thermally stressed. Moreover we determined the activity of the key glycolytic enzyme PK in order to examine seasonal changes in the metabolic profile. The present data showed a biphasic seasonal pattern in the expression of Hsps in the mantle and PAM of M. galloprovincialis. The expression of inducible Hsp72 and Hsp90 increased between February and mid April, and remained constant or decreased slightly by the end of May. Hsps expression started again in early June leading to a gradual increase by mid July and remained by the end of August. The pattern of the HSR indicates increased protein turnover or protein damage in the tissues of aquacultured M. galloprovincialis between winter and summer seasons. The induction temperature is probably limited, and beyond some upper limits there is no further change in the HSR induction temperatures and the HSR sets in. PK activity in the mantle was significantly higher in winter than in spring. Early May saw a reactivation of PK to higher than spring values. Similar to mantle PK, PK activity in PAM was significantly higher in winter than in spring. A slight reactivation was observed by the end of August.     

Fatty Acid Composition of Lipids in <Emphasis Type="Italic">Picea obovata</Emphasis> Needles in the Spring Vegetation Period

The dynamics of the fatty acid (FA) composition of total lipids in needles of Siberian spruce (Picea obovata L.) during the first half (March–July) of the 2010 vegetation season has been studied. Three maxima of the unsaturated fatty acid (UFA) content with increased levels of α-linolenic acid are revealed in the postwinter (March 10–April 6), spring (April 20–May 18), and summer (June 1–July 20) periods. During postwinter and spring vegetation, the UFA increase is accompanied by an increase in the oleic and linoleic desaturation ratios. The spring peak of the 18:3ω3 content coincides with the spring peak in chlorophylls in the light-harvesting complexes of photosynthetic units and with the onset of the net CO₂ assimilation. The summer peak is characterized by the level of chlorophylls, which is the highest over the entire monitoring period. The possible ways that the FA is involved in the rearrangement of the structural and functional organization of the photosynthetic apparatus of a coniferous plant are discussed.     

Tissue water relations of three chaparral shrub species after wildfire

Summary We compared the tissue water relations among resprouts and seedlings of three chaparral species during the first summer drought after wildfire. Two of the species, Rhus laurina and Ceanothus spinosus recover after fire by a combination of resprouting and seedling establishment (facultative resprouters), whereas a third species, Ceanothus megacarpus recovers by seedling establishment alone (obligate seeder). Our objectives were to document any differences in tissue water characteristics that might arise between resprouts and seedlings and to test the hypothesis that seedlings of obligate seeders develop more drought tolerant characteristics of their tissues than seedlings of facultative resprouters. We found that resprouts had much higher predawn values of water potential, osmotic potential, and turgor potentials than seedlings. Predawn turgor potentials of resprouts were 1.5 MPa through July and August when turgor potentials for seedlings remained near 0 MPa. During summer months, midday water potentials were 2 to 3 MPa higher for resprouts than seedlings and midday conductances of resprouts were two to five fold greater than those of seedlings. Even though resprouts did not experience severe water stress like seedlings, their tissue water characteristics, as determined by pressure-volume curve analyses, were similar by the peak of the drought in August. Further-more, the tissue water characteristics of seedlings from the obligate seeder, C. megacarpus, were similar to those of facultative resprouters — R. laurina, and C. spinosus. We attribute the observed differences in plant water status between resprouts and seedlings to differences in rooting depths and access to soil moisture reserves during summer drought. We conclude that the higher growth rates, photosynthetic performance, and survivorship of postfire resprouts are primarily a result of higher water availability to resprouting tissues during summer months. It appears that the greater seedling survivorship during summer drought observed for the obligate seeder, C. megacarpus, is not associated with more favorable tissue water characteristics.     

A hemiparasite in the forest understorey: photosynthetic performance and carbon balance of Melampyrum pratense

• Melampyrum pratense is an annual root‐hemiparasitic plant growing mostly in forest understorey, an environment with unstable light conditions. While photosynthetic responses of autotrophic plants to variable light conditions are in general well understood, light responses of root hemiparasites have not been investigated.
• We carried out gas exchange measurements (light response and photosynthetic induction curves) to assess the photosynthetic performance of M. pratense in spring and summer. These data and recorded light dynamics data were subsequently used to model carbon balance of the hemiparasite throughout the entire growth season.
• Summer leaves had significantly lower rates of saturated photosynthesis and dark respiration than spring leaves, a pattern expected to reflect the difference between sun‐ and shade‐adapted leaves. However, even the summer leaves of the hemiparasite exhibited a higher rate of light‐saturated photosynthesis than reported in non‐parasitic understorey herbs. This is likely related to its annual life history, rare among other understorey herbs. The carbon balance model considering photosynthetic induction still indicated insufficient autotrophic carbon gain for seed production in the summer months due to limited light availability and substantial carbon loss through dark respiration.
• The results point to potentially high importance of heterotrophic carbon acquisition in M. pratense, which could be of at least comparable importance as in other mixotrophic plants growing in forests – mistletoes and partial mycoheterotrophs. It is remarkable that despite apparent evolutionary pressure towards improved carbon acquisition from the host, M. pratense retains efficient photosynthesis and high transpiration rate, the ecophysiological traits typical of related root hemiparasites in the Orobanchaceae.

     

A comparative study of the effect of pH and inorganic carbon resources on the photosynthesis of three floating macroalgae species of a Mediterranean coastal lagoon

This study examines the effect of pH changes on photosynthetic characteristics and the role of dissolved inorganic carbon (DIC) in determining the dominance of three species of macroalgae Chaetomorpha linum (O.F. Müller) Kützing, Gracilaria verrucosa (Hudson) Papenfuss and Ulva sp. in a Mediterranean coastal lagoon. Fluctuations of pH were measured in the lagoon in summer. Water column CO(2) and HCO(3)(-) concentrations inside the algal mat showed significant diurnal fluctuations, from a morning peak to an afternoon low, decreasing 96 and 40%, respectively. The response of photosynthesis to increased pH was examined in laboratory conditions in spring (May) and summer (July). The photosynthetic rate declined rapidly at pH above 8.5 and below 6.5. G. verrucosa responded differently in spring and summer showing acclimation to higher pH in summer than in spring. In Ulva sp. incubations, we observed optimum photosynthesis between pH 6 and 7.5. The decrease in photosynthetic rate below pH 6 was lower (12.30%) than above pH 8 (81.03%). This difference may be related to the origin of the macroalgae, suggesting acclimation to the original pH of the environment. Results from instantaneous photosynthesis measurements indicate that low DIC-availability limits the photosynthetic capacity of G. verrucosa, C. linum and Ulva sp. in spring and of C. linum at high irradiances in summer. Our results also show that G. verrucosa has a higher efficiency at low CO(2) concentrations than C. linum and Ulva sp. It is suggested that G. verrucosa may be better adapted to maintain higher photosynthetic rates than other macroalgae in conditions of tissue N sufficiency and low water DIC concentrations which are typical of shallow coastal environments in summer.     

Spring patterns of freezing resistance and photosynthesis of two leaf phenotypes of Hedera helix

Subdominant evergreen broad-leaved plants occurring in deciduous forests throughout temperate zones have only a short window of optimum photoassimilation in spring before canopy closure. Yet increasing photosynthetic and metabolic activity occurs concurrently with reductions in freezing resistance, resulting in vulnerability of plant tissues to late spring freezing events. Our goal was to document the temporal patterns of photosynthesis versus freezing resistance during spring in adult and juvenile leaf phenotypes of Hedera helix in Switzerland. Freezing resistances in all leaves were well below long-term minimum temperatures experienced at the study site, with adult leaf phenotypes in the forest canopy being more freezing resistant than juvenile leaves occurring closer to the ground. Reductions in freezing resistance were followed by increases in leaf photosynthetic capacities, which appeared synchronized among leaf phenotypes. Adult canopy leaves maintained a higher freezing resistance but lower photosynthetic capacity than juvenile leaves through the end of winter and into early spring. However, shortly after the cessation of freezing temperatures, adult leaves greatly increased their photosynthetic capacity relative to juvenile leaves, yet maintained freezing resistances sufficient to resist late spring freezing events. These patterns highlight the importance of the tradeoff in H. helix between exposure to potentially damaging cold temperatures in late spring and the need for high photosynthetic carbon gains before full canopy closure.     

Conservation and Structural Divergence of Organellar DNA and Gene Expression in Non-Photosynthetic Plastids During Ontogenetic Differentiation and Phylogenetic Adaptation

Plastids of non-photosynthetic cells or tissues, such as chromoplasts or leukoplasts, which develop during the course of ontogenetic differentiation contain DNA which is identical to chloroplast DNA with respect to size, organization and gene content. Also in ribosome-deficient bleached plastids, produced in leaves by experimental treatments or mutation, chloroplast DNA remains unaltered. The chloroplast DNA of various bleached mutant strains of Euglena has suffered major deletions or rearrangements, but is, however, never totally lost. Also leukoplasts of parasitic higher plants contain DNA. In the organellar DNA of several parasitic plants photosynthetic genes are conserved. In the heterotrophic flagellate Astasia and in the holoparasite Epifagus virginiana (Orobanchaceae) the size of the plastid DNA is greatly reduced by major deletions and most or all photosynthetic genes or genes related to the chloroplastic respiratory chain are lost. The residual plastid genomes have, however, retained genes for RNAs, tRNAs and ribosomal polypeptides and these are transcribed, although plastidic RNA-polymerase genes are lost in Epifagus. These findings demand the existence of a nuclear-encoded RNA-polymerase. The relevance of the conservation of plastid DNA and of plastidic gene expression in non-photosynthetic cells is discussed, remains, however, at present elusive. Open reading frames of unknown function might be of particular significance for non-photosynthetic plastids.     

Morphofunctional characterization of the reproductive system of the gastropods <Emphasis Type="Italic">Littorina brevicula,L. mandshurica</Emphasis>, and <Emphasis Type="Italic">Nucella heyseana</Emphasis> from uncontaminated and contaminated areas of Peter the Great Bay,Sea of Japan

The structure and state of the reproductive system were studied in the periwinkles Littorina brevicula and L. mandshurica from the coastal area of Vladivostok and in the dogwhelk Nucella heyseana from the protected area of Vostok Bay and from contaminated sites in Amursky Bay. These species were investigated for the presence of imposex and intersex (pathological changes caused by endocrine disruption under the influence of toxic substances). The pathological changes revealed in the gonads of Littorina were oocyte resorption and lipofuscin accumulation; an intersex condition was not found. Imposex specimens (with penis formation) were found among Nucella females from Amursky Bay. The relative penis length in females was 25% of the penis length in males. This kind of pathology was not found in Nucella from clean waters of Vostok Bay.     

Bacterial Consortium of Millepora dichotoma Exhibiting Unusual Multifocal Lesion Event in the Gulf of Eilat, Red Sea

Colonies of the hydrocoral Millepora dichotoma along the Gulf of Eilat are exhibiting unusual tissue lesions in the form of white spots. The emergence and rapid establishment of these multifocal tissue lesions was the first of its kind reported in this region. A characterization of this morphological anomaly revealed bleached tissues with a significant presence of bacteria in the tissue lesion area. To ascertain possible differences in microbial biota between the lesion area and non-affected tissues, we characterized the bacterial diversity in the two areas of these hydrocorals. Both culture-independent (molecular) and culture-dependent assays showed a shift in bacterial community structure between the healthy and affected tissues. Several 16S rRNA gene sequences retrieved from the affected tissues matched sequences of bacterial clones belonging to Alphaproteobacteria and Bacteroidetes members previously associated with various diseases in scleractinian corals.