Effect of salinity change on cardiac activity in Hiatella arctica and Modiolus modiolus, in the White Sea

A great majority of salinity studies have dealt with intertidal species. Little is known about the way subtidal animals respond to salinity fluctuations. Even less details are available on invertebrates from the White Sea, which salinity is ca. 25. The heart rate of two subtidal Bivalvia—Hiatella arctica and Modiolus modiolus—exposed to different salinities was recorded. Changes in cardiac activity were monitored for 9 days of the animals’ acclimation to salinities of 15, 20, 30 and 35, and for 4 days of reacclimation (return to the initial salinity of 25). The initial response to salinity change was a significant heart rate reduction. On the other hand, cardiac activity in M. modiolus intensified at salinities of 30 and 35. Reacclimation induced different HR responses: from a decrease to a rise, depending on the species and the salinity applied in the experiment. The differences in responses to salinity are discussed with respect to the morphological and ecological characteristics of the species.     

Home Range and Movement Patterns of Toucans: Implications for Seed Dispersal

Toucans (Ramphastidae) are highly frugivorous, widespread throughout the Neotropics, and travel long distances, thus likely providing dispersal for many tropical trees. Despite being large conspicuous members of the canopy and subcanopy bird community, their movement ecology has been little studied. To understand how these frugivores move through a lowland tropical forest, I tracked the movements of Ramphastos tucanus (White‐throated Toucan), Ramphastos vitellinus (Channel‐billed Toucan), and Pteroglossus pluricinctus (Many‐banded Araçari) in Yasuní National Park, Ecuador. The objectives of this study were to use radiotelemetry to estimate toucan home ranges, movement patterns, and potential seed dispersal distances. Using canopy nets, a total of 20 P. pluricinctus and three Ramphastos toucans were captured, radio‐tagged, and tracked over a 4‐yr period from 2001 to 2005. Average home range sizes were 191 and 86 ha for P. pluricinctus and Ramphastos toucans, respectively. The maximum travel distance in a single 30‐min tracking interval was 3665 m for P. pluricinctus and 3027 m for Ramphastos. Estimated dispersal distances of medium‐sized seeds ranged from 269 to 449 m. Large home range size and long‐distance movements indicate that toucans likely disperse seeds over a scale of hundreds of meters. This study is the first to estimate home range size of any toucan species in intact closed‐canopy forests. Abstract in Spanish is available at http://www.blackwell‐synergy.com/loi/btp .     

Temperature-dependent development rates of plaice (Pleuronectes platessa L.) eggs from the Irish Sea

Experimentally derived temperature-dependent development ratesfor planktonic fish eggs are required for developing IndividualBased Models (IBMs) of early life history stages and for estimatingdaily egg production in ichthyoplankton surveys. Developmentrates of Irish Sea plaice eggs were experimentally determinedfor temperatures between 4.5 and 12° C. Differences in developmentrates were apparent when these results were compared with literaturedata for eggs from North Sea parents. On average, plaice eggsfrom the Irish Sea developed more rapidly and hatched up to2 days earlier compared with North Sea eggs incubated at thesame temperature. In terms of parental effects, larger femalestended to produce larger eggs but egg size decreased over successivebatches from the same female within a year. Temperature-dependentegg development rates were influenced by egg size in a non-linearmanner for eggs incubated at 6° C, but egg size had no effectat higher temperatures. Since most plaice eggs sampled fromthe Irish Sea during ichthyoplankton surveys in 1995 and 2000were found in waters cooler than 8° C, such effects maymodify egg development rates in the wild.     

Adaptations to Captivity in the Butterfly Pieris brassicae (L.) and the Implications for Ex situ Conservation

Captive breeding has been suggested as a method of conserving many threatened vertebrates, and is increasingly being proposed as a valuable conservation strategy for invertebrates. Potential genetic problems associated with ex situ conservation are widely recognized, but a further issue has received less attention: the possibility that populations will undergo adaptation to the captive environment, rendering them less well adapted to survival in the wild. We investigated six traits related to dispersal and reproduction in a culture of the large white butterfly Pieris brassicae (L.), that had been captive for c. 100–150 generations, and in recently wild stock reared simultaneously in a common environment. Individuals in the captive culture were heavier, with smaller wings and lower wing aspect ratios. Females from the captive culture laid many more eggs in cage experiments, and had higher ovary mass at the time of peak egg production. These differences are consistent with adaptation to captive conditions. Over time, similar evolutionary changes may affect invertebrates reared in ex situ conservation programmes, decreasing the likelihood that these species can be re-established in the wild. Although the timescale over which most vertebrates are likely to adapt to captivity is longer, and the traits involved will be different, invertebrates like P. brassicae may also provide a model of potential problems in long-term ex situ conservation programmes for both invertebrates and vertebrates. We suggest that measures to reduce or slow adaptation to captivity should be introduced alongside measures to reduce deleterious genetic effects in captive populations.     

Conservation of S-locus for self-incompatibility in Brassica napus (L.) and Brassica oleracea (L.)

 Self-incompatibility (SI) in Brassica is a sporophytic system, genetically determined by alleles at the S-locus, which prevents self-fertilization and encourages outbreeding. This system occurs naturally in diploid Brassica species but is introduced into amphidiploid Brassica species by interspecific breeding, so that in both cases there is a potential for yield increase due to heterosis and the combination of desirable characteristics from both parental lines. Using a polymerase chain reaction (PCR) based analysis specific for the alleles of the SLG (S-locus glycoprotein gene) located on the S-locus, we genetically mapped the S-locus of B. oleracea for SI using a F₂ population from a cross between a rapid-cycling B. oleracea line (CrGC-85) and a cabbage line (86-16-5). The linkage map contained both RFLP (restriction fragment length polymorphism) and RAPD (random amplified polymorphic DNA) markers. Similarly, the S-loci were mapped in B. napus using two different crosses (91-SN-5263×87-DHS-002; 90-DHW-1855-4×87-DHS-002) where the common male parent was self-compatible, while the S-alleles introgressed in the two different SI female parents had not been characterized. The linkage group with the S-locus in B. oleracea showed remarkable homology to the corresponding linkage group in B. napus except that in the latter there was an additional locus present, which might have been introgressed from B. rapa. The S-allele in the rapid-cycling Brassica was identified as the S₂₉ allele, the S-allele of the cabbage was the S ₅ allele. These same alleles were present in our two B. napus SI lines, but there was evidence that it might not be the active or major SI allele that caused self-incompatibility in these two B. napus crosses. Received: 7 June 1996/Accepted: 6 September 1996     

A comparison of the reproductive cycles of Modiolus modiolus (L.), Cerastoderma (=Cardium) edule (L.), and Mytilus edulis L. in Strangford Lough,Northern Ireland

Summary This paper examines the reproductive cycles of three ecologically important marine bivalves-Modiolus modiolus (L.), Cerastoderma edule (L.), and Mytilus edulis L. in Strangford Lough, Northern Ireland over a period of almost five years.Whilst Modiolus does not appear to become sexually mature until it is several years old, Mytilus and Cerastoderma can reproduce in their first and second years of life respectively. In Cerastoderma and Modiolus sexual maturity is preceded by a period of rapid somatic growth.The subtidal Modiolus population remained in a more or less fully ripe condition virtually throughout the period of this investigation suggesting that this particular population lacked any marked cyclical reproductive activity. We interpret this as evidence of slow but almost continuous release of gametes throughout much of the year, a suggestion which is supported by recruitment data. A small intertidal population of Modiolus in Belfast Lough monitored over a period of two years exhibited a much more seasonal cycle. Here spawning occurred mainly during the autumn and winter. These data suggest that localised environmental factors are exceedingly important in controlling the annual reproductive cycle of this species. Cerastoderma from the mid-tidal sand flats ripened rapidly during the spring and spawned over a relatively restricted period in the summer. In Strangford Lough Mytilus occurs predominantly in the low-shore and while it spawns mainly in the spring and summer the annual cycle is considerably more protracted and variable than in Cerastoderma.Variations in the duration of the spawning periods in these bivalves can perhaps be explained in terms of both environmental stability and the immediate physical conditions experienced by these particular populations. The reproductive strategies exhibited by Cerastoderma, Modiolus, and Mytilus in Strangford Lough are considered in relation to population stability and to the different patterns of mortality which characterise these species in their respective local habitats.     

Electrophoretic investigation of systematic relationships in the marine mussels Modiolus modiolus L., Mytilus edulis L., and Mytilus galloprovincialis Lmk. (Mytilidae; Mollusca)

Genetic variation was assayed electrophoretically at 13–16 loci in Modiolus modiolus, Mytilus edulis, and Mytilus galloprovincialis. High genetic distance ( D ) values were observed between Modiolus modiolus and Mytilus edulis (1.516 ± 0.523) and between Modiolus modiolus and Mytilus galloprovincialis (1.564 ± 0.539), whereas the distance between Mytilus edulis and M. galloprovincialis (0.167 ± 0.118) was rather low. The systematic status ot Mytilus edulis and M. galloprovincialis is discussed in relation to these lindings and the genetic distance values are used to estimate divergence times which in turn are compared with paleontological estimates. The observations of high average heterozygosity in Modiolus modiolus, and high correlations of locus heterozygosity between taxa are discussed briefly.     

Distribution of Nephrops norvegicus (L.) larvae in the western Irish Sea: an example of advective control on recruitment

Results of a survey of Nephrops norvegicus larvae conductedin the western Irish Sea during May 1984 are discussed. Thelarval distributions show a pronounced tongue of high numbersextending southward from the muddy area where they are hatched.The inferred density-driven circulation at the time of the surveyis consistent with the southward transport of larvae. BecauseN.norvegicus requires a muddy substrate for successful larvalsettlement, the processes which influence the circulation mayprovide an important control on the level of recruitment.     

Gape morphology of cod Gadus morhua L., haddock Melanogrammus aeglefinus (L.) and whiting Merlangius merlangus (L.) through metamorphosis from larvae to juveniles in the western Irish Sea

Variations in standard length ( L _S), gape size ( S _G) and jaw length ( L _J) were studied in larval and juvenile gadoids (cod Gadus morhua , haddock Melanogrammus aeglefinus and whiting Merlangius merlangus ) from 4 to 70 mm. The increase in S _G and L _J was not linear with respect to L _S. The relationship was best described by segmented regression lines in all three species, with an inflection point at c . 10·5 mm. The S _G and L _J increased more rapidly in relation to larval L _S for individuals smaller than this inflection point size. The rates of increase slowed significantly post-inflection, an effect more noticeable in S _G data compared to L _J data. In each case, the inflection point fell in the intermediate period of development between the larval and juvenile stages, which could be considered as metamorphosis. Published equations that have been used to predict S _G from L _J lead to the overestimation of gape. New relationships are presented, which may be used to predict S _G from measurements of either L _S or upper jaw length in cod, haddock and whiting.     

Phylogenetic and morphological characterization of the green alga infesting the horse mussel Modiolus modiolus from Vityaz Bay (Peter the Great Bay, Sea of Japan)

In this work, the ultrastructural features and taxonomic position of the green microalga infesting the horse mussel Modiolus modiolus from the north-western Pacific (Vityaz Bay, Peter the Great Bay, Sea of Japan) are reported. Mussels were collected monthly from May to September of 2009. In different months, the prevalence of mussels with green tissues was 16.6-62.5% (mean 43%). The most affected organs were the mantle, digestive gland and gonad. Histological analysis revealed severe infiltration of the connective tissue by hemocytes containing the alga cells. Electron microscopy showed that the alga was morphologically similar to the green algae from the genus Coccomyxa (Chlorophyta: Chlorococcales). Two new primers were designed to generate partial small subunit (SSU) rRNA sequences of the green alga from M. modiolus. Phylogenetic analysis based on the comparison of the SSU rRNA sequences of the trebouxiophyceans confirmed an affiliation of the green alga with the genus Coccomyxa. The sequence (1296 bases) of the green alga from M. modiolus was most closely related to the sequence CPCC 508 (AM981206) (identity 100%), obtained from an acid-tolerant, free-living chlorophyte microalga Coccomyxa sp. and to the sequences EU127470 (identity 99.3%) and EU127471 (identity 99.7%) of the green alga, presumably the true Coccomyxa parasitica, infecting the blue mussel Mytilus edulis from the Flensburg Fjord (North Atlantic).     

Patterns of Deep-Sea Genetic Connectivity in the New Zealand Region: Implications for Management of Benthic Ecosystems

Patterns of genetic connectivity are increasingly considered in the design of marine protected areas (MPAs) in both shallow and deep water. In the New Zealand Exclusive Economic Zone (EEZ), deep-sea communities at upper bathyal depths (<2000 m) are vulnerable to anthropogenic disturbance from fishing and potential mining operations. Currently, patterns of genetic connectivity among deep-sea populations throughout New Zealand’s EEZ are not well understood. Using the mitochondrial Cytochrome Oxidase I and 16S rRNA genes as genetic markers, this study aimed to elucidate patterns of genetic connectivity among populations of two common benthic invertebrates with contrasting life history strategies. Populations of the squat lobster Munida gracilis and the polychaete Hyalinoecia longibranchiata were sampled from continental slope, seamount, and offshore rise habitats on the Chatham Rise, Hikurangi Margin, and Challenger Plateau. For the polychaete, significant population structure was detected among distinct populations on the Chatham Rise, the Hikurangi Margin, and the Challenger Plateau. Significant genetic differences existed between slope and seamount populations on the Hikurangi Margin, as did evidence of population differentiation between the northeast and southwest parts of the Chatham Rise. In contrast, no significant population structure was detected across the study area for the squat lobster. Patterns of genetic connectivity in Hyalinoecia longibranchiata are likely influenced by a number of factors including current regimes that operate on varying spatial and temporal scales to produce potential barriers to dispersal. The striking difference in population structure between species can be attributed to differences in life history strategies. The results of this study are discussed in the context of existing conservation areas that are intended to manage anthropogenic threats to deep-sea benthic communities in the New Zealand region.     

Dispersal patterns in a medium‐density Irish badger population: Implications for understanding the dynamics of tuberculosis transmission

European badgers (Meles meles) are group‐living mustelids implicated in the spread of bovine tuberculosis (TB) to cattle and act as a wildlife reservoir for the disease. In badgers, only a minority of individuals disperse from their natal social group. However, dispersal may be extremely important for the spread of TB, as dispersers could act as hubs for disease transmission. We monitored a population of 139 wild badgers over 7 years in a medium‐density population (1.8 individuals/km²). GPS tracking collars were applied to 80 different individuals. Of these, we identified 25 dispersers, 14 of which were wearing collars as they dispersed. This allowed us to record the process of dispersal in much greater detail than ever before. We show that dispersal is an extremely complex process, and measurements of straight‐line distance between old and new social groups can severely underestimate how far dispersers travel. Assumptions of straight‐line travel can also underestimate direct and indirect interactions and the potential for disease transmission. For example, one female disperser which eventually settled 1.5 km from her natal territory traveled 308 km and passed through 22 different territories during dispersal. Knowledge of badgers' ranging behavior during dispersal is crucial to understanding the dynamics of TB transmission, and for designing appropriate interventions, such as vaccination.     

Primate and Dung Beetle Communities in Secondary Growth Rain Forests: Implications for Conservation of Seed Dispersal Systems

Conservation efforts are often aimed at one or a few species. However, habitat sustainability relies on ecological interactions among species, such as seed dispersal. Thus, a community-scale conservation strategy may be more valuable in some settings. We describe communities of primary (primates) and secondary (dung beetles) seed dispersers from 5 sites in the Brazilian Amazon. We estimate community biomass of these taxa and, using multivariate ordination, examine the potential for natural reforestation at each site, given the communities of seed dispersers present. Since disturbed habitat is increasingly common and increasingly the focus of conservation efforts, we also examine differences among seed disperser communities between primary forest and secondary growth at each site. Analyses of faunal biomass in different localities and habitats indicate that secondary growth receives nearly as much use by primates as primary forest; given the dominant groups of dung beetles in secondary growth, disturbed habitat should show a pattern of seed burial that is clumped and deep. Areas with high biomass of Alouatta spp. and the large nocturnal dung beetle species may have the greatest potential for natural reforestation of secondary growth particularly for large seeded species. The data suggest that knowledge of the biomass of primary and secondary dispersing fauna facilitates predictions for the likelihood of disturbed habitat to regenerate and comparisons of sites in broader geographical areas e.g., Neotropical vs. Paleotropical forests.     

Low-Temperature Stress: Implications for Chickpea (Cicer arietinum L.) Improvement

Chickpea is the third major cool season grain legume crop in the world after dry bean and field pea. Chilling and freezing range temperatures in many of its production regions adversely affect chickpea production. This review provides a comprehensive account of the current information regarding the tolerance of chickpea to freezing and chilling range temperatures. The effect of freezing and chilling at the major phenological stages of chickpea growth are discussed, and its ability for acclimation and winter hardiness is reviewed. Response mechanisms to chilling and freezing are considered at the molecular, cellular, whole plant, and canopy levels. The genetics of tolerance to freezing in chickpea are outlined. Sources of resistance to both freezing and chilling from within the cultivated and wild Cicer genepools are compared and novel breeding technologies for the improvement of tolerance in chickpea are suggested. We also suggest future research be directed toward understanding the mechanisms involved in cold tolerance of chickpea at the physiological, biochemical, and molecular level. Further screening of both the cultivated and wild Cicer species is required in order to identify superior sources of tolerance, especially to chilling at the reproductive stages.     

A comparison of relative growth in Cerastoderma (=Cardium) edule, Modiolus modiolus, and Mytilus edulis (Mollusca: Bivalvia)

Relative growth has been studied in intertidal populations of Cerastoderma edule and Mytilus edulis and in a subtidal population of Modiolus modiolus. Size dimensions were generally more variable and shell thickness generally greater in the intertidal species. Total weight was correlated with shell weight in all three species but there was a progressively greater emphasis on tissue growth through the sequence Cerastoderma, Mytilus, Modiolus. These results are interpreted in terms of differences in stability between their respective habitats.
Analyses of individual year classes in Cerastoderma showed a marked pattern of alternating years of good and poor growth.     

Seasonal temperature compensation in the horse mussel, Modiolus modiolus: metabolic enzymes, oxidative stress and heat shock proteins

Seasonal collections of the subtidal horse mussel, Modiolus modiolus, from a depth of 10 m were made at the Isles of Shoals, New Hampshire to assess changes in overall energetic demand, measured as respiration, the maximal activities of rate-limiting enzymes of intermediate metabolism, level of oxidative stress, and the expression of heat shock proteins (HSP). Weighted respiration rates of mussels from winter collections were significantly lower than summer rates but decreased by less than 20%. Specific activities of several rate-limiting enzymes were measured in mussels from the summer and winter collections at the temperature of collection and the reciprocal seasonal temperature (15 and 5 degrees C). Comparisons of these enzyme activities and the protein concentrations of hexokinase and citrate synthase show that a quantitative strategy is used to acclimatize to winter temperatures by these rate-limiting enzymes of intermediate metabolism. The activities and protein concentrations of the antioxidant enzyme, Cu/Zn superoxide dismutase (SOD) is seasonally indistinguishable while the concentration of HSP 70 was greater in winter than in summer samples. These results show that mussels seasonally compensate for decreases in temperature by increasing the concentration of rate-limiting metabolic enzymes while maintaining the same level of antioxidant protection in summer and winter consistent with high aerobic metabolism in both winter and summer. Lastly, the significantly greater concentrations of HSP70 in winter samples suggests that protein chaperone functions must be maintained while other seasonal adjustments to cold temperatures are occurring.     

Dispersal of Two Species of Trichoptera from Desert Springs: Conservation Implications for Isolated vs Connected Populations

During the Pleistocene, when the climate was wetter and cooler, aquatic habitats in the Great Basin of western North America were much more extensive and connected. As the climate warmed over the last 10000 years, many of these habitats dried but others remained as isolated springs and inland lakes. The isolation of desert springs and lack of dispersal between populations of non-vagile species (e.g. fish, spring snails) has led to genetic differentiation and speciation. However, the extent to which vagile species of aquatic insects disperse from spring to spring is unknown. We examined the population genetics of two caddisflies, Hesperophylax designatus (Limnephilidae) and Lepidostoma ojanum (Lepidostomatidae) that occur in isolated springs in Nevada and eastern California to determine the extent of their dispersal from spring to spring. Mitochondrial DNA sequences indicate that the populations of L. ojanum are isolated and that the populations represent management units. In contrast, H. designatus individuals are flying from spring to spring and their populations are connected by dispersal. Disturbance impacts (e.g. grazing by ungulates, water extraction) that eliminate poor dispersers (e.g. L. ojanum) locally may result in permanent losses of genetic diversity; this is less likely with broader dispersers such as H. designatus.     

Seaweed-Based Biogenic ZnO Nanoparticles for Improving Agro-morphological Characteristics of Rice (Oryza sativa L.)

Journal of Plant Growth Regulation - To develop sustainable nano-agriculture, biogenic ZnO nanoparticles have been prepared using brown seaweed Turbinaria ornata (T. ornata) extract as a priming...     

Buried Alive: The Behavioural Response of the Mussels,Modiolus modiolus and Mytilus edulis to Sudden Burial by Sediment

Sedimentation in the sea occurs through natural processes, such as wave and tidal action, which can be exacerbated during storms and floods. Changes in terrestrial land use, marine aggregate extraction, dredging, drilling and mining are known to result in substantial sediment deposition. Research suggests that deposition will also occur due to the modern development of marine renewable energy. The response to individual burial under three depths of sediment, three sediment fractions and five burial durations was investigated in two mussel species, Modiolus modiolus and Mytilus edulis in specialist mesocosms. Both mussel species showed substantial mortality, which increased with duration of burial and burial by finer sediment fractions. M. modiolus was better able to survive short periods of burial than M. edulis, but at longer durations mortality was more pronounced. No mortality was observed in M. modiolus in burial durations of eight days or less but by 16 days of burial, over 50% cumulative mortality occurred. Under variable temperature regimes, M. edulis mortality increased from 20% at 8°C to over 60% at 14.5 and 20°C. Only M. edulis was able to emerge from burial, facilitated by increased byssus production, laid mostly on vertical surfaces but also on sediment particles. Emergence was higher from coarse sediment and shallow burials. Byssus production in M. edulis was not related to the condition index of the mussels. Results suggest that even marginal burial would result in mortality and be more pronounced in warm summer periods. Our results suggest that in the event of burial, adult M. modiolus would not be able to emerge from burial unless local hydrodynamics assist, whereas a small proportion of M. edulis may regain contact with the sediment water interface. The physiological stress resulting in mortality, contribution of local hydrodynamics to survival and other ecological pressures such as mussels existing in aggregations, are discussed.