Modelización de la distribución espacial de Bactericera cockerelli Sulc. (Hemiptera: Triozidae) en Solanum tuberosum L. (Solanales: Solanaceae)

La producción de Solanum tuberosum L., Lycopersicum esculentum Mill. y Physalis ixocarpa Brot. (Solanales: Solanaceae) ha sufrido fuertes pérdidas económicas por la presencia de Bactericera cockerelli Sulc. (Hemiptera: Triozidae) al asociarse con las enfermedades punta morada o “zebra chip", además de ser el transmisor de Candidatus Liberibacter solanacearum. Las alternativas de control utilizadas han carecido de eficacia por desconocer la distribución espacial del insecto dentro de la parcela. Conocer dicho comportamiento permitiría focalizar las alternativas de control, haciéndolas más eficaces. Este trabajo tuvo por objetivo modelizar la distribución espacial de los estadíos de huevo, ninfa y adulto de B. cockerelli obtenidos en muestreos por transectos en un cultivo de papa, utilizando herramientas geoestadísticas. Los resultados indican que la distribución espacial de las poblaciones de huevos, ninfas y adultos de B. cockerelli fue de tipo agregada en cada fecha de muestreo. La validación cruzada de los semivariogramas obtenidos corrobora la distribución agregada en las poblaciones de B. cockerelli. Por su parte, los mapas elaborados permiten observar la estructura agregada de las poblaciones del insecto, permitiendo identificar áreas infestadas y áreas libres. Se encontró estabilidad espacio temporal para los tres estadios del insecto.

Geochemistry and mineralogy of Eocene-Oligocene sediments of IODP Hole 302-M0002A

In 2004, Integrated Ocean Drilling Program Expedition 302 (Arctic Coring Expedition, ACEX) to the Lomonosov Ridge drilled the first Central Arctic Ocean sediment record reaching the uppermost Cretaceous (~430 m composite depth). While the Neogene part of the record is characterized by grayish-yellowish siliciclastic material, the Paleogene part is dominated by biosiliceous black shale-type sediments. The lithological transition between Paleogene and Neogene deposits was initially interpreted as a single sedimentological unconformity (hiatus) of ~26 Ma duration, separating Eocene from Miocene strata. More recently, however, continuous sedimentation on Lomonosov Ridge throughout the Cenozoic was proclaimed, questioning the existence of a hiatus. In this context, we studied the elemental and mineralogical sediment composition around the Paleogene-Neogene transition at high resolution to reconstruct variations in the depositional regime (e.g. wave/current activity, detrital provenance, and bottom water redox conditions). Already below the hiatus, mineralogical and geochemical proxies imply drastic changes in sediment provenance and/or weathering intensity in the hinterland, and point to the existence of another, earlier gap in the sediment record. The sediments directly overlying the hiatus (the Zebra interval) are characterized by pronounced and abrupt compositional changes that suggest repeated erosion and re-deposition of material. Regarding redox conditions, euxinic bottom waters prevailed at the Eocene Lomonosov Ridge, and became even more severe directly before the hiatus. With detrital sedimentation rates decreasing, authigenic trace metals were highly enriched in the sediment. This continuous authigenic trace metal enrichment under persistent euxinia implies that the Arctic trace metal pool was renewed continuously by water mass exchange with the world ocean, so the Eocene Arctic Ocean was not fully restricted. Above the hiatus, extreme positive Ce anomalies are clear signs of a periodically well-oxygenated water column, but redox conditions were highly variable during deposition of the Zebra interval. Significant Mn enrichments only occur above the Zebra interval, documenting the Miocene establishment of stable oxic conditions in the Arctic Ocean. In summary, extreme and abrupt changes in geochemistry and mineralogy across the studied sediment section do not suggest continuous sedimentation at the Lomonosov Ridge around the Eocene-Miocene transition, but imply repeated periods of very low sedimentation rates and/or erosion.

Isotope ratios, trace elements and ultrastructure results of Mytilus galloprovincialis shells and experimental site data off Ischia (Italy)

Bivalve shells can provide excellent archives of past environmental change but have not been used to interpret ocean acidification events. We investigated carbon, oxygen and trace element records from different shell layers in the mussels Mytilus galloprovincialis combined with detailed investigations of the shell ultrastructure. Mussels from the harbour of Ischia (Mediterranean, Italy) were transplanted and grown in water with mean pHT 7.3 and mean pHT 8.1 near CO2 vents on the east coast of the island. Most prominently, the shells recorded the shock of transplantation, both in their shell ultrastructure, textural and geochemical record. Shell calcite, precipitated subsequently under acidified seawater responded to the pH gradient by an in part disturbed ultrastructure. Geochemical data from all test sites show a strong metabolic effect that exceeds the influence of the low-pH environment. These field experiments showed that care is needed when interpreting potential ocean acidification signals because various parameters affect shell chemistry and ultrastructure. Besides metabolic processes, seawater pH, factors such as salinity, water temperature, food availability and population density all affect the biogenic carbonate shell archive.

Epibiosis between the sand crab Emerita analoga and the mussel Semimytilus algosus

Coastal zones of the Humboldt Current Upwelling System (HCUS) are composed both of rocky and sandy beaches inhabited by macrozoobenthic communities. These show oscillating changes in the dominance of species; the abundance of the sand crab Emerita analoga is linked to phases of the El Niño Southern Oscillation (ENSO). The biogenic surfaces of these crabs serve as substrate for opportunistic colonizers. This study is the first record of an epibiosis between E. analoga and the rock mussel Semimytilus algosus, detected at a southern Peruvian sandy beach. Mussels fouled a wide size-range of adult E. analoga (7.3%) but they themselves belonged to small-size classes. The largest S. algosus was 17.4 mm in length. Highest permanence of epibionts was found on larger sand crabs (maximum between 24 and 27 mm). Significantly more mussels were found on the ventral surface (39.4%) compared to 10 other surface areas of the sand crab. Possible benefits and disadvantages of the observed epibiosis for both the basibiont and the epibiont are discussed.

Diatom deposits in the ostpreußischen Haffe

Als man nach dem ersten Weltkrieg im verkleinerten Deutschland nach der Möglichkeit von Neulandgewinnung suchte, dachte man auch an eineTrockenlegung der ostpreußischen Haffe. Aus diesem Anlaß wurden umfangreiche Bohrungen ausgeführt, um ein möglichst genaues Bild vom Untergrunde der Haffe zu bekommen. Auf Veranlassung der Preußischen Geologischen Landesanstalt wurde ich mit der Untersuchung der Diatomeen in den Bohrproben beauftragt. Die Arbeit wurde 1934 begonnen und Ende 1937 wurde der letzte Arbeitsbericht abgeliefert. Die beabsichtigte Veröffentlichung ist bisher unterblieben, weil die Druckvorlagen später verloren gegangen sind. Seitdem sind über die Haffuntersuchungen mehrere Teilergebnisse veröffentlicht worden, von denen hier schon wegen der Terminologie die pollenanalytischen Arbeiten von L. HEIN (1941) und HUGO GROSS (1941) erwähnt seien, auf die im Abschnitt Il 2e näher eingegangen wird. Bei der geologischen Auswertung war Zurückhaltung geboten; denn es wäre gewagt, allein aus der Perspektive der Diatomeenforschung endgültige Aussagen machen zu wollen. Darum habe ich mich bemüht, das Material so weit aufzuschließen, daß es Geologen später auch bei veränderter Fragestellung auswerten können. "Die Theorien wechseln, aber die Tatsachen bleiben." Der Initiative des Herrn Prof. Dr. K. GRIPP und der finanziellen Hilfe der Deutschen Forschungsgemeinschaft ist es zu verdanken, daß die vorliegende Arbeit im Druck erscheinen kann. Zusammenfassung 1. Nur in den alluvialen Schichten des Kurischen Haffs wurden Diatomeen gefunden. 2. Die Diatomeenflora des Kurischen Haffs besteht zur Hauptsache aus Süßwasserformen. 3. Salzwasserformen finden sich in allen Schichten verstreut unter der Süßwasserflora. Wenn sie auch nach Zahl der Arten in manchen Proben einen erheblichen Prozentsatz der Flora ausmachen, so ist doch die Zahl der Individuen stets so gering, daß man nirgends von einer Brackwasserflora sprechen kann. 4. Die Süßwasserflora besteht in den unteren Schichten vorwiegend aus Grundformen; und zwar machen die epiphytischen Bewohner flacher Sumpfgewässer einen großen Teil der Flora aus. 5. In einzelnen Bohrungen kommt in den untersten alluvialen Schichten eine Grundflora mit zahlreichen Mastogloien vor. Dies sind die ältesten diatomeenführenden Schichten, entstanden in isolierten Sumpfgewässern. 6. Die übrigen Schichten mit überwiegender Grundflora sind vermutlich Ablagerungen der Ancyluszeit. 7. Die oberen Schichten, in denen die Planktondiatomeen überwiegen, dürften größtenteils der Litorina-Transgressionszeit angehören, jedoch ist der Transgressions-Kontakt nicht klar zu erkennen. 8. Das Ende der Litorinazeit ist noch weniger erkennbar, da eine grundsätzliche Veränderung der Flora nach oben nicht zu beobachten ist. 9. Die ostbaltischen Charakterformen sind in allen Schichten vertreten.

Benthic fauna associated with mussel beds and shrimp swarms within hydrothermal fields on the Mid-Atlantic Ridge

Macrofaunal assemblages with prevalence of Bresiliidae shrimps and Mytilidae mussels are abundant in at hydrothermal vents along the Mid-Atlantic Ridge. Mussels inhabit zones of diffuse seeps of hydrothermal fluids with temperature abnormalities up to several degrees. Shrimps inhabit an extreme biotope in a mixed interface between seawater and hydrothermal fluids at temperature up to 20-30°C. We studied the mussel and shrimp assemblages in three hydrothermal vent fields: Rainbow, Broken Spur, and Snake Pit. Species richness of the mussel assemblages within at least two fields (Broken Spur and Snake Pit) is higher as compared with shrimps from the same hydrothermal vent fields. Fauna inhibiting shrimp swarms lack almost any taxa specific for particular assemblages: almost all the taxa are also present in the mussel beds. Structure of the shrimp assemblage is less homogeneous as compared with that of the mussel assemblage. Population prevalence of one taxon (Copepoda) in the shrimp assemblage is most likely connected with extreme and unstable conditions of the biotope occupied by the shrimps in a hydrothermal field. Taxonomic similarity between the mussel and shrimp assemblages within one hydrothermal vent field is higher as compared with similarity between the mussel (or shrimp) assemblages from different fields.

Stable isotope ratios in shells of marine organisms

Oxygen and carbon isotope analyses have been carried out on calcareous skeletons of important recent groups of organisms. Annual temperature ranges and distinct developmental stages can be reconstructed from single shells with the aid of the micro-sampling technique made possible by modern mass-spectrometers. This is in contrast to the results of earlier studies which used bulk sampIes. The skeletons analysed are from Bermuda, the Philippines, the Persian Gulf and the continental margin off Peru. In these environments, seasonal salinity ranges and thus annual variations in the isotopic composition of the water are small. In addition, environmental parameters are weIl documented in these areas. The recognition of seasonal isotopic variations is dependant on the type of calcification. Shells built up by carbonate deposition at the margin, such as molluscs, are suitable for isotopic studies. Analysis is more difficult where chambers are added at the margin of the shell but where older chambers are simultaneously covered by a thin veneer of carbonate e. g. in rotaliid foraminifera. Organisms such as calcareous algae or echinoderms that thicken existing calcareous parts as weIl as growing in length and breadth are the most difficult to analyse. All organisms analysed show temperature related oxygen-isotope fractionation. The most recent groups fractionate oxygen isotopes in accordance with established d18O temperature relationships (Tab. 18, Fig. 42). These groups are deep-sea foraminifera, planktonic foraminifera, serpulids, brachiopods, bryozoa, almost all molluscs, sea urchins, and fish (otoliths). A second group of organisms including the calcareous algae Padina, Acetabularia, and Penicillus, as weIl as barnacles, cause enrichment of the heavy isotope 18O. Finally, the calcareous algae Amphiroa, Cymopolia and Halimeda, the larger foraminifera, corals, starfish, and holothurians cause enrichment of the lighter isotope 16O. Organisms causing non-equilibrium fractionation also record seasonal temperature variations within their skeletons which are reflected in stable-oxygen-isotope patterns. With the exception of the green algae Halimeda and Penicillus, all organisms analysed show lower d13C values than calculated equilibrium values (Tab. 18, Fig. 42). Especially enriched with the lighter isotope 12C are animals such as hermatypic corals and larger foraminifera which exist in symbiosis with other organisms, but also ahermatypic corals, starfish, and holothurians. With increasing age of the organisms, seven different d13C trends were observed within the skeletons. 1) No d13C variations are observed in deep-sea foraminifera presumably due to relatively stable environmental conditions. 2) Lower d13C values occur in miliolid larger foraminifera and are possibly related to increased growth with increasing age of the foraminifera. 3) Higher values are found in planktonic foraminifera and rotaliid larger foraminifera and can be explained by a slowing down of growth with increasing age. 4) A sudden change to lower d13C values at a distinct shell size occurs in molluscs and is possibly caused by the first reproductive event. 5) A low-high-Iow cycle in calcareous algae is possibly caused by variations in the stage of calcification or growth. 6) A positive correlation between d18O and d13C values is found in some hermatypic corals, all ahermatypic corals, in the septa of Nautilus and in the otoliths of fish. In hermatypic corals from tropical areas, this correlation is the result of the inverse relationship between temperature and light caused by summer cloud cover; in other groups it is inferred to be due to metabolic processes. 7) A negative correlation between d18O and d13C values found in hermatypic corals from the subtropics is explained by the sympathetic relationship between temperature and light in these latitudes. These trends show that the carbon isotope fractionation is controlled by the biology of the respective carbonate producing organisms. Thus, the carbon isotope distribution can provide information on the symbiont-host relationship, on metabolic processes and calcification and growth stages during ontogenesis of calcareous marine organisms.

Porewater concentrations, pH, single cell number, anaerobic oxidation of methane (AOM) rate, sulfate reduction (SR) rate of samples during METEOR cruise M76/3b at the REGAB cold seep site from the West African margin in 2008

The giant pockmark REGAB (West African margin, 3160 m water depth) is an active methane-emitting cold seep ecosystem, where the energy derived from microbially mediated oxidation of methane supports high biomass and diversity of chemosynthetic communities. Bare sediments interspersed with heterogeneous chemosynthetic assemblages of mytilid mussels, vesicomyid clams and siboglinid tubeworms form a complex seep ecosystem. To better understand if benthic bacterial communities reflect the patchy distribution of chemosynthetic fauna, all major chemosynthetic habitats at REGAB were investigated using an interdisciplinary approach combining porewater geochemistry, in situ quantification of fluxes and consumption of methane, as well bacterial community fingerprinting. This study revealed that sediments populated by different fauna assemblages show distinct biogeochemical activities and are associated with distinct sediment bacterial communities. The methane consumption and methane effluxes ranged over one to two orders of magnitude across habitats, and reached highest values at the mussel habitat, which hosted a different bacterial community compared to the other habitats. Clam assemblages had a profound impact on the sediment geochemistry, but less so on the bacterial community structure. Moreover, all clam assemblages at REGAB were restricted to sediments characterized by complete methane consumption in the seafloor, and intermediate biogeochemical activity. Overall, variations in the sediment geochemistry were reflected in the distribution of both fauna and microbial communities; and were mostly determined by methane flux.

Impact of ocean acidification and warming on respiration, heart rate and acid-base status of Mytilus edulis from the North Sea

Anthropogenic climate change confronts marine organisms with rapid trends of concomitant warming and CO2 induced ocean acidification. The survival and distribution of species partly depend on their ability to exploit their physiological plasticity during acclimatization. Therefore, in laboratory studies the effects of simulated future ocean acidification on thermal tolerance, energy metabolism and acid-base regulation capacity of the North Sea population of the blue mussel Mytilus edulis were examined. Following one month of pre-acclimation to 10 °C and control CO2 levels, mussels were exposed for two weeks to control and projected oceanic CO2 levels (390, 750 and 1120 µatm) before being subjected to a stepwise warming protocol between 10 °C and 31 °C (+ 3 °C each night). Oxygen consumption and heart rates, anaerobic metabolite levels and haemolymph acid-base status were determined at each temperature. CO2 exposure left oxygen consumption rate unchanged at acclimation temperature but caused a somewhat stronger increase during acute warming and thus mildly higher Q10-values than seen in controls. Interestingly, the thermally induced limitation of oxygen consumption rate set in earlier in normocapnic than in hypercapnic (1120 µatm CO2) mussels (25.2 °C vs. 28.8 °C), likely due to an onset of metabolic depression in the control group following warming. However, the temperature induced increase in heart rate became limited above 25 °C in both groups indicating an unchanged pejus temperature regardless of CO2 treatment. An upper critical temperature was reached above 28 °C in both treatments indicated by the accumulation of anaerobic metabolites in the mantle tissue, paralleled by a strong increase in haemolymph PCO2 at 31 °C. Ocean acidification caused a decrease in haemolymph pH. The extracellular acidosis remained largely uncompensated despite some bicarbonate accumulation. In all treatments animals developed a progressive warming-induced extracellular acidosis. A stronger pH drop at around 25 °C was followed by stagnating heart rates. However, normocapnic mussels enhanced bicarbonate accumulation at the critical limit, a strategy no longer available to hypercapnic mussels. In conclusion, CO2 has small effects on the response patterns of mussels to warming, leaving thermal thresholds largely unaffected. High resilience of adult North Sea mussels to future ocean acidification indicates that sensitivity to thermal stress is more relevant in shaping the response to future climate change.

Growth increments of the recent brachiopod Magellania venosa mechanically marked in Paso Comau and Comau Fjord, Chile, 2011/2012

Magellania venosa, the largest recent brachiopod, occurs in clusters and banks in population densities of up to 416 ind/m**2 in Comau Fjord, Northern Chilean fjord region. Below 15 m, it co-occurs with the mytilid Aulacomya atra and it dominates the benthic community below 20 m. To determine the question of why M. venosa is a successful competitor, the in situ growth rate of the brachiopod was studied and its overall growth performance compared with that of other brachiopods and mussels. The growth in length was measured between February 2011 and March 2012 after mechanical tagging and calcein staining. Settlement and juvenile growth were determined from recruitment tiles installed in 2009 and from subsequent photocensus. Growth of M. venosa is best described by the general von Bertalanffy growth function, with a maximum shell length (Linf) of 71.53 mm and a Brody growth constant (K) of 0.336/year. The overall growth performance (OGP index = 5.1) is the highest recorded for a rynchonelliform brachiopod and in the range of that for Mytilus chilensis (4.8-5.27), but lower than that of A. atra (5.74). The maximal individual production (PInd) is 0.29 g AFDM/ind/year at 42 mm shell length and annual production ranges from 1.28 to 89.25 g AFDM/year/m**2 (1-57% of that of A. atra in the respective fjords). The high shell growth rate of M. venosa, together with its high overall growth performance may explain the locally high population density of this brachiopod in Comau Fjord. However, the production per biomass of the population (P/B-ratio) is low (0.535) and M. venosa may play only a minor role in the food chain. Settling dynamics indicates that M. venosa is a pioneer species with low juvenile mortality. The coexistence of the brachiopod and bivalve suggests that brachiopod survival is affected by neither the presence of potential brachiopod predators nor that of space competitors (i.e. mytilids).