Geographic distribution of dinoflagellate cysts in surface sediments

Dinoflagellate cysts are useful for reconstructing upper water conditions. For adequate reconstructions detailed information is required about the relationship between modern day environmental conditions and the geographic distribution of cysts in sediments. This Atlas summarises the modern global distribution of 71 organicwalled dinoflagellate cyst species. The synthesis is based on the integration of literature sources together with data of 2405 globally distributed surface sediment samples that have been preparedwith a comparable methodology and taxonomy. The distribution patterns of individual cyst species are being comparedwith environmental factors that are knownto influence dinoflagellate growth, gamete production, encystment, excystment and preservation of their organic-walled cysts: surface water temperature, salinity, nitrate, phosphate, chlorophyll-a concentrations and bottom water oxygen concentrations. Graphs are provided for every species depicting the relationship between seasonal and annual variations of these parameters and the relative abundance of the species. Results have been compared with previously published records; an overview of the ecological significance as well as information about the seasonal production of each individual species is presented. The relationship between the cyst distribution and variation in the aforementioned environmental parameters was analysed by performing a canonical correspondence analysis. All tested variables showed a positive relationship on the 99% confidence level. Sea-surface temperature represents the parameter corresponding to the largest amount of variance within the dataset (40%) followed by nitrate, salinity, phosphate and bottom-water oxygen concentration, which correspond to 34%, 33%, 25% and 24% of the variance, respectively. Characterisations of selected environments as well as a discussion about how these factors could have influenced the final cyst yield in sediments are included.

Ecophysiology of the marine cyanobacterium, Lyngbya majuscula (Oscillatoriaceae) in Moreton Bay, Australia

Large blooms of the marine cyanobacterium Lyngbya majuscula in Moreton Bay, Australia (27 degrees 05'S, 153 degrees 08'E) have been re-occurring for several years. A bloom was studied in Deception Bay (Northern Moreton Bay) in detail over the period January-March 2000. In situ data loggers and field sampling characterised various environmental parameters before and during the L. majuscula bloom. Various ecophysiological experiments were conducted on L. majuscula collected in the field and transported to the laboratory, including short-term (2h) C-14 incorporation rates and long-term (7 days) pulse amplitude modulated (PAM) fluorometry assessments of photosynthetic capacity. The effects of L. majuscula on various seagrasses in the bloom region were also assessed with repeated biomass sampling. The bloom commenced in January 2000 following usual December rainfall events, water temperatures in excess of 24 degrees C and high light conditions. This bloom expanded rapidly from 0 to a maximum extent of 8 km(2) over 55 days with an average biomass of 210 g(dw)(-1) m(-2) in late February, followed by a rapid decline in early April. Seagrass biomass, especially Syringodium isoetifolium, was found to decline in areas of dense L. majuscula accumulation. Dissolved and total nutrient concentrations did not differ significantly (P > 0.05) preceding or during the bloom. However, water samples from creeks discharging into the study region indicated elevated concentrations of total iron (2.7-80.6 mu M) and dissolved organic carbon (2.5-24.7 mg L-1), associated with low pH values (3.8-6.7). C-14 incorporation rates by L. majuscula were significantly (P < 0.05) elevated by additions of iron (5 mu M Fe), an organic chelator, ethylenediaminetetra-acetic acid (5 mu M EDTA) and phosphorus (5 mu M PO4-3). Photosynthetic capacity measured with PAM fluorometry was also stimulated by various nutrient additions, but not significantly (P > 0.05). These results suggest that the L. majuscula bloom may have been stimulated by bioavailable iron, perhaps complexed by dissolved organic carbon. The rapid bloom expansion observed may then have been sustained by additional inputs of nutrients (N and P) and iron through sediment efflux, stimulated by redox changes due to decomposing L. majuscula mats. (c) 2004 Elsevier B.V. All rights reserved.

The implications of simultaneous smoking initiation for inferences about the genetics of smoking behavior from twin data

We examined early social influences across stages of smoking within the context of a twin study using an environmental exposure specific to smoking: whether twins started smoking at the same time (simultaneous smoking initiation: SSI). We expected that SSI would be a good index of shared social influences on smoking initiation. Rates of SSI were indeed significantly higher in MZ twins and in twins who shared peers and classes, as well as in male twins. With the exception of regular smoking in females, we found no significant difference in estimates of genetic and environmental parameters between SSI and non-SSI pairs for any of the smoking measures that we examined (DSM-IV and Fagerstrom HSI measures of nicotine dependence; DSM-IV nicotine withdrawal; heavy smoking; and in males, regular smoking). For regular smoking in females, allowing for additional shared environmental influences associated with SSI only modestly reduced our estimates of additive genetic variance (56% vs. 68%). These results indicate the important social influences that may occur for smoking initiation do not appear to seriously bias estimates of genetic effects on later stages of smoking.

Diel 'tuning' of coral metabolism: physiological responses to light cues

Hermatypic-zooxanthellate corals track the diel patterns of the main environmental parameters temperature, UV and visible light - by acclimation processes that include biochemical responses. The diel course of solar radiation is followed by photosynthesis rates and thereby elicits simultaneous changes in tissue oxygen tension due to the shift in photosynthesis/respiration balance. The recurrent patterns of sunlight are reflected in fluorescence yields, photosynthetic pigment content and activity of the two protective enzymes superoxide dismutase (SOD) and catalase (CAT), enzymes that are among the universal defenses against free radical damage in living tissue. All of these were investigated in three scleractinian corals: Favia favus, Plerogyra sinuosa and Goniopora lobata. The activity of SOD and CAT in the animal host followed the course of solar radiation, increased with the rates of photosynthetic oxygen production and was correlated with a decrease in the maximum quantum yield of photochemistry in Photosystem H (PSII) (Delta F'/F-m'). SOD and CAT activity in the symbiotic algae also exhibited a light intensity correlated pattern, albeit a less pronounced one. The observed rise of the free-radical-scavenger enzymes, with a time scale of minutes to several hours, is an important protective mechanism for the existence and remarkable success of the unique cnidarian-dinoflagellate associations, in which photosynthetic oxygen production takes place within animal cells. This represents a facet of the precarious act of balancing the photosynthetic production of oxygen by the algal symbionts with their destructive action on all living cells, especially those of the animal host.

La geochimica degli isotopi stabili applicata a reperti scheletrici fossili per ricostruzioni paleoambientali (sito archeologico di Arslantepe –Turchia).

Il sito archeologico di Arslantepe (provincia di Malatya, Turchia) rappresenta un caso di studio di potenziale interesse per l’interazione tra i mutamenti climatici e la storia della civiltà. Il sito, occupato quasi ininterrottamente per un periodo di tempo relativamente lungo (6250-2700 BP), ha fornito una grande quantità di reperti ossei, distribuiti lungo una stratigrafia archeologica relativamente dettagliata e supportata da datazioni al radiocarbonio. Tali reperti, indagati con le tecniche della geochimica degli isotopi stabili, possono costituire degli efficaci proxy paleoclimatici. In questo lavoro è stata studiata la composizione isotopica di 507 campioni di resti ossei umani e animali (prevalentemente pecore, capre, buoi). I rapporti isotopici studiati sono relativi a ossigeno (δ18Ocarb, δ18Oph), carbonio (δ13Ccarb, δ13Ccoll) e azoto (δ15N), misurati nella frazione minerale e organica dell’osso; la variabilità nel tempo di questi parametri, principalmente legati alla paleonutrizione, può essere correlata, direttamente o indirettamente, a cambiamenti dei parametri ambientali quali temperatura e umidità atmosferiche. I risultati indicano che la dieta degli animali selvatici e domestici di Arslantepe era quasi esclusivamente a base di piante a ciclo fotosintetico C3, generalmente tipiche di climi umidi o temperati. La presenza di piante C4, più tipiche di condizioni aride, sembrerebbe essere riconoscibile solamente nella dieta del bue (Bos taurus). La dieta umana era esclusivamente terrestre a base di cereali e carne di caprini con una percentuale esigua o del tutto assente di carne di maiale e bue. Dal punto di vista paleoclimatico il principale risultato del lavoro consiste nel riconoscimento della preservazione di un segnale paleoclimatico a lungo termine (δ18OW, composizione isotopica dell’ossigeno dell’acqua ingerita), che identifica un massimo relativo di umidità attorno al 5000 BP e che si correla, per andamento e ampiezza della variazione a record paleoclimatici di sedimenti lacustri collocati in regioni adiacenti all’area di studio. Sulla base del confronto dei tre segnali isotopici sono state inoltre riconosciute due anomalie climatiche siccitose a breve termine, apparentemente riferibili a due episodi di aridità a scala regionale documentati in letteratura.

Black band disease of corals: Ecology and physiology of Phormidium corallyticum

Black band disease of corals consists of a microbial community dominated by the cyanobacteriurn Phormidium corallyticum. The disease primarily affects reef-framework coral species, Active black band disease continually opens up new substrate in reef environments by destroying coral tissue as the disease line advances across the surface of infected colonies. A field study was carried out to determine the abundance and distribution of black band disease on the reef building corals in the Florida Keys. During July of 1992 and 1993, up to 0.72% of coral colonies were infected with black band disease. Analysis of the distribution showed that the disease was clumped. Seasonal patters varied, with some coral colonies infected year round, others exhibiting reinfection from summer 1992 to summer 1993, and some colonies infected for one year only. Statistical analysis of black band disease incidence in relation to various environmental parameters revealed that black band disease was associated with relatively shallow water depths, higher temperatures, elevated nitrite levels, and decreased ortho-phosphate levels. Additional field studies determined recovery of scleractinian coral colonies damaged or killed through the activities of black band disease over a five-year period. These studies determined if the newly exposed substrate was recolonized through scleractinian recruitment, if there was overgrowth of the damaged areas by the formerly diseased colony, or if coral tissue destruction continued after the cessation of black band disease activity. Tissue loss continued on all coral colonies with only one colony exhibiting new tissue growth. The majority of recolonization was by non-reef-framework corals and octocorallians, limited recruitment by framework species was observed. Physiological studies of P. corallyticum were carried out to investigate the photosynthetic capacity of this cyanobacterium, and to determine if this species has the ability to fix dinitrogen. The results of this research demonstrated that P. corallyticum reaches maximum photosynthetic rates at very low light intensities (27.9 μE/m/sec), and that P. corallyticum is able to carry out oxygenic photosynthesis in the presence of sulfide, an ability that is uncommon in prokaryotic organisms. ^

Relative significance of pelagic, benthic and allochthonous organic matter to microbial carbon cycling in a phosphorus-depleted subtropical estuary (Florida Bay)

Heterotrophic bacteria are important decomposers and transformers of primary production and provide an important link between detritus and the aquatic food web. In seagrass ecosystems, much of seagrass primary production is unavailable through direct grazing and must undergo microbial reworking before seagrass production can enter the aquatic food web. The goal of my dissertation research is to understand better the role heterotrophic bacteria play in carbon cycling in seagrass estuaries. My dissertation research focuses on Florida Bay, a seagrass estuary that has experienced recent changes in carbon source availability, which may have altered ecosystem function. My dissertation research investigates the importance of seagrass, algal and/or cyanobacterial, and allochthonous-derived organic matter to heterotrophic bacteria in Florida Bay and helps establish the carbon base of the estuarine food web. ^ A three tiered approach to the study of heterotrophic bacterial carbon cycling and trophic influences in Florida Bay was used: (1) Spatiotemporal observations of environmental parameters (hydrology, nutrients, extracellular enzymes, and microbial abundance, biomass, and production); (2) Microbial grazing experiments under different levels of top-down and bottom-up influence; and (3) Bulk and compound-specific (bacteria-biomarker fatty acid analysis) stable carbon isotope analysis. ^ In Florida Bay, spatiotemporal patterns in microbial extracellular enzyme (also called ectoenzyme) activities indicate that microorganisms hydrolyzed selectively fractions of the estuarine organic matter pool. The microbial community hydrolyzed organic acids, peptides, and phosphate esters and did not use storage and structural carbohydrates. Organic matter use by heterotrophic bacterioplankton in Florida Bay was co-regulated by bottom-up (resource availability) and top-down (grazer mediated) processes. A bacterial carbon budget based on bacterial, epiphytic, and seagrass production indicates that heterotrophic bacterial carbon cycles are supported primarily through epiphytic production with mixing from seagrass production. Stable carbon isotope analysis of bacteria biomarkers and carbon sources in Florida Bay corroborate the results of the bacterial carbon budget. These results support previous studies of aquatic consumers in Florida Bay, indicating that epiphytic/benthic algal and/or cyanobacterial production with mixing from seagrass-derived organic matter is the carbon base of the seagrass estuarine food web. ^

Characterizations of the major coral diseases of the Philippines: Ulcerative white spot disease and novel growth anomalies of Porites

Coral reefs are in decline worldwide and coral disease is a significant contributing factor. However, etiologies of coral diseases are still not well understood. In contrast with the Caribbean, extremely little is known about coral diseases in the Philippines. In 2005, off Southeast Negros Island, Philippines, I investigated relationships between environmental parameters and prevalence of the two most common coral diseases, ulcerative white spot (UWS) and massive Porites growth anomalies (MPGAs). Samples were collected along a disease prevalence gradient 40.5 km long. Principal component analyses showed prevalence of MPGAs was positively correlated with water column nitrogen, organic carbon of surface sediments, and colony density. UWS was positively correlated with water column phosphorus. This is the first quantitative evidence linking anthropogenically-impacted water and sediment to a higher prevalence of these diseases. Histological and cytological alterations were investigated by comparing tissues from two distinct types of MPGA lesions (types 1 and 2) and healthy coral using light and electron microscopy. Skeletal abnormalities and sloughing, swelling, thinning, and loss of tissues in MPGAs resembled tissues exposed to bacterial or fungal toxins. Both lesion types had decreases in symbiotic zooxanthellae, which supply nutrients to corals. Notable alterations included migrations of chromophore cells (amoebocytes) (1) nocturnally to outer epithelia to perform wound-healing, including plugging gaps and secreting melanin in degraded tissues, and (2) diurnally to the interior of the tissue possibly to prevent shading zooxanthellae in order to maximize photosynthate production. Depletion of melanin (active in wound healing) in type 2 lesions suggested type 2 tissues were overtaxed and less stable. MPGAs contained an abundance of endolithic fungi and virus-like particles, which may result from higher nutrient levels and play roles in disease development. Swollen cells and mucus frequently blocked gastrovascular canals (GVCs) in MPGAs. Type 1 lesions appeared to compensate for impeded flow of wastes and nutrients through these canals with proliferation of new GVCs, which were responsible for the observed thickened tissues. In contrast, type 2 tissues were thin and more degraded. Dysplasia and putative neoplasia were also observed in MPGAs which may result from the tissue regeneration capacity being overwhelmed.

Pulsed parabolic equation model of acoustic transmission (PPEMAT)

Underwater sound is very important in the field of oceanography where it is used for remote sensing in much the same way that radar is used in atmospheric studies. One way to mathematically model sound propagation in the ocean is by using the parabolic-equation method, a technique that allows range dependent environmental parameters. More importantly, this method can model sound transmission where the source emits either a pure tone or a short pulse of sound. Based on the parabolic approximation method and using the split-step Fourier algorithm, a computer model for underwater sound propagation was designed and implemented. This computer model differs from previous models in its use of the interactive mode, structured programming, modular design, and state-of-the-art graphics displays. In addition, the model maximizes the efficiency of computer time through synchronization of loosely coupled dual processors and the design of a restart capability. Since the model is designed for adaptability and for users with limited computer skills, it is anticipated that it will have many applications in the scientific community.

Changing Bacterial Growth Efficiencies across a Natural Nutrient Gradient in an Oligotrophic Estuary

Recent studies have characterized coastal estuarine systems as important components of the global carbon cycle. This study investigated carbon cycling through the microbial loop of Florida Bay by use of bacterial growth efficiency calculations. Bacterial production, bacterial respiration, and other environmental parameters were measured at three sites located along a historic phosphorus-limitation gradient in Florida Bay and compared to a relatively nutrient enriched site in Biscayne Bay. A new method for measuring bacterial respiration in oligotrophic waters involving tracing respiration of 13C-glucose was developed. The results of the study indicate that 13C tracer assays may provide a better means of measuring bacterial respiration in low nutrient environments than traditional dissolved oxygen consumption-based methods due to strong correlations between incubation length and δ13C values. Results also suggest that overall bacterial growth efficiency may be lower at the most nutrient limited sites.

Characterizations of the Major Coral Diseases of the Philippines: Ulcerative White Spot Disease and Novel Growth Anomalies of Porites

Coral reefs are in decline worldwide and coral disease is a significant contributing factor. However, etiologies of coral diseases are still not well understood. In contrast with the Caribbean, extremely little is known about coral diseases in the Philippines. In 2005, off Southeast Negros Island, Philippines, I investigated relationships between environmental parameters and prevalence of the two most common coral diseases, ulcerative white spot (UWS) and massive Porites growth anomalies (MPGAs). Samples were collected along a disease prevalence gradient 40.5 km long. Principal component analyses showed prevalence of MPGAs was positively correlated with water column nitrogen, organic carbon of surface sediments, and colony density. UWS was positively correlated with water column phosphorus. This is the first quantitative evidence linking anthropogenically-impacted water and sediment to a higher prevalence of these diseases. Histological and cytological alterations were investigated by comparing tissues from two distinct types of MPGA lesions (types 1 and 2) and healthy coral using light and electron microscopy. Skeletal abnormalities and sloughing, swelling, thinning, and loss of tissues in MPGAs resembled tissues exposed to bacterial or fungal toxins. Both lesion types had decreases in symbiotic zooxanthellae, which supply nutrients to corals. Notable alterations included migrations of chromophore cells (amoebocytes) (1) nocturnally to outer epithelia to perform wound-healing, including plugging gaps and secreting melanin in degraded tissues, and (2) diurnally to the interior of the tissue possibly to prevent shading zooxanthellae in order to maximize photosynthate production. Depletion of melanin (active in wound healing) in type 2 lesions suggested type 2 tissues were overtaxed and less stable. MPGAs contained an abundance of endolithic fungi and virus-like particles, which may result from higher nutrient levels and play roles in disease development. Swollen cells and mucus frequently blocked gastrovascular canals (GVCs) in MPGAs. Type 1 lesions appeared to compensate for impeded flow of wastes and nutrients through these canals with proliferation of new GVCs, which were responsible for the observed thickened tissues. In contrast, type 2 tissues were thin and more degraded. Dysplasia and putative neoplasia were also observed in MPGAs which may result from the tissue regeneration capacity being overwhelmed.

Macroinvertebrate abundance in montane tropical streams of varying land-use, Ecuador

Despite the importance of tropical montane cloud forest streams, studies investigating aquatic communities in these regions are rare and knowledge on the driving factors of community structure is missing. The objectives of this study therefore were to understand how land-use influences habitat structure and macroinvertebrate communities in cloud forest streams of southern Ecuador. We evaluated these relationships in headwater streams with variable land cover, using multivariate statistics to identify relationships between key habitat variables and assemblage structure, and to resolve differences in composition among sites. Results show that shading intensity, substrate type and pH were the environmental parameters most closely related to variation in community composition observed among sites. In addition, macroinvertebrate density and partly diversity was lower in forested sites, possibly because the pH in forested streams lowered to almost 5 during spates. Standard bioindicator metrics were unable to detect the changes in assemblage structure between disturbed and forested streams. In general, our results indicate that tropical montane headwater streams are complex and heterogeneous ecosystems with low invertebrate densities. We also found that some amount of disturbance, i.e. patchy deforestation, can lead at least initially to an increase in macroinvertebrate taxa richness of these streams.

(Table 1) Physical oceanography during Lance cruise LA99/2 in the marginal ice zone of the Barents Sea

Zooplankton was studied on eight stations in the marginal ice zone (MIZ) of the Barents Sea, in May 1999, along two transects across the ice edge. On each station, physical background measurements and zooplankton samples were taken every 6 h over a 24 h period at five discrete depth intervals. Cluster analysis revealed separation of open water stations from all ice stations as well as high similarity level among replicates belonging to particular station. Based on five replicates per station, analysis of variance (ANOVA) confirmed significant differences (P < 0.05) in abundances of the main mesozooplankton taxa among stations. Relations between the zooplankton community and environmental parameters were established using redundancy analysis (CANOCO). In total, 55% of mesozooplankton variability within studied area was explained by eight variables with significant conditional effects: depth stratum, fluorescence, temperature, salinity, bottom depth, latitude, bloom situation, and ice concentration. GLM models supported supposition about clear and negative relationship between concentration of Oithona similis, and overall mesozooplankton diversity The analyses showed a dynamic relationship between mesozooplankton distribution and hydrological conditions on short-term scale. Furthermore, our study demonstrated that variability in the physical environment of dynamic MIZ of the Barents Sea has measurable effect on the Arctic pelagic ecosystem.

Investigations of artificial sediments from two deep-sea in situ recolonization experiments deployed for one year at the central HAUSGARTEN station IV during ARK-XIX/3c

Commercial exploitation and abrupt changes of the natural conditions may have severe impacts on the Arctic deep-sea ecosystem. The present recolonisation experiment mimicked a situation after a catastrophic disturbance (e.g. by turbidites caused by destabilized continental slopes after methane hydrate decomposition) and investigated if the recolonisation of a deep-sea habitat by meiobenthic organisms is fostered by variations innutrition and/or sediment structure. Two "Sediment Tray Free Vehicles" were deployed for one year in summer 2003 at 2500 m water depth in the Arctic deep-sea in the eastern Fram Strait. The recolonisation trays were filled with different artificial and natural sediment types (glass beads, sand, sediment mixture, pure deep-sea sediment) and were enriched with various types of food (algae, yeast, fish). After one year, meiobenthos abundances and various sediment related environmental parameters were investigated. Foraminifera were generally the most successful group: they dominated all treatments and accounted for about 87% of the total meiobenthos. Colonizing meiobenthos specimens were generally smaller compared to those in the surrounding deep-sea sediment, suggesting an active recolonisation by juveniles. Although experimental treatments with fine-grained, algae-enriched sediment showed abundances closest to natural conditions, the results suggest that food availability was the main determining factor for a successful recolonisation by meiobenthos and the structure of recolonised sediments was shown to have a subordinate influence.

Relative abundance of dinoflagellate cysts in surface sediments and dinoflagellate counts from three sediment cores from the Atlantic sector of the Southern Ocean

In this study we investigate the potential of organic-walled dinoflagellate cysts (dinocysts) as tools for quantifying past sea-surface temperatures (SST) in the Southern Ocean. For this purpose, a dinocyst reference dataset has been formed, based on 138 surface sediment samples from different circum-Antarctic environments. The dinocyst assemblages of these samples are composed of phototrophic (gonyaulacoid) and heterotrophic (protoperidinioid) species that provide a broad spectrum of palaeoenvironmental information. The relationship between the environmental parameters in the upper water column and the dinocyst distribution patterns of individual species has been established using the statistical method of Canonical Correspondence Analysis (CCA). Among the variables tested, summer SST appeared to correspond to the maximum variance represented in the dataset. To establish quantitative summer SST reconstructions, a Modern Analogue Technique (MAT) has been performed on data from three Late Quaternary dinocyst records recovered from locations adjacent to prominent oceanic fronts in the Atlantic sector of the Southern Ocean. These dinocyst time series exhibit periodic changes in the dinocyst assemblage during the last two glacial/interglacial-cycles. During glacial conditions the relative abundance of protoperidinioid cysts was highest, whereas interglacial conditions are characterised by generally lower cyst concentrations and increased relative abundance of gonyaulacoid cysts. The MAT palaeotemperature estimates show trends in summer SST changes following the global oxygen isotope signal and a strong correlation with past temperatures of the last 140,000 years based on other proxies. However, by comparing the dinocyst results to quantitative estimates of summer SSTs based on diatoms, radiolarians and foraminifer-derived stable isotope records it can be shown that in several core intervals the dinocyst-based summer SSTs appeared to be extremely high. In these intervals the dinocyst record seems to be highly influenced by selective degradation, leading to unusual temperature ranges and to unrealistic palaeotemperatures. We used the selective degradation index (kt-index) to determine those intervals that have been biased by selective degradation in order to correct the palaeotemperature estimates. We show that after correction the dinocyst based SSTs correspond reasonably well with other palaeotemperature estimates for this region, supporting the great potential of dinoflagellate cysts as a basis for quantitative palaeoenvironmental studies.