The Deepwater Horizon blowout in 2010 released an estimated 4.9 million barrels of crude oil into the Gulf of Mexico in the 83 days between the initial explosion and the capping of the well. Response included extensive use of Corexit© oil dispersant. Although South Florida was spared exposure by currents, this event highlights the need for effective bioassay organisms for coral reefs. Amphistegina spp. are benthic foraminifers that host diatom symbionts in a relationship similar to that of coral and their zooxanthellae. Amphistegina spp. occur abundantly in reef communities nearly worldwide, are easily collected and maintained in culture, and are a key component of the FoRAM Index, a indicator of water and sediment quality in coastal waters. The major goals of this project were to develop protocols to test the acute and chronic responses of A. gibbosa to potentially toxic organic chemicals. Initial objectives were to determine lethal concentrations and effects ranges, as defined by the US Environmental Protection Agency, of two components of the Corexit© dispersants. Preliminary experiments indicated that many specimens exposed to propylene glycol (v/v) at concentrations of 2% or higher appeared to be dead following 48-hour exposure, resulting in apparent LC50 of 3% and an initial effects range of 2-4%. When placed in filtered seawater, after 72-hours the observed LC50 was 6%. All parameters assessed, including sub-lethal chronic effects (differences in growth and visible responses after 40 days), revealed an effects range of 0.5% to 12%, above which there was 100% mortality. For 2-butoxyethanol, the apparent LC50 after 48-hour exposure was 0.2%; after 72-hour recovery the LC50 was 1%. In all experiments, a 72-hour recovery period was sufficient to determine acute effects. A key discovery was the observation of inactivity during exposure to toxic substances, followed by recovery when placed in filtered seawater. This observation indicates the potential for dormancy in adult foraminifers exposed to toxic substances that has not previously been reported.

ABSTRACT Benthic foraminifers that host algal symbionts are similar to corals in that they rely on their algal endosymbionts for their energy needs, calcify prolifically, and are sensitive to changes in environmental conditions. They are abundant in the benthos of coastal coral-reef areas and are found throughout the tropical and subtropical regions. Pulse Amplitude Modulated (PAM) chlorophyll fluorometry and chlorophyll a extraction techniques were used to quantify and compare the photosynthetic responses of the benthic foraminiferal, Archaias angulatus and their isolated endosymbionts, Chlamydomonas hedleyi, to short-term changes in temperature. Maximum quantum efficiency (Fv/Fm) and rapid light curves (RLCs), from which relative electron transport rates (rETR) of photosystem II (PSII) were derived, were investigated over a thermal range from 4.4° to 33.9 °C in three experiments that were 7 to 31 days in duration. Typical mean yields (Fv/Fm for healthy holobionts (symbionts in hospite) were 0.6 - 0.7, and for isolated symbionts 0.5 - 0.6. Chronic photoinhibition, indicated by significant decreases in Fv/Fm, occurred at temperatures above 31.0°C; there was minimal reduction in efficiency in cooler treatments. The trends between holobiont and symbionts were very similar in all of the photophysiological parameters measured [yield, photoefficiency (<α>), ETRmax and minimum saturating irradiance (Ek)] and supported the temperature range findings in terms of the tolerance of the specimens in the low temperatures up to 31.0 °C. For all photochemical measurements assessed, the holobiont values tended to be somewhat higher than those for the symbionts, with the exception of Ek, possibly indicating a tight coupling in the host-symbiont response during photosynthesis. Chlorophyll a (<μ>g/foram) was negatively correlated with temperature (r = -0.37, p < 0.001) in Experiments 1 and 2. However, in all 3 experiments, chlorophyll a was variable, suggesting a high degree of individual variability in A. angulatus and the ability to acclimate. Some differences observed among treatments may be related to differences in seasons when the specimens were collected and in length of time in culture prior to experiments. Holobiont median rETR light curve trends and photophysiological derived parameters recorded median Ek ranges of ~100-150 <μ>mol photons m-2 s-1, observed ETRmax light intensities of ~200 <μ>mol photons m-2 s-1 and photoinhibition, induced by increasing irradiance intensities, which occurred > 500 <μ>mol photons m-2 s-1. These light curve trends and derived parameters generally supported previous photosynthesis O2 and CO2 gas production studies of A. angulatus. The differences in responses associated with acclimation should be considered in design of future experimental studies. This was the first known physiological study of the viable temperature range and photobiology of A. angulatus using chlorophyll fluorometry methods. Though commonly found in Caribbean and Atlantic waters ranging from 14.0 - 31.0 °C, these results indicate a wider thermal-tolerance range for A. angulatus than was previously known. Keywords: Foraminifera, Chlamydomonas sp., PAM fluorometry, photosynthesis, algal symbiosis

Foraminiferal data analysis and lithofacies analysis of a three-well transect through the Middle Eocene Yegua Formation in southeast Texas provide insights into the depositional and paleoenvironmental history of the Gulf of Mexico Basin. Vertical and downdip changes in the lithology of the Yegua Formation in the three wells represents the depositional environments of a delta system that prograded onto the continental shelf, updip from the shelf margin. Two progradational episodes and two marine transgressions of the Yegua delta system occurred within this interval of the Yegua Formation in southeast Texas. Factor analysis of benthic foraminiferal census data reveals five major recurring assemblages of benthic foraminifera. These assemblages, or biofacies, occupied environments ranging from marginal marine to normal marine, middle-to-outer shelf environments. The stratigraphic relationships of the five biofacies show paleoenvironmental complexities that are not readily apparent from the lithofacies analysis. Integration of lithologic data and nonforaminiferal paleontologic data with the foraminiferal data produces a detailed paleoenvironmental reconstruction of the Yegua shelf in dip direction. Comparison of the foraminiferal data from the Yegua Formation with modern foraminiferal data from the Gulf of Mexico indicates that several properties of modern foraminiferal assemblages are similar to the foraminiferal assemblages of the Yegua Formation. Generic predominance, species diversity, and planktic to benthic ratios of modem foraminiferal assemblages can be used to help determine the paleoenvironmental significance of the Yegua foraminiferal assemblages. These properties of modern foraminiferal assemblages are not exact analogs for Middle Eocene assemblages and should be applied with caution. / text

A continuous, decadal-scale resolution multi-proxy record of climate variability over the past 1400 years in the northern Gulf of Mexico (GOM) was constructed from a box core recovered in the Pigmy Basin. Proxies include paired analyses of Mg/Ca and oxygen isotopes in the white variety of the planktic foraminifer Globigerinoides ruber and relative abundance variations of G. sacculifer in the foraminifer assemblages. Two multi-decadal intervals of sustained high Mg/Ca values indicate GOM sea-surface temperatures (SSTs) were as warm or warmer than near-modern conditions between 1000 and 1400 yrs BP. Foraminiferal Mg/Ca values during the coolest interval of the Little Ice Age (ca. 250 yrs BP) indicate that SST was 2 - 2.5 degrees Celcius below modern SST. Four minima in the Mg/Ca record between 900 and 250 yrs BP correspond with the Maunder, Spörer, Wolf and Oort sunspot minima, suggesting a link between solar insolation and SST variability in the GOM. An abrupt shift recorded in both the oxygen isotopic ratio of calcite and relative abundance of G. sacculifer occurs ~600 yrs BP. The shift in the Pigmy Basin record corresponds with a shift in the sea-salt-sodium (ssNa) record from the GISP2 ice core, linking changes in high-latitude atmospheric circulation with the subtropical Atlantic Ocean.

Studies of planktic foraminifers have been, and continue to be, very important to paleoceanographic reconstructions and are dependent on the integrity of the carbonate tests. This study investigates the methods and procedures that can be used to obtain an accurate planktic foraminifer assemblage. Samples from Orca Basin boxcore OB-BC4D were processed and examined to obtain census data on planktic foraminifers. Experimentation of the splitting technique demonstrates the method is acceptable for estimating a planktic foraminifer assemblage. The effects of a sonication step in the processing of the faunal assemblage were also examined and revealed that sonication is not recommended for processing planktic foraminifers for faunal-assemblage analyses. Census data revealed downcore variation in the foraminifer species and intervals of increased dissolution over the last 1000 years.

Στην παρούσα εργασία πραγματοποιήθηκαν μικροπαλαιοντολογικές αναλύσεις σε επιλεγμένα δείγματα ιζήματος από πυρήνα που συλλέχθηκε στο Λιβυκό πέλαγος. Σε αυτόν τον πυρήνα έχουν εντοπιστεί ορίζοντες σαπροπηλικής ή παρόμοιας σύστασης καθώς και αποθέσεις λασπούχων ροών. Σκοπός της εργασίας είναι ο προσδιορισμός των παλαιοωκεανογραφικών και παλαιοκλιματικών συνθηκών που αναπτύχθηκαν κατά το χρονικό διάστημα απόθεσης των ιζημάτων που μελετήθηκαν, καθώς και η συσχέτιση τους με αποτελέσματα ερευνών των γειτονικών περιοχών. Η έρευνα πραγματοποιήθηκε από το εργαστήριο Θαλάσσιας Γεωλογίας και Φυσικής Ωκεανογραφίας του Πανεπιστήμιου Πατρών. / --

Η παρούσα εργασία εξυπηρετεί δύο βασικούς σκοπούς. Αφενός τη δημιουργία μιας βάσης δεδομένων που θα επιτρέπει την άντληση συγκεντρωτικών πληροφοριών που αφορούν την κατανομή και διακύμανση των κυριοτέρων πλαγκτονικών τρηματοφόρων καθώς και των τιμών του οξυγόνου δ18Ο στη Μεσόγειο θάλασσα τα τελευταία 18000 χρόνια. Αφετέρου αποσκοπεί στη χωροχρονική επεξεργασία των δεδομένων με αποτέλεσμα την απεικόνιση της απόκρισης της Μεσογείου σε κλιματικές μεταβολές. / The present work serves two basic aims. On one side the creation of a data base that will allow centralized information that concerns the distribution and fluctuation of the mainer plagktonik foraminifera as well as prices of oxygen d18O in Mediterranean Sea the last 18000 years. It also aims in the chorochronikal treatment of data with result the depiction of the reaction of Mediterranean sea in climatic changes.

The central Arctic Ocean is one of the least explored deep sea regions and long biostratigraphic sediment records are sparse. The main focus of this thesis is the Arctic Ocean foraminiferal record and its application to reconstruct paleoceanographic variations and summer sea ice cover changes between late Quaternary interglacial periods. One of the studied cores was retrieved from the central Lomonosov Ridge Intra Basin. This core contains a relatively high-resolution biostratigraphic record spanning Marine Isotope Stages (MIS) 1–3, although with a hiatus encompassing the Last Glacial Maximum. Radiocarbon age calibrations in this core show a decreasing trend of high marine reservoir ages of about 1400 years during the last deglaciation to 700 years in the late Holocene. The cores from the Lomonosov Ridge off Greenland and the Morris Jesup Rise contain preserved calcareous microfossils further back in time than most previously studied central Arctic Ocean cores. The calcium content estimated by X-ray fluorescence scanning of these cores shows a distinct pattern of calcium rich intervals coinciding with peaks in foraminiferal abundance in the sediment record of MIS 1–7. The calcium peaks originate from material accumulated during interglacials, primarily through detrital carbonate and dolomite input from the decaying North American ice sheet and secondarily from biogenic material. Intervals of calcareous benthic foraminifera are found in pre MIS 7 sediments on both the southern Lomonosov Ridge and Morris Jesup Rise. Their assemblage composition and stable carbon isotope data suggest increased primary production and decreased summer sea ice cover compared to the Holocene central Arctic Ocean. This is also suggested for an interval of high abundance of the subpolar planktic foraminifera Turborotalita quinqueloba on the southern Lomonosov Ridge with a proposed MIS 11 age. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Submitted. Paper 3: Submitted.</p>

Release of methane from large marine reservoirs has been linked to climate change, as a causal mechanism and a consequence of temperature changes, during the Holocene to Late Quaternary. These inferred linkages are based primary on variation in benthic foraminifer’s singnatures. This study examines and illustrates deep sea benthic foraminifera from Holocene to Late Quaternary sample from North Pacific Ocean IODP site 890B,Cascadia Margin. Deep sea benthic foraminifera has been quantatively analyzed in samples>125 μm size fractions. Factor and Cluster analysis of the 29 highest ranked species made it possible to identify six biofacies, characterizing distinct deep sea environmental setting. The environmental interpretation of each biofacies is based on the ecology of recent deep sea benthic foraminifera. The benthic faunal record indicates fluctuating deep se condition in environmental parameter including oxygenation, surface productivity and organic food supply. The benthic assemblage show a major shift at 2 to3 kyrs BP and 6 to10.5 BP marked by major turnover in the relative abundance of species coinciding with in increasing amplitude of interstadial cycles. There are strong possibilities of methane flux in this site. Dissociation of gas hydrates and release of methane to the atmosphere could be a cause of increase in the population abundance of highly reducing environmental species, which we interpreted in our data.

In 2005, box cores were collected throughout the Hudson Bay and Strait. A detailed micropaleontological data set has been generated from these cores for this study and is combined with geochemical and geochronological data to observe temporal and spatial oceanographic changes throughout the bay and strait. All of the cores show an increase in tintinnid species and agglutinated foraminifera, and coincident decreases in calcareous foraminifera in younger core sections. In general, these microfossil trends are correlated with higher organic matter content of the younger core sections. This results from a more extensive freshwater plume that causes lowered pH in the superficial sediments and conditions less favourable for the preservation of calcareous tests. Furthermore, with a 14C age constraint in one of the cores, the mid-Holocene depositional and paleoceanographic history is represented, and provides evidence of marine invasion by 7100 cal yrs BP.