OS23B-01
Modulation of shallow water tidal current in a semiarid coastal lagoon
Complex demodulation is becoming quite common in coastal oceanography. Using a bottom-moored ADP, sea surface level and velocity profiles records were obtained during the summer and autumn of 2000 at the inlet of Guaymas Bay, a semiarid coastal lagoon with mixed tidal regime located in the Gulf of California. The velocity vectors were projected along the principal-axis component (94 % of the variance). The residual current Z0 showed an anti-estuary circulation with speed of 5 cm/s. The 144-day velocity time series were used to study the modulation of the shallow water components. Continuous complex tidal demodulation showed that for the vertically-integrated current, the fourth-diurnal band was the most energetic with synodyc modulation. The maxima in amplitude occurred during neap tides, which suggest a contribution of friction via triplet's interaction to generate compound tides. For the depth-dependent current, all bands showed two layers with independent oscillations; the bottom one, up to the 5 m, and the upper one, from the 8 to 12 m. The third-diurnal band was modulated by the declination of the Sun and the Moon; near the summer solstice, there is a clear anomalistic modulation, while near the autumn equinox, the modulation is of the synodyc type. For the fourth-diurnal band, the modulation is mainly synodic type with an anomalistic influence; and in contrast to the vertically-integrated current, the maxima in amplitude occurred during spring tides, which suggests that this field was no sensitive to non-linear friction. In order to study the mechanisms responsible for the annihilation of the shallow water tidal currents in the interface of the two layers, cubic velocity dissipation and internal friction were calculated from the velocity field. It was found that internal friction annihilated the third- and fourth-diurnal bands at the interface. Dissipation appears to have contributed to the current amplitude difference between bottom and surface, and near the autumn equinox to originate non-simultaneous maxima current amplitude between the bottom and upper layer.
OS23B-02
Tidal and inertial currents in the southern Bay of Campeche, southern Gulf of Mexico
Data from March 1 to June 17, 1997 of currents, water temperature, salinity, and sea level in the southern Bay of Campeche were used to describe tidal and inertial currents. Data were low pass filtered using a Lanczos type filter, and transformed to the frequency space with classical Fast Fourier Transform (FFT), and Morlet Wavelets Method (MWM). Results presented the strongest currents in the southwestern part of the bay, with a dominant east-west component. The predominant direction of the current was parallel to the coast, and followed the bathymetry, depicting the strong barotropic effect. The amplitude of tidal current was very small when compared to total amplitudes. The spectral energy was concentrated at the low frequencies bands, correspond to inertial periods, with an approximate duration between two to three days. Some of these oscillations were also observed in the progressive vectors diagrams. The dominance of the spectral energy at low frequencies demonstrated the influence of the mesoscale cyclonic and the small anticyclonic eddies, of the northeastern Bay of Campeche, in southwestern currents.
OS23B-03
Fortnightly Variability At The Transition Between Two Sub-Estuaries
Profiles of current velocity from an Acoustic Doppler Current Profiler (ADCP) and of water salinity, temperature and density from a Conductivity-Temperature-Depth (CTD) recorder, were combined with surface salinity, temperature and density from a Conductivity-Temperature (CT) recorder to elucidate the fortnightly variability at the Lafayette River entrance. The Lafayette River connects at its mouth with the Elizabeth River, which is a tributary to the James River in the Chesapeake Bay. Data were collected in four experiments during consecutive spring and neap tides in the autumn of 2000, and in the spring of 2001. Each experiment was carried out for ~25 hours and consisted of three across-estuary transects: one at the mouth, where the Elizabeth River estuary influences the Lafayette River estuary, and two more toward the head of the estuary. The maximum depth of the transects was <5 m, and despite the shallowness, the mean flow showed two-layer exchange during neap tides. During spring tides there was an evident recirculation where the two sub-estuaries interact and a marked lateral density structure. During neap tides, there was a recirculation consisting of inflow in the northern half of the estuary and net outflow at the surface and net inflow at the bottom in the southern half of the estuary. The recirculation at the mouth is intensified during wet periods due to intense river discharge. The along-estuary dynamics is that proposed by the theory, between pressure gradient and friction.
OS23B-04
Natural and Anthropogenic Influences on Coastal Evolution Rates: St. John, USVI
Sediment cores collected in salt ponds along the coast of St. John, USVI, show that anthropogenic activities have accelerated the rate of coastal evolution. Previous phases of this research indicate that at least some salt ponds form by coral reef growth cutting off open embayments. Over time, ponds fill with island-derived sediments. Rates of sediment accumulation have been shown to increase where anthropogenic activities are present. The objective of this study is to quantify the time required to infill salt ponds in natural and anthropogenically influenced settings. Sediment cores were collected from five salt ponds, chosen primarily on the basis of degree of anthropogenic development within the watershed. Based on detailed geochronological analyses (210Pb, 137Cs, and 7Be for the last 100 years, and 14C for long-term accumulation) we determined accumulation rates using two methods. Linear accumulation rates were calculated to determine sediment accumulation over time. Compacted linear accumulation rates take into consideration compaction of sediments over time. Results show that ponds naturally infill at a rate of 3 - 7 cm/100 yrs. Ponds in pristine watersheds (Newfound Bay) have maintained their natural accumulation rate of 3 - 7 cm/100 yrs. Ponds in areas of low anthropogenic activities (Long Bay/Southgate) infill at 4 - 9 cm/100 yrs, reflecting a slight increase in accumulation due to anthropogenic activity. Ponds moderately impacted by anthropogenic activity (Fish Bay) show a substantial increase of 15 - 20 cm/100 yrs accumulation rate. This compares to heavily impacted areas, such as Coral Bay which has been shown to exhibit a 10-fold increase in sediment accumulation rate over the last 25-50 years. Thus, results show a progressive increase in sediment accumulation rate linked to increasing levels of anthropogenic activities within the associated watershed. Given these rates, ponds naturally become completely infilled in 4,000-6,000 years. Anthropogenic activities cause premature infilling of salt ponds 500-1,000 years sooner than under natural conditions. Once ponds are completely filled, sediments will empty directly into the marine environment, increasing the potential for degradation of nearby marine ecosystems (see companion poster by Larson, et. al).
OS23B-05
Uranium and lanthanides in surficial sediments of Laguna Ojo de Liebre and evaporation ponds of Exportadora de Sal, Guerrero Negro, México.
To assess uranium and lanthanides behavior in hypersaline environments, surficial sediment samples were taken from Laguna Ojo de Liebre as well as from the evaporation ponds of Exportadora de Sal (the largest natural salt producing facility in the continent). A total of 63 surficial sediment samples from the laguna and 30 samples from the ponds were analyzed by inductive coupled plasma-mass spectrometry for uranium (sediments, deposits and solution) and instrumental neutron activation analysis for REEs in sediments and deposits. Results show that the behavior is all but similar between light and heavy REEs with the exception of Eu which shows a very different pattern of surficial distribution in Laguna Ojo de Liebre with a maximum concentrations in the sediments near the head of the lagoon. Data normalized with North American Shale Composite (NASC) show 3 distinct signature patterns on the surficial sediments, all of them enriched regarding the values of NASC. As for U total content in sediments and solid deposits it shows a higher concentration towards the head of the lagoon (3 mg/kg), from where the water is pumped to the sequence of evaporation ponds, with the lowest values being close to 1 mg/kg near the mouth of the lagoon. The interesting phenomenon begins in the evaporation ponds, where uranium is almost constant in sediments and deposits (0.15-1.5 mg/kg) but behaves conservately in the brine solution, increasing proportionally with salt content (U, 5-20 mg/kg; salt content, 40-250 g/kg). Non lithogenic U was calculated with Sc as reference. Most of the measured U was non lithogenic in the sediments of the lagoon and ponds. The distribution coefficient k= U(non-lith)/U(dis) shows a maximum value at ponds I and II (salt content 40-80 g/kg) decreasing with increasing salinity.
OS23B-06
Massive Rock Detachments from the Continental slope of the Balsas River Submarine Delta that occur due to Instability of Sediments which Produce Turbidity Currents and Tsunamis
During the NOAA oceanographic delivery cruise of the US R/V "Roger Revelle" to the Scripps Institution of Oceanography at the University of California in San Diego, California USA, in July 1996; a well calibrated bathymetric equipment, the SeaBeam* 2012, was tested. Good resolutions in data allowed bathymetric mapping to visualize the sea floor relief. Detailed colorful chartographic images showed a portion of the continental slope between the Balsas River Delta and the Middle America Trench and between the Balsas Canyon and La Necesidad Canyon. The surveyed area covered more than 3 000 square kilometers. After the delivery cruise, one of the goals was to measure and analyze the Morphobathymetry of the uneven lower portion of the Balsas River Submarine Delta. So far some of the findings with the morphometric analyses consist of several isolated slump scars that each comprise more than 12 cubic kilometers in volume and a multiple slump scar with an evident steep hollow about 200 cubic kilometers absent of rock. These volumes of rock apparently underwent a remobilization from the slope during the Late Quaternary. The rock detachments occured in relatively small portions but in instantaneous massive displacements because of their instability as well as other identified factors in the region. Over time more and more authors have accepted that coastal cuts or submarine slump scars have been left by sudden movements of rock and fluids. The phenomena that occur in the region in general, are accompanied on one side by potential and kinetic energies like falling bodies, flows and gravity waves, and on the other side, by mass transfer of rock and fluid mobilization like turbidity currents, accumulations, sea wave surges or tsunamis. In some cases the phenomena is produced by another natural triggering forces or by an earthquake. We propose that events like these, i.e. massive detachments and their products such as accumulations, turbidity currents and depositional debrites or even modern turbidites in the troughs of the Middle America Trench and last but not least, tsunamis; have been occurring in the recent past in this portion of the continental margin of the East Pacific Ocean. In relation to this, no records or documentation at all of those features have been carried out in association with their mentioned products. In despite of this, phenomena will continue to occur in the future. In some towns in the low lands and shores, sea wave surges or tsunamis that have impacted along the coasts in southwestern Mexico have been observed, in particular near the Balsas River mouth, in Las Truchas - Lazaro Cardenas, State of Michoacan, where a Siderurgical Industrial Complex is located. However, no report or document on sea level oscillation, has been published in connection to any slump scar, seismic hypocenter or a trigger effect of another nature, v. gr. meteorological factors such as air pressure; hydrographic factors such as body waves; planets in line such as tidal waves; geological factors such as volcanoes; or others. In relation to other situations, new representative depositional models of modern debrites and turbidite sequences can help to understand and explain the content of favorable natural conditions to achieve a good ponderability of porosities and permeabilities in ancient turbidite systems in similar paleoenvironments for hydrocarbons and water reservoirs beneath the earth or submarine surfaces.
OS23B-07
Sedimentary Environments and Processes in the Vicinity of Quicks Hole, Elizabeth Islands, Massachusetts
Continuous-coverage multibeam bathymetric models and sidescan sonar imagery, verified with bottom sampling
and photography, provide 1) detailed basemaps that yield topographic and geological perspectives of the sea
floor, 2) a fundamental framework for research and management activities, and 3) information on sedimentary
environments and processes. Interpretations presented here are based on NOAA hydrographic survey H11076
that covers approximately 23 sq. km around Quicks Hole, a major passage through the Elizabeth Islands chain,
offshore southeastern Massachusetts.
Bouldery gravels overgrown with seaweed and sessile fauna dominate the sea floor in Quicks Hole, along
shorelines, and on isolated bathymetric highs. These deposits, which reflect environments of erosion and
nondeposition, are winnowed lags of till from the exposed Buzzards Bay moraine. The sea floor south of the Hole
in Vineyard Sound is characterized by environments associated with coarse bedload transport and covered with
transverse and barchanoid sand waves. Transverse waves exceed 7 m in amplitude, have slip faces
predominantly oriented to the west and southwest, and have straight, slightly sinuous, or curved crests.
Megaripples, which mimic asymmetry of the transverse waves but not necessarily their orientation, are commonly
present on stoss slopes; current ripples are ubiquitous. These smaller bedforms suggest that transport is active
and that sand waves are propagating under the present hydraulic regime. Net sediment transport is primarily to
the west and southwest as evidenced by comparisons with data from an earlier hydrographic survey, orientation
of barchanoid waves, and asymmetry of transverse waves and of scour marks around boulders and shipwrecks.
The sea floor across the northern part of the study area in Buzzards Bay and away from the opening to Quicks
Hole is more protected from wind- and tidally-driven currents. Environments here are primarily characterized by
processes associated with sorting or reworking. Faint current ripples and biologically induced resuspension
reflect these processes. Crabs, whelk, and shell debris are locally common. The sea floor north of Nashawena
Island and in small patches in the lee of nearby isolated bathymetric highs is characterized by low backscatter, a
flat undulating appearance, and predominant long-term deposition. In these areas clayey silt accumulates in
low-energy environments, and amphipod and polychaete tubes, shrimp burrows, and snail and crab tracks are
common.
http:pubs.usgs.gov/of/2006/1357/
OS23B-08
Terrestrial Sediment Delivery to Coastal and Marine Environments: US Virgin Islands
Understanding terrestrial sediment dynamics in high-relief, tropical island settings, such as St. Thomas and St. John, USVI, has become a critical issue, as sediments are a potential threat to the health of down-slope environments. The primary depositional sinks of terrestrial sediments are 1) coastal buffer zones such as salt ponds, which trap sediments and keep them from being input into the marine environment, and 2) near-shore marine environments (coral reefs, seagrasses, algal flats etc.), many of which are adversely affected by terrestrial sedimentation. Land use change by anthropogenic activities has been shown to alter terrestrial sediment dynamics and greatly increase sediment delivery and accumulation rates in coastal and marine environments. Sediment cores collected in salt ponds and the near-shore marine environment were used to determine the sedimentology (texture and composition) and geochronology (using 14C, and 210Pb) prior to anthropogenic activities to define the "natural signal", or "baseline", as well as recent deviations from the "natural signal", which may be attributed to anthropogenic activities. Salt pond and marine sediments in watersheds without anthropogenic activities exhibit no deviations from the "natural signal" in sedimentology or accumulation rate. Salt pond and marine sediments in watersheds with anthropogenic activities contain a deviation from the "natural signal" manifested as an increase in accumulation rate within the last 100 yrs (most likely within the last 25-50 yrs) ranging from 3 -10 times greater than the "natural" accumulation rate. Sedimentologically, salt ponds reflect no recent change, where as marine sediments do show a recent deviation in sedimentology. This marine deviation is represented by an increase in organic content, a decrease in grain size, and a decrease in carbonate content (marine-derived) compared to the "natural signal". This change reflects an increase in terrestrial (non- carbonate, finer-grained) sediment input to the marine environment. Anthropogenic activities result in major impacts on sediment dynamics and sediment delivery to coastal and marine environments. Increased terrestrial sediment input may cause premature infilling of coastal buffer zones such as salt ponds (see companion poster, Wallace et al). Once buffer zones are completely filled, terrestrial sediments are input directly to the near-shore marine environment, increasing the threat to sensitive environments such as coral reefs and seagrasses.
OS23B-09
Holocene Infilling History of Tampa Bay, Florida
Tampa Bay is a shallow, sediment-starved estuary located along the central Florida Gulf coast. Based upon sedimentologic, biostratigraphic, and geochronologic analyses of 120 sediment cores and 190 surface sediment samples, karst-controlled basins located in the mid to upper estuary were found to contain a continuous sedimentary record documenting the Holocene sea-level rise and infilling history. The basal unit sampled in cores consists of organic-rich and/or carbonate-rich sediments containing freshwater fauna. Interpreted as lake deposits, the surficial sediments of these units were dated at approximately 8-9 ka suggesting that isolated sinkhole lakes occupied the region prior to being flooded by the Holocene sea-level rise. Overlying the lake deposits, dm-scale, organic-rich muds containing brackish water fauna, represent the transition from fresh to marine conditions as sea level flooded the region. The flooding surface itself is generally undefined, but sometimes represented by a mm-scale layer of shell fragments likely representing a lag deposit. Age dates bracketing this layer show that flooding occurred approximately 6-7 ka. Overlying sediments consist of 3-4 m of organic-rich, sandy muds with typical estuarine fauna. Age dates from the base of this unit indicate estuarine conditions became established approximately 5.5-6 ka. The modern expression of karst basins is a series of shallow, bathymetric depressions, likely reflecting the historically slow rate (0.030-0.065 cm/yr) of fine- grained sediment accumulation. These shallow depressions continue to function as fine-grained sediment sinks, but are now rapidly filling as the rate of accumulation has dramatically increased by approximately one order-of-magnitude (0.16-0.32 cm/yr) within the past 100 years, likely due to human activities.
OS23B-10
High Resolution Geophysical Survey of Western Long Island Sound Offshore New York: A Seafloor Morphology Shaped by Glacial Features, Tidal Currents, and Human Activity
Western Long Island Sound, near metropolitan New York, averages 16m in water depth, with elongated
depressions up to 40m deep occurring around its axis. These depressions are currently interpreted as ancient
drainage channels that were cut into lake deposits some 15,500 years ago, when glacial Lake Connecticut
occupied the Long Island Sound estuary and completely drained away. In June 2006, as part of a geoscience
educational project, we surveyed a 17km2 area of Long island Sound just off Stamford, CT, with the R/V HUGH
SHARP, using its high resolution multibeam bathymetric sonar and a chirp seismic profiler that imaged the
Holocene sedimentary strata. Preliminary analysis details fields of sand waves, scour marks, outcropping
moraines, pipelines and other human artifacts. Together, this data suggest that the eastward deepening trough
within the study area exposes a glacial-sculpted surface, and that tidal currents produce long E-W drift in the
shadow of a shallow outcrops (possibly, some moraine block). This interpretation is consistent with that
proposed by Poppe et al. [Geo-Marine Letters, 26, 59-68,2006] for Eastern Long Island Sound based on a similar
high resolution survey, and may characterize most of Long Island Sound. Grain size analysis for 9 gravity cores
collected within the survey area will test the energy of the current regime, and confirm (or not) this interpretation.
http:www.explore-the-sound.org
OS23B-11
Hydrographic conditions in the Veracruz Reef System (Western Gulf of Mexico)
The hydrographic conditions over the Veracruz reef system (Western continental shelf of the Gulf of Mexico) are investigated by means of CTD profiles. These were measured during two periods: The first one was doing, between 28-30 January of 2005 in the Arrecifal system of Anton Lizardo, just before a Norte event occurs, and the second one was doing between 6-8 of February of 2005, in front of the Jamapa River region and the Arrecifal system of Veracruz, just after a moderate Norte event take place. The most remarkable result was the notable difference of temperature and salinity values of ~ 2ºC and ~ 2 psu between the southern region (Arrecifal system of Anton Lizardo) and the middle (Jamapa River region) and northern (Arrecifal system of Veracruz) regions, induced by convective mixing after a moderate Norte event pass. Moreover, the temperature values during this period were 3ºC under the optimal range of temperature (25ºC-29ºC) to allow healthy coral reef growth.
OS23B-12
TIDAL FEATURES IN A CORAL REEF SYSTEM (WESTERN GULF OF MEXICO)
For the first time, eleven mini-CTD loggers were moored in the Veracruz Reef System during October and December months of 2004 to monitor ambiental parameters (pressure, temperature and salinity). In this study are presented the results computed from the temporal time-series of pressure, in order to define tide temporal and spatial behaviour. The predominant harmonics were the diurnal K1 and O1, followed by the semidiurnal M2 and S2. Also the lunar fortnightly constituent showed amplitudes comparable to the M2 harmonic. In general the amplitude of each harmonic remains homogeneous along the study area, thus bathymetric features seems not affect completelly this parameter of the tidal wave, oppositely the phase constituents of the tide showed notable differences along to the zone, this difference must be induced by bathymetric effects.
OS23B-13
Application of color infrared aerial photography to assess macroalgal distribution in an eutrophic estuary, Upper Newport Bay, California
Newport Bay is a large estuary in southern California that is subject to anthropogenic nutrient loading, eutrophication and hypoxia. Traditional ground-based methods of assessing algal extent for monitoring and management are limited in that they cannot provide a synoptic view of algal distribution over comparatively large areas. The goal of this study was to explore the application of color infrared aerial photography as an alternative for analyzing the changes in the abundance of macroalgae. Three surveys combining remote sensing (false-color infrared aerial photography) and traditional (ground-based quadrats) sampling methods to quantify macroalgal mat coverage were carried out in Upper Newport Bay (UNB) between July and October 2005. Airborne photographs (scale 1:6000) collected during daytime low tides, clear skies and appropriate sun angle were orthorectified, georegistered and combined into three mosaic composite images, one for each survey. During each aerial photography survey, macroalgal percent cover was measured on the ground at ~30 locations randomly scattered throughout the intertidal mudflat area; these ground data were used for calibration of classification schemes developed for each of the composite images. Using a cluster-analysis classification method, ground samples from each survey were classified into three or four classes, based on similarity of their optical signatures. Before classification, each digital image was transformed by the Minimum Noise Fraction Rotation method to remove noise and enhance contrast between the classes. For classification, the Spectral Angle Mapper scheme was used. All pixels in the images were attributed to classes and the areal extent of each class was estimated. For each class, the averaged percent cover by different substrates was estimated from ground sample data. The total coverage by different substrates was calculated by multiplying the within-cluster percent coverage by cluster areas. This analysis showed that remote sensing is an accurate, effective tool for assessing estuarine, intertidal macroalgal coverage. The macroalgal coverage in UNB increased from 50% in July to 75% in September to 84% in October, and during this time Ulva spp. replaced Ceramium spp. as the dominant alga.
OS23B-14
Morphological Phytoplankton Groups and Trophic State of Topolobampo-Santa Maria-Ohuira, Sinaloa, México
Topolobampo-Santa Maria-Ohuira Lagoon Complex in the Gulf of California presents intense anthropogenic activities, such as agricultural with the drainage of nutrient enriched waters into the system, which affects on its health and integrity have been not evaluated before. Monthly data of physical-chemical variables and phytoplankton from November 2004 to February 2006 were used to define the actual trophic state of the lagoons by means of a trophic index (TRIX), and its imprint on the Morphological Phytoplankton Groups. From the analysis of data distinctive responses were observed for each lagoon. Trophic state and phytoplankton dynamic apparently were determinate by differences in hydrodynamics in each lagoon. Santa Maria lagoon showed higher trophic index values followed by Ohuira and Topolobampo. The phytoplankton community dominated for nannophytoplankton was regulated by nitrogen along the year in the entire lagoon system. However, the relationship between phytoplankton and physical-chemical variables examined by multivariate analysis indicated that in Santa Maria, nutrients from the runoff of fertilizers at the beginning of the fall/winter agriculture cycle influenced the occurrence of diatoms Harmful Algae Blooms (HABs), while in Ohuira higher water residence times have major regulatory effects on a large number of HABs of cyanobacteria and dinoflagellates and a lower Trophic state. A minor grade of affectation in Topolobampo lagoon is suggested by a dominance of the seasonality, a lower water residence times, and non HABs incidence during the period of this study.
OS23B-15
Distribution of organic-walled dinoflagellate cysts in recent marine sediments from the Gulf of Tehuantepec, South Pacific of Mexico.
A qualitative and quantitative study of recent organic-walled dinoflagellate dinocysts recovered in sediments has been undertaken in the coastal zone of the Gulf of Tehuantepec, Mexico. A sediment core was collected in 2004 with a Reineck-type corer using a plastic tube (7 cm i.d); and it was subsampled at 0.3 cm intervals down to 10 cm depth and then at 1 cm intervals at further depths. The 210Pb and 137Cs-derived sedimentation and mass accumulation rates at the site were found to vary from 0.033 to 0.209 cm yr-1, and from 0.05 to 0.29 g cm-2 yr-1., respectively. The cysts concentrations ranged between 477 and 2300 cysts g-1 and the cysts fluxes between 68 a 494 cysts cm-2 yr-1. Twenty-three cyst taxa were identified: Brigantedinium spp., Polysphaeridium zoharyii, Bitectatodinium spongium, Spiniferites delicatus, Quinquecuspis concreta, Echinidinium transparantum, Operculodinium centrocarpum, Selenopemphix quanta, Type Echinidinium granulatum, Echinidinium aculeatum, Protoperidinium americanum, Echinidinium delicatum, Selenopemphix nephroides, Cyst of Protoperidinum stellatum, Lingulodinium machaerophorum, Islandinium spp., Votadinium spinosum, Polykrikos kofoidii, Pentapharsodinium dalei, Tuberculodinium vancampoe, Spiniferites mirabilis, Votadinium calvum and Nematosphaeropsis labyrinthus. The assemblages included cysts of both phototrophic and heterotrophic species, with variation of their respective abundance reflecting changes in the trophic structure of the upper water mass, especially after 1950, with a decrease from ~30% to 15% of photototrophic species, likely as a response to pollution (including cultural eutrophication) created by the industrial development of the adjacent coastal zone. Brigantedinium spp., Polysphaeridium zoharyii and Bitectatodinium spongium, were the dominant species found in the core and are most likely influenced by the seasonal upwelling that characterize the study area, as indicated by the predominance of planktonic foraminiferal species Globigerina bulloides and Globigerinita glutinata throughout the core. Potentially toxic species such as Polysphaeridium zohary (cyst of Pyrodinium bahamense var. compressum) were also observed all along the sediment core and new analysis are to be performed to further investigate their presence in the zone.
OS23B-16
Zooplankton Structure of the La Paz Bay southern Gulf of California and their Relation with the Hydrography during the summer 2004
Physical and biological data were gathered in Bay of La Paz, Southern Gulf of California, in summer, 2004. These include hydrographical data, ADP currents, backscattering signals, in vivo natural fluorescence, as well as, zooplankton samples. The topography of the 15°C shows a dome in the central part of the bay that becomes deeper towards the periphery suggesting the existence of a cyclonic eddy. The 35 salinity topography shows an uplift of 35 m. The eddy has a north-south diameter of approximately 35 km and cover almost all the bay. The zooplankton samples reveal the existence of 23 groups the most abundant were cladocera, copepods, siphonophores, chaetognaths and larvae of crustaceans. The zooplankton biomass presents higher values in the periphery of the eddy indicating an influence of the cyclonic circulation in their distribution.
OS23B-17
The Contemporary State of Development of Free-living Nematodes of the Northwestern Black Sea
The work was carried out on samples taken during an expedition on the Black Sea Western shelf (Bulgarian, Romanian, Ukrainian) in October, 2003 in the framework of the UNDP-GEF Black Sea, Ecosystem Recovery Project. Nematodes due to specific biological characteristics (high productivity, short life cycles) quickly respond to environmental changes by reducing species diversity, increasing abundance and decreasing biomass. Our studies have confirmed this. For the western Black Sea shelf 67 nematode species of 6 orders have been recorded. Of the 12 groups of meiobenthos encountered on the western Black Sea shelf the frequency of the dominating group of nematodes made up 93.8-100%. Results show that quantitative and qualitative characteristics of nematodes in the study areas on the Black Sea shelf are heterogeneous. This is due to hydrological conditions. The Bulgarian and Romanian zone have great depths (from 15 to 125m), while 15-45m depths prevail on the Ukrainian shelf. Each shelf has specific sediment type. As observed earlier sediment type and depth determine the quantitative and qualitative characteristics of nematodes. For the Bulgarian and Romanian shelves there is a tendency for increasing diversity from shallows to deep water. On the Ukrainian shelf the species composition of nematodes is higher at small depth. Quantitative characteristics of nematodes increase from the Bulgarian to the Ukrainian shelf. The nematode fauna on the Bulgarian shelf has the greatest species similarity with that the Romanian. Under the influence of river runoff the species diversity is low in those areas of close proximity. In more distant areas the diversity increases. Key species communities are formed under the influence of the abiotic environmental factors and interrelations between organisms. The study of these key communities around which other species assemble is interesting. Sabatieria abissalis dominates among all key species on the Bulgarian shelf transects making up 37-50% of density of colonization. Besides Sabatieria abissalis on the Romanian shelf transects (35% of density), Sabatieria pulchra occurs from 12 to 35%. Sabatieria pulchra dominates on the Ukrainian shelf. Literature data have shown that the ecological niches of these close related species diverge spatially. Sabatieria abissalis prefer to inhabit the upper layers of sediment with adequate oxygen, while Sabatieria pulchra inhabits sediment layers with low oxygen content in silt sediments. At deep water stations where the anthropogenic load is less, k-dominance curves for species biomass and abundance (ABC curves) showing stable unpolluted nematode communities. The amount of dominating species increased with Sabatieria abissalis prevailing. The results of this study illustrate the part played by nematodes in the formation of quantitative parameters of meiobenthos in this area. This kind of meiobenthos is the most suitable for practical biological monitoring of the Black Sea. The increase or decrease in nematode species diversity gives evidence of the state of meiobenthos communities.
OS23B-18
Ecological estimation of the possible variants new Ukrainian shipping way between the Danube and the Black Sea
The better way or optimal variant means economic advisability of organization and using the way and the same time minimization of anthropogenic press. The first problem's factor is - all kinds' variants cross the area of the Danube Biosphere Reserve. The next factor is - all kinds of variants need dredging works in the sea shallow water so called bar's zone for marine entrance channel. As for natural factors there are also two. The first one is a long term delta evolution and the second is the process of water discharge redistribution. If the human influence to the first factor is still limited the second factor's influence can be unlimited - it is easy to do by jetty or dams construction. At present there are nine possible variants of the DWW: Variant 1. It is an artificial canal built as an ameliorative at 80-s between the Danube and Sasik liman. It provokes the water discharge redistribution up on 16.6% from the Danube run off (from the total Q=3000 m3/c for 54 km), hydrological regime in Ukrainian delta and ecological conditions will be sharply worsened. This project supposed a giant dredging works. Variant 2. The Project of engineer P.S. Chekhovich (1904). The length of the canal is 10 km. (The problems are: it is an artificial canal, needs the bridge, cross the wetlands area, redistribute water discharge from the Danube). Variant 3. Solomonov branch - Zhebryany bay modern Project by engineer V.P. Zizak (2000), The problems are: it is an artificial canal also, but with locks, needs the bridge, to cross the wetlands area, the water discharge redistribution from the Danube up on 2.27% (from the total Q=3000 m3/c for 54 km). The length of the canal is 9 km. Two last variants have orientation from Solomonov arm to Zhebriany bay. The other variants of DWW linked with Ochakovsky and Starostambulsky arms systems. Ochakosky system is dying off system from geological point of view. There are two arms which can be examined for DWW - Prorva arm and Potapovo arm. Besides, Ochakovska system needs dykes along both of shores but its construction may have strong influence on ecosystem. The second variant in this system is Potapovo DWW. So, all problems with dyke constructions are continuing besides this DWW passes through the one of the Strict Protection UNESCO zone in Biosphere Reserve, so call iadro. For fundamental reconstruction of Ochakovska system it is necessary to redistribute water discharge in the inner delta. It means to construct the dam in Starostambulsky system and redistribute water to Ochakovska system. In this case ecological situation in Starostambulsky system will be catastrophic. Hydrology regime modification influences the animal and plant kingdom. In the Starostambulsy mouth there is also the Strict Protection UNESCO zone in Biosphere Reserve. All kinds of alternative variants of DWW are dangerous for ecological condition of Chilia delta because considerable part of fresh water will be withdrawn from Ukrainian part of delta (upper 20 km) and it will provoke degradation of living condition for water plants and animals in the delta and Biosphere reserve including. The other Projects are directly linked with strong influence on the zones under strict protection (UNESCO) in the Danube Biosphere reserve. So, safest project is Bystryy DWW, because its conditions created by nature itself and don't need additional artificial constructions. Ukrainian DWW in Starostambulsky arm can be the reason of ecological and economic problems for Romanian side (silting of Sulina DWW).
OS23B-19
Atlantic and Indian Oceans Pollution in Africa
Africa is the second largest and most populated continent after Asia. Geographically it is located between the Atlantic and Indian Oceans. Most of the Africa's most populated and industrialized cities are located along the coast of the continent facing the Atlantic and Indian Oceans, example of such cities include Casablanca, Dakar, Accra, Lagos, Luanda and Cape town all facing the Atlantic Ocean and cities like East London, Durban, Maputo, Dar-es-salaam and Mogadishu are all facing the Indian Ocean. As a result of the geographical locations of African Coastal Cities plus increase in their population, industries, sea port operations, petroleum exploration activities, trafficking of toxic wastes and improper waste management culture lead to the incessant increase in the pollution of the two oceans. NATURE OF POLLUTION OF THE ATLANTIC OCEAN i. The petroleum exploration activities going on along the coast of "Gulf of Guinea" region and Angola continuously causes oil spillages in the process of drilling, bunkering and discharging of petroleum products in the Atlantic Ocean. ii. The incessant degreasing of the Sea Ports "Quay Aprons" along the Coastal cities of Lagos, Luanda, Cape Town etc are continuously polluting the Atlantic Ocean with chemicals. iii. Local wastes generated from the houses located in the coastal cities are always finding their ways into the Atlantic Ocean. NATURE OF POLLUTION OF THE INDIAN OCEAN i. Unlike the Atlantic ocean where petroleum is the major pollutant, the Indian Ocean is polluted by Toxic / Radioactive waste suspected to have been coming from the developed nations as reported by the United Nations Environmental Programme after the Tsunami disaster in December 2004 especially along the coast of Somalia. ii. The degreasing of the Quay Aprons at Port Elizabeth, Maputo, Dar-es-Salaam and Mongolism Sea Ports are also another major source polluting the Indian Ocean. PROBLEMS GENERATED AS A RESULT OF THE OCEANS POLLUTION i. Recent report released by the renown non governmental organization on environmental pollution the Netherlands based Climate Justice Programme under the aegis of friends of the Earth indicated that the coastal region of Nigeria along accounts for 16 percent of the world's total flare in view of the above coupled with the increasing oil spillages in the African Gulf of Guinea region resulted in the rapid decline in fish, plankton, shrimps and other sea lives along the Coast of Africa facing the Atlantic Ocean. ii. In the more recent time the revering dwellers living around the Coast of Gulf of Guinea region and Somalia's Coast have been complaining of increasing cases of child respiratory illness, land degradation, well pollution, infertility and premature death. iii. Geological strata of the Atlantic Ocean are adversely destroyed by the seismographic activities going on around the Gulf of Guinea region and Angola in particular. iv. The general means of livelihood of the revering dwellers are often threaten by the pollution. POSITION OF THE GOVERNMENTS OF AFRICA Apart from the governments of the federal republic of Nigeria, South Africa, Ghana, Senegal and Tanzania that have either established institutes of Oceanography or Environmental Protection Agencies, the majority of the African governments have shown no signs of checking the menace. POSITION OF THE NON-GOVERNMENTAL ORGANISATION The Netherlands based Climate Justice and the Nigeria Environmental Rights Action are the only non- governmental organizations out of very many that have shown signs of fighting this incessant increase in ocean pollution in Africa.