water level fluctuations emersion regimes and variations of echinoid populations on a caribbean reef flat abstract this paper examines fluctuations in water level over a caribbean reef flat at punta galeta panama in an analysis of approximately ten years of records the mean diurnal range of the tides was 24 5 cm and varied most of the reef flat was within 6 cm vertical span just below mean lower low water the highest elevations within this range were exposed above water level for an average of 918 hours per year as compared with 144 hours per year at the lowest elevation most exposures lasted less than 10 hours with a modal duration of 3 5 hours however exposures longer than 12 hours occurred at nearly all elevations in all years exposures of the reef flat were most frequent between february and june and between august and november a pattern apparently caused by a combination of seasonal oscillations of regional sea levels the annual pattern of the solstitial tides and waves generated by seasonal trade winds the fluctuations in water levels apparently affected the abundances of some species of sea urchins on the reef flat populations of lytechinus variegatus and diadema antillarum declined or disappeared from the reef flat during seasons of repeated subaerial exposures but recolonized the habitat in periods of higher water levels although they are reported to suffer heavy mortality during emersion echinometra lucunter and e viridis did not exhibit reductions in abundance that were synchronous with the seasonal exposures of the reef flat

the structural state of the former lower continental crust in calabria s italy in the northern serre s italy a continuous section through a former lower continental crust is exposed schenk 1984 1985 these granulite facies rocks have not been penetratively deformed during their uplift to higher crustal levels therefore they allow to study the structural state of the lower continental crust most rockforming minerals among them ortho and clinopyroxene and cordierite show recrystallization structures quarz basal subgrain boundaries are developed in lower levels of the lower crust and disappear toward higher levels in addition to dimensional orientations of the rockforming minerals the preferred crystallographic orientations of plagioclases cordierite amphibole pyroxenes and rarely quartz reflect the strain orientation of the prograde high t deformation during this deformation the stretching direction was constant nne ssw throughout the exposed lower crustal section shear indicators are rare this points to the fact that deformation has been homogeneous and coaxial flattening there is only a small variation in orientation and strength of textures throughout the exposed lower crust therefore neighbouring layers of different composition rather than different deformation might serve as seismic reflectors in the former lower crust

synchronous uplift of the lower crust of the ivrea zone and of southern calabria and its possible consequences for the hercynian orogeny in southern europe abstract along the border of the adriatic microplate pre alpine granulite facies rocks from the deepest crust are outcropping at only two places in the ivrea zone of the southern alps and in southern calabria in these two areas the main features of the present crustal structures i e overlapping of large continental crustal and upper mantle segments are interpreted as resulting from their hercynian geodynamic evolutions the tilted nearly complete crustal sections in both areas display very similar lithological sequences and experienced a common geological evolution as deduced from petrological and radiometric dates at the end of hercynian time 295 m y the ivrea body and the lower crustal rocks of southern calabria were contemporaneously sheared off from the upper mantle and uplifted into intermediate crustal levels where they slowly cooled during mesozoic time the tectonic uplift was accompanied by granitoid plutonism and andesitic to rhyolitic volcanism which continued after the hercynian uplift considering the presently similar crustal structures and the upper carboniferous and permian geological evolutions along the whole adriatic plate boundary the ivrea zone and southern calabria are used to resolve the pre alpine history of the boundary zone between the adriatic and the central european block the uplift of the lower crustal upper mantle flakes of the adriatic block was due to flat overthrusting of these flakes on the continental crust of central europe the material of the central european crust underthrust subducted thereby melted during the re equilibration of the geotherms which had been disturbed by the subduction process this led to an extensive calc alkaline plutonism and volcanism of crustal origin along the adria boundary in this boundary region the overlying uppermost crustal levels schiefergebirgsstockwerk were synchronously folded asturian phase in response to the overlapping of the deeper crustal levels subsequently to the orogeny the mountain chain was eroded and molasse basins developed on the overthrust adriatic crustal segment during the lower permian in this model the granulite facies flakes of the ivrea zone and of southern calabria are interpreted as pre hercynian lower crustal segments which were thrust into the middle crust during the hercynian orogeny thus giving rise to wave velocity inversions in the crust further it is proposed that similar geodynamic processes have played a role in the genesis of the conrad discontinuity which is present in many parts of the hercynian fold belt but only in the ivrea zone and in southern calabria the crustal discontinuities formed in hercynian time were uplifted to the surface as a result of alpine reactivation of the adriatic boundary zone and due to their special positions in the bends of the alpine apennine maghrebide mountain system according to the present knowledge of the carboniferous paleogeography and of the orogenic evolution on both sides of the adria sufure zone this fault zone was located within the european continent its role during the hercynian orogeny is discussed envisaging two possibilities an a subduction zone or a subfluence zone in the sense of behr and weber

impact of warming events on reef scale temperature variability as captured in two little cayman coral sr ca records the rising temperature of the world s oceans is affecting coral reef ecosystems by increasing the frequency and severity of bleaching and mortality events the susceptibility of corals to temperature stress varies on local and regional scales insights into potential controlling parameters are hampered by a lack of long term in situ data in most coral reef environments and sea surface temperature sst products often do not resolve reef scale variations here we use 42 years 1970 2012 of coral sr ca data to reconstruct seasonal to decadal scale sst variations in two adjacent but distinct reef environments at little cayman cayman islands our results indicate that two massive diploria strigosa corals growing in the lagoon and in the fore reef responded differently to past warming events coral sr ca data from the shallow lagoon successfully record high summer temperatures confirmed by in situ observations 338c surprisingly coral sr ca from the deeper fore reef is strongly affected by thermal stress events although seasonal temperature extremes and mean ssts at this site are reduced compared to the lagoon the shallow lagoon coral showed decadal variations in sr ca supposedly related to the modulation of lagoonal temperature through varying tidal water exchange influenced by the 18 6 year lunar nodal cycle our results show that reef scale sst variability can be much larger than suggested by satellite sst measurements thus using coral sst proxy records from different reef zones combined with in situ observations will improve conservation programs that are developed to monitor and predict potential thermal stress on coral reefs

hurricane ingrid and tropical storm hanna s effects on the salinity of the coastal aquifer quintana roo mexico abstract there is a lack of information on aquifer dynamics in anchialine systems especially in the yucatan peninsula of mexico most of our knowledge is based on spot measurements of the aquifer with no long term temporal monitoring in this study spanning four years 2012 2016 sensors water depth and conductivity salinity were deployed and positioned 9 and 10 m in the meteoric water mass wm close to the transition with the marine wm halocline in 2 monitoring sites within the yax chen cave system to investigate precipitation effects on the salinity of the coastal aquifer the results show variation in salinity 95 mm such as hurricane ingrid 2013 and tropical storm hanna 2014 shows meteoric water mass salinity rapidly increasing approx 6 39 to 8 6 ppt but these perturbations have a shorter duration weeks and days wavelet analysis of the salinity record indicates seasonal mixing effects in agreement with the wet and dry periods but also seasonal effects of tidal mixing meteoric and marine water masses occurring on shorter time scales diurnal and semi diurnal these results demonstrate that the salinity of the freshwater lens is influenced by precipitation and turbulent mixing with the marine wm the salinity response is scaled with precipitation larger more intense rainfall events 95 mm create a larger response in terms of the magnitude and duration of the salinity perturbation 1 ppt the balance of precipitation and its intensity controls the temporal and spatial patterning of meteoric wm salinity

tides and long term modulations in the caribbean sea the tidal signal and its long term variation in the caribbean sea is analyzed on the basis of hourly records from thirteen tide gauges five of which span more than 20 years the seven larger tidal constituents are studied namely the fortnightly term mf diurnal k1 o1 and p1 and semidiurnal m2 s2 and n2 the 18 61 year nodal modulation is clearly identifiable in almost all the examined constituents of lunar origin however its signal in m2 is less clear while it is almost imperceptible in n2 where the 8 85 year cycle caused by the eccentricity of the moon s orbit and the orientation of its major axis variation dominates the long term variability the effect of the nodal variation in the amplitude and phase lag of the various tidal constituents is in agreement within the 95 error limits with the theoretical gravitational estimate with the exception of the 8 85 year cycle in n2 where larger values are found overall in the caribbean the net effect of the low frequency cycles can change the maximum tidal range from 16 5 to 23 5 in a nodal cycle although the caribbean is a micro tidal environment this still results in changes of the range of up to 8 4 cm significant spatially coherent trends are found for the amplitude of s2 2 3 to 8 8 mm cy

tides of mississippi sound and the adjacent continental shelf abstract hourly water level and current data were collected in mississippi sound and the adjacent continental shelf from april 1980 to october 1981 amplitudes and epochs of the principal tidal constituents were calculated for each location the data were used to construct cotidal charts and describe characteristics of the predominant diurnal tide the pattern of the diurnal partial tides on the shelf is explained by reflection of first class waves propagating normal to the coast the period of the k 1 tide equals the inertial period just offshore of mississippi sound the resulting diurnal shelf currents are sverdrup waves with typical speeds of 5 10 cm s 1 the tidal wave is transformed into a rectilinear shallow water wave as it enters the tidal inlets of mississippi sound the form number of the shelf currents changes from 8 5 to 2 1 in the inlets due to enhancement of the semidiurnal currents this is a result of continuity constraints which transform currents in the inlets within mississippi sound the tidal waves shoal and become increasingly progressive in response to bottom friction

elastic wave velocities in rocks from a lower crustal section in southern calabria italy compressional and shear wave velocities vp and vs have been measured on 14 rock samples recovered from a high grade metamorphic terrane in the southern part of the calabrian massif which is considered to represent a continuous section of a former deep continental crust the experiments have been carried out in a cubic anvil apparatus at constant confining pressures up to 600 mpa and temperatures ranging from 20 to 700 c using the ultrasonic transmission technique at 600 mpa the compressional and shear wave velocities range from 6 33 km s 1 to 7 74 km s 1 and from 3 54 km s 1 to 4 30 km s 1 respectively variations in velocity are strongly related to variations in mineralogy both vp and vs increase with increasing amphibole pyroxene garnet and sillimanite content the range of velocities measured in the granulite facies rocks under conditions of lower crustal depth is similar to the range of seismic velocities for the crust beneath calabria importantly the metapelite rocks with intermediate silica and high alumina contents have in situ compressional and shear wave velocities which are equivalent to the mafic rocks or even significantly higher the detected high velocity layer at a depth between 15 and 20 km can be explained by a sequence of garnet cordierite sillimanite gneisses for which actual velocities between 6 6 and 7 6 km s 1 have been determined experimentally

high resolution numerical modeling of tides in the western atlantic gulf of mexico and caribbean sea during the holocene 1 tidal constituents and datums are computed on a high resolution grid of the northwestern atlantic ocean including the gulf of mexico and the caribbean sea a global model is used to determine tidal parameters on a grid with a nominal resolution of 800 800 the global model includes self attraction and loading drag in shallow marginal seas and internal tide drag in the deep ocean simulations are performed at 1000 year intervals during the holocene 10 000 calibrated years before present 10 ka in combination with changes in bathymetry and coastline location derived from a glacial isostatic adjustment model the global model results are then used to force a regional barotropic tidal model the regional model uses an unstructured finite element grid with very high resolution at the coastline the model results reveal significant variations in tidal constituent amplitudes throughout the holocene in the northwestern atlantic semi diurnal components show a strong amplification at around 9 ka while in the gulf of mexico the response is much more muted variations in diurnal tidal parameters are found to be less significant than semi diurnal parameters throughout the model domain changes in tidal range of great relevance to changes in relative sea level rsl are also investigated throughout the holocene the overall structure is similar to the patterns observed in the m2 tide with peak increases of 200 300 relative to present day being observed along the east coast of the united states from 9 to 8 ka finally the high spatial resolution of the regional model allows for the investigation of tidal changes at spatial scales e g individual bays much smaller than in previous studies

a warning system for stromboli volcano based on statistical analysis in this paper we describe a warning system based on statistical analysis for the purpose of monitoring ground deformation at the sciara del fuoco stromboli volcano sicily after a statistical analysis of ground deformation time series measured at stromboli by the monitoring system known as theodoros theodolite and distancemeter robot observatory of stromboli the paper describes the solution adopted for implementing the warning system a robust statistical index has been defined in order to evaluate the movements of the area a fuzzy approach has been proposed to evaluate an ai alarm intensity index which indicates the level of hazard of the sciara del fuoco sliding

mass transport between a semienclosed basin and the ocean maracaibo system 1 field data and three dimensional numerical estuary and lake computer model simulations are used to investigate exchange between lake maracaibo and the gulf of venezuela this exchange occurs along a dredged shipping lane 100 km long and 14 m deep it is driven by a density difference between the lake and gulf and modulated at tidal and subtidal timescales by water level fluctuations in the gulf propagating to the lake at tidal frequencies exchange is modulated by barotropic forcing and nonlinear baroclinic response leading to a severance of high salinity bottom water into seaward and landward segments bottom water in the landward segment is moved lakeward along the shipping lane where it is mixed vertically and flushed out subtidal water level fluctuations in the gulf force barotropic currents along the shipping lane dominating variability of volume and salt flux at timescales of 1 4 weeks the barotropic component of simulated salt flux decreases from the gulf to the lake as depth averaged salinity decreases while simulated baroclinic exchange is only 20 of that predicted by quasi steady two layer hydraulic theory these reductions in salt flux are due to intense mixing that occurs throughout the shipping lane

she analysis for biozone identification among foraminiferal sediment assemblages on reefs and in associated sediment around st kitts eastern caribbean sea and its environmental significance abstract sixteen nearshore 1 m water depth sediment samples termed sample set 1 were collected from the eastern and south western coasts of the south east peninsula sep of st kitts twelve samples termed sample set 2 were taken from nearby fringing 6 17 m and offshore 18 25 m reefs the sample sets were analysed separately using she analysis for biozone identification shebi and diversities and complementarity shebi is a statistical technique that determines abundance biozones abs using the entire vector of species abundances in samples species richness s the information function h and the equitability index e alpha diversity expresses the diversity within an ab while diversity quantifies diversity changes between adjacent abs complementarity assesses the permeability of ab boundaries shebi divided sample set 1 into five abs but did not distinguish separate bays beta diversities reflected the highest and lowest diversities at mosquito bay and south friar s beach frigate bay respectively complementarity was highest between two abs in south friar s bay indicating a close relationship between shoreline sediment and material marginally farther offshore it was lowest between whitehouse and south friar s bays the assemblages along this transect were rich in discorbis rosea for sample set 2 samples were accumulated for shebi by depth shebi distinguished four abs three on the fringing reefs characterised by differing percentages of asterigerina carinata archaias angulatus and amphistegina gibbosa comparison between sample sets 1 and 2 indicates that during storms sediment moves shoreward from the fringing reefs foraminifera show that there is less movement of sediment 63 m from the shoreline sample set 1 to the fringing and deeper reefs

the influence of wind driven currents on the circulation and bay dynamics of a semi enclosed reefal bay wreck bay jamaica abstract investigations into the descriptive hydrodynamics of a semi enclosed reefal bay showed that inner bay waters re circled the reef and particular forcing conditions of wind and tide retarded or enhanced this circulation fringing reef parabola partially enclosing bays are generally accepted as the limit of the bay dynamics the dynamics displayed at wreck bay on the southeast coast of jamaica however showed the reef as the heart of main circulation and therefore the centre of the functioning bay results from field measurements of the spatial and temporal variability in circulation revealed that inner bay water surging from the back reef exited quickly through a gap in the reef channel flow up to 60 cm s 1 diverged on the fore reef then either re entered the back reef to become closed circum reef circulation crc or continued along the fore reef as open crc variation in the wind regime controlled the relative importance of wind or tides to driving circulation and bay emanation wind speeds above 5 m s 1 were found to be the dominant forcing factor and combined with tides accounted for 60 of the variability in crc when the sea breeze developed during early summer and again when the land breeze strengthened during the winter deployment open crc was extended seawards when channel flow currents displayed occasional surges associated with strong wind driven currents combined with similar incident wave approach this led to change in bay dynamics by extreme expansion in bay characteristics the opposite scenario occurred on rare occasions of low tide with wind calms when channel flow reversed into the inner bay and flow over the emergent reef was reduced leading to the most extreme contraction of bay characteristics

petrology of felsic granulites metapelites metabasics ultramafics and metacarbonates from southern calabria italy prograde metamorphism uplift and cooling of a former lower crust

subtidal hydrodynamics in a tropical lagoon a dimensionless numbers approach abstract observations in a tropical lagoon of the yucatan peninsula motivated a non dimensional number analysis to examine the relative influence of tidal stress density gradients and wind stress on subtidal hydrodynamics a two month observation period in chelem lagoon covered the transition from the dry to the wet season chelem lagoon is influenced by groundwater inputs and exhibits a main sub basin central sub basin a west sub basin and an east sub basin subtidal hydrodynamics were associated with horizontal density gradients that were modified seasonally by evaporation precipitation and groundwater discharge a tidal froude number fr 0 a wedderburn number w and a stress ratio s 0 were used to diagnose the relative importance of dominant subtidal driving forces the froude number fr 0 compares tidal forcing and baroclinic forcing through the ratio of tidal stress to longitudinal baroclinic pressure gradient the wedderburn number w relates wind stress to baroclinicity the stress ratio s 0 sizes tidal stress and wind stress s 0 is a new diagnostic tool for systems influenced by tides and winds and represents the main contribution of this research results show that spring tide subtidal flows in the tropical lagoon had log fr 0 0 and log s 0 0 i e driven mainly by tidal stresses advective accelerations neap tides showed log fr 0 0 and log s 0 0 i e flows driven by baroclinicity especially at the lagoon heads of the east and west sub basins however when the wind stress intensified over the lagoon the relative importance of baroclinicity decreased and the wind stress controlled the dynamics log w 0 each sub basin exhibited a different subtidal response according to the dimensionless numbers the response depended on the fortnightly tidal cycle the location and magnitude of groundwater input and the direction and magnitude of the wind stress

ionian basin and calabria arc some new elements from dss data abstract the interpretation of results from a 250 km long seismic refraction traverse recorded using ocean bottom seismometers in the northwestern ionian sea and a fan profile recorded across southern calabria have augmented previous studies by placing additional constraints on the tyrrhenian sea calabria ionian sea transition overlapping branches of pn phases confirm the existence of a thinned crust about 13 km giving rise to the major bouguer anomaly high of the central ionian basin a low average crustal velocity is observed throughout the basin in accordance with the very thick sedimentary cover exemplified by previous seismic surveys a deepening moho may be followed continuously from the centre of the basin to 40 km offshore from calabria where a sudden depth decrease 30 to 20 km is accompanied by a sharp change in the crustal velocity structure the estimated depth of such a shallower moho towards the northwest confirmed by a shot recorded in a fan geometry across southern calabria is in accordance with that found earlier for the southernmost margin of the tyrrhenian basin

evidence of coastal seiche excitation by tide generated internal solitary waves coastal seiches at magueyes island puerto rico occur in distinct fortnightly groups with maximum seiche activity following new and full moon by 7 days the size of the fortnightly groups depends upon the amplitude of the preceding spring tide and upon the caribbean surface water temperature temperature records from the upper thermocline on the slope seaward of the shelf edge off magueyes island indicate the arrival of semidiurnal packets of negative internal solitary waves we suggest that these internal waves are generated by tides in the southeastern caribbean sea and that they are responsible for exciting the coastal seiches this hypothesis is supported by the characteristics of coastal seiching at puerto princesa on palawan island in the philippines which indicate excitation by the sulu sea internal waves reported by apel holbrook and tsai 1980

tidal dynamics in a coupled ocean lake system abstract barotropic tides were studied in the lake maracaibo system venezuela the system consists of two larger water bodies the gulf of venezuela and lake maracaibo connected by the strait of maracaibo and tablazo bay the dominant semi diurnal tide resonates in the gulf and co oscillates roughly 180 out of phase in the lake the narrow strait and shallow bay regulate their dynamical interaction two and three dimensional finite element models are used in conjunction with a fresh analysis of tidal data at seven stations several of which lie in the strait and bay a coupled model of the whole system is necessary to properly interpret these data which show the influence of small scale near field effects superimposed on the larger scale dynamics of the gulf and lake the detailed geometry at the connections with the gulf and the lake also plays a significant role in the local response in the strait and bay co tidal charts are presented for nine major astronomical and shallow water tidal constituents found in the data the velocity structure derived under simple eddy viscosity assumptions is shown to be highly dynamic a characteristic phase lead is found in velocities at depth and near the shore where vertical shear dominates over inertia in the force balance

tides of the caribbean sea analysis of tidal characteristics from 45 gauge locations indicates that the caribbean sea has a microtidal range for the most part between 10 and 20 cm the tide is primarily either mixed semidiurnal or mixed diurnal but a substantial section from puerto rico to venezuela experiences diurnal tides empirical charts of six component tides m sub 2 s sub 2 n sub 2 k sub 1 o sub 1 and p sub 1 show local detail of phase and amplitude each of the semidiurnal component tides is characterized by anticlockwise rotating amphidromes centered in the eastern caribbean there is evidence of strong radiational forcing of the s sub 2 tide in the south western caribbean the diurnal component tides are largely uniform in both phase and amplitude for most of the western and central caribbean however the diurnal phases increase rapidly towards the northwest and the yucatan channel

a seismic reflection refraction experiment across the exposed lower crust in calabria southern italy first results exposed crystalline basement of the serre mountains in calabria presents a tilted block of a nearly complete section of the hercynian continental lower crust hclc in addition to petrological and structural data from surface mapping and petrophysical data from the laboratory a seismic reflection refraction experiment was conducted in may 1990 this consisted of a 40 km long n s profile crossing the hclc and of four short transverse profiles each recorded using 3 component receivers with an 80 m spacing and explosive sources the reflectivity of the outcropping lower crustal units is lower than theoretically predicted from the observed compositional layering a low velocity zone outcropping in the north and dipping to the south marks the contact between the hclc and the underlying alpine metamorphic units below this zone the deeper crust appears well structured by strong and continuous discrete reflections down to 6 5 8 s t w t presumably the crust mantle boundary at 19 24 km depth with a dominant dip toward the south analysis of refracted wave velocities reveals values systematically lower by up to 30 than laboratory data on rock samples or calculated data from modal analysis this discrepancy can only partly be explained by the effect of microcracks 10 the underestimation of the amount of leucosomes 2 5 and the effect of seismic anisotropy 0 5 the remaining discrepancy must be attributed to large scale alteration of the rocks due to apennine tectogenetic events

lower crustal petrology from wide angle p and s wave measurements in the black forest abstract the lower crust of the black forest in southwest germany is strongly reflective for compressional waves but almost non reflective for shear waves if the reflectivity for p waves is caused by alternating high and low velocity rocks the s wave observations require that the low velocity rocks have a low poisson s ratio and vice versa a purely compositional petrological model for lower crustal rocks can fit the observed p and s wave velocity data provided a rather high quartz content 50 is acceptable for the lower crust

seismological studies at parkfield i simultaneous inversion for velocity structure and hypocenters using cubic b splines parameterization a model for the 3d p and s wave velocity structure at parkfield has been developed by the systematic inversion of arrival times for microearthquakes and surface vibroseis sources recorded by nearby calnet stations and by the local borehole installed 10 station high resolution seismic network there a modification of the linear b splines model parameterization method of thurber 1983 to a cubic b splines formulation through tests inverting synthetic data sets for the parkfield configuration is found to produce smooth velocity distributions that still retain some small scale features application of the method to 953 p wave and 288 s wave arrivals from 111 microearthquakes and 8 vibroseis locations throughout the study area yields a velocity structure having variable resolution a low velocity zone appears to coincide with the creeping segment of the san andreas fault zone northwest of the 1966 parkfield earthquake epicenter an increase of about 15 per cent in seismic velocities is seen from the northeast to southwest across this segment of the fault zone the higher velocities to the southwest apparently correspond to the granitic basement the contrast across the fault is subdued to the southeast along the 1966 rupture zone a high vp vs ratio of 1 9 is seen in a 2 km wide volume near the location of the 1966 main shock hypocenter presumably the nucleation zone for the expected m 6 parkfield earthquake