Open Seawater Research Articles

Пространственное распределение ихтиопланктона у Крымского полуострова в летний сезон 2013 г.

Проанализированы данные, полученные в пяти комплексных экспедициях НИС «Профессор Водяницкий», которые были проведены с мая по сентябрь 2013 г., в летний нерестовый сезон. Представлена динамика видового разнообразия и пространственного распределения ихтиопланктона в связи с особенностями гидрологического режима в различных районах шельфовых и открытых вод Чёрного моря у Крымского полуострова. В ихтиопланктоне идентифицированы 17 видов икринок и личинок рыб из 13 семейств. Количество видов в ихтиопланктоне было максимальным в июне. Средняя численность икринок и личинок за нерестовый сезон составляла 50,5 и 9,2 экз.·м-2 соответственно. Наибольшая численность икринок (109,9 экз.·м-2) и личинок (9,2 экз.·м-2) наблюдалась в июле. Преобладали икринки и личинки хамсы Engraulis encrasicolus (Linnaeus, 1758): их доля в открытых водах в разгар нерестового сезона достигала 96 и 94 % соответственно. Максимальные показатели индексов видового разнообразия и выровненности (значимости каждого вида) наблюдались в мае, когда доминантные виды только начинали нерест и их численность в ихтиопланктоне была сравнительно низкой. Индексы видового богатства достигали наибольших величин в июне, когда количество видов в ихтиопланктоне было максимальным. Видовой состав и пространственное распределение ихтиопланктона зависели от термогидродинамической структуры морских вод в районах исследований, а выживанию личинок рыб способствовало снижение прессинга желетелого планктона на их кормовую базу. Наиболее значимыми факторами, определяющими термогидродинамическую структуру моря в летний нерестовый сезон 2013 г., являлись: региональные особенности режима прогрева поверхности моря в весенне-летний период и его выхолаживания в осенний гидрологический сезон; адвективный вклад поверхностных течений (прежде всего Основного черноморского течения); сгонно-нагонные процессы в прибрежных районах; локальные термохалинные неоднородности в областях смешения распреснённых речных вод с шельфовыми в северо-западной части моря и азовоморских вод в Керченском предпроливье — с водами открытого моря.

Enrofloxacin Pharmacokinetics and Sampling Techniques in California Sea Hares (Aplysia californica).

This pharmacokinetic study was designed to determine the pharmacokinetics of enrofloxacin at 5 mg/kg when given to sea hares in their hemolymph. Enrofloxacin is a commonly used antimicrobial in veterinary medicine and potentially could be used to treat sea hares exposed to susceptible bacterial species. We individually identified 8 juvenile Aplysia californica and group housed them in an open seawater flow system at 14 to 18 °C; 2 served as untreated controls. The remaining 6 animals were injected into the hemocoel with 0.030 mL of 22.7 mg/mL enrofloxacin (average dose, 5 to 6 mg/kg). At each time point, 300 μL hemolymph was collected from the pedal hemolymph sinus and HPLC-analyzed for enrofloxacin and ciprofloxacin levels. Enrofloxacin was detected in all dosed animals, at an average peak concentration of 3 μg/mL in hemolymph, and remained in the body for 20.3 h with an average clearance of 0.19 μg × h/mL. No ciprofloxacin was detected in any Aplysia in this study. Hemocoel injection appears to be an effective way to administer enrofloxacin to Aplysia and reach clinically relevant concentrations. Enrofloxacin reached therapeutic target concentrations in A. californica when dosed according to the regimen described in the current report.

Monitoring von Giftstoffen im Meer

The seas worldwide are threatened by a “new” source of pollution: Millions of tonnes of all kind of munition that have been dumped after World War II will corrode and start to leak. As part of a BMBF funded consortium we are establishing an open sea water program to monitor contaminations of the marine ecosphere by using passive samplers and the mussel Mytilus edulis. The data derived will be important to address the safety of the marine ecosphere, marine fishery resources and, finally, the health of human sea food consumers.

DOM dynamics in open waters of the Mediterranean Sea: New insights from optical properties

In the Mediterranean Sea (Med Sea), Dissolved Organic Matter (DOM) dynamics shows some peculiarities that can be investigated by using its optical properties. Despite being a marginal sea, the Med Sea behaves as a miniature ocean for DOM concentrations and distribution. Its surface waters are “greener” than it would normally result from their generally low phytoplankton content and in the deep waters DOC is ~1000 years older and more degraded than in the Atlantic Ocean. These observations suggest a greater contribution of allocthonous substances to the DOM pool in this basin. With this work we aim at presenting new data on optical properties of chromophoric DOM (CDOM) and fluorescent DOM (FDOM) in open sea waters of the Med Sea, in order to investigate the main drivers of CDOM and FDOM dynamics in both surface and deep waters and to get insights into their origin.Our data confirm the occurrence of DOM with a different composition with respect to the oceans and suggest some differences with respect to other marginal basins, opening intriguing questions about the source and cycle of allocthonous molecules in the open sea waters of the Med Sea. CDOM absorption in the western Med Sea and Ionian Sea is generally lower than that observed in the other marginal seas, but higher than in the oceans. The parallel factor analysis unveiled the presence of one PAH-like and one terrestrial humic-like component that were found in the other marginal basins but that were not found in the open oceans. In contrast to the oceans and most of the marginal seas, only one protein-like component was found. Net production of humic-like FDOM as function of mineralization was not observed in the intermediate and deep waters of the Med Sea, supporting that in this basin CDOM/FDOM dynamics is different than in the oceans. In the surface layer, photobleaching plays a relevant role in the removal of humic-like fluorescence, and the release of both protein-like and humic-like substances occurs in proximity of the deep chlorophyll maximum.

Off-line preconcentration and inductively coupled plasma sector field mass spectrometry simultaneous determination of Cd, Co, Cu, Mn, Ni, Pb and Zn mass fractions in seawater: Procedure validation

Despite the ongoing reduction of emissions of contaminants into the environment, the ocean still represents the most anthropogenically impacted ecosystem worldwide. Sound strategies for marine chemical monitoring call for measurement systems capable of producing comparable analytical results with demonstrated quality. An analytical procedure for simultaneous measurements of the Cd, Co, Cu, Pb, Mn, Ni, Pb and Zn mass fractions in open ocean waters was validated. Procedure validation, including systematic combined uncertainty estimations on measurement results, and the traceability of data are described and explained. Off-line analytes pre-concentration and matrix separation was performed with the commercially available automated seaFAST-pico™ system, followed by inductively coupled plasma sector field mass spectrometry (ICP-SFMS) mass fractions determination. The validation approach applied in the present study is in line with the requirements of ISO/IEC 17025 standard and Eurachem guidelines. Selectivity, working range, linearity, recovery (from 93% to 100%, obtained using the NASS-6 CRM from NRC, Canada), repeatability (1.5–3%), intermediate precision (2–%), limits of detection (0.00006–0.004 μg kg−1) were systematically assessed. The relative expanded uncertainties obtained were at range from 7.0% to 14.0% (k = 2). Excellent results were obtained when applying this procedure to the NASS-7 CRM from NRC, Canada. The potential of this analytical procedure was also tested on open seawater samples from different regions of the world. The validated procedure was applied for the characterisation of the ERM®-CA403 candidate certified reference material and obtained results submitted as the IAEA contribution to this certification.

The role of the estuarine zone on the river particulate toxicity.

Annually, a great volume of sediment and suspended particulate matters (SPMs) enters into the seas through estuaries. In the estuarine zone, metals present in SPMs may undergo conservative or non-conservative changes. In the present study, oxidation-reduction potential (ORP) as the most complex chemical parameter of open sea water and its relationship with the behavior of t metals in the estuarine area were investigated. Dissolved oxygen was used as a strong oxidant to increase the ORP. According to the absorption and desorption experiment, Mn and Cu are desorbed from SPMs during estuarine mixing. However, Zn and Pb are absorbed into the SPMs. In addition, the analysis results were indicative of the conservative behavior of Ni. The results of the three-step chemical partitioning of the SPMs revealed that Mn and Cu are desorbed from the SPMs physically, whereas Zn is absorbed into the SPMs chemically. Also, results showed that Pb is physically desorbed from the SPMs, while it is absorbed into SPMs chemically. All metals, except for Ni and Zn, whose reactions with the SPMs are not affected by an increase in the ORP, are affected by the escalation of this parameter.

Cr isotope systematics in the Connecticut River estuary

Stable chromium (Cr) isotopes (expressed in δ53Cr as the deviation of 53Cr/52Cr in samples from the international standard NIST SRM 979) are an emerging paleoredox proxy that has been used to track Earth's redox evolution over a range of timescales. There have been several major advances in our understanding of the Cr isotope system, but we are still developing a basic knowledge of the global Cr isotope mass balance and there are key Cr fluxes with poorly constrained isotopic compositions. The Cr isotope behavior in estuaries is one such poorly constrained aspect of the modern Cr cycle. Therefore, we collected water and suspended particulate samples from the estuary of the Connecticut River, and present the first Cr isotope dataset from a salinity gradient. As pH and salinity increases from brackish to salt water, dissolved Cr increases from 118.1 ± 25.7 ng/kg (1σ, n = 6) to 225.1 ± 26.0 ng/kg (1σ, n = 8), while particulate Cr decreases from 341.3 ± 319.8 ng/kg (1σ, n = 6) to 208.4 ± 364.5 ng/kg (1σ, n = 8); dissolved δ53Cr decreases from 1.30 ± 0.27‰ (1σ, n = 6) to 0.64 ± 0.16‰ (1σ, n = 8), whereas particulate δ53Cr remained stable at 0.11 ± 0.07‰ (1σ, n = 9). These data suggest that Cr is lost from particles to solution when transitioning from brackish to salt water in the Connecticut River estuary. If these observations can be confirmed in other estuaries, estuary systems can potentially enhance riverine dissolved Cr fluxes and thus lower the Cr oceanic residence time, which has important implications for the Cr isotope system as a paleoceanographic redox proxy. There is a clear inverse correlation between dissolved Cr and δ53Cr in the Connecticut River estuary, which yields a Cr isotope fractionation factor of ~0.89‰ that is indistinguishable from previous estimates based on open seawater samples. Large δ53Cr variation in oxygenated open and estuary seawater suggests that marine δ53Cr variations need not necessarily be exclusively tied to Cr(VI) reduction in low oxygen zones. Therefore, interpreting δ53Cr in the sedimentary record requires taking multiple processes into consideration.

An open-ocean assessment of alkenone δD as a paleo-salinity proxy

Abstract Sea surface salinity (SSS) is the least constrained major variable of the past (paleo) ocean but is fundamental in controlling the density of seawater and thus large-scale ocean circulation. The hydrogen isotopic composition (δD) of non-exchangeable hydrogen of algal lipids, specifically alkenones, has been proposed as a promising new proxy for paleo SSS. The δD of surface seawater is correlated with SSS, and laboratory culture studies have shown the δD of algal growth water to be reflected in the δD of alkenones. However, a large-scale field study testing the validity of this proxy is still lacking. Here we present the δD of open-ocean Atlantic and Pacific surface waters and coincident δD of alkenones sampled by underway filtration. Two transects of approximately 100° latitude in the Atlantic Ocean and more than 50° latitude in the western Pacific sample much of the range of open ocean salinities and seawater δD, and thus allow probing the relationship between δD of seawater and alkenones. Overall, the open ocean δD alkenone data correlate significantly with SSS, and also agree remarkably well with δD water vs δD alkenone regressions developed from culture studies. Subtle deviations from these regressions are discussed in the context of physiological factors as recorded in the carbon isotopic composition of alkenones. In a best-case scenario, the data presented here suggest that SSS variations as low as 1.2 can be reconstructed from alkenone δD.

Tensile test analysis of corroded cleaned aged steel specimens

ABSTRACTThe objective of this work is to analyse the influence of corrosion cleaning employing sandblasting, sand-paper cleaning, high-pressure-fresh-water-cleaning and corrosion cleaning by hammering on the mechanical properties of aged steel specimens. Tensile tests of cleaned corroded specimens are carried out. The specimens were cut from steel box girders, corroded in open sea water. The material properties of five groups of corroded specimens are experimentally estimated including the modulus of elasticity, yield stress, tensile strength and total uniform elongation. The trend of mechanical properties is analysed as a function of the degree of degradation and cleaning procedure, identifying that the cleaning treatment of the corroded surface significantly influences the mechanical properties and stress–strain relationships. A multi-criteria decision technique is employed to identify the most suitable cleaning technique accounting for the efficiency of the cleaning process and reducing the scatter in the mechanical properties of the cleaned corroded specimens.

Nutrient Retention in the Swedish Coastal Zone

In this study, the average nutrient filter efficiency of the entire Swedish coastline is estimated to be about 54% and 70% for nitrogen and phosphorus, respectively. Hence, significantly less than half of the nutrient input from land (defined as river discharge and point sources) can be assumed to be exported from coastal waters to the open sea. However, some coastal areas retained more than 100% of the land load and thus, also filter the open Baltic Sea water. These areas with effective filtering of nutrients have low land load per unit coastal area. The filter efficiency was calculated from a 30-years model simulation (1985-2014) of water exchanges and nutrient cycling within the Swedish coastal zone. The average model skill was evaluated to be good or acceptable compared to observations. In addition to the entire Swedish coast, the retention of total nutrient loads in seven larger coastal sub-regions and selected key sites representing different coastal types was also estimated. The modelled long term nutrient retention was found to be associated with the physical characteristics of a water body, such as the surface area, but also the mean depth and residence time of water. In addition, high retention efficiency is associated with high ratio of sediment nutrient content to pelagic nutrient concentrations. On interannual timescales temporal changes in the coastal nutrient pool can have a large influence on perceived nutrient retention. At one site, the phosphorus filter efficiency was actually negative, i.e. the coastal zone transported more phosphorus to the open Baltic Sea than it received from land. The nutrient removal is most efficient close to land, where the area specific retention efficiency is the highest. The variability of both the filter and retention efficiency between coastal regions was found to be large, with a range of approx. 4-1,200% and 0.1-8.5%, respectively.

In situ measurements of micronutrient dynamics in open seawater show that complex dissociation rates may limit diatom growth

In this first in situ study of the dynamic availability of phytoplankton micronutrients, a SeaExplorer glider was combined with Diffusive Gradients in Thin Films and deployed in the Mediterranean Sea. On the basis of their labile metal complex pools, we discovered that Fe and Co can be potentially limiting and Cu co-limiting to diatom growth, contrary to the generally accepted view that phosphorus (phosphate) is the growth limiting element in the Mediterranean Sea. For flagellates and picoplankton, phosphorus remains the main element limiting growth. Our in situ measurements showed that organic complexes of Fe and Cu (>98% of total dissolved concentration), dissociate slower than inorganic complexes of Co, Cd and Ni (>99% of total dissolved concentration being free ions and inorganic complexes). This strengthens the potential growth limiting effect of Fe and Cu versus phosphate, which is present as a free ion and, thus, directly available for plankton.

Comparison of wind and wave climate in open sea and coastal waters

Wind and wave climate is much geographical region and location dependent, affected by local properties of ocean environment. For safety of world-wide sailing ships knowledge about wind and wave conditions is important, not only for open sea, but also in coastal areas. Wind and waves impact ship design, marine operations and they challenge ability of ships to maintain manoeuvrability in sea states. Their characteristics differ in open sea and coastal waters, and recently have got attention within the maritime community due to the issue of the 2013 Interim Guidelines by IMO (International Maritime Organization) where adverse weather conditions to be used in assessment of ship manoeuvrability have been proposed. The present study investigates how realistic the proposed weather conditions are using data from selected ocean locations. It compares open sea and coastal water wind and wave climate applying hindcast data in the analysis. The description of open sea metocean conditions is limited to the North Atlantic while European waters are used as representative for coastal regions. Challenges in providing metocean description for assessment of ship manoeuvrability are discussed and three approaches for doing it are proposed, giving attention to associated uncertainties. The established correlations between wind speed and significant wave height as well as significant wave height and spectral peak period are compared with the ones suggested by the 2013 Interim Guidelines and other existing standards.

Eco-friendly non-biocide-release coatings for marine biofouling prevention

Environmental concerns have been changing the way of looking for solutions to problems. The hydrosphere, together with its biosphere, has been feeling the impact of many pollutants, used for instance in the marine industry for economic reasons or lack of knowledge of their effects. In particular biocides, applied as coatings in paints, are released into the waters becoming toxic and persistent extending their action to an area far beyond the initial coated surface they should protect. In order to minimize these side effects, two biocides, Irgarol (I) and Econea (E), were covalently attached to polyurethane (PU) and foul-release silicone based (PDMS) marine paints through an isocyanate linker. Their antifouling bioactivity was better in PDMS coatings, both for single (Econea) and combined biocides (E/I ratio = 1.5) with contents lower than 0.6 wt%. The treated samples remained almost clean after more than one year immersion in the Portuguese shore of the Atlantic Ocean, and after about 24 weeks under the tropical conditions of Singapore (Fouling rate < 1%). Complementary biofilm adhesion susceptibility tests against Pseudoalteromonas tunicata D2 showed adhesion reduction higher than 90% for PU formulations containing single biocides and close to 100% for PDMS with combined biocides. The eco-toxicity assessment evidenced a low environmental impact, in accordance with the European standards. In addition, shipping field trial tests showed the best antifouling performance for the Econea-based PDMS formulations (E = 0.6 wt%), which remained clean for about nine months in open seawaters, proving the efficacy of this non-release strategy, when applied under dynamic conditions.

Estimating Currents From Argo Trajectories in the Bothnian Sea, Baltic Sea

Argo floats have been used in the environmental monitoring of the Bothnian Sea, a sub-basin of the Baltic Sea, for five years as part of the Finnish Euro-Argo programme. The Bothnian Sea is considered to be an environmentally healthy part of the Baltic Sea because the deep waters of the basin are well-ventilated by inflowing oxygen-rich saltier and heavier surface layer waters of the Baltic Sea proper. Thus the deep water flow is of interest in the Bothnian Sea. In this study, we used Argo float data from six different long-term missions, from 111 to 512 days, to analyze the deep-water flow in the Bothnian Sea where no continuous monitoring of currents exist. We estimated mainly the flow below the expected halocline from the paths of the floats. We analyzed the movements statistically and estimated the error caused by the surface drift of the floats during their stay at the surface by using 3D hydrodynamic model results as reference data. Our results show a cyclonic resultant current in the deep trench of the Bothnian Sea. There seemed to be very little exchange between coastal zone and open-sea waters in deeper layers. The drifting speed of the floats in the deep layers of Bothnian Sea generally was around 2 cm/s but instantaneous speeds of tens of centimeters up to 30 cm/s in the middle-layer (50 dbars) were observed. In the Bothnian Sea deep, the deep trench on the Finnish side of the Bothnian Sea, the vast majority of the observations showed deep currents from south to north, with the same average speed of around 2 cm/s but the instantaneous maximum was smaller at 13 cm/s. Our study indicates that the routine Argo float observations can be used to get information on the deep currents in the basin in addition to traditional hydrographic observations. This helps in improving our understanding of the oxygen dynamics of the bottom layers of the Bothnian Sea, and the living conditions of the benthic phyto- and zooplankton communities there.

Seasonal changes in the abundance and biomass of copepods in the south-eastern Baltic Sea in 2010 and 2011.

BackgroundCopepods are major secondary producers in the World Ocean. They represent an important link between phytoplankton, microzooplankton and higher trophic levels such as fish. They are an important source of food for many fish species but also a significant producer of detritus. In the terms of the role they play in the marine food web, it is important to know how environmental variability affects the population of copepods.MethodsThe study of the zooplankton community in the south-eastern Baltic Sea conducted during a 24-month survey (from January 2010 to November 2011) resulted in the identification of 24 invertebrate species (10 copepods, seven cladocerans, four rotifers, one ctenophore, one larvacean, and one amphipod). Data were collected at two stations located in the open sea waters of the Gulf of Gdansk: the Gdansk Deep (P1) (54°50′N, 19°19′E) and in the western, inner part of the Gulf of Gdansk (P2) (54°32′N, 18°48.2′E). The vertical hauls were carried out with the use of two kinds of plankton nets with a mesh size of 100 µm: a Copenhagen net (in 2010), and a WP-2 net (in 2011).ResultsThe paper describes the seasonal changes in the abundance and biomass of copepods, taking into account the main Baltic calanoid copepod taxa (Acartia spp., Temora longicornis and Pseudocalanus sp.). They have usually represented the main component of zooplankton. The average number of copepods at the P1 Station during the study period of 2010 was 3,913 ind m−3(SD 2,572) and their number ranged from 1,184 ind m−3 (in winter) to 6,293 ind m−3(in spring). One year later, the average count of copepods was higher, at 11,723 ind m−3(SD 6,980), and it ranged from 2,351 ind m−3(in winter) to 18,307 ind m−3(in summer). Their average count at P2 Station in 2010 was 29,141 ind m−3, ranging from 3,330 ind m−3(in March) to 67,789 ind m−3(in May). The average count of copepods in 2011 was much lower at 17,883 ind m−3, and it ranged from 1,360 ind m−3 (in April) to 39,559 ind m−3 (in May).DiscussionThe environmental conditions of the pelagic habitat change in terms of both depth and distance from the shore. Although the qualitative (taxonomic) structure of zooplankton is almost identical to that of the coastal waters, the quantitative structure (abundance and biomass) changes quite significantly. The maximum values of zooplankton abundance and biomass were observed in the summer season, both in the Gdansk Deep and in the inner part of the Gulf of Gdansk. Copepods dominated in the composition of zooplankton for almost the entire time of the research duration. Quantitative composition of copepods at the P1 Station differed from the one at P2 Station due to the high abundance of Pseudocalanus sp. which prefers colder, more saline waters.

Pathways for Pelagia noctiluca jellyfish intrusions onto the Catalan shelf and their interactions with early life fish stages

Abstract This study investigates the possible pathways for Pelagia noctiluca intrusions over the shelf to understand the interactions between jellyfish and fish larvae. To assess how the presence of P. noctiluca may influence populations of Engraulis encrasicolus and Trachurus trachurus, we analyzed the effect of environmental conditions on the abundance and spatial distribution of P. noctiluca, medusae and ephyrae, and early life stages of these two fish species along the Catalan coast. The highest concentrations of P. noctiluca were found offshore, all along the Northern Current path. Their occurrence over the shelf was associated with intrusions of open sea waters that contoured anticyclonic eddies generated by the oscillatory behaviour of the current. Anchovy larvae were found widely over the shelf, but were especially abundant in the north and in waters influenced by the Ebro river. Spatial patterns of anchovy larvae were defined better by physical environmental factors than by the presence of P. noctiluca, whose distribution clearly was determined by the circulation. The differences in environmental conditions controlling the populations of P. noctiluca and E. encrasicolus larvae prevent their general coexistence over the shelf and prey-predator interactions remained limited to the areas affected by offshore intrusions. It is remarkable that the occurrence of T. trachurus larvae and juveniles was limited to locations over the shelf where jellyfish were observed and never offshore. This suggests that the association between fish and jellyfish occur once jellyfish have been advected from offshore towards the shelf, favouring the survival of larvae and juveniles of T. trachurus.

Influence of the Reynolds number on the thermal effectiveness of tubular heat exchanger subjected to electromagnetic field-based antifouling treatment in an open once-through seawater cooling system

Biofouling adhesion on heat exchanger surfaces reduces the thermal effectiveness of the heat transfer process. The main purpose of this work was to investigate the influence of the turbulent flow regime on an electromagnetic field (EMF)-based antifouling (AF) treatment in a tubular heat exchanger cooling seawater system and to determine the resulting effectiveness-number of transfer units (ε-NTU). Experiments were performed for turbulent flow corresponding to Reynolds numbers (Re) of 9504, 14,257, 19,009 and 28,514, which are normal operating conditions for tubular heat exchangers in which biofouling usually occurs. The best ε-NTU value was improved by 14% for the Re of 28,514 compared with the best value for untreated water. Furthermore, the Re assayed were associated with improved heat transfer resistance. The best AF rate was as high as 20% for a Re of 28,514. Additionally, the biofouling film for the case of seawater treated at 28,514 Re flow was thinner, with a lower concentration of solids, which improved the thermal effectiveness. The EMF-based AF treatment has great potential for improving thermal effectiveness and mitigating biofouling in tubular heat exchangers.

Physical connectivity between Pulley Ridge and Dry Tortugas coral reefs under the influence of the Loop Current/Florida Current system

The Pulley Ridge and Dry Tortugas coral reefs are among the most pristine, but also fragile, marine ecosystems of the continental United States. Understanding connectivity processes between them and with surrounding shelf and deep areas is fundamental for their management. This study focuses on the physical processes related to the connectivity of these reefs. Unprecedented in situ time series were used at these specific reef locations, together with satellite observations and numerical simulations, to investigate the dynamics controlling local circulation on the Southwestern Florida Shelf (SWFS) under oceanic influence. The approach of the Loop Current and Florida Current (LC/FC) system to the SWFS slope can induce 0.5 to 1 m/s offshore flows impacting the Pulley Ridge and Dry Tortugas reefs. On the other hand, when the LC/FC system retreats from the slope, onshore flows can carry open-sea waters over the coral reefs. Local formation of cyclonic eddies is possible near the Dry Tortugas reefs in the LC approach case and passage of upstream LC Frontal Eddies is possible in the LC retreat case. Offshore currents ∼1 m/s over the SWFS slope were also found during periods of anticyclonic LC Eddy separation. A novel finding is the shedding and northward propagation of mesoscale anticyclonic eddies from the core of the LC along the West Florida Shelf. Eddy shedding may have a broader effect on the dynamics of the shelf around the study reef areas. Long periods of LC/FC domination over these coral reefs (reaching several weeks to months) are characterized by strong (∼1 m/s) along-shelf currents and continuous upwelling processes, which may weaken the slope stratification and bring colder, deeper waters over the shelf-break and toward the shallower shelf region.

Sponge community of the western Black Sea shallow water caves: diversity and spatial distribution.

Marine caves possess unique biocoenotic and ecological characteristics. Sessile benthic species such as sponges associated with cave habitats typically show a marked zonation from the cave entrance towards the end of the cave. We describe three semi-submerged karstic caves of 50 to 83 m length and 936 to 2,291 m3 volume from the poorly explored cavernicolous fauna of North-East Bulgaria. We surveyed sponge diversity and spatial variability. Eight demosponge species were identified based on morphological and molecular data, of which six are known from the adjacent open sea waters of the Black Sea. Two species, Protosuberites denhartogi van Soest & de Kluijver, 2003 and Halichondria bowerbanki Burton, 1930, are reported from the Black Sea for the first time. The spatial sponge distribution inside the caves is in general similar, but shows some differences in species composition and distribution depending on cave relief and hydrodynamics. The species composition of sponges of Bulgarian caves is found to be different from Crimean caves. An updated checklist of the Black Sea sponges is provided.

Dinamika Proses Sedimentasi di Perairan Muara Sungai Riko, Teluk Balikpapan

&lt;strong&gt;Dynamics of Sedimentation Process at Riko River Estuary, Balikpapan Bay.&lt;/strong&gt; Development of the marine facilities (i.e. port, workshops, laboratories, etc) for Indonesian Research Vessels and National Center for Marine Research in the proposed National Science Technopark (NSTP) Maritime Region at District of Penajam Paser Utara, East Kalimantan Province, needs to understanding the dynamic of waters physical environment. Due to the NSTP-Maritime region located at Riko River as part of Balikpapan Bay waters, it needs an ocean interaction study between open sea (Balikpapan Bay) and Riko River waters. This study used a 2D-Hydrodynamic Model for Riko River and Balikpapan Bay waters and adjacent sea. The model simulated the hydrodynamic conditions on the waters and furthermore predicted the mud transport in September - November 2016 using the river flow and total suspended sediment data collected in November 2016. The model results showed that the average of sediment load movement due to the dynamic of waters at the estuary is ± 4,25 x10-3 kg per second or ± 367,7 kg per day. This preliminary study hopefully can explain the shallowing processes in mouth of Riko River.