Nutrient Enrichments of Waters of "Golfo de San Jose" (Argentina, 42 oS), Growth and Species Selection of Phytoplankton

Abstract. Coastal Patagonian sea waters had been differentially nutrient-enriched to determine (i) the magnitude of the algal biomass supported and (ii) which species were able to best compete for the available nutrients. Nitrogen was found to be the nutrient limiting growth of the natural phytoplankton population. The addition of NO₃ at 25 μg at 1^-1 led to a 10 to 30 μg 1^-1 increase in chlorophyll a in all but those treatments containing trace metal additions. The best yield coefficients were obtained when a chelator (EDTA) was added with NO₃. A pool of nine diatom species were common in the N0₃ supplemented waters and the addition of vitamins along with NO₃ allowed two of the nine species to dominate.     

The Energetic and Nutritional Contribution of Glucose and Glycine Taken up from Natural Sea Water by Adult Marine Mussels

Abstract. The removal of glycine and glucose by freshly collected adult Mytilus edulis was determined using radiolabeled substances added to ambient concentrations of dissolved organic materials in freshly collected natural sea water. Uptake rates were calculated for substrate concentrations of 0.5 μM glycine and 1.0 μM glucose and were compared with the animals' energy and nitrogen demands as measured by oxygen consumption and ammonia excretion rates. Respiration and ammonia excretion rates as well as cither glycine or glucose removal were all determined for the same animals. The mean respiration rate was 670μl O₂ g^-1h^-1, the mean ammonia excretion rate 1.95 μg-at NH₄-g^-1 h^-1. The calculated uptake rates were 0.48 μmol -g^-1-h^-1 for free amino acids and 0.44 μmol-g^-1 h^-1 for free simple sugars. Such uptake rates could have contributed roughly 13% of the mussels' energy requirements or 10% of the mussels' nitrogen requirements assuming the following conditions: 0.5 μM concentration of free amino acids, 1.0μM concentration of simple sugars, uptake of total amino acids at a rate based on a weighted removal rate of glycine, alanine, serine, and glutamic acid, and uptake of simple sugars at a rate equal to that of glucose removal. It is apparent that simple organic substances dissolved in sea water may be of some benefit to mussels, especially when the substances occur in concentrations typical of coastal sea water.     

南海中部上层海洋湍流混合的空间分布特征及参数化模型

通过对2010年5月南海16°N和14.5°N断面的湍流微结构剖面观测资料分析,给出了南海海盆上层湍流混合空间分布特征:在16°N断面上,上层10~400m垂向平均湍动能耗散率ερ在东侧略大于西侧;相反,在14.5°N断面上,西侧ερ均值约是东侧ερ的4倍,其中,西侧110.5°~111°E的ερ的平均值为2.6×10-6 W/m3,东侧118.5°E的ερ仅为5.89×10-7 W/m3。通过分析细结构剪切和湍流混合的相关性,发现剪切是南海中部上层强湍流混合的主要驱动力,揭示了高模态内波破碎可能是湍流混合的主要机制。另外,研究了大洋中的3种参数化模型,发现适用于大洋近海的参数化MacKinnon-Gregg(MG)模型能较好地用浮频和剪切估算南海中部深海区上层湍流耗散率。     

Convection forced by a descending dry layer and low-level moist convergence

A narrow line of convective showers was observed over southern England on 18 July 2005 during the Convective Storm Initiation Project (CSIP). The showers formed behind a cold front (CF), beneath two apparently descending dry layers (i.e. sloping so that they descended relative to the instruments observing them). The lowermost dry layer was associated with a tropopause fold from a depression, which formed 2 d earlier from a breaking Rossby wave, located northwest of the UK. The uppermost dry layer had fragmented from the original streamer due to rotation around the depression (This rotation was also responsible for the observations of apparent descent—ascent would otherwise be seen behind a CF). The lowermost dry layer descended over the UK and overran higher  θ _w   air beneath it, resulting in potential instability. Combined with a surface convergence line (which triggered the convection but had less impact on the convective available potential energy than the potential instability), convection was forced up to 5.5 km where the uppermost dry layer capped it. The period when convection was possible was very short, thus explaining the narrowness of the shower band. Convective Storm Initiation Project observations and model data are presented to illustrate the unique processes in this case.     

Benthic Fluxes of Dissolved Inorganic Nitrogen in a Coastal Lagoon of the Northern Adriatic Sea: an Interpretation of Spatial Variability Based on Sediment Features and Infauna Activity

Abstract. Dark respiration rates, dissolved inorganic nitrogen (DIN) fluxes and nitrification rates were measured at two sites in the microtidal Sacca di Goro lagoon in September 2000. DIN fluxes correlated with the biomass of the dominant macrofauna species (the amphipod Corophium spp. at station Giralda and the polychaete Neanthes spp. at station Faro). Respiration (> 6 mmol O₂ m⁻²h⁻¹) and ammonium fluxes (> 80μmol N m⁻²h⁻¹) were higher at station Giralda despite the lower organic matter content (4.5 %) and lower macrofauna biomass (4 g AFDW m⁻²). At both sites ammonium fluxes were significantly correlated with the biomass of the benthic infauna, but Corophium stimulated ammonium NH₄⁺ fluxes 3-fold compared to Neanthes. The amphipod also enhanced nitrification rates (> 300 μmol N m⁻²h⁻¹) due to the high density of its burrows, the higher NH₄⁺ regeneration rates and the enhanced oxygen supply to the bacteria.     

Hydrometeor structure of a composite monsoon depression using the TRMM radar

This paper addresses the use of a satellite-based radar for obtaining the composite structure (from several monsoon depressions) of the distribution of precipitation elements in the horizontal and the vertical. This composting is based on the use of a simple elliptical layout of coordinates along the major and minor axes of each storm as it passed over north central India. This satellite, called the Tropical Rainfall Measuring Mission (TRMM), carries onboard a microwave instrument known as the Precipitation Radar (PR). The vertical structure of hydrometeors provided by the radar is somewhat of the same quality as the ground-based Doppler radar units. The PR could identify many features such as the melting layers, height of convection, extent of anvils and types of precipitation over different sections of the composited monsoon depression. Furthermore, the asymmetric nature of surface rainfall that intensifies around the composited monsoon depression has also been mapped, which could provide several more details than was possible from other satellite-based estimates. It is found that the most intense precipitation occurs in the south-southwest region of the monsoon depression. The preponderance of stratiform rain and the coverage of fewer deep convective elements, especially over the orographic upslope region, are some other noticeable features obtained using the TRMM PR. The stratiform rain was noted to arise where the melting layers (in the radar reflectivity signatures) were located near 5 km. In those few occasions where tall rain clouds were discernible, the cloud tops were seen to extend all the way from 12 to 15 km. Rainfall amounts across the composite monsoon depression range from 10 to 100 mm d⁻¹. The 3–4 d passage time of one of those disturbances resulted in local rainfall totals of the order of 200–300 min d⁻¹.     

Shallow-Water Gasohydrothermal Vents of Ushishir Volcano and the Ecosystem of Kraternaya Bight (The Kurile Islands)

Abstract. A marine ecosystem in the crater of the Ushishir Volcano (Kraternaya Bight, Yankich Island, the Kuriles) showing gasothcrmal activity was studied for hydrographical, hydrochemical, and biological characteristics. Maximal changes in chemical and biological characteristics were observed in the surface water layer of 0–5 m. This layer had higher water temperature, was saturated with volcanogcnic carbon dioxide (up to 2000 10^-6 torr), ovcrsaturatcd with oxygen (up to 200 %), and contained high concentrations of chlorophyll a. Hydrogen sulfide was found in the surface water layer and at a depth of 15 m in the area of maximal effect of volcanic effluents.
The planktonic community is characterized by high rates of production and destruction of organic matter only in the 0–5 m layer. Daily vertical migrations of the ciliatc Mesodinium rubrum were observed, which caused "red tides".
Bacterial, algobacterial, and diatom mats developed on the bottom of the bight in the zone of gasohydrothermal vents and in areas of volcanic water seeping. The rate of organic matter production in algobacterial mats reached 33.4g C-rrr²-d^-l, chcmolithotrophy predominating. Bottom settlements had high population density and great animal biomass, which reached 10 kg m^-2 in gasohydrothermal fields. They obtain sufficient energy from primary production of microphy-tobenthos, algobacterial, and bacterial mats. Bcnthic species dominant in the bight were not found off the Ushishir Islands.
Some species of macrobenthos inhabiting the Kraternaya Bight differ markedly in size and biomass from the same species found beyond the bight.     

Population Density, Distribution and Consumption Rates of Three Corallivores at Cabo Pulmo Reef, Gulf of California, Mexico

Abstract. The influence of corallivores on coral community structure of eastern Pacific reefs has been considered less important then that of abiotic oceanographic factors. The data that support this assumption, however, are only available for Central American reefs. To assess the role of predation on hermatypic corals in a different regional reef environment, the abundance, spatial distribution and consumption rate of three corallivores: the echinoid Eucidaris thouarsii (Valenciennes), the asteroid Acanthaster planci (Linnaeus) and the teleostean fish Arothron meleagris (Bloch & Schneider), were estimated at Cabo Pulmo reef, Gulf of California, México (23°25' N, 109°25' W). Statistically, the abundances of the species did not change in any sections of the reef (mean values: E. thouarsii , 0.17 indiv. · m⁻²; A. planci , 1.9 indiv. · m⁻²; A. meleagris , 39 indiv. · ha⁻¹). The average daily individual consumption rates of coral were calculated at 1.83 g CaCO₃· m⁻² for E. thouarsii , 118.4 cm² for A. planci , and 16.38 g CaCO₃· m⁻² for A. meleagris , and were lower than those reported for Central American reefs. Considering the mean estimated carbonate production (7.9 kg CaCO₃· m⁻²· a⁻¹), corallivores eliminate less than 4% of the coral standing stock of Cabo Pulmo reef. The low corallivore population density and consumption rates, together with high local coral cover, indicate that corallivores are not key factors determining scleractinian abundance in this marginal reef.     

Synoptic climatology of Northern Hemisphere available potential energy collapses

Three recurring regional patterns of extratropical baroclinic development associated with synoptic‐scale collapses of Northern Hemisphere available potential energy (APE) are identified using a 1979–95 time series derived from the National Centers for Environmental Prediction (NCEP) reanalysis. A time series of the intraseasonal signal (from 1.6 to 180 days) of APE is used to discern an average cycle of approximately 3 days in the APE generation rate d A /d t (referred to as APE depletion rate if negative). An APE depletion event is defined as a fall and subsequent rise in the time series of d A /d t associated with this cycle. We define synoptic‐scale APE collapses as APE depletion events with maximum depletion rates (d A /d t _min) and maximum APE falls (Δ A _min) of less than −0.145× 10⁶ J m⁻² day⁻¹ and −0.280×10⁶ J m⁻², respectively. All are cold season (15 October–15 April) events. APE collapses were classified based on the evolution of regional synoptic patterns during the 2 days centered at the time of d A /d t _min . All are accompanied by deep tropospheric warming. The west Pacific warm surge (Type A) is driven by cyclogenesis over Japan and anticyclogenesis over the west‐central North Pacific. The Bering warm surge (Type B) is associated with an intense southerly flow across the Bering Strait brought on by cyclogenesis near the Kamchatka Peninsula and an intense anticyclone over Alaska. The Atlantic Canada warm surge (Type C) is characterized by an onshore flow of warm air ahead of a continental storm track over eastern North America.     

An Experimental Investigation of the Palatability of Kelp Bed Algae to the Sea Urchin Parechinus angulosus LESKE

Abstract. The relative palatability of 13 algae common in the kelp beds of the west coast of the Cape Peninsula, South Africa, is experimentally investigated with respect to feeding by the sea urchin Parechinus angulosus.
We investigated 2 hypotheses: 1) that this important herbivore would feed selectively on these algae and 2) that Desmarestia firma, one of these algae, would be unattractive to Parechinus on account of the H₂S0₄ in the thallus.
Algal preferences are determined from 3 types of feeding experiment, results of which support our first hypothesis, and allow us to group the algae into 3 arbitrary categories: "preferred", "intermediate", and "non-preferred". To explain these patterns, we measured "relative astringen-cy" of each species (essentially a phenol measurement), and phenol content of 4 species (FOUN-DENIS method). Rates of feeding on single species are negatively correlated with relative astringen-cies (r = 0.76, P = 0.99). The high relative astringency of D. firma is caused by its high (18 % per dry mass) H₂S0₄ content, and it is non-preferred. Our results therefore support our second hypothesis. Other implications of these results are discussed.     

Coral Recruitment and Regeneration on a Maldivian Reef Four Years after the Coral Bleaching Event of 1998. Part 2: 2001–2002

Abstract.  This paper is the follow-up study to a quantitative inventory of stony corals on a Maldivian reef after the bleaching event of 1998 [Loch, K., W. Loch, H. Schuhmacher & W. R. See, 2002; P.S.Z.N.: Marine Ecology, 23 (3): 219–236] covering the years 2001 and 2002, thereby extending the observation period from 1999 to 2002. Data collection was performed as previously in transects on the reef flat, Acropora tables at the reef rim, Porites lobata blocks and one Diploastrea heliopora colony. While between 2000 and 2001 the transects showed a noticeable increase of living scleractinian colonies of 6.1 per m² of reef surface per year, this had slowed to 0.7 per m² per year by 2002. Likewise, the colonisation of dead Acropora tables had changed from a yearly increase of 14.4 colonies per m² of table surface between 2000 and 2001 to a decrease of 9.4 between 2001 and 2002. The main constituent of the regeneration in transects as well as on Acropora tables was Pavona (Agariciidae), whereas Pocilloporidae and Acroporidae were almost completely missing. A new immigrant was Tubastraea micranthus . Continuous growth of regenerates on Porites presented a columnar form, and the growth rate of D. heliopora was reduced between 2001 and 2002. The influence on reef ecology in terms of coral substrate, species differentiation, growth rate changes, interaction with other organisms and the overall prospect of the reef development on a longer timescale is outlined.     

Role of Bacteria in the Carbon and Nitrogen Flow between Water-Column and Sediment in a Shallow Marine Bay (Bay of Piran, Northern Adriatic Sea)

Abstract. The interdependences between phytoplankton standing crop, bacterial biomass and the dissolved organic matter (DOM) pool in the water column were investigated and related to sediment parameters in a shallow marine bay (Bay of Piran, Northern Adriatic Sea) over an annual cycle. Bacterioplankton density varied between 1–10 × 10⁵ cells ml^-1, with lowest density observed in March corresponding to the low Chi a concentrations during this period. Generation times as determined by dialysis incubations ranged between 4h (June) and 82 h (March). Mean bacterial secondary production rates during summer were about 40 mg C m^-1 d^-1 and 5mg C m^-3.d^-1 during winter. With a short time lag, DOM concentrations followed the fluctuation in Chi a.
Sediment oxygen demand measurements revealed a mean mineralization rate of about 260 mg C m^-2 d^-1 during summer and 100–200 mg C m^-2 d^-1 in winter. Sediment bacterial density varied between 10⁸ - 10⁹ cells g (sediment dry wt)^-1 in the top 5 cm sediment layer or, in terms of biomass, 4.3 g C m^-l during summer and 0.6 g C m^-2 during winter. Highest concentrations of DOM in pore waters were measured in September, coinciding with high rates of sediment oxygen demand.     

南极普里兹湾海域湍流扩散系数估计

基于Thorpe尺度方法,利用CTD数据,计算了南极普里兹湾海域的Thorpe尺度和湍流扩散系数,分析了观测区域(64°～69°S,66°～80°E)湍流翻转现象的强弱及分布。结果表明,在海底和地形粗糙区存在较大的Thorpe尺度(较强湍流翻转)和湍流扩散系数,湍流扩散系数最大值能达到10^-2m²/s量级,比平坦开阔海洋高2～3个数量级,部分观测站位的湍流扩散系数和湍动能耗散率表现出大-小-大的垂向分布结构,总水深较深的区域尤为明显;深水区域的浮力频率在海表面到500 m层比较大,浅水区域该现象不明显;湍动能耗散率在(67.25°S,73°E)周围和经度为78°E的各站位都表现相对较大,能达到10^-6 w/kg量级,个别站位甚至能达到10^-5 w/kg量级。     

Nitrogen Assimilation and Partitioning in the Mediterranean Seagrass Posidonia oceanica

Abstract. The supply of nitrogen (N) often limits the productivity of marine macrophytes. In vitro and in vivo assays of glutamine synthetase (GS) activity were employed to investigate patterns of N assimilation by the Mediterranean seagrass Posidonia oceanica (L.) DELILE. Biomass-specific GS activity wa measured in root tissue, in leaves within a shoot, in shoots collected at two sites during two season and over a depth range of 5–33 m. Root tissue was less important than shoot tissue in assimilating inorganic N in P. oceanica , due both to the small roots' biomass (ca. 3% of total plant biomass and greatly lower (10- to 50-fold) GS activities. While the GS activity and N assimilatory potentia (biomass × GS activity; μmol N-h-^-1) were greatest in leaf 2, leaves 1 and 3–5 assimilated N a significant rates. Shoots from a site characterized by elevated N availability in the winter water column and no significant sediment N reservoir exhibited GS activities that were 9-times higher than shoot from a more oligotrophic site. Shoot GS activities in July increased linearly from 5 to 33 m and wer correlated with light availability as defined by H^sat, (daily period during which photosynthetic reaction are light-saturated). This may represent metabolic compensation by P. oceanica to maintain N influx. Factors contributing to the ecological success of P. oceanica include the ability to assimilate N under conditions of severe light limitation (< 35 μmol photons. m^-2. s^-1), and metabolic plasticity to ensur the de novo generation of N-containing organic compounds.     

夏季长江河口层化与湍流混合特征分析

利用2016年夏季长江河口现场水文特性与湍流微结构观测资料, 分析了长江河口水体温盐结构、层化发育、湍流与混合特征。结果表明: 1)夏季长江河口水体密度层化结构明显, 根据各层水体密度梯度差异, 可将水体分为底部混合层和上层密度跃层, 两部分的密度层化界限与浮力频率等值线lg N ² = - 4.0接近。2)底部混合层湍动能耗散率大, 层化结构弱, 水体分层稳定性弱; 上层密度跃层湍动能耗散小, 层化结构强, 水体分层稳定性强, 这有利于河口内波的发育与传播。3)在密度层化的作用下, 水体的湍动能耗散率、湍动能剪切生成及浮力通量的能量关系在一定范围内符合湍动能局部能量平衡方程。不同层之间的湍流弗劳德数Fr_t和湍流雷诺数Re_t在Fr_t-Re_t平面上呈现明显的分区, 与经典的分层剪切流理论基本吻合。     

Ideal shocks in 2‐layer flow Part II: Under a passive layer

In this second part of the study, ideal shock theory in two‐layer stratified flow is extended to include a third passive layer (i.e., a two and a half layer system). With the presence of a passive layer, two linear wave modes and "viscous tail modes" exist, complicating the solubility conditions and uniqueness proofs for two layer shocks. It is found however, that shocks can be unambiguously classified as external or internal based on the states of criticality that they connect. The steepening condition, while still necessary, provides a less restrictive constraint than it did with a rigid lid. Thus, we have to rely more on solutions to the full viscous shock equations to establish shock existence. The detailed structure, momentum exchange, and Bernoulli loss in a viscous shock are examined using an analytical weak shock solution and a set of numerical solutions for shocks with finite amplitudes. A shock regime diagram ( F ₁ by F ₂) is constructed based on the numerical integration of the full viscous shock equations. For strong external jumps, a cusp region (i.e., in the sense of catastrophe theory) is identified on the regime diagram. For pre‐shock states within the cusp, three end states are possible and two of these are realizable. The cusp has several physical implications. It indicates that an equal distribution of dissipation between the two layers in shocks is mathematically possible but physically inaccessible. It also allows hysteresis in time varying flows, and promotes the occurrence of double shocks (i.e., closely spaced shocks of different character). The results are compared with classical shock solutions and a set of time dependent numerical experiments.     

Altering intertidal sediment topography: effects on biodiversity and ecosystem functioning

Sedimentary marine systems are often highly productive and perform important nutrient regeneration functions as they efficiently decompose organic material. In recent years the role of habitat effects and of species composition in ecosystem functioning has become of interest. Estuarine environments are frequently subject to considerable anthropogenic pressures whilst supporting a variety of habitats ranging from well sorted soft muds through biogenically stable sediments to highly mobile coarse sands. There is therefore considerable spatial complexity in habitat type and faunal composition. This study set out to observe the effects of altering the topographical habitat features of an estuarine mudflat on a range of porewater nutrient concentrations (NH₄⁺, NO₃⁻, NO₂⁻, PO₄³⁻ and SiO) collected from four depths (3, 5, 9, and 12 cm) and on faunal composition. Two treatments (Shelled Nets and Net Controls) were used to alter the topography from simple mud to a mussel shell crumble and were compared to un-manipulated Control areas. Sediment granulometry and organic matter content analyses alongside biological traits analysis of the fauna were also conducted.
Differences were observed in porewater nutrient concentrations between the Control and both netted treatments at 5 cm depth only; the species diversity and abundance were also different in the netted treatments compared to the Controls, although no difference between the two manipulated treatments were observed. The changes in faunal composition were attributed solely to the altered topography and the observed nutrient changes were attributed to the faunal alteration rather than the topographical manipulation.     

Black Sea vertical circulation and extremes of the hydrochemical and hydrooptical parameters

A statistical evaluation of vertical current velocity profiles w(z) has been undertaken using data provided by current meter profilers. The calculation of profiles w(z) involves the estimation of the standard deviation of vertical current at each depth level, and the standard deviation of the statistical variability of that estimate. Profiles w(z) have been computed for the northwestern Black Sea, using current meter and CTD data from three surveys carried out during 1992–1994. The calculations show w(z) to have a two-layered structure, with zero values occurring in the main pycnocline. Such vertical current structures are consistent with a hydrodynamic model, whereby the current field is induced by buoyancy fluxes through the lateral basin boundaries. Existence of zero vertical current velocities at the pycnoclines yields the key to understanding the mechanisms responsible for the oxic-anoxic interface, and of the zones with steep vertical gradients in hydrochemical and hydrooptical characteristics.     

States of maximum entropy production in a one-dimensional vertical model with convective adjustment

We investigate the hypothesis that the atmosphere is constrained to maximize its entropy production by using a one-dimensional (1-D) vertical model. We prescribe the lapse rate in the convective layer as that of the standard troposphere. The assumption that convection sustains a critical lapse rate was absent in previous studies, which focused on the vertical distribution of climatic variables, since such a convective adjustment reduces the degrees of freedom of the system and may prevent the application of the maximum entropy production (MEP) principle. This is not the case in the radiative-convective model (RCM) developed here, since we accept a discontinuity of temperatures at the surface similar to that adopted in many RCMs.
For current conditions, the MEP state gives a difference between the ground temperature and the air temperature at the surface ≈10 K. In comparison, conventional RCMs obtain a discontinuity ≈2K only. However, the surface boundary layer velocity in the MEP state appears reasonable (≈m s⁻¹). Moreover, although the convective flux at the surface in MEP states is almost uniform in optically thick atmospheres, it reaches a maximum value for an optical thickness similar to current conditions. This additional result may support the maximum convection hypothesis suggested by Paltridge (1978 ).