Artificial Tide Research Articles

Experimental reductions in subdaily flow fluctuations increased gross primary productivity for 425 river kilometers downstream.

Aquatic primary production is the foundation of many river food webs. Dams change the physical template of rivers, often driving food webs toward greater reliance on aquatic primary production. Nonetheless, the effects of regulated flow regimes on primary production are poorly understood. Load following is a common dam flow management strategy that involves subdaily changes in water releases proportional to fluctuations in electrical power demand. This flow regime causes an artificial tide, wetting and drying channel margins and altering river depth and water clarity, all processes that are likely to affect primary production. In collaboration with dam operators, we designed an experimental flow regime whose goal was to mitigate negative effects of load following on ecosystem processes. The experimental flow contrasted steady-low flows on weekends with load following flows on weekdays. Here, we quantify the effect of this experimental flow on springtime gross primary production (GPP) 90-to-425km downstream of Glen Canyon Dam on the Colorado River, AZ, USA. GPP during steady-low flows was 41% higher than during load following flows, mostly owing to nonlinear reductions in sediment-driven turbidity. The experimental flow increased weekly GPP even after controlling for variation in weekly mean discharge, demonstrating a negative effect of load following on GPP. We estimate that this environmental flow increased springtime carbon fixation by 0.27g C m-2 d-1, which is ecologically meaningful considering median C fixation in 356US rivers of 0.44g C m-2 d-1 and the fact that native fish populations in this river are food-limited.

Improvement of the coral growth and cost-effectiveness of hybrid infrastructure by an innovative breakwater design in Naha Port, Okinawa, Japan

ABSTRACT Hybrid infrastructure combining gray and green infrastructure should be more cost-effective than gray infrastructure; however, its cost-effectiveness and cost-effective methods for its construction are not clear. Here we used pro-environment breakwaters, having the original breakwater function of wave attenuation along with the additional function of providing marine-life habitats, as a model for estimating the cost-effectiveness of hybrid infrastructure. We defined effectiveness as the area of coral cover on the breakwaters. We compared coral areas between a normal (control) breakwater, and pro-environment breakwaters (PBs) with artificial tide pools (ATPs) at shallow depth (PBshallow) or ATPs at deeper depth (PBdeep). The coral area increased by ~10% on PBshallow and ~20% on PBdeep compared to the control. PBdeep had the largest increase in coral area, resulting from the installation of ATPs, which accounted for ~40% of the increase in coral area. PBdeep, with greater breakwater surface area and ATPs at depths more appropriate for corals than PBshallow, increased the cost-effectiveness by ~10% compared to the control. Our finding that the cost-effectiveness of ATP installation is comparable to that of coral transplantation to natural reefs suggests that ATPs are cost-effective for coral habitat restoration.

Research on Hydrodynamics with Water Temperature Characteristics and Spring Algal Blooms in a Typical Tributary Bay of Three Gorges Reservoir

After the impoundment of the Three Gorges Reservoir (TGR) in China, water environment problems induced by water temperature stratification in the Xiangxi Bay (XXB, a typical tributary bay of TGR) received wide attention. In this study, a 3-dimensional (3D) hydrodynamic and water temperature coupled model with the z-coordinate in the vertical direction was established with Delft3D software to simulate the continuous hydrodynamic and water temperature process of XXB in 2009, and the static stability and mixing depth were also analyzed. The results show that the upstream inflow is prevented from entering TGR with nutrients enriching and mixing in the upper and middle reach of XXB from winter to early spring, which is the primary cause of spring algal blooms in XXB. Therefore, measures such as improving the upstream hydrodynamic conditions and forcing the nutrients to flow into TGR in winter should be more effective in alleviating spring algal blooms than the artificial tide operation of TGR proposed by previous studies.

Quantification of the foraging activity of Patella caerulea and P. rustica under simulated tides using photographic analysis of radula scratches

Quantification of the foraging activity of Patella caerulea and P. rustica under simulated tides using photographic analysis of radula scratches

Modelling, simulation and real-time control of a laboratory tide generation system

Small-scale experiments allow to reproduce and understand phenomena and to draw inferences about large-scale processes. In this paper, we consider a peculiar experimental apparatus which is aimed at reproducing a typical lagoonal environment subject to tidal forcings. This apparatus is useful for performing morphometric analyses of synthetic tidal networks. The quality of these kind of experiments strongly depends on the behaviour of the artificial tide that has to exhibit predefined characteristics. To this aim, the height of the artificial water wave is controlled in real-time. The experimental apparatus has an intrinsic complexity and it represents an example of a multi-domain physical system. In order to design and to assess suitable control strategies, we have developed a Matlab-based simulation environment which is able to reproduce the behaviour of the artificial tide generation system. The dynamic model is calibrated and validated by using real experimental data and it can be seen as an extremely useful tool in the decision making process of the real control system development. In particular, we have designed, tuned, and tested a model-free control algorithm, that is the intelligent-PI (i-PI). Finally, the proposed controller has been implemented on a real-time hardware and then its performance has been compared with that of a standard regulator for different type of experiments.

Modelling and Simulation of an Artificial Tide Generation System

In this paper we consider a small-scale experimental apparatus that allows to reproduce and understand phenomena in large-scale typical lagoonal environments and to draw inferences about channel network ontogeny and evolution. In particular, the device reproducing the artificial tide is the core of the experimental apparatus and it is controlled in real-time to satisfactorily reproduce the natural phenomena. The experimental apparatus has an intrinsic complexity and it represents an example of a multi-domain physical system (electrical, mechanical, and hydraulic). In order to design and to asses suitable control strategies, we develop a Matlab-based simulation environment which is able to reproduce the behaviour of the artificial tide generation system. In particular, we use a hybrid modelling technique which integrates casual and acausal approaches. Finally, the dynamic model is calibrated and validated by using real experimental data. The developed model represents a good trade-off between accuracy and complexity and it is useful for control system development purposes.

Model-free Control of an Artificial Tide Generation Experimental Apparatus

Small-scale experiments allow to reproduce and understand phenomena and to draw inferences about large-scale processes. In this paper, we consider a peculiar experimental apparatus which is aimed at reproducing a typical lagoonal environment subject to tidal forcings. This apparatus is useful for performing morphometric analyses of synthetic tidal networks. The quality of these kind of experiments strongly depends on the behaviour of the artificial tide that has to exhibit predefined characteristics. To this aim, the height of the artificial water wave is controlled in real-time. Due to the intrinsic complexity of the system, the development of a control algorithm as simple as possible but able to ensure suitable control performance over a wide range of operative conditions, is a non-trivial task. In this paper, we have developed and tested a model-free control algorithm, that is the intelligent-PI (i-PI). Finally, the performance of the i-PI controller are compared with those of a standard regulator for different type of experiments.

Influence of artificial tides in Ucides cordatus innate immune system

Influence of artificial tides in Ucides cordatus innate immune system

Local tidal regime dictates plasticity of expression of locomotor activity rhythms of American horseshoe crabs, Limulus polyphemus.

While horseshoe crabs Limulus polyphemus from regions with two daily tides express endogenous circatidal (~ 12.4 h) activity rhythms, much less is known about locomotor rhythm expression in horseshoe crabs from other tidal regimes. This study investigated whether horseshoe crabs (1) always express activity rhythms consistent with their natural tides, and (2) can alter activity rhythm expression in response to novel tide cycles. Activity rhythms of animals from environments with two daily tides (Gulf of Maine, 43°6' N/70°52' W, and Massachusetts, 41°32' N/70°40'W), one dominant daily tide (Apalachee Bay, Florida, 29°58' N/84°20' W), and microtides (Indian River Lagoon, Florida, 28°5' N/80°35' W) were recorded in 2011-2013 during three artificial tide conditions: no tides, a 12.4 h tidal cycle, and a 24.8 h tidal cycle. Interestingly, L. polyphemus from the microtidal site (n = 7) appeared "plastic" in their responses; they were able to express both bimodal and unimodal rhythms in response to different tide cycles. In contrast, the other two populations exhibited more fixed responses: regardless of the tides they were exposed to, animals from areas with one dominant daily tide (n = 18) consistently expressed unimodal rhythms, while those from areas with two daily tides (n = 28) generally expressed bimodal rhythms. Rhythms expressed by L. polyphemus thus appear to be a function of endogenous clocks, the tidal cues to which animals are exposed, and tidal cues that animals experience throughout ontogeny.

Entrainment of juvenile horseshoe crab activity to artificial tides

Juvenile American horseshoe crabs, Limulus polyphemus, express both daily and tidal rhythms. To determine if, and how, tidal cues influence the expression of these rhythms, we exposed 25 animals to artificial tides, and 17 to artificial tides with inundation, both with a 12:12 LD cycle. In the first experiment, 24% expressed daily rhythms of activity, 24% tidal rhythms, 12% a combination of the two, and the rest were arrhythmic. Under subsequent atidal conditions some expressed daily rhythms, but more were circatidal. In the second experiment, 6% expressed daily rhythms, 71% tidal, 12% a combination, and 12% were arrhythmic. Those expressing tidal rhythms were more active during flood/high tide, while daily animals tended to be nocturnal. Under subsequent constant conditions, the majority exhibited circatidal activity, with some expressing one activity bout per day. We conclude that juvenile horseshoe crabs entrain to artificial tides, with inundation cycles providing stronger cues than water depth changes.

Opportunistic suspension feeding in the intertidal gastropod Olivella columellaris and its implications for the regulation of tidal migrations

The gastropod Olivella columellaris inhabits sandy beaches of the Tropical East Pacific. These snails perform tidal migrations forcontinuous suspension feeding in the moving backwash zone, possibly controlled by an endogenous circatidal clock. However, O. columellaris readily modifies its circatidal behavior, for example when flow channels develop below natural and artificial tide pools at ebb tide. Suspension feeding continues in such channels while water is running, delaying tidal migration. Such behavioral plasticity questions the significance ofendogenous rhythms for the regulation of tidal migrations in O. columellaris.

Artificial tide generation and its effects on the water environment in the backwater of Three Gorges Reservoir

Since the water impounding of the Three Gorges Reservoir (TGR) in 2003, the water stage in the backwater region increased from 65 m before water impounding to 145 m, and the velocity of the stream flow decreased significantly. The outflows of the tributaries that flow into TGR were also obstructed by the backwater. Stopping the stream flow prevented the pollutants from diffusing and transporting themselves into the water body, hence polluting the water in several tributaries. The authors proposed an artificial tide generation approach to solve this problem. The man-made flood peak in the downstream and the waves of the water stage in the upstream of the TGR can be produced by operating hydropower generators daily to deal with peak-and-bottom variations in the electricity demand. These waves will propagate upwards and form artificial tides in the backwater area. The water stage variation will intensify the flow exchange between the main stem and the tributaries as well as enhance the diffusion of pollutants, which will subsequently decrease the eutrophication of the water body in the outlet of branches as well as relieve the algal bloom problem in the region. The daily operations in the reservoir were simulated and tested by using the proposed hydrodynamic model of TGR. The hydropower operation for the peak load of electricity demand will produce artificial tides in the backwater area of TGR as well as increase the water stage variation from 0.30 m to 0.50 m within a day. This periodic fluctuation of water stage waves will intensify the water exchange between the main reach of Changjiang (Yangtze River) and its tributaries with an additional inflow or outflow of up to 300-500 m(3)/s, which is equivalent to the average discharge of these tributaries during the summer. The artificial tide generation can enhance the internal exchange of backwater as well as improve the water environment condition in the backwater area. This operation approach provides a new technology for controlling the water quality in reservoirs as well as enhances environmental protection and resource utility. Crown Copyright (C) 2015 Published by Elsevier B.V. All rights reserved.

Effect of chronic ammonia exposure on locomotor activity in the fiddler crab Uca princeps upon artificial tides and light cycles

The aim of this study was to evaluate the effect of continuous exposure to sublethal ammonia concentrations upon the characteristics of the locomotor activity rhythms in Uca princeps, exposed to artificial tides and light cycles. Adult male crabs were used for standardized 24 h ammonia acute toxicity tests. Sublethal ammonia concentrations were selected considering the results obtained in the acute bioassays as well as the unusual high ammonia concentrations registered in their natural habitat. Three independent groups of eight crabs each were exposed during 15–20 days to 0.125, 3.5, and 18 mg N-TA/L in artificial sea water. Locomotor activity was recorded individually by means of infrared light crossings. Artificially created tidal and light–dark cycles were used along the experiments. The 24 h-LC50 was 186.02 mg N-TA/L. No mortality was registered in the crabs exposed to the sublethal ammonia concentrations. In control groups, organisms showed tidal activity onset mainly in low tide (ebb) and no response to light cycles while ammonia exposed crabs shifted their onset of activity to high tide, and a general increasing activity was observed along the experiment. The obtained results indicate that ammonia affects the entraining features of the tidal activity rhythm and demonstrate that under ammonia sublethal exposure, tides may present relative coordination with light cycles in the tidal activity rhythm of the crabs.

SOME RECENT FINDINGS IN THE BIOTECHNOLOGY OF BIOLOGICALLY IMPORTANT NUCLEOSIDES

63 Nucleosides embrace a large family of natural and chemically modified analogues of great structural diversity and a broad spect rum of biological activity. Analogues of natu ral nucleosides as well as nucleoside antibio tics belong to the most important classes of antiviral drugs, and they are extensively used in the treatment of a variety of cancers. Base and sugar modified nucleosides are very valuab le constituents of artificial oligonucleo tides of medicinal potential making these oligomers more stable in biological fluids and improving their targeting proper-ties. The chemistry of many antiviral and anticancer drugs, as well as building blocks for oligonucleotide synthesis remains a challenging problem resulting in a high price of the desired compounds preventing them from extensive therapeutic application and use in oligonucleotide business (for a recent reviews, see [1–3]. Analysis of the state of the art of chemoenzymatic synthesis of nucleosides led us to conclusion that the chemo-enzymatic methodo logy demonstrates a number of advantages over the chemical methods of nucleoside synthesis, viz., high total yield of desired pro ducts, simplicity of work-up of reaction mixtur es and isolation of products, conform to the principles of «green chemistry» to a greater extent vs. the fine organic synthesis [1–3]. Up to the present, a vast majority of the modified nucleosides have been synthesized by chemical methods. Despite the impressive progress achieved in the development of chemical methods, production of many antiviral and anticancer drugs, as well as other biologically active compounds remains a challenge. This leads to high drug costs and, therefore, prevents extensive biological trials and studies, as well as a wide therapeutic application. The need for the development of new strategies became apparent in the late 1970s. The chemo-enzymatic (biotechnological) strategies are currently displacing multi-stage chemical processes, and this allows perfor ming the key transformations with high selectivity and regioand stereo-specificity. Considerable progress in the production of biologically important analogs of natural nucleosides has been achieved through the rational combination of chemical and biochemical transformations. Use of recombinant nucleoside phosphorylases (NPs) and N-deoxyribosyl transferases (NDTs) as biocatalysts for the synthesis of natural nucleosides and their modified analogs is of considerable importance UDK 577.113.3

Rhythms of Locomotion Expressed byLimulus polyphemus,the American Horseshoe Crab: I. Synchronization by Artificial Tides

Limulus polyphemus, the American horseshoe crab, has an endogenous clock that drives circatidal rhythms of locomotor activity. In this study, we examined the ability of artificial tides to entrain the locomotor rhythms of Limulus in the laboratory. In experiments one and two, the activity of 16 individuals of L. polyphemus was monitored with activity boxes and "running wheels." When the crabs were exposed to artificial tides created by changes in water depth, circatidal rhythms were observed in animals exposed to 12.4-h "tidal" cycles of either water depth changes (8 of 8 animals) or inundation (7 of 8 animals). In experiment three, an additional 8 animals were exposed to water depth changes under cyclic conditions of light and dark and then monitored for 10 days with no imposed artificial tides. Most animals (5) clearly synchronized their activity to the imposed artificial tidal cycles, and 3 of these animals showed clear evidence of entrainment after the artificial tides were terminated. Overall, these results demonstrate that the endogenous tidal clock that influences locomotion in Limulus can be entrained by imposed artificial tides. In the laboratory, these tidal cues override the influence of light/dark cycles. In their natural habitat, where both tidal and photoperiod inputs are typically always present, their activity rhythms are likely to be much more complex.

Rhythms of Locomotion Expressed byLimulus polyphemus, the American Horseshoe Crab: II. Relationship to Circadian Rhythms of Visual Sensitivity

In the laboratory, horseshoe crabs express a circadian rhythm of visual sensitivity as well as daily and circatidal rhythms of locomotion. The major goal of this investigation was to determine whether the circadian clock underlying changes in visual sensitivity also modulates locomotion. To address this question, we developed a method for simultaneously recording changes in visual sensitivity and locomotion. Although every animal (24) expressed consistent circadian rhythms of visual sensitivity, rhythms of locomotion were more variable: 44% expressed a tidal rhythm, 28% were most active at night, and the rest lacked statistically significant rhythms. When exposed to artificial tides, 8 of 16 animals expressed circatidal rhythms of locomotion that continued after tidal cycles were stopped. However, rhythms of visual sensitivity remained stable and showed no tendency to be influenced by the imposed tides or locomotor activity. These results indicate that horseshoe crabs possess at least two biological clocks: one circadian clock primarily used for modulating visual sensitivity, and one or more clocks that control patterns of locomotion. This arrangement allows horseshoe crabs to see quite well while mating during both daytime and nighttime high tides.

The recognition of ocean red tide with hyper-spectral-image based on EMD

A new technique is introduced in this paper regarding red tide recognition with remotely sensed hyper-spectral images based on empirical mode decomposition (EMD), from an artificial red tide experiment in the East China Sea in 2002. A set of characteristic parameters that describe absorbing crest and reflecting crest of the red tide and its recognition methods are put forward based on general picture data, with which the spectral information of certain non-dominant alga species of a red tide occurrence is analyzed for establishing the foundation to estimate the species. Comparative experiments have proved that the method is effective. Meanwhile, the transitional area between red-tide zone and non-red-tide zone can be detected with the information of thickness of algae influence, with which a red tide can be forecast.

한강 본류에의 적용을 위한 FLDWAV 모형의 개선

FLDWAV model was modified such that it can adequately simulate the effect of Jamsil and Singok submerged weirs in the main reach of the Han River. The enhanced model combines weir-type discharge equations for overflow at fixed weir and Manning equation for fluvial-type flow at the movable weir. Equations for weir overflow include those for submerged weir flow and free overflow. Gates of the movable weir may be open or closed for the simulation. In order to test the simulation capabilities, the enhanced model was applied for various flow conditions at submerged weirs. Backwater effect due to Jamsil and Singok submerged weirs were well simulated. Simulations were carried out for spring and neap tides extracted from artificial tide generated by combining tidal constituents. Simulation results cleared indicated that tidal effect extends further upstream as the flood discharge decreases. Low flow simulation capabilities of the enhanced model was tested. Discontinuities of water surface elevation due to the submerged weirs were successively simulated.

INVERTEBRATE‐MEDIATED NUTRIENT LOADING INCREASES GROWTH OF AN INTERTIDAL MACROALGA1

Even in nitrogen‐replete ecosystems, microhabitats exist where local‐scale nutrient limitation occurs. For example, coastal waters of the northeastern Pacific Ocean are characterized by high nitrate concentrations associated with upwelling. However, macroalgae living in high‐zone tide pools on adjacent rocky shores are isolated from this upwelled nitrate for extended periods of time, leading to nutrient limitation. When high‐intertidal pools are isolated during low tide, invertebrate‐excreted ammonium accumulates, providing a potential nitrogen source for macroalgae. I quantified the influence of mussels (Mytilus californianus Conrad) on ammonium accumulation rates in tide pools. I then evaluated the effects of ammonium loading by mussels on nitrogen assimilation and growth rates of Odonthalia floccosa (Esp.) Falkenb., a common red algal inhabitant of pools on northeastern Pacific rocky shores. Odonthalia was grown in artificial tide pool mesocosms in the presence and absence of mussels. Mesocosms were subjected to a simulated tidal cycle mimicking emersion and immersion patterns of high‐intertidal pools on the central Oregon coast. In the presence of mussels, ammonium accumulated more quickly in the mesocosms, resulting in increased rates of nitrogen assimilation into algal tissues. These increased nitrogen assimilation rates were primarily associated with higher growth rates. In mesocosms containing mussels, Odonthalia individuals added 41% more biomass than in mesocosms without mussels. This direct positive effect of mussels on macroalgal biomass represents an often overlooked interaction between macroalgae and invertebrates. In nutrient‐limited microhabitats, such as high‐intertidal pools, invertebrate‐excreted ammonium is likely an important local‐scale contributor to macroalgal productivity.

DEVELOPMENT OF ARTIFICIAL TIDE POOL UNITS

The natural coast continues to undergo changes, but structures such as seawalls now serve only one purpose, i. e. protection. In recent years, as ecofriendly structures are desirable, artificial rocky beaches are now projected as places of recreation where people can learn about shorelife. Unfortunately, in many cases, due to the lack of storing water in rocky beaches at low tide, the biota therein shows little diversity. Observation of a natural beach was conducted at Kominato in Chiba. Tide pools provide very valuable, habitats for seaweed and sea creature. They have the important function of not only storing water, but also providing micro-topographes in the pool such as cracks, crevices and pits. Accordingly, new artificial tide pool units have been developed, which fill up with seawater during the ebb tide to ensure suitable micro-topography for shorelife. An example of the design method of such a system is provided.