scholarly journals THE PHYSICAL ENVIRONMENT IN CORAL REEFS OF THE TAYRONA NATIONAL NATURAL PARK (COLOMBIAN CARIBBEAN) IN RESPONSE TO SEASONAL UPWELLING

2016 ◽  
Vol 43 (1) ◽  
Author(s):  
Elisa Bayraktarov ◽  
Martha L Bastidas Salamanca ◽  
Christian Wild
Keyword(s):  
Coral Reef ◽  
Coral Reefs ◽  
Current Velocity ◽  
Physical Environment ◽  
Water Current ◽  
Exposed Site ◽  
Water Currents ◽  
Natural Park ◽  
Water Current Velocity ◽  
Sheltered Site

Coral reefs are subjected to physical changes in their surroundings including wind velocity, water temperature, and water currents that can affect ecological processes on different spatial and temporal scales. However, the dynamics of these physical variables in coral reef ecosystems are poorly understood. In this context, Tayrona National Natural Park (TNNP) in the Colombian Caribbean is an ideal study location because it contains coral reefs and is exposed to seasonal upwelling that strongly changes all key physical factors mentioned above. This study therefore investigated wind velocity and water temperature over two years, as well as water current velocity and direction for representative months of each season at a windand wave-exposed and a sheltered coral reef site in one exemplary bay of TNNP using meteorological data, temperature loggers, and an Acoustic Doppler Current Profiler (ADCP) in order to describe the spatiotemporal variations of the physical environment. Findings revealed that water temperatures (28.7 ± 0.8 °C and maximal 30.3 °C during non-upwelling; 25.1 ± 1.7 °C and minimal 20.3 °C during upwelling) exhibited no significant differences between sites and were negatively correlated with wind velocities (0.4 ± 0.3 m s-1 during non-upwelling and 1.8 ± 1.0 m s-1 with a maximum of 4.1 m s-1 during upwelling). Water current velocity was significantly higher at the exposed compared to the sheltered site during non-upwelling periods at a water depth of 8-10 m. During upwelling, water current velocities were also higher at the exposed site (6.4 cm s-1 exposed and 5.9 cm s-1 sheltered), but when wind speed surpassed 1.7 m s-1, no spatial differences occurred. Water currents showed a clockwise circulation during upwelling following the wind fields, but no clear circulation pattern during non-upwelling. Significant positive correlation between wind and water current velocity was detected at the sheltered, but not at the exposed site. Wind-stress at the exposed site affected water currents throughout the entire water column (at least 10 m deep) during both seasons, but reached only until 3-4 m water depth at the sheltered site during non-upwelling and down to 10 m during upwelling. Consequently, organisms at the exposed site experience constantly high water current exposure throughout the year. This may explain the pronounced site-specific reef community composition differences as water current velocity and circulation control distribution of invertebrate larvae and supply with plankton and essential nutrients.

scholarly journals Spatiotemporal variability of sedimentary organic matter supply and recycling processes in coral reefs of Tayrona National Natural Park, Colombian Caribbean

2014 ◽  
Vol 11 (11) ◽  
pp. 2977-2990 ◽  
Author(s):  
E. Bayraktarov ◽  
C. Wild
Keyword(s):  
Organic Matter ◽  
Coral Reef ◽  
Coastal Upwelling ◽  
Sediment Traps ◽  
Sedimentary Organic Matter ◽  
Spatiotemporal Variability ◽  
Water Current ◽  
Labile Organic Matter ◽  
Natural Park ◽  
River Mouths

Abstract. Sediments are fundamental for the function of oligotrophic coral reef ecosystems because they are major places for organic matter recycling. The Tayrona National Natural Park (TNNP, Colombian Caribbean) is located between the population center Santa Marta (>455 000 inhabitants) in the southwest and several river mouths in the east. Here, coral reef sediments experience pronounced changes in environmental conditions due to seasonal coastal upwelling, but knowledge of relevant spatiotemporal effects on organic matter supply to the sediments and recycling processes is not available. Therefore, sediment traps were deployed monthly over 14 months complemented by assessment of sedimentary properties (e.g., porosity, grain size, content of particulate organic matter and pigments) and sedimentary O2 demand (SOD) at water-current-exposed and sheltered sites along distance gradients (12–20 km) to Santa Marta and the eastern river mouths (17–27 km). Findings revealed that seasonal upwelling delivered strong (75–79% of annual supply) pulses of labile organic matter mainly composed of fresh phytoplankton detritus (C : N ratio 6–8) to the seafloor. Sedimentary chlorophyll a contents and SOD increased significantly with decreasing distance to the eastern rivers, but only during upwelling. This suggests sedimentary organic matter supply controlled by nutrient-enriched upwelling waters and riverine runoff rather than by the countercurrent-located city of Santa Marta. Organic matter pulses led to significantly higher SOD (more than 30%) at the water-current-sheltered sites as compared to the exposed sites, ensuing a rapid recycling of the supplied labile organic matter in the permeable silicate reef sands.

scholarly journals KESESUAIAN LAHAN PANTAI UNTUK WISATA DAN BERENANG DI KABUPATEN LOMBOK TIMUR

2018 ◽  
Author(s):  
Indra Agus Riyanto ◽  
Muh Aris Marfai ◽  
Ahmad Cahyadi
Keyword(s):  
Current Velocity ◽  
Initial Study ◽  
Land Suitability ◽  
Water Current ◽  
The North ◽  
Water Current Velocity ◽  
Beach Width ◽  
Preliminary Study ◽  
Coastal Land ◽  
Water Bottom

East Lombok Regency has different beach variations from the north, middle, and south in terms of its constituentmaterial. The beauty of the beach in East Lombok District has not been well managed and developed so that it is lessdeveloped than the other beaches in Lombok Regency. Therefore, a preliminary study is needed in the developmentof coastal tourism in East Lombok Regency. The initial study that needs to be done is the land suitability of coastalfor tourism and swimming in East Lombok Regency. Parameters used for land suitabiliy coastal for swimmingconsist of 10 parameters, coastal typology, beach width, depth of water, bottom of water, current velocity, beachslope, water brightness, land cover, hazardous biota, the depth material of the waters, and availability of fresh water.Parameters for land suitability of coastal for tourism consisting of 8 parameters, the depth of the waters, the type ofbeach, the width of the beach, the depth material of the waters, current velocity, brightness of the waters, dangerousbiota and availability of freshwater. The land suitability class is divided into four classifications, namely highlysuitable (S1), moderately suitable (S2), marginally suitable (S3), and not suitable (N). The beaches studied areLabuan Haji, Pink, Gili Kondo, Gili Petagan, Gili Kapal, Surga, Rambang, Lampu, and Gili Bidara. The results of thestudy of coastal land suitability for tourism and swimming are expected to be the basis for the development ofcoastal tourism in East Lombok Regency. The results of land suitability for tourism in Labuan Haji Beach areincluded in S1, Rambang Beach S2, Pink Beach S1, Lampu Beach S1, Surga Beach S2, Gili Petagan S2, Gili Bidara S1,Gili Kapal S2, and Gili Kondo S1. The land suitability for swimming in Labuan Haji Beach includes S1, Rambang BeachN, Pink Beach S1, Lampu Beach S1, Surga Beach N, Gili Petagan S2, Gili Bidara S1, Gili Kapal S2, and Gili Kondo S1.

scholarly journals Condition of Coral Reefs and Reef Fishes in Dofa Village, Sula Islands Regency

2021 ◽  
Vol 5 (1) ◽  
pp. 431-436
Author(s):  
Alimuddin Alimuddin ◽  
Nurul Chayati ◽  
Tedy Murtejo ◽  
La Ode M. Gunawan Giu ◽  
Ria Fitri
Keyword(s):  
Coral Reef ◽  
Coral Reefs ◽  
Current Velocity ◽  
Reef Fishes ◽  
Fish Diversity ◽  
Live Coral ◽  
Coral Reef Ecosystem ◽  
Coral Fish ◽  
Index Value ◽  
Reef Ecosystem

Coral reefs are unique among ocean associations or communities that are entirely formed by biological activity. This study aims to determine the condition of coral reefs and reef fishes in Dofa Village, West Mangoli District, Sula Islands, 2018. Collecting coral data used the Line Intercept Transect (LIT) method, while coral fish data collection used the visual census method. Water parameters measured are temperature, salinity, degree of acidity (pH), brightness and current velocity. Based on observations, the water temperature ranges from 29.33° C - 29.9° C. The salinity of the waters ranges from 29.67 ‰ - 34 ‰. The degree of acidity is 7.5 which supports the life of coral reef. The water brightness level is 65% - 100%. The current velocity ranges from 0.02 m / s to 0.05 m / s. The condition of the coral reef ecosystem based on the percentage of hard coral cover ranged from 21.02% - 33.7% with low to medium category. The coral mortality index at the study location was small where at station 1 it was 0.487, station 2 was 0.335 and station 3 was 0.205, meaning that there was no significant change for live coral reefs. The abundance of reef fishes ranged from 0.52 ind/m2 - 1.22 ind/m2 which was dominated by the Pomacentridae and Labridae families where the two families were groups of fish that used coral reefs as habitat for feeding ground. The index value of coral fish diversity in the coral reef ecosystem at all stations ranged from 0.58 to 3.60 where the diversity index value was in the low to medium category. The uniformity index is included in the medium category with values ​​ranging from 0.58 to 0.63 which illustrates that the difference in the number of individuals for each species is not too significant. The dominance index of reef fishes at the observation station is very small, ranging from 0.03 - 0.07 which indicates that the dominance of the species is very low, so that the condition of the reef fish community is relatively stable.

Tank Model Testing on the Fish Cage Installed in Variable Depths in Current and Waves

2013 ◽  
Author(s):  
Daisuke Kitazawa ◽  
Hiroki Shimizu ◽  
Yoichi Mizukami
Keyword(s):  
Experimental Data ◽  
Numerical Model ◽  
Current Velocity ◽  
Angle Of Attack ◽  
Hydrodynamic Forces ◽  
Water Current ◽  
Mooring System ◽  
Water Tank ◽  
Tank Model ◽  
Water Current Velocity

A fish cage should be submerged to reduce hydrodynamic forces from high waves if the fish cage is installed in an exposed sea area. Usually, the submergible fish cage is suspended from the framework at a fixed depth. The framework is set by floats and anchors at the middle position between water surface and the top surface of the submergible fish cage. The submergible fish cage will be used not only for reduction of hydrodynamic forces but for the other purposes such as choosing the best environment for cultured fishes in the vertical direction, and escaping from the flood with high-level nitrogen or turbidity, harmful algal blooming, and floating ices. In such cases, it is useful for the fish cage to be installed in variable depths. The purpose of the present study is to examine the safety of the fish cage installed in variable depths in current and waves by means of tank model testing. The mooring system consists of a fish cage and four floats. The vertical position of the fish cage is variable by adjusting the buoyancy of these floats. First, the drag of the fish cage was examined by towing test, and the results were compared with the drag estimated by the existing studies. The effects of interaction among twines, the angle of attack, wake, and the top and bottom nets were discussed. Then the fish cage was moored in the water tank, which has the length of 50 m and the width of 10 m. The tank model has a scale of 1/100 of the full-scale model of the fish cage used for tuna farming. The model was made according to Tauti’s similarity law. The water depth was set at 0.68 m by adjusting the position of the variable floor. The motion of the fish cage and four floats, and the tension of the mooring lines between the fish cage, floats, and anchors were measured by the underwater video camera and load cells, respectively. As a result, the drag of the fish cage could be estimated from the experimental results of the drag of a plane net since the results include the effect of interaction among twines. The effects of the angle of attack and the reduction in water current velocity inside the cage were also taken into account. The drag of the fish cage could be estimated well by the above method, while it was underestimated by 10% in comparison with the experimental data. In the water tank testing of the mooring system, the tension of the mooring line increased rapidly with the increase in water current velocity since the drag of the fish cage was proportional to the 1.8th power of water current velocity and increased due to the inclination of the fish cage. The increase in the tension due to wave-induced forces to the fish cage could be negligible when the fish cage was submerged. The safety and the design guideline of the mooring system should be assessed by the simulations using a numerical model, which is being developed by the authors. The experimental data obtained in the present study will be useful for the validation of the numerical model.

CO2 uptake patterns depend on water current velocity and shoot morphology in submerged stream macrophytes

2006 ◽  
Vol 51 (7) ◽  
pp. 1331-1340 ◽  
Author(s):  
HANNE DALSGAARD NIELSEN ◽  
SOREN LAURENTIUS NIELSEN ◽  
TOM VINDBAEK MADSEN
Keyword(s):  
Current Velocity ◽  
Water Current ◽  
Co2 Uptake ◽  
Shoot Morphology ◽  
Water Current Velocity

Adjustment of Buoyancy in Young Atlantic Salmon and Brook Trout by Changes in Swimbladder Volume

1965 ◽  
Vol 22 (2) ◽  
pp. 335-352 ◽  
Author(s):  
Richard L. Saunders
Keyword(s):  
Hydrostatic Pressure ◽  
Atlantic Salmon ◽  
Current Velocity ◽  
Brook Trout ◽  
Water Current ◽  
Flowing Water ◽  
Stages Of Development ◽  
Neutral Buoyancy ◽  
Water Currents ◽  
Salmon Parr

The adjustment of swimbladder volume and the consequent effects on buoyancy in young Atlantic salmon and brook trout at various stages of development were measured in relation to current velocity. This was done by measuring pressure of neutral buoyancy — the pressure at which an anesthetized fish just reached neutral buoyancy as the total (atmospheric plus hydrostatic) pressure was gradually reduced — or by measuring flotation pressure — the ratio of volume of gas in the swimbladder to weight of the gas-free fish in water. Whether in static or flowing water, salmon parr were less buoyant than brook trout. Individuals of both species were more buoyant when held in still water than when held in rapidly flowing water. Adjustment in buoyancy took place when these fishes were subjected to a change in water current. Buoyancy was reduced if they were moved from still water to rapidly flowing water and was increased if they were moved from flowing to still water. Salmon smolts were more buoyant than salmon parr. This greater buoyancy of smolts is not owing to their being larger than parr. Initial filling of the swimbladder in salmon alevins can be delayed by subjecting them to strong water currents.

scholarly journals A STUDY OF CHANNEL WATER CURRENT VELOCITY METER WITH HORIZONTAL AND VERTICAL AXIS PROPELLER TYPE

2015 ◽  
Vol 17 (1) ◽  
Author(s):  
Rahmat Permana ◽  
Bambang Agus Kironoto ◽  
Istiarto .
Keyword(s):  
Current Velocity ◽  
Vertical Axis ◽  
Water Current ◽  
Channel Water ◽  
Water Current Velocity

Current meter adalah salah satu alat ukur kecepatan air. Pada umumnya current meter yang ada di pasaran dibuat oleh pabrik-pabrik di luar negeri dan dalam negeri. Pada rancang bangun ini dibuat alat ukur kecepatan air di saluran dengan tipe propeller poros horisontal dan vertikal terbuat dari bahan resin yang diperkuat dengan bahan fiberglass, sensor putaran menggunakan read switch, pencatat putaran (counter) menggunakan panel meter dengan 7 segmen yang menampilkan 4 angka dan dilengkapi dengan pewaktu yaitu berupa timer switch dengan durasi maksimum 5 menit. Berdasarkan hasil yang didapat dengan penerapan berbagai bahan dan modul yang digunakan  dalam rancang bangun ini dapat terintegrasi dengan baik. Current meter tipe propeller poros horisontal dapat beroperasi pada kisaran kecepatan 0,040 – 2,500 m/s dan tipe propeller poros vertikal dapat beroperasi pada kisaran kecepatan 0,100 – 1,250 m/s.

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