Density-driven water exchange controls seasonal declines in jellyfish (Aurelia aurita) abundance in a shallow fjord system

Abstract Lo, W-T., Purcell, J. E., Hung, J-J., Su, H-M., and Hsu, P-K. 2008. Enhancement of jellyfish (Aurelia aurita) populations by extensive aquaculture rafts in a coastal lagoon in Taiwan. – ICES Journal of Marine Science, 65: 453–461. Blooms of the moon jellyfish, Aurelia aurita, often occur in coastal waters that are heavily affected by human construction, such as harbours. Tapong Bay is a hypertrophic lagoon in southwestern Taiwan that was studied between August 1999 and September 2004. The removal of extensive oyster-culture rafts in June 2002 provided a “natural” experiment to examine the effects of aquaculture on processes and communities in the lagoon. The removal caused many changes in the ecosystem, including increases in flushing, light penetration, dissolved oxygen, salinity, chlorophyll a, primary production, and zooplankton, but decreases in nutrients, periphyton, and dramatically reduced populations of bivalves, zooplanktivorous fish, and jellyfish (A. aurita). We conclude that environmental and trophic conditions were favourable for jellyfish throughout the study period. Therefore, we believe that aquaculture rafts enhanced jellyfish populations by three probable mechanisms: the rafts provided substrate and shading for the larval settlement and polyp colony formation, and the rafts restricted water exchange in the lagoon. Aquaculture is increasing rapidly in Asia, and the problems associated with jellyfish may also increase.

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Modelling the water exchange of a fjord system on the Swedish west coast

10.5194/egusphere-egu21-892 ◽

2021 ◽

Author(s):

Sandra-Esther Brunnabend ◽

Lars Axell ◽

Maximo Garcia-Jove ◽

Lars Arneborg

Keyword(s):

West Coast ◽

Water Exchange ◽

Horizontal Resolution ◽

Swedish West Coast ◽

Fjord System ◽

The North ◽

The North Sea ◽

Model Setup ◽

Sea Area

The water exchange between the Orust-Tj&#246;rn fjord system (located on the Swedish west coast) and the Skagerrak depends on different factors such as winds, tides, the water mass properties and circulation in the Skagerrak, as well as the density gradients between the southern and northern openings of the fjord system. These processes are not yet well understood as observations in the area are spatially and temporally sparse and the existing regional ocean models for the North Sea and Baltic Sea area have a too coarse resolution to sufficiently resolve the complex structures of the fjord system, such as the narrow and shallow channels that connect the different fjords in the system.Therefore, we model the water exchange between the Orust-Tj&#246;rn fjord system and the Skagerrak using a NEMO3.6 model setup that has a horizontal resolution of 50 m. As validation, modelled temperature, salinity, velocity and sea surface height are compared with in-situ measurements. A detailed analysis of the modelled water flows in and out of the fjord system as well as between the different fjords will be presented. In addition, the different drivers of the modelled water exchange and their influence on the water properties above and below the sill depths in the fjords are investigated.

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Drivers of water exchange in the ORUST fjord system

10.5194/egusphere-egu2020-2338 ◽

2020 ◽

Author(s):

Sandra-Esther Brunnabend ◽

Lars Axell ◽

Maximo Garcia-Jove ◽

Lars Arneborg

Keyword(s):

Surface Water ◽

Baltic Sea ◽

Water Exchange ◽

Sea Water ◽

Water Masses ◽

Open Boundary ◽

Small Scale ◽

Open Boundary Conditions ◽

Near Surface ◽

Fjord System

The Orust fjord system, located on the west coast of Sweden, has openings on both ends and consists of several fjords that are connected by narrow and shallow channels. The fjord system includes the islands Orust and Tj&#246;rn as well as various smaller islands. The water exchange between the Kattegat and the different fjords is influenced by different factors, such as winds, tides, and density gradients. However, advection between the open sea and the complex fjord system are not yet well understood as lower resolution ocean models cannot resolve the small scale structures of the fjords and their connections. In addition, observations are rather sparse.Therefore, the water exchange in the Orust fjord system is simulated using a high resolution (50 meter) NEMO3.6 ocean model setup, forced with the UERRA atmospheric reanalysis dataset. The lateral open boundary conditions for temperature, salinity, sea levels and velocities are provided by a low resolution (1.85 km) NEMO3.6 simulation, which spans the Baltic Sea and North Sea regions.The model results are validated by comparison of modelled temperature, salinity, velocities and sea surface height with in-situ measurements. A detailed analysis of the different drivers of modelled water exchange between the Kattegat and the fjord system as well as between the different basins is presented. In general, the modelled water properties of the near surface layer in the fjord system are influenced by the Skagerrak surface water, which is controlled by the prevailing northward flowing Baltic Sea water. However, the residence times of water masses below the sill level are longer than the ones of the surface water masses as dense inflows of Skagerrak water in the basins create a strong stratification leading to weak vertical exchange.

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The main principles and results of pollution monitoring of sediments in the river basin

Melioration and Water Management ◽

10.32962/0235-2524-2019-4-14-20 ◽

2020 ◽

pp. 14-20

Author(s):

B. Korzhenevsky ◽

Gleb Tolkachev ◽

Nikolay Kolomiycev

Keyword(s):

Heavy Metals ◽

River Basin ◽

Water Exchange ◽

Pollution Monitoring ◽

Small Rivers ◽

Volga River ◽

Natural Landscape ◽

Volga River Basin ◽

Ivankovo Reservoir ◽

Selection Of

The problems of modern geological ecology associated with the study of pollution of sediments of water bodies by heavy metals are considered. The Volga River basin is quite heterogeneous, both in geomorphological and hydrological terms, and in thechnogenical development and usage. A fourrank taxonomy is presented for the selection of sites for monitoring, based on a combination of natural, landscape, climatic and thechnogenical factors. To the largest – the highest taxon – sites of the Ist category – bowls of reservoirs with the slopes and the urban zones, industrial and agricultural structures located within them are carried. Within these areas are allocated to smaller taxa, areas category IInd are the industrial and urban zones, areas category IIIrd are the small rivers without significant contamination and areas category IVth to conduct special observations. The examples of special observations in the study of the annual migration of heavy metals in the system «bottom sediments – water column» on the Ivankovo reservoir are highlighted. The investigations were carried out under the conditions of the standard flow rate for this reservoir and in the conditions of slow water exchange.

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Bioenergetic characterization in Aurelia aurita (Cnidaria: Scyphozoa) polyps and application to natural polyp populations

Marine Ecology Progress Series ◽

10.3354/meps12055 ◽

2017 ◽

Vol 568 ◽

pp. 87-100 ◽

Cited By ~ 6

Author(s):

H Ikeda ◽

C Mizota ◽

S Uye

Keyword(s):

Aurelia Aurita

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Carbon Dioxide and Water Exchange Between Spruce and Atmosphere in the Spring-Summer in Different Weather Conditions

Сибирский экологический журнал ◽

10.15372/sej20190105 ◽

2019 ◽

Keyword(s):

Carbon Dioxide ◽

Water Exchange ◽

Weather Conditions

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Water-exchange Processes as Factor of the Energy Fluxes Formation in Ecosystems of the Dnieper Reservoirs

Hydrobiological Journal ◽

10.1615/hydrobj.v46.i5.100 ◽

2010 ◽

Vol 46 (5) ◽

pp. 91-105 ◽

Cited By ~ 2

Author(s):

V. M. Timchenko

Keyword(s):

Water Exchange ◽

Energy Fluxes ◽

Exchange Processes

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SELF-PURIFICATION OF SEA COASTAL WATER AREAS UNDER CLIMATIC AND ANTHROPOGENIC CHANGE

Proceedings of International Conference "Managinag risks to coastal regions and communities in a changinag world" (EMECS'11 - SeaCoasts XXVI) ◽

10.31519/conferencearticle_5b1b949eaa36b5.77769862 ◽

2017 ◽

Author(s):

Irina Mesenzeva ◽

Elena Sovga ◽

Tatyana Khmara ◽

...

Keyword(s):

Anthropogenic Impact ◽

Water Exchange ◽

Water Area ◽

Clean Water ◽

Ecological State ◽

Anthropogenic Change ◽

Run Off ◽

Open Sea ◽

Sevastopol Bay ◽

Assimilation Capacity

The ability of a bay and gulf ecosystems to self-purification was estimated and the current ecological state of the Sevastopol Bay in whole and the separated parts of the bay was given as an example. A zoning by type of anthropogenic impact subject to the water exchange with the open sea and an influence of the Chernaya River run-off were taken into account. A comparative analysis of assimilation capacity of the most environmentally disadvantaged part of the Sevastopol Bay (the Southern Bay) and the clean water area, bordering on the open sea, was carried out. The hydrodynamic regime of the Sevastopol Bay was described using numerical modelling. The prospect, opportunity and examples of the methodology for assessing the assimilation capacity of marine ecosystems are demonstrated.

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