Marmara Denizi’nde Deniz Salyası/Müsilajı Oluşturan Sebepler

2021 ◽  
pp. 85-104
Author(s):  
Ahsen Yüksek
Keyword(s):  
Aurelia Aurita

Jelimsi canlılar veya denizanaları yüksek düzeyde bozulmuş sistemlerin göstergeleri olarak kabul edilmesine rağmen, organik madde ve mikro planktonun filtrasyonundan trofik seviyenin üst segmentlerine kadar önemli rol oynadıklarından, pelajik sistemin anahtar türleridir. Genel olarak ani ve aşırı artışları, ötrafikasyonu, kıyı dolgusu, avcılık gibi yerel ekosistem dengelerinin ani bozulması yanı sıra, iklim değişikliğine bağlı olarak tür dağılımının genişlemesi ve üreme potansiyelinin artışı ile de ilişkilendirilmektedir. Yerli olmayan jelimsi türlerin bozulmuş ekosistemlere kazara girmesi, aşırı çoğalarak ciddi sonuçlara neden olabilir. Bunu 2007’de Liriope tetraphylla türlerinin oluşturduğu ekosistem hasarı ile gördük. Günümüzde pelajik sistemin tekrar çökmesinde ise yerler türler rol oynamıştır. Yerli türlerin aşırı artışlarında rol oynayan ana etken küçük pelajik üzerindeki aşırı avcılık baskısı ve besin bolluğudur. 2018’de kaydedilen aşırı avcılığın ardından, Marmara Denizi’nde önce Salpa kolonileri ardında Rhizostoma pulmo ve Aurelia aurita türlerinde aşırı artışlar, fitoplankton ve zooplankton yoğunluğunda ise belirgin düşüş gözleniyor. Sonuç olarak, plankton üstünden beslenen balık türleri tür çekilince yerini yine plankton üstünde beslenen jelimsi canlılar alıyor. Kasım aralık ayında balıkçıların salya dedikleri oluşum başlıyor ve ardından yoğun nanoplankton çoğalması izleniyor. Böylece Marmara Denizi pelajik sistem besin akışı tamamen değişiyor. Yapılan aylık gözlemlemelerde musilaj oluşumunu tetikleyen sistemin ortamdaki jelimsi canlıların artışı ile kuvvetli ilişkisi vardır.

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

2018 ◽  
Vol 597 ◽  
pp. 137-145 ◽  
Author(s):  
J Goldstein ◽  
C Jürgensen ◽  
UK Steiner ◽  
HU Riisgård
Keyword(s):  
Water Exchange ◽  
Aurelia Aurita ◽  
Fjord System

scholarly journals Shorter, warmer winters may inhibit production of ephyrae in a population of the moon jellyfish Aurelia aurita

Hydrobiologia ◽  
2020 ◽  
Author(s):  
Alexandra Loveridge ◽  
Cathy H. Lucas ◽  
Kylie A. Pitt
Keyword(s):  
Incubation Time ◽  
Life Stage ◽  
Aurelia Aurita ◽  
The Moon ◽  
Minimum Period ◽  
Moon Jellyfish ◽  
Winter Conditions ◽  
Scyphozoan Jellyfish ◽  
Significant Production ◽  
Planula Larvae

AbstractScyphozoan jellyfish blooms display high interannual variability in terms of timing of appearance and size of the bloom. To understand the causes of this variability, the conditions experienced by the polyps prior to the production of ephyrae in the spring were examined. Polyps reared from planula larvae of Aurelia aurita medusae collected from southern England (50°49′58.8; − 1°05′36.9) were incubated under orthogonal combinations of temperature (4, 7, 10 °C) and duration (2, 4, 6, 8 weeks), representing the range of winter conditions in that region, before experiencing an increase to 13 °C. Timing and success of strobilation were recorded. No significant production of ephyrae was observed in any of the 2- and 4-week incubations, or in any 10 °C incubation. Time to first ephyra release decreased with longer winter incubations, and more ephyrae were produced following longer and colder winter simulations. This experiment indicates that A. aurita requires a minimum period of cooler temperatures to strobilate, and contradicts claims that jellyfish populations will be more prevalent in warming oceans, specifically in the context of warmer winter conditions. Such investigations on population-specific ontogeny highlights the need to examine each life stage separately as well as in the context of its environment.

scholarly journals Observations on the ciliary currents of the jelly-fish Aurelia aurita L.

1955 ◽  
Vol 34 (2) ◽  
pp. 201-216 ◽  
Author(s):  
A. J. Southward
Keyword(s):  
Morphological Changes ◽  
Aurelia Aurita ◽  
Gastric Cavity ◽  
Larval Stages ◽  
Blind Ending ◽  
Lateral Tract

SUMMARYThe jelly-fish Aurelia aurita possesses external and internal ciliary currents that play a large part in food collection and in the transport of food, reproductive products and excretory matter.Adults feed on relatively small organisms, which are collected in mucus on all external surfaces and eventually passed to the inner surfaces of the oral arms.The inner surfaces of the oral arms bear two ciliated tracts which operate simultaneously in opposite directions. The lateral tract carries food materials proximally towards the gastric pouches, but is capable of rejecting inedible matter. The basal tract carries excretory matter distally, away from the gastric pouches and canals to the exterior.Rejection reactions are also found in the gastric pouches and radial canals, parts of which have currents moving in opposite directions on the roof and on the floor. These opposing currents appear to be derived from the system in the ephyra stage, where the circulation in the wide gastric cavity and blind-ending canals is maintained partly by centripetal currents on the floor and centrifugal currents on the roof.The directions of the main currents remain constant throughout the larval stages to the adult, although slight variations are introduced by morphological changes. The currents also remain the same during spawning, when the eggs and sperm leave the gastric pouches by the normal excretory path.Many of the ciliary currents found in Aurelia are present in other semaeostome and rhizostome medusae, but only in Aurelia do the umbrella surfaces and currents play a large part in food collection.

scholarly journals VARIATION IN AURELIA AURITA

Biometrika ◽  
1901 ◽  
Vol 1 (1) ◽  
pp. 90-108 ◽  
Author(s):  
E. T. BROWNE
Keyword(s):  
Aurelia Aurita

Memoirs: On the Variation of the Tentaculocysts of Aurelia aurita

1895 ◽  
Vol s2-37 (147) ◽  
pp. 245-251
Author(s):  
EDWARD T. BROWNE
Keyword(s):  
Aurelia Aurita

scholarly journals HUBUNGAN KEPADATAN IKAN DENGAN KONDISI LINGKUNGAN PERAIRAN ESTUARI DI KABUPATEN BANYUASIN

2017 ◽  
Vol 23 (2) ◽  
pp. 111
Author(s):  
Aroef Hukmanan Rais ◽  
Rupawan Rupawan ◽  
Herlan Herlan
Keyword(s):  
Water Temperature ◽  
Significant Contribution ◽  
Aurelia Aurita ◽  
Total Biomass ◽  
Biomass Distribution ◽  
Phytoplankton Abundance ◽  
Biomass Density ◽  
Fish Resources ◽  
Salinity Water ◽  
Distribution Of Fish

Estuari di wilayah Kabupaten Banyuasin dengan potensi biodiversitas sumber daya ikan yang tinggi, merupakan wilayah penangkapan yang potensial dan berkontribusi besar terhadap poduksi perikanan Provinsi Sumatera Selatan. Distribusi biomassa sumber daya ikan di wilayah estuari sangat dinamis dan dipengaruhi oleh parameter salinitas dan suhu perairan pada suatu lingkungan perairan. Penelitian ini bertujuan untuk mengetahui kondisi kepadatan biomassa ikan dalam hubungannya dengan kondisi lingkungan perairan di wilayah perairan estuari Kabupaten Banyuasin.Pengambilan sampel ikan dilakukan dengan percobaan penangkapan menggunakan alat tangkap trawl mini yang diopeasikan di tiga wilayah estuari yaitu Sungai Banyuasin, Sungai Musi dan Sungai Upang. Pada masing-masing wilayah estuari ditentukan sebanyak empat lokasi sampling. Frekuensi pengambilan sampel dilakukan sebanyak empat kali yaitu pada Maret, Juni, Agustus dan Oktober agar mewakili kondisi musiman.Parameter lingkungan yang dianalisa adalah salinitas, suhu perairan, kecerahan, nitrat, amoniak, total fosfat dan kelimpahan fitoplankton. Hasil penelitian menunjukkan sebanyak 87 spesies ikan telah teridentifikasi. Diperoleh nilai kepadatan biomassa 332,13 – 861,49 kg/km2 di estuari Upang, 590,51 – 2.235,04 kg/km2 di estuari Musi dan 1.296,4 - 33.714,88 kg/km2 di estuari Banyuasin. Spesies ubur-ubur (Aurelia aurita) mendominasi tangkapan pada Agustus hingga Oktober yang mencapai 77,22% dari biomassa total ikan dikarenakan lingkungan yang sesuai untuk keperluan pertumbuhannya. Kepadatan biomassa ikan berkorelasi positif dengan parameter salinitas dan kelimpahan fitoplankton, dan berkorelasi negatif terhadap parameter amoniak. Estuaries of Banyuasin district has a high biodiversity of fish resources and significant contribution to the fisheries production in the South Sumatera Province. The biomass distribution of fish in the estuary fluctuated and probably affected by by salinity and water temperature. This research aims to investigate the correlation between biomass density and environment condition in the estuary of Banyuasin Regency. Sampling was conducted through experimental fishing used a mini trawl that operated in three estuary areas, such as: Banyuasin Rivers, Musi Rivers, and Upang Rivers. Every estuary area was replicated for four sampling sites. Samples were collected during March, June, August and October. The waters parameters analyzed were salinity, water temperature, transparency, nitrate, ammonia, phosphate total, and phytoplankton. The results showed that about 87 species of fish have been identified. The biomass density was 332,13 – 861,49 kg/km2 in estuary Upang, 590,51 – 2.235,04 kg/km2 in estuary Musi and 1.296,4 - 33.714,88 kg/km2 in estuari Banyuasin. A jelly fish (Aurelia aurita) is dominated in August to October, up to 77.22% of total biomass. The biomass density of fish was positively correlated with salinity and phytoplankton abundance, whereas negatively correlated to ammoniac condition.

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