VPLIV PODVODNEGA HRUPA NA MORSKE ORGANIZME

Haložan, Lavra Barbara (author), Bajt, Oliver (mentor)

Onesnaževanje s hrupom se je šele pred kratkim začelo smatrati kot resnična težava, saj so zakonodaje o njegovem zmanjševanju v veljavo prišle komaj nekaj deset let nazaj. Kljub temu pa hrup predstavlja veliko grožnjo predvsem pod vodo, kjer se večina morskih organizmov zanaša na sluh. Zvok se pod vodo širi kot mehansko valovanje, ki se prenaša skozi vodni medij in ker se v vodi bolje ohranja kot v zraku, ima večjo sposobnost potovanja na večjih razdaljah brez izrazitega slabljenja. Splošno rečemo, da je hitrost zvoka v morski vodi približno 1500 m/s, vendar je hitrost odvisna od temperature, slanosti in tlaka v vodi. Z večjo globino je povezano nižanje temperature ter višanje slanosti in tlaka, hitrost zvoka pa je s tem tesno povezana, saj se zvišuje ob višanju teh lastnosti in pada ob nižanju. Vendar pa temperatura pada le do neke točke, ko ostane konstantna, in na tej točki ima hitrost zvoka najnižjo vrednost. Temu rečemo SOFAR kanal, po katerem se zaradi refrakcije zvok lahko širi skoraj na drugo stran sveta. Hrup negativno vpliva tako na morske sesalce kot tudi na deseteronožce, mehkužce, ribe, glavonožce, iglokožce in ostalo, saj ima vsaka od teh vrst sluh razvit za komunikacijo s svojo vrsto in zaznavanje plenilcev, ne pa tudi za kontinuiran zvok, ki ga povzroča ladijski promet, in impulzni zvok, ki ga povzročajo ljudje z eksplozijami, zabijanjem pilotov in ostalimi podvodnimi deli. Takšen hrup lahko pusti dolgotrajne posledice, kot je izguba sluha pri sesalcih, začasna izguba služnih dlačic pri ribah in podobno. V Sloveniji so se meritve podvodnega hrupa začele leta 2015 s strani Inštituta za vode Republike Slovenije, ko se je Slovenija priključila projektu QuietMed, programu, ki se zavzema za izboljšanje stanja morskega okolja na področju hrupa v celotnem Sredozemskem morju. Iz delnih podatkov za leti 2019 in 2020 so bili izvzeti urni podatki, ki prikazujejo, koliko se je količina hrupa v slovenskem morju spremenila v enem letu. Hrup je bil merjen na več različnih frekvencah, v nalogi pa so bili analizirani le podatki za dve frekvenci, in sicer 63 Hz in 125 Hz, saj nizkofrekvenčni zvok potuje dlje, glavni vir hrupa na teh dveh frekvencah pa je ravno ladijski promet. Podatki so bili nato upodobljeni na grafu in potrjujejo, da je količina hrupa, kljub globalni epidemiji, ki je omejila ladijski promet, še vedno naraščala.

• Language: Slovenian
• Keywords: podvodni hrup, morski organizmi, onesnaževanje, zvok, morje
• Work type: Master's thesis/paper
• Organization: FPP - Faculty of Maritime Studies and Transport
• Year: 2023
• PID: 20.500.12556/RUL-151760
• Publication date in RUL: 19.10.2023

Secondary language

• Language: English
• Title: UNDERWATER NOISE IMPACT ON MARINE LIFE

Abstract

Noise pollution has only recently started to be seen as a real problem, with legislation to reduce it only coming into force a few decades ago. However, noise is a major threat, especially underwater, where most marine organisms rely on hearing. Underwater, sound propagates as mechanical waves that are transmitted through the medium of water and, because it is better preserved in water than in air, it has a greater ability to travel over greater distances without significant attenuation. The speed of sound in seawater is generally said to be about 1500 m/s, but the speed depends on the temperature, salinity and pressure of the water. As depth increases, temperature decreases and salinity and pressure increase, and the speed of sound is closely related, increasing as these properties increase and decreasing as they decrease. However, the temperature only decreases up to a point where it remains constant, at which point the speed of sound has its lowest value. This is called the SOFAR channel, through which sound can propagate almost to the other side of the world due to refraction. Noise has a negative impact on marine mammals as well as on decapods, molluscs, fish, cephalopods, echinoderms and others, since each of these species has hearing developed to communicate with its own kind and to detect predators, but not for the continuous sound caused by shipping and the impulsive sound caused by humans with explosions, pile driving and other underwater work. Such noise can have long-lasting effects, including hearing loss in mammals, temporary loss of hearing hairs in fish, and so on. In Slovenia, underwater noise measurements started in 2015 by the Slovenian Water Institute, when Slovenia joined the QuietMed project, a program that aims to improve the marine noise environment throughout the Mediterranean Sea. The partial data for 2019 and 2020 exclude hourly data that show how much the amount of noise in the Slovenian sea has changed in one year. Noise was measured at several different frequencies, but only data for two frequencies, 63 Hz and 125 Hz, were analyzed in this thesis, as low-frequency sound travels further and the main source of noise at these two frequencies is shipping. The data was then plotted on a graph and averaged to calculate the noise levels for each frequency in 2019 and 2020. Comparing the averages confirms that, despite the global epidemic that has restricted shipping, the amount of noise is still increasing.

• Keywords: underwater noise, marine organisms, pollution, sound, sea