Metabolic activity of the bivalves Noah's ark, Arca noae Linnaeus, 1758 and bearded horse Mussel, Modiolus barbatus (Linnaeus, 1758)

Metabolizam je skup kemijskih reakcija u organizmu koje omogućuju izgradnju i razgradnju tvari, dobivanje energije i rast i njegovo poznavanje daje vrijedne informacije o istraženim vrstama. Temeljni cilj ovog rada je istražiti fiziološki odgovor kunjke Arca noae i bijele dagnje Modiolus barbatus na različite vrijednosti saliniteta, količine hrane i veličinu jedinka. Istraživana je potrošnja kisika, izlučivanje amonijaka, atomski odnos kisika i dušika (O:N) i stopa pročišćavanja. Iako su ove vrste često istraživane, vrlo je malo podataka objavljeno o njihovim fiziološkim odgovorima na stres. Istraživanje je provedeno u Malostonskom zaljevu u razdoblju od travnja 2014. do lipnja 2016. godine. Zabilježena je statistički značajna razlika u potrošnji kisika kunjke u odnosu na različite vrijednosti saliniteta i na različite veličine jedinka. U potrošnji kisika bijele dagnje opažena je statistički značajna razlika u odnosu na vrijeme hranjenja i na različite veličine jedinka. Statistički značajna razlika u izlučivanju amonijaka kod kunjke zabilježena je u odnosu na različite vrijednosti saliniteta, promjenu količine hrane, vrijeme hranjenja i veličine jedinki. Kod bijele dagnje različite vrijednosti saliniteta ne utječu značajno na izlučivanje amonijaka, a statistički značajna razlika javlja se u odnosu na vrijeme izlaganja salinitetu, promjenu količine hrane i vrijeme hranjenja. Različite veličine pokusnih jedinka, promjena količine hrane i vrijeme hranjenja statistički značajno utječu na O:N odnos kunjke i bijele dagnje. Razlike u stopi pročišćavanja kod obje vrste zabilježene su u odnosu na salinitet, vrijeme hranjenja i veličinu jedinka. Vrijeme izlaganja različitom salinitetu ima veći utjecaj kod kunjke. Rezultati pokazuju fiziološki odgovor školjkaša na promijenjene uvjete u kojima bijela dagnja nešto bolje reagira na stres. Sezonska istraživanja bi mogla detaljnije opisati dugotrajniji odnos između ovih vrsta i okoliša.Metabolism is a set of chemical reactions in an organism that provide energy and enable growth and knowledge about its function provides valuable information on the species researched. The aim of this paper was to investigate the physiological response of Noah's ark, Arca noae and bearded horse mussel, Modiolus barbatus to different salinity values, the amount of food and the size of the individual. The oxygen consumption, ammonia excretion, atomic oxygen and nitrogen ratio (O: N) and clearance rate were investigated. Although these species are often explored, very little information has been published about their physiological responses to stress. The study was conducted in the Mali Ston Bay in the period from April 2014 to June 2016. There was a statistically significant difference in the consumption of oxygen of Noah' Ark shell due to different salinity values of seawater and considering the different sizes of test organisms. In the oxygen consumption of bearded horse mussel, a statistically significant difference was observed with respect to feeding time and to different sizes of individuals. There was a statistically significant difference in the excretion of the ammonia of Noah' Ark shell due to the different values of seawater salinity, given the different amount of food, time of feeding and the different size of the individual. In bearded horse mussel different values of seawater salinity do not significantly affect the excretion of ammonia, a statistically significant difference occurs with respect to exposure time to salinity, different amount of food and feeding time. Different sizes of experimental animals, change of food quantity and feeding time statistically significantly affect the O:N ratio of bearded horse mussel and Noah' Ark shell. Differences in the clearance rate in both species were recorded in terms of salinity, feeding time and the size of the individual. Exposure time to different salinity has a greater impact on the Noah' Ark shell. The results show the physiological response of bivalve molluscs to changed conditions where the bearded horse mussels respond better to stress. Seasonal research could provide a more detailed description of the longer-lasting relationship between these species and the environment