Utjecaj povišene temperature mora na tkivo koralja

undergraduate thesis

• Title (english): Effects of Rising Sea Temperatures on Coral Tissue
• Author: Miha Jurić
• Mentor: Romana Gračan (mentor)
• Granter: University of Zagreb; Faculty of Science; (Department of Biology); Zagreb
• Defense date and country: 2023-09-20, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Biology

Abstract

Koralji su evolucijski primitivne životinje koje posjeduju samo dva prava tkiva: vanjsko pokrovno
tkivo, epidermu, te unutrašnje tkivo s ulogom probave, gastrodermu. Unutar stanica gastroderme
nalaze se fotosintetski aktivne simbiotske alge. Simbioza se zasniva na izmjeni nutrijenata između
domaćina i simbionta. Globalni trend povišenja temperature mora uzrokuje disfunkciju ove
simbioze te tako ugrožava brojne koralje koji o njoj ovise. Prilikom temperaturnog stresa
gastrodermalno tkivo prolazi „izbjeljivanje“ gdje zbog gubitka alga koralji poprimaju blijedi
izgled. Nakon izbjeljivanja koralji najčešće odumiru zbog nedostatka nutrijenata. Mehanizam
izbjeljivanja na razini stanica još uvijek nije u potpunosti razjašnjen. Kao molekularni okidači
izbjeljivanja često se navode reaktivni kisikovi spojevi, dušikov monoksid ili pak poremećaji u
protoku nutrijenata. Oni će potaknuti izbacivanje simbionata iz koralja koje se može dogoditi na
nekoliko načina: in situ degradacija simbionta, egzocitoza simbionta iz stanice domaćina, apoptoza
stanice domaćina, nekroza stanice domaćina, autofagija stanice domaćina i odvajanje stanice
domaćina od ostatka tkiva. Svojim pojedinačnim ili zajedničkim djelovanjem ovi mehanizmi
dovode do izbjeljivanja tkiva koralja. Modeli koji predviđaju kretanje temperatura mora u
budućnosti ukazuju na nastavak zagrijavanja, pa tako i na veću smrtnost koralja. Stoga iako koralji
pokazuju postepene prilagodbe na zatopljenje mora, nije sigurno hoće li one biti dovoljne za
njihovo preživljavanje.

Abstract (english)

Corals are primitive animals with only two sets of tissues: an outer covering tissue, the epidermis,
and an inner tissue with a role in digestion, the gastrodermis. Within gastrodermal cells are
photosynthetically active symbiont algae. The symbiosis is based on nutrient exchange between
host and symbiont. Global trends of rising sea temperatures cause a dysfunction of this symbiosis
and, therefore, endanger the vast number of corals that rely on it. During thermal stress,
gastrodermal tissue undergoes "bleaching" where a loss of algae gives the coral a pale appearance.
As a result of bleaching, corals often die from lack of nutrients. The mechanisms of bleaching are
still not entirely clear on a cellular level. Reactive oxygen species, NO and disturbances in nutrient
flow are often described as triggers of bleaching. They induce symbiont expulsion which may occur
in several ways: in situ degradation of the symbiont, exocytosis of the symbiont, apoptosis of the
host cell, necrosis of the host cell, autophagy of the host cell and detachment of the host cell. These
mechanisms can work together or separately to accomplish tissue bleaching. Future sea
temperature models suggest continuous warming and, consequently, higher coral mortality.
Although corals are progressively adapting to rising temperatures, it is unsure whether it will be
enough for their survival.

• Keywords: izbjeljivanje koralja; koraljni grebeni; globalno zatopljenje; simbioza
• Keywords (english): coral bleaching; coral reefs; global warming; symbiosis
• Language: croatian
• URN:NBN: urn:nbn:hr:217:165004
• Study programme: Title: Environmental Sciences; Study programme type: university; Study level: undergraduate; Academic / professional title: sveučilišni/a prvostupnik/prvostupnica (baccalaureus/baccalaurea) struke znanosti o okolišu (sveučilišni/a prvostupnik/prvostupnica (baccalaureus/baccalaurea) struke znanosti o okolišu)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2023-09-25 09:28:18