Adverse Effect of Ocean Acidification on Marine Organisms

Abstract

EditorialEvidence over the past 20 years indicates that marine organisms live in a multistressor environment caused by anthropogenic activities since industrialization and agriculture have generated chemical pollution along with several modifications of the ocean temperature and pH [1].Ocean acidification (OA) is a process induced by a change in the chemistry of carbonate. In normal situations carbon dioxide (CO 2 ) is produced by either photosynthesis and respiration and in long term scale by geological processes, however the excess of CO 2 generated by fuel burning and industries and released in the atmosphere is uptaken and stored in the oceans [2]. Such dissolved CO 2 into the water surface is progressively creating a pH gradient towards more acidic conditions ultimately resulting in a generalized pH decline. pH of coastal marine waters varies of about 0.5 units in physiological conditions, however different conditions as seasonality, circadian cycles and runoff may strongly influence pH oscillations. At present, scientific community is alarming since it has been predicted that mean global pH will decrease of about 0.5 units within 2,100 generating a diffused OA. Furthermore OA will be accompanied by a generalized global warming [3] and changes of other parameters such as salinity and available oxygen. These multistress conditions may seriously threat marine species that live and reproduce along the coasts inducing pronounced deleterious effects on structure and functions of marine ecosystems.Acidification impacts physiological cell processes by influencing the acid-base balance or redox affecting in turn cellular homeostasis which is at the basis of several metabolic, osmotic and ionic pathways.In recent years, many studies have been addressed to evaluate possible impacts of low pH on marine animals [4]. It is known that calcified structures associated with some marine species play a fundamental role in protecting organisms from predators and in improving the access to light and nutrients. Many authors demonstrated a reduced calcification rates in shell/skeletons building of marine organisms from plankton to echinoderms, corals and benthic molluscs submitted to acidified seas conditions. In particular several calcifying species exhibited a reduced calcification and growth rates in laboratory experiments under high-pCO 2 conditions. Other studies, performed in mesocosms and natural waters around volcanic vents areas, did show a clear reduction of calcareous epibionts that in turn impacted the diversity of seagrass species [5]. Conversely, it was observed that sea urchin, corals and mussels are able to survive to a decreased calcification but suffer for a reduced mechanical performance affecting in turn key biotic and abiotic interactions [6]. The structural integrity of components such as shells in bivalve mussels is fundamentals to deter predator's actions as well as is important biomaterials aimed to ensure the attachment of animals to the rocks such as proteinaceous byssal threads that anchor mytilid muss...

Effects of ecosystem stress on reproduction and development

“…Ocean acidification due to the excessive industrial production of CO 2 in the atmosphere is causing a progressive decrease of seawater pH which is estimated to reach 7.8 at the end of this century (Foo, Byrne, Ricevuto, & Gambi, ; Gallo & Tosti, ). This represents a serious matter of concern due to the potential impact of global acidification on population decline and extinctions.…”