Impact of ocean acidification and warming on the feeding behaviour of two gastropod species

Abstract

Increased atmospheric CO2 produced by anthropogenic activities will be absorbed by the oceans over the next century causing ocean acidification and changes in the seawater carbonate chemistry. Elevated CO2 causes sublethal physiological and behavioural responses on the locomotion and foraging behaviour of marine organisms. This study aims to investigate the independent and synergistic effects of long term exposure to low pH and increased temperature on the feeding behaviour of two gastropod species, Hexaplex trunculus and Nassarius nitidus, both in adults and juveniles. Gastropods were maintained under controlled conditions of temperature (ambient = 20°C, increased = 23°C) and pH (ambient = 8, low = 7.6) for 2.5 years. The percentage of animals which successfully reached their food, the response time until gastropods began moving, the total duration until they reached food and the total distance covered, were measured. Speed and path index (i.e how straightforward the movement is) were estimated as means of foraging efficiency. Increased temperature (under ambient pH) resulted in faster responses, a shorter duration until food was reached and a higher speed in H. trunculus adults. H. trunculus (both adults and juveniles) were less successful in reaching their food source under low pH and ambient temperature in comparison to all other treatments. The response time, duration, speed and path index were not affected by low pH (at ambient or increased temperature) for H. trunculus adults and juveniles, as well as for N. nitidus. The foraging performance of juveniles hatched and developed under low pH (either at ambient or increased temperature) was more effective than adults of the same species, thus indicating a degree of acclimation. Also, the scavenger N. nitidus was more successful and responded faster in reaching carrion than the predator H. trunculus, whereas no significant effects were observed for N. nitidus under low pH.

Differential feeding rates of native and alien predators on the invasive Asian date mussel Arcuatula senhousia (Benson in cantor, 1842) in a Mediterranean coastal lagoon

“…Nevertheless, previous studies, although based on different prey species, reported that the attacks by H. trunculus on small specimens of the mussel Brachidontes pharaonic (Fischer, 1870) (5–10 mm shell length) were completed in <4 h (Rilov et al, 2004). Also, Chatzinikolaou et al (2019) proved that ca. 45% of 10 days‐fasted H. trunculus successfully reached the offered food items in <1 h. Considering that the prey individuals used in our experiment had a length <15 mm and the shell of A. senhousia is more fragile than that of other mussels, we contend here that the duration of our experiment (24 h) could have not been an interfering factor.…”

Morphological Properties of Gastropod Shells in a Warmer and More Acidic Future Ocean Using 3D Micro-Computed Tomography

“…Ocean warming and acidification have been proven to affect physiological responses in marine molluscs (e.g., depression of metabolic rate, Bibby et al, 2007; alterations of immune responses and enzyme production, Matozzo et al, 2013), as well as behavioral responses related to predator avoidance (Bibby et al, 2007), reduction of feeding efficiency (Vargas et al, 2013) and movement restriction (Ellis et al, 2009). Hexaplex trunculus was less successful in reaching their food source under low pH (Chatzinikolaou et al, 2019). If such physiological and behavioral restrictions already deteriorate the ability of organisms to successfully cope with predation pressure, a thinner shell will certainly make the situation less favorable.…”

The short and long-term implications of warming and increased sea water pCO2 on the physiological response of a temperate neogastropod species

“…In marine gastropods, few works have assessed the long-term effects of acidi cation and warming. Research has focused on impacts on shell bio-mineralization and morphology (Rühl et al, 2017), feeding physiology and behaviour (Chatzinikolaou et al, 2019;Zhang et al, 2015); however, no study has assessed the combined effects of short-and long-term exposure to climate change in the physiology of marine gastropods.…”