The increased absorption of atmospheric CO2 by the ocean reduces pH and affects the carbonate chemistry of seawater, thus interfering with the shell formation processes of marine calcifiers. The present study aims to examine the effects of ocean acidification and warming on the shell morphological properties of two intertidal gastropod species, Nassarius nitidus and Columbella rustica. The experimental treatments lasted for 3 months and combined a temperature increase of 3°C and a pH reduction of 0.3 units. The selected treatments reflected the high emissions (RCP 8.5) “business as usual” scenario of the Intergovernmental Panel on Climate Change models for eastern Mediterranean. The morphological and architectural properties of the shell, such as density, thickness and porosity were examined using 3D micro-computed tomography, which is a technique giving the advantage of calculating values for the total shell (not only at specific points) and at the same time leaving the shells intact. Nassarius nitidus had a lower shell density and thickness and a higher porosity when the pH was reduced at ambient temperature, but the combination of reduced pH and increased temperature did not have a noticeable effect in comparison to the control. The shell of Columbella rustica was less dense, thinner and more porous under acidic and warm conditions, but when the temperature was increased under ambient pH the shells were thicker and denser than the control. Under low pH and ambient temperature, shells showed no differences compared to the control. The vulnerability of calcareous shells to ocean acidification and warming appears to be variable among species. Plasticity of shell building organisms as an acclimation action toward a continuously changing marine environment needs to be further investigated focusing on species or shell region specific adaptation mechanisms.
Feeding rates, growth rates and feed e⁄ciency ratios were studied in experimentally reared juvenile cuttle-¢sh Sepia o⁄cinalis which had been hatched from eggs collected from three di¡erent locations, Plymouth, North Wales and Southampton. Groups of newly hatched cuttle¢sh were either maintained at 19 1C and well fed (experiment 1) or were maintained at ambient seawater temperature (7^16 1C) with little food for 6 months so that their development was delayed and then transferred to optimum conditions (experiment 2). In the ¢rst investigation (expt 1), no signi¢cant di¡erences in growth rates (3.72 AE 0.08%, 3.75 AE 0.04% and 3.55 AE 0.04% body weight (BW) day À1 respectively), feeding rates (9.53 AE 0.36%, 9.28 AE 0.36% and 8.95 AE 0.37% BWday À1 respectively) and feed e⁄ciency ratios (38.11 AE 1.67%, 40.52 AE 1.78% and 39.96 AE 1.78% respectively) were observed between cuttle¢sh from the 3 locations. During the second investigation (expt 2), cuttle¢sh, whose development was initially delayed after hatching and then were stimulated to grow under optimum conditions (19 1C and fed), showed growth rates (3.46 AE 0.08% BWday À1 ) similar to those held under optimum conditions of seawater temperature (19 1C) and food supply shortly after hatching. Feeding rates and feed e⁄ciency ratios were however signi¢cantly higher in cuttle¢sh maintained at 19 1C compared to 11 1C (8.27 AE 0.14% BWday À1 , 41.25 AE 0.52% and 2.75 AE 0.09% BWday À1 , 24.87 AE 1.87% respectively).
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.
This chapter reviews the mechanical (physical) and chemical (water quality) related pathologies that have been reported since cephalopods are maintained, reared or cultured in captivity. For the first time, it builds up on the existing knowledge from researchers and aquarists (which are represented as authors of the chapter) in order to provide the most updated and inclusive revision on this theme. It is organized in terms of pathologies that are reported and eventual described for one or more species, which are commonly kept for research and display purposes, and exemplified with photos when possible. It includes pathologies of the mantle, arms, eyes, shell; egg infections, malformations of the shell and eggs; and causes of disease or mortality related with water quality focusing on pH and trace elements.
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