The Mediterranean mussel Mytilus galloprovincialis: responses to climate change scenarios as a function of the original habitat

Abstract

The impact of simulated seawater acidification and warming conditions on specimens of the mussel Mytilus galloprovincialis locally adapted to very distinct, widely separated sites in the Mediterranean Sea (Tunisia) and Atlantic Sea (Galicia, NW Spain) was evaluated in relation to key behavioural and eco-physiological parameters. Over the 2-month exposure to the experimental conditions, mussels were fed optimally to ensure that there are no synergistic interactions between climate change drivers and energetic status of the individuals. In general, regardless of origin (Atlantic or Mediterranean), the mussels were rather resilient to acidification for most of the parameters considered and they were able to grow in strongly acidified seawater through an increased feeding activity. However, shell strength decreased (40%) consistently in both mussel populations held in moderately and highly acidified seawater. The observed reduction in shell strength was not explained by slight alterations in organic matter, shell thickness or aragonite:calcite ratio. The combined effects of high acidification and warming on the key response of byssus strength caused a strong decline in mussel performance, although only in Galician mussels, in which the valve opening time decreased sharply as well as condition index (soft tissue state) and shell growth. By contrast, the observed negative effect of highly acidified scenario on the strength of Tunisian mussel shells was (partly but not totally) counterbalanced by the higher seawater temperature. Eco-physiological and behavioural interactions in mussels in relation to climate change are complex, and future scenarios for the ecology of the species and also the feasibility of cultivating them in Atlantic and Mediterranean zones are discussed.

Trace metal accumulation in the commercial mussel M. galloprovincialis under future climate change scenarios

“…Higher food uptake, due to acidification, has been described for several marine invertebrates including bivalves (Nardi et al, 2018). And according to the observations of Lassoued et al (2019), under optimal feeding conditions, as was the case in these experiments, M. galloprovincialis remains resistant to acidification with an increase in their feeding rates. According to temperature effect, mussels, like most aquatic organisms, are not able to regulate their body temperature in accordance with surrounding environment (Mubiana and Blust, 2007), and mytilid mussels may increase their filtering activity simultaneously as the temperature increases .…”

“…Header tanks were used to supply the experimental tanks via peristaltic pumps (ISMATEC R ) by a continuous flow rate of 9 mL min -1 . The flow rate applied enabled removal of ammonium and other waste products due to mussel metabolism or bacteria (for more specifications see Lassoued et al, 2019). Experimental tanks were composed by a total of sixteen polyethylene 9-L rectangular tanks (34×23×19 cm; LxWxH) with a middle division done by a rectangular polyethylene peace to separate mussels according the origin but sharing the same seawater.…”

“…After the correct establishment of the mussels to the experimental tanks, four different treatments were applied with 3 replicates each. The first treatment (control) was selected by using the measured pCO 2 levels in the Galician Rias recorded between summer 2017-2018 according to Lassoued et al (2019) (average CO 2 recorded: 478±119 µatm). Therefore, nominal level of CO 2 in controls was established in 400 µatm (Treatment 1, T1).…”

Ecological state of the environment and phenotypic characteristics of mussel Mytilus galloprovincialis Lamarck, 1873 in the Neum Bay (Bosnia and Herzegovina)

“…In the recent studies, shells are used as a model for determining the impact of climate change. Shell thickness is mentioned as a parameter that is subject to these influences (Martinez et al 2018, Babarro et al 2020, Lassoued et al 2021). Given the great economic importance of this species, it is not surprising that the large number of studies and scientific analyzes have been conducted with the aim to protect the populations of this species.…”

Sex-specific digestive performance of mussels exposed to warming and starvation

“…Ongoing ocean climate warming imposed more challenges of shallow-water ectotherms, such as shellfish, being exposed to beyond-optimal growth temperatures (Vajedsamiei et al, 2021). Lassoued et al (2021) pointed out that the impact of temperature on the metabolism and growth of marine organisms is an important driving stressor for their adaptation and warming of ocean would affect all their physiological activities to a large extent (Lassoued et al, 2021).…”