Interacting climate change effects on mussels (Mytilus edulis and M. galloprovincialis) and oysters (Crassostrea gigas and Ostrea edulis): experiments for bivalve individual growth models

Abstract

The physiological response of two species of mussels (Mytilus edulis and M. galloprovincialis) and two species of oysters (Crassostrea gigas and Ostrea edulis) to temperature, oxygen levels and food concentration, factors likely to vary as a result of climate change, was determined experimentally. Bivalves of similar size from different origins were exposed to six temperatures (3, 8, 15, 20, 25 and 30 °C) at two food regimes (2 and 10 μg Chl a L−1) for 6 weeks. In a parallel running experiment M. edulis from the same batches were exposed to three different temperatures (15, 20 and 25 °C) and three different oxygen levels (30, 50 and 100%) at two food regimes (2 and >8 μg Chl a L−1) for 3–4 weeks. Survival during the experiment ranged from 93% to 100% except for the mussels exposed to 30 °C which showed 100% mortality after three to 32 days. Higher food conditions showed higher optimal temperatures for growth of mussels and oysters. In addition, at the high food treatment, reduced O2 saturation resulted in lower growth of mussels. At the low food treatment there were no differences in growth among the different O2 levels at the same temperature. At high food concentration treatment, M. edulis growth was higher with low temperature and high oxygen level. Condition index was higher at higher food concentrations and decreased with increasing temperature. In addition, condition was lower at low oxygen saturation. Lower clearance rates were observed at high food concentrations. At 100% saturation of oxygen, mussel clearance rate increased with temperature at High food regime, but not at Low food regime. Mussel clearance rates were significantly reduced with low oxygen concentrations together with high temperature. Oxygen consumption significantly increased with temperature. Oxygen saturation was the main factor affecting mussel clearance rate. High temperature and low oxygen concentration combined significantly reduced clearance rate and increased oxygen consumption. These response curves can be used to improve parameterisation of individual shellfish growth models taking into consideration factors in the context of climate change: temperature, food concentration, oxygen concentration and their interactions. The observation that abiotic factors interact in affecting mussels and oysters is an important result to take into account.

Comparing life history traits and tolerance to changing environments of two oyster species (Ostrea edulis and Crassostrea gigas) through Dynamic Energy Budget theory

“…The estimations of growth at constant food levels of 2 μg chl L -1 and 10 μg chl L -1 and temperatures ranging from 3°C to 30°C ( Kamermans and Saurel, 2022 ) were simulated for flat and Pacific oyster ( Fig. 3 ).…”

“…DEB parameters of C. gigas were retrieved from the literature ( AmP, 2021 ). Parameters of both oysters were validated using aquaculture growth data from the Limfjorden, Denmark, and the German Bight ( Pogoda et al, 2011 ) and experimental growth data at different food levels and temperatures ( Kamermans and Saurel, 2022 ).…”

“… Kamermans and Saurel (2022) measured growth of C. gigas and O. edulis under laboratory conditions at different temperatures (3, 8, 15, 20, 25 and 30°C) and two food regimes (2 and 10 μg chl a L −1 ) for 6 weeks. For the experiments, oysters were selected from the same size class; C. gigas spat had an average shell length of 21.9 ± 4.5 mm and an average wet weight of 1.13 ± 0.61 g, while O. edulis spat had an average shell length of 24.0 ± 4.2 mm and an average wet weight of 0.87 ± 0.44 g. The 12 treatments were each performed in triplicate.…”

“…Two growth curves were collected in the Limfjorden, Denmark, during aquaculture trails, and three growth curves were extracted from published grow-out experiments in the German Bight ( Pogoda et al, 2011 ). In addition, experimental growth data collected at different constant food level and temperatures were used to optimize the Arrhenius temperature parameters and to validate the DEB primary parameters ( Kamermans and Saurel, 2022 ). The DEB parameters for C. gigas , which have been published in the literature ( AmP, 2021 ), were validated using grow-out experiments in the German Bight ( Pogoda et al, 2011 ) and experimentally collected growth data at constant food and temperature ( Kamermans and Saurel, 2022 ).…”

“…In addition, experimental growth data collected at different constant food level and temperatures were used to optimize the Arrhenius temperature parameters and to validate the DEB primary parameters ( Kamermans and Saurel, 2022 ). The DEB parameters for C. gigas , which have been published in the literature ( AmP, 2021 ), were validated using grow-out experiments in the German Bight ( Pogoda et al, 2011 ) and experimentally collected growth data at constant food and temperature ( Kamermans and Saurel, 2022 ). Food availability was estimated for all validation datasets by using the average chlorophyll a (chl) concentration as the food proxy.…”