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Ocean acidification effects on mesozooplankton community development: Results from a long-term mesocosm experiment

View Article: PubMed Central - PubMed

ABSTRACT

Ocean acidification may affect zooplankton directly by decreasing in pH, as well as indirectly via trophic pathways, where changes in carbon availability or pH effects on primary producers may cascade up the food web thereby altering ecosystem functioning and community composition. Here, we present results from a mesocosm experiment carried out during 113 days in the Gullmar Fjord, Skagerrak coast of Sweden, studying plankton responses to predicted end-of-century pCO2 levels. We did not observe any pCO2 effect on the diversity of the mesozooplankton community, but a positive pCO2 effect on the total mesozooplankton abundance. Furthermore, we observed species-specific sensitivities to pCO2 in the two major groups in this experiment, copepods and hydromedusae. Also stage-specific pCO2 sensitivities were detected in copepods, with copepodites being the most responsive stage. Focusing on the most abundant species, Pseudocalanus acuspes, we observed that copepodites were significantly more abundant in the high-pCO2 treatment during most of the experiment, probably fuelled by phytoplankton community responses to high-pCO2 conditions. Physiological and reproductive output was analysed on P. acuspes females through two additional laboratory experiments, showing no pCO2 effect on females’ condition nor on egg hatching. Overall, our results suggest that the Gullmar Fjord mesozooplankton community structure is not expected to change much under realistic end-of-century OA scenarios as used here. However, the positive pCO2 effect detected on mesozooplankton abundance could potentially affect biomass transfer to higher trophic levels in the future.

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P. acuspes females’ condition.General Linear Models (GLMs) comparing the potential pCO2 effect on P. acuspes females: A) respiration rate, B) carbon content, C) prosome length, D) clutch size at the beginning of the incubation (0h), E) hatching success after 48h incubation. Error bars represent standard deviation. Colour code: red = treatment (~760 μatm pCO2), blue = control (ambient conditions). March = t19 (first phytoplankton bloom), May = t59 (decline phase of the second phytoplankton bloom).
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pone.0175851.g007: P. acuspes females’ condition.General Linear Models (GLMs) comparing the potential pCO2 effect on P. acuspes females: A) respiration rate, B) carbon content, C) prosome length, D) clutch size at the beginning of the incubation (0h), E) hatching success after 48h incubation. Error bars represent standard deviation. Colour code: red = treatment (~760 μatm pCO2), blue = control (ambient conditions). March = t19 (first phytoplankton bloom), May = t59 (decline phase of the second phytoplankton bloom).

Mentions: Regarding the P. acuspes females’ condition, none of the physiological and reproductive parameters investigated (respiration, carbon content, prosome length, clutch size, hatching success) showed a significant difference between treatments, nor in the interaction between month and treatment (p-value > 0.05; Fig 7, Table 4). However, significant differences between the first (March, t19: first phytoplankton bloom) and the second experiment (May, t59: second phytoplankton bloom) were observed. Respiration rate (Fig 7A) was lower during May compared to March (p-value = 0.001). Females’ carbon content and prosome length, as well as the hatching success after 48h incubation (Fig 7B, 7C and 7E) were not different between months, nor between pCO2 conditions. Yet, at the beginning of the incubations (0h), clutch size (Fig 7D) was significantly higher in May (p-value = 0.021). None of the interactions between pCO2 treatment and month rendered in a significant effect on the studied variables.


Ocean acidification effects on mesozooplankton community development: Results from a long-term mesocosm experiment
P. acuspes females’ condition.General Linear Models (GLMs) comparing the potential pCO2 effect on P. acuspes females: A) respiration rate, B) carbon content, C) prosome length, D) clutch size at the beginning of the incubation (0h), E) hatching success after 48h incubation. Error bars represent standard deviation. Colour code: red = treatment (~760 μatm pCO2), blue = control (ambient conditions). March = t19 (first phytoplankton bloom), May = t59 (decline phase of the second phytoplankton bloom).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5391960&req=5

pone.0175851.g007: P. acuspes females’ condition.General Linear Models (GLMs) comparing the potential pCO2 effect on P. acuspes females: A) respiration rate, B) carbon content, C) prosome length, D) clutch size at the beginning of the incubation (0h), E) hatching success after 48h incubation. Error bars represent standard deviation. Colour code: red = treatment (~760 μatm pCO2), blue = control (ambient conditions). March = t19 (first phytoplankton bloom), May = t59 (decline phase of the second phytoplankton bloom).
Mentions: Regarding the P. acuspes females’ condition, none of the physiological and reproductive parameters investigated (respiration, carbon content, prosome length, clutch size, hatching success) showed a significant difference between treatments, nor in the interaction between month and treatment (p-value > 0.05; Fig 7, Table 4). However, significant differences between the first (March, t19: first phytoplankton bloom) and the second experiment (May, t59: second phytoplankton bloom) were observed. Respiration rate (Fig 7A) was lower during May compared to March (p-value = 0.001). Females’ carbon content and prosome length, as well as the hatching success after 48h incubation (Fig 7B, 7C and 7E) were not different between months, nor between pCO2 conditions. Yet, at the beginning of the incubations (0h), clutch size (Fig 7D) was significantly higher in May (p-value = 0.021). None of the interactions between pCO2 treatment and month rendered in a significant effect on the studied variables.

View Article: PubMed Central - PubMed

ABSTRACT

Ocean acidification may affect zooplankton directly by decreasing in pH, as well as indirectly via trophic pathways, where changes in carbon availability or pH effects on primary producers may cascade up the food web thereby altering ecosystem functioning and community composition. Here, we present results from a mesocosm experiment carried out during 113 days in the Gullmar Fjord, Skagerrak coast of Sweden, studying plankton responses to predicted end-of-century pCO2 levels. We did not observe any pCO2 effect on the diversity of the mesozooplankton community, but a positive pCO2 effect on the total mesozooplankton abundance. Furthermore, we observed species-specific sensitivities to pCO2 in the two major groups in this experiment, copepods and hydromedusae. Also stage-specific pCO2 sensitivities were detected in copepods, with copepodites being the most responsive stage. Focusing on the most abundant species, Pseudocalanus acuspes, we observed that copepodites were significantly more abundant in the high-pCO2 treatment during most of the experiment, probably fuelled by phytoplankton community responses to high-pCO2 conditions. Physiological and reproductive output was analysed on P. acuspes females through two additional laboratory experiments, showing no pCO2 effect on females’ condition nor on egg hatching. Overall, our results suggest that the Gullmar Fjord mesozooplankton community structure is not expected to change much under realistic end-of-century OA scenarios as used here. However, the positive pCO2 effect detected on mesozooplankton abundance could potentially affect biomass transfer to higher trophic levels in the future.

No MeSH data available.


Related in: MedlinePlus