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Sponge mass mortalities in a warming Mediterranean Sea: are cyanobacteria-harboring species worse off?

Cebrian E, Uriz MJ, Garrabou J, Ballesteros E - PLoS ONE (2011)

Bottom Line: A laboratory experiment confirmed that the cyanobacteria harbored by I. fasciculata displayed a significant reduction in photosynthetic efficiency in the highest temperature treatment.The sponge disease reported here led to a severe decrease in the abundance of the surveyed populations.It represents one of the most dramatic mass mortality events to date in the Mediterranean Sea.

View Article: PubMed Central - PubMed

Affiliation: Universitat de Girona, Facultat de Ciències, Departament de Ciències Ambientals, Girona, Spain. emma.cebrian@udg.edu

ABSTRACT
Mass mortality events are increasing dramatically in all coastal marine environments. Determining the underlying causes of mass mortality events has proven difficult in the past because of the lack of prior quantitative data on populations and environmental variables. Four-year surveys of two shallow-water sponge species, Ircinia fasciculata and Sarcotragus spinosulum, were carried out in the western Mediterranean Sea. These surveys provided evidence of two severe sponge die-offs (total mortality ranging from 80 to 95% of specimens) occurring in the summers of 2008 and 2009. These events primarily affected I. fasciculata, which hosts both phototrophic and heterotrophic microsymbionts, while they did not affect S. spinosulum, which harbors only heterotrophic bacteria. We observed a significant positive correlation between the percentage of injured I. fasciculata specimens and exposure time to elevated temperature conditions in all populations, suggesting a key role of temperature in triggering mortality events. A comparative ultrastructural study of injured and healthy I. fasciculata specimens showed that cyanobacteria disappeared from injured specimens, which suggests that cyanobacterial decay could be involved in I. fasciculata mortality. A laboratory experiment confirmed that the cyanobacteria harbored by I. fasciculata displayed a significant reduction in photosynthetic efficiency in the highest temperature treatment. The sponge disease reported here led to a severe decrease in the abundance of the surveyed populations. It represents one of the most dramatic mass mortality events to date in the Mediterranean Sea.

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Related in: MedlinePlus

The effective quantum yield (ΦPSII) and photosynthetic electron transfer (ETR) during the experiment for the "control,” “medium” and “extreme” treatments.Bars represent standard errors.
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pone-0020211-g009: The effective quantum yield (ΦPSII) and photosynthetic electron transfer (ETR) during the experiment for the "control,” “medium” and “extreme” treatments.Bars represent standard errors.

Mentions: The effective quantum yield (ΦPSII) and the photosynthetic electron transfer (ETR) were similar for all specimens at the beginning of the experiment (ANOVA F-test; p>0.1; Fig. 9). At the end of the experiment, photosynthetic parameters were significantly lower in I. fasciculata specimens submitted to extreme temperatures, compared to specimens submitted to low (control) and medium temperatures, which did not differ between them (Table 4, Fig. 9). Photosynthesis was inhibited in specimens submitted to extreme temperatures because both ΦPSII and ETR significantly decreased to nearly zero at the end of the experiment (Table 4, Fig. 9).


Sponge mass mortalities in a warming Mediterranean Sea: are cyanobacteria-harboring species worse off?

Cebrian E, Uriz MJ, Garrabou J, Ballesteros E - PLoS ONE (2011)

The effective quantum yield (ΦPSII) and photosynthetic electron transfer (ETR) during the experiment for the "control,” “medium” and “extreme” treatments.Bars represent standard errors.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3105983&req=5

pone-0020211-g009: The effective quantum yield (ΦPSII) and photosynthetic electron transfer (ETR) during the experiment for the "control,” “medium” and “extreme” treatments.Bars represent standard errors.
Mentions: The effective quantum yield (ΦPSII) and the photosynthetic electron transfer (ETR) were similar for all specimens at the beginning of the experiment (ANOVA F-test; p>0.1; Fig. 9). At the end of the experiment, photosynthetic parameters were significantly lower in I. fasciculata specimens submitted to extreme temperatures, compared to specimens submitted to low (control) and medium temperatures, which did not differ between them (Table 4, Fig. 9). Photosynthesis was inhibited in specimens submitted to extreme temperatures because both ΦPSII and ETR significantly decreased to nearly zero at the end of the experiment (Table 4, Fig. 9).

Bottom Line: A laboratory experiment confirmed that the cyanobacteria harbored by I. fasciculata displayed a significant reduction in photosynthetic efficiency in the highest temperature treatment.The sponge disease reported here led to a severe decrease in the abundance of the surveyed populations.It represents one of the most dramatic mass mortality events to date in the Mediterranean Sea.

View Article: PubMed Central - PubMed

Affiliation: Universitat de Girona, Facultat de Ciències, Departament de Ciències Ambientals, Girona, Spain. emma.cebrian@udg.edu

ABSTRACT
Mass mortality events are increasing dramatically in all coastal marine environments. Determining the underlying causes of mass mortality events has proven difficult in the past because of the lack of prior quantitative data on populations and environmental variables. Four-year surveys of two shallow-water sponge species, Ircinia fasciculata and Sarcotragus spinosulum, were carried out in the western Mediterranean Sea. These surveys provided evidence of two severe sponge die-offs (total mortality ranging from 80 to 95% of specimens) occurring in the summers of 2008 and 2009. These events primarily affected I. fasciculata, which hosts both phototrophic and heterotrophic microsymbionts, while they did not affect S. spinosulum, which harbors only heterotrophic bacteria. We observed a significant positive correlation between the percentage of injured I. fasciculata specimens and exposure time to elevated temperature conditions in all populations, suggesting a key role of temperature in triggering mortality events. A comparative ultrastructural study of injured and healthy I. fasciculata specimens showed that cyanobacteria disappeared from injured specimens, which suggests that cyanobacterial decay could be involved in I. fasciculata mortality. A laboratory experiment confirmed that the cyanobacteria harbored by I. fasciculata displayed a significant reduction in photosynthetic efficiency in the highest temperature treatment. The sponge disease reported here led to a severe decrease in the abundance of the surveyed populations. It represents one of the most dramatic mass mortality events to date in the Mediterranean Sea.

Show MeSH
Related in: MedlinePlus