 |
| Titel |
CO2 and nutrient-driven changes across multiple levels of organization in Zostera noltii ecosystems |
| VerfasserIn |
B. Martínez-Crego, I. Olivé, R. Santos |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1726-4170
|
| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 11, no. 24 ; Nr. 11, no. 24 (2014-12-17), S.7237-7249 |
| Datensatznummer |
250117746
|
| Publikation (Nr.) |
 copernicus.org/bg-11-7237-2014.pdf |
|
|
|
|
|
| Zusammenfassung |
| Increasing evidence emphasizes that the effects of human impacts on
ecosystems must be investigated using designs that incorporate the responses
across levels of biological organization as well as the effects of multiple
stressors. Here we implemented a mesocosm experiment to investigate how the
individual and interactive effects of CO2 enrichment and
eutrophication scale-up from changes in primary producers at the
individual (biochemistry) or population level (production, reproduction,
and/or abundance) to higher levels of community (macroalgae abundance,
herbivory, and global metabolism), and ecosystem organization (detritus
release and carbon sink capacity). The responses of Zostera noltii seagrass meadows
growing in low- and high-nutrient field conditions were compared. In both
meadows, the expected CO2 benefits on Z. noltii leaf production were suppressed
by epiphyte overgrowth, with no direct CO2 effect on plant biochemistry
or population-level traits. Multi-level meadow response to nutrients was
faster and stronger than to CO2. Nutrient enrichment promoted the
nutritional quality of Z. noltii (high N, low C : N and phenolics), the growth of
epiphytic pennate diatoms and purple bacteria, and shoot mortality. In the
low-nutrient meadow, individual effects of CO2 and nutrients separately
resulted in reduced carbon storage in the sediment, probably due to enhanced
microbial degradation of more labile organic matter. These changes, however,
had no effect on herbivory or on community metabolism. Interestingly,
individual effects of CO2 or nutrient addition on epiphytes, shoot
mortality, and carbon storage were attenuated when nutrients and
CO2 acted simultaneously. This suggests CO2-induced benefits on
eutrophic meadows. In the high-nutrient meadow, a striking shoot decline
caused by amphipod overgrazing masked the response to CO2 and nutrient
additions. Our results reveal that under future scenarios of CO2, the
responses of seagrass ecosystems will be complex and context-dependent,
being mediated by epiphyte overgrowth rather than by direct effects on plant
biochemistry. Overall, we found that the responses of seagrass meadows to
individual and interactive effects of CO2 and nutrient enrichment
varied depending on interactions among species and connections between
organization levels. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|