Climate change: underwater forest decline

Wernberg T., Thomsen M. S., Tuya F., Kendrick G. A., Staehr P. A. & Toohey B. D. (2010) Decreasing resilience of kelp beds along a latitudinal temperature gradient: potential implications for a warmer future. Ecol Lett 13, 685-94.

Aim: 
To assess the links between physiological (photosynthesis) and ecological (abundance, recruitment and recovery) performance of the kelp Ecklonia radiata across a temperature gradient
Type of Study: 
Comparative experiment (surveys and manipulations along natural gradient)
Key Results: 
Strong negative relationship between annual mean ocean temperature and the temperature sensitivity of both maximum net photosynthesis and dark respiration. Increasing intensity of disturbance affected photosynthetic traits, but the magnitude of the effect differed between cool and warm ocean climate with the effect being smaller under warm compared with cool conditions (F: 13% vs. 28%, ETRmax: 9% vs. 24%). There was an interaction between ocean climate and intensity of disturbance, with higher recruitment following severe compared with moderate disturbance in the cool climate, but the reverse in the warm ocean climate. An identical pattern was observed for recruit growth. In contrast to rapid recovery in the cool climate, these short-term effects on recruit performance translated into suppressed canopy recovery almost 2 years later in the warm climate.
Treatments: 
High vs low temperature, intact vs partial loss vs complete canopy loss
Response: 
Warning not to rely solely on inventories of distribution and abundance to evaluate ecosystem function
Models: 
ANOVA
Reviewer: 
Thomas Wernberg
Locations: 
Southwestern Australia, Kalbarri, Jurien Bay, Perth, Hamelin Bay
Response variable : 
Photosynthesis (PAM fluoumetry), abundance (counts of individuals), net recruitment (change in counts), growth (length increase), recovery (change in numbers of ault sporophyes)
Replication: 
2 spatially replicated temperature treatments (4 locations), 3 sites within each location, 6 replicate plots of each canopy manipulation at each site
Ecosystem: 
Temperate reef
Full Reference: 
Wernberg T., Thomsen M. S., Tuya F., Kendrick G. A., Staehr P. A. & Toohey B. D. (2010) Decreasing resilience of kelp beds along a latitudinal temperature gradient: potential implications for a warmer future. Ecol Lett 13, 685-94.