Seasonality of in situ respiration rate in three temperate benthic suspension feeders

Abstract

Natural respiration rates of suspension feeders in temperate ecosystems are still poorly known. This lack of information constrains our understanding of the functioning and dynamics of benthic marine ecosystems in temperate areas.We examined the in situ seasonal variation in respiration rate of three benthic suspension feeders (a sponge, an ascidian, and a gorgonian) in northwestern Mediterranean sublittoral communities using a recirculating flow respirometry system. The in situ technique is shown to be highly applicable to seasonal studies of the physiological energetics of benthic suspension feeders. Respiration rates of the three species varied two‐ to threefold through the annual cycle, exhibiting a marked seasonal pattern but showing no daily cycle or significant day‐today variability within months. The respiration rate of the sponge and ascidian, active suspension feeders, increased with temperature. The respiration rate of the gorgonian, a passive suspension feeder, did not correlate with temperature. We estimated a Q10 of 1.1, which indicates that respiration rate in this species is not highly dependent on temperature. Synthesis of new tissue of some Mediterranean benthic suspension feeders, such as gorgonians, does not correlate with temperature, which allowed us to isolate the effects of temperature and synthesis of new tissue on respiration rate. Synthesis of new tissue increased respiration rate of the gorgonian by ~40%. The low rate of synthesis of new tissue during summer, together with the contraction of polyps and the low Q10, explains the low respiration rates of the gorgonian observed during the period of highest temperature. These low respiration rates support the hypothesis that energy limitations may underlie summer dormancy in some benthic suspension‐feeding taxa in the Mediterranean.

Protein, carbohydrate, lipid concentrations and HSP 70–HSP 90 (stress protein) expression over an annual cycle: useful tools to detect feeding constraints in a benthic suspension feeder

“…Feeding (energy input, lg carbon polyp À1 day À1 ·100), from the zooplankton fraction (Coma et al 1994) and the <100 lm detritus and <100 lm live carbon (Ribes et al 1999). Respiration (mg À1 oxygen organic matter tissue h À1 ) from Coma et al (2002). Reproduction (lg carbon polyp À1 day À1 ·100; m=male and f=female) from Coma et al (1995aComa et al ( , 1998b.…”

“…The biology of P. clavata has been extensively studied during the last decade (e.g. Weinberg 1978;Mistri and Ceccherelli 1994;Coma et al 1998aComa et al , 2002. Furthermore, stress protein expression in P. clavata tissue cannot be related with highly fluctuating temperatures (heat shock response), because the cnidarian lives at 15-60 m depth (Gili and Ros 1985) and changes in temperature in the spring-summer period do not exceed 2-3°C.…”

Growth and photosynthesis of two Mediterranean corals, Cladocora caespitosa and Oculina patagonica, under normal and elevated temperatures

“…Necrosis was observed in gorgonians and sponges when temperatures remained above or equal to 24°C over several weeks and coincided with the occurrence of opportunistic organisms (Cerrano et al, 2000;Cerrano et al, 2001). Energy shortage was also observed in taxa exhibiting summer dormancy such as anthozoans and sponges (Coma et al, 2000). Therefore, the elevated temperature, together with the stability of the water column, were suggested to be the most likely cause of benthic mortality because they affected a wide variety of taxa down to a depth of 40·m (above the lowered thermocline), over a large geographical area (Coma et al, 2002;Coma and Ribes, 2003;Linares et al, 2005).…”

Organic matter input and processing in two contrasting North Sea sediments: insights from stable isotope and biomass data

“…Anemones of similar size to those found at Stn 115 FINE captured a minimum of 15 nauplii min -1 in an experimental setup (Anthony 1997). Assuming that the summer population of S. troglodytes (~250 specimens m -2 , this study) preys on a similar amount of nauplii and assuming 0.00025 mg C nauplius ; Coma et al 2002), which is 83% of the community respiration. Both conservative rough calculations suggest an important role of predatory anemones in the transfer of pelagic carbon to the benthic community.…”