Spatial and temporal scaling of periphyton growth on walls of estuarine mesocosms

Abstract

Although experimental ecosystems a r r bdsic and versatile tools w~d e l y used In coastal research periphyt~c glo\vth on container walls IS an ~n t n n s l c artifact that must be considered when lnterprctlng results To bettel understand holv this a1 tifact may confound extrapoldtion of results f~o m controlled exper~ments to conditions In natural estudr~ne ecosystems w e examined ho\v wall perlphyton varied wlth container size and shape in summer and dutunin expenments Kepllcate ( n = 3) cvlind11ca1 mesocosms ot 3 volumes (0 1 1 0 10 m') werr establ~shed In both constant-depth (depth -1 m) and conbtant-shape (radiuddepth = 0 56) serles \ l e~o c o s n~s were in~tlated with unfiltered estudrine water and homogenized s e d~m e n t s Pel~phyton b~ornass and gross primary production (GPP) per unlt of wall area ~n c l e a s e d wlth incredslng r a d~u s ( I ) or decreasing ratio of \vall area (A,,,) to water volume ( V ) for mesocos~ns In both s e r~e s (A,,/V = 2/r) As a consequence per~phyton biornass and metabol~sm expressed per u n~t of water volume Increased as a quadratic functlon of increasing A,, / V ratlo Results also suggest a secondary s c a l~n g effect whereby wall perlphyton qrowth may he directly reldted to mesocosm depth although mechanisms for th15 effect I enialn uncledr Slgnlflcant correlations between perlphyton biomass (per m2 wall area) and 3 rnv~ronmental f a c t o~s (11ght a t t r n u a t~o n c o e f f~c~e n t nutnent concentration and zooplankton dbundance) suqqest that these factors may have played Important roles In r e g u l a t~n g wdll grolvth Add~tlonally, effects of wall penphyton growth on plankton community dynamics were also indicated by the signlflcant n e g a t~v e relat~ons between penphyton biomass and measures of both phytoplankton and zooplankton abundance The overall effect of periphyton on the e\perlmental ecosystems was evldent In the fact that perlphyton accounted for over 5 0 " ) of total ecosystem GPP and b~o m a s s after 2 to 4 ~v k of these expenments For mesocosm experimc.nts d e s~g n e d to examlne dyndmics of planktonic-benth~c ecosystems, our ~e s u l t s lmply that growth of wall periphvton which 1s controlled b\l fact015 s c a l~n g to the ~a d i u s of expenmental ecosystems tends to domintlte major b~otic pools and ratcs withln weeks

Nutrient uptake in experimental estuarine ecosystems:scaling and partitioning rates

“…This biomass trend can be explained as a consequence of phytoplankton competition with wall periphyton for limited nutrients, where narrow systems with more periphyton growth tended to have less phytoplankton (e.g. Chen et al 1997). Thus, what appears to be an inverse depth effect (Fig.…”

“…Growth of periphytic bacteria and algae on mesocosm walls is typically rapid, reaching significant levels within 2 to 3 d (e.g. Kevern et al 1966, Kuiper 1981) and often dominating both biomass and productivity within relatively short (7 d) time periods (Chen 1998). Even for systems with periodic wall cleaning, rapidly growing periphyton can still alter metabolic processes in planktonic and benthic communities (Dudzik et al 1979, Chen 1998.…”

“…Chen et al 1997, Berg et al 1999). In one of these studies, it was demonstrated that vertically integrated rates of primary productivity (per unit area) for whole ecosystems are independent of mixedlayer depth under light-limited conditions, but are di--rectly proportional to depth under conditions of nutrient limitation .…”

Effect of oysters Crassostrea virginica and bottom shear velocity on benthic-pelagic coupling and estuarine water quality

“…Within the first 3 d of each experiment we added a nutrient spike of ammonium and soluble reactive phosphorus (SRP) at the Redfield ratio, increasing initial ammonium and SRP levels in the tanks by about 25 and 1.6 µM, respectively, to stimulate a phytoplankton bloom. We cleaned mesocosm walls of wall periphyton biweekly or more often to minimize wall growth (Chen et al 1997(Chen et al , 2000.…”

Marine ecosystem community carbon and nutrient uptake stoichiometry under varying ocean acidification during the PeECE III experiment

“…Schulz et al (2008) suggest from ammonium measurements that there must have been significant remineralisation in the lower 1.5 m of the mesocosms, especially in the high CO 2 treatments fuelled by increased carbon export. The role of benthic organisms living on the walls of the mesocosm enclosures, which has been shown to impact biogeochemical cycling during mesocosm studies (Chen et al, 1997;Berg et al, 1999;Petersen et al, 1999), was not studied.…”