The Role of Aquatic Microcosms in Ecotoxicologic Research as Illustrated by Large Marine Systems

Gearing, J. N.

doi:10.1007/978-1-4612-3520-0_15

Cited by 20 publications

(10 citation statements)

References 214 publications

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“…Gearing 1989, Beyers & Odum 1993. Although previous investigators have postulated that experimental observations of nutrient fluxes might be affected 'by container dimensions (e.g.…”

Section: Implications For Nutrient Cycling Experimentsmentioning

confidence: 99%

Nutrient uptake in experimental estuarine ecosystems:scaling and partitioning rates

Chen¹,

Petersen²,

Kemp³

2000

Mar. Ecol. Prog. Ser.

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Studies of nutrient cycling and enrichment in aquatic ecosystems are commonly conducted in enclosed experimental ecosystems. Although there is considerable information about how the dimensions of natural aquatic ecosystems influence nutrient cycling processes, little is known on how nutrient cycling studies might be affected by the physical scales of experimental enclosures. In the present study, replicate (n = 3) cylindrical containers of 5 dimensions with 3 volumes (0.1, 1.0, 10 m3), 3 depths (0.46, 1.0, 2.15 m), and 5 diameters (0.35, 0.52, 1.13, 2.44, 3.57 m) were established and subjected to pulsed additions of dissolved inorganic nutrients (DIN, Pod3-, Si) in summer and autumn experiments. Consistent with common experimental protocols, walls of these containers were not cleaned of periphytic growth during the 8 wk studies. Nutrient concentrations in experimental ecosystems were low prior to nutrient-pulse additions and exhibited exponential depletion following treatments. Overall, larger containers had lower net uptake rates and higher nutrient concentrations than did smaller tanks. Relative contributions of planktonic, benthic and wall periphytic communities to total nutrient uptake varied in relation to dimensions of experimental systems. In general, net uptake rates by planktonic communities were inversely related to water depth, with higher rates associated with increased mean Light-energy in shallower systems. Indirect estimates of benthic uptake rates, which were relatively low in all but the shallowest systems, tended also to be inversely related to depth and directly proportional to light levels at the sediment surface. In contrast, nutrient uptake by wall communities (per water volume) was inversely related to the radius of experimental containers. Differences in the 2 container dimensions, depth and radius, accounted for more than 90 % of the variance in both net nutrient uptake by the whole ecosystem and the molar ratio of DIN/POd3-concentrations in the water column. Similarly, differences in net nutrient uptake rates among experimental ecosystems of different dimensions could be explained by the relative partition-, ing of rates among planktonic, periphytic, and benthic habitats. These results demonstrated that the physical dimensions of experimental ecosystems can have profound effects on measured nutrient dynamics. We also suggest that many of these experimental observations may be relevant also to more genera1 scaling relations for nutrient cycling in natural aquatic ecosystems.

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“…Gearing 1989, Beyers & Odum 1993. Although previous investigators have postulated that experimental observations of nutrient fluxes might be affected 'by container dimensions (e.g.…”

Section: Implications For Nutrient Cycling Experimentsmentioning

confidence: 99%

Nutrient uptake in experimental estuarine ecosystems:scaling and partitioning rates

Chen¹,

Petersen²,

Kemp³

2000

Mar. Ecol. Prog. Ser.

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“…Use of experimental ecosystems, particularly in lacustrine and estuarine research, has grown rapidly over the last 3 decades, and the many applications of mesocosms have been well documented (e.g. Giesy 1980, Grice & Reeve 1982, Gearing 1989, Lalli 1990, Beyers & Odum 1993. Mesocosms have been particularly valuable in studies of eutrophication and other perturbations in coastal marine ecosystems (e.g.…”

Section: Introductionmentioning

confidence: 99%

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

Chen

Petersen

1997

Mar. Ecol. Prog. Ser.

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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

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“…Consequently, a variety of in situ enclosure experiments have been developed and successfully used to evaluate the potential hazard of chemicals at the ecosystem level (Lee et al 1977;Dortland 1980;Grice & Reeve 1982;Lewis et al 1986;Gearing 1988; Code 61 1, PO Box 699, NIZWA, Sultance of Oman. Takahashi 1990;Wangberg et al 1991).…”

Section: Introductionmentioning

confidence: 99%

The use of field enclosure experiments to study the effect of pesticides on lake phytoplankton

et al. 1996

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An outdoor enclosure experiment was carried out to study the effect of some selected pesticides on phytoplankton of Lake Omdalsvann, Norway. The experiment lasted 2 weeks during 1990 (July/August). The pesticides tested were chlorosulfuron (herbicide), propiconazole (fungicide), dimethoate (insecticide) and glyphosate (herbicide). The pesticides were tested at three concentration levels (1 pg L-l, 10 p, g L-' and 100 pg L-') of their active ingredients. Samples for phytoplankton analysis were collected twice each week. The species richness differed greatly among the experimental bags. All treatments resulted in a significant (P. 0.05) decrease in species number compared with the results of the control. At the same time, great differences did exist in algal biomass in response to different pesticides tested. The pattern of biomass deviation from control (positive or negative) and magnitude (significant or non-significant, at P = 0.05) were mainly dependent on toxicant type, concentration and the exposure time. Shannon-Wiener diversity indices ranged between 2.69 and 2.76. The index values decreased significantly at all pesticide treatments with lowest values usually recorded 2 days after adding the pesticides. The biomass of some natural algal taxa varied quite independently not only to the different pesticides but also to their concentrations; a finding which supports the concept of species-dependent variation in algal sensitivity to chemicals. In situ toxicity testing seems to be a reliable protocol to generate more realistic data necessary for environmental protection.

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The Role of Aquatic Microcosms in Ecotoxicologic Research as Illustrated by Large Marine Systems

Cited by 20 publications

References 214 publications

Nutrient uptake in experimental estuarine ecosystems:scaling and partitioning rates

Nutrient uptake in experimental estuarine ecosystems:scaling and partitioning rates

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

The use of field enclosure experiments to study the effect of pesticides on lake phytoplankton

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