The effect of grazing by a gastropod, Nassarius obsoletus, on the benthic microbial community of a salt marsh mudflat

Pace, Michael L.; Shimmel, Stephen M.; Darley, W. Marshall

doi:10.1016/0302-3524(79)90109-9

Cited by 81 publications

(39 citation statements)

References 29 publications

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“…obs.). I. obsoleta can exist on an algal diet, and at natural densities, its grazing activity can significantly reduce microalgal biomass and productivity (Pace et al 1979). It is unknown whether the relative enrichment in 15N in I. obsoleta, relative to the other grazers examined, is due to greater assimilation of animal tissue, or from grazing plant material with a heavier S1'N value.…”

Section: Resultsmentioning

confidence: 99%

The role of standing dead Spartina alterniflora and benthic microalgae in salt marsh food webs:considerations based on multiple stable isotope analysis

Paerl

1995

Mar. Ecol. Prog. Ser.

397

289

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ABSTRACT-The stable isotope compositions (C, N, and S) of hve, senescent, and standing dead Spartina alterniflora were compared in order to determine the effects of aerial decomposition on the isotopic signature of aboveground S. dlterniflora tissue entering the food chain. Aerial decomposition of aboveground S. alterniflora resulted in a 6 to 18% increase in P S , and a 2 to 3 % decrease in 615N values; 613c values were unchanged. We describe mechanisms whereby the activity of fungi and epiphytic microorganisms may contribute to the observed shlfts in and 6I5N, respectively. The 613c value of salt marsh benthic and eplphytic microalgae ranged from -13.0% in summer to -17.6%0 in early spring. Average 6'" values of microalgae and standing dead S. altemiflora were -0 3 and l.?%, respectively, reflecting the activity of NZ-fixing microorganisms. The 615N values for omnivorous and herbivorous salt marsh macrofauna ranged between 7.5 and 2.2% and for predatory Fundulus spp. averaged 9.2%. Given a presumptive + 3 % trophic shift in N assimilation, these results suggest that N2-fixing microorganisms associdted with microalgal communities were an important source of N to salt marsh consumers. The 6% 6'"N, and 6"' s values of primary producers were compared to the values of the following consumers: Fundulus spp., Uca spp., Ilyanassa obsoleta, and Littoraria irrorata. 6I3C VS 6 1 5~ and 613C vs 63JS dual isotope plots demonstrated that microalgae and standing dead S. alternjflora are important food resources in the North Carolina (USA) marshes we sampled. In addition, a compilation of literature values suggests that this is true in salt marshes throughout the East and Gulf coasts of North America. Future isotope studies of marsh food webs should include detrital Spartina spp. material in analyses of trophic structure.

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Section: Resultsmentioning

confidence: 99%

The role of standing dead Spartina alterniflora and benthic microalgae in salt marsh food webs:considerations based on multiple stable isotope analysis

Paerl

1995

Mar. Ecol. Prog. Ser.

397

289

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“…Darley et al 1981;Posey et al 1995) to enhance and herbicides (Hentschel and Jumars 1994) to retard algal growth. Top-down effects have been studied via manipulation of macrofaunal grazers (,Connor et al 1982;Darley et al 198 1;Pace et al 1979). Smdies of contaminants, however, generally include little consideration of indirect (top-down or bottom-up) effects on I:ommunities.…”

Section: Discussionmentioning

confidence: 99%

“…Microalgal biomass may be reduced by macrofaunal grazing pressure (e.g. Connor et al 1982;Darley et al 1981;Pace et al 1979), indicating that microalgal biomass is limited by grazing pressure. Nutrients (usually N;Darley et al 1981;Posey et al 1995) or light (Estrada et al 1974) may also limit microalgal growth.…”

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confidence: 99%

Response of a benthic food web to hydrocarbon contamination

1997

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Direct and indirect effects of diesel-contaminated sediment on microalgae, meiofauna, and meiofauna-microalgae trophic interactions were examined in a microcosm study of the sediment community from a Spartina aZterniJora salt marsh. Microcosms of natural sediment were given small daily doses of contaminated sediment over a 28-d period, creating low-, medium-, and high-diesel treatment concentrations of -0.5, 5.5, and 55 ppm PAH, respectively. Diesel caused initial (within 7 h) reductions in microalgal grazing by meiobenthic harpacticoid copepods. Over longer periods of exposure (7-28 d), grazing on microalgae by copepods as a group was reduced in highdiesel treatments, primarily because of high copepod mortality. In contrast, grazing by and abundance of Cletocamptus deitersi (a copepod) was significantly enhanced in high-diesel treatments. Concurrent with reduced grazing by copepods, nematode grazing rates increased significantly in high-diesel treatments, indicating possible competition for microalgae between copepods and nematodes. In spite of transiently enhanced grazing by nematodes and C. deitersi, total meiofaunal grazing on microalgae was reduced in high-diesel treatments. Increased Chl a: pheopigment ratios in contaminated sediments were also indicative of reduced grazing pressure. A large (10X) increase in microalgal biomass was observed in high-diesel treatments and was likely a consequence of reduced meiofaunal grazing. The general responses observed in microcosms were also observed in a field study of polycyclic aromatic hydrocarbon contamination. Collectively, our data indicate that benthic microalgal biomass is controlled by meiofaunal grazing and that meiofauna may compete for limited algal resources. Furthermore, consideration of multiple trophic levels and their interactions allows a more complete and ecologically meaningful understanding of the mechanisms by which contaminants induce changes in natural communities.

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“…Although sediments in Kbnigshafen are relatively coarse grained, the macrofauna closely resembles those of other tidal areas in north western Europe (see Wohlenberg, 1937), and the species composition in the tidal zone has remained relatively stable over the last decades (Reise, 1982). From these areas and also from other tidal flats in the world, high abundances of grazers are well known (Macnae & Kalk, 1962;DSrjes, 1978;Pace et al, 1979;Branch & Branch, 1980;Race, 1982).…”

Section: Importance Of Grazing Food Chainmentioning

confidence: 93%

“…Production is used to compensate biomass losses through feeding by heterotrophs. A high abundance of herbivorous macrofauna decreased biomass and production of benthic microalgae in other areas (Hargrave, 1970;Darley et al, 1981;Pace et al, 1979;Davis & Lee, 1983;Hickman & Round, 1970;Taasen & Heisaeter, 1981;Branch & Branch, 1980;Connor et al, 1982), whereas a lower density of macrofauna may stimulate the growth of microphytobenthos (Hargrave, 1970;Connor et al, 1982), In the NereisCorophium-belt, biomass losses of microphytobenthos caused by herbivores amount to only one third to one half the losses in other communities. Thus, a higher level of microphytobenthos biomass can be maintained.…”

Section: Energy Flowmentioning

confidence: 99%

The importance of grazing food chain for energy flow and production in three intertidal sand bottom communities of the northern Wadden Sea

Asmus

1985

Helgolander Meeresunters

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In three intertidal sand bottom communities of the "K6nigshafen" (Island of Sylt, North Sea), the biomass production and respiration of phytobenthos, phytoplankton, macrozoobenthos, and in situ community metabolism were measured monthly during 1980. The study sites were characterized by different communities (Nereis-Corophium-belt, seagrass-bed, Arenicola-flat) and by a high abundance of the mollusc Hydrobia ulvae. Benthic diatoms are the major constituents of plant biomass in the Arenicola-flat. In this community, gross primary productivity amounts to 148 g C m-2 a-1.82 % of this productivity is caused by microbenthos, whereas phytoplankton constitutes only 18 %. In the seagrass-bed, gross primary productivity amounts to 473 g C m -2 a -1. 79 % of this is generated by seagrass and its epiphytes, whereas microphytobenthos contributes 19 %. In the Nereis-Corophium-belt, only microphytobenthos is important for hiomass and primary productivity (gross: 152 g C m -2 a-l). Annual production of macrofauna proved to be similar in the A_renicola-flat (30 g C m -2 a -1) to that in the seagrass-bed (29 g C m -2 a-l). Only one third of this amount is produced in the Nereis-Corophium-belt (10 g C m -2 a-l). The main part of secondary production and animal respiration is contributed by grazing H. ulvae. In the seagrass-bed, 83 % of the energy used for production is obtained from the grazing food chain. In the Arenicola-flat and the NereisCorophium-belt, the importance of non-grazing species is greater. A synchrony of seasonal development of plant biomass and monthly secondary production was observed. In the Arenicolaflat and the seagrass-bed, where density and production of macrofauna are high, a conspicuous decrease in biomass of microbenthos occurs during the warmer season, whereas in the NereisCorophium-belt primary production causes an increase in microphytobenthic biomass in summer and autumn. Energy flow through the macrofauna amounts to 69 g C m -2 a -~ in the Arenicola-flat, 85 g C m -~ a -1 in the seagrass-bed and 35 g C m -2 a -1 in the Nereis-Corophium-belt. Based on the assumption that sources of food are used in proportion to their availability, 49 g C m -2 a -1 (Arenicola-fiat), 72 g C m -2 a -1 (seagrass-bed) and 26 g C m -2 a -1 (Nereis-Corophium-belt) are estimated as taken up by the grazing food chain. All three subsystems are able to support the energy requirements from their own primary production and are not dependent on energy import from adjacent ecosystems.

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The effect of grazing by a gastropod, Nassarius obsoletus, on the benthic microbial community of a salt marsh mudflat

Cited by 81 publications

References 29 publications

The role of standing dead Spartina alterniflora and benthic microalgae in salt marsh food webs:considerations based on multiple stable isotope analysis

The role of standing dead Spartina alterniflora and benthic microalgae in salt marsh food webs:considerations based on multiple stable isotope analysis

Response of a benthic food web to hydrocarbon contamination

The importance of grazing food chain for energy flow and production in three intertidal sand bottom communities of the northern Wadden Sea

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