Processing of microbial biomass by an intertidal reef community

Abstract

Intertidal reef communities dominated by filter feeding organisms (such as the American oyster Crassostrea mrginjca) are a prominent feature of some marsh-estuarine systems of the southeaste m United States. Such reef communities may be considered as major components in the coupling of aquatic and benthic systems within the marsh. The ability of the reef community to remove suspended microbial biomass (as ATP) was investigated through the use of a 10 m long plexiglas tunnel that covered 7.9 m2 of reef surface. Generally, there was a net loss of suspended microbial biomass as water flowed over the reef. Microbial biomass levels were lower at the output from the tunnel than at the input to the tunnel for 61 % of flood tides and 76 '10 of ebb tides. Determinations of net transport revealed that total microbial biomass was imported to the reef on 26 of 33 flood-tide phases and 27 of 33 ebb-tide phases. Import rates ranged between 0.1 1 and 5.39 pg ATP S-' during flood tides and between 0.46 and 18.20 pg ATP S -' during ebb tides. Annually 55 g ATP were imported to the reef community. T h s import rate corresponded to an equivalent carbon flow of 1750 g C m-' yr.' The net flow of microbial carbon into the reef community was 20 times greater than reported estimates of particulate organic carbon flow from the entire marsh system to the ocean.

Effects of filter-feeding by the ribbed mussel Geukensia demissa on the water-column microbiota of a Spartina alterniflora saltmarsh

“…Filtration of living carbon by Geukensia demissa represents only a very small fraction of the total carbon produced in the salt-marsh system or exported from salt marshes to the nearshore region (Chrzanowski et al 1982), in strong contrast with the impact of filtration by salt marsh oyster reef communities where net importation of living carbon can greatly exceed the estimated export of total POC from the salt-marsh system (import = 1750g C m-' yr-l: Chrzanowski et al 1986). Thus, while grazing on microbes probably provides a substantial fraction of the carbon requirements of G. demissa, strongly influences the abundance of microbes in water exposed to the marsh surface, and may be important to microbial trophodynamics within the salt-marsh creek water column, our data suggest it is relatively unimportant in terms of total flux of living carbon in the salt marsh system.…”

“…The use of flumes and other enclosures, or other means of repeatedly sampling specific water parcels containing natural particles (e.g. Jordan & Valiela 1982, Wright et al 1982, Dame et al 1985, Chrzanowski et al 1986, Lucas et al 1987, Peterson & Black 1987, Frechette et al 1989) may be more appropriate when the goal is to evaluate the impact of filtration by field populations.…”

Impacts of Aquaculture on Habitats and Best Management Practices (BMPs)

“…Although they did not find substantial differences in water quality parameters, phytoplankton was constantly available and removed by the Pacific oysters (Crassostrea gigas). Chrzanowski et al (1986) investigated the ability of an oyster reef community to remove suspended microbial biomass and observed significant reduction in the suspended microbial biomass. Toro et al (1999) found a significant negative relationship between oyster growth and amount of particulate inorganic and organic matter in water.…”