Manometric Assessment of interstitial microalgae production in two estuarine sediments

Oxygen production and comsumption rates were determined for the various communities (plankton, sediment, and seagrass-plus-epiphytes) associated with 2 adjacent seagrass communities, one dominated by Zostera marina and the other by Ruppia maritima. Annual estimates of gross production summed for all communities were high compared to other reports (ca 1600 gC m-' and 1100 gC m-* in the 2. marina and the R. maritima dominated communities, respectively). Plankton and sediment communities accounted for ca 45 and 36 % in the 2 areas, respectively. Seasonal patterns of production for the 2 areas differed. In the 2. marina area, plankton and sediment production dominated during summer, whereas in the R. maritima area production of seagrass (plus epiphytes) dominated throughout the study. Temporal trends for oxygen production and consumption of the plankton and sediment components corresponded closely and suggested direct in situ utilization. However, a lag observed between production and consumption in the seagrass-plus-epiphyte component indicated indirect utilization mediated by microbially dominated decomposition and remineralization processes.The ratio of annual gross production to dark respiration (P:R) exceeded 1.0 in both seagrass communities and for all components, suggesting net export and/or burial of carbon in these systems.

Section: Discussionsupporting

confidence: 80%

Oxygen production and consumption associated with the major autotrophic components in two temperate seagrass communities

Murray¹,

Wetzel²

1987

“…Most benthic microalgal studies from shallow or intertidal systems have found seasonal fluctuations in standing crop (Grantved 1960, 1962, Round 1960, Gargas 1970, Leach 1970, Gruendling 1971, Joint 1978, van den Hoek et al 1979, Colijn & Dijkema 1981, while others have found no seasonal fluctuations (Pamatmat 1968, Steele & Baird 1968, Riznyk & Phinney 1972, Cadee & Hegeman 1974, Riznyk et al 1978. Both situations were encountered in the results of the present study.…”

Section: Seasonal Fluctuationssupporting

confidence: 57%

“…Light penetration decreases with decreasing sediment particle size (Gomoiu 1967). Riznyk & Phinney (1972) found that sediment grain size was an important factor in determining benthic microalgal production, and Admiraal (1980) has emphasized that irradiance level may be important in determining the spatial distribution of benthic microalgae. Davis & McIntire (1983) found that the spatial patterns of sediment chlorophyll a were associated with sediment type in Netarts Bay, Oregon.…”

Section: Spatial Distributionmentioning

confidence: 99%

Ratio-based trophic niche breadths of fish, the Sheldon spectrum, and the size-efficiency hypothesis

Lukatelich¹,

McComb²

1986

Measurements were made of benthic microalgal biomass (chlorophyll mg m-2) and concentration (chlorophyll, pg g-' dry welght of sediment) from the Peel-Harvey estuarine system, Western Austral~a. Most chlorophyll was In the top 1 cm of s e d~m e n t , and less than 10 % of chlorophyll a was non-functional as determined by hexane extraction. Highest biomass occurred at shallow sites and on coarse sandy sedlments. Biomass was hlgher In Harvey (202 mg m-2) than Peel ( l 0 7 nlg m r 2 ) in summer when there was a large population of macroalgae In Peel; biomass was s~m i l a r in winter (Harvey 163 m g m-2. Peel 151 mg m-2). Biomass increased w~t h the onset of riverine nutrient input and decreased when blooms occurred in the water column. Except during Nodularia blooms, the biomass (chlorophyll) of b e n t h~c m~croalgae greatly exceeded ( e g 40 times) the biomass of chlorophyll In the water column above. In summer much of the chlorophyll of the water column was d u e to wlnd st~rrlng of benthic m~croalgae. The poss~ble importance of benthic mlcroalgae to the productlvlty of shallow systems is emphasized.

“…4 . Propp et al (1980) with those of others investigating benthic primary productivity differences between coarse and fine-grained sediments in estuarine and marine ecosystems (Riznyk & Phinney 1972, Propp et al 1980. Ammonium was the dominant form of inorganic nitrogen released from sandy sediments, with elevated fluxes occurring in late spring and summer.…”

Section: A Mg/mmentioning

confidence: 97%

Sediment-water column oxygen and nutrient fluxes in nearshore environments of the lower Delmarva Peninsula, USA

Reay¹,

Gallagher²,

Simmons³

1995

Sediment-water column exchanges of oxygen, dissolved inorganic nltrogen (DIN) and dissolved inorganic phosphorus (DIP) were measured in situ over an annual cycle for sandy and silt-clay sediment types in a shallow Chesapeake Bay (USA) inlet. Benthic oxygen and inorganic nutrient fluxes differed between sediment types. Based on metabolic rate estimates and photosynthetic pigment concentrations, nearshore sandy sediments were more productive than silt-clay sediments. Overall benthic community respiration rates were 872 pm01 m-' h" for sandy sediments and 2220 pm01 m-2 h-' for siltclay sediments. Elevated ammonium and DIP sediment fluxes were associated with silt-clay sediments. Sandy and silt-clay sedlment ammonium fluxes ranged from -44 to 358 and -30 to 615 pm01 m-' h-', respectively, with DIP fluxes ranging from -5.3 to 42.0 and -3.3 to 35.7 pm01 m-2 h-' Negative nutrient flux values denote sediment uptake. Sediment ammonium and DIP fluxes were dependent on benthic aerobic respiration rates for silt-clay sediments. In contrast, sandy sediment ammonium fluxes were less dependent and DIP fluxes showed no relationship to benthic aerobic respiration rates. Ammonium and DIP flux rates were significantly reduced in transparent chambers as compared to opaque chambers indicating the importance of the benthic microalgal community. On an annual basis, sandy sediments could supply 11 % of the phosphorus and 6 % of the phytoplankton nitrogen requirements based on gross productivity estlrnates, whereas silt-clay sediments could supply 11 and 14 %, respectively. Positive correlations between sandy and silt-clay sediment DIN fluxes and phytoplankton DIN assimilatory demands emphasize the importance and interdependence of sediment heterotrophic and water column autotrophic processes. Short water column DIN and DIP turnover times, on the order of hours, were characteristic of summer conditions when water column nutrient concentrations were low and silt-clay sediment nutrient fluxes high. Conversely, nutrient turnover times on the order of days were characteristic of winter conditions when water column nutrient concentrations were high and sediment nutrient fluxes low.