Biogeochemistry of Nearshore Bermuda Sediments. I. Sulfate Reduction Rates and Nutrient Generation

Hines, ME; Lyons, WmB

doi:10.3354/meps008087

Cited by 69 publications

(28 citation statements)

References 22 publications

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“…No other parameter correlated with grain size. Sedi- 3 2 TIME (days) ment nitrogen pools in this backreef were similar to those reported from various reef sites (Pigott 1977, Hines & Lyons 1982, Entsch et al 1983). Benthic nitrogen fluxes were higher than those reported from Enewetak lagoon (Harrison 1983) and from sites impacted by sewage outfall in Hawaii (Dollar 1983), but in the lower range of values reported from many temperate coastal areas (Klump & Martens 1983).…”

Section: Discussionsupporting

confidence: 68%

“…Ammonification rates reported here for the backreef sediments fall among the lower values measured in primarily silici-clastic anoxic sediments (Blackburn 1979, Klump & Martens 1983, or modelled for carbonate sediment (Hines & Lyons 1982). Ammonification rates on the backreef may be limited by organic input to the sediment.…”

Section: Discussionmentioning

confidence: 68%

“…Nitrogen regeneration is a vitally important aspect of coral reef ecosystem function and yet, to our knowledge, only indirect measurements of nitro- O Inter-Research/Printed in F. R. Germany gen regeneration in coral reef sediment exist. Pigott (1977) estimated rates of nitrogen regeneration for reef sediments based on a stoichiometric analysis of porewater concentrations while Hines & Lyons (1982) used sulfate reduction measurements to calculate nitrogen regeneration in a lagoonal-type environment.…”

Section: Introductionmentioning

confidence: 99%

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Ammonium distributions, production, and efflux from backreef sediments, St. Croix, US Virgin Islands

Williams¹,

Yarish²,

Gill³

1985

Mar. Ecol. Prog. Ser.

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Sediments in < 3 m water depth on Tague Bay backreef, St. Croix, US Virgin Islands, were sampled for grain size, Eh, pH, organic carbon, pore-water ammonium and nitrate + nitrite concentrations, ammonium production, and ammonium and nitrate + nitrite benthic fluxes. Most sampling sites had nutrient-poor, oxidized, coarse sand-sized sediments. Ammonium and nitrate + nitrite concentrations were typically < 5 PM; organic carbon was < 0.6 % g dry weight. High spatial heterogeneity on the scale of cm2 existed in all parameters measured except grain size, which decreased regularly away from the reef. We suggest that the nutrient-poor conditions were maintained by high turbulence in the environment, which would minimize organic input to the sediments and maximize resuspension and oxygenation. This view was supported by ammonification rates (mean = 70 pm01 (1 sediment)-' d-l) and benthic nitrogen fluxes which were low compared to rates reported from many temperate coastal areas. Benthic nitrogen fluxes were highly variable and averaged ?l f 95 (mean + SD) w o l ammonium m-* d-I and -5 f 40 pm01 nitrate + nitrite m-2 d-l. Local pockets of reducing sediments with ammonium concentrations > 30 occurred within the generally low-nutrient environment. Their location was correlated in part to stabilization of sediments by certain benthic microalgae. These areas may be zones of enhanced nitrogen remineralization, benthic nitrogen f l u e s , and possibly nitrification coupled to denitrification. Comparison of the range of fluxes predicted from ammonification data to the range of measured fluxes showed both positive and negative deviations. Nitrification coupled to denitrification cannot be ruled out as an explanation for measured fluxes which were lower than the production-predicted f l u e s because Eh and pH conditions were within the environmental limits of denitrifying organisms. Loss of nitrogen via denitrification would be an important process to verify in coral reef ecosystems where conservation of nitrogen apparently is otherwise maximized.

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Section: Discussionsupporting

confidence: 68%

Section: Discussionmentioning

confidence: 68%

Section: Introductionmentioning

confidence: 99%

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Ammonium distributions, production, and efflux from backreef sediments, St. Croix, US Virgin Islands

Williams¹,

Yarish²,

Gill³

1985

Mar. Ecol. Prog. Ser.

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“…3). N : P pore-water ratios from nearshore carbonate sediments yield much lighter N : P ratios (Hines and Lyons 1982), probably indicating the more rapid adsorption of Pod3 -onto carbonate grains (Berner 1974). After the pore-water N : P ratio is corrected for the effects of differential diffusion and adsorption (Martens et al 1978;Krom and Berner 1980, 198 1;Froelich et al 1988), the N : P ratio of the organic matter is 20 : 1, yielding a C: N: P of 106 : 3.8 : 0.2.…”

Section: Resultsmentioning

confidence: 99%

Jellyfish Lake, Palau: Regeneration of C, N, Si, and P in anoxic marine lake sediments

Lyons

Lent

Burnett

et al. 1996

Limnology & Oceanography

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Sediment cores from Jellyfish Lake were processed under an inert atmos phcre and the pore waters extracted and analyzed for the following parameters: pH, titration alkalinity (TA), Cl-, H4Si04, POd3-, NH4+, Ca2+, Mg2+, SOd2-, and H2S. Additionally, in one set of pore-water samples (core lo), the 613C of the X0, was also determined. The TA, H4Si04, POd3-, NH;+, and H,S increased with depth in the pore waters above anoxic bottom-water values. H,S values increased to 3.8 PM. In one case, both H,SiO, and POd3-concentrations increased to a maximum value and then decreased with depth, suggesting removal into solid phases. The H,SiO, concentrations are equal to or greater than pore-water values observed in sediments underlying upwelling areas. Pod3 -concentrations are, in general, lower than pore-water values from terrigenous nearshore areas but higher than nearshore carbonate pore-water values from Florida Bay or Bermuda. The Ca2+, Cl-, and Mg2+ : Cl-ratios show slight decreases in the top 15-20 cm, suggesting that authigenic carbonate may be forming. This suggestion is supported by the fact that the pore waters are saturated with respect to CaCO, due to the very high TAs. The 613C measurements of the pore-water X0, are from a shorter core. These measurements reach their most negative concentration at 72 cm and tilen become slightly heavier. This change is accompanied by a decrease in TA, suggesting the onset of methanogenesis at this location in this core.l Present address:

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“…Summertime water column stratification typically results in seasonal hypoxia and anoxia in the bottommost 2-m depth of Devil's Hole (e.g., Coull, 1969;Beers and Herman, 1969;Thorstenson and Mackenzie, 1974;Brown, 1978Brown, , 1980Andersson et al, 2007;Parsons et al, 2015). As such, Devil's Hole has been the focus of studies of CaCO 3 sediment dissolution (e.g., Berner, 1966;Lyons et al, 1974;Balzer and Wefer, 1981;Hines and Lyons, 1982;Andersson et al, 2007), nitrogen cycling (Brown, 1981), trace-element cycling (Jickells and Knap, 1984), and microbial community changes (Coull, 1969;Parsons et al, 2015). The sediment and benthos of Harrington Sound exhibits zonation (Neumann, 1965) with a shallow sandy zone (0-10 m), a stony coral zone of Oculina sp.…”

Section: Sampling Locationsmentioning

confidence: 99%

Twenty Years of Marine Carbon Cycle Observations at Devils Hole Bermuda Provide Insights into Seasonal Hypoxia, Coral Reef Calcification, and Ocean Acidification

Bates

2017

Front. Mar. Sci.

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Open-ocean observations have revealed gradual changes in seawater carbon dioxide (CO 2 ) chemistry resulting from uptake of atmospheric CO 2 and ocean acidification (OA), but, with few long-term records (>5 years) of the coastal ocean that can reveal the pace and direction of environmental change. In this paper, observations collected from 1996 to 2016 at Harrington Sound, Bermuda, constitute one of the longest time-series of coastal ocean inorganic carbon chemistry. Uniquely, such changes can be placed into the context of contemporaneous offshore changes observed at the nearby Bermuda Atlantic Time-series Study (BATS) site. Onshore, surface dissolved inorganic carbon (DIC) and partial pressure of CO 2 (pCO 2 ; >10% change per decade) have increased and OA indicators such as pH and calcium carbonate (CaCO 3 ) saturation state ( ) decreased from 1996 to 2016 at a rate of two to three times that observed offshore at BATS. Such changes, combined with reduction of total alkalinity over time, reveal a complex interplay of biogeochemical processes influencing Bermuda reef metabolism, including net ecosystem production (NEP = gross primary production-autotrophic and heterotrophic respiration) and net ecosystem calcification (NEC = gross calcification-gross CaCO 3 dissolution). These long-term data show a seasonal shift between wintertime net heterotrophy and summertime net autotrophy for the entire Bermuda reef system. Over annual time-scales, the Bermuda reef system does not appear to be in trophic balance, but rather slightly net heterotrophic. In addition, the reef system is net accretive (i.e., gross calcification > gross CaCO 3 dissolution), but there were occasional periods when the entire reef system appears to transiently shift to net dissolution. A previous 5-year study of the Bermuda reef suggested that net calcification and net heterotrophy have both increased. Over the past 20 years, rates of net calcification and net heterotrophy determined for the Bermuda reef system have increased by ∼30%, most likely due to increased coral nutrition occurring in concert with increased offshore productivity in the surrounding subtropical North Atlantic Ocean. Importantly, this long-term study reveals that other environmental factors (such as coral feeding) can mitigate against the effects of ocean acidification on coral reef calcification, at least over the past couple of decades.

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Biogeochemistry of Nearshore Bermuda Sediments. I. Sulfate Reduction Rates and Nutrient Generation

Cited by 69 publications

References 22 publications

Ammonium distributions, production, and efflux from backreef sediments, St. Croix, US Virgin Islands

Ammonium distributions, production, and efflux from backreef sediments, St. Croix, US Virgin Islands

Jellyfish Lake, Palau: Regeneration of C, N, Si, and P in anoxic marine lake sediments

Twenty Years of Marine Carbon Cycle Observations at Devils Hole Bermuda Provide Insights into Seasonal Hypoxia, Coral Reef Calcification, and Ocean Acidification

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