Bacterial growth and the decomposition of particulate organic carbon collected in sediment traps

Organic content and bacterial metabolism in amorphous aggregations of the northern Adriatic Sea

“…Average specific growth rate in bacteria attached to marine snow was not significantly higher than in ambient water bacteria, as has also been reported by others (Alldredge et al 1986;Karner and Herndl 1992). In GEA, however, bacterial growth rates were significantly lower compared to both the surrounding seawater and to marine snow; these results agree with data from particles collected in sediment traps (Ducklow et al 1985). Assuming a C conversion efficiency for bacteria of 50% (Cho and Azam 1988), we calculated a mean C turnover time for marine snow of 55.9 d (SD = 6 1.4; n = 8) and a mean C turnover time for GEA of 120.7 d (SD = 117.6; n = 7).…”

Organic content and bacterial metabolism in amorphous aggregations of the northern Adriatic Sea

“…Average specific growth rate in bacteria attached to marine snow was not significantly higher than in ambient water bacteria, as has also been reported by others (Alldredge et al 1986;Karner and Herndl 1992). In GEA, however, bacterial growth rates were significantly lower compared to both the surrounding seawater and to marine snow; these results agree with data from particles collected in sediment traps (Ducklow et al 1985). Assuming a C conversion efficiency for bacteria of 50% (Cho and Azam 1988), we calculated a mean C turnover time for marine snow of 55.9 d (SD = 6 1.4; n = 8) and a mean C turnover time for GEA of 120.7 d (SD = 117.6; n = 7).…”

Important Contribution of Bacterial Carbon and Nitrogen to Sinking Particle Export

“…These theoretical values were comparable to those estimated for non‐sinking marine DOM and suspended POM (C: ∼25%, N: ∼50%; Kaiser & Benner, 2008; Kawasaki et al., 2011; Tremblay et al., 2015). Importantly, our values were about one order of magnitude higher than the previous cell‐count‐dependent estimates in sinking POC (1%–4%; Ducklow et al., 1985; Turley & Mackie, 1994). Our estimates suggest that bacterial detritus represents a large fraction of the deeply exported organic matter, substantially beyond that indicated by prior quantitative estimates.…”

Impact of bacteria and zooflagellates on the composition of sinking particles: an in situ experiment

“…Furthermore, the extremely high ratios of 3H-RNA:3H-DNA for many of the sediment trap samples suggest that the deep populations may be experiencing unbalanced growth since it is unlikely that the RNA : DNA concentration ratio exceeds a value of 10 for any growing microbial population . Similar results based on 3H-thymidine and 3H-adenine incubations of trap-collected material (1075 m) from the Middle Atlantic Bight are reported in Ducklow et al (1985). In this regard, microorganisms associated with sediment trap-collected particles appear to be similar to microbial assemblages sampled from surface sediments (Craven & Karl 1985).…”

Organic content and bacterial metabolism in amorphous aggregations of the northern Adriatic Sea

“…Average specific growth rate in bacteria attached to marine snow was not significantly higher than in ambient water bacteria, as has also been reported by others (Alldredge et al 1986;Karner and Herndl 1992). In GEA, however, bacterial growth rates were significantly lower compared to both the surrounding seawater and to marine snow; these results agree with data from particles collected in sediment traps (Ducklow et al 1985). Assuming a C conversion efficiency for bacteria of 50% (Cho and Azam 1988), we calculated a mean C turnover time for marine snow of 55.9 d (SD = 6 1.4; n = 8) and a mean C turnover time for GEA of 120.7 d (SD = 117.6; n = 7).…”

Important Contribution of Bacterial Carbon and Nitrogen to Sinking Particle Export

“…These theoretical values were comparable to those estimated for non‐sinking marine DOM and suspended POM (C: ∼25%, N: ∼50%; Kaiser & Benner, 2008; Kawasaki et al., 2011; Tremblay et al., 2015). Importantly, our values were about one order of magnitude higher than the previous cell‐count‐dependent estimates in sinking POC (1%–4%; Ducklow et al., 1985; Turley & Mackie, 1994). Our estimates suggest that bacterial detritus represents a large fraction of the deeply exported organic matter, substantially beyond that indicated by prior quantitative estimates.…”

Impact of bacteria and zooflagellates on the composition of sinking particles: an in situ experiment

“…Furthermore, the extremely high ratios of 3H-RNA:3H-DNA for many of the sediment trap samples suggest that the deep populations may be experiencing unbalanced growth since it is unlikely that the RNA : DNA concentration ratio exceeds a value of 10 for any growing microbial population . Similar results based on 3H-thymidine and 3H-adenine incubations of trap-collected material (1075 m) from the Middle Atlantic Bight are reported in Ducklow et al (1985). In this regard, microorganisms associated with sediment trap-collected particles appear to be similar to microbial assemblages sampled from surface sediments (Craven & Karl 1985).…”

Organic content and bacterial metabolism in amorphous aggregations of the northern Adriatic Sea

“…Average specific growth rate in bacteria attached to marine snow was not significantly higher than in ambient water bacteria, as has also been reported by others (Alldredge et al 1986;Karner and Herndl 1992). In GEA, however, bacterial growth rates were significantly lower compared to both the surrounding seawater and to marine snow; these results agree with data from particles collected in sediment traps (Ducklow et al 1985). Assuming a C conversion efficiency for bacteria of 50% (Cho and Azam 1988), we calculated a mean C turnover time for marine snow of 55.9 d (SD = 6 1.4; n = 8) and a mean C turnover time for GEA of 120.7 d (SD = 117.6; n = 7).…”

Important Contribution of Bacterial Carbon and Nitrogen to Sinking Particle Export

“…These theoretical values were comparable to those estimated for non‐sinking marine DOM and suspended POM (C: ∼25%, N: ∼50%; Kaiser & Benner, 2008; Kawasaki et al., 2011; Tremblay et al., 2015). Importantly, our values were about one order of magnitude higher than the previous cell‐count‐dependent estimates in sinking POC (1%–4%; Ducklow et al., 1985; Turley & Mackie, 1994). Our estimates suggest that bacterial detritus represents a large fraction of the deeply exported organic matter, substantially beyond that indicated by prior quantitative estimates.…”

Impact of bacteria and zooflagellates on the composition of sinking particles: an in situ experiment

“…Furthermore, the extremely high ratios of 3H-RNA:3H-DNA for many of the sediment trap samples suggest that the deep populations may be experiencing unbalanced growth since it is unlikely that the RNA : DNA concentration ratio exceeds a value of 10 for any growing microbial population . Similar results based on 3H-thymidine and 3H-adenine incubations of trap-collected material (1075 m) from the Middle Atlantic Bight are reported in Ducklow et al (1985). In this regard, microorganisms associated with sediment trap-collected particles appear to be similar to microbial assemblages sampled from surface sediments (Craven & Karl 1985).…”