Variability in benthic biomass and activity beneath the Subtropical Front, Chatham Rise, SW Pacific Ocean

Nodder, Scott D.; Pilditch, Conrad A.; Probert, P. Keith; Hall, Julie

doi:10.1016/s0967-0637(03)00094-3

Cited by 81 publications

(101 citation statements)

References 92 publications

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“…Benthic biomass and activity is generally higher on the southern flank of the Chatham Rise, compared to the crest and northern flank (Nodder et al, 2003(Nodder et al, , 2007Probert and McKnight, 1993), which is somewhat incongruous with the lower POC fluxes suggested by this study and previous sediment trap results (Nodder and Northcote, 2001). Thus, it might be the quality, rather than the quantity, of POC supply to the benthos that has the most influence in structuring seafloor communities in this region (Nodder et al, 2003(Nodder et al, , 2007. 234 Th fluxes at 100 m, (e) 234 Th fluxes at the base of the Ez, and (f) POC fluxes at 100 m. All stations are separated into three water types: low salinity (S < 34.5), mid-salinity (34.5 < S < 34.8), and high salinity (S > 34.8) waters.…”

Section: Poc/ 234 Th Ratios and Poc Export Fluxcontrasting

confidence: 96%

“…Interestingly, at mid-depths of 300-600 m, a deficit of total 234 Th was found in waters on both sides of the Chatham Rise crest. This observation may reflect the horizontal transport of the re-suspended particles along the Chatham Rise flanks, consistent with the near-bottom increases in particle fluxes from sediment trap (Nodder, 1997;Nodder and Northcote, 2001) and benthic studies (Nodder et al, 2007) in the area.…”

Section: Meridional Distribution Of 234 Thsupporting

confidence: 66%

“…Nodder (1997) used free-floating cylindrical sediment traps in the vicinity of the STF showing that the POC flux was less than 3 mmol C m −2 d −1 , which is in the same order of magnitude as that found in low export oligotrophic oceans. Indirect evidence from benthic studies, however, indicates that organic fluxes are enhanced on the crest and southern flank of the Chatham Rise (Probert and McKnight, 1993;Nodder et al, 2003). It is thus clear that information on the spatial variation of POC export within the STF is required if we are to evaluate whether the enhanced primary production in the frontal zone also leads to enhanced export production.…”

Section: K Zhou Et Al: Insignificant Enhancement Of Export Flux In mentioning

confidence: 99%

“…The average POC concentration in the upper 100 m was 3.9 µmol C l −1 in this water type, compared to 2.4 µmol C l −1 and 2.6 µmol C l −1 in high and low salinity waters, respectively. In a departure from the vertical distribution of Chl-a, POC concentrations were often higher near the bottom of the water column, which may be indicative of near-bottom sediment resuspension (e.g., Nodder, 1997;Nodder et al, 2007).…”

Section: Chl-a Macronutrient and Poc Distributionmentioning

confidence: 99%

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Insignificant enhancement of export flux in the highly productive subtropical front, east of New Zealand: a high resolution study of particle export fluxes based on 234Th: 238U disequilibria

et al. 2012

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Abstract. We evaluated the export fluxes of Particulate Organic Carbon (POC) in the Subtropical Frontal zone (STF) of the SW Pacific sector of the Southern Ocean. The site is characterized by enhanced primary productivity, which has been suggested to be stimulated through so-called natural iron fertilization processes where iron-depleted subantarctic water (SAW) mixes with mesotrophic, iron-replete subtropical water (STW). We adopted the small-volume 234 Th method to achieve the highest possible spatial sampling resolution in austral late autumn-early winter, MayJune, 2008. Inventories of chlorophyll-a, particulate 234 Th and POC observed in the upper 100 m were all elevated in the mid-salinity water type (34.5 < S < 34.8), compared with low salinity waters (S < 34.5) which were of SAW origin with high macronutrients and high (S > 34.8) salinity waters which were of STW origin with low macronutrients. However, Steady-State 234 Th fluxes were similar across the salinity gradient being, 25 ± 0.78 ((1.5 ± 0.047) × 10 3 ) in the mid-salinity, and 29 ± 0.53 ((1.8 ± 0.032)×10 3 ) and 22 ± 1.1 Bq m −2 d −1 ((1.3 ± 0.066) × 10 3 dpm m −2 d −1 ) in the high and low salinity waters respectively. Bottle POC/Th ratios at the depth of 100 m were used to convert 234 Th fluxes into POC export fluxes. The derived POC flux did not appear to be enhanced in mid-salinity waters where the primary productivity was inferred to be the highest at the time of sampling, with a flux of 11 ± 0.45 mmol C m −2 d −1 , compared to 14 ± 0.39 mmol C m −2 d −1 in high salinity waters and 8.5 ± 0.66 mmol C m −2 d −1 in low salinity waters. This study thus implied that natural iron fertilization does not necessarily lead to an enhancement of POC export in STF regions.

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Section: Poc/ 234 Th Ratios and Poc Export Fluxcontrasting

confidence: 96%

Section: Meridional Distribution Of 234 Thsupporting

confidence: 66%

Section: K Zhou Et Al: Insignificant Enhancement Of Export Flux In mentioning

confidence: 99%

Section: Chl-a Macronutrient and Poc Distributionmentioning

confidence: 99%

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Insignificant enhancement of export flux in the highly productive subtropical front, east of New Zealand: a high resolution study of particle export fluxes based on 234Th: 238U disequilibria

et al. 2012

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“…This is demonstrated in studies both in the waters surrounding New Zealand, including the Chatham Rise (e.g. Nodder et al 2003), and in other global locations (e.g. Honjo et al 1995, Beet et al 2001).…”

Section: Links Between Species Richness and Environmentmentioning

confidence: 82%

Variation in demersal fish species richness in the oceans surrounding New Zealand: an analysis using boosted regression trees

Leathwick¹,

Elith²,

Francis³

et al. 2006

Mar. Ecol. Prog. Ser.

496

366

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We analysed relationships between demersal fish species richness, environment and trawl characteristics using an extensive collection of trawl data from the oceans around New Zealand. Analyses were carried out using both generalised additive models and boosted regression trees (sometimes referred to as 'stochastic gradient boosting'). Depth was the single most important environmental predictor of variation in species richness, with highest richness occurring at depths of 900 to 1000 m, and with a broad plateau of moderately high richness between 400 and 1100 m. Richness was higher both in waters with high surface concentrations of chlorophyll a and in zones of mixing of water bodies of contrasting origins. Local variation in temperature was also important, with lower richness occurring in waters that were cooler than expected given their depth. Variables describing trawl length, trawl speed, and cod-end mesh size made a substantial contribution to analysis outcomes, even though functions fitted for trawl distance and cod-end mesh size were constrained to reflect the known performance of trawl gear. Species richness declined with increasing cod-end mesh size and increasing trawl speed, but increased with increasing trawl distance, reaching a plateau once trawl distances exceed about 3 nautical miles. Boosted regression trees provided a powerful analysis tool, giving substantially superior predictive performance to generalized additive models, despite the fitting of interaction terms in the latter.

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Structure of infaunal communities in New Zealand submarine canyons is linked to origins of sediment organic matter

Leduc

Nodder

Rowden

et al. 2020

Limnology & Oceanography

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Submarine canyons can facilitate the transfer of land-derived organic matter to the deep sea. Here, we investigated links between variability in organic matter availability from land and marine sources and infauna communities in two contrasting canyon systems off New Zealand and used stable isotope analyses to identify potential food sources of benthic invertebrates. Kaik oura Canyon, a steep, short canyon close to the shore, was characterized by high food availability and varying proportions of marine-and land-derived organic matter, whereas Hokitika Canyon, a narrow and lower-gradient canyon that extends further from the coast, was characterized by low food availability and mostly land-derived sediment organic matter throughout. Both macrofaunal and meiofaunal abundance and biomass were greater in Kaik oura Canyon than in Hokitika Canyon. Correlation analyses suggested that land-derived organic matter may contribute to increased meiofaunal abundance in Kaik oura Canyon. Carbon and nitrogen isotopic analyses, however, did not provide unequivocal support for the uptake of land-derived material by large benthic invertebrates in Kaik oura Canyon. Infaunal abundance and biomass were low throughout Hokitika Canyon despite similar concentrations of land-derived organic matter in sediments of both canyons, which suggests that variations in marine-derived organic matter inputs is the main driver of community differences among canyons. Refractory vascular plant material by itself may not provide an adequate food supply to infaunal organisms, but may represent a complementary food resource when more labile marine phytodetritus is also readily available.

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Variability in benthic biomass and activity beneath the Subtropical Front, Chatham Rise, SW Pacific Ocean

Cited by 81 publications

References 92 publications

Insignificant enhancement of export flux in the highly productive subtropical front, east of New Zealand: a high resolution study of particle export fluxes based on <sup>234</sup>Th: <sup>238</sup>U disequilibria

Insignificant enhancement of export flux in the highly productive subtropical front, east of New Zealand: a high resolution study of particle export fluxes based on <sup>234</sup>Th: <sup>238</sup>U disequilibria

Variation in demersal fish species richness in the oceans surrounding New Zealand: an analysis using boosted regression trees

Structure of infaunal communities in New Zealand submarine canyons is linked to origins of sediment organic matter

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Variability in benthic biomass and activity beneath the Subtropical Front, Chatham Rise, SW Pacific Ocean

Cited by 81 publications

References 92 publications

Insignificant enhancement of export flux in the highly productive subtropical front, east of New Zealand: a high resolution study of particle export fluxes based on &lt;sup&gt;234&lt;/sup&gt;Th: &lt;sup&gt;238&lt;/sup&gt;U disequilibria

Insignificant enhancement of export flux in the highly productive subtropical front, east of New Zealand: a high resolution study of particle export fluxes based on &lt;sup&gt;234&lt;/sup&gt;Th: &lt;sup&gt;238&lt;/sup&gt;U disequilibria

Variation in demersal fish species richness in the oceans surrounding New Zealand: an analysis using boosted regression trees

Structure of infaunal communities in New Zealand submarine canyons is linked to origins of sediment organic matter

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Product

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Insignificant enhancement of export flux in the highly productive subtropical front, east of New Zealand: a high resolution study of particle export fluxes based on <sup>234</sup>Th: <sup>238</sup>U disequilibria

Insignificant enhancement of export flux in the highly productive subtropical front, east of New Zealand: a high resolution study of particle export fluxes based on <sup>234</sup>Th: <sup>238</sup>U disequilibria