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Metazooplankton distribution across the Southern Indian Ocean with emphasis on the role of Larvaceans

View Article: PubMed Central

ABSTRACT

The abundance and depth distribution of metazoans >20 μm were investigated at seven stations across the Southern Indian Ocean (SIO), October–November 2006. Copepod nauplii, copepodites and larvaceans dominated the metazooplankton community. Copepodites were most abundant within Agulhas Current and Southern Ocean waters, decreasing toward subtropical/tropical areas, whereas larvaceans showed the inverse pattern. The fraction <200 μm contained the majority of the zooplankton enumerated, including 81, 23 and 93% of the larvacean, copepodite and nauplii abundances, respectively. The relative abundance of larvaceans compared with copepodites increased from 7 to 44% from South Africa towards Australia. Peak copepodite biomass was observed off South Africa, while larvacean biomass was <1% of the copepodite biomass there, increasing to 6% in tropical waters. Both copepodite and nauplii biomass were positively correlated to total Chl a (P < 0.0001), larvacean biomass was only significantly related to temperature (P = 0.0213). Despite their low biomass, larvacean production was estimated to exceed the copepod production up to five times. It appears that the abundance and role of larvaceans in the SIO has been severely underestimated in previous studies; thus future investigations into the fate of organic matter will remain incomplete if this group is not adequately considered.

No MeSH data available.


(A) Station-specific estimated metazooplankton production assuming a GGE of one third of the ingested material and (B) growth rates estimated by the production to biomass ratio; across the Southern Indian Ocean, October–November 2006.
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FBP002F7: (A) Station-specific estimated metazooplankton production assuming a GGE of one third of the ingested material and (B) growth rates estimated by the production to biomass ratio; across the Southern Indian Ocean, October–November 2006.

Mentions: Calculated copepodite and nauplii production was highest at stations 1–3, while estimated larvacean production peaked at stations 5–7 (Fig. 7A). At stations 1–3, larvacean production was <5% of copepod community productivity, while it was equal at station 4 and 6, and four to five times higher at stations 5 and 7. Estimated larvacean specific growth rates (average 0.8 day−1) were higher than those of copepods (average 0.04 day−1) and nauplii (average 0.07 day−1) across the entire SIO (Fig. 7B).


Metazooplankton distribution across the Southern Indian Ocean with emphasis on the role of Larvaceans
(A) Station-specific estimated metazooplankton production assuming a GGE of one third of the ingested material and (B) growth rates estimated by the production to biomass ratio; across the Southern Indian Ocean, October–November 2006.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2667276&req=5

FBP002F7: (A) Station-specific estimated metazooplankton production assuming a GGE of one third of the ingested material and (B) growth rates estimated by the production to biomass ratio; across the Southern Indian Ocean, October–November 2006.
Mentions: Calculated copepodite and nauplii production was highest at stations 1–3, while estimated larvacean production peaked at stations 5–7 (Fig. 7A). At stations 1–3, larvacean production was <5% of copepod community productivity, while it was equal at station 4 and 6, and four to five times higher at stations 5 and 7. Estimated larvacean specific growth rates (average 0.8 day−1) were higher than those of copepods (average 0.04 day−1) and nauplii (average 0.07 day−1) across the entire SIO (Fig. 7B).

View Article: PubMed Central

ABSTRACT

The abundance and depth distribution of metazoans &gt;20 &mu;m were investigated at seven stations across the Southern Indian Ocean (SIO), October&ndash;November 2006. Copepod nauplii, copepodites and larvaceans dominated the metazooplankton community. Copepodites were most abundant within Agulhas Current and Southern Ocean waters, decreasing toward subtropical/tropical areas, whereas larvaceans showed the inverse pattern. The fraction &lt;200 &mu;m contained the majority of the zooplankton enumerated, including 81, 23 and 93% of the larvacean, copepodite and nauplii abundances, respectively. The relative abundance of larvaceans compared with copepodites increased from 7 to 44% from South Africa towards Australia. Peak copepodite biomass was observed off South Africa, while larvacean biomass was &lt;1% of the copepodite biomass there, increasing to 6% in tropical waters. Both copepodite and nauplii biomass were positively correlated to total Chl a (P &lt; 0.0001), larvacean biomass was only significantly related to temperature (P = 0.0213). Despite their low biomass, larvacean production was estimated to exceed the copepod production up to five times. It appears that the abundance and role of larvaceans in the SIO has been severely underestimated in previous studies; thus future investigations into the fate of organic matter will remain incomplete if this group is not adequately considered.

No MeSH data available.