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Novel benthic foraminifera are abundant and diverse in an area of the abyssal equatorial Pacific licensed for polymetallic nodule exploration

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ABSTRACT

The benthic biota of the Clarion–Clipperton Zone (CCZ, abyssal eastern equatorial Pacific) is the focus of a major research effort linked to possible future mining of polymetallic nodules. Within the framework of ABYSSLINE, a biological baseline study conducted on behalf of Seabed Resources Development Ltd. in the UK-1 exploration contract area (eastern CCZ, ~4,080 m water depth), we analysed foraminifera (testate protists), including ‘live’ (Rose Bengal stained) and dead tests, in 5 cores (0–1 cm layer, >150-μm fraction) recovered during separate megacorer deployments inside a 30 by 30 km seafloor area. In both categories (live and dead) we distinguished between complete and fragmented specimens. The outstanding feature of these assemblages is the overwhelming predominance of monothalamids, a group often ignored in foraminiferal studies. These single-chambered foraminifera, which include agglutinated tubes, spheres and komokiaceans, represented 79% of 3,607 complete tests, 98% of 1,798 fragments and 76% of the 416 morphospecies (live and dead combined) in our samples. Only 3.1% of monothalamid species and 9.8% of all species in the UK-1 assemblages are scientifically described and many are rare (29% singletons). Our results emphasise how little is known about foraminifera in abyssal areas that may experience major impacts from future mining activities.

No MeSH data available.


Rarefaction curves based on complete live (a) and complete live and dead (b) specimens. Solid black lines are based on actual data; dashed lines are extrapolated curves up to 1,500 specimens for each sample.
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f1: Rarefaction curves based on complete live (a) and complete live and dead (b) specimens. Solid black lines are based on actual data; dashed lines are extrapolated curves up to 1,500 specimens for each sample.

Mentions: The most specious multichambered groups were the hormosinids (29 species), various MAF (22), and trochamminids (12), all of them agglutinated (Table 3). Only 30 species (live and dead) were calcareous; of these, 19 were rotaliids, 5 were lagenids, 5 were miliolids and 1 was a robertinid. Most hormosinids (28 out of 29) and rotaliids (17 out of 19) were represented by complete live specimens, whereas most trochamminids (10 out of 12) and other various MAF (21 out of 22) were represented by complete dead specimens. Only 6 multichambered species (5 hormosinids and 1 MAF) were found as fragments.


Novel benthic foraminifera are abundant and diverse in an area of the abyssal equatorial Pacific licensed for polymetallic nodule exploration
Rarefaction curves based on complete live (a) and complete live and dead (b) specimens. Solid black lines are based on actual data; dashed lines are extrapolated curves up to 1,500 specimens for each sample.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5382569&req=5

f1: Rarefaction curves based on complete live (a) and complete live and dead (b) specimens. Solid black lines are based on actual data; dashed lines are extrapolated curves up to 1,500 specimens for each sample.
Mentions: The most specious multichambered groups were the hormosinids (29 species), various MAF (22), and trochamminids (12), all of them agglutinated (Table 3). Only 30 species (live and dead) were calcareous; of these, 19 were rotaliids, 5 were lagenids, 5 were miliolids and 1 was a robertinid. Most hormosinids (28 out of 29) and rotaliids (17 out of 19) were represented by complete live specimens, whereas most trochamminids (10 out of 12) and other various MAF (21 out of 22) were represented by complete dead specimens. Only 6 multichambered species (5 hormosinids and 1 MAF) were found as fragments.

View Article: PubMed Central - PubMed

ABSTRACT

The benthic biota of the Clarion–Clipperton Zone (CCZ, abyssal eastern equatorial Pacific) is the focus of a major research effort linked to possible future mining of polymetallic nodules. Within the framework of ABYSSLINE, a biological baseline study conducted on behalf of Seabed Resources Development Ltd. in the UK-1 exploration contract area (eastern CCZ, ~4,080 m water depth), we analysed foraminifera (testate protists), including ‘live’ (Rose Bengal stained) and dead tests, in 5 cores (0–1 cm layer, >150-μm fraction) recovered during separate megacorer deployments inside a 30 by 30 km seafloor area. In both categories (live and dead) we distinguished between complete and fragmented specimens. The outstanding feature of these assemblages is the overwhelming predominance of monothalamids, a group often ignored in foraminiferal studies. These single-chambered foraminifera, which include agglutinated tubes, spheres and komokiaceans, represented 79% of 3,607 complete tests, 98% of 1,798 fragments and 76% of the 416 morphospecies (live and dead combined) in our samples. Only 3.1% of monothalamid species and 9.8% of all species in the UK-1 assemblages are scientifically described and many are rare (29% singletons). Our results emphasise how little is known about foraminifera in abyssal areas that may experience major impacts from future mining activities.

No MeSH data available.