Adult life strategy affects distribution patterns in abyssal isopods – implications for conservation in Pacific nodule areas

Abstract

<p><strong>Abstract.</strong> Aim of our study is to gain a better knowledge about the isopod crustacean fauna of the abyssal Clarion Clipperton Fracture Zone (CCZ) located in the central Pacific Ocean. In total, we examined 22 EBS samples taken at 6 abyssal areas in the central pacific manganese nodule area (CCZ and DISCOL). The dataset comprised 619 specimens belonging to 187 species of four different isopod families: 91 species (48.6 % of total) belonging to Munnopsidae, 63 (33.6 %) to Desmosomatidae, 24 (12.8 %) to Haploniscidae and 9 (4.8 %) to Macrostylidae. The total number of species found was relatively similar between sites ranging from 38 (German Contractor area) to 50 species (French contractor area). 68 species were represented by singeletons. The ranges of distribution differ between families. In total 77 % of the species were recorded in a single area (and thus being unique for this specific area), 13.9 % in 2 areas, 5.3 % in 3 areas, 2.6 % in 4 areas and 1 % in 5 areas. The proportion of species present in a single area increased in this sequence: Munnopsidae (75.8 %), Desmosomatidae (77.7 %) and Haploniscidae (83 %). A total of 6 (66.6 %) out of 9 species of Macrostylidae was recorded in a single area contrasted by the most common species being from this family, Macrostylidae_<i>Macrostylis</i>_M05 with 46 specimens (present in all areas besides DISCOL) followed by several species of Munnopsidae with 10 or more specimens in the dataset. The CCZ areas show the highest number of shared species. Generally, the high diversity in each area is reflected by a low similarity between sampling areas. The rarefraction curves indicate that species richness is similar between areas, but the real number of species is still not sampled. The most distant areas from the central CCZ, the APEI3 and DISCOL, are the most different.</p>

Ophiotholia (Echinodermata: Ophiuroidea): A little-known deep-sea genus present in polymetallic nodule fields with the description of a new species

“…Understanding the diversity of seafloor habitats and the associated fauna is critical to making informed decisions about deep-sea conservation (Brix et al, 2019;McQuaid et al, 2020;Jones et al, 2021;Washburn et al, 2021). In the CCZ, the possible extraction of the abundant and valuable nodules could not only result in loss of substratum but will also result in seabed upheaval and possible biodiversity loss, and perhaps an ongoing effect on the (Ratnasingham and Hebert, 2013) local food web (Levin et al, 2016;Niner et al, 2018;Brix et al, 2019;Simon-Lledóet al, 2019a; (E-G). ab, abradial; ASA, arm spine articulation; dis, distal; PSA, parasol spine articulation.…”

Comparative reproductive biology of deep-sea ophiuroids inhabiting polymetallic-nodule fields in the Clarion-Clipperton Fracture Zone

“…Recent studies that have sought to describe the benthic fauna that typify the CCZ have also revealed extraordinarily high taxonomic diversity across representatives from all Domains of Life (e.g. Amon et al, 2016; De Smet et al, 2017; Shulse et al, 2017; Wilson, 2017; Hauquier et al, 2018; Goineau and Gooday, 2019; Brix et al, 2020; Christodoulou et al, 2020), making the CCZ of critical importance for biodiversity conservation. In many of these studies, data (e.g.…”

“…species-abundance curves) strongly suggest that many – arguably most – species remain unaccounted for, with high species turnover over relatively short spatial scales even in groups that are brooders like Isopoda (e.g. Wilson, 2017, Brix et al, 2020). Remoteness of habitat and spatial variability in species composition of this sort present challenges for performing robust ecological studies, as evidenced by the scarcity of ecologically meaningful data available for even the most conspicuous ‘common’ epifaunal species in the CCZ (Danovaro et al, 2017), including many echinoderm species (Amon et al, 2016).…”