Microhabitat distribution of Smacigastes micheli (Copepoda: Harpacticoida: Tegastidae) from deep‐sea hydrothermal vents at the Mid‐Atlantic Ridge, 37° N (Lucky Strike), with a morphological description of its nauplius

Abstract

Abundant nauplii and copepodid stages attributed to Smacigastes micheli Ivanenko & Defaye (Crustacea: Copepoda: Harpacticoida: Tegastidae) were collected during the MoMARETO cruise (2006) on the Eiffel Tower edifice, the species type locality at the Lucky Strike vent field (37° N) of the Mid‐Atlantic Ridge at a depth of 1698 m. Specimens were sampled within different faunal assemblages dominated by either Bathymodiolus azoricus mussels or Mirocaris fortunata shrimps and the physico‐chemical conditions of their related microhabitats were characterized. A new preparation method for examination of copepod nauplii with confocal microscopy was developed and applied to the specimens. The description of the sixth naupliar stage of S. micheli revealed a number of distinctions from the only known last naupliar stage of the tegastid copepod Tegastes falcatus living associated with a shallow water bryozoan. Morphological features and ecological observations suggest that S. micheli copepods could be feeding on the thick microbial mats that cover different surfaces on the Eiffel Tower edifice. The nauplii, copepodids and adults of S. micheli were found in >80% of the microhabitats sampled. These microhabitats were characterized by temperatures varying from 4.8 to 7.5 °C representing low hydrothermal inputs. Canonical analysis shows that the relative abundances of nauplii and adults of S. micheli were higher at the lower end of the chemical conditions, whereas the abundance of the subadult stages appears to be linked with slightly higher hydrothermal inputs. Whether this distribution is influenced by distinct physiological tolerances or nutritional needs of the different developmental stages is unknown. Total dissolved sulfur was the variable best explaining the distribution of S. micheli on the Eiffel Tower edifice.

First insights into macro- and meiofaunal colonisation patterns on paired wood/slate substrata at Atlantic deep-sea hydrothermal vents

“…Among the known copepod vent taxa, Smacigastes micheli, previously described for the Lucky Strike vent field, probably feeds on microbial mats and detritus (Ivanenko et al, 2012), which might explain its high densities on panels A2-B2 and possibly on B3. Tisbe spp.…”

“…Copepod individuals were dissected under a Leica MZ12 microscope and studied with a Leica DMR compound microscope having bright-field and differential interference contrast optics. The nauplii were studied by applying the "hanging drop method" for light microscopy (see Ivanenko et al, 2012).…”

Five new coexisting species of copepod crustaceans of the genus Spaniomolgus (Poecilostomatoida: Rhynchomolgidae), symbionts of the stony coral Stylophora pistillata (Scleractinia)

“…For confocal microscopy, exoskeletons were individually transferred to distilled water and then stained with Fuchsin (Ivanenko et al 2012; Corgosinho et al 2018). The copepods were inspected using an inverted Nikon A1 confocal laser scanning microscope (CLSM, Nikon Corporation, Tokyo, Japan) at Lomonosov Moscow State University, using a 40× oil immersion objective and lasers with wavelengths of 532 and 640 nm.…”

High-resolution dynamics of a deep-sea hydrothermal mussel assemblage monitored by the EMSO-Açores MoMAR observatory

“…Little information and data on the effects of "moderate" environmental variation on the hydrothermal fauna are available for vent ecosystems. Several studies suggested that there is a strong link between faunal distribution, population dynamics and hydrothermal environmental conditions (Sarrazin et al, 1999, Govenar and Fisher 2007, Cuvelier et al, 2009, Ivanenko et al, 2012, Sen et al, 2013, supporting the idea that the fauna respond quickly to "abiotically challenging" environments (Girguis and Lee, 2006). Modifications in fluid flow may influence resource availability (De Busserolles et al, 2009, Beinart et al, 2012) by inducing changes in microbial production (Guezenec et al, 1998;Sievert et al, 2000) and/or the abundance of symbionts (Halary et al, 2008;Robidart et al, 2011).…”