Page 8 - Shimadzu Journal vol.7 Issue1

Environmental Analysis

Methods
Three species of the lysianassoid amphipods (two Hirondellea sp. and encompassed a depth range from ~7000 m to 10,890 m at the
and Eurythenes gryllus; Fig. 2) were sampled across multiple cruises Challenger Deep, Mariana Trench and four depths were chosen
to the Japan, Izu-Bonin, Mariana, Kermadec, New Hebrides and the within the Kermadec Trench (7014, 7884, 9053 and 9908 m). As
Peru-Chile trenches between 2008 and 2017 (Table 1). These such a total of nine sites were examined.
trenches cover a wide spatial distribution within the Pacific Ocean

Fig. 2 The 3 species of Lysianassoidea amphipods collected from six hadal trenches around the Pacific rim. (A) Hirondellea gigas,
(B) Hirondellea dubia & (C) Eurythenes gryllus.
Table 1 Sampling locations of nine populations of Lysianassoidea amphipods across six Pacific hadal trenches: Japan (JT), Izu-Bonin (IBT), Mariana (MT), New Hebrides
(NHT), Kermadec (KT) and Peru- Chile (PCT). The gear used to collected the amphipods were: HL = Hadal-Lander, versions A, B and C, OBS1 = Obulus lander
version 1, Latis = Latis lander (Jamieson 2015).
Trench Region Depth (m) Date Cruise Latitude Longitude Gear Species
JT NW 7703 30.09.08 KH0803 36.24933 142.81683 HL-A H. gigas
IBT NW 9316 18.03.09 KT0903 27.34983 143.31483 HL-A H. gigas
MT NW 10890 29.01.17 SY1615 11.36683 142.42986 HL-C H. gigas
NHT SW 6948 21.11.13 KAH1310 -20.6485 -168.6138 HL-C H. dubia
KT SW 7014 28.11.11 KAH1109 -32.75958 -177.24091 OBS1 H. dubia
KT SW 7884 29.11.11 KAH1109 -32.61641 -177.35822 Latis H. dubia
KT SW 9053 21.02.12 KAH1202 -31.9785 -177.3885 Latis H. dubia
KT SW 9908 30.11.11 KAH1109 -32.02657 -177.37083 Latis H. dubia
PCT SE 7050 10.09.10 SO209 -17.4245 -73.61683 HL-B E. gryllus

The focal amphipod species were the dominant scavenging species in within the amphipod could be easily disregarded in the unlikely event
their respective trenches . Ten individuals from each of the nine sites they appeared in the hindgut. Upon retrieval from depth, the
[53]
were examined. The samples were collected via small funnel traps (6 amphipods were stored in 70-99% ethanol in transparent plastic jars.
cm diameter by 30 cm length with an opening of ~2.5 cm) that were Preservation of fauna in ethanol does not appear to significantly
[54]
[27]
deployed on various Hadal-Lander vehicles , baited with locally impact or degrade the microplastics .
sourced mackerel wrapped in a mesh to prevent bait consumption Precautionary measures were put in place to prevent any airborne and
that could affect future studies. The mesh was either galvanised steel liquid contamination within the laboratory. Surfaces, glassware and
wire or bright yellow plastic. Furthermore, samples were only taken dissection equipment was rinsed with acetone, followed by a final
from the internal hindgut of the specimen to remove the possibility of rinse with type one ultra-pure water directly before use. To prevent
contamination from substances consumed via the bait, wrap, or from solvent contamination, all liquids were filtered using Whatman No.
[55]
the lander. The ballast release mechanism on the Hadal-Lander 540 filter paper . Laboratory coats and nitrile gloves were worn
featured a potential source of plastic microfibre in the form of a throughout. Dissection and identification occurred within a laminar
Dacron (synthetic polyester; polyethylene terephthalate) line that prior flow hood cabinet (Thorflow EDF600) to restrict airborne
to 2010 was bright green and after 2010 was fluorescent yellow. contamination. Samples were sealed prior to removal from the laminar
These distinct colours meant that any similar coloured fibres found flow hood for digestion. Procedural control blanks, done concurrently

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