Electronic Supplement for Article

Electronic supplement for article:

Caught in the act: An abyssal isopod collected while feeding on Komokiaceae

Torben Riehl, Simon Bober, Ivan Voltski, Marina V. Malyutina, Angelika Brandt

Author affiliations

T. Riehl ([email protected]), Simon Bober, A. Brandt

Zoological Museum, Centre of Natural History (CeNak), University of Hamburg, Martin-Luther-King-Platz 3, 20146 Hamburg, Germany

Ivan Voltski

Department of Geological and Environmental Sciences, Ben-Gurion University of the Negev, P.O. BOX 653, Beer Sheva 84105, Israel

Marina V. Malyutina

A.V. Zhirmunsky Institute of Marine Biology, FEB RAS, 17 Palchevskogo Street, 690041; Far East Federal University, Vladivostok, Russia

Additional Discussion

Many deep-sea organisms from abyssal plain soft sediments, such as isopod crustaceans were initially classified as detritus feeders (Menzies 1962). Later, gut-content analyses revealed tests of hard-shelled Foraminifera and it was suggested that selective feeding on living foraminifers may occur in isopod crustaceans (Menzies 1962; Wolff 1976; Svavarsson et al. 1993; Gudmundsson et al. 2000; Brökeland et al. 2010), suggesting that some isopods prey upon protists, in addition to, or instead of, feeding on detritus. The term for this feeding strategy was coined foraminiferivory (Hickman & Lipps 1983) and was subsequently inferred also by means of fatty-acid and stable- isotope biomarkers that revealed a clear signal of enriched foraminifer fatty acids in selected macro- and megafaunal taxa, and thus suggesting that Foraminifera may be considered a bridge in the energy flow from phytodetritus and sediments to metazoans in the deep sea (Nomaki et al. 2008; Würzberg et al. 2011). Given spatial and temporal variability of POC (particulate organic carbon) supply to the abyss, a certain plasticity of food choice can be expected for the benthos (Sokolova 1972; Jamieson et al. 2012). Besides the isopod crustaceans, further evidence for the importance of Komokiacea and the potentially related Xenophyophoria (Gooday et al. 2007) in deep-sea food webs was reported from stomach contents of deposit-feeding holothurians (Sokolova 1972; Khripounoff & Sibuet 1980). These organisms may thus, besides their role as a bridge in the energy flow, also act as a buffer representing a stock upon which certain macro- and megafauna can graze.

Methods for electronic supplement

During the Vema-TRANSIT (Bathymetry of the Vema-Fracture Zone and Puerto Rico TRench and Abyssal AtlaNtic BiodiverSITy Study) expedition, samples were collected along the Vema Fracture Zone with the German research vessel RV Sonne, station SO237-2-7: 20. December 2014; start of trawl: 10°42.891' N, 25°03.167' W; 5,509 m depth (Devey 2015) with a camera-equipped epibenthic sledge (Brandt et al. 2013). The sediment samples were treated and fixed onboard as described elsewhere (Riehl et al. 2014). After fixation, samples were sorted onboard and targeted isopods were separated individually. From the target taxa, such as Betamorpha cf. profunda (Menzies & George 1972) (Munnopsidae; Zoological Museum Hamburg: ZMH K-45805), first photographs and then tissue samples were taken for DNA barcoding and other studies (work in progress). The other images (Figure 1A, C–E) were taken using a macro-photo setup before dissection of tissue for DNA (Devey 2015): A Canon EOS 600D was used with a Canon MP-E 65mm f/2.8 macro lens featuring 5x magnification. A Canon MT–24EX II macro flash and additional SPEEDLITE 430EX slave flashes were used to illuminate the specimen from laterally in order to create a black background. Glass chips were used to stabilize the object in any desired position. The camera was mounted on a stand with manual precision focusing drive. To avoid unnecessary vibration, the Canon software EOS Utility was used to trigger the camera shutter from a laptop and to directly store images on the personal computer hard drive. Additional photographs were taken with a Leica M125 stereo microscope equipped with an AX Carrier (for parallax correction) and a MC170 HD camera. The Camera was connected to a PC and photographs were directly saved to the internal hard drive using the software Leica Application Suite (LAS) v.4.5.0 (Build 418). Finally, the specimen was first transferred to 100 % Ethanol and then soaked in methyl salicylate (salicylic acid methyl ester) for 3–4 hours to change the refractive index and to be able to look through the cuticle and inside the specimen. The specimen was again photographed in this translucent condition using the Leica M125 as described above as well as a Passport II Imaging System (http://www.duninc.com/passport-ii.html) with the MP-E 65mm f/2.8 macro lens.

References for electronic supplement

Brandt, A., Elsner, N., Brenke, N., Golovan, O., Malyutina, M. V., Riehl, T., Schwabe, E. & Würzberg, L. (2013) Epifauna of the Sea of Japan collected via a new epibenthic sledge equipped with camera and environmental sensor systems. Deep Sea Research Part II: Topical Studies in Oceanography, 86–87, 43–55. Brökeland, W., Guðmundsson, G. & Svavarsson, J. (2010) Diet of four species of deep-sea isopods (Crustacea: Malacostraca: Peracarida) in the South Atlantic and the Southern Ocean. Marine Biology, 157(1), 177–178. Devey, C. W. (Ed.) (2015) RV SONNE Fahrtbericht / Cruise Report SO237 Vema-TRANSIT. Geomar Report, 130 (GEOMAR Report). Gooday, A. J., Cedhagen, T., Kamenskaya, O. E. & Cornelius, N. (2007) The biodiversity and biogeography of komokiaceans and other enigmatic foraminiferan-like protists in the deep Southern Ocean. Deep Sea Research Part II: Topical Studies in Oceanography, 54, 1691– 1719. Gudmundsson, G., von Schmalensee, M. & Svavarsson, J. (2000) Are foraminifers (Protozoa) important food for small isopods (Crustacea) in the deep sea? Deep Sea Research Part I: Oceanographic Research Papers, 47(11), 2093–2109. Hickman, C. S. & Lipps, J. H. (1983) Foraminiferivory; selective ingestion of foraminifera and test alterations produced by the neogastropod Olivella. The Journal of Foraminiferal Research, 13(2), 108–114. Jamieson, A. J., Fujii, T. & Priede, I. G. (2012) Locomotory activity and feeding strategy of the hadal munnopsid isopod Rectisura cf. herculea (Crustacea: Asellota) in the Japan Trench. The Journal of Experimental Biology, 215(17), 3010–3017. Khripounoff, A. & Sibuet, M. (1980) La nutrition d’echinodermes abyssaux I. Alimentation des holothuries. Marine Biology, 60(1), 17–26. Menzies, R. J. (1962) On the food and feeding habits of abyssal organisms as exemplified by the Isopoda. Internationale Revue der gesamten Hydrobiologie und Hydrographie, 47(3), 339– 358. Nomaki, H., Ogawa, N. O., Ohkouchi, N., Suga, H., Toyofuku, T., Shimanaga, M., Nakatsuka, T. & Kitazato, H. (2008) Benthic foraminifera as trophic links between phytodetritus and benthic metazoans: carbon and nitrogen isotopic evidence. Marine Ecology Progress Series, 357, 153–164. Riehl, T., Brenke, N., Brix, S., Driskell, A., Kaiser, S. & Brandt, A. (2014) Field and laboratory methods for DNA barcoding and molecular-systematic studies on deep-sea isopod crustaceans. Polish Polar Research, 35(2), 205–226. Sokolova, M. N. (1972) Trophic structure of deep-sea macrobenthos. Marine Biology, 16(1), 1–12. Svavarsson, J., Gudmundsson, G. & Brattegard, T. (1993) Feeding by asellote isopods (Crustacea) on foraminifers (Protozoa) in the deep sea. Deep Sea Research Part I: Oceanographic Research, 40(6), 1225–1239. Wolff, T. (1976) Utilization of seagrass in the deep sea. Aquatic Botany, 2(0), 161–174. Würzberg, L., Peters, J. & Brandt, A. (2011) Fatty acid patterns of Southern Ocean shelf and deep sea peracarid crustaceans and a possible food source, foraminiferans. Deep Sea Research Part II: Topical Studies in Oceanography, 58(19–20), 2027–2035.