ICES CM 2002/L:01 ACQUIRING MARINE LIFE DATA WHILE EXPERIMENTALLY ASSESSING ENVIRONMENTAL IMPACT OF SIMULATED MINING IN THE DEEP SEA Teresa Radziejewska1* and Ryszard Kotliński2,3 1Department of Oceanography, Agricultural University, ul. Kazimierza Królewicza 4, 71-550 Szczecin, Poland 2Interoceanmetal Joint Organization, ul. Cyryla i Metodego 9, 71-541 Szczecin, Poland 3Technical University of Szczecin, al.Piastów 41, 71-065 Szczecin, Poland ABSTRACT The deep-sea realm is one of the least-known oceanic areas on Earth, yet plans are underway to commercially develop its mineral resources. It is mandatory, before such plans are implemented, to perform appropriate environmental impact assessments involving, i.a., field experiments in which exploitation-oriented activities (e.g., mining) are simulated. Experiments aimed at assessing environmental impacts of deep-sea mining can be, and are, a largely untapped source of data on composition, abundance, and distribution of various ecological groupings of organisms. Here we describe acquisition and type of data on abyssal mega- and meiobenthos, obtained during the 1995-1997 Interoceanmetal Benthic Impact Experiment (IOM BIE). The experiment was aimed at assessing environmental effects of a small-scale abyssal seafloor disturbance simulating that created by polymetallic nodule mining in the Clarion Clipperton Fracture Zone (NE Pacific). The marine life data were derived from analyses of visual imagery (videotapes and underwater photography) and deep- sea sediment cores. The resultant census of organisms provided information on the occurrence of a number of higher-level megafaunal and meiobenthic taxa as well as on more finely- resolved (genus level) assemblages of meiobenthic nematodes (Nematoda) and harpacticoids (Copepoda Harpacticoida). The data, particularly those pertaining to the meiobenthos, lend further support to the notion of high deep sea biodiversity. Key words: deep sea, marine life census, biodiversity, megafauna, meiobenthos, environmental impact ________________________________________________________________ *present address: Department of Palaeooceanology, University of Szczecin, ul. Wąska 13, 71-415 Szczecin, Poland 1 INTRODUCTION Evidence, accumulating since the 1872 - 1876 HMS “Challenger” expedition results were first published (Thomson, 1878), has highlighted the enormous richness of the deep-sea life (Grassle and Maciolek, 1992). However, the census of the deep-sea life is far from complete. In spite of great progress achieved in the study of abyssal communities since the “Challenger” times, the research is still hampered by the sheer vastness of the deep sea bottom, difficult access, and high costs involved (Gage, 1996). For this reason, it has been advocated to supplement the collection of data on deep-sea diversity by acquiring relevant information during other types of research effort, including experimental testing of effects of medium- scale disturbances (Gage, 1996). The deep seabed is known to harbour vast deposits of valuable minerals (Kotliński, 1999). Plans are underway to commercially develop at least some of those resources, polymetallic nodules featuring prominently among them (Morgan, 2000). According to current international regulations (ISBA, 2001), commercial exploitation of polymetallic nodules in open sea (beyond national jurisdictions) has to be preceded by the assessment of impact such an activity will have on the environment and communities it is likely to affect. As the development of the world’s oceanic polymetallic nodule deposits is imminent, albeit removed in time, there has been a number of attempts to assess potential environmental consequences of nodule mining (ISOPE, 2002). Those attempts involved field experiments, known under acronyms such as DISCOL (Thiel et al., 2001), BIE (Trueblood and Ozturgut, 1997), JET (Fukushima 1995), IOM BIE (Kotlinski and Stoyanova, 1998), and INDEX (Sharma, 2001) during which the sediment was disturbed in a manner that would approximate that accompanying a mining operation. All of those experiments entailed a more or less in-depth study of animal communities in the areas affected. Although most of the faunistic data have not been formally published yet, they constitute a rich, largely untapped source of information. In this work, we are describing the type of marine life census data collected during research related to the Interoceanmetal Benthic Impact Experiment (IOM BIE), carried out within 1994 – 1997. BACKGROUND INFORMATION: INTEROCEANMETAL JOINT ORGANIZATION, ITS CLAIM AREA, AND THE BENTHIC IMPACT EXPERIMENT (IOM BIE) Interoceanmetal Joint Organization (IOM), an intergovernmental consortium, was set up in 1987 for the purpose of preparing commercial development of polymetallic nodule deposits from a 75,000 km2 seafloor claim area in the Pacific’s Clarion-Clipperton Fracture Zone (Kotliński, 1998). In 2001, the organization, at present supported by 6 states (Bulgaria, Cuba, the Czech Republic, Poland, Russian Federation, and Slovakia), concluded a contract with the International Seabed Authority (ISBA) to carry out extensive exploration of the claim area (Fig. 1); upon conclusion of the contract, IOM has become, to use the ISBA terminology, a contractor. The IOM area (Kotliński, 1998) is situated in the eastern part of the Pacific’s Clarion- Clipperton Fracture Zone (CCFZ) (Fig. 1), within a large sub-latitudinal polymetallic ore field extending over about 4200 km in length and about 300-900 km in width. The field covers a total of about 2 million km2 area of the abyssal accumulation plain within the Pacific’s North- 2 Fig. 1. A, IOM claim area in the Clarion-Clipperton Fracture Zone (NE Pacific); B, phototransects performed in 1994-1997 around and across the IOM BIE test site (rectangle); C, meiobenthos sampling sites in nodule-free IOM BIE test site (rectangle) and on nodule- covered bottom (solid circles) Eastern Basin. The average ocean depth in the area increases from about 4000 m in the east to about 5400 m in the west, in line with the westward sloping of the ocean floor. The abyssal plain in the area features a number of elongated valleys, terraces, and abyssal hills. In addition, the seafloor displays topographic structures of volcanic origin. The uppermost semi- liquid sediment layer consists of elluvial-deluvial clays and oozes with montmorillonite and chlorite and siliceous radiolarian oozes (Andreev and Gramberg, 1998; Kotliński, 1999). Polymetallic nodules, covering the sea floor (Fig. 2) at abundances frequently exceeding 10 kg m-2, are partially embedded in the semiliquid surficial sediment (Andreev and Gramberg, 1998; Kotliński, 1999). 3 Fig. 2. IOM area in the Clarion-Clipperton Fracture Zone (NE Pacific): a fish (Coryphaenoides sp.) hovering above a polymetallic nodule-covered seafloor Within the extensive polymetallic nodule field, nodule-free patches of various size are occasionally seen. One of such patches, 1.5 km x 2.0 km in dimensions, was selected as the site of the IOM Benthic Impact Experiment (IOM BIE) (Kotliński et al., 1996; Kotliński and Stoyanova, 1998; Tkatchenko and Radziejewska, 1998; Radziejewska, 2002). IOM BIE was carried out in July-August 1995, following preliminary surveys. During the experiment, the seafloor was disturbed with a device the action of which (sediment fluidisation and resuspension in the water column above the bottom) was intended to produce effects similar to those expected from a nodule collector towed on the seabed. The device, known as the Benthic Disturber, was described in detail by Brockett and Richards (1994). The experimental design of IOM BIE, the methods used, and the results were discussed by Kotliński and Stoyanova (1998) and Radziejewska (2002). The test site was revisited for follow-up sampling in April-May 1997 and in June 2000 (Radziejewska, 2002; Radziejewska et al., 2001 b). 4 DATA ACQUISITION Abyssal megafauna: phototransects Data for the study of the abyssal megafauna, i.e., the animals visible and identifiable on underwater photographs and video images (Bluhm, 1994), were collected during cruises of RVs YUZHMORGEOLOGIYA and PROFESSOR LOGACHEV in October 1994, July 1995, and April 1997 from a total of 14 phototransects (Fig. 1 B), extending from 1.19 to 10.3 km in length and laid out over both nodule-bearing and nodule-free areas of the seafloor (Radziejewska and Stoyanova, 2000). The epibenthic megafauna and biogenic traces were studied on photographs taken from the transects with different towed deep-sea camera systems (Tkatchenko and Radziejewska, 1998; Radziejewska and Stoyanova, 2000). A total of 7860 frames, 1439 of them containing images of megafaunal organisms, were examined. The organisms visible on the photographs were identified to major taxa. Details of the analytical techniques applied are given by Radziejewska and Stoyanova (2000). In 2001, an additional series of 13 phototransects was effected, resulting in about 16000 frames taken with a digital camera (A.Parizek, pers.comm.). Analysis of the frames for the purpose of, i.a., megafauna census and distribution assessment, is in progress. Abyssal meiofauna: sediment cores The meiofauna (= meiobenthos), i.e., metazoan invertebrates passing through a 0.500 mm mesh size sieve and retained on a 0.032 mm one (Thiel, 1983), were collected from the IOM BIE test site (Fig. 1 C) in the nodule-free area just before the experimental disturbance and immediately after it in July-August 1995 from the Disturber track area, as well as 22 months and 5 years after