A REPORT ON THE CZECHOSLOVAK BIOLOGICAL DIVING EXPEDITION ARCTIC92"

Transcription

1 Zdenek Óuriś Institute of Industrial Landscape Ecology, Ostrava, Czech Republic XX Polar Symposium Lublin, 1993 A REPORT ON THE CZECHOSLOVAK BIOLOGICAL DIVING EXPEDITION ARCTIC92" In the summer of 1992, the Czechoslovak Biological Diving Expedition took part in the international ecological campaign to southern Spitsbergen aboard the Polish research vessel Oceania. This expedition was organized together with Polish specialists from the Institute of Oceanology, Polish Academy of Sciences, Sopot, and prepared with help of the Coordinative Committee for European Arctic Ecological Research. The scuba-diving method was applied to collect benthic organisms and to photo-sample benthic biocenoses off Bolscheoya Island, Tusenoyane (i.e. the Thousand Islands, off southern Edgeoya), south-eastern Svalbard. The island is known for a large group of walruses. Questions on the distribution of benthic fauna as a potential feeding ground for walruses were the focus of the present expedition undertaken as a part of a joint effort of the Arctic Ecology Group (Institute of Oceanology, Sopot) and Norsk Polarinstitutt, Oslo. Together with Czech divers' work, a dredged or bottom-grab material was collected by Polish specialists. The sampled material, environmental measurements, and underwater photos were examined by the common international team. The preliminary results have been published (Węsławski et al., 1992). A study of the decapod crustaceans collected during that campaign was prepared as a special report (Duris, 1993). Specimens (176) of the decapod crustaceans belonging to 6 species were determined in the collected material. That material has allowed us to compare the decapod faunae of the Bellsund region studied during the 1991 expedition (Duris, 1992a, b). Only very poor information on the decapods of the eastern Svalbard may be found in literature in this aspect. The scuba-diving method was used for immediate underwater observations and collections of the material (Tab. 1; Fig. 2 in Duris 1993). Two divings were dedicated to made underwater photos of various characteristics of bottom and benthic biocenoses. Thirty seven dredging stations were also made from the Zodiac boat by Polish research workers. Dredging stations, as well as diving stations, were selected with the use of boat echosonder. For quantitative scuba-diving samples a modified benthometer with 0.5 mesh 485

2 size sack, and limiting 0.25 m 2 of the bottom, was developed. The benthometer consists of 30 cm high cylindrical frame with 2mm mesh size wall with removable 0.5 mm mesh size sack attached to special frame on one side of the wall and open inside to the cylinder. The lower border of the benthometer limiting the bottom area 0.25 m 2 is provided with 5 cm high triangular teeth. At least two divers are necessary to operate with the benthometer (Fig. 1). The first diver places the apparatus at a selected point and presses it down to the bottom together with short,,there-and-back" movements in a circle. A sampled area 0.25 m 2 is determined by this way. The mesh wall prevents mobile animals to escape. Large seaweeds and animals are removed to the mesh sack or to the plastic bag of the second diver, and larger stones without organisms are also removed. Digging to the bottom inside the benthometer torgether with turning and scraping stones results in rising plant and animal benthic organisms up to the water which, following a local current, moves through the mesh wall. Organism then drift, or they actively move, along the wall to the mesh sack. The sack may be then replaced with another one, and the second diver can take the sack with the collected sample to the boat. An anchor rope may be used by divers for underwater orientation. The quantitative samples were taken at five selected stations, three samples at each of them. PRELIMINARY DATA ON MAIN ECOSYSTEMS AROUND BÓLSCHE0YA ISL., SPITSBERGEN, BARENTS SEA (based on scubc-driving works and observations). For the localities see Fig. 2 in Ouriś, 1993, this volume. AUGUST 8, 1992 Divers: Z. Duris and J. Śabacky Locality: Coastal waters just opposite the temporary living base, northern coast Sample: A" Method/Aim: Checking the diving equipment and underwater photo, first observations Start/time: 16.40/30 min Descriptions: Rocky shore, depths 5-7 m just near the shore, large rocky blocks and stones. Benthic seaweeds Fucus and Laminaria on sheltered places, exposed sides of bottom devoid of seaweed vegetation (effect of flowing ices). Benthic fauna under stones numerous specimens of amphipod crustaceans, caridean shrimps Eualus gaimardii gibba. Two specimens of polar cod observed near stones, about 4 and 15 cm long. 486

3 AUGUST 9, 1992 Divers: Z. Duris and J. Szymonik Locality: Profile Nord Base on Island" Sample: В" Method/Aim: Photo sampling of bottom using scaled frame Start/time: 15.50/75 min Descriptions: Three photos made at depth 25 m: sandy-gravel bottom covered with scattered seaweeds Alaria esculenta and Laminaria saccharina keeping on solitary small stones. Flat-tallomed rhodophyta and compact colonies of hydroid polyps and bryozoans present. Dominant benthic invertebrate large holthurian (Cucumariafrondosa) feeding on seston. Frequently observed large specimens of crangonid shrimp Sclerocrangon boreas, gastropods Buccinum and Natica cf. clausa, spirale-shaped egg-cases of gastropod Natica. Very numerous shells of bivalve Mya truncata, empty, often crushed, but living specimens not found. At some locations shallow pits, about half meter in diameter, were observed on bottom, some with small greenish, thin-shelled bivalves uncovered from the bottom (a result of macroalgae pulled out by strong current together with their stone, or of walrus feeding?). A group of walruses were observed from the boat during this time diving about 50 m far. Depth 24 m (about 100 m back in a direction to the island): the same ecosystem, no photos. Depth 24 m (about 200 m back in a direction to the island): 1 photo large crab Ну as araneus among bases of macroalgae. The alaria-holothuria" ecosystem similar to the one described above. Depth 22.5 m (about 200 m back to the island): the same ecosystem. No photos. AUGUST 10, 1992 Divers: Z. Duris and J. Szymonik Locality: Profile East Islad" Sample: С" Method/Aim: Photo sampling of bottom onfixed distance using scaled frame Start/time: 16.50/90 min Descriptions: Depth 23 m: 6 photos. Several meters wide path of Alaria-Laminaria occupies very shallow channel lying in the direction of strong tidal current. The channel is surrounded by fields of a sandy-gravel bottom without macroalgae, and also without holothurians. Small gastropods (.Margarites?), amphipod crustaceans and reddish ophiurs are present. Several siphones of small bivalves were observed. A seaweed path is associated with fauna and flora as in the previous locality: rhodophyta, numerous holothurians, colonies of Hydrozoa and Bryozoa, several specimens of shrimp Sclerocrangon boreas. Crab Hyas araneus and a narrow, finger-like sponge were observed. 487

4 Depth 13.5 m: 3 photos. Flat sandy-gravel bottom, occasionally low barrier with larger stones. Patches of seaweeds with usual associates. On stones barnacles (Balanusl), and cap-like sponge. Stream. Depth 10 m: 3 photos. Slightly deeper channels lying along tidal current direction and provided with Alaria and Laminaria and associates; low rocky and stony barrier covered on sides by compact crustae of high and narrow cirripedian barnacles (Balanusl), a lot of their shells lie crushed on bottom near stones. Small gastropods Margarites, unidentified fish. Strong current. Depth m (about 70 m off shore). Rocky monolith, various depths, frequent blocks of rock. Exposed sites without algal cover (result of icebergs wiping effect), sheltered places densely covered with Fucus and Laminaria. Spots of calcareous algae and colonies of cirripedian barnacles on free surfaces of rock. Very strong current. AUGUST 11, 1992 Divers: Z. Duris and J. Sabacky Locality: Profile South Island" Sample: D" Start/time: 19.00/15 min Descriptions: Depth 15 m: Strong current. Flat and hard gravel bottom. Numerous Laminaria and Alaria originally from another place but dragged here in current together with stones kept by rhizoids. Only the seaweeds were taken, no significant macroinvertebrates were caught into the net of the benthometer after loosening bottom surface. Divers: Z. Duris and J. Sabacky Locality: Profile East Island" Sample: E" Start/time: 19.30/35 min Descriptions: Depth 23 m. 3 samples were taken together with upper layer of bottom material. Gravel, crushed shells. Scattered cover of Laminaria and Alaria. Gastropods Margarites, Buccinum, egg cases of Natica, small specimens of Mya truncata, numerous amphipods, shrimp Sclerocrangon boreas, rhodophyta. AUGUST 13, 1992 Divers: Z. Duris and J. Sabacky Locality: Profile North Island" Sample: F" 488

5 Start/time: 17.30/35 min Descriptions: Depth 24 m. 3 samples taken together with upper layer of bottom material. The bottom and the seaweed-holothurian ecosystem as described above for August 9. Strong current. Several large shrimps Sclerocrangon boreas. Two samples inside the seaweed-holothurian biotope, the third sample outside through dragging of divers as well as of anchored boat away by current. Locality: Profile North Island" Sample: G" Start/time: 19.30/15 min Descriptions: Depth 15 m. 3 samples taken together with upper layer of bottom material. Very strong current, dragging all the sampling equipment, divers, anchored boat, as well as laminarian seaweeds pulled out from bottom together with their stones. Those three samples were taken on a distance between the walrus bay" and our temporary living base on the island (about m) through the current. AUGUST 14, 1992 Divers: Z. Duris and J. Szymonik Locality: Profile North-West Island" [150 ] Sample: H" Start/time: 19.30/30 min Descriptions: Depth 23 m. 3 samples taken (J. Szymonik collected) together with upper layer of bottom material. Gravel bottom occupied with Alaria esculenta and Laminaria saccharina associated with holothurians and other organisms mentioned above for similar biotops. Crab Hyas araneus also observed. MARINE BENTHIC ECOSYSTEMS AROUND BÓLSCHE0YA ISLAND (based on SCUBA-diving observations) Two main benthic ecosystems associated with the two main types of marine bottom, the coastal rocky reefs, and flat gravel bottom, may be found off Bolscheoya Island, Spitsbergen, Barents Sea. The rocky shore with narrow underwater reefs surrounds the island down to dephs of 5-8 m. Along its south-eastern coast, the rocky formations extend themselves to the sea into a broad underwater plateau of rocky blocks at dephs of 4-6 m. The benthic ecosystem on such type of bottom may be affected by salinity 489

6 changes from iceberg discharges during summer, by tidal changes followed with strong currents and mechanical scraping effect under Arctic icebergs. So, when sheltered sites and places of such bottom are densely covered by seaweeds of the genera Fucus and Laminaria, the exposed sites of rock and large stones are usually devoid of any seaweed or invertebrate cover. Rocky and stone reefs are occupied also with red and calcareous algae, attached invertebrates are represented by cirripedian barnacles, colonies of hydropolyps and bryozoans, and sponges. Small fish, including the polar cod, and movable invertebrates, such as amphipod crustaceans and shrimps Eualus gaimardi gibba, look for their shelters near and under stones and seaweed cover. The main area surrounding for several miles of Bolscheoya is occupied by extended flat sandy gravel bottom withfields of Laminaria and Alaria seaweeds. Within depths of about 8-20 m the seaweedfields usually possess a form of long paths corresponding to main tidal currents. The paths are surrounded by more or less extended areas of fine or more rough gravel, devoid of seaweeds occupying about 50-70% of the bottom. At deeper waters, down to 20 m, the seaweed fields more widely cover the bottom, and less depending on currents, they have more irregular configurations. In all, there are not extended ecosystems or biotic zones distinctly distributed by depths, but only irregular mosaic pattern of seaweed fields and gravel deserts". The seaweed biotope, usually situated in shallow channels or bottom depressions in shallower waters, is inhabited by various plant and animal forms of marine organisms. Together with dominant seaweeds Laminaria saccharina and Alaria esculenta, the dominant invertebrate is a large holothurian Cucumaria frondosa. The seaweeds named here are also followed with much smaller red algae as well as colonies of attached invertebrates, sponges, hydroids and bryozoans using also solitary small stones of seaweed rhizoids as a substrate. A morefine sand-gravel substrate is inhabited by invertebrate infauna consisting mainly of small forms polychaete worms, bivalve molluscs (Yoldial). Numerous empty, often also broken, shells of My a truncata cover the bottom in this biotope. Amphipod crustaceans as well as large decapods, crab Hyas araneus and shrimp Sclerocrangon boreas are associated with the seaweed-holothurian biotope. Gastropods Buccinum sp., Natica cf. clausa, Margarites sp., and other small gastropod molluscs. Small reddish ophiurans may also be often found here. Also rather abundant is the occurrence of flat spiral-shaped egg-cases of gastropod Natica lying on bottom. The areas without seaweed cover is usually very poor with respect to associated invertebrates. Low barriers with stones exposed to currents may be present. Only small amphipods, gastropods and bivalve molluscs are occasionally observed there, but they also may absent because thefine or more rough gravel bottom is rather hard. Especially in shallower depths, the bottom material is more distinctly sorted and removed by strong tidal currents. As a result of 490

7 immediate diving observations, we can state that Laminaria or Alaria talloms caught frequently in such areas by usual sampling methods with dredges or grabs may not be considered as indicators of a relatively rich seaweed-holothurian biotope at an actual location. The plants come originally from another place but were dragged here after being pulled out by strong current together with stones keeping them on'the bottom. An absence of associated fauna could now indicate such undersea deserts" recovered by seaweeds with fluctuating stony anchors". This phenomenon observed may point to a source of errors and higher deviations during ecological evaluations of similar benthic ecosystems using standard methods. REMARKS Immediate observations on the character of main shallow-water marine benthic ecosystems using SCUBA-divers, or from a boat using remote underwater photo or video-camera, may allow more effective evaluation of results than standard sampling methods. In some cases, divers may also take quantitative samples of biotopes on hard or other problematic substrates where standard methods appear to be rather uneffective. As an aid to discovery of main ecosystems in any shallow water area, we can recommend an application of a series of short but numerous individual divings in distinct profiles using small boats with echosonda and with a possibility to fast board fully equipped divers from water. Such dives may be used for classification of an actual location and for an evaluation of percentage of main ecosystems in an investigated area. Ecological evaluation of the area can be then done based also on shorter series of quantitative samples from main ecosystems. The method may be useful for short-time field research. ACKNOWLEDGEMENTS I am grateful to my friends and colleagues, dr J. Wiktor and dr M. Zajączkowski (Institute of Oceanology, Sopot, Poland), and Mr. J. Szymonik and Mr. J. Sabacky (Czech diver clubs of Ostrava), for their help and assistance in thefield. We are deeply indebted to dr J. M. Węsławski and other specialists of the Arctic Ecology group of the Institute of Oceanology, Sopot, for organizing the international expedition aboard the research vessel Oceania of the Polish Academy of Sciences. Our expedition could not have been realized without valuable financial support of the NEWPORT UNIVERSITY, s.r.o., Ostrava and OSTRAVAR Ostrava. Material help was provided by A.Q.C. Prague, MIKROTECHNA Tyn n. Vltavou, OREL Ostrava, LANEX Bolatice and 491

8 OSTRAVAR Ostrava. We would like to express our cordial thanks to all of the institutions. The expedition was partly financed from the Norwegian-Polish research project in the frame-of the project Walrus" of the Norsk Polarinstitutt, Oslo. REFERENCES Duriś, Z., 1992: On a small collection of Crustacea Decapoda from the Bellsund Region, Spitsbergen. Wyprawy Geograficzne na Spitsbergen, UMCS, Lublin: Duris, Z., 1992: A report on the Czechoslovak Arctic Biological and Diving Expedition Spitsbergen'91". Wyprawy Geograficzne na Spitsbergen, 1992, UMCS, Lublin: Duriś, Z., 1993: On a collection of crustacea decapoda from the southeastern Svalbard. Wyprawy Geograficzne na Spitsbergen, UMCS, Lublin (this volume). Węsiawski, J. M., Wiktor, J., Duriś Z., and M. Zajączkowski, 1992: Summer marine biolog survey at Bolscheoya, Eastern Svalbard Arctic Ecology Group Report, 1/92:22 pp. (Inst, of Oceanology, Polish Acad. Sci., Sopot). Address of the author: dr Zdenek Curiś, Institute of Industrial Landscape Ecology, Czech Academy of Sciences, Hladnovska 9, Ostrava 2, Czech Republic 492

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