Showing papers on "Pelagic zone published in 1975"

Vertical distribution of pelagic cephalopods

Abstract: Vertical Distribution of Pelagic Cephalopods. Smithsonian Gontributions to Zoology, number 209, 51 pages, 31 figures, I 975.-The vertical distributions of pelagic cephalopods are analyzed, based primarily on sturlies undertaken in the waters off California, Bermuda, and Hawaii. Much of the information is derived from midwater trawl nets equipped with closing apparatus. Each family that contains pelagic or quasipelagic species is discussed; selected records from the Iiterature are inciuded where necessary. A wide variety of patterns of vertical distribution exists among pelagic cephalo. pods; patterns may be associated with stage of maturity, die! rhythms, or seasonal behavior. The study revealed that several basic types of vertical distributional patterns occur: near-surface dwellers, first order die! vertical migrators, second order die! vertical migrators, die! vertical shifters, die! vertical spreaders, nonmigrators, vertical wanderers, species associated with the .ocean bottom, species exhibiting ontogenetic descent.

The Biology of Pelagic Shrimps in the Ocean

Abstract: Publisher Summary This chapter discusses the biology and ecology of pelagic shrimps. In oceanic waters pelagic shrimps are mostly distributed in water below 160 meters depth by day. In pelagic shrimps the integument is not rigid due to poor calcareous content particularly in the bathypelagic species. Pelagic shrimps are almost absent in the polar regions. The faunal diversity increases from the sub-polar regions to the tropical regions, and rich occurrences of species are seen in the temperate sub-tropical, and tropical regions. The body lengths of pelagic shrimps range from 10–100 mm, however a few species grow up to 130–180 mm. The epipelagic and upper mesopelagic species are transparent or semitransparent with orange or red chromatophores, however all species living in the uppermost 600–700 m depth by day have a more or less uniform pigmentation that varies from deep-red to scarlet. The shrimp biomass is large in inshore waters and localities over the continental slope. It decreases with increasing distance from the coast. Besides the food supply, the vertical distribution of shrimps is principally modified by light penetration and temperature. The chapter also describes the spawning behavior of shrimps. The spawning of epi- arid mesopelagic sergestids is usually heaviest during summer in temperate regions.

Distribution of coccolithophores in marginal seas along the western Pacific Ocean and in the Red Sea

Abstract: The distribution of coccolithophores was studied in the neritic environment along the western margin of the Pacific Ocean: the Inland Sea of Seto, Yellow Sea, East China Sea, South China Sea, Java Sea, Timor Sea, Arafura Sea and Gulf of Carpentaria. The coccolithophore community in the Red Sea was also studied for comparison with the Pacific marginal seas. With minor exceptions, the coccolithophore communities were very similar throughout the neritic areas investigated, but differed completely from the pelagic community in three aspects. Firstly, almost all neritic coccolithophores, regardless of species, suffered various degrees and forms of malformation with relation to the morphology of their coccoliths, while such malformation was rare in the pelagic population. Nitrogen deficiency may cause such malformation. Secondly, the diversity of species in these marginal seas was much lower than in the pelagic environment, although no species was found to be exclusively neritic. Emiliania huxleyi, usually ubiquitous in oceanic areas and in various neritic environments of higher latitudes, was scarce, while Gephyrocapsa oceanica dominated the flora throughout the studied areas. Finally, the horizontal and vertical distributions of the neritic populations were sporadic compared to those of the rather uniform pelagic environments.

Weyl's theory of glaciation supported by isotopic study of Norwegian core K 11

Abstract: Oxygen-18 analyses of pelagic and benthic foraminifera from core K 11 indicate that during the last glaciation Norwegian Sea bottom waters were warmer than in modern times and had the same physical parameters (temperature, oxygen isotope ratio, and salinity) as the North Atlantic deep water. This result indicates that the glacial Norwegian Sea was not a sink for dense surface water, as it is now, and that during glacial times North Atlantic deep water invaded the deep Norwegian basin.

Analysis of the vertical and geographic distribution of the abundant species of planktonic ostracods in the North-east Atlantic

Abstract: Recent improvements in gear and techniques have permitted much more detailed studies to be made of vertical distribution patterns of pelagic oceanic organisms (Vinogradov, 1970; Foxton, 1972). One such development is the RMT 1 + 8 opening-closing net system for sampling plankton and micronekton (Baker, Clarke & Harris, 1973) which can be acoustically monitored in situ for fishing depth, water temperature, flow and net operations. This sampler has been used to study the midwater communities in the N.E. Atlantic over the last 6 years during cruises by RRS ‘Discovery’. It has been successfully operated to depths of 4000 m.

Observations on diel behaviour patterns of North Sea gadoids in the pelagic phase

Abstract: The general biology of the gadoid fishes of the North Sea after recruitment to the demersal fisheries has received considerable attention, but little is known about their behaviour patterns during the period between metamorphosis and assumption of the demersal habit. In the summer of 1969 the Marine Laboratory, Aberdeen, began a series of annual midwater trawling surveys of the northern North Sea (Hislop, 1970, 1972 a , b ; Hislop & Bailey, 1971, 1975). During the surveys observations were also made on various aspects of the biology of the species caught. This paper describes the results of a series of trawling experiments carried out on a cruise of F.R.S. ‘Scarba’ (ex ‘Scotia’) between 12 and 29 August 1971.

Pelagic Tar in the Mediterranean Sea, 1974–75

Abstract: During the period 6 December 1974 to 20 January 1975, the R/V Westward circumnavigated the Mediterranean Sea and took quantitative samples of pelagic tar at 48 stations. These have been compared with a similar survey made in 1969 by the R/V Atlantis II and with some data published in the USSR. In the ‘Ionian Sea’ (between Crete and the Strait of Sicily) the geometric mean of tar concentration has decreased significantly—from 60 mg/m2 in 1969 to 5 mg/m2 in 1974–75. In other regions of the Mediterranean, no significant changes were found. However, in both the ‘Tyrrhenian Sea’ west of Italy and the ‘Alboran Sea’ along the Algerian-Moroccan coast, tar concentrations have increased by about a factor of two, roughly corresponding to the relative increase in tanker traffic in the Mediterranean as a whole. In the ‘Balearic Sea’, 1975 levels were lower than those of 1969, but the data may not be comparable because of the different geographic regions covered.At present, the total standing stock of pelagic tar in the Mediterranean is lower than in 1969, due to the decrease in pollution of the eastern basin. With the reopening of the Suez Canal, changes in the amounts of tar should be carefully monitored as a measure of pollution control effectiveness.

Slender tuna (Allothunnus fallai Serventy): first record of bulk catches, Tasmania, 1974

Abstract: Purse seine catches of 230 tonnes of slender tuna in Tasmania were made in June 1974. The species has heretofore been regarded as rare in Australian waters, and relatively uncommon elsewhere. Surface water temperatures during commercial fishing ranged from 12.0 to 14.0oC. Age estimations by otoliths suggested 4+ to 6+ years for lengths 69.0-91.0 cm. The length-weight relationship was W = 0.000004SL3.322. The tuna were feeding mainly on pelagic Crustacea. Gonad inspection showed that spawning had occurred recently. Three internal parasites (Anisakis sp., Copepoda, Cestoda) were found in 89.3, 95.7 and 61.7% of the 46 fish examined. Fish flesh was extremely oily (10-50%), and mercury analysis gave readings from 0.1 to 0.2 mg/kg.

Summer Distribution of the Nearshore Fish Community near a Thermal Generating Station as Determined by Acoustic Census

Abstract: The relation between thermal plumes and fish abundance and distribution was studied at the Pickering Nuclear Generating Station, Lake Ontario, using simultaneous digital echo counting and temperature monitoring systems during summer thermal stratification of the lake.Fish relative abundance varied from 20.8/10,000 m3 to 1,037/10,000 m3 and both these extreme density estimates occurred in the 7.5–12.5-m depth shell. Also, changes in distribution of the nearshore community were apparent during the study period, July–October. The fish community in July was pelagic and selected 10–11 C and 14–16 C. That same community later appeared to become segregated into benthic and pelagic communities. Thermal plumes, either well defined or diffuse, appeared to have little effect on the pelagic community either because fish were not available to elevated temperatures by habitat selection or because fish failed to respond to increased surface temperatures.

Studies on the zooplankton and hydrology of South-Eastern coastal waters of Tasmania.

Abstract: The zooplankton and hydrology of the south-eastern coastal waters of Tasmania - Coastal waters off the East Coast, Inshore coastal waters and the Derwent River Estuary are investigated. THE ZOOPLANKTON : SYSTEMATICS Zooplankton species found during the studies are recorded, illustrated, and discussed taxonomically where appropriate. A brief account is given of the distribution of the 71 Pelagic Copepods, 8 Euphausids, 1 Sergestid, 11 Chaetognaths and 7 Pelagic Tunicates. Except for 2 Copepod species which are assigned to a genus, the remainder are positively identified. Amongst the species recorded, 22 Copepods are new to Australian waters whereas 38 Copepods, 1 Euphausid and 2 Chaetognaths are new records for Tasmania. Keys to the genera and species are also given. THE DISTRIBUTION OF ZOOPLANKTON OFF THE EAST COAST AND THEIR VALUE AS BIOLOGICAL INDICATORS Ten Cruises when twelve Stations were usually operated during each Cruise, totalling 89 Stations from August 1971 to May 1973 were made for surface samples off the East Coast. Thirty-five species, mainly based on their preferences for depth or temperature/salinity are selected and analysed from grouping of species and Stations by the computer program DIVINFRE . Six types of water masses involving three water masses characterized by five species-groups such as, (i) Coastal; (ii) mixed Coastal and Sub-tropical; (iii) mixed Coastal and Sub-antarctic; (iv) mixed Sub-tropical and Sub-antarctic; (v) Sub-tropica 1; and, (vi) Sub-antarc tic, are found off eastern Tasmania. iv Some literature contradictions relating to the position of the Sub-tropical Convergence and salinity of Sub-antarctic waters are discussed and it was found that the convergences oscillate along the East Coast with seasons. ZOOPLANKTON AND HYDROLOGY OF INSHORE COASTAL WATERS. Three Stations in inshore waters were operated at monthly intervals for a period of 12 months from August 1971 to July 1972, collecting samples from surface, 10m and 20m depths during day and night. Seasonal diurnal vertical distribution of most of the species and biomass for the 3 Stations are given and discussed. Seasonal zooplankton composition for the Station at the mouth of the Derwent Estuary is given. Relative composition of indicator zooplankton species groups (inshore coastal, coastal and oceanic) are used to determine the influence of estuarine and intrusion of oceanic waters to the region. The possible oceanic waters involved and effects of movement of waters on the accumulation of heavy metals in oysters found in the Derwent Estuary and adjacent waters are mentioned. Such influences are possibly the main factors affecting the seasonal cycles of the zooplankton composition and biomass. ZOOPLANKTON AND HYDROLOGY OF THE DERWENT ESTUARY Collections from two Cruises, on 1st October 1973 and 23rd April 1974 when 10 Stations extending 50 kilometres upstream were operated during each Cruise, are studied. Hydrologically, the region covers from freshwater to marine, 17 zooplankton species representing freshwater, estuarine and marine environment being found. The results are compared with those of previous and similar hydrological and ecological studies.

White bait resources of the south west coast of India

Abstract: The most important landing is that there exists in the sea between Ratnagiri and Tuticorin a sufficiently large resource of Anhoviella spp. (Whitebait), which 1s at present exploited to a small extent only. The estimates of the Pelagic Fishery Project reveal that the total resource of whitebait at the time of its highest availability is about 1/2 million tonnes (0 . 5 2 million) which is over 50%; of the total annual marine fish landing in India.

Studies on new or little known polychaetes from the Indian seas 4. On a new record of Sigambra tentaculata (Treadwell) (Pilargidae), from the southwest coast of India along with observations on its early larval stages

Abstract: Sigambra tentaculata (Treadwell) which is known previously from East Atlantic and Western Pacific Ocean is reported from Vizhinjam, southwest coast of India for the first time. The pelagic and benthic larval stages of the species are described and illustrated.

Relation Between Egg Size, Growth, and Natural Mortality of Larval Fish

Abstract: A set ofdensity-dependent growth and survivorship equations is derived from evidence that the instantaneous death rate in the sea is inversely proportional to particle size. The survivorship equation reproduces several well-known phenomena observed in fish populations. It predicts: 1) that winter and spring spawning species ought to produce larger eggs than summer spawners, 2) that it is advantageous for species that spawn in batches to produce progressively smaller eggs in spring and summer, and 3) that the death rate ofa cohort offish should decrease continuously as the survivors grow and approach the critical size. The biological basis for the observed variation in the size ofpelagic fish eggs and larvae is thought to be due primarily to trophic relations within the pelagic community. It is suggested from what is known ofthe relative abundance and foraging capabilities ofdifferent sized particles, that the survival rates oflarval andjuvenile fish should increase as they grow and occupy a progressively higher position in the food chain.

Kopalny zespół quasi-sargassowy z warstw menilitowych jednostki skolskiej Karpat polskich.

Abstract: FOSSILS OF THE QUASI-SARGASSO ASSEMBLAGE IN THE MENILITE BEDS OF THE SKOLE UNIT, POLISH CARPATHIAN MOUNTAINS Summary An attempt to interpret the co-occurrence of deep water fish ( Myctophidae, Gonostomatidae, Sternoptychidae, Gemphylidae ), pelagic fish ( Clupeidae, Carangidae ), and shallow water fish ( Syngnathidae ) as well as of pelagic algae ( Phaeophyta ) is presented. The authors compare the assemblage derived from the Oligocene of the Polish Carpathian Mountains with that expected to accumulate nowadays at the bottom of the Sargasso Sea. On the grounds of serious analogies between the anticipated tanatocoenoses of this sea and the examined fossil assemblage the latter has been named the Quasi-Sargasso assemblage. According to the present authors the formation of the Quasi-Sargasso assemblage can be related to various stages of the algae evolution. Either large fragments of algal meadows were detached from the shore and drifted towards the open deep sea (together with the co-existing shallow water fish fauna) or the algae formed populations capable of self-dependent existence in the open sea. In the latter case they would constitute a habitat for autochthonous and already pelagic fish fauna. The first concept calls for repeated detachment and drift of algae during a long period towards the same area. The second possibility is supported by the occurrence of algal fragments without skeletons or even scales of Syngnathus in the older bathypelagic sediments of the Menilite beds (from the Jaslo shales horizon upwards). Normal 0 21 false false false PL X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:Standardowy; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; text-indent:35.45pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin;}

A towed dual-frequency hydroacoustic fish assessment system

Abstract: A towed hydroacoustic system that provides rapid and precise estimates of pelagic (mid-water) fish stock abundance has been developed at the University of Washington. The system is self-contained, and therefore suitable for use on "ships of opportunity." It has been used to assess pelagic fish as part of the Coastal Upwelling Ecosystems Analysis program sponsored by the National Science Foundation.

Preliminary results from a bottom trawl survey of Lake Rudolf with additional notes on trials with a midwater frame trawl

Abstract: This paper includes a short report on preliminary midwater hauls with a frame trawl. The object is (a) to study the relationship between the vertical distribution of pelagic fish and the scattering layer, and (b) to find out if certain species, which at times occur abundantly in the bottom-trawl on the shallow-water frontiers of the scattering layer, might extend into offshore waters to constitute an important pelagic resource.

Preservation of Inshore Male Capelin (Mallotus villosus) Stored in Refrigerated Sea Water

Abstract: Male spawning capelin(Mallotlrs rillosas) from an inshore stock were preserved ungutted in refrigerated sea water, both with and without carbon dioxide Contrary to results found with other small pelagic species, refrigerated sea water in both forms leads to a rate of degradation considerably faster than that for similar capelin held in ice Major taste and texture changes were obvious as early as the second day, followed by rejection of the fish at day 3 Analysis indicated that in the samples stored without carbon dioxide, bacterial decay was fast, as was the hydrolysis of lipid to free fatty acid Spoilage due to textural changes was faster when carbon dioxide was added to the sea water lt was concluded that carriage or storage of spawning inshore male capelin in either form ofrefrigerated sea water is not to be recommended over boxing in ice