Bottom Animals Research Articles

Temporal changes in concentration of radiocaesium in lake sediment and fish of southern Finland as related to environmental factors

In 1992 the concentration of radiocaseium in the surface layer of bottom sediment of 52 lakes of southern Finland was found to have declined on average to 27,4% of 1987–1988 levels and to 25.7, 28.0 and 38.6% of 1988 levels in the tissues of perch, pike and roach, respectively. The sediment radiocaesium concentration was higher in larger lakes and in lakes having a large catchment, but lower in oligotrophic than eutrophic lakes, when the total amount of electrolytes and organic matter was high. The concentration of radiocaesium in perch and pike was lower in eutrophic than oligotrophic lakes and lower in all three fish species when the concentration of electrolytes was high. Lower radiocaesium values in both sediments and fish of eutrophic when compared with oligotrophic lakes may be due to a greater dilution of this contaminant into a higher biomass. Water colour and pH were negatively correlated with radiocaesium in perch only. A lower radiocaesium level in perch in humic water lakes may be due to an adsorption of radiocaesium onto humus particles which reduces its bioavailability and transfer along the food chain. Radiocaesium in fish and in sediment were positively correlated with each other for perch and roach whose diets comprise mainly the detritivore or sediment feeding bottom animals. In perch the radiocaesium concentration was high when the water retention time of the lake was long. A tropic level bioconcentration was evident in the threefold higher radiocaesium level in predatory pike compared with roach. The decline in radiocaesium was most pronounced in sediment when the catchment area was large, when the water pH was high and when the sediment surface contained a low proportion of organic matter. In fish the largest decline in radiocaesium was recorded in pike from eutrophic or shallow lakes and when the lake water retention time was short. In perch and roach the reduced radiocaesium levels were not due to effects of water quality or lake morphometrical properties. Two different sediment core samplers, a Kajak corer and a Limnos corer, gave comparable results.

Valve movement of the freshwater mussel Anodonta anatina: a reciprocal transplant experiment between lake and river

The effects of source and caging on the valve movements of the freshwater unionid mussel (Anodonta anatina) were studied in a reciprocal transplant experiment between a lake and its outflow. Caged mussels were moved and compared with those remaining in their natural environment on the lake or river bottom. At both sites, the mussels from the study site and the transplanted mussels from the opposite site were monitored simultaneously. In river the averaged weighted valve openness was higher and the number of valve movements was lower than in the lake. The mussels monitored in the lake exhibited a diurnal rhythm of valve movements which differed between the lake-bottom and the caged animals. Caging was found to increase valve openness. On the other hand, little variation appeared in valve openness between caged and bottom animals in the river, where diurnal rhythms were almost nonexistent. In the river the valve movements were more variable in respect to time than in the lake.

Northern Gulf of Mexico Hydrocarbon Seep Communities: Implications to the Petroleum Industry: ABSTRACT

Most animals consume organic food sources based on primary productivity at the base of the food web. Little food reaches deep-sea bottom animals which are usually small, fragile, and sparsely distributed. Recent discoveries of chemosynthetic organisms worldwide have led to investigations into the taxonomy. ecology, biochemistry, and physiology of these forms. The dominant animals in these communities, several large species of vestimentiferan tube worms and bivalve mollusks, energetically use dissolved gases (primarily methane and hydrogen sulfide) issuing from the sea bottom under certain geological conditions. Endosymbiotic bacteria aid metabolic pathways. The large chemosynthetic animals and their dense populations (orders of magnitude over background) are the exceptions that prove the rule that food is an important limiting factor in the deep sea. The discovery of relatively shallow, luxuriant gas-seep communities on the Louisiana upper slope raises concerns on the environmental effects of nearby petroleum operations. To protect these communities, the Minerals Management Service requires photographic bottom surveys in depths from 400 to 900 m if geophysical evidence of seeps (wipeout zones or streams of bubbles) is found. If found near proposed well locations, high-density communities must be avoided thereby preventing physical damage from any structure. Deep-sea community surveys can be expensivemore » and can result in alternative siting plans and development delays. But Minerals Management Service's requirements should conserve these shallow communities that have considerable value as natural laboratories accessible to academic study. We know little about the permanence, dynamics, recruitment recovery potential. and life requirements of chemosynthetic communities. Additional studies, funded by the Minerals Management Service, have been proposed.« less

Long-term changes in macrozoobenthic abundance on the tidal flats of the western part of the Dutch Wadden Sea

For 20 years (1969–1988), larger bottom animals have been sampled quantitatively once or twice annually at 15 stations scattered over Balgzand (a 50 km2 tidal flat area in the westernmost part of the Dutch Wadden Sea). In 29 species, numbers were sufficiently high to allow a statistical evaluation of the fluctuation patterns of their annual densities. The results revealed two main trends: (1) a sensitivity to low winter temperatures in 12 species, causing low densities in these species immediately after a severe winter (1979, 1985, 1986 and 1987) and relatively high densities during a period with some mild winters in succession (1973–1975); (2) an upward long-term trend in 11 (other) species, causing upward trends (viz. roughly a doubling) of total macrozoobenthic biomass and production over the 20-year period of observation, probably as a consequence of increasing eutrophication. By far the major part of the species thus exhibited either of these two patterns, causing total biomass and species number to be governed largely by the above two trends. Results of less frequent sampling (once per 5 or 10 years) of 26 transects scattered over the ≈500 km2 of tidal flats of the whole western half of the Dutch Wadden Sea showed that the two trends also represent the changes occurring in a much larger area. Some local departures from the general patterns are discussed and related to specific causes.

Energy Flows in Populations and Communities of Aquatic Animals

AbstractThe energy assimilated by single individuals of aquatic animals throughout their life times and by populations and communities of aquatic animals during the growth season has been studied with due regard for the definitive weight of the single individual and the mean biomass of populations and communities. Energy assimilated throughout life by invertebrates of different systematic positions, definitive size and life duration is about 2.5 times as high as the energetic content of their definitive mass. The energy flow in populations of benthic animals is about 5 times as high as the seasonal average biomass, and in populations of planktonic animals it is 40 times as high. The energy flow in bottom communities is almost 10 times and in planktonic ones 35 times as high as the average seasonal biomass of communities. Specific production (P/B coefficient per 24 h) for communities of bottom animals was 0.013 per 24 h. The average value of the K2 coefficient (net growth efficiency) calculated for an individual's life time is about 0.4 in populations of bottom animals, the K2 for vegetation seasons is 0.26, and for communities it is 0.2 (per vegetation season). Increasing complexity of the biological systems is accompanied by an increase in the specific energy flow and a decline in the efficiency of food energy utilization for production.

The partitioning of secondary production among species in benthic communities

The way in which total secondary production is partitioned amongst species in various macrofauna communities ( Amphiura, Venus, Abra, Modiolus) around the British Isles is discussed. When the proportion of total production is plotted for each species, ranked in order of productive importance, curves are produced which are characteristic of particular physical conditions. The shapes of the curves are independent of the actual species involved, but depend on the proportion of individuals in the community which adopt a particular feeding behaviour, and the scope for diversification within trophic groups. The form of these curves correlates closely with bottom currents and associated bed-stresses, since these affect both the nature of the food supply to bottom animals and the nature of the substrate. These observations have important implications for the structure and functioning of benthic communities. Comparison of production partitioning in the meiofauna of mud and sand substrates indicates a remarkable similarity within trophic groups although the partitioning of production between trophic groups is very different. The shapes of production-rank curves again appear to depend on the scope for diversification within trophic groups. In the meiofauna resources are partitioned more equitably than in the macrofauna. There is a marked discontinuity in the lognormal distribution of body sizes within integrated benthic communities at the meiofauna-macrofauna size boundary.

Die umweltfaktoren, die die verbreitung und entwicklung von Chalcalburnus tarichi (PALL. 1881) (Pisces: Cyprinidae) in Burdur-See begrenzen

Burdur Lake, an entirely closed and brackish water lake, having an area of 190 km 2 and 76 m depth, is located in the “Lakes Region” of Anatolia, 4 km from the west of Burdur city. There have been made many attempts to breed an economically important fish population but all attempts were unsuccessful. During 1946–1948 some hydrobiological investigations were carried out. According to these investigations, hydrobiological conditions of the lake were found to be suitable for Chalcalburnus tarichi (PALL. 1881) (Pisces: Cyprinidae), a fish which is endemic to the Lake Van in eastern Anatolia. Since 1966 an attempt has been made to breed Chalcalburnus tarichi artificially. This attempt was successful, but the economic productivity was not in the estimated level. These fish live in all the depth of the lake, but during the breeding season, they go into fresh water streams flowing into the lake. To find out the reasons of the productivity losses, new hydrobiological investigations have been going on since 1969. Two research stations have been chosen (Fig. 1), where water, plankton and bottom samplings have been collected for hydrobiological research. Nansen bottles were used to take the water samples, in 10 m intervals, from the surface of water towards the bottom. The chemical analysis of water have been done according to the standard methods given in Welcher (1963). The Winkler method is used to find out the amount of dissolved oxygen (Welcher, 1963). Plankton was collected in 10 m intervals by usual type Closing net (20 cm dia, mesh size of 0.05 mm). The amount of plankton per m 3 has been calculated according to the Settling methods of Welch (1948). Bottom samples were collected by Ekman's Dredge at four different regions marked (a), (b), (c), (d), on Fig. 1. Samples were wet sieved through four graded sieves (mesh sizes 0.5–2.0 mm). The number of the collected bottom animals per m 2 were calculated. Observations showed that, the direct flow of waste waters having organic materials from the Burdur Sugar Mill, Milk-Cheese factories and Attar of Rose industries and Hemp ( Cannabis sativa) maceration remnants go to the bottom of the lake, therefore, unoxygenated and thereby a hydrogensulphonized water layer is formed by the above mentioned waste products. The unoxygenated water layer level increases 2–2.5 m per year towards the surface. This pollution has caused this unexpected loss of productivity of fish, for this water layer harms the bottom feeding and planktonic organisms and restricts the spreading and development of the adopted Chalcalburnus tarichi (PALL. 1881). It is also clear that this situation is a threat to the future of the lake and its environment.

X-Ray Analysis of Sediment Regions and Transport of Sediment Particular Material on the Gill of the Fingernail Clam, Musculium Transversum

Fingernail clams are dominant bottom dwelling animals in some waters of the midwestern part of the U.S. These clams prefer big river habitats with a silt bottom where peak numbers may exceed 100,000/m2 as in Keokuk Pool, Mississippi R. In the mid 1950’s, fingernail clams disappeared from a 100-mile section of the Illinois R., a tributary of the Mississippi R., due to unknown causes. In order to determine if the unknown factor(s) in the Illinois R. are present in the bed of this river, a sediment core of material was obtained. This material was divided into four samples (A thru D, upper to lower region, respectively). Particle matter from each sample was characterized as to size(μm), mass(mg/1), and concentration(particles/1). The lateral cilia on the gill (Fig. 1) of the fingernail clam are primarily responsible for the transport of sediment particles over the lamellae. These cilia are under the control of the nervous system and as such can respond directly to adverse environmental stress factors. Therefore, gill preps were isolated and subsequent measurement of the effects of temperature on rate(mm/sec) of sediment transport of samples A thru D were determined from dorsal to ventral border of the gill. For x-ray analysis, mud samples were dried and mounted on C stubs, coated with C, and examined in a Cambridge IIA SEM fitted with an Ortec computer-based EDS system.

Micro‐stratigraphy of sediment laminations deposited in a chemically stratifying eutrophic lake during the years 1913–1976

A sequence of laminated sediment, 30 cm long, deposited in the deepest part of an eutrophic lake, Lovojärvi, in southern Finland, was analyzed microscopically. Seasonal changes in sedimentation were found to be well retained, due to the absence of bottom animals and the rather high sedimentation rate. Delimitation of the annual layers was based primarily on the repeated cyclic pattern observed in the stratigraphy of the planktonic diatoms. The annual character of these diatom cycles was established through their agreement with information obtained during three earlier one‐year studies on the plaktonic diatom community. In the lower part of the sequence studied the laminated structure appeared quite regular, the annual layers being composed of pairs of a whitish, diatom‐rich “summer” layer, and a dark brown, more organic “cold season” layer, but in the upper part the laminations were more variable, due to allochthonous inputs caused by human activity in the drainage area. Several thick clay layers which could be dated back to known constructional events on the lake shore aided the interpretation of this sequence, within which prominent alterations in the planktonic diatom flora were also observed. The gradual increase in the proportions of acidophilous diatoms during the past decades was interpreted as indicating a slight lowering in the trophic status of the lake, primarily due to the termination of flax soaking, which had been going on by the lake shore for centuries.

Mercury and chlorinated hydrocarbons in zoobenthos of Lake Päijänne, Finland.

The average amounts of mercury, PCBs, and sigma DDT (primarily DDE), found in macrozoobenthos, on the wet basis, in Lake Päijänne, Finland, for the time period 1972-1974, were 79 ng/g, 29 ng/g, and 8 ng/g, respectively. Lindane was found in negligible amounts in only 2% of the samples examined; aldrin was present in 10% of the samples; no dieldrin was detected. Mercury and PCB concentrations varied regionally in the lake. PCB and sigma DDT concentrations were greater in the predatory bottom animals than in the herbivores or detritus feeders, and the amounts of chlorinated hydrocarbons were greater in profundal animals than in littoral animals. No significant correlation was apparent between the amount of residues found and the weight of the animal (e.g. Anodonta). A significant positive correlation was evident in the amounts of PCBs and sigma DDT in most of the taxonomical groups. Spongilla lacustris and Anodonta piscinalis were excellent species for monitoring purposes.

Dynamics of Detritus in a Small Stream in Southern Sweden and Its Influence on the Distribution of the Bottom Animal Communities

Transport and availability of various size fractions of organic material along with bottom structure and benthic invertebrates, grouped with respect to feeding types, were examined along an 8 km long stream in southern Sweden. Transport of coarse particulate organic material (CPOM) was insignificant, while considerable amounts of fine particulate (FPOM) and dissolved organic matter (DOM) were carried downstream. DOM showed little variation and was constantly 2-3 times the energy of suspended FPOM. Export of DOM was 5 times as high as that of FPOM, total organic output being twice as high as leaf input. On a stony bottom shredders and scrapers dominated, whereas scrapers, deposit feeders and filter feeders were abundant where sedimentation was heavy. Downstream the section with most extensive sedimentation all categories including predators were well represented.

Composition and dynamics of the bottom animals in the littoral zone of Dojran Lake, Macedonia

Composition and dynamics of the bottom animals in the littoral zone of Dojran Lake, Macedonia

On the Horizontal Distribution of the Profundal Bottom Fauna in a Limited Area of Central Lake Malaren, Sweden

The spatial distribution of bottom animals in a large, flat, and unexposed bottom area (about 8 km2) in central Lake Malaren was investigated. As far as could be seen from preliminary tests the area was homogeneous in most respects. Working from the ice in all 42 tube samples and 6 Ekman samples were obtained from randomly distributed quadrats in a grid measuring 100 × 50 m2. A 0.3 mm gauge net was used for sieving. The mud surface area covered with the tube samples was about 40 cm2. Different methods of illustration were applied to demonstrate how many samples were actually required to show certain characteristics in the bottom fauna. For most purposes the accumulated mean value (cf. Kajak, 1963) was close enough to the stable mean value already after two or three tube samples for both chironomids and tubificids. In order to get a good idea of the five major constituents amongst tubificids (about 96% of all tubificids) two tube samples were found to be quite enough in this particular test. For the seven major constituents (about 99% of all tubificids) four tube samples were sufficient — or one single Ekman sample. The main constituents were well represented after two tube samples or one Ekman sample. Very little further information about the major constituents was obtained after the minimum number of samples mentioned above had been taken. A statistical study based on the same material was performed by a group of statisticians at the Institute of Statistics, University of Stockholm. Different statistical tests were applied to the material. Due to the relatively small number of observations nothing definitely could be said about the actual distribution of tubificids or chironomids in the area. The chironomids seemed to conform better to the Poisson distribution than to the Negative Binomial distribution, while the tubificids showed greater agreement with the Negative Binomial distribution.

Vertikalverbreitung und zelluläre Hitzeresistenz von Bodentieren aus der Possjet-Bucht (Japanisches Meer)

1. Investigations on 15 mass species of bottom animals (Bivalvia, Gastropoda, Asteroidea, Ascidia), performed by means of aqualungs in semi-enclosed bays of the Possyet Bay (Peter the Great Bay of the Japan Sea), have revealed a clear zonality in their vertical distribution. This finding is in contrast to the situation found near islands and capes of Peter the Great Bay, where species distributions are weakly connected with depth, but to a considerable degree determined by the nature of substrate, degree of tides and presence of predators. 2. These differences may be explained by differences in summer temperature conditions, considerable decrease of the temperature gradient with increase of depth in semi-enclosed bays, insignificant surface temperature differences and, in depths of about 20–30 m, by intensive water mixing near islands and capes. 3. Comparison of the vertical distribution of species from the Possyet Bay with their cellular heat resistance (species-specific feature, used for characterizing genetic heat adaptation) reveals conformity between these indices. 4. These results and literature data suggest that the differences in vertical distribution of the bottom invertebrates living in coastal waters are the result of the species-specific adaptation of their cells to environmental temperature; differences in protein structure of different animals are considered to provide the basis of this phenomenon.

A Preliminary Survey of the Benthic Macrofauna and Sediments in Lochs Etive and Creran, Sea-Lochs Along the West Coast of Scotland

The hydrographic conditions in the two sea-lochs is briefly described where relevant to the survey of the benthos. Seasonal changes in temperature and salinity in Loch Etive appear to follow roughly the local coastal pattern but usually with a lag in timing that is considered to be because of the restricting effect of the twin sills. Replenishment of deep-basin water by ventilation over the sills is spasmodic and controlled by surface stratification; the latter being due primarily to freshwater runoff. This situation contrasts with Loch Creran which has only a small catchment and where the seasonal hydrography closely follows the pattern outside. Other possible reasons for the differences observed between the two lochs are discussed.The bottom fauna of both lochs was sampled semi-quantitatively with an anchor dredge at 22 stations in Loch Etive and 8 in Loch Creran at depths from 7–117 m. A detailed list of the fully marine fauna present is given. The species occurrences in the single-haul samples are compared objectively using a coefficient of similarity of the presence/absence records. An attempt is made to relate the groupings shown up to the classical ‘bottom community’ concept, to the feeding-type categories of the bottom animals and to analysis of particle size of sediment samples taken at the same stations. A correlation to sediment type was apparent. This is considered to owe as much to local hydrographic conditions which the sediment reflect as to the sediment itself.

A Theory Concerning the Distance Travelled by Animals Entering the Drift of a Stream

Stream bottom animals were introduced into a stream by disturbing the gravel at increasing distances upstream from a drift sampler. The relationship between the number of animals arriving at the sampler and distance of origin of the animals was found to be Nx = N0 e−RX where N0 is the number of animals introduced, R is the rate of return to the gravel of the animals, and X is the distance upstream from the sampler. The maximum distance travelled was 45.7 m and the mean distance 10.7 m. The values of R for individual species ranged from 0.0517 to 1.962 and values of the mean distance travelled from 19.3 to 0.5 m. Specific differences could be accounted for by differences in structure or behaviour of the animals.From these observations, a model of stream drift is developed. Two previously published experiments are shown to conform to model relationship: (1) recovery of drift density downstream from a blockage in the experiment of Waters (Ecology 46: 327–334, 1965); and (2) distribution of times taken to regain a foothold on the substrate by mayfly nymphs released into a current (Madsen, Flora Fauna 72: 148–154, 1966; Hydrobiologia 31: 337–349, 1968).Since a stationary feeding fish such as a trout can be considered to be a "drift sampler" intercepting particles in the current, some suggestions are made about the development of a theory concerning the delivery of items of food to such a predator.

Biological Effects of Spoil Disposal in Chesapeake Bay

Field studies were made on the biota of the upper Chesapeake Bay under a design related to the shallow water disposal of channel sediments. No gross effects were observed on the phyto-zooplankton, fish eggs and fish larvae of adult fishes. Some bottom animals were smothered over a wide area. Several benthic species survived deposition, and certain species began repopulation soon after deposition.

Effect of pollution on the benthos off gothenburg

1. Bottom fauna in the mouth of the river Gota alv and its estuary was studied. 2. The river bottom in the city of Gothenburg and the bottoms of the harbour area and the river mouth are strongly polluted. The pollution has dispersed almost 4 to 5 nautic miles outside that area. 3. There are no bottom animals in the river bottom by the town. 4. In the oxidized surface layer of the sediments in the harbour area some species have mass occurrences. 5. In the same places the biomass reaches its maximum. 6. Pollution has a diminishing effect on the number of species at outer localities. 7. Species which favour polluted areas are e. g.Capitella capitata, Polydora ciliata, Nereis diversicolor, Macoma baltica, Mya arenaria, Paramphiascopsis longirostris (Harpacticoida) and Nematoda spp. 8. The history of the developing pollution can be followed by the aid of old faunistic observations and material stored by the Gothenburg Museum of Natural History.

A quantitative and qualitative study of the plankton of Alexandria Waters

Monthly observations on composition and quantity of plankton together with hydrographical conditions showed the following: (1) An abrupt drop in salinity occurs in September, accompanied by a considerable increase in silicate as a result of mixing with Nile waters. Phosphate shows a winter maximum and becomes exhausted after the Nile bloom. (2) A massive increase in phytoplankton production of exceptional amplitude in the Mediterranean follows the Nile flood in September–October. It is due to Chaetoceros socialis, Skeletonema costatum, Hemiaulus sinensis. A smaller early spring rise also occurs. (3) Small copepods, tintinnids and larvae of bottom animals are the main zooplankton organisms. Their periodic increases are responsible for the great rises of spring and early summer associated with a fall in phytoplankton.

The food supply as a factor regulating the population dynamics of bottom animals

The food supply as a factor regulating the population dynamics of bottom animals