Marine Benthos Research Articles

Marine benthos near the Saldanha Bay iron-ore loading terminal

The development of Saldanha Bay (33 degree S/18 degree E) for the export of iron-ore required the construction of a long breakwater, loading terminal and jetty. Associated dredging operations removed 25 million cubic meters of sediment and resulted in significant changes in the faunal structure of the bay (Moldan 1978). The present study investigated the marine benthos near the completed and functioning iron-ore loading terminal and the data may be useful in the long term monitoring of the effects of port development and industrialization of Saldanaha Bay. It appears that the benthos beneath the iron-ore loading jetty at Saldanha Bay differs from that of other areas in the bay. Macrofauna is dominated by Prionospio sexoculata which is tolerant of adverse conditions whilst meiofauna and bacteria numbers are higher under the jetty than elsewhere in Saldanha Bay.

A Physico-Chemical Method for the Extraction of Marine and Estuarine Benthos from Clays and Resistant Muds

In making benthic surveys it is often difficult to extract all the animals from the various sediments in good condition. Even the IBP Handbook (Holme & Mclntyre, 1971) does not give comprehensive details of methods for extracting animals from the complete range of sediment types. The greatest difficulty is presented by clays and compacted silt. In recent work we have had very satisfactory results by using the following procedure. Core and grab samples taken in the field are stored in seal-tight buckets for processing in the laboratory. In the case of grab samples taken from boats, preliminary sieving is performed on site and only the resistant sediments returned to the laboratory. The samples are broken into pieces of approximately 100 cm3 or less and stored in 5 % formaldehyde solution using a volume about three times that of the sediment. This serves to fix and preserve the fauna and also helps in the breakdown of clays. At this stage samples may be stored for a long time. Wherever layers of soft mud are found among the resistant material they are washed off, sieved and the fauna preserved separately. The resistant samples are then frozen in a domestic freezer and left for 24 h before thawing. The freezing is very effective in breaking down resistant sediments into small particles, thus releasing the animals, which can readily be removed by elutriation. Normally, most animals seem to be adversely affected by freezing in much the same way as some vegetables lose their consistency when frozen (an exception to this are members of the polychaete family Phyllodocidae). However, the prior treatment with formalin seems to protect the tissues from damage by freezing.

Marine benthos from Davis Station, Eastern Antarctica

<P>Marine benthos from 24 nearshore sites in the vicinity of Davis station, eastern Antarctica, was sampled from the sea-ice. The sediments were poorly sorted and mainly of wind-blown origin. Thirty-two animal taxa were recognized and most crustaceans were identified to species level. Three habitat types were characterized by their community composition and physical environment: (1) species-rich areas with abundant macrophytes; (2) deep anoxic muddy basins with deposit-feeding species; and (3) poorly sorted sands with mainly motile fauna. Two amphipod species were recorded as new for eastern Antarctica.</P>

Paleoecologic Interpretation of Environmental Stability--A Different Approach: ABSTRACT

Evolutionary patterns, taxonomic diversity, and genetic variability commonly have been used to interpret environmental stability in ancient communities. Paleoecologists have lamented the imprecision of these interpretations. Much of the imprecision was due to inadequately defined species distribution within units. The problem here is that adult organisms, particularly marine benthos, occur in isolated patches. By contrast, larval and juvenile forms, commonly ignored in paleoecologic studies, are more widely distributed and much greater in number. They also are more sensitive to subtle environmental fluctuations. This greater distribution and larger population size of younger organisms is well exemplified by the fossils recovered from acid residues of limestone units from he 240-ft (72 m) thick Kope Formation (Cincinnatian Series). In each of the five sections studied, at least half of the individual layers contained large populations of larval and juvenile organisms. Adults of the same species of these varied taxa are comparatively rare, however. Taxa represented include gastropods, pelecypods, and brachiopods. Any paleoecologic interpretations based on adult forms only would be drawn from much more restricted information than one drawn from all stages of the life cycle represented in these samples. It is suggested that much more precise interpretations of environmental factors such as stability and diversity can be drawn from analyzing remains of the entire life cycle, rather than just adult forms. End_of_Article - Last_Page 463------------

Some problems of ecological studies on marine benthos

Some problems of ecological studies on marine benthos

The Mesozoic marine revolution: evidence from snails, predators and grazers

Tertiary and Recent marine gastropods include in their ranks a complement of mechanically sturdy forms unknown in earlier epochs. Open coiling, planispiral coiling, and umbilici detract from shell sturdiness, and were commoner among Paleozoic and Early Mesozoic gastropods than among younger forms. Strong external sculpture, narrow elongate apertures, and apertural dentition promote resistance to crushing predation and are primarily associated with post-Jurassic mesogastropods, neogastropods, and neritaceans. The ability to remodel the interior of the shell, developed primarily in gastropods with a non-nacreous shell structure, has contributed greatly to the acquisition of these antipredatory features.The substantial increase of snail-shell sturdiness beginning in the Early Cretaceous has accompanied, and was perhaps in response to, the evolution of powerful, relatively small, shell-destroying predators such as teleosts, stomatopods, and decapod crustaceans. A simultaneous intensification of grazing, also involving skeletal destruction, brought with it other fundamental changes in benthic community structure in the Late Mesozoic, including a trend toward infaunalization and the disappearance or environmental restriction of sessile animals which cannot reattach once they are dislodged. The rise and diversification of angiosperms and the animals dependent on them for food coincides with these and other Mesozoic events in the marine benthos and plankton.The new predators and prey which evolved in conjunction with the Mesozoic reorganization persisted through episodes of extinction and biological crisis. Possibly, continental breakup and the wide extent of climatic belts during the Late Mesozoic contributed to the conditions favorable to the evolution of skeleton-destroying consumers. This tendency may have been exaggerated by an increase in shelled food supply resulting from the occupation of new adaptive zones by infaunal bivalves and by shell-inhabiting hermit crabs.Marine communities have not remained in equilibrium over their entire geological history. Biotic revolutions made certain modes of life obsolete and resulted in other adaptive zones becoming newly occupied.

ベントス研連誌No.13/14正誤表

ベントス研連誌No.13/14正誤表

Detecting two-dimensional spatial structure in biological data.

Cliff and Ord (1973) made versatile methods available for the direct utilization of location data in the analysis of dispersion patterns, but their monograph has as yet seen little use in the ecological literature. Application of their weighted forms of Geary's c and Moran's I indices of spatial autocorrelation to some marine benthos data demonstrates a diversity of population structure not anticipated on the basis of more common measures of pattern. These indices provide objective means to evaluate numerous recent spatial models and hypotheses in geographical ecology and genetics. The procedures are particularly attractive because (1) they efficiently utilize data which are often wasted (i.e., sample coordinates), (2) their application puts few constraints on sampling designs which would otherwise be employed, and (3) they reveal and quantify pattern differences which are not obvious to the untrained eye.

An Improved Reineck Box for Sampling Coarse Sand

AbstractA Reineck Box core sampler has been modified for quantitative use in the marine benthos. The modifications are inexpensive and easily accomplished in any machine shop. Samples have been successfully taken in medium coarse to fine sands for layer by layer analysis. The apparatus has a high degree of efficiency, takes a large volume of sediment, and produces an undisturbed core.

The marine benthos of Arctic and sub-Arctic continental shelves

The study of marine life from the bottom of Arctic and sub-Arctic seas has long been a topic of scientific interest, and such work represents an important part of contemporary biological research in the polar regions. Contributions to this field have been made through the collective efforts of investigators from many nations over the years and include findings of considerable significance for life science studies as a whole, as well as for specific polar problems. Together with contemporary research on the pelagic and planktonic biota of northern waters, current work on the bottom fauna (benthos) offers much potential for developing our fundamental knowledge of biological processes in the Arctic seas.

Population structure, food relations and ecological role of marine oligochaetes, with special reference to meiobenthic species

Data on abundance, biomass and biovolume demonstrate the significant ecological role of oligochaetes in the littoral marine benthos. Their numerical and productive importance is comparable to that of many other common meio-and macrofauna groups from various littoral areas. Oligochaetes often exhibit nutritional specialization (e.g. bacteria or diatoms attached to detritus or sand grains). Consequently, food supply can control their population structure and distribution. Few oligochaetes are, apparently, consumed by predators. Hence, only a small portion of their biomass is transferred to higher trophic levels, while the main part is decomposed directly. Most oligochaetes seem to represent final links of rather short food chains. Ecologically, marine oligochaetes attain major importance only in littoral areas.

Depositional environments in the lower part of the Great Oolite Group of Oxfordshire and North Gloucestershire

In Oxfordshire, the lower part of the Bathonian Stage is represented by the Chipping Norton Formation, the Sharp's Hill Formation (with the Stonesfield Member locally at the base) and the Taynton Limestone Formation. During the deposition of the Chipping Norton Formation, high energy carbonates were formed on a swell which followed the line of the Bajocian Moreton in Marsh swell. In a basin to the east of the swell carbonates were diluted with clastics. which entered from the east and south-east as coastal sediments derived from the London platform. Mobile substrates in this eastern basin are reflected in low diversity faunas consisting primarily of Liostrea, Aequipecten and Entolium . Highly mobile substrates are also correlated with similar low diversity faunas on the swell. In a second basin west of the swell, carbonates interdigitate with clays of the Lower Fuller's Earth Formation, where benthonic faunas include Liostrea and many other bivalves (both epifaunal and infaunal). The clays of the Sharp's Hill Formation, which succeed the sands of the Chipping Norton Formation over much of the eastern basin, suggest a deepening of the water coupled with a marine transgression over the source area of the sands. These clays have a relatively diverse marine benthos including bivalves, gastropods, corals, echinoids and rhynchonellids, which reflect slower rates of sedimentation and increased substrate stability. Locally (around Stonesfield in the eastern basin, and Stow-on-the-Wold in the western basin) this transgression is marked by silty beds of the Stonesfield Member, which accumulated in topographic lows as abnormally condensed mixtures of redistributed terrestrial and marine faunas and sediments. Elsewhere, the early phase of the transgression resulted in non-deposition and the development of hardgrounds capping the Chipping Norton Formation. Eventually, transgression over the London platform progressed to such a stage that clastics were no longer derived, but instead this new area of shallows became the main area of carbonate formation. The limestones of the Taynton Formation were derived during the culminating phase of the transgressive episode from this part of the London platform.

On predation of pelagic larvae and early juveniles of marine bottom invertebrates by adult benthic invertebrates and their passing alive through their predators

The dynamic quantitative balance between prey and predator invertebrate species inhabiting the same shallow-shelf (sublittoral level bottom) benthic communities was first discussed by Thorson (1953). Thorson considered the exact timing of larval settlement of prey and predator species possessing pelagic development and temporal supression of the adult predators' feeding activities during reproduction at the time of the preys' settlement to constitute the major factors which facilitate survival of the prey species in such communities. However, information obtained demonstrates that Thorson's “mechanism of balance between predator and prey species of benthic communities” is not always effective in securing survival from predation not only of the prey's spat but even sometimes of the predator's spat also. Because of this, the “mechanism” can not be rated as universally effective in all situations. Analysis of the data so far published demonstrates that, in marine benthic communities, especially in shallow-shelf waters, it is not uncommon for gametes, larvae, or early juveniles of different prey species to pass alive through suspension (filter)-feeding and deposit-feeding adult invertebrates preying on them. Sometimes development can even continue after excretion by predators. The hypothesis of Voskresensky (1948) and Goycher (1949) of the importance of this phenomenon for the maintenance and recruitment of the mussel Mytilus edulis and other filter-feeding lamellibranchs of nearshore waters preying on their own and other lamellibranch pelagic larvae must be rejected on the basis of accumulated data on their feeding and general biology and on the adverse influence of the mucous of their faecal pellets and pseudofaeces on the larvae excreted by them alive. The data considered here demonstrate that, although the passing alive of larvae and spat of benthic invertebrates through benthic predators is not uncommon in shallow-shelf bottom-communities, it plays no important role in the processes of maintenance and recruitment of the species and communities involved nor of the marine benthos as a whole. The actual ecological significance of predation on pelagic larvae and bottom spat of benthic invertebrate prey species by all three main trophic groups of marine benthos (suspension or filter-feeders, deposit-feeders, carnivores) and its importance to predator-prey dynamics in marine benthic communities remains open to debate until more reliable quantitative data become available.

BOOK REVIEWS

AQUARIUM FISHES, THEIR BEAUTY, HISTORY AND CARE. Photographs by Douglas Faulkner. Text by James W. Atz.DISEASES OF FISH edited by S. F. Snieszko and H. R. Axelrod.DISEASES OF FISH edited by S. F. Snieszko and H. R.IBP HANDBOOK NO. 16. METHODS FOR THE STUDY OF MARINE BENTHOS edited by N. A. Holme and A. D. Mclntyre.METHODS IN AQUATIC MICROBIOLOGY by A. G. Rodina. Edited, translated and revised by R. R. Colwell and M. S. Zambruski.OCEANOGRAPHY‐Readings from Scientific American edited by J. Robert Moore.ADVANCES IN ECOLOGICAL RESEARCH edited by J. B. Cragg.GROWTH AND ECOLOGY OF FISH POPULATIONS by A. H. Weatherley

A Photographic Method for Recording the Underwater Distribution of Marine Benthic Organisms

In recent years the development of SCUBA? diving has provided a new tool for the marine biologist (Parker 1966). Prior to the introduction of SCUBA, marine studies involved sampling by grab or trawl, occasionally by helmet diving (Kitching, Macan & Gilson 1934), or by observation with surface controlled cameras, including television (Barnes 1963). Diving techniques are proving particularly useful in areas inaccessible to surface probing, such as under rock overhangs and in sub-littoral caves and canyons. Although many studies using SCUBA have been carried out in northern waters (e.g. Forster 1955; Kain 1960, 1962), the main developments have occurred in warmer seas, including the Mediterranean (e.g. Molinier & Picard 1952; Molinier 1960; Peres 1967). One important problem facing workers employing diving methods is the establishment of suitable quantitative sampling procedures. Conventional techniques of the land ecologist, including quadrat analysis, are frequently employed and semi-quantitative methods such as modifications of the plant sociological techniques of the ZurichMontpellier school (Braun-Blanquet & Pavillard 1925) have provided useful information about the Mediterranean marine benthos (Molinier & Picard 1952; Molinier 1960). One further difficulty encountered in underwater studies is the short duration of work possible with the diving equipment available. However, technical developments under way at present should help to reduce this problem, such as the introduction of liquid-air breathing equipment (Tzimoulis 1967) and the construction of underwater laboratories and vehicles (Rechnitzer 1965; Valery 1967). Although it will be some time before these developments are available to the average marine ecologist, they will permit work in excess of 300 m and underwater projects lasting weeks or even months. The investigation described was part of a study of techniques aimed at making the maximum use of time spent in surveys underwater, and its basis was a rapid but precise photographic recording underwater, leaving the time-consuming problem of measurement and calculation to the laboratory. The techniques described were employed to survey the physical features of small areas of the sea-bed for the preparation of maps and profiles; to plot the distribution and cover of particular species; and to follow the movement of selected species of mollusc and echinoderm, during a biological survey of the marine benthos in the eastern Canary Islands. Although underwater photography has proved extremely valuable in qualitative investigations, it has seldom been used in quantitative work. Photogrammetry has been employed by cartographers for many years, particularly in map construction from aerial survey data, but normally it requires complex, bulky equipment and can be attempted

Isolation of Organic Solutes from Sea Water by Co-precipitation

DURING an investigation of the trophic relationships of the marine benthos, attempts have been made to isolate and identify the organic solutes in sea water. These have been generally defined as constituents which pass a membrane of pore size 0.45µ. A discussion of the most likely solutes and a list of those so far found have been provided by Duursma1, and methods for their isolation have been reviewed by Hood2 and Riley3. Practical comparison of various methods has led us to conclude that the co-precipitation method is potentially the most versatile, is convenient and has the added advantage of requiring only mild operating conditions.

Adaptations and life habits of devonian atrypid brachiopods

Atrypid brachiopods, which are shallow marine benthos, anchored, stabilized or affixed themselves to the muddy substrate or to host objects on the sea floor by several alternative means: a well-developed pedicle muscle, frilly or spinous projections on the shell surface or modifications of shell shape. Atrypid taxa may show different, but functionally comparable adaptations to the same restricted environment, or show identical specializations of one character in the same biotope. Most, if not all sedentary atrypid species appear to have been oriented in a brachial valve upwards position in mature stages of growth.

Commotion in the ocean: the growth of continents and ocean basins : Dietz Robert S., 1964. In: Studies on Oceanography dedicated to Professor Hidaka in Commemoration of his Sixtieth Birthday, 465–478

A calcareous sandstone sequence that forms part of the Eze-Aku Formation (Reyment) features an assemblage of ichnofossils in a section exposed on a quarry face. The traces encountered include horizontal burrows, some of which are preserved as casts, lined with organic matter and belonging to the ichnogenera Gyrolithes, Pholeus and Arthrophycus. Three other types of trace fossils are described as horizontal crawling trails, flat impressions and cylindrical shafts without formal names. Gyrolithes are by far the dominant traces in this sequence. The degree of bioturbation is high in every horizon. Body fossils are very rare except for scattered occurrence of fragments of calcitic pelecypod shells.Ichnological and lithological considerations suggest that the sediments were deposited in an aerated shallow shelf environment which supported an assemblage of decapods, worms and other shallow water marine benthos. Deposition was generally below wave base under a continuous but relatively slow rate of sedimentation.

The use of trawl, grab and camera in estimating marine benthos

Certain animals of the epifauna, because of their distribution over the bottom, are often difficult to sample quantitatively. They may occur as individuals widely dispersed over a large area, or they may be present in dense aggregations which themselves have a patchy distribution. In the past, workers have tried to estimate the numbers of such animals by the combined use of trawls and grabs of various types. The post-war development of underwater photography suggests that the camera will be a useful additional tool (e.g. Vevers, 1951, 1952). During the testing of an underwater camera from Aberdeen an opportunity was taken to compare the estimates of some of the larger epifauna from grab and trawl hauls with estimates derived from underwater photographs. The results are described in this paper.

Marine Biological Research in Great Britain

WE have read with interest Prof. F. E. Fritsch's letter on marine biological research in Great Britain1, in which he stresses the need for the co-operation of botanists and zoologists in the investigation especially of marine benthos and refers to the difficulties and limitations experienced by investigators in universities at a distance from the sea.