Littoral Forms Research Articles

The postglacial diatom history of Sunfish Lake, southwestern Ontario

An investigation was made of the diatom stratigraphy in a sediment core from Sunfish Lake, a small (8.3 ha), deep (20 m), meromictic lake in southwestern Ontario. About 340 diatom species and varieties distributed among 37 genera were identified from the sediments; however, only 16 taxa had more than 2% representation in any sample. On the whole, the number of individuals and diversity of the samples increase over the postglacial period. Diatoms first appear in pollen zone A and consist mainly of the littoral forms Cymbella diluviana, Fragilaria lapponica, and F. construens var. venter. It is suggested that these taxa are typical of early postglacial lacustrine sediments in northeastern North America. Cyclotella bodanica first appears in zone B and is dominant in most samples throughout the core. It is euplanktonic and typical of subalpine, circumneutral, oligotrophic lakes. In C2, when the climate was possibly warmer and drier than present, there is evidence for a lower lake level: C. bodanica is temporarily replaced in importance in the sediments by C. kuetzingiana and the proportion of littoral and epiphytic diatoms increases. Cyclotella bodanica regains its former importance in C3 sediments with the possible return to a cooler, wetter climate. About 850 years before present (B.P.) the lake evidently became eutrophic. Cyclotella bodanica declines and there is an increase in the proportion of several species typical of a higher trophic level, e.g., Stephanodiscus hantzschii, Cyclotella glomerata, and several Synedra spp. The cause is unknown. The lake probably became meromictic about 140 B.P. at a time when the forest was cleared and agriculture began in the watershed.

The Cladocera of Ontario with remarks on some species and distribution

The Cladocera of Ontario were studied from material collected over a wide geographical area. In all 244 lakes and 33 ponds were sampled, some of them more than once.A method for making stained permanent preparations of Cladocera used in our study is described.The genus Daphnia is richly represented. Based on a study of this material we have raised Daphnia pulicaria Forbes from synonymy in the North American fauna. The common limnetic species have been demarcated more satisfactorily. A hitherto undescribed Daphnia species was recorded. Some systematic notes are also included on species of the genera Diaphanosoma, Ceriodaphnia, Eubosmina, and Bosmina.Seventy species of Cladocera were recorded in the present study. This brings the species recorded from Ontario to 78 species; 26 species are recorded from Ontario for the first time. While the limnetic species presently known probably represent a complete list many littoral forms have certainly not been recorded so far.The distribution of the various species in the different parts of Ontario is given. The relative frequency and dominance of species is discussed.

Danish Chydorid Cladocera: Modern Ecology and Core Studies

Surficial sediments from 77 Danish lakes were processed for chydorid remains for the purpose of establishing relationships of species occurrence to lake type. A total of 35 species of chydorids was recovered; 3 species were new for Denmark, while 3 others previously reported from Danish lakes were not found. The lakes sampled were subjectively grouped according to physical—chemical measurements into 1 of 3 groups–clear—water lakes (1), ponds and bogs (2) and polluted, clear—water lakes (3). Correlations between chydorids and chemical—physical properties of lakes, plus evidence from relative abundances and frequencies of each species found in each lake type, suggests that most species prefer those waters best termed oligotrophic and dystrophic. The exceptions of Chydorus sphaericus and Alona rectangula which, when found in high percentages, typify eutrophic or polluted sites. These data correlated well with species diversity values–high values were found in clear—water lakes (1) and ponds and bogs (2), while low diversities were typical of polluted sites (3). These data suggested that species diversity is a function of available habitat (rooted aquatics), and hence to a large extent the distribution of most chydorid species within a region is determined by habitat diversity (structure). Grane Langso (an oligotrophic, Jutlandic lake) and Esrom S° (an eutrophic, Zealandic lake) were selected for paleo—studies because of their differences, which resulted in contrasting lake development. Postglacial gyttja sediment in Grane Langso extended to 431 cm below the mud—water surface interface. Pollen zonation, and a radiocarbon date of ±9500 BP placed the lowest organic deposits into Pre—Boreal time. Two chydorid species were important in Grane Langso Late—glacial sands underlying the gyttja (Alona affinis and Chydorus sphaericus). Chydorid faunas developed through the Pre—Boreal and early Boreal; by late Boreal chydorid populations were most diverse, and presumably stable. A decrease in species diversity during Atlantic time was due to unstable conditions within the lake, evidenced by deposition of sand; Chydorus piger was abundant during this period. Sub—Boreal organic deposits overlay the Atlantic sands. High percentages of Pleuroxus during mid—Sub—Boreal were attributed to man's activity, and a lower water level. The most recent change in chydorid assemblages occurred within the past 100 yrs; this change was increased percentages of Alonella nana–a species normally associated with low alkalinities in Denmark. Postglacial calcareous gyttja deposits in Esrom So extended to 380 cm below the mud water interface. Calcareous clay extended from 381—840 cm, and glacial till occurred below 840 cm. Pollen preservation was poor in Esrom, but the lowermost gyttja was probably Pre—Boreal (Zone IV). No pollen counts were attributable to Zone VI. Few chydorid remains were found in Late—glacial clays, and extensive development of populations began in Pre—Boreal time (370 cm). Chydorid assemblages characteristic of discriminant Group 1 were present throughout most of the postglacial deposits; benthic species were prevalent during most of the lake's history. Littoral forms did increase in Sub—Boreal time, but by Sub—Atlantic chydorid assemblages were again dominated by benthic groups. In Esrom, postglacial chydorid fluctuations were dampened by its morphological and chemical characteristics, while Grane Langso fossil assemblages were sensitive to minor variations in the lake's environs. Pioneer chydorid species in northern Europe are Chydorus sphaericus, Alona affinis, A. quadrangularis, Acroperus harpae, and Alonella nana.

Les alluvions littorales quaternaires de la cote landaise meridionale

Abstract A Flandrian [Quaternary] marine terrace forms the coastal zone between Biarritz and Hossegor [west coast of France]. It is bordered on the east, between the Adour and Ondres, by Pliocene hills, but farther north, next to outcrops of the Landes sands, by typical parabolic dunes. This terrace, averaging 2 km in width and 20 to 30 m in thickness, rests on a Tertiary substratum. It is composed of sands, gravels, and small pebbles as well as fluviomarine silts. The macrofauna recovered comprises modern littoral forms. Post-Flandrian eolian deposits cover it.

The effects of the winter of 1962/63 on the british marine fauna

1. During the exceptionally cold winter of 1962/63 the south east coasts of Great Britain suffered the coldest conditions, but the coasts of Hampshire and Dorset, the Bristol Channel and parts of North Wales the greatest negative anomalies. 2. Northern forms were not generally seriously affected, but some Celtic and southern forms suffered very high mortality in the intertidal zone, particularly in embayed situations in the areas mentioned above. 3. Southern forms limited to exposed western promontories did not suffer much damage; marine algae were also little affected. 4. Death was caused, not only as a direct result of exposure of the tissues to extreme cold, but also from the general lowering of the animals' activity; for example, failure to remove silt by ciliary action, to cling to rock surface, and to burrow, led to many deaths. 5. Even where high mortality was experienced, a few, perhaps more resistant, individuals of the species generally survived in favourable habitats, so that distribution limits were little affected. Adaptive behaviour played an important part in the survival of many littoral forms.

First Record of a Hawaiian Shore Bopyrid (Isopoda : Bopyridae)

A shore bopyrid (epicaridean isopods parasitic upon Decapoda) was found in 1962 in the left branchial region of the crab Xantho crassinianus at Diamond Head, Oahu, Hawaii. Although the larvae and male were well preserved, the female had been damaged and several critical parts were missing. Bopyrids have not been intensively studied in the United States in the last 50 years, and there is a total absence of records of littoral forms for the Hawaiian Islands. Two deep-water bopyrids (Entophilus omnitectus and Scyracepon hawaiiensis) have been previously reported from the bottom of inter-island channels, yet neither is in the same genus as this shore form. The new specimen is clearly an Ione or a Cepon, but further identification cannot be made due to the absence of pleopods and uropods. It is hoped that anyone finding additional specimens will send them to the writer, so that this new genus and species for the Hawaiian Islands may be more fully described and named. Through the courtesy of Dr. Albert Tester, Chairman, Department of Zoology, University of Hawaii, the writer was given a bopyrid specimen which students G. Habagama and J. Shoup had preserved from a collecting trip to tide pools at Diamond Head, Oahu, Hawaii, on 13 January 1962. The parasite was found in the left gill area of the small shore crab, Xantho crassimanus Milne Edwards. The branchial swelling contained an adult female, the accompanying male, and many epicaridian larvae (Fig. 4). The posterior portion, and several of the pleural plates of the female were damaged or missing, but the male and the larvae were intact. No additional evidence of bopyrids was seen along the shores of any of the main Hawaiian islands, despite several months of field work in the summer of 1962. The male, larvae, and damaged female specimens forming the basis of this paper have been deposited in the U. S. National Museum collections, catalog numbers: 110190 (male), 110191 (female), 110192 (larvae).

Algal classification—An aid to improved industrial utilization

Significant commercial exploitation of some of our most primitive plant forms, the marine algae, is a relatively recent development. Records, rumor, and folklore particularly from the Orient provide evidences of sea plant utilization back into the shadows of history. For the most part, these uses involved the gross plant structure as a food or food accessory and even as today it is the macroscopic algal forms that were favored. The mass of easily harvested wild forms predominate in two Divisions, the Rhodophyta and Phaeophyta. Direct use of sea plants as food involves many more types than any other application. Shore dwellers have probably, at one time or another, tried every likely looking plant, and even some not so likely looking, as an addition to the pot. Tabulation of those that at one time or another have graced local produee markets includes members of the red, brown, and green algae involving 195 species in 76 genera. The red and brown sea plants predominate as one would expect from their usual size. Only in the Orient where the peoples have the proper combination of patience and palate does a sizable market still exist. It is also in the Orient that the closest approach is reached to sea plant cultivation, where artificial obstacles are placed to support increased natural growths of Porphyra tenera. Farmers along the shore have probably always used drift weed and littoral forms, predominantly rockweeds and Laminariales, for soil conditioning or manuring, and stock feed supplements. At one time when kelp burning for iodine recovery was an important industry, the French government was compelled to control this seashore resource so as to provide an

Crustacea Aus Dem Amazonasgebiet, Gesammelt Von Professor Dr. H. Sioli Und Dr. R. Braun. 1. Litorale Und Substratgebundene Cyclopoida Gnathostoma (Copepoda)

From 56 samples, taken by Professor Dr. H. Sioli, Plon, and Dr. R. Braun, Zurich, in the Amazon River region in the years 1940-1953, a list of Cyclopoida Gnathostoma is given. These are littoral forms associated with the substratum. Among 14 species there are two new species, three new subspecies and one new form, which are described and figured. Three previously known species are also characterized morphologically.

Spigolatute di critica sopra la posizione sistematica di alcuni Crostacei Isopodi terrestri

Summary It is shown that genus Olibrinus Budde-Lund (1912) cannot be assigned to the family Oniseidae owing to the enunciated features and the figures which illustrate the description. The institution - established by Vandel (1952) - of a new subfamily, belonging to the above mentioned family, becomes more unacceptable if Vandel attribute his new genus Adonis (1955) to the Olibrininae. Just on ac-count of the description given by Vandel, Adonis cannot at all be considered allied to Olibrinus. To demonstrate the unlikeness between Olibrinus and Adonis suffiee, it to say that they were collected in completely different conditions, being the former a littoral form, the latter a subterranean one. Olibrinus and Adonis must be considered as unrelated forms, whose Systematic. position has not yet been defined. It is not possible to accept without reserve the conclusions of Vandel (1952). In bis opinion the austral Trichoniscidae must be considered as a quite destinet family named Styloniscidae. But both deseript...

Experiments on the Selection of Algal Substrates by Polyzoan Larvae

ABSTRACT Many species of Polyzoa show marked specificity with regard to the substrate on which they occur. Epiphytic forms are often found mainly on one species of alga. Experiments were performed in which a number of algal species were offered to polyzoan larvae as substrates for settlement. The disposition of algae, and the dishes containing them, was such that the layout conformed to a Youden Square design. This not only achieved economy of materials, but ensured a balanced experiment, made possible a statistical analysis of the results, and eliminated any possible effects of extraneous environmental factors. The larvae showed marked substrate preferences when settling. In the littoral forms Alcyonidium hirsutum, A. polyoum and Flustrellidra hispida, the selection of algae accorded closely with their observed natural distributions: in each case highest settlement took place on Fucus serratus. It seems probable that positive selection plays an important role in determining the distribution of these species on the shore. Celleporella hycdina larvae were also selective, but the preferences were less clearly related to the ecological distribution of the adult. Surface texture appears more important than contour as a factor influencing the choice made by larvae between algal substrates, although the physical and/or chemical factors responsible for the observed differences in attractiveness of algae are largely unknown. However, it is evident that the nature of the surface alters with age, and that this influences favourability. The presence of mucus has an adverse effect on settlement. Once the actual substrate has been chosen, the larvae respond to surface contour and, if possible, select a groove or concavity as a site for fixation.

Vitamin a in the Invertebrates

Vitamin a in the Invertebrates

Influence of Certain Substances on the Fluidity of the Cytoplasm and the Fertilizability of the Egg of the Sea-urchin, Psammechinus miliaris

ABSTRACT After nuclear maturation the eggs of Psammechinus (Ps.) miliaris are still ‘underripe’ with respect to their cytoplasm. This phenomenon is particularly conspicuous in Ps. miliaris from the Swedish west coast (see, for a summary, Runnström, 1949). In the small individuals of Ps. miliaris dredged from a depth of 30–40 metres this state of underripeness may last for months, so that full cytoplasmic maturity may be reached only in the latter half of August (Lindahl & Runnström, 1929). The littoral form of Ps. miliaris, on the other hand, has already attained cytoplasmic maturity in the latter half of June. Temperature conditions evidently play a decisive role in the phenomenon.

The Body Temperature of Woodlice

ABSTRACT Measurements by means of thermocouples, accurate to 0.1° C., were made of the body temperature of the woodlice Armadillidium, Porcellio, Oniscus and Ligia, and of the cockroach Blatta, both alive and dead, in a stream of saturated or dry air at both 20 and 37° C. No difference in temperature depression was found between living and dead woodlice, and in all the animals used there was, after equilibration, no difference greater than 0.1° C. between the air temperature and body temperature if the air were saturated with water vapour. In dry air, the body temperature of all the animals except Ligia settled down after at most 25 min. to a steady temperature which was lower than that of the surrounding air. The body temperature of Ligia continued to rise slowly for at least 2 hr., though remaining well below that of the environment. After 30 min. in dry air at 20 and 37° C. respectively, mean temperature depressions (of at least three readings at each temperature for each species) were, in degrees centigrade: Ligia, 2·6 and 6·8; Oniscus, 1·5 and 2·7; Porcellio, 0·4 and 1·3; Armadillidium, 0·5 and 1·8; and the cockroach Blatta, 0.7 and 2.4. The order of the Certain anomalies which appear when these figures are compared with previously established figures for insects are probably the result of differences in permeability of the integument and in the site of water loss. The ability to evaporate water rapidly, and thus to cool the body, may be of survival value when woodlice are exposed to high temperatures for short periods, particularly in littoral forms which may well have been intermediate in the evolution of terricolous from maricolous isopods.

Some Pycnogonids Found Off the Coast of Southern California

Few collections of Pycnogonids from the offshore waters of California have been made, and this paper is the first detailed account of some of the species from that region although several of the collections were made as long ago as 1915. For the material discussed in this paper I wish to thank Mr. Percy S. Barnhart, Curator of the Museum of the Scripps Institution of Oceanography, who loaned me a collection gathered over a period of years, and Dr. George S. Myers of Stanford University for the Pycnogonids dredged during the Crocker-Stanford Expedition on the Zaca off the coast of southern California in September, 1938. I am also indebted to Dr. Carl D. Duncan of San Jose State Teachers College, Dr. G. E. MacGinitie, Director of the Kerckhoff Laboratories of the California Institute of Technology at Corona Del Mar, and Mr. E. F. Ricketts of the Pacific Biological Laboratories at Pacific Grove for specimens of Nymphopsis spinosissimus (Hall), and to Mr. H. V. M. Hall of Berkeley, California, for suggestions concerning the status of this species. Four species, two of them new, have been dredged from moderate depths in the general vicinity of the Santa Barbara Islands and Catalina Island. The most common species appears to be Nymphon solitarium Exline, described from Puget Sound, and of the 44 specimens in the two collections of dredged material, 26 are of this species. Anoplodactylus erectus Cole is next, represented by fourteen specimens. This is also a littoral form, found in tide pools and hydroid colonies on wharf pilings from Monterey Bay to San Diego. Additional data concerning its distribution will be found in the table of localities for Nymphon solitarium, below. The other two species, each represented by two specimens, are described below.

Biology of a Littoral Mite

DURING my work on the biology of the seashore in East Greenland1 I made some biological observations of the large, bright red littoral mite (Molgus littoralis L.) ; its distribution is almost circumpolar, especially on the shores of the more northern regions. In East Greenland it was commonly met with on the shore, but extending its domain beyond the shore, being found (also the eggs) up to an altitude of 120 m., most often in sandy and gravelly places. Trägårdh (p. 4192) has recorded this and explains it by the non-occurrence of big competing mites. In southern Spitsbergen, it seems to be a strictly littoral form ; but in northern Spitsbergen (Low Island, c. lat. 80° N. ; Hinlopen Strait) it also extends to the ” fj” ldmark”, which is beyond the shore (Summerhayes and Elton, p. 250)3.

Pelagic Nemerteans1

THE power of progressing through the water by swimming has long been known in the nemerteans; thus Nardo mentions it in Cerebratulus marginatus, Grube in Meckelia aurantiaca, De Quafages in Polio, bembix, whilst more recently it has been described in Amphiporus pulcher Q.F.M. A. (Drephanophorus) spectabilitis De Micrura fusca, McI., and Tetrastemng, Abild. But the first truly pelagic nemertean was only brought into notice by Prof. Moseley during the voyage of the Challenger (1875). Now, through the labours of Hubrecht, Verrill, Craven and Heath, Brinkmann, Joubin, Gerarda Stiasny-Wijnhoff, and others, a long list of species from all the great oceans, except perhaps the Antarctic, demonstrates their wide distribution, though they are always thinly scattered, so that, as regards some, only one sex is known. Moreover, whilst the littoral nemerteans as a rule form two marked groups of the Enopla and the Anopla (the armed, with the mouth in front of the ganglia, and the unarmed, with the mouth behind the ganglia), the pelagic forms fall under a section of the armed. They are further distinguished by their comparatively short, flattened, and, in some, translucent bodies, the walls of which are in marked contrast to the firmer tissues of the littoral forms, for the almost gelatinous parenchyma is largely developed. Further, some possess a caudal fin, and a few, in addition, a lateral fin. The dorsal and the ventral longitudinal muscles with vertical bands are best developed. Eyes are often absent and sense organs few and peculiarly modified. The typical proboscis and its sheath, with the armature of the former leaning to that in Drephanophorus, is present, though no mention is made by either Prof. Brinkmann or the present author of the remarkable corpusculated fluid in its sheath. Moreover, the males of the pelagic group carry their spermaries in the cephalic region with or without penes, whilst the females follow the littoral nemerteans in having the ovaries arranged along the body—in this case interdigi-tating with the alimentary cseca. Lastly, some males are provided with a pair of muscular tentacles anteriorly.

Trematode Parasites from Food-Fishes of the North Sea

The following observations were made in September, 1908, during a short residence at Aberdeen where, through the kindness of Prof. J. Arthur Thomson, I was able to deal with a considerable number of fishes in the very limited time at my disposal1. The investigation was intended as a continuation of that already carried out at St Andrews, the object being to examine a number of fishes which could not readily be obtained at the latter place. There the fishes dealt with were mostly littoral forms, but at Aberdeen attention was mainly paid to the larger deep-water fish; of these a plentiful supply could be easily obtained. A few species were re-examined here.

The systematic position of the genus Fossarina, A. Adams and Angas, and of Fossarina varia, Hutton

Some time ago I found that Fossarina patula, Adams and Angas, had a rhipidoglossate dentition and a multispiral operculum. I mentioned the discovery to: Mr. Hedley, and he at once drew my attention to the genus Minos, Hutton, and gave me dried specimens of the type (M. petterdi, Crosse), and of Fossarina varia, Hutton. The examination of these has been productive of rather curious results. The genus Fossarina was described by A. Adams and Angas in 1863, their type being F. patula, from Sydney Harbour. A short description of the shell is followed by the statement, "Operculum corneum, subspirale," and "this genus constitutes a peculiar littoral form allied to.Fossar, from which it differs in the curvature of the inner lip and circular aperture". It is also compared with.Conrdia, A. Ad., and.lsapis, A. Ad., and here I might draw the attention of those more fortunately placed than myself, to the fact that none of the six species of the former of these two genera have been figured. When dealing with the Japanese species (.Fossarina picta, A. Ad.), Dunker questioned the correctness of the systematic assignment of the species.

Report on the Tunicata of Plymouth

The southern shores of the English Channel have long been famous for the wealth of their Tunicate fauna, having furnished material in abundance for the classical researches of Milne-Edwards, Giard, and Lacaze-Duthiers. The Channel Islands also have been repeatedly visited by English zoologists, and have amply supplied those among them who have been in search of Tunicate treasures. Probably the peculiar tidal conditions of this part of the Channel are especially favourable to a rich development of littoral forms; but, as the work of Montagu, Couch, Clark, Alder, Gosse, Cocks, Bate, and Norman sufficiently testifies, the Devon and Cornish coasts of England can lay claim to an almost equally luxuriant shore fauna, the rocky bays and long sheltered estuaries being especially wealthy in this respect. During my residence at Plymouth I found that the Tunicata were among the best represented groups of the fauna, and, as I devoted considerable attention to the search for rare or new, as well as for well-known forms, I trust that a classified report upon the local representatives of the group will not be without its usefulness to other investigators.

XXVI. On the Rhizopodal Fauna of the Deep Sea

The Author commences by referring to the knowledge of the Rhizopodal Fauna of the Deep Sea which has been gradually acquired by the examination of specimens of the bottom brought up by the Sounding-apparatus; and states that whilst this method of investigation has made known the vast extent and diffusion of Foramimferal life at great depths,-especially in the case of Globigerina-mud , which has been proved to cover a large part of the bottom of the North Atlantic Ocean,—it has not added any new Generic types to those discoverable in comparatively shallow waters. With the exception of a few forms, which, like find their most congenial home, and attain their greatest development, at great depths, the general rule has seemed to be that Foramimfera are progressively dwarfed in proportion to increase of depth, as they are y a change from a warmer to a colder climate; those which are brought up from great depths in the Equatorial region bearing a much stronger resemblance to those of the colder-temperate, or even of the Arctic seas, than to the littoral forms of their own region.