Littoral Ecology Research Articles

Late Cretaceous neornithine from Europe illuminates the origins of crown birds.

Our understanding of the earliest stages of crown bird evolution is hindered by an exceedingly sparseavian fossil record from the Mesozoic era. The most ancient phylogenetic divergences among crown birds are known to have occurred in the Cretaceous period1-3, but stem-lineage representatives of the deepest subclades of crown birds-Palaeognathae (ostriches and kin), Galloanserae (landfowl and waterfowl) and Neoaves (all other extant birds)-are unknown from the Mesozoic era. As a result, key questions related to the ecology4,5, biogeography3,6,7 and divergence times1,8-10 of ancestral crown birds remain unanswered. Here we report a new Mesozoic fossil that occupies a position close to the last common ancestor of Galloanserae and fills a key phylogenetic gap in the early evolutionary history of crown birds10,11. Asteriornis maastrichtensis, gen. et sp. nov., from the Maastrichtian age of Belgium (66.8-66.7 million years ago), is represented by a nearly complete, three-dimensionally preserved skull and associated postcranial elements. The fossil represents one of the only well-supported crown birds from the Mesozoic era12, and is the first Mesozoic crown bird with well-represented cranial remains. Asteriornis maastrichtensis exhibits a previously undocumented combination of galliform (landfowl)-like and anseriform (waterfowl)-like features, and its presence alongside a previously reported Ichthyornis-like taxon from the same locality13 provides direct evidence of the co-occurrence of crown birds and avialan stem birds. Its occurrence in the Northern Hemisphere challenges biogeographical hypotheses of a Gondwanan origin of crown birds3, and its relatively small size and possible littoral ecology may corroborate proposed ecological filters4,5,9 that influenced the persistence of crown birds through the end-Cretaceous mass extinction.

A Contribution to the Littoral Ecology of Liberia

A Contribution to the Littoral Ecology of Liberia

The hydrology of the coastal waters of Hong Kong

A detailed hydrological survey of the coastal waters of Hong Kong has been undertaken over a period of 12 months from 1972–1973. Five sites transecting Hong Kong from north-west to south-east and anticipated as representing typically oceanic and very exposed conditions in the southeast and a sheltered, estuarine environment in the northwest with stations of intermediate hydrology between were selected for study. A number of important hydrological parameters (i.e. actual water temperature, monthly minimum and maximum water temperatures, salinity, chlorinity, conductivity, pH, dissolved oxygen, biological oxygen demand, inorganic phosphate, nitratenitrite, reactive silicate and calcium) have been taken into account. These hydrological parameters were measured three times each month from the surface and bottom waters of the five sites. Two additional surveys were carried out at the most northwesterly site, in winter and summer, respectively, in which the variations in salinity, conductivity, water temperature, and pH of the surface waters were recorded hourly for 24 hours. The spatial and the seasonal variations in the levels of these hydrological parameters have been discussed and further related to local pollution levels as well as to the seasonal influx of fresh water from the Pearl river. These two factors are, it is considered, the most important elements influencing the coastal hydrology of Hong Kong and thus the littoral ecology.

A Surface-Active Chemical System for Controlling and Recovering Spilled Oil from the Ocean

A system involving the use of a surface-tension modifier is feasible for controlling and recovering oil spilled on the ocean in a wide range of weather conditions. Tests have led to the conclusion that the chemicals are less harmful to the ecology than are the oils they help to recover. Introduction In the past, oil-spill containment and recovery under severe weather conditions has been achieved with only marginal success. It is generally accepted now that the effectiveness of existing mechanical booms is limited to wave heights under 4 ft and current velocities under 1 knot. Severe wave and wind action has generally caused mechanical failure of the booms. In those instances when booms have been effective in containing oil, wave action was not significant. The objective of the research reported here has been to evolve a system for oil-slick control and oil recovery that would be largely independent of the limitations that weather imposes on mechanical containment devices and on most existing oil recovery devices. The constraints placed upon the system were that it be effective under severe weather conditions and that it be highly mobile, preferably air transportable. The system that has evolved and that is reviewed here consists of the following: Oil-slick control by means of surface-activechemical agents that possess spreading forcesgreater than those of most oils. The surfacechemical agent prevents the spreading of oil onwater and in most cases causes an oil slick tocontract so as to occupy a much smaller areaof water surface. Generation and spreading of an open-cell, flexible polyurethane foam at the site of the spill. Pick-up of the oil-soaked polyurethane foam byeasily transportable net booms or by ship trawlsor purse seins. All pick-up activity is to behandled by marine equipment that generally isavailable in the coastal regions of the U. S. Extensive research has been conducted on surface-active chemicals and their effects on various types of oil under a variety of weather conditions. The toxicity of one of the most effective of these chemicals to the marine and littoral ecology has also been investigated. Development work has been done on ways of generating and spreading foam, using boats or helicopters. Work has also been performed on net booms for recovering foam, on a squeezing technique for regenerating the foam, and on a system for ultimately disposing of it. Oil-Slick Control Spreading of Oil on Water Cochran and Scott and others discussed at length the spreading of oil on water. After the initial spreading period in which gravitational forces play a large part, the only important force tending to cause the oil to spread is surface tension. Thin oil slicks tend to spread on water in response to the force imbalance shown schematically in Fig. 1. Three forces operate on an oil slick: the surface tension of water, w, which tends to spread the oil on the surface of the water; the surface tension of the oil, o, and the interfacial tension between the oil and the water ow. Both o and ow tend to cause the oil droplets or slick to contract upon itself. JPT P. 255

The Littoral Ecology of Rocky Parts of the North-Western Shore of the Guinea Coast

The Littoral Ecology of Rocky Parts of the North-Western Shore of the Guinea Coast

Some Aspects of Littoral Ecology: the Parameters of the Environment, their Measurement; Competition, Interaction and Productivity

Some Aspects of Littoral Ecology: the Parameters of the Environment, their Measurement; Competition, Interaction and Productivity

Littoral ecology and biogeography of the southern oceans

This contribution is concerned with the littoral ecology and biogeography of the southern oceans, and at the outset I would like to define its scope. I have used the term littoral in a broad sense, to include all those zones (supralittoral, intertidal or true littoral, and sub-littoral) between the lower limit of the land vegetation and the lower limit of algal growth. Attention will be concentrated on the southern cold-temperate zone, which is also broadly defined in view of the varying limits which have been placed on it according to the bases used; oceanographic, faunistic or floristic. Adjoining antarctic and warm temperate zones are discussed where relevant. The following account is based on personal experience of the greater part of the New Zealand coastline, the Chatham Islands and the west coast of South America from Montemar near Valparaiso to Isla Hermite in the Cape Horn group. All these regions have been studied intensively. Brief visits have also been paid to shores in Peru, in New South Wales near Sydney, and in South Australia.

VII.—On Migrations ofLymnœa peregra(Müller) on the Shores of Loch Lomond

SynopsisSeasonal changes in the distribution ofLymnœa peregra(Müller) on a gently sloping beach of Loch Lomond have been studied in detail, with particular reference to the effects of the changes in water level which occur. At lower water temperatures the distribution can be correlated with the availability of food. At higher water temperatures the respiratory needs of adult snails cause them to remain close to the water's edge, even in the absence of food. This is not always true of young snails. Measurement of the fæces produced by such adult snails gives further evidence that a degree of starvation can occur for short periods in the summer months.Comparative data on the characteristics of the physical environment and the general distribution of gastropods in Loch Lomond are given, and the study discussed in relation to previous work on the littoral ecology of large lakes.

Investigations on the microfauna inhabiting seaweeds on rocky coasts (Untersuchungen über die algenbewohnende Mikrofauna mariner Hartböden). IV. Studies on the vertical distribution of the fauna inhabiting seaweeds below the Plymouth Laboratory

The present study forms part of a more extensive one on the ecological factors which govern the distribution of the microfauna inhabiting seaweeds on rocky sea-coasts. This part of marine ecology is lagging far behind other branches. I wish to stress two points in particular: fasirst, that our understanding of the composition of the littoral (intertidal) fauna would increase very much if this fauna can be linked with the true infralittoral fauna, and, secondly, problems involving the synecological aspects of marine biology cannot be approached before more is known about the autecology of the animals composing the cryptofauna (i.e. those living in the shelter of algae) and the causal factors determining their occurrence and distribution within a given area under stated conditions. On this point the work of T. A. Stephenson is especially relevant: as a result of his extensive investigations on the composition of the intertidal flora and macrofauna he has come to stress the importance of autecological rather than of biocenological work on the shore (Stephenson et al. 1942; Stephenson, T. A. & A., 1949). Moreover, he has clarified the intertidal terminology and introduced the most useful terms “supra-” and ‘infralittoral fringe”. Since his terminology appears to be the best suited to meet the needs of ecologists, I hope it will be generally applied in future. Most work on littoral ecology has been limited to macro-organisms, valuable data on the ecology of microfaunas of seaweeds have been supplied by Colman (1940), Kitching, Macan & Gilson (1934), and Dahl (1948).