Rocky Island Research Articles

A Critical Survey of Seaweed Diversity of Chilika Lake, India

During the last seventy years several studies have been undertaken on different aspects of marine algae from different parts of the Indian coast. The country has a vast coastline of more than 7,000 km, which harbours a large diversity of marine algal species. So far nearly seven hundred seventy species of marine algae have been reported from different parts of the Indian coast, which includes 184 species of Chlorophyceae, 166 species of Phaeophyceae and 420 species of Rhodophyceae (Sahoo et al. 2001). Although systematic studies on marine algal distribution and diversity are known from different coastal provinces of India, not much published information is available about the marine algal flora of Orissa. The state has a coastline of 460 km covering mostly sandy beaches. Sahoo (1989); Sahoo and Vijayraghvan (1986) reported occurrence of Centroceras clavulatum, Chaetomorpha antennina and Herposiphonia tenella from Gopalpur coast of Orissa. Reports of occurrence of some marine algal species have also been reported from Chilika, a brackish water lake in Orissa. Biswas (1932) in his monumental work reported nine different species of seaweeds from different parts of the lake. Parija and Parija (1947) studied the succession of some algae on a rocky island of the lake. Sahu and Adhikary (1999) reported only six marine algal species from some parts of the lake. Out of all these studies only Biswas gave a detailed authentic monograph on algal flora. But since Biswas’s study in 1932, the lake had undergone several ecological changes due to closing of the lake mouth to the sea thus blocking the entry of saline water to the lake. Besides, large-scale aquacultural activities have gone up in the lake during last several years. Eutrification has also caused several problems to the lake along with siltation. All these activities over the years have not only changed the ecological characters of the lake but also its floristic composition. Thus, the present study is an important step to re-evaluate the seaweeds diversity of the lake.

Selection often overrides the effects of random processes in island populations of Philaenus spumarius (Homoptera)

The influence of various evolutionary factors on the populations of the colour polymorphic meadow spittlebug, Philaenus spumarius (Homoptera), was investigated on islands in the Gulf of Finland. Long-term (30-year) investigations showed that the populations can survive through very narrow bottlenecks, but after strong reduction in the size of a population, random genetic drift may remove alleles or change allele frequencies. One of the factors sustaining the presence of almost all the colour polymorphism alleles in almost all the populations is gene flow. Migration seems to be largely by air and by the sea surface (anemohydrochoric). On one rocky island, gene flow was able to carry the top dominant allele,pT , to a number of scattered plant stands. However, it was not powerful enough to alter the differences in allele frequencies between populations living on the same island in meadows of different types 3 m or 12 m from each other. It is highly probable that the factor operating is meadow-specific selection. Its action appears to be based on the ecological character of the meadow. In the different meadows, the coverages of the food plants of the spittlebug are dissimilar. Differences in plant assemblages are possibly of importance in maintaining the meadow-specific allele frequencies in the spittlebug populations.

Selection often overrides the effects of random processes in island populations of Philaenus spumarius (Homoptera)

Abstract The influence of various evolutionary factors on the populations of the colour polymorphic meadow spittlebug, Philaenus spumarius (Homoptera), was investigated on islands in the Gulf of Finland. Long-term (30-year) investigations showed that the populations can survive through very narrow bottlenecks, but after strong reduction in the size of a population, random genetic drift may remove alleles or change allele frequencies. One of the factors sustaining the presence of almost all the colour polymorphism alleles in almost all the populations is gene flow. Migration seems to be largely by air and by the sea surface (anemohydrochoric). On one rocky island, gene flow was able to carry the top dominant allele, p T , to a number of scattered plant stands. However, it was not powerful enough to alter the differences in allele frequencies between populations living on the same island in meadows of different types 3 m or 12 m from each other. It is highly probable that the factor operating is meadow-specific selection. Its action appears to be based on the ecological character of the meadow. In the different meadows, the coverages of the food plants of the spittlebug are dissimilar. Differences in plant assemblages are possibly of importance in maintaining the meadow-specific allele frequencies in the spittlebug populations.

Oregon's Advance Directive for Mental Health Treatment: Implications for Policy

The poet narrates that Ulysses was forewarned about seductive sirens whose bewitching song lured sailors to their rocky island, near Scylla and Charibdis. These fabulous creatures promised seafarers knowledge, but brought about their death, Ulysses ordered his crew to fill their ears with wax. But he, desiring to hear the enchanted song, bade his sailors bind him to the mast. His heart throbbed with desire,

Microdistribution and fluctuations in niche overlap in a rocky shore cichlid community in Lake Victoria

Abstract— The microdistribution of ten numerically dominant species in a fish community at a rocky island in Lake Victoria was studied using invasive sampling. All were haplochromine cichlids. The community was characterized by high fish densities and by a dominance of Aufwuchs feeders. Species were non‐randomly distributed, showing significant associations with water depth and other topographic parameters. Species occupied unique positions in a network of recurrent species groups. Niche partitioning through differential microdistribution was even more subtle than that reported for Lake Malawi's rock‐dwelling cichlids. Species‐specific microdistribution fitted qualitative predictions from ideal free distribution models with asymmetrical interference competition for food. No evidence was found for interspecific contest competition for space. Temporal niche shifts have been observed between periods of high and low water levels. Owing to a combination of reduced habitat availability with niche expansion in most species, niche overlap was larger during the lowwater period.

Larvae of uncommon caridean decapods in the German Bight: Species composition, distribution and abundance

Typically, the most abundant group of shrimp larvae in the German Bight is formed by representatives of the family Crangonidae. Larvae of the remaining species have been largely ignored, and only scarce information concerning their ecology is available. Thus, the purpose of the present study was to determine the species composition, distribution and abundance of noncrangonid shrimp larvae in the German Bight in July 1990, after the mildest winter of the century. The material is based upon plankton samples collected at 77 stations, covering the entire German Bight. Eight species were identified, as well as larvae of Palaemonidae andProcessa-juveniles.Processa nouveli holthuisi (53.0%) andP. modica (31.3%) were predominant in the collection. The distribution of the two species was clearly separated: the main concentration ofP. nouveli holthuisi (peak concentration of 1.94 larvae per m3) was confined to the northwest corner of the German Bight, while a majority ofP. modica larvae (peak concentration of 0.54 larvae per m3) occurred at the southwesterly stations. The spatial distribution ofCaridion steveni andEualus occultus around Helgoland indicates the presence of an adult population at the only rocky island in the study area. Other taxa, such as larvae of Palaemonidae and juvenilePandalina brevirostris were collected exclusively in estuarine habitats. Based upon both the results of the present study and comparable data, we conclude that developmental stages of ten non-crangonid species, as well as representatives of Palaemonidae, can be expected to occur in the plankton of the German Bight. The extremely mild temperatures of the preceding winter may have been, in part, responsible for the relatively high densities of some taxa encountered during our plankton survey. We assume that warm winter temperatures favour the immigration, reproduction and survival of cold-sensitive species.

Dichotomous Facies on a Late Cretaceous Rocky Island as Related to Wind and Wave Patterns (Baja California, Mexico)

Local facies forming the basal Rosario Formation of the Upper Cretaceous in the Erendira area of northern Baja California (Mexico) were deposited in distinctive windward and leeward settings. They are related by a nonconformity to the flanks of an andesite ridge of the Lower Cretaceous Alisitos Formation. Through rapid transgression and erosion in late Cretaceous time, the ridge was reduced to a maximum width of a half-kilometer and its neck was breached by Rosario sediments to form a small near-shore island. One end of the Alisitos outlier is now being truncated by marine erosion so that the original length of the peninsula-island is difficult to determine. It was not less than 1.5 km long, however, based on local geomorphology

Fishing Arctic Foxes Alopex lagopus on a rocky island in West Greenland

On a small barren island in Disko Bay, west Greenland, 195 hours were spent observing Arctic foxes at their den and the nearby coast. Their main food was found to be live, caught fish, and the activity of the foxes was correlated with the tidal height. S. M. Nielsen, Arctic Station, University of Copenhagen. DK-3953 Godhavn, Greenland.

Fishing Arctic foxes Alopex lagopus on a rocky island in west Greenland

Fishing Arctic foxes <i>Alopex lagopus</i> on a rocky island in west Greenland

1997 and After: Will Hong Kong Survive? A Personal View

HONG KONG is, and always has been, a curiosity. It was born as a consequence of the activities of early nineteenth-century capitalists plying a trade of dubious morality along the south China coast. China's last imperial dynasty was simply unable to resist the incursion of British naval power support of its merchant adventurers. The Qing government was obliged to sign away (in perpetuity!) its right to administer a rocky island off the Guangdong coast. It gave the British an opportunity not merely to develop their own alternative to Portuguese Macau as a trading station for Western commerce China, but also allowed them fundamentally to challenge the very rules of the China trade by which Britain, and later other Western nations, could pressure a weak dynasty to act the interests of Western commerce. The centuries-old tributary system, already weak, virtually collapsed. China was obliged to confront Western commerce on Western terms, and, after the signing of a set of unequal treaties, that confrontation occurred on Chinese soil. China's door was forcibly opened-kicked in might be a better term-to the full force of an economic system that it was ill-prepared to meet.' The first British venture at colonialism the Far East was not met with enthusiasm. Even Palmerston, the arch-defender of British interests abroad, was uncertain about the value of the settlement which Elliot had wrested from the Chinese after the first Opium War. If Britain was to open China's doors by force-and Palmerston was not convinced that

Continuous underwater light measurement near Helgoland (North Sea) and its significance for characteristic light limits in the sublittoral region

Underwater irradiance was measured at intervals of 20 min for one year at 2 water depths (2.5 and 3.5 m below M.L.W.S.) and in 3 spectral regions in the sublittoral region of the rocky island of Helgoland. Data are presented for spectral and total irradiance at water depths ranging from 2 to 15 m (below M.L.W.S.). 90% of the total annual light reaching sublittoral habitats is received during the period from April to September, when Jerlov water type 7 (occasionally water type 5) dominates. During the other half of the year, the water is very turbid, and transparency is so low that long dark periods occur even at moderate water depths. The total annual light received at the lower kelp limit (Laminaria hyperborea), at 8 m water depth, is 15 MJ m−2 year−1 or 70 E m−2 year−1, which corresponds to 0.7% of surface irradiance (visible). At the lower algal limit (15 m water depth) these values are 1 MJ m−2 year−1 or 6 E m−2 year−1, corresponding to 0.05% of surface irradiance. These data are similar to measurements at the same limits in several different geographical areas, and may determine the depth at which these limits occur.

The scleractinian coral Archohella living on the coastal shores of Queensland, Australia

SUMMARY Live colonies of the oculinid genus Archohelia Vaughan, previously known only from the fossil records of the West Indies and Central and North America, have been discovered in shallow water off Rat Island on the coast of Central Queensland, Australia. Archohelia rediviva n. sp. differs from the genotypeA. fimonensis in having the tertiary septa regularly fused to the six secondary septa. The small white colonies of A. rediviva with branches up to 10 cm long grow more or less erectly from thin encrusting bases. They occur in 3.5 metres of sheltered, turbid water by the shoreline of a rocky island having no fringing coral reef. The coral is subject to strong tidal currents and large changes in salinity. There are no hints as to the provenance of this coral from the other occurrences of this genus or Oculina in Australia.

Meeresalgen von Helgoland

This report represents a photographic documentation of the more conspicuous species of the marine algal vegetation of the island Helgoland (North Sea), based on collections and observations made since 1959. The catalogue is largely restricted to macroscopic forms, as adequate knowledge of most of the microscopic ones is not yet available. Remarks on some rare species are added in a special chapter; the list includes some 150 species. With a few exceptions, the figures have been obtained from living algae; they illustrate aspects of reproduction and development and, occasionally, demonstrate different seasonal habits. The simplified key may be useful for providing a guide both for naturalists and students of marine phycology. In addition, this algal flora enhances our knowledge of the distribution of benthic species along the European coasts, as the rocky island of Helgoland intervenes between southern Norway and the shores of the English Channel.

A digital wind gust recorder

The instrument was a byproduct of an undergraduate final year project on wind power which was carried out by the Department of Mechanical Engineering of the University of Liverpool. The windmill test site was on an exposed, rocky island where there was no history of weather recording but a long tradition of violent winds. Field experience during the winter months suggested that corrosion fatigue arising from wind buffeting and salt spray would rank equally with maximum wind pressure as criteria of failure and if modern materials, so convenient for forming aerodynamic surfaces, were to be used then limited life concepts would need to be considered. This called for more knowledge of wind variations at the test site. A complete wind spectrum taken on chart recording instruments would have been ideal but since such such refined devices were not available the instrument to be described was designed. The only wind measuring instrument which was available was a rotating cup anemometer. This supplied an alternating voltage proportional to its rotational speed. It also operated a gear driven microswitch which could give an integrated “miles of wind” reading on an electromagnetic counter. Briefly the e.m.f. generated by the anemometer (Fig. 1) was matched against a pre-set voltage corresponding to the required gust velocity. When this was exceeded an appropriate counter was operated. Only the rising e.m.f. was significant. The subsequent fall was ignored. Initially three stages were incorporated which reported the gusts rising through forty, fifty and sixty knots, respectively. These recorded on separate counters. All basic settings were based on pitot-static speed determinations in a wind tunnel.

Asteris and the Twin Harbours

R. Lattimore's translation is neat and accurate:There is a rocky island there in the middle channel halfway between Ithaka and towering Samos,called Asteris, not large, but it has a double anchoragewhere ships can lie hidden. There the Achaeans waited in ambush.I assume that Homeric Ithaca is the island now called Ithaki and that Samos is Kephallinia. The channel will then be the Ithaca Channel, and here there is only one island, now called Daskalio (FIG. 1). So Daskalio = Asteris. So far, so good; Homer has deftly pinpointed the location of the ambush by associating it with the only small island off the west coast of Ithaca.Daskalio is certainly πετρήεσσα; indeed it is nothing but a narrow shelf of rock about 200 yards long, and rising only about 15 feet above water level (Plate IIIa). No one can deny that it is οὐ μεγάλη; the phrase may well be a litotes. It is not strictly in ‘mid-channel’, being 3,000 yards from Ithaca and only 800 yards from Kephallinia, but this may pass in a poetic description. It is with the ‘double anchorage’ that Homer's description appears to lose touch with reality.

The evolution of an atoll: the depositional and erosional history of Aldabra

The earliest sediments identified of late Pleistocene age are quiet-water calcarenites, containing abundant molluscs but few corals. As waters shallowed these were replaced by emergent intertidal sediments, probably colonized by mangroves. Further emersion into subaerial conditions resulted in cementation and solution of the limestones to form a dissected karst topography. Perhaps concurrent with this, phosphates, probably originally derived from sea birds, were deposited in open cavities. Further marine withdrawal caused the erosion and re-deposition of these phosphatic sediments at a lower level. A succeeding event was the formation of a sand cay at the western end of the atoll. Its emergent surface was colonized by tortoises, birds, crocodiles and snails, and the youngest deposits indicate the presence of at least seasonal bodies of standing fresh water. This terrestrial interlude was followed by inundation by a sea, perhaps 2-3 m higher than the present level, in which was deposited a fairly uniform limestone over the whole area of proto-Aldabra. The limestone consists largely of calcareous algae set in a calcilutite-calcarenite matrix, in which both corals and molluscs are low in numbers and diversity. The emergence that followed caused widespread erosion and the island formed, surrounded by low cliffs, was subject to solution fretting and a limited deposition of soils. Renewed submergence carved proto-Aldabra into a broad shallow bank, with an almost flat ring-like rim around the periphery, while re-emergence allowed deposition on this bank of a series of sandbanks, beaches and terrestrial soils. These deposits were truncated by a marine erosion surface which marked the beginning of a sea-level rise that continued to a level at least 8 m above present datum, proto-Aldabra (125000 years b.p.) then consisting of a shallow bank covered by coral-rich calcarenite. Coral growth was more prolific around the rim, but coral knolls were also common within the rim to the northwest, where both coral and mollusc diversities are highest. The dominant sediment in the southeast is a Halimeda -rich sand with relatively little coral growth, but the presence of abundant Acropora around the southeast rim suggests that the dominant wind was from this quarter. Early in the deposition of this rock unit a sea-level oscillation resulted in temporary emergence, causing a change in facies or a break in deposition. A subsequent drop in sea level resulted in the cutting of a terrace at about 8 m and a more conspicuous terrace at around 4 m. Aldabra then stood as a ring of narrow, low, rocky islets surrounding a broad shallow lagoon. Deposits with a land-fauna including crocodiles, tortoises and lizards possibly date from this period. Continued depression of the sea level as a result of the Wurm/Wisconsin glaciation left Aldabra as a steep-sided rocky island, perhaps up to 100 m high. This was well vegetated, and a high rainfall caused much solutional erosion. Sea level, in response to post-Glacial climatic warming, has risen to its present position, a principal consequence being the breaching of the land rim and the flooding of the lagoon to reduce the land area by almost 60 %. Small cavity-fill deposits, caves, and stromatolitic coatings have been formed since the last interglacial, but it is difficult to place them in sequence. A restless history, of changes in the size, shape and character of Aldabra had important effects upon both the marine and terrestrial biotas. The giant tortoise, Testudo gigantea , was eliminated and has recolonized the area on at least two occasions; and the faunas and floras characterizing the sediments of each marine event are very different in composition. The evidence presented does not accord with the popular view of reef growth as steady accretion. The limestones were formed as discrete increments, often with dramatic facies changes between one unit and the next.

Standing crop and leaf area index of the sublittoral Laminaria species near Helgoland

Standing crop values of Laminaria species sampled between 0 to 2 m depth in the sublittoral of Helgoland, a small rocky island in the southern North Sea, are similar to those reported by other workers from Norwegian or Scottish coasts. Below 2 m water depth, however, standing crop values are found to be reduced to a far greater extent with increasing depth than in the Norwegian or Scottish areas studied. Maximum standing crop values are not found in Laminaria digitata and L. saccharina growing just below the low water mark of spring tides, but in the upper L. hyperborea forest at 2 m depth. Population density and leaf area index (LAI) decrease with increasing depth (but not the average weight of individuals constituting the L. hyperborea forest). It is suggested that the depth at which LAI becomes 1 represents an important ecological threshold, since growth rates of L. hyperborea specimens appear to decrease at greater depths but not to increase above the threshold. Self-shading might equalize, to a certain extent, the quantity of underwater irradiance available to an individual phylloid at all depths at which a close vegetation of Laminaria species occurs.

Growth of amputated and dark-exposed individuals of the brown alga Laminaria hyperborea

The seasonal growth of the brown alga Laminaria hyperborea (Gunn.) Foslie, which forms dense forests in the sublittoral zone of Helgoland, a rocky island in the Southern North Sea, was investigated by transplanting specimens of medium size onto PVC or wooden plates fixed to sub-tidal grwoth stations. The 2-year study revealed that, during the season of fast growth (January to June), young plants produce each year a new frond, larger in size than in the preceding year. This observation can be interpreted, in part, by assuming that the growth of the young frond is accomplished not only by its own assimilatory surplus, but also by reserve materials of the old frond assimilated during the preceding season of slow growth. This assumption is supported by experimental evidence: (1) Even in complete darkness Laminaria hyperborea is capable of producing a small new frond during the season of fast growth; (2) New fronds with stipe, but without old frond, grow (during the same period) considerably faster than isolated new fronds separated from the possible sources of reserve materials. Maximum growth occurs in normal plants which possess their old frond until April or May.

A bird survey of Iriomote I., Yaeyama Group, S. Ryu Kyus

1. As an expedition member of Yokkaichi Minami High School to the Yaeyama Group, S. Ryu Kyus, the author investigated birds on Iriomote I. and the adjacent Nakano-Kamijima.2. Thirty eight species of 23 Families including 7 species new to the islands, were recorded of which 32 species were common to Japan and 37 to Formosa. Nineteen species were common to Japan and 21 to Formosa as subspecies.3. The islands are of special interest as an intergrading area between oriental and palearctic zones and among observed species, the following were interesting zoogeographically and ecologically: Passer montanus (new record), Lanius cristatue lucionensis (on migration), Hirundo tahitica, Sula dactylatra, Thalasseus bergii, Streptopelia orientalis stimpsoni and Sterna sumatrana. The latter two species breed on a small rocky island and Streptopelia were breeding colonially in high density at a grassy place (not on the) and flew over the sea to the feeding place on the oposite coast.4. On Nakano-Kamijima, there was a mixed sea-bird colony consisting of Anous stolidus, sterna fuscata, Calonectris leucomelas (possibly the southern limit), and Sula leucogaster, with the total of some 20, 000 individuals. There habitat segregation especially between Sterna and Anous was demarcated.5. On this island sea-bird eggs are being taken in great numbers and the protection from this is considered to be urgently needed.

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