Evidence from the Lake Champlain Valley for a later onset of the Champlain Sea and implications for late glacial meltwater routing to the North Atlantic

Ocean circulation models indicate that freshwater runoff from the North American continent during the last deglaciation may have had an effect on North Atlantic Ocean circulation, and thereby have altered regional climate. One such example is a flood from Lake Agassiz, which has been proposed by previous workers to have caused the onset of the Younger Dryas at around 12,850 calibrated years B.P. by entering the North Atlantic through the Gulf of St. Lawrence. We present two radiocarbon ages from terrestrial organic sources in the Champlain Valley that we associate with the pre-Champlain Sea proglacial lake phases; a musk-ox bone with an AMS age of 11,362 ± 115 ¹⁴C years B.P. (13,438-13,020 calibrated years B.P.), and a wood fragment with an AMS age of 10,901 ± 76 ¹⁴C years B.P. (12,995-12,793 calibrated years B.P.). These ages together with a glacial lacustrine varve estimate suggest that the initiation of the Champlain Sea may not have occurred until after the onset of the Younger Dryas. If the Lake Agassiz flood event occurred before the opening of the Champlain Sea then the floodwaters would have been diverted down the Champlain and Hudson valleys to the North Atlantic. Another possibility is that the Agassiz flood may have been contemporaneous with the opening of the Gulf of St. Lawrence. It is also possible that there may have been a large enough flood produced by meltwater originating in the Champlain Valley and St. Lawrence Lowlands at the inception of the Champlain Sea to have affected ocean circulation without the influence of Lake Agassiz.     

An Insight into Paleovegetation on the Emerged Shelf at the Last Glaciation: Pollen Date of the South China Sea

Vegetation on the emerged continental shelves of the South China Sea (SCS) during the Last Glacial Maximum (LGM) was deduced based on pollen of hemipelagic sediments from the continental slopes and the consideration of pollen transport dynamics and source areas. During the LGM (including the top of Oxygen Isotope Stage 3) the sea level might be more than 100 m lower than that of the present. Consequently, both northern and southern continental shelves of the SCS were exposed. The northern continental shelf was covered by grassland mainly of Artem/s/a. The climate should be cold and dry, whereas on the southern continental shelf (Sunda Land) was spread tropical lowland rainforest and mangroves were scattered by the river mouths and along the coast. The climate might be cooler than that in the present day, but drop of humidity was not observed.     

Distribution and dynamics of two species of Dinophyceae producing high biomass blooms over the French Atlantic Shelf

The frequency and distribution of high biomass blooms produced by two dinoflagellate species were analysed along the French continental shelf from 1998 to 2012. Two species were specifically studied: Karenia mikimotoi and Lepidodinium chlorophorum. Based on remote-sensing reflectances at six channels (410, 430, 480, 530, 550 and 670 nm), satellite indices were created to discriminate the species forming the blooms. A comparison with observations showed that the identification was good for both species in spite of a lower specificity for L. chlorophorum. The overall analysis of the satellite indices, in association with some monitoring data and cruise observations, highlights the regularity of these events and their extent on the continental shelf. L. chlorophorum blooms may occur all along the South Coast of Brittany. All the coastal areas under the influence of river plumes and the stratified northern shelf area of the Western English Channel appear to be areas of bloom events for both species. These two species are likely to be in competitive exclusion as they share the same spatial distribution and the timing of their bloom is very close. Finally, due to the scarcity of off-shore observations, these satellite indices provide useful information regarding HABs management and the development of a warning system along the French coast.     

Evaluation of Scientific Evidence by International Courts and Tribunals in the Continental Shelf Delimitation Cases

Evaluation of scientific evidence is one of the challenges arising in the tribunal and court cases that deal with the continental shelf beyond 200 nautical miles (nm). Given the difficulties rooted in the interface between law and science regarding the establishment of the entitlement to the continental shelf beyond 200 nm, the current judicial practice offers limited guidance in enhancing transparency and openness in evaluating the scientific evidence. Utilizing procedures providing for the assistance of experts is advisable, as this could facilitate the achievement of an equitable solution in the cases.     

Late Quaternary stratigraphy and sedimentology of Orphan Basin: Implications for meltwater dispersal in the southern Labrador Sea

Orphan Basin is a deep-water basin on the continental margin off Newfoundland, which throughout the late Quaternary received proglacial sediment from local ice that crossed the continental shelf. Sediment from more distant sources was transported southward in the Labrador Current as proglacial plumes and in icebergs. Five sedimentary facies related to glacial processes are distinguished in cores recovered from Orphan Basin: hemipelagic sediment, nepheloid-layer deposits (layered mud), beds rich in ice-rafted detritus (IRD), sand and mud turbidites, and glaciogenic debris-flow deposits. IRD-rich beds correspond to periods of intensified iceberg calving, and layered mud, turbidites, and glaciogenic debris-flow deposits with glacial meltwater discharge.

In the Late Wisconsinan, eight periods of meltwater discharge and iceberg calving from the Newfoundland ice sheet are interpreted from the sediment facies in Orphan Basin. These discharges coincide with the terminations of the colder periods of the D–O cycles recorded in Greenland ice cores. The oldest minor meltwater event (27.5–28.5 cal ka) corresponds to the first Late Wisconsinan ice advance across the Grand Banks and NE Newfoundland Shelf. The following three meltwater discharges (23–23.5, 23.8–24.5, and 25–27 cal ka) deposited sand turbidites and glaciogenic debris-flow deposits seaward of Trinity Trough, which was occupied by an ice stream at this time, and mud turbidites in the southern part of the basin derived from a mid-shelf ice margin on the Grand Banks. Four periods of meltwater discharge occurred during the deglaciation and are centered at 15, 18.5, 19.75, and 20.75 cal ka. The youngest is correlated to Heinrich event 1. In the literature, the 18.5 and 20.75 cal ka events have been recorded in multiple glacial settings in the North Atlantic, and therefore, are interpreted as large-scale events of meltwater discharge and iceberg calving, but in Orphan Basin the 19.75 cal ka event is also of similar scale.     

Third Party Intervention in the Commission on the Limits of the Continental Shelf Regarding a Submission Involving a Dispute

The Commission on the Limits of the Continental Shelf (CLCS) was established in accordance with Article 76 of the Law of the Sea Convention. CLCS has the mandate to consider data submitted by coastal states concerning the outer limits of their continental shelf in areas where those limits extend beyond 200 nautical miles and to make recommendations to the submitting state on matters related to the establishment of the limits. For third parties that have actual or potential disputes, unresolved borders, or unresolved land or maritime disputes with the submitting state, the recommendations of the CLCS can be very sensitive. The focus of this article is on the practice of third parties in responding to submissions and how third parties have constructed their Notifications.     

Geochemical processes affecting meltwater chemistry and the formation of saline ponds in the Victoria Valley and Bull Pass region,Antarctica

Major ion, trace element and nutrient concentrations have been determined in meltwater streams, frozen lakes and isolated saline ponds of the Victoria Valley and Bull Pass regions in Victoria Land, Antarctica. Geochemical processes affecting glacial meltwater composition with time and distance from the source glaciers include solute acquisition by soil salt leaching and solute concentrations by evaporation. Evaporation in the marginal lake melt and in isolated saline ponds appears to increase the Mg/Ca ratio of these meltwaters relative to that of meltwater streams. With progressive evaporation gypsum and calcite may precipitate, leading to the development of Na-Cl and Na-HCO₃ brine ponds. These ponds may be vertically stratified with respect to temperature and salinity if they experience partial or complete freezing over the winter season. The chemical characteristics and nutrient concentrations of meltwaters in the Victoria Valley are similar to those of other drainage systems in the region, although the Ca-Cl brines reported from the Wright Valley immediately to the south were not observed. Trace element (Cu, Pb, Zn, Cd, Mn and Fe) concentrations measured in the lakes and large ponds do not show any evidence of unusual enrichment in the drainage.     

Coastal States in the South China Sea and Submissions on the Outer Limits of the Continental Shelf

The purpose of this article is to examine the outer continental shelf submissions made by the coastal states of the South China Sea and their potential impact on legal and political developments in the South China Sea. In accordance with the United Nations Convention on the Law of the Sea of 1982 and the guidelines of the Commission on the Limits of the Continental Shelf, coastal states are to establish the outer limits of their continental shelf where it extends beyond 200 nautical miles. Meeting this obligation is complicated in enclosed or semienclosed seas where there are maritime disputes such as in the South China Sea.     

Investigation of the Shelf Ecological System on the Basis of Modeling and Field Work

Mathematical modelling of the ecosystem of the North-West shelf of the Black Sea is based on the method of aggregation and averaging with the subsequent hierarchic decomposition (BELYAEV , 1987; BELYAEV and KONDUFOROVA , 1989). This approach includes the step-by-step comparison of the modelling results with field observations. The observations have been performed during the integrated oceanographic expedition of the research vessel “Professor Kolesnikov” (1987), for the first time specially organized to verify the modelling results. The comparison of the results of modelling and observation demonstrated that their agreement is satisfactory quantitatively and qualitatively. The efficiency of using models of optical fields for verification is also shown.     

The Outer Continental Shelf of Coastal States and the Common Heritage of Mankind

The establishment of the outer limits of the continental shelf not only involves the rights and interests of coastal states, but also the interests of the international community as a whole. This article examines this balance between coastal states’ assertions of their outer continental shelf limits and the common heritage of mankind.     

The Delimitation Method for the Continental Shelf Beyond 200 Nautical Miles: A Reflection on the Judicial and Arbitral Decisions

Abstract

This article examines the practice of the international judicial and arbitral tribunals thus far in delimiting the continental shelf beyond 200?nm, and indicates the trend reflected in the decisions. However, the article disagrees with the critical observation of the tribunals that the delimitation method for the continental shelf beyond 200?nm should follow that within 200?nm. The delimitation of the continental shelf beyond 200?nm is essentially different from the single maritime delimitation within 200?nm, and various methods may be employed in order to achieve an equitable result in a particular case.     

Comparison of Community Structure of Soft-Bottom Macrobenthos of the Newport Submarine Canyon,California and the Adjoining Shelf

Community structure of soft-bottom macrobenthos from Newport Submarine Canyon, California, was compared to that on the adjoining shelf. Four hypotheses involving sediment characteristics, community structure, benthic feeding types and seasonal population fluctuations were posed. Results indicated that there were statistically significant differences between the canyon and adjoining shelf. Although there were differences in sediment geochemistry between the canyon and shelf, sediment type played the major role influencing differences in community structure and feeding. Operation of a shelf outfall has not demonstrably changed the canyon soft-bottom macrobenthos for at least 16 years and probably closer to 27 years.     

Associations and distribution of benthic nematodes in the Ethiopian Rift Valley lakes

The nematode associations in six Ethiopian rift lakes, one man-made lake, and three crater lakes were studied and related to water conductivity, lake depth and sediment particle size. The lakes investigated lie at moderate altitudes (1200–2000 m), are alkaline and vary in their conductivities. The rift lakes Abijata and Shala and the crater lakes Aranguadi, Kilotes and Chitu are soda lakes (K₂₅ > 6000 μS cm⁻¹), while the remaining five lakes and the man-made Lake Koka are within the freshwater range of conductivity (K₂₅ < 6000 μS cm⁻¹). A total of 16 species were identified including six new species. The nematode associations varied between lakes and were restricted to very few species in each lake. Most nematodes were restricted to non-saline lakes. The most dilute L. Zwai had a higher number of nematode species (12) and abundance than other lakes. The saline lakes Shala and Kilotes had nematode assemblages made up of only a single species (Mesodorylaimus macrospiculum). No nematodes were found in the hypersaline crater L. Chitu. Tobrilus africanus appeared more euryhaline than other nematodes occurring at conductivities as high as 15 000 μ S cm⁻¹ (L. Abijata). Five of the most common species (Dorylaimus sp., Monhystera stagnalis, Aphanolaimus tudoranceai, Tobrilus africanus and Actinolaimus perplexus) were associated with medium grained sand. A monthly variation in density of nematodes in L. Zwai is also shown.     

On the Vertical Distribution of the Metazoan Meiofauna in Shelf Break and Upper Slope Habitats of the NE Atlantic

The metazoan meiofauna of nine stations in shelf break and upper slope areas (70 to 1500 m water depth) of the N.E. Atlantic were investigated in order to assess which environmental factors are important in the control of densities and sediment profiles. Total meiofaunal densities (ranging between 368 and 1523 ind/10 cm²) were correlated with bacterial densities, an important food source for meiofauna. However, considering sediment vertical distribution profiles, the relative importance of both food and oxygen on the meiofauna became obvious. A combination of both bacterial densities and oxygen supply could explain about 95% of the variability in the vertical profiles of the meiofauna densities. Meiofauna numbers increase in proportion to food availability in the surface sediment layers, but this relationship breaks down in deeper sediment layers where the oxygen supply is often limiting, particularly in fine sediments.     

Mixotrophic cryptophytes and their predators in the Dry Valley lakes of Antarctica

1. The ingestion rates of planktonic, mixotrophic cryptophytes in two perennially ice-covered Antarctic lakes in the McMurdo Dry Valleys, were investigated during the summer of 1997–1998.
2. In Lake Fryxell, which is meromictic, ingestion rates increased with depth in November and were highest in a cryptophyte maximum close to the chemocline. In Lake Hoare, which is unstratified and freshwater, there was no significant difference in ingestion rates with depth. In both lakes, the highest ingestion rates occurred in early summer, decreasing in December and January. Ingestion rates varied between 0.2 bacteria cell⁻¹ h⁻¹ and 3.6 bacteria cell⁻¹ h⁻¹.
3. During November, mixotrophic cryptophytes removed up to 13% of bacterial biomass day⁻¹ and had a greater grazing impact than heterotrophic nanoflagellates (HNAN). As summer progressed, the grazing impact of cryptophytes and HNAN became similar.
4. The maximum depth of cryptophytes in Lake Fryxell was predated by a population of the ciliate Plagiocampa. Plagiocampa had an ingestion rate of 0.13–0.19 cryptophytes cell⁻¹ h⁻¹. The grazing impact on the cryptophyte community was insignificant. However, the ciliate appeared to be indulging in temporary mixotrophy, sequestering the cryptophytes for a number of weeks before digesting them.
5. It is suggested that mixotrophy is an important survival strategy in the extreme lake ecosystems of the McMurdo Dry Valleys.     

Managing Adjacency: Some Legal Aspects of the Relationship Between the Extended Continental Shelf and the International Seabed Area

The Third United Nations Conference on the Law of the Sea (1973–1982) struck a difficult compromise between the definition of the outer limits of the extended continental shelf (ECS) in relation to the international seabed area (the Area) and the making of payments and contributions by the coastal state in relation to production activities on its ECS in Article 82. The implementation of Article 82 underscores a broader and more far-reaching relationship between the continental shelf, and the ECS in particular, and the Area. In some regions there may be a relationship between the exclusive economic zone and the Area, where there is no ECS. Effectively, the relationship translates into realities and expectations of good neighborliness. This article examines this relationship and the possible approaches for the management of identified challenges.     

Drivers of parasite community structure in fishes of the continental shelf of the Western Mediterranean: the importance of host phylogeny and autecological traits

We explored the relationships between features of host species and their environment, and the diversity, composition and structure of parasite faunas and communities using a large taxonomically consistent dataset of host-parasite associations and host-prey associations, and original environmental and host trait data (diet, trophic level, population density and habitat depth vagility) for the most abundant demersal fish species off the Catalonian coast of the Western Mediterranean. Altogether 98 species/taxa belonging to seven major parasite groups were recovered in 683 fish belonging to 10 species from seven families and four orders. Our analyses revealed that (i) the parasite fauna of the region is rich and dominated by digeneans; (ii) the host parasite faunas and communities exhibited wide variations in richness, abundance and similarity due to a strong phylogenetic component; (iii) the levels of host sharing were low and involved host generalists and larval parasites; (iv) the multivariate similarity pattern of prey samples showed significant associations with hosts and host trophic guilds; (v) prey compositional similarity was not associated with the similarity of trophically transmitted parasite assemblages; and (vi) phylogeny and fish autecological traits were the best predictors of parasite community metrics in the host-parasite system studied.