Open Coastal Areas Research Articles

An Irregular Wave Propagation Model Application to an Open Coastal Area

Abstract In this paper the DREAMS_CR_S model for propagation and deformation of random waves (characterized by a directional spectrum) over regions of variable depth is described. It is based on the linear superposition of the wave fields obtained from a monochromatic wave model for several frequency–direction components in which the incident directional spectrum is discretized. The model predicts the effects of refraction, diffraction, shoaling, reflection, and wave breaking. The model was applied to a real case—the Ancao Inlet at Ria Formosa, in Algarve (Portugal). Incident wave model conditions were chosen from measurements by a directional buoy, deployed over the seabed at −25 m depth below chart datum. The results illustrate that the model without breaking is working well and can be applied to areas with complex bathymetry. When breaking is taken into account, the results are not very accurate. The wave-breaking iterative process and the estimation of the breaking point used in the model have to be i...

Biogeochemical processes in the ocean and at the ocean-atmosphere interface

The ocean can be considered as a chemical reactor, whose energy sources are the various matter inputs originating from the continent and the ocean. Among various elements, carbon plays a key role as it is involved in both inorganic form as CO 2 and organic forms such as compounds synthesized through photosynthesis. Thus, the ocean is presently an active actor in climate change and ocean-atmosphere exchange processes. This review will present some insights into: 1) schematic representations of the carbon cycle, with emphasis on CO 2 exchange between the ocean and the atmosphere and to the organic parts of this cycle, 2) concepts relative to the biological pump of CO 2 , with a detailed view on photosynthesis, 3) concepts leading to the existence of oceanic provinces and associated productivity for open sea and coastal areas, 4) addressing the question: what is the net efficiency of the biological pump of CO 2 in terms of exportation of organic carbon and sequestration in sediments and 5) specific aspects on biogeochemical processes occurring at the boundary between the ocean and the atmosphere.

A new general dynamic model predicting radionuclide concentrations and fluxes in coastal areas from readily accessible driving variables

This paper presents a general, process-based dynamic model for coastal areas for radionuclides (metals, organics and nutrients) from both single pulse fallout and continuous deposition. The model gives radionuclide concentrations in water (total, dissolved and particulate phases and concentrations in sediments and fish) for entire defined coastal areas. The model gives monthly variations. It accounts for inflow from tributaries, direct fallout to the coastal area, internal fluxes (sedimentation, resuspension, diffusion, burial, mixing and biouptake and retention in fish) and fluxes to and from the sea outside the defined coastal area and/or adjacent coastal areas. The fluxes of water and substances between the sea and the coastal area are differentiated into three categories of coast types: (i) areas where the water exchange is regulated by tidal effects; (ii) open coastal areas where the water exchange is regulated by coastal currents; and (iii) semi-enclosed archipelago coasts. The coastal model gives the fluxes to and from the following four abiotic compartments: surface water, deep water, ET areas (i.e., areas where fine sediment erosion and transport processes dominate the bottom dynamic conditions and resuspension appears) and A-areas (i.e., areas of continuous fine sediment accumulation). Criteria to define the boundaries for the given coastal area towards the sea, and to define whether a coastal area is open or closed are given in operational terms. The model is simple to apply since all driving variables may be readily accessed from maps and standard monitoring programs. The driving variables are: latitude, catchment area, mean annual precipitation, fallout and month of fallout and parameters expressing coastal size and form as determined from, e.g., digitized bathymetric maps using a GIS program. Selected results: the predictions of radionuclide concentrations in water and fish largely depend on two factors, the concentration in the sea outside the given coastal area and/or adjacent coastal areas and the ecological half-life of the radionuclide in the sea. Uncertainties in these factors generally dominate all other uncertainties, e.g., concerning the surface water retention time, the settling velocity of the particulate fraction, the distribution coefficient regulating the fluxes in dissolved and particulate phases, the catchment area influences and the factors regulating biouptake and excretion of the radionuclide in fish. This means that the conditions in the sea are of paramount importance for the conditions in the coastal area, even for relatively enclosed coastal areas. This coastal model may be regarded as a tool for testing working hypotheses on the relative roles of different processes in different coastal areas. Such information is essential for getting realistic expectations of various remedial measures, such as coastal dredging discussed in this work.

離れ島状に形成されたアマモ場の消長と波浪環境

In open coastal sea area in which turbulence by ocean waves constitutes severe conditions for growth of eelgrass, eelgrass grows densely and maintains its own vegetation by stabilizing the sandy substrate. The larger the scale of vegetation, the more effective is this function, but on the other hand, in forming eelgrass beds, it is more effective to allow eelgrass to form in small patchy beds interspersed with bare areas as much as possible. In order to obtain the basic data for formulating this kind of efficient eelgrass bed formation plan, the authors are conducting field observation surveys. The target site is an extremely small-scale eelgrass bedformed like a remote island in the sea, and the prosperity and decay of the eelgrass bed has been observed and surveyed several times a year for the last three years and nearly every month in 2003. In addition, a wave environment that exerts a great influence over the prosperity and decay of eelgrass was observed at that spot.

The epibenthic megafaunal and benthic infaunal invertebrates of Port Foster, Deception Island (South Shetland Islands, Antarctica)

Abstract Otter trawl and grab samples (0.3 mm sieve) collected in Port Foster, Deception Island, from March 1999 to November 2000 as part of the ERUPT Antarctic ecosystem study were used to assess the status of the epibenthic megafaunal and benthic infaunal communities, which were heavily impacted by the volcanic eruptions of 1967–1970. Additional otter trawls were collected in coastal waters off Livingston and King George Islands to compare the epibenthic megafauna community of Port Foster with that of open coastal Antarctic environments. The epibenthic and infaunal communities of mid-bay Port Foster have significantly recovered since 1967 when mid-bay dredge and grab samples yielded a total of four individuals in two dredge hauls and an infaunal abundance of 40 individuals m −2 . Port Foster trawls from this study yielded an average of 26.2 taxa for the five sampling dates, with a cumulative total of 68 taxa. The epibenthic community at Port Foster was primarily composed of deposit feeding taxa with the ophiuroid, Ophionotus victoriae the dominant organism. Livingston and King George trawls yielded a total of 99 and 135 taxa, respectively, with a dominant suspension-feeding community of sponges and tunicates supporting a more diverse rich epibenthic fauna. Benthic infaunal abundance and biomass averaged 85,566.3 individuals m −2 and 121.951 g m −2 . Foraminifera, nematodes, and polychaetes were the most abundant infauna in Port Foster sediments representing 59.05%, 17.48% and 16.38% of total abundance, respectively. Bivalve mollusks and polychaetes were the major contributors to the biomass, with 48.375% and 45.294% of total wet weight, respectively. Abundant populations of microbiota (foraminiferans) and meiofauna (nematodes) suggest that, as in other benthic habitats, these small but numerous organisms play a key role in carbon utilization and the food web. Sediment type and food resources are major factors controlling the benthic community structures of Port Foster and Livingston and King George Islands. The accumulation of sediments in Port Foster from wind and melt-runoff associated with past volcanic activity limits the suspension feeding community and is a possible source of metals contamination. Warming of the Antarctic polar environment will likely increase sedimentation at Port Foster and open coastal areas as glaciers melt and land surfaces are exposed to wind and rain.

The influence of incubation periods on photosynthesis–irradiance curves

In phytoplankton primary production studies, samples for the determination of photosynthesis versus irradiance relationship ( P– I) are usually incubated at several irradiance levels during a fixed time period, commonly 2–4 h. However, it is not clear if the use of this fixed incubation time is appropriate to study the P– I relationship in any given ecosystem. The aim of this work was to study the influence of incubation time on the P– I relationship in natural phytoplankton populations from three different coastal ecosystems: an open coastal area, an estuary, and a coastal lagoon. Physical and chemical variables, phytoplankton biomass, species composition, and P– I curves were analysed. The results showed that, in the coastal area and in the estuary, P– I relationships were time dependent, whereas in the coastal lagoon different incubation periods produced the same P– I curve. An underestimation of daily primary production, ranging from 13% to 42.5%, was calculated when data from standard incubation times (2–4 h) were used in ecosystems where P– I curves present a dynamic time-dependent behaviour. This work suggests that the response of the P– I curves to the incubation time varies with the characteristics of the ecosystem and is related to the light regime to which phytoplankton cells are adapted.

Size‐dependent mortality of juvenile Atlantic cod, estimated from recaptures of released reared cod and tagged wild cod

The recapture rate and survival of reared cod Gadus morhua L. (15–45 cm) released in fjords and open coastal areas of Norway increased with increasing size at release, while release area and season also had a significant influence on the results. High mortality soon after release reduced the number of released fish by more than two–thirds within 6 months, and reduced the potential commercial yield to a low level. In most cases the recapture yield was lower than the released biomass and the net yield increased little or not at all with increasing size at release. In western Norway high fishing mortality of young fish reduced the numbers of surviving fish rapidly and the growth overfishing reduced the potential yield still further. Natural mortality decreased with increasing size at release, and became low when the fish approached their size refuge, i.e. when they could not be eaten by their usual predators.

Recent evolution in Baltic Fucus vesiculosus: reduced tolerance to emersion stresses compared to intertidal (North Sea) populations

The Baltic is a young, brackish and non-tidal sea, supporting an impoverished marine flora compared with adjacent open coastal areas. Populations of the normally intertidal brown alga Fucus vesiculosus L. are permanently submerged in the Baltic. We tested the hypothesis that these populations have evolved a reduced ability to withstand water-stresses caused by aerial exposure (desiccation and freezing), relative to adjacent intertidal populations in the North Sea. Desiccation and freezing tolerance were compared using chlorophyll fluorescence to monitor photosynthetic sta- tus during stress and recovery. To control for the influence of growth salinity on stress tolerance, the experimental material consisted of either adult algae cross-acclimated at Baltic and North Sea salin- ities (6.5 and 20 to 24 practical salinity units (psu), respectively), or juveniles from both populations grown in the Baltic from embryos (submersed, 6.5 psu). Baltic algae were less able to recover maxi- mum photochemical yield (Fv/Fm) after freezing at -15°C than North Sea algae, and neither acclima- tion (adults) or growth salinity (juveniles) accounted for between-population differences. During des- iccation at 5°C, differences in the response of variable fluorescence (Fv), as well as in initial fluorescence (F0) and Fv during recovery, indicated that impaired photoprotective processes may con- tribute to the inability of Baltic algae to fully recover Fv/Fm after stress, in contrast to North Sea algae which displayed dynamic and rapidly recoverable reductions of Fv/Fm. Subsequent desiccation experiments during the summer (at 25°C) showed that, relative to North Sea algae, the effective pho- tochemical yield (ΔF/Fm') of Baltic algae started to decline at lower tissue-water content (TWC) and recovered less completely after a return to seawater. A critical TWC of ca 10% for Baltic populations was identified, below which ΔF/Fm' did not fully recover. In addition, Baltic algae were less able to regain initial TWC during recovery. These results indicate that, in ca 7500 yr since the recruitment of the present marine flora to the Baltic, F. vesiculosus has evolved reduced tolerance to emersion stresses compared to adjacent intertidal populations.

A comparison of ship- and scatterometer-derived wind speed data in open ocean and coastal areas

Quality controlled wind speed observations from merchant ships have been compared with ERS-1 scatterometer data. The ship and satellite wind speed pairs were well correlated at 120 km separation in the open ocean, reducing to 40 km in the North Sea. The maximum allowed separation of ship and scatterometer wind speed pairs had to be further reduced to 20 km in the North Sea to avoid matching of coastal ship wind speed data with scatterometer data from more exposed regions. Spurious biases in the comparisons were caused by the error variability of the scatterometer data (0.5 m s-1) being significantly less than that for the ships (2.0 m s-1). The unbiased regression was: U10n(ship)=1.025 U10n(satellite)+0.255 No significant enhancement of the scatterometer wind speeds occurred in the coastal region.

Use of Habitat, Size of Prey, and Food-Niche Relationships of Two Sympatric Otters in Southernmost Chile

In Magallanes (southernmost Chile), the marine otter Lutra felina tends to use more open and wave-exposed coastal areas, whereas L. provocax is found in more protected habitats. To investigate the hypothesis that the two species segregate habitats to avoid competition for food, we surveyed the available literature on food habits and analyzed food-niche relationships of both species of otters in Magallanes. Overlap of diet between species of otters was relatively high, and L. provocax tended to have a narrower diet than L. felina . Both species consumed prey of similar size. These findings are consistent with the use of different habitats to avoid competition for food resources. However, alternate models, including habitat segregation resulting from differential abilities of the two species at catching prey in more wave-exposed habitats, deserve some attention. Our analysis also revealed that niche breadth and size of prey taken by L. felina at three sites along the Chilean coast were relatively similar. At Chiloe, however, L. felina exhibited the narrowest diet and consumed the largest prey. Although such a difference might be related to variation in abundance of prey among localities, it may also have resulted from the relatively small sample available for Chiloe.

China, modernisation and the goal of prosperity: government administration and economic policy in the late 1980s

Preface Introduction Ma Hong Part I. National Financial Management: 1. Government financial regulation 2. Monetary policy and monetary system 3. Bonds, stocks, banks and insurance 4. Price reform 5. Taxation policy Part II. Economic Law and Administration of Industry: 6. The economic legal system 7. Economic planning 8. Administration of industry and commerce 9. Enterprise classification and management 10. Employment, wages and welfare 11. Housing, land use and environmental protection Part III. Industrial Production and Infrastructure: 12. The structure of industry 13. Fixed asset construction 14. Industrial materials and equipment 15. The provision of energy, transport and communication services 16. The electronics, nuclear and astronautical industries Part IV. Rural Production: 17. Agricultural production 18. Township enterprise production Part V. Foreign Investment: 19. Foreign economic and technical cooperation 20. China's foreign investment experience 21. Open coastal areas and special economic zones Editor's Conclusion Index.

Intertidal Benthic Foraminiferal Biofacies on the Central Gulf Coast of Texas: Modern Distribution and Application to Sea Level Reconstruction

Intertidal Benthic Foraminiferal Biofacies on the Central Gulf Coast of Texas: Modern Distribution and Application to Sea Level Reconstruction

MORPHOLOGICAL VARIATION WITHIN AND BETWEEN NATURAL POPULATIONS OF NON‐TIDE POOL FUCUS DISTICHUS (PHAEOPHYTA) IN NEW ENGLAND1,2

ABSTRACTThe sources of morphological variation in natural populations of Fucus distichus L. ssp. edentatus (De la Pyiaie) Powell and F. distichus L. ssp, evanescens (C. Agardh) Powell from New England were evaluated. Individuals from different populations were morphologically distinct as judged by population means and analysis of variance. A correlation between the plant's form and its habitat was established by field observation. The broadest material grows in calm estuarine habitats, while the narrowest plants occur in exposed, open coastal areas. Major differences in morphology also appear seasonally. In addition, microhabitat factors such as exposure to wave action and elevation explain some morphological variation. Cultured germlings from distinct populations of “evanescens” and “edentatus” type plants were outplanted to an experimental garden in order to ascertain whether the variation was heritable or environmentally induced. The latter experiments indicate that major differences in morphology are genetically determined.