A numerical study of hypothetical storm surge and coastal inundation for AILA cyclone in the Bay of Bengal

The head Bay region bordering the Bay of Bengal is highly vulnerable to tropical cyclones. Catastrophic risks from storm surge and associated inundation are quite high due to high population density in coastal areas, socio-economic conditions, and shallow bathymetry. It features the world’s largest deltaic system comprising of ‘Sunderbans’ bordered by West Bengal and Bangladesh. In a geomorphologic sense, the head Bay region is a low-lying belt comprising several barrier islands and river drainage systems, numerous tidal creeks, and mud flats having a high risk for widespread inundation. In addition, the high tidal range together with low-lying topography leads to high risk and vulnerability from storm surge inundation. During May 2009, a severe cyclonic storm Aila struck West Bengal causing enormous destruction to life and property along coastal belts of West Bengal and Bangladesh. It was the strongest pre-monsoon cyclone in the past two decades that had landfall in West Bengal. This work reports on a numerical study for hypothetical storm surge and associated inundation from Aila using the ADCIRC model. The study covers a comprehensive qualitative analysis on water level elevation and onshore inundation for West Bengal and Bangladesh regions. The estimated peak storm surge was about 4 m in the Sunderban region that propagated into all major riverine systems, inundating the river banks as well the inland areas. Numerical simulations indicate an average inland penetration distance of 350 m with a maximum of 600 m at various coastal locations in West Bengal and Bangladesh. The study emphasizes the need and importance of inundation modeling system required for emergency preparedness and disaster management.     

Predicting suitable habitat for the European lobster (Homarus gammarus), on the Basque continental shelf (Bay of Biscay), using Ecological-Niche Factor Analysis

Predicting species distribution and habitat suitability (HS) modelling, across broad spatial scales, is now a major challenge in marine ecology. The resulting knowledge is of considerable use in supporting the implementation of environmental legislation, integrated coastal zone management and ecosystem-based fisheries management. This contribution considers the identification of seafloor morphological characteristics, together with wave energy conditions, that determine the presence of European lobster (Homarus gammarus); and it predicts suitable habitats over the Basque continental shelf (Bay of Biscay), in summer. The results obtained, by applying Ecological-Niche Factor Analysis (ENFA), indicate that lobster habitat differs considerably from the mean environmental condition over the study area; likewise, that it is restrictive in terms of the range of conditions in which they dwell. The best of the environmental predictors found to be: distance to the rock substrate; Benthic Position Index; wave flux over the seafloor; and the underlying bathymetry. A habitat suitability map was produced, with a high model quality (Boyce index: 0.98 ± 0.06). The most suitable habitat for European lobster are locations at the boundary between sedimentary- and rocky-bottoms, coincident with seafloor depressions with a steep slope, with medium to high wave energy conditions, and located within a range of water depths of 35–40 m. This approach demonstrates the applicability of the method in case studies where only presence data are available, together with the inclusion of environmental variables obtained from different sources.     

Physical and numerical modelling of tsunami generation by a moving obstacle at the bottom boundary

This paper presents a study of the waves generated by a solid block landslide moving along a horizontal boundary. The landslide was controlled using a mechanical system in a series of physical experiments, and laser-induced fluorescence measurements resolved both spatial and temporal variations in the free surface elevation. During its constant-velocity motion, the landslide transferred energy into ‘trapped’ offshore-propagating waves within a narrow frequency band. The wave trapping is demonstrated by investigating the wave dispersion characteristics using a two-dimensional Fourier Transform. The first of the trailing waves broke at Froude numbers greater than or equal to 0.625. The parametric dependence of the largest-amplitude waves and the potential energy within the wave field are discussed. The experimental results were compared to the predictions of an incompressible Navier–Stokes solver with and without turbulence models. The numerical model under-predicted the measured wave amplitudes, although it accurately predicted the measured wave phasing. The turbulent model more accurately predicted the shapes of the trailing waves. Both experimental and numerical results confirmed that investigations into wave generation by submerged objects moving at constant velocity should also consider the initial acceleration of the object, as this affects the overall evolution of the wave field. The applicability of the horizontal-boundary results to more realistic field scenarios is discussed.     

Modis reflectance and active fire data for burn mapping and assessment at regional level

This paper presents an algorithm for rapid and accurate burn mapping that is applied here to the forest fires occurred in Galicia (northwest Spain) in August 2006, when nearly 930 km² were almost entirely burned over the course of eight days. The algorithm synergistically combines remotely-sensed reflectance and active fire data as measured by the MODIS (MODerate resolution Imaging Spectrometer) sensor on board Terra and Aqua NASA (National Aeronautics and Space Administration) satellites. Burned area data collected from this work was compared to official fires statistics from the Spanish Ministry of Environment and to perimeters that were derived using a high spatial resolution satellite image. In a later step, burn patches area analyzed using information from the National Forest Map (1:50,000) and some Geographical Information Systems (GIS) tools.     

Land cover changes in the Caroni Swamp Ramsar Site, Trinidad (1942 and 2007): implications for management

Caroni Swamp Ramsar Site, the largest mangrove dominated wetland in Trinidad and Tobago, continues to be impacted by human activities. This study examines changes in land cover and land use from 1942 to 2007 using remote sensing technology, geographic information systems (GIS) and extensive field surveys. Land cover maps were produced for 1942, 1957, 1986, 1994, 2003 and 2007 from aerial photos and high resolution satellite imagery. Caroni Swamp’s hydrology was altered in the 1920’s to facilitate rice cultivation. This resulted in the formation of large tracts of freshwater marsh. From 1942 to 1957, freshwater marsh and agriculture lands increased, but after this period there was a steady decline in both, as freshwater was diverted away from the wetland and salt water intruded further inland. Although mangrove forest was cleared for built development, its coverage has consistently increased in the Swamp from 1957, with the exception of 2003 when there was a decrease by less than 100 ha. This is in contrast to most areas in the tropics where mangrove coverage continue to decline. In this case, the mangrove trees are out-competing/shading marsh vegetation, causing shift in the wetland communities. In the Caroni Ramsar Site, the natural wetland communities generally increased from 1942 to 2003, but declined in 2007, as built development more than doubled. The paper provides spatial coverage, and quantifies land cover from 1942 to 2007. It also identifies reasons for the changes in land cover and uses, and the implications for management.     

Modeling the interaction between tides and storm surges for the Taiwan coast

An unstructured grid, two-dimensional hydrodynamic model was established and applied to the coast of Taiwan to investigate the tide-surge interaction. Tidal elevations at the open boundaries coupled with a global ocean tidal model and the meteorological conditions using a cyclone model are used to drive the model. The model was calibrated and verified with the observed tidal levels at six tidal stations for seven typhoon events to ascertain the capability and feasibility of the model. The results show reasonable agreement between the simulated and observed tidal levels. The validated model was then applied to probe the influence of tide-surge interaction on phase, water levels, and storm surge height. We found that the tide-surge interaction influenced both the magnitude and timing of the surge, which depended on the typhoon path. The storm surge heights at different tidal stations were significantly influenced by wind stresses and directions. The water level rise due to the storm surge during high tide was greater at neap tide than at spring tide. Changing tidal ranges altered the prediction of the surge enough to induce the changes in peak water levels.     

Islands at bay: rising seas,eroding islands,and waterbird habitat loss in Chesapeake Bay (USA)

Like many resources in the Chesapeake Bay region of the U.S., many waterbird nesting populations have suffered over the past three to four decades. In this study, historic information for the entire Bay and recent results from the Tangier Sound region were evaluated to illustrate patterns of island erosion and habitat loss for 19 breeding species of waterbirds. Aerial imagery and field data collected in the nesting season were the primary sources of data. From 1993/1994 to 2007/2008, a group of 15 islands in Tangier Sound, Virginia were reduced by 21% in area, as most of their small dunes and associated vegetation and forest cover were lost to increased washovers. Concurrently, nesting American black ducks (Anas rubripes) declined by 66% , wading birds (herons-egrets) by 51%, gulls by 72%, common terns (Sterna hirundo) by 96% and black skimmers (Rynchops niger) by about 70% in this complex. The declines noted at the larger Bay-wide scale suggest that this study area maybe symptomatic of a systemic limitation of nesting habitat for these species. The island losses noted in the Chesapeake have also been noted in other Atlantic U.S. coastal states. Stabilization and/or restoration of at least some of the rapidly eroding islands at key coastal areas are critical to help sustain waterbird communities.     

Sexual selection and competitive mating success of males guppies (Poecilia reticulata) from four Trinidad populations

Summary Luyten and Liley (1985) obtained evidence that in populations of Trinidad guppies from two clear headwater streams, where Rivulus harth is the major aquatic predator, selection has favored visual aspects of male mating behavior — display activity and conspicuous coloration. Males in two lowland turbid stream populations, with numerous aquatic predators, were found to rely more heavily upon non-display components of courtship. In this study males of the four populations were placed in competition in clear water for mating with females of the same populations. Males of two populations were allowed to compete in turbid water. Mating success was determined on the basis of the frequency of insemination and the proportion of sperm attributable to males of the competing populations. The sperm of competing males were identified by radioisotope labelling and autoradiographic techniques. Males from headwater populations were more successful than lowland males in mating with headwater females in clear water. There was no difference in mating success of headwater and lowland males in competition for lowland females in clear water, but in turbid water lowland males were more successful in inseminating lowland females. Males were more successful in mating with females of their own population when the two headwater population were in competition. The results are consistent with the hypothesis that conspicuous coloration and high frequency and duration of display are adaptations to clear water conditions, and that non-display tactics are adapted to turbid water. Evidence of intrapopulation preferences suggest that male traits and female sexual responses in the guppy have evolved in parallel as predicted by sexual selection theory.     

Predator stimuli and calling behavior of Carolina chickadees (Poecile carolinensis), tufted titmice (Baeolophus bicolor), and white-breasted nuthatches (Sitta carolinensis)

Evidence from different chickadee species (Poecile genus) indicates that birds can modify the note composition of their “chick-a-dee” calls in the presence of predator stimuli. Here, we tested the effects of predator models and the distance of those models on calls of three species foraging together at feeding stations: Carolina chickadees (Poecile carolinensis) and tufted titmice (Baeolophus bicolor), both members of the Paridae family, and white-breasted nuthatches (Sitta carolinensis), a member of the Sittidae family. Model and distance affected seed-taking rates in all three species. “Chick-a-dee” calling rates were higher in the predator context for both chickadees and titmice, but we detected no predator context effects on “quank” call rates for nuthatches. Predator and distance contexts affected acoustic parameters of notes of the “chick-a-dee” calls of chickadees and titmice; no such effects were detected for nuthatch “quank” calls. These results suggest species differences in encoding of information in the primary social calls of these three species that commonly occur in multi-species flocks. Chickadees and titmice are “nuclear” species and nuthatches are “satellite” species, and these different roles might be related to the differences in vocal signaling that we detected.     

Development and phenology of Ecklonia radiata at two depths in Goat Island Bay,New Zealand

Ecklonia radiata (C. Ag.) J. Ag. growing in Goat Island Bay, New Zealand produced up to 6 kg dry weight of tissue m^-2 yr^-1 in dense populations at 7-m depth. Half this tissue and an unknown amount of exudates were sloughed or torn off. Tissue production at 15 m was 0.3 to 0.5 kg m^-2 yr^-1. At this depth the plants grew only half as fast as in shallow water and the population density was decreased. Approximately 20% by weight of tissue produced at 7 m and 10% of that at 15 m was reproductive tissue. At both depths the elongation rate and percentage of water in stipes varied with stipe size. Initial sorus formation was related to plant size and not to age. Seasonal fluctuations in growth rate, haptera formation, frond size and sporulation were delayed in plants in deeper water.     

Response of Ecklonia radiata (Laminariales) to light at 15°C with reference to the field light budget at Goat Island Bay,New Zealand

Gametophytes of Ecklonia radiata (C.Ag.)J.Ag. grew in culture at 15°C under daily quantum doses ranging from 0.86 to 360 cE m^-2. Growth rates increased with quantum doses up to 40 cE m^-2 d^-1, then reproduction began and the relative growth constant declined while ovum release came earlier with increasing light up to about 100 cE m^-2 d^-1. Above 100 cE m^-2 d^-1 there were no consistent trends with increasing light, except that at the higher quantum doses, fertile female plants had fewer and larger cells and therefore fewer potential ova. Reproduction varied with daily quantum dose rather than with daylength. Given the same daily dose, plants grew fastest in low photon flux density, long daylength conditions. Gametophytes grown in the field developed at similar rates to those in culture. Gametophytes survived seven months of darkness at 10°C but died after one week of darkness at 20° to 23°C. Sunlight of 1 000 E m^-2 s^-1 was fatal to gametophytes and to sporophytes under 2 mm long after 10 to 15 min. Light budgets were prepared for plants growing at 7-and 15-m depths from 1976 to May 1980 in Goat Island Bay, New Zealand (Lat.36° 16S, Long. 174° 48E). Underwater light was measured under various environmental conditions. Relationships between transmission of light through the sea, data from diving visibility records and continuous surface meteorological records were studied. Approximations were made of the average percentage of surface light transmitted to 7 and 15 m over half-monthly periods. By applying these average transmittance values to the records of surface incident light, the average daily quantum doses were calculated. Light on open bottom in Goat Island Bay may sometimes be limiting for gametophyte reproduction in winter at 15-m depth. At depths less than 7 m, summer photon flux densities may reach damaging levels.     

Conservation Applications of Astronaut Photographs of Earth: Tidal-Flat Loss ( Japan), Elephant Effects on Vegetation (Botswana), and Seagrass and Mangrove Monitoring (Australia)

Abstract: National Aeronautics and Space Administration ( NASA) photographs taken by astronauts from low Earth orbit can provide information relevant to conservation biology. This data source is now more accessible because of improvements in digitizing technology, Internet file transfer, and availability of image processing software. We present three examples of conservation-related projects that benefited from the use of astronaut photographs. First, NASA scientists requested that astronauts photograph the area of the controversial Isahaya Bay reclamation project in Japan. Japanese researchers used photographs from before and after the reclamation as a tool for communication with the public about the effects of tidal-flat loss. The newly acquired images and the availability of high-resolution digital images from NASA archives provided timely public information on the observed changes. Second, we digitally classified and analyzed a Space Shuttle photograph of Chobe National Park in Botswana to identify the locations of woodlands affected by elephants. Field validation later confirmed that areas identified on the image showed evidence of elephant damage. Third, we used a summary map from intensive field surveys of seagrasses in Shoalwater Bay, Australia, as reference data for a supervised classification of a digitized photograph taken from orbit. The classification distinguished seagrasses, sediments, and mangroves with accuracy approximating that in studies using other satellite remote-sensing data. Astronaut photographs are in the public domain, and the database of nearly 400,000 photographs from the late 1960s to the present is available at a single searchable location on the Internet (  http://eol.jsc.nasa.gov/sseop ). These photographs can be used by conservation biologists as a source of general information about the landscape and for quantitative mapping.     

New observations of the gills of Placopecten magellanicus (Mollusca: Bivalvia), and implications for nutrition

The internal anatomy and microanatomy of the gill of Placopecten magellanicus Gmelin collected in May and November 1985 from Chamcook Bay, New Brunswick, Canada, was studied using thin-section light microscopy and transmission electron microscopy. Most of the spurs show no evidence of organic union, and hence do not participate in vascular exchange. However, the dorsal bend shows both ciliary and organic interfilamentar union. The internal structure and the hemocytes of the dorsal respiratory expansion are presented. The epithelium consists of three distinct cell types, bounded by apical microvilli. All regions of the gill contain an epithelial basal membrane, which is greatly convoluted in the interconnecting vessels of the dorsal respiratory expansion. The significance of these observations is discussed in relation to possible roles in respiration, transmembrane transport and nutrition. The apical surface of all ciliated cells is covered with an acellular matrix composed of clear spherical vesicles, which may serve a mechanical function for which mucus would be unsuited. The significance of the abundance of mucocytes on the abfrontal surface of the principal filaments is discussed in terms of the escape response of pectinid bivalves.     

Resting eggs of zooplankton (Copepoda and Cladocera) from the Kiel Bay and adjacent waters (southwestern Baltic)

Resting eggs of four species of calanoid copepods and three species of cladocerans were collected from sediments up to 5cm depth from the Kiel Bay and adjacent waters in the southwestern Baltic Sea during April–May 1994. All but one species of cladoceran was successfully hatched/reared in the laboratory. In the Kiel Bay, egg abundances varied from 1.8x10⁵ to 7.4x10⁵ m^-2. Hatching success of copepod eggs collected from all depths was high (49 to 94%), but was 0 to 79% for cladoceran eggs. Darkness did not seem to affect hatching. Eggs found in the 4 to 5 cm layer of sediment were estimated to be about 15 yr old, showing the presence of an egg bank in the Baltic. Formation of resting eggs may be a genetic trait acquired during the ice ages.     

New observations of the gills of Placopecten magellanicus (Mollusca: Bivalvia), and implications for nutrition

The organization, general anatomy, and surface microanatomy of all regions of the gills of a representive bivalve mollusc, Placopecten magellanicus Gmelin, were studied using stereo-microscopic, histological, and scanning electron microscopic techniques. Individuals were collected in May and November 1985 from Chamcook Bay, New Brunswick, Canada. In addition to correcting earlier accounts of this structure, a number of new observations are reported. The orientation of the ciliated spurs appears to be responsible for the sinusoidal arrangement of the gill filaments. Micrographs showing the structure of the dorsal respiratory expansion are presented. The entire abfrontal surface of the principal filament, including the dorsal respiratory expansion, is densely ciliated and mucosecretory. These characteristics may aid in the establishment of a respiratory current and in the prevention of gill damage during escape responses. All nonciliated regions of the gill filaments are covered with microvilli, thus greatly increasing the surface area of the gill. The feeding mechanism is discussed in relation to the dorsal and ventral ciliated tracts. Symbiotic ciliate protozoans are constantly dislodged from the gill filaments and transported via the ventral mucus string to the buccal region. The nutritional implications of these observations are discussed.     

Tissue distribution and excretion of 99mTc-disofenin in three marine species: Pleuronectes americanus (winter flounder), Homarus americanus (lobster), and Mya arenaria (soft-shell clam)

To determine the pharmacokinetics of a small lipophilic molecule in vivo, the distribution and accumulation of ^99mTc-radiolabelled disofenin (diisopropylacetanilide iminodiacetic acid) were traced during 1991–1992 by scintigraphy and gamma well counting in winter flounder (Pleuronectes americanus collected from Boston Harbor and Long Island Sound in 1992), lobsters (Homarus americanus collected from Massachusetts Bay in 1991), and soft-shell clams (Mya arenaria purchased in 1991). The agent was distributed throughout the bodies of lobsters within 12 s, throughout flounder within 40 s, and throughout clams within 2 min. It was concentrated most strongly by the liver of flounder, which contained 61.2±7.8% of the injected dose within 1 h of injection, and by the lobster hepatopancreas. Accumulation also occurred in the flounder kidney, lobster antennal glands, and the kidney and pericardial glands of clams. The compound was rapidly excreted from the flounder liver into the gall bladder, and from the lobster hepatopancreas into the stomach. The data suggest its excretion from the lobster antennal glands and clam kidneys. The rate of clearance of disofenin from the body varied among species: 99±2.1% of the initial dose remained in flounder sampled 16 to 24 h after injection, compared to 80.5±7% remaining in the lobster after 15 h, and 87.4±5.9% remaining in clams after 27 h. The clearance rates in flounder and lobster are considered to be minimum values because of the lack of gut activity in unfed individuals. Overall, these in vivo tracer studies establish the utility of scintigraphy for assessing the uptake and excretion of a lipid soluble compound in different taxa, and may be applicable for evaluating disease and/or environmental effects on organ function in marine animals.     

Organic content and biomass of abyssal holothuroids (Echinodermata) from the Bay of Biscay

The levels of ash, lipid, carbohydrate, protein and calories in the body walls of 3 abyssal holothuroids of the Bay of Biscay [Benthogone rosea Koehler, Paelopatides gigantea (Verrill) and Psychropotes longicauda Theel] are similar to those found in the body walls of shallow-water holothuroids. The biomass of abyssal holothuroids in terms of calories comprises an important fraction of the total biomass in the deep sea; at 2 000 m depth, the holothuroids correspond to one-sixth of the total biomass. However, the numerical and caloric densities of abyssal holothuroids are 4 orders of magnitude less than those of shallow-water holothuroids, although the sizes and caloric contents of individuals are of similar magnitude.Contribution No. 742 of Centre Océanologique de Bretagne     

Nitrogen versus phosphorus limitation in a subtropical coastal embayment (Moreton Bay; Australia): Implications for management

An approach combining nutrient budgets, dynamic modelling, and field observations of phytoplankton and nitrogen (N₂)-fixing Lyngbya majuscula following changes in wastewater N loads, was used to demonstrate that Moreton Bay is potentially phosphorus (P) limited. Modelling and nutrient budgeting shows that benthic N-fixation loads are high, allowing the system to overcome any potential N-limitation. Phytoplankton biomass has shown little change from 1991 to 2006 in the sections of Moreton Bay most impacted by wastewater effluents, despite a large reduction in wastewater N loads from 2000 to 2002. This is consistent with modelling that also showed no reduction in primary productivity associated with reduced N loads. Most importantly, there have been rapid increases in the occurrence of N-fixing L. majuscula in Moreton Bay as wastewater P loads have increased relative to wastewater N loads. This is also consistent with modelling. This work supports the premise that there may be fundamental differences in nutrient limitation of primary production between subtropical and temperate coastal systems due to differences in the importance of internal nitrogen sources and sinks (N-fixation and denitrification). These differences need to be recognised for optimum management of coastal systems.     

Arsenic (As), antimony (Sb), and lead (Pb) availability from Au-mine Technosols: a case study of transfer to natural vegetation cover in temperate climates

Soils from old Au-mine tailings (La Petite Faye, France) were investigated in relation to the natural vegetation cover to evaluate the risk of metals and metalloids (Pb, As, Sb) mobilizing and their potential transfer to native plants (Graminea, Betula pendula, Pteridium aquilinum, Equisetum telmateia). The soils are classified as Technosols with high contamination levels of As, Pb, and Sb. The single selective extractions tested to evaluate available fraction (CaCl₂, acetic acid, A-Rhizo, and DTPA) showed low labile fractions (<5 % of bulk soil contents), but still significant levels were observed (up to 342.6 and 391.9 mg/kg for As and Pb, respectively) due to the high contamination levels of soils. Even at high soil contaminations (considered as phytotoxic levels for plants), translocation factors for native plants studied are very low resulting in low concentrations of As, Sb, and Pb in their aerial part tissues. This study demonstrates the important role of (1) native plant cover in terms of “stabilization” of these contaminants, and (2) the poor effectiveness of extraction procedures used for this type of soil assemblages, i.e., rich in specific mineral phases.