Intertidal Beach Research Articles

Diversidad de diatomeas bentónicas marinas en un ambiente ligeramente enriquecido con elementos potencialmente tóxicos

Diatoms are well recognized as indicators of contamination by heavy metals whose effects may alter the structure of benthic diatom assemblages. The southern beaches of Bahía La Ventana, Baja California Sur, Mexico are supplied with sediments that are naturally or anthropogenically enriched with potentially toxic elements. Thus, we carried out a geochemical assessment for trace elements in the intertidal beach sediments and we measured diversity of benthic diatom assemblages found in the intertidal sediments and on subtidal rocks. Sampling was done in March, June and September 2012. Chemical analysis was performed using acid digestion using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) for determining the concentration of 17 elements, and their Normalized Enrichment Factor values were estimated. Low to moderately degrees of enrichment for Strontium (Sr), Antimony (Sb) and Barium (Ba) were detected. Diatom taxa were identified using optic microscopy. Diversity values (species richness, dominance and evenness) were calculated. Diatom assemblages showed a high species richness with 182 taxa (species and varieties), including 30 new records for the region and 14 for Mexican waters. These, together with the high estimated values of diversity (H', J', λ) characterize a typical assemblage of benthic marine diatoms.

Evaluating shoreline identification using optical satellite images

Abstract A technique to extract the shoreline location from optical satellite images has been developed and evaluated for the case study site of Progreso, Yucatan, Mexico. A novel method to extract a satellite-derived shoreline (SDS) was developed ensuring the maximum contrast between sea and land. The area under investigation is an 8 km length of shoreline that faces north into the Gulf of Mexico. The SDS was validated using quasi-simultaneous in situ shoreline measurements, both adjusted to equal water levels. In situ shoreline measurements recorded the instantaneous shoreward extent of the wave run-up when walking along the beach. The validation of SDS revealed that the SDS is located consistently seawards of the in situ shoreline, explained by: a) the water depth that optical satellite image requires to identify a pixel either as sea or land, and b) the shoreward extent of the wave run-up. The overall distance between SDS and in situ shoreline is 5.6 m on average with a standard deviation of 1.37 m (in the horizontal) over 8 km of shoreline. Confidence bounds considering the shoreward extent of the wave run-up, inter-tidal beach slope variation and tidal uncertainty were computed to assess the accuracy of the SDS. The SDS has been shown to be capable of detecting shoreline changes of less than 10 m and abrupt changes due to storms. The success of our method suggests that it should be applicable to other locations, after adapting the confidence bounds to the beach conditions.

Shoreline Armoring Impacts and Beach Restoration Effectiveness Vary with Elevation

Abstract Removal of shoreline armoring can potentially restore lost biological functions to intertidal beaches and increase connectivity between aquatic and terrestrial realms. Conceptual models are needed, as ecologists, managers, and engineers are all concerned with finding ways to restore natural aspects to shoreline features that are stable and resilient in the face of global climate change and sea level rise. We identify the main effects of armoring on shoreline biota, examine the ecological response of a restored site where a seawall was removed, and use this to form a conceptual basis for the importance of elevation on armoring effects and restoration potential. Restoration completed in February 2005 at Seahurst Park (Puget Sound, Washington, United States) included seawall removal and creation of a beach. We monitored the site over seven years before and after restoration and compared invertebrate assemblages to a reference beach, spanning four elevations. We present a conceptual model illustratin...

Influence of Physicochemical Parameters on Burrowing Activities of the Fiddler Crab Uca tangeri at the Huelva Coast (Southwest Spain): Palaeoichnological Implications

Populations of fiddler crabs (Uca tangeri) occupy several marginal-marine environments of the Huelva coast of Southwest Spain. Associated with these organisms are large, open burrows that represent domiciles recognized by numerous circular apertures. Ichnological analysis reveals variations in features of the biogenic structures between and through different marginal-marine environments, including an intertidal sandy beach and a salt-marsh setting into an estuary zone. We hypothesized that the observed variations in burrows of Uca tangeri related to changes in particular physicochemical parameters in the overall habitat. Herein the possible relationship between the ichnological features of burrow crabs (density and diameter of aperture) and selected physicochemical factors (pH, temperature, sediment texture, grain size, firmness, and depth of ground water level) are treated. The obtained results in two selected areas where several transects were conducted suggest a variable relationship, with several parameters showing a weak influence on the burrowing behaviour (e.g., pH, and temperature), while others reveal a major important (e.g., firmness and depth of the ground water level). These results are relevant to palaeoichnological analyses regarding the behavior of trace fossil producers, the relationship between palaeoenvironmental limiting factors and burrow features, and to the improvement of characterizations regarding substrate-controlled ichnofacies.

Contamination and Recovery of Commercially-Reared Mussels Exposed to Diesel Fuel from a Sunken Fishing Vessel

ABSTRACT Following the sinking of a derelict fishing vessel near a commercial mussel farm in Penn Cove, Washington, mussels ((Mytilus trossulus), suspended 1-3 m below the sea surface, were sampled to determine if they were contaminated with diesel fuel and if so, how long it took for the contamination to depurate. Composite mussel samples were collected from 6 culture floats and two intertidal beach stations on four occasions and analyzed for 43 polycyclic aromatic hydrocarbons (PAH43), and a suite of alkanes and petroleum biomarkers. Mussel mean total PAH43 concentrations in μ/kg (parts per billion, ppb) dry weight (dw), declined from 6462 on day 5; to 4574 on day 51; 2615 on day 186; and 1097 one year later. A market sample from the same commercial operation collected January, 2012 and analyzed by the Battelle Pacific Northwest National Laboratory had a value of 839 ppb dw for the sum of 42 PAHs. The affected mussels required between 6 and 12 months to return to this total PAH concentration putative background. The whole-soft tissue total PAH43 half-life was about 5 months, far longer than the days or few weeks expected based on past literature. During the incident the commercial mussel grower voluntarily shut-down harvest, and on May 15, the Washington Department of Health (WA DOH) closed all of Penn Cove to both commercial and recreational harvest. Although individual PAH concentrations never exceeded thresholds for human consumption, samples did not initially pass sensory testing. The Penn Cove commercial and recreational harvesting was subsequently re-opened in stages to give the shellfish time to depurate and return to an untainted state. Additionally, all the concentrations of total PAHs measured in Penn Cove float and shoreline mussels during this study were within the range of concentrations reported in mussels from other monitoring sites in Puget Sound and other marine coastal areas of Washington. This relatively simple but sustained monitoring effort showed that submerged as well as inter-tidal bivalves can be contaminated by a nearby diesel spill, and that recovery may take longer than generally expected.

Morphodynamic characterization of beaches on a Pacific atoll island: Tetiaroa, French Polynesia

Jeanson, M., Anthony, E.J., Etienne, S., Dolique, F., 2014. Morphodynamic characterization of beaches on a Pacific atoll island: Tetiaroa, French Polynesia. In: Green, A.N. and Cooper, J.A.G. (eds.), Proceedings 13th International Coastal Symposium (Durban, South Africa), Journal of Coastal Research, Special Issue No. 70, pp. 176–181, ISSN 0749-0208.Beach profile types and wave characteristics were monitored in April 2013 on the small islet of Onetahi in the south Pacific coral reef atoll of Tetiaroa, French Polynesia, with the aim of characterizing atoll islet beach morphodynamics. Twelve beach profiles were each surveyed using a theodolite, and water levels and wave characteristics measured over four semi-diurnal tidal cycles using four miniature pressure sensors deployed in the subtidal zone. Water levels corresponded to a very narrow microtidal range (~0.2 m). Wave heights were extremely low throughout (<0.15 m), and spectral decomposition showed a mix between gravity and infragravity energy. The latter dominant at high water, whereas energy was virtually nil at low tide. The wave characteristics, which reflect significant filtering of large Pacific waves by the atoll reef, were not in phase with the intertidal beach morphology. These were interpreted as largely inherited from differential exposure to higher-energy events that occasionally impacted the atoll, notably Cyclone Oli in February 2010. Sand aprons in the lagoon, moving from the eastern to the southern and ultimately the western shores of the island in response to wave pumping, locally enhance build-up of the lower beach where shoreline orientation changes. Confrontation of these observations with long-term islet shoreline trends identified by Le Cozannet et al. (2013) suggests that high-energy event-scale changes and daily background beach cosmetic changes associated with subtidal sand apron mobility, and intertidal swash reworking during the narrow tidal excursion are embedded in long-term morphological stability likely hinged on sand circulation around the islet.

Intertidal beach classification in infrared images

ABSTRACT Hoonhout, B.M., Baart, F., Van Thiel de Vries, J.S.M. 2014. Intertidal Beach Classification in Infrared Images. In: Green, A.N. and Cooper, J.A.G. (eds.), Proceedings 13th International Coastal Symposium (Durban, South Africa), Journal of Coastal Research, Special Issue No. 70, pp. 657–662, ISSN 0749-0208. Digital imagery is a powerful data source for coastal monitoring, maintenance and research. It provides high-resolution measurements in both time and space. The size and resolution of long-term imagery datasets provide great opportunities, but also pose problems of tractability in the data analysis. In order to fully use the possibilities of these datasets, reliable and automated classification of images is essential. This paper discusses an automated classification approach based on Conditional Random Fields (CRF). The algorithm is applied in pixel space only. Therefore it does not rely on in-situ measurements, nor is there a need for image rectification. The algorithm consists of three steps:...

Morphodynamic variability of high-energy macrotidal beaches, Cornwall, UK

Abstract Spatial data collected over three years are presented to assess the extent of morphological variability under seasonal and storm waves on two high-energy macrotidal beaches on the north Cornish coast. Of particular interest was the degree to which the beaches displayed bar/rip morphology and a novel approach to quantify the three-dimensionality of the beach based on the curvature of the bottom contours is adopted to identify and classify the three-dimensional beach response to changes in the dominant forcing conditions. Morphologically, the beaches range from dissipative to intermediate and are characterised by low tide bar/rip morphology which plays a key role in the nearshore dynamics and beach safety. Real-time kinematic (RTK) GPS surveys were undertaken using an all-terrain vehicle to measure the three dimensional (3D) morphology. In addition, nearshore wave data, in-situ hydrodynamic measurements, local tide gauges and Argus video data allowed detailed analysis of process–response mechanisms for long term (yearly); seasonal (monthly); storm (weekly/daily); and tidal (hourly) morphological behaviour. Both sites exhibited net long term accretion derived from the intertidal beach volume. Throughout the survey period, inter-site similarity in beach response was observed in response to storm waves, yet coupling between the seasonal wave climate and the beach morphology was not evident at either of the sites. Increased wave conditions (exceeding Hs = 4 m) during sustained storm events (> 50 h) led to offshore transport from the beachface to the subtidal bar region. Post-storm recovery was characterised by onshore transport and the development of substantial 3D low tide morphology. Under normal wave conditions (Hs = 1.6 m), the dominant 3D features smoothed out as channels in-filled and bar prominence reduced over a period of 2–3 months. Overall, the beaches exhibited a significant storm-dominated morphological response cycle, unlike the more familiar winter/summer seasonal response.

ZONATION AND DENSITY OF INTERTIDAL COMMUNITIES AT COASTAL AREA OF BATU HIJAU, SUMBAWA

Characteristics of coastal tidal areas of Batu Hijau vary from sandy substrate type, sandy to rocky reef with a wide expanse of intertidal ranges from 100 meters to 350 meters. To find out zoning intertidal community,the observation conducted at five locations intertidal beach, each consisting of three zones: the high tide, middle tide and low tide. Living structure in tidal areas of coastal Batu Hijau, Sumbawa consists of the main communities and associated biota. The main intertidal community composed of coral, seagrass, algae, and other fauna, while the intertidal biota associated with tidal habitat consists of a group of molluscs, echinoderm, crustacean, worms and fish. Distribution of intertidal communities formed three zones consisting of (1) seagrass (21.3%) in the upper zone (high tide), (2) algae (35.5%) in the central zone (mid tide), and (3) coral (28.5%) and algae (42.5%) in the lower zone (low tide). The main groups of biota in the form of tidal zoning system consisting of two groups of molluscs (51.12%) in the upper zone, while the echinoderms that predominate in the central zone (36.96%) and lower (66.89%). No significant differences between the structure and composition of marine intertidal communities in September 2011 (rainy season) and April 2012 (dry season). Keywords: intertidal (tidal), percent cover, density, community, biota

ZONATION AND DENSITY OF INTERTIDAL COMMUNITIES AT COASTAL AREA OF BATU HIJAU, SUMBAWA

&lt;p&gt;Characteristics of coastal tidal areas of Batu Hijau vary from sandy substrate type, sandy to rocky reef with a wide expanse of intertidal ranges from 100 meters to 350 meters. To find out zoning intertidal community,the observation conducted at five locations intertidal beach, each consisting of three zones: the high tide, middle tide and low tide. Living structure in tidal areas of coastal Batu Hijau, Sumbawa consists of the main communities and associated biota. The main intertidal community composed of coral, seagrass, algae, and other fauna, while the intertidal biota associated with tidal habitat consists of a group of molluscs, echinoderm, crustacean, worms and fish. Distribution of intertidal communities formed three zones consisting of (1) seagrass (21.3%) in the upper zone (high tide), (2) algae (35.5%) in the central zone (mid tide), and (3) coral (28.5%) and algae (42.5%) in the lower zone (low tide). The main groups of biota in the form of tidal zoning system consisting of two groups of molluscs (51.12%) in the upper zone, while the echinoderms that predominate in the central zone (36.96%) and lower (66.89%). No significant differences between the structure and composition of marine intertidal communities in September 2011 (rainy season) and April 2012 (dry season).&lt;/p&gt; &lt;p&gt;&lt;br /&gt; Keywords: intertidal (tidal), percent cover, density, community, biota&lt;/p&gt;

Role of predation on sandy beaches: Predation pressure and prey selectivity estimated by laboratory experiments

Predation is known to play an important role in structuring communities. In rocky intertidal communities, both environmental variables and the structuring role of predation determine species zonation and distribution patterns. However, on intertidal sandy beaches, little is known on the presence and the role of predation. In this study, laboratory experiments were used to examine prey consumption, prey selectivity and predation pressure of the two main epibenthic predators, being shrimp and juvenile flatfish, present on the intertidal beach at high tide. Results show that macrobenthos is important in the diet of these epibenthic predators and that prey selectivity is present. As predation pressure on the intertidal beach is high, predation is probably an important structuring factor for the sandy beach macrobenthos community. Hence, the macrobenthos zonation pattern is likely to be steered by the combination of abiotic and biotic factors: while the upper limit of a species zone is defined by the species physiological response to abiotic environmental variables, the lower limit is defined by biotic factors such as predation pressure. Furthermore, the intertidal zone functions as an important nursery area for commercially important species like shrimp and flatfish.

Heavy metal contamination of coastal lagoon sediments: Fongafale Islet, Funafuti Atoll, Tuvalu

To evaluate contamination of coastal sediments along Fongafale Islet, Central Pacific, a field survey was conducted in densely populated, sparsely populated, open dumping and undisturbed natural areas. Current measurements in shallow water of the lagoon indicated that contaminants from the densely populated area would only be transported for a small proportion of a tidal cycle. Acid-volatile sulfides were detected in both the intertidal beach and nearshore zones of the densely populated area, whereas these were no detection in the other areas. This observation lends support to argument that the coastal pollution mechanism that during ebb tide, domestic wastewater leaking from poorly constructed sanitary facilities seeps into the coast. The total concentrations of Cr, Mn, Ni, Cu, Zn, Cd and Pb were relatively high in all of the areas except the undisturbed natural area. The indices of contamination factor, pollution load index and geoaccumulation index were indicative of heavy metal pollution in the three areas. The densely populated area has the most significant contamination; domestic wastewater led to significant contamination of coastal sediments with Cr, Zn, Cu, Pb and Cd. The open dumping area is noteworthy with respect to Mn and Ni, which can be derived from disposed batteries.

The Role of Hydrodynamic Sorting of Seston in the Nutrition of a Benthic Suspension Feeder, Spio setosa (Polychaeta: Spionidae)

AbstractNear-bed gradients in suspended particle quality and material ingested by Spio setosa were studied using an intertidal beach population in Nova Scotia. Spio builds a sand tube that allows it to feed several centimeters above the bed, where hydrodynamic sorting of horizontal transport provides low-density, high-quality organic seston. Characterization and enumeration of particles from both worm guts and ambient sediment in the field demonstrated that guts were enriched in organic mineral aggregates relative to the bed. In a laboratory flume, worms with tubes shortened to bed level received and ingested seston of significantly lower organic quality than worms feeding in intact tubes 4–6 cm above the bed. Because tube building requires ∼2.5 days, winter beach scour which removes tubes may force Spio to feed frequently at suboptimal heights above the sediment surface. The dependence of suspension feeders on organic-mineral aggregates and the tendency for these particles to incorporate estuarine pollut...

Spatial and temporal variability of metals in inter-tidal beach sediment of Mumbai, India

Nine metals were monitored in the beach sediment in Mumbai from May 2011 to March 2012 to evaluate the spatial and temporal distributions. The average heavy metal concentrations exhibited the following order: Fe > Mn > Cr > Co > Ni > Pb > Zn > Cu > Cd for the four sampling sites. The mean concentrations (± SD) of Fe, Mn, Cr, Co, Ni, Pb, Zn, Cu and Cd were estimated to be 31.15 ± 10.02gkg(-1), 535.04 ± 76.42, 151.98 ± 97.90, 92.76 ± 14.18, 67.52 ± 11.32, 59.57 ± 15.19, 54.65 ± 15.01, 32.24 ± 8.07 and 18.75 ± 1.76mgkg(-1), respectively. The results indicated that the sediments were polluted with Cd, Cr, Co and Pb due to high anthropogenic influences. Spatial variation of metals revealed that most of the metals were high in Dadar beach and low in Aksa beach. Cd was the highest contaminant metal studied with a mean contamination factor of 93.75. The pollution load indices of the studied beaches ranged from 1.63 (Aksa) to 1.91 (Dadar) and indicated that the beach sediments were polluted with heavy metals. The heavy metal contents increased in relation to monsoon, and most of the heavy metals showed significantly high concentrations in November during the post-monsoon. The statistical analysis revealed significant effect of study site on all the metals studied. Further, there was a significant difference on metal accumulation on bimonthly basis in relation to weather pattern in Mumbai beaches.

Nearshore Drift-Cell Sediment Processes and Ecological Function for Forage Fish: Implications for Ecological Restoration of Impaired Pacific Northwest Marine Ecosystems

Parks, D.; Shaffer, A., and Barry, D., 2013. Nearshore drift-cell sediment processes and ecological function for forage fish: implications for ecological restoration of impaired Pacific Northwest marine ecosystems.Sediment processes of erosion, transport, and deposition play an important role in nearshore ecosystem function, including forming suitable habitats for forage fish spawning. Disruption of sediment processes is often assumed to result in impaired nearshore ecological function but is seldom assessed in the field. In this study we observed the sediment characteristics of intertidal beaches of three coastal drift cells with impaired and intact sediment processes and compared the functional metrics of forage fish (surf smelt, Hypomesus pretiosus, and sand lance, Ammodytes hexapterus) spawning and abundance to define linkages, if any, between sediment processes and nearshore ecological function. Key findings include: (1) beach sediment characteristics of the northern Washington nearshore are complex, with strong seasonal variation in habitat form and function both within and across geomorphic habitat types; (2) loss of sediment supply to the nearshore due to in-river damming and shoreline alterations results in significantly larger and more variable beach sediment at the drift-cell scale; (3) these differences in intertidal beach sediment characteristics have implications for habitat function as indicated by less forage fish spawning habitat and lower ecological function than intact drift cells; (4) feeder bluffs are important nearshore sediment sources for forage fish spawning beaches. Forage fish may spawn at the base of feeder bluffs if appropriate sediment is available during the spawning season; and (5) seasonal rate, total volume, and grain size of sediment delivery are important for habitat suitability for fish use. Feeder bluffs therefore should be managed more conservatively and understanding and protecting their role in nearshore habitat restoration practices is a high priority.

High frequency in-situ field measurements of morphological response on a fine gravel beach during energetic wave conditions

This paper presents novel data collected over four weeks at Loe Bar, a fine gravel barrier (D50 = 3.5 mm), exposed to energetic wave conditions (Hs10% = 2.4 m). Combined remote and in-situ measurements were used to identify 3D morphological response, profile change and runup behaviour during successive energetic periods (Hs = 2.5 m). Small intertidal beach volume losses occurred under high steepness waves (H0/L0 > 0.01), but, in general, the overall beach volume was remarkably stable. In fact, the greatest morphological response was evident not in cross-shore sediment exchanges, but due to the alongshore redistribution related to the three-dimensional beach cusp system. Specifically, during energetic wave conditions the cusp morphology underwent horn growth and embayment deepening, leading to increased cusp definition. An additional explanation for the stability of the cross-shore beach profile is related to the development of the beach step. During energetic conditions and long period waves, significant deposition (c. 1 m) occurred at the top of the beach step above the still water line. The enhanced step provided a focal point for wave breaking, considerably curtailing the swash motion and reducing the runup limit, thereby providing protection to the upper beach. This study provides much needed insight into complex morphological response and runup characteristics on gravel beaches, fundamental for improved model development, and leading towards better predictive tools.

Beach morphodynamics and types of foredune erosion generated by storms along the Emilia-Romagna coastline, Italy

The objectives of this study are to examine the response of a dune and beach system on the Adriatic coastline in northern Italy to the arrival of storms, compare it with seasonal (months) and medium-term (3-year) morphodynamic change, and evaluate results predicted by the numerical model XBeach. The studied coastline stretches 4km from the Bevano River mouth to the north of the site to the township of Lido di Classe to the south, where the beach is protected by coastal structures. Fieldwork consisted of topographic profile surveys using RTK-DGPS technology (7 times over an approx. 3-year period). 103 samples of surface sediment were collected along 20 of the cross-shore profiles at 6 distinct cross-shore positions, selected on the basis of morphological beach characteristics. Data analyses of dune and beach slopes enabled the study area to be divided into 6 separate morphological zones using the spatial (longshore and cross-shore) variation of morphologies located on the backshore and intertidal beach observed in a preliminary survey of the area. Other criteria were a spatial consistency in beach slopes and/or presence/absence of intertidal morphologies identified in the aerial photographs and Lidar data. The swash zone slope did not show any significant variability for the entire area. A weak seasonal trend in the variability of the mean foredune slope was observed, with steeper slopes typically during winter and flatter slopes during summer. Analysis of grain size revealed that the beach sediment is well-sorted fine sand tending to medium, with a decreasing trend in size from the Bevano River mouth southwards towards Lido di Classe. According to the Masselink and Short (1993) classification, the natural part of the study site has an Intermediate Barred Beach (IBB) and following the Short (1999) classification, results in a modally LBT (longshore bar-trough) or LTT (low tide terrace) with a small section being TBR (transverse bar and rip). Storms are considered the main factor controlling changes in the beach and dune slope. The most significant storm was recorded in March 2010 with a peak significant wave height of 3.91m. Contrary to the seasonal dune trend, several foredune slopes were observed to flatten following this event, which can be attributed to the action of dune slumping from the already weakened dune state. Modelling of foredune erosion, using a process-based model (XBeach), reproduced the erosion of the upper beach and dune toe reasonably well, but is currently limited by the acceptable slope value for dune stability, which does not account for biotic factors (e.g. plant roots). The comparison between the storm impact categories of Sallenger (2000) and the DSF (Dune Stability Factor) of Armaroli et al. (2012) shows a very good correspondence between the effects of the winter 2008–2009 storms and the vulnerability of the dune system predicted using both classifications.

Highly toxic ribbon worm Cephalothrix simula containing tetrodotoxin in Hiroshima Bay, Hiroshima Prefecture, Japan.

In 1998, during a toxicological surveillance of various marine fouling organisms in Hiroshima Bay, Japan, specimens of the ribbon worm, Cephalothrix simula (Nemertea: Palaeonemertea) were found. These ribbon worms contained toxins with extremely strong paralytic activity. The maximum toxicity in terms of tetrodotoxin (TTX) was 25,590 mouse units (MU) per gram for the whole worm throughout the monitoring period. The main toxic component was isolated and recrystallized from an acidified methanolic solution. The crystalline with a specific toxicity of 3520 MU/mg was obtained and identified as TTX by high performance liquid chromatography (HPLC)-fluorescent detection (FLD) (HPLC-FLD), electrospray ionization-mass spectrometry (ESI-MS), infrared (IR), nuclear magnetic resonance (NMR) and gas chromatography–mass spectrometry (GC-MS). The highest toxicity of C. simula exceeded the human lethal dose per a single worm. A toxicological surveillance of C. simula from 1998 to 2005 indicated approximately 80% of the individuals were ranked as “strongly toxic” (≥1000 MU/g). Forty-eight percent of the specimens possessed toxicity scores of more than 2000 MU/g. Seasonal variations were observed in the lethal potency of C. simula. Specimens collected on January 13, 2000 to December 26, 2000 showed mean toxicities of 665–5300 MU/g (n = 10). These data prompted a toxicological surveillance of ribbon worms from other localities with different habitats in Japan, including Akkeshi Bay (Hokkaido) under stones on rocky intertidal beaches, as well as Otsuchi (Iwate) among calcareous tubes of serpulid polychaetes on rocky shores. Within twelve species of ribbon worms examined, only C. simula possessed extremely high toxicity. Therefore, C. simula appears to show generally high toxicity irrespective of their locality and habitat.

The difference in wave environments between intertidal sand beaches and mud flats

Kim, T.R and Lee, J.H., 2013. The difference in wave environments between intertidal sand beaches and mud flats.The characteristics of wave environments are studied and compared between an intertidal beach and a mud flat. The Mohang Beach is an intertidal sand beach, located on the southwest coast of Korea with tidal range of over 5 meters. Strikingly, it lies just next to the large intertidal mud flat. In order to find the wave energy difference between the intertidal sand beach and mud flat, a numerical wave model is performed with same boundary input conditions, and a wave directional spectrum is calculated at the entrance of each site. Unstructured grids for numerical wave model are used because the details of the shore orientation and topography are important to simulate wave propagation and shallow water effects in nature. It is found that the sand beach is more exposed to the wave forces than the mud flat in all wave directions. The field measurement also shows higher wave heights at the sand beach than the mud flat. The local difference of wave propagation and energy is the main factor maintaining the two adjacent environments with disparate sedimentological characteristics.

Shoreline detection: capability of COSMO-SkyMed and high-resolution multispectral images

This study aims to extract the instantaneous shoreline from remote sensing data acquired with very high resolution multispectral and SAR sensors. The capabilities of IKONOS. GeoEye and COSMO-SkyMed for shoreline detection are tested in the Venice littoral (Italy) by classifying the imagery into its land/water components. GPS measurements synchronously to the COSMO-SkyMed acquisitions are carried out along two transects at different tidal levels and used for validation of satellite derived shorelines. Finally, a collection of instantaneous coastlines at a specific tidal level is mapped for reconstructing the intertidal beach morphologic model.