Middle Island Research Articles

Vendian tectono-magmatic events in mantle ophiolitic complexes of the polar Urals: U-Pb dating of zircon from chromitite

Geological and isotopic evidence of Late Vendian magmatic events in restitic ultramafic mantle rocks of the Voikar-Syn’ya ophiolitic massif are considered and correlated with events at the eastern margin of the East European Platform. The geological and isotopic data show that the ophiolitic complexes of the Polar Urals were formed during several stages. The percolation of melts through peridotites was recorded in the newly formed mineral assemblages, for example, olivine + chromite ± zircon. Zircon crystallized from the residual fraction of the evolved basic melt that impregnated peridotite. The active interaction of hot restitic harzburgite with the migrating melt resumed repeatedly and could have led to the formation of several generations of chromite-bearing dunite. An important geological inference can be made from this suggestion: There is a high probability that isotopic markers of different age have been retained in restitic mantle complexes of ophiolites. The U-Pb dating of zircons with a SHRIMP-2 ion microprobe has shown that the isotopic age of seven grains is 585.3 ± 6 Ma (MSWD is 0.036 and the probability of concordance is 0.85). The obtained age of zircon from chromitite marks a Vendian tectonomagmatic event that occurred in the upper mantle of the transitional zone between the East European Plate and the oceanic basin. The island-arc complexes of the Polar Urals developed on the tectonically juxtaposed fragments of the Early Paleozoic and pre-Paleozoic oceanic crust. These crustal rocks were reworked during younger magmatic events related to the origin of the Middle Paleozoic island arcs. As a result, the rocks that formed in different geological epochs were locally retained in the restitic mantle complexes of a spatially indivisible ophiolitic association.

Some biological parameters of the Mediterranean sand smelt Atherina (Atherina) hepsetus, Linnaeus, 1758 (Pisces: Atherinidae) from the middle eastern Adriatic (Croatian coast)

Data on the length-weight relationship, age, growth, sex ratio and mortality were analysed for the Mediterranean sand smelt, Atherina (Atherina) hepsetus L. (total = 2805 ; males = 1258 ; females = 1547) collected in the eastern middle Adriatic island area during the reproductive period (February to April) in 2002. The total length of sampled specimens ranged from 3.8 to 14.5 cm and the weight from 0.28 to 22.39 g. The overall sex ratio was 1.23 : 1 in favour of females, significantly different from the expected 1 : 1 ratio (χ 2 = 29.76 ; P 13.4 cm were females. The oldest collected male and female specimens were 5 years old. The von Bertalanffy growth formula was estimated for females (L = 15.79 (1-e0.43(t+0.049)) and males (L = 15.25 (1-e0.43(t+0.018)). The power values (b) of the length-weight relationship were very similar for both sexes (b = 3.14) and indicated a slightly allometric growth. The instantaneous rates of mortality for all collected fish were Z = 1.44 year1 ; M = 0.94 year1 and F = 0.50 year1. The exploitation ratio was E = F/Z = 0.35. The value for M is highly uncertain, however, as well as those values for F and E.

RECENT COLONIZATION OF MIDRIFF ISLANDS, GULF OF CALIFORNIA, MEXICO, BY FERAL HONEYBEES, APIS MELLIFERA

Honeybees (Apis mellifera) in the Americas are an introduced species that has been established throughout most of the hemisphere for decades or centuries. An exception is the uninhabited Midriff islands in the Gulf of California. Except for the near-shore Isla Tiburón, historical evidence indicates that feral honeybees did not successfully colonize the Midriff islands until about the early 1990s. Today, colonies are well established on the major islands of Tiburón, San Esteban, San Lorenzo, and Ángel de la Guarda, and honeybees forage on 2 smaller islands: Las Ánimas (San Lorenzo Norte) and Mejía. There is no evidence of colonization or foraging on the small and floristically impoverished islands of Salsipuedes, Rasa, Partida Norte, and San Pedro Mártir. Whether the honeybees are Africanized remains undetermined, but is likely in view of the overwater distances to the islands and time of their arrival. Whether Africanized or not, honeybees are an invasive exotic species that could significantly disrupt the largely natural Midriff island ecosystems.

Spatial distribution and species composition of small pelagic fishes in the Gulf of California

Traditional regionalization methods in fisheries based on provinces or major fishing areas, includes large and arbitrary grids in which basic statistics or inferences on distribution or abundance are made. We describe a method for regionalization and analysis of fishing activities for small pelagic fisheries in the Gulf of California based on spatial patterns of landing and catch data in a Geographic Information System (GIS) environment. A fisheries database from logbooks with spatial attributes from October 2002 to June 2007 was analyzed. Landings and catching data were transformed to a Weighted Region Index (WRI) by using fuzzy logic operators. The WRI revealed fishing action centers characterized by areas with the highest WRI values, and a hierarchy for the relative importance of the regions was established. Guaymas, Desemboque de Caborca, Isla Patos, and Bahia San Rafael they were the most prominent ones. An analysis of the relative frequency of species composition showed that the Pacific sardine had an over 80 % abundance in the midriff islands, and remained as the most important in the upper gulf regions, while in the central part of the gulf, relative abundances of Pacific sardine and Northern anchovy were more balanced. Relative abundance of mackerel was significantly larger around Isla Patos than in any other place. Guaymas had the largest relative composition of Northern anchovy and the lowest values for Pacific sardine. Desemboque de Caborca showed the largest homogeneity in species relative composition. It is important to highlight that this results come from in situ data, while the results previously reported come from landing statistics by port. Therefore, the present method acknowledges the spatial differences of species by regions, additional to the traditional time series analysis.

Growth and development of captive-reared Mercury Islands tusked weta, Motuweta isolata Johns (Orthoptera: Anostostomatidae)

The Mercury Islands tusked weta, Motuweta isolata (Orthoptera: Anostostomatidae), occurs naturally only on Middle Island, a 13 ha island in the Mercury Island group, New Zealand. Growth and development were studied to support a conservation programme to establish them on two other islands and thereby reduce chances of accidental extinction. The egg incubation period was determined from 784 eggs laid by eight weta (range 6-275 eggs per female) exposed to varying temperature similar to Middle Island. Most eggs (240) hatched after 12-39 weeks but 17 eggs laid in late winter hatched after 48-63 weeks. Overall, 87% hatched between October and December, and all hatched between August and February. Egg mortality was 67% (range 50-100% for individual females). Growth and postembryonic development was observed in the laboratory at 16-18°C, and a 14 : 8 h (light : dark) photoperiod. Males and females became adult at either the 10th or 11th instar. Lengths of the head, head with jaws, pronotum, protibia, tympanal membranes, mesotibia, metatibia, metafemur, cercus, ovipositor, tusks, hypandrium and stylus are given for each instar. Tusks appeared as slight bulges on the mandibles of males at the 7th instar, and subsequently enlarged allometrically at each ecdysis. The lifespan from hatching averaged 718 ± 51 d (±95% CI) and ranged from 595 to 902 d. No significant differences were detected between the lifespans of either males or females, or weta that became adult at the 10th or 11th instar. Adult status was confirmed for one 10th instar male when it copulated with 11th instar adults. Males made multiple unsuccessful attempts to copulate with two 10th instar females and 284 eggs were found in one 10th instar female after it died. Only one 11th instar female laid eggs (83) but none hatched in the laboratory.

MHC gene configuration variation in geographically disparate populations of California sea lions (Zalophus californianus)

Major histocompatibility complex (MHC) class II DRB genotypes were examined in two geographically isolated populations of California sea lions (Zalophus californianus) (Gulf of California and California coastal Pacific Ocean). Genomic DNA from 227 California sea lions was examined using eight sequence-specific primer (SSP) pairs flanking the putative peptide-binding site. A total of 40 different Zaca-DRB genotype configurations were identified among the 227 individuals. Using SSP-PCR, significant differences were found between coastal California and Gulf of California Zalophus populations in numbers of DRB sequences per individual and configuration of sequences within individuals. Additionally, unique local patterns of MHC diversity were identified among the Midriff Island animals. These population differences are consistent with either ecologically distinct patterns of selection pressures and/or geographical isolation. The consequences of these partitioned MHC configurations at the population level are as yet unknown; however, the worldwide increase in emerging marine diseases lends urgency to their examination.

Inventory of Intertidal Marine Habitats, Boston Harbor Islands National Park Area

The intertidal zone of the 34 islands that are the Boston Harbor Islands national park area encompasses over half of the total park area, thereby representing a significant natural resource. The purpose of this study was to inventory the intertidal zone by classifying and mapping all habitats and compiling species lists for major taxonomic groups. The Boston Harbor Intertidal Classification System was developed for mapping substrate and biotic assemblage types—a system specific to the local area, but capable of application throughout the Gulf of Maine. Intertidal habitats were mapped from GPS-based field delineations. Mixed coarse, consisting of rocks, boulders, cobbles, gravel, shell, and sand, was by far the most common substrate type; however, the islands were variable with a total of 13 discrete substrate types mapped, ranging from bedrock and boulders to mud. The outer islands (e.g., Outer and Little Brewster) were dominated by rocky substrate, while islands close to the mainland (e.g., Thompson, Slate) had high percentages of fine sediments. Of the 31 biotic assemblages mapped, Mytilus edulis (blue mussel) reef was the dominant assemblage on many of the middle and Hingham Bay islands, while the outer islands had assemblages common to the more exposed rocky substrates. The species inventory recorded 95 species of invertebrates, 70 marine algae, and 15 vascular plants. The information generated from this inventory will provide a foundation for natural resource management decisions, design of a long-term intertidal monitoring program, and identification of research needs.

Diet of California sea lions, Zalophus californianus, at San Jorge Island, northern Gulf of California, Mexico, 1998–1999

The California sea lion, Zalophus californianus (Lesson, 1828), is the only resident pinniped in the Gulf of California, the largest populations inhabiting the Midriff islands and the northern gulf. San Jorge Island, in the northern gulf, has the second largest reproductive colony, and it is genetically different from other colonies in the gulf. We studied the diet of the San Jorge sea lions through scat analysis from February 1998 to March 1999. Midshipman, Porichthys sp. (mostly darkedge midshipman, P. analis Hubbs and Schultz, 1939) was the most important prey item for sea lions at San Jorge, followed by Panama grunt, Pomadasys panamensis (Steindachner, 1875), and Panama brief squid, Lolliguncula panamensis Berry, 1911. It appears that the sea lions foraged mostly on the sea bottom. The prey consumed by sea lions at San Jorge are of no commercial interest. There was little dietary overlap between California sea lions and brown boobies, Sula leucogaster (Boddaert, 1783), the most abundant ichthyophagous bird on the island.

UNIQUE ISLAND HABITATS MAY BE THREATENED BY DOUBLE-CRESTED CORMORANTS

Abstract Double-crested cormorant (Phalacrocorax auritus) populations on the Great Lakes expanded greatly during the past 2 decades. On Lake Erie, the number of breeding cormorants increased from 174 birds (87 nests) in 1979 to 26,542 (13,271 nests) in 2000. In 2000, 81% of the breeding population was on 2 western-basin islands (East Sister and Middle Islands). The plant communities on these islands represent some of the last remnants of Carolinian vegetation in Canada. Our study is the first to quantitatively assess the relationship between the distribution of nesting cormorants and forest health. On East Sister Island, 2 measures of forest cover were obtained using infrared aerial photographs and ground-based measurements of leaf area index. These measures of forest cover were correlated (rs = 0.70, P < 0.001), which validated the use of remotely sensed data to assess forest cover. Cormorant nest density was negatively correlated with tree cover on both East Sister and Middle Islands. Temporal compariso...

Annual Variability of Phytoplankton Primary Production in the Western Basin of Lake Erie (2002–2003)

Carbon fixation regulates the biological production capacity of lakes. To assess the phytoplankton production capacity of western Lake Erie, primary production was monitored in situ every other week at Middle Sister Island from spring to early autumn in the years 2002 and 2003. Physical parameters (light penetration, temperature, and dissolved oxygen), chlorophyll a, and major nutrients (total phosphorus and nitrate) were also measured. A decrease in primary production, based on monthly weighted means, was observed in summer 2003 (0.04–0.78 g C·m −2·d −1) when compared to 2002 (0.65-2.06 g C·m −2·d −1), correlating well with a reduced and more variable depth of the euphotic zone. Chlorophyll a and total phosphorus concentration, however, were higher in 2003. These data demonstrated that changes in carbon fixation are regulated by short and long term variability in the underwater light climate of the western basin of Lake Erie that are associated with wind events.

The geochemistry and sources of metals and phosphorus in the recent sediments from the Northern Gulf of California

The impact of human interventions on water and sediment fluxes from the Colorado River into the Gulf of California is still poorly understood. The erosion of the deltaic structure and the adjacent tidal flats has caused the dispersion and re-deposition of metal-rich clayey mud along the Baja California coast and alternate sediment sources are thought to have gained importance. The sediments in the Northern Gulf of California (NGC) are studied geochemically in order to determine the probable sources and sinks of sediments, metals and phosphorus in the region. Four geochemical factors are identified in the NGC: terrigenous silts and clays, biogenic carbonates, barite and phosphate. Unlike other sediments in the NGC, the Colorado River-derived silts and clays (Fe ≤ 2.8%) are characterised by their high concentrations of labile inorganic-P (269 μg g −1); in these sediments ∼27% of the bulk concentrations of P is found in the exchangeable, Fe and Mn redox-sensitive and Al-oxihydroxide fractions. Apatite is the main P bearing fraction in the sediments, and except in one sample, organic-P is considered to be dominantly refractory. Localised, probably detrital, apatite and barite sources are identified directly adjacent to the Sonora coast. The anomalous enrichment of apatite in one sample with uncommonly high concentrations of labile (non-refractory) P suggests a probable authigenic mineralization in the eastern coast of the NGC. The high abundance of Ba in the Midriff Island region may indicate biogenic sources for this element there. Except for three samples from shallow carbonate bays and the deeper Delfín Basin, the sediments in the NGC contain >90% of Al and Ba and >70 % of Fe, Cu, Cr, Co, Zn and La in residual fractions. The chondrite normalised rare-earth element geochemistry is indicative of typical upper continental crust provenance of the sediments from the NGC.

Internal structure of SST features in the central Gulf of California

Abstract Closely spaced XBT and CTD data were used to study the sub-surface structure of features observed in satellite AVHRR sea-surface temperature (SST) images of the Gulf of California (GC), such as fronts, jets and gyres. The lowest SSTs in the GC are found around the midriff islands, and especially over the sills, because of strong mixing from tidal currents and breaking internal waves. This minimum SST area is limited to the south and north by sharp SST fronts, which frequently show convolutions, gyres, and filaments. A vertical section of temperature along the Gulf length shows that about 300 km south of the sills, the isotherms begin to spread out in the vertical, reducing stratification. The thermocline isotherms begin surfacing about 100 km south of the sill, forming the SST minimum area, which has a maximum temperature difference of ∼6 °C with waters to the south and a horizontal SST gradient of ∼0.05 °C km −1 . The evolution and subsurface structure of a cool filament, apparently originated as an instability of the SST front, was intensely sampled. Satellite images show that its head advanced due south at about 0.5 ms −1 , along the edge of a pool of warm surface water about 110 km in diameter. The thermocline below the warm pool was raised at its edge, and some isotherms reached the surface, producing the cool filament. The tilt of the temperature, salinity and density isolines at the edge of the warm pool produced a geostrophic jet, adjacent to the cool filament and just inside the warm pool, with maximum speed ∼0.5 ms −1 and extending down to ∼80 m. The filament lasted about 10 days, its width was ∼30 km and it reached a maximum length of ∼120 km.The volume transport of the jet in the top 100 m was around 0.7 Sv.

Ocean-color variability in the Gulf of California: scales from days to ENSO

Time series of surface chlorophyll a concentration (Csat) and phytoplankton net primary production (NPP) in the Gulf of California were derived using satellite data from OCTS, SeaWiFS, MODIS, AVHRR and the VGPM primary productivity model. The 6-year (1997–2003) time series showed variability at a multitude of scales. The annual cycle was the dominant mode in Csat variability in the entire gulf, except just south of the midriff islands where the semiannual cycle dominated. The semiannual cycle has Csat maxima during the spring and fall transition periods when the general circulation is switching between cyclonic in the summer and anticyclonic in the winter and is less developed, therefore allowing a more efficient tidal mixing. The spring and fall maxima often consisted of multiple peaks of about 10 days. A significant peak at about 1 month was often present in the short-term Csat variability, especially in areas near the midriff islands, suggesting the influence of tidal mixing. The interannual variability was dominated by the 1997–98 El Niño and the following La Niña. During the El Niño period NPP decreased by 30–40% in the southern part of the gulf (by approximately 1 Tg C month−1), but the changes in the central and northern parts were less evident.

MODERN WAYS OF DESIGNING ROADS THROUGH URBAN AREAS

An important part of forming traffic plans is through designing better traffic conducting. The through roads in urban areas are places of great traffic importance and the concentration of traffic can create serious problems. Solving of this problem significantly influences the future position and functions of current through roads in urban road networks as well as creating the possibilities of new traffic and technical organisation. The purpose of the process of the formation of modern and traffic easing on through roads is to reach better safety levels for all road users, improving pedestrian and cyclist conditions, optimising the used traffic spaces, improving the aesthetic standards of the through roads and slowing down the environmental impact of air pollution and traffic noise. For this purpose the new methodology defines a large number of project elements and specifies the possibilities of its use. It should support new ways of thinking in the designing of through roads and traffic easing, because the implementation of modern European trends is necessary in Lithuania. Firstly it is necessary to choose the optimal road speed and maximum speed limits. The suitable speed limit will depend on the traffic volume, on the number of pedestrians and cyclists and on the surroundings characteristics. Traffic easing elements on through roads generally do not cause a decline of capacity, but under specific conditions it can increase them. The use of particular elements and disposals depends on the place, eg where different elements are recommended to be placed before entry into any town/village, on the town/village's entry or in the use of through roads inside a town/village. Among the most used project elements in traffic easing on through roads, belong changes for the better modification of cross-sections and parking lanes, the implementation of middle traffic islands, local bottlenecks of traffic lanes, modification of crossings for pedestrians and the use of small roundabouts and finally under limited conditions and the use of traffic humps.

Some biological parameters of the peacock wrasse, &lt;i&gt;Symphodus (Crenilabrus) tinca&lt;/i&gt; (L. 1758) (Pisces: Labridae) from the middle eastern Adriatic (Croatian coast)

Data on sex ratio, length-weight relationship, age, growth and survival rate were analysed for peacock wrasse, Symphodus (Crenilabrus) tinca L., (total = 1443; males = 848, females = 595) collected in the eastern middle Adriatic island area during the reproductive period (April and May) from 1995 to 1999. The total length of sampled specimens ranged from 8.9 to 42.5 cm and the weight from 7.9 to 764.2 g. The overall sex ratio was 1.43:1 in favour of males. All individuals larger than 28.9 cm were males as an effect of faster growth. The oldest females were 12 and the oldest males 13 years old. The von Bertalanffy growth formula was estimated for females ( L ∞ = 28.14; k = 0.294; t 0 = - 0.775) and males ( L ∞ = 42.24; k = 0.214; t 0 = - 0.628). The slopes ( b values) of total length - weight regressions indicated allometric growth for males ( b = 2.7205) and both sexes ( b = 2.8147) and isometric growth for females ( b = 2.9901). Survival rate of males (S = 0.80) was slightly greater than that for females (0.756).

MODERN WAYS OF DESIGNING ROADS THROUGH URBAN AREAS

An important part of forming traffic plans is through designing better traffic conducting. The through roads in urban areas are places of great traffic importance and the concentration of traffic can create serious problems. Solving of this problem significantly influences the future position and functions of current through roads in urban road networks as well as creating the possibilities of new traffic and technical organisation. The purpose of the process of the formation of modern and traffic easing on through roads is to reach better safety levels for all road users, improving pedestrian and cyclist conditions, optimising the used traffic spaces, improving the aesthetic standards of the through roads and slowing down the environmental impact of air pollution and traffic noise. For this purpose the new methodology defines a large number of project elements and specifies the possibilities of its use. It should support new ways of thinking in the designing of through roads and traffic easing, because the implementation of modern European trends is necessary in Lithuania. Firstly it is necessary to choose the optimal road speed and maximum speed limits. The suitable speed limit will depend on the traffic volume, on the number of pedestrians and cyclists and on the surroundings characteristics. Traffic easing elements on through roads generally do not cause a decline of capacity, but under specific conditions it can increase them. The use of particular elements and disposals depends on the place, eg where different elements are recommended to be placed before entry into any town/village, on the town/village's entry or in the use of through roads inside a town/village. Among the most used project elements in traffic easing on through roads, belong changes for the better modification of cross-sections and parking lanes, the implementation of middle traffic islands, local bottlenecks of traffic lanes, modification of crossings for pedestrians and the use of small roundabouts and finally under limited conditions and the use of traffic humps. First Published Online: 26 Jul 2012

Insights into Egyptian Horus Falcon Imagery by Way of Real Falcons and Horus Falcon Influence in the Aegean in the Middle Bronze Age: Part II

Falcons were a part of everyday life in the Aegean but also appear in Minoan-Mycenaean art in cult capacity as attending a goddess, being the possible ba bird of a deceased person, and in symbolic ornaments of falcon shape with distinct falcon attributes of sharp talons, hooked beaks, and neck curls. These are possibly major signs of Egyptian influence reaching the Cyclades Islands as well as the Aegeanized Egyptian themes of Middle Bronze Age Minoan art. The bird part of Aegean griffins and griffin wings show distinct origins in falcon traits. The triangular hook markings of kestrels’ underwing flight feathers are the basis of the “notched plume” wing pattern of Aegean griffins. The most suggestive presence of the Horus Falcon and the solar disk in the Aegean is the Middle Bronze Age Melos Island pottery bird designs where falcons have large red disk bodies resembling the solar disks of the Egyptian falcon gods.

Recent hydrogeologic study of the Vis island

The Vis Island belongs to the group of the Middle Dalmatian islands. It comprises an area of about 90.2 km2. Morphologically, three belts of highlands and two depressions with karst poljes are significant. The highest point on the island is Hum with 587 m a.s.l. the island’s water supply is organized from the water-supply station “Korita”, situated in the central part of island, in tectonically formed depression. There are two additional captured objects: the well K-l above the Komiža town and the spring “Pizdica”. The most important hydrogeological role on the island have two hydrogeological barriers, one in the Komiža Bay, completely made of impermeable igneous and clastic rocks, and another one, the recently recognized relative barrier in the area of Dračevo, Plisko and Velo polje. Since the island karst aquifer is in permanent dynamic relation with seawater, classical geologic, structural and hydrogeologic investigations have been performed with application of hydrogeochemical methods taking into account the natural Chemical tracer content of groundwater and its variations in different hydrologic and vegetation conditions. Precipitation regime is very unfavorable with regard to the recharging of island’s aquifer, because dry periods are usually very long. During the summer tourist season, when the number of inhabitants and fresh water consumption considerably increase, amounts of island’s groundwater suitable for water supply and irrigation rapidly decrease. Sometimes, insufficient quantity of fresh water on the Vis Island causes restrictions. Concerning the development of tourist potential and the present agricultural activities, summer lack of water is a serious restrictive factor. Some results of the performed hydrogeological study, important as a basis for island’s fresh water potential assessment, will be presented.

CURRENT STATUS OF THE MANX SHEARWATER (PUFFINUS PUFFINUS) COLONY ON MIDDLE LAWN ISLAND, NEWFOUNDLAND

In 2000 and 2001, the only known North American breeding colony of Manx Shearwater (Puffinus puffinus) on Middle Lawn Island, Newfoundland was visited. Breeding was first confirmed in 1977 and by 1981, a minimum of 13 pairs laid eggs. In 2000, a complete assessment of all burrows was undertaken, and only 2 eggs were found; a third female had an egg in her oviduct. Based on female call rates, capture of birds, and offshore observations, the numbers of non-breeding shearwaters around Middle Lawn Island was comparable to the early 1980s, in the low 100s. The growth of a nearby large gull colony, changing marine ecosystems, and a short breeding season in the northwest Atlantic are possible explanations for why this colony has not become better established. Similar conditions could also be keeping the small Northern Fulmar (Fulmaris glacialis) and Common Black-headed Gull (Larus ridibundus) breeding populations in Atlantic Canada from expanding.

Ocean color observations of eddies during the summer in the Gulf of California

Using SeaWiFS ocean color satellite images collected during 1997–2001, a series of eddies have been observed in the Gulf of California. These eddies are not clearly seen in the summertime sea surface temperature images. The surface circulation between the midriff islands and the mouth of the gulf appears to be dominated by this series of eddies that have an alternating sense of rotation. An eddy pair is observed to extend from Cabo Lobos in each of the three years, suggesting that the eddies are topographically locked. The formation mechanism of the eddies remains unknown; however, we suspect the most likely mechanism includes baroclinic instabilities along the coast produced by interactions between coastally trapped waves, and local wind driven currents.