Intertidal Vegetation Research Articles

Phytobenthic Intertidal Community Structure Along an Environmental Pollution Gradient

The intertidal vegetation of the “Abra de Bilbao” (Basque coast, N Spain) was studied following a pollution gradient. Under the effect of pollution, several signs of alteration are detected in the vegetation, which responds by simplifying its structure. Species which require high quality environmental characteristics such as Cystoseira tamariscifolia, Cystoseira baccata, Bifurcaria bifurcata, Gelidium sesquipedale, Gigartina pistillata and Laurencia obtusa disappear, whereas Corallina elongata, Chondria coerulescens, Caulacanthus ustulatus and Gelidium pusillum become dominant in successive steps as pollution increases. In general, large perennial algae are replaced by small turfing algae. In addition, an intensification of the herbivorous activity (mainly limpets) occurs on the soft caespitose vegetation. Species richness and algal abundance suffer a reduction. In the most degraded environmental conditions, vegetation is replaced by filter-feeders (mussels and barnacles), and cyanobacteria proliferate. Pollution also alters the zonation pattern reducing in the number of vegetation belts.

Intertidal habitat loss and wildfowl numbers: applications of a spatial depletion model

1. A spatial depletion model of the responses of grazing wildfowl to the availability of intertidal vegetation at Lindisfarne National Nature reserve, north‐east England, was used to investigate the capacity of the site’s beds of Zostera and other intertidal vegetation to support brent geese Branta bernicla hrota and wigeon Anas penelope. 2. Recent total winter counts of brent geese and wigeon were both only 40% of the maximum that the food supply at the site could theoretically support. Other factors must have been restricting their numbers. Earlier arrival of brent geese at the site could increase the number of brent goose‐days which could be supported, but would have only a slight negative effect on the wigeon‐days. 3. The model was used to examine three conservation issues: encroachment of Spartina anglica, sea level rise and loss of food plants from the whole site (which could result from increased autumn storms or plant disease). Loss from the top of the shore through encroachment by Spartina anglica had the greatest effect on the site’s capacity to sustain geese and wigeon. Loss from the bottom of the shore, as would occur through sea level rise, had less impact. Increased loss of vegetation over the whole site would have an intermediate effect. 4. This work has important implications for the management of the site. Factors such as hunting, that may be restricting current numbers below those that could be supported by the food supply, require urgent investigation. Model predictions indicate that encroachment of Spartina is likely to depress local populations of brent geese and wigeon under current conditions only if it results in the complete loss of Zostera from the top 500 m of the shore.

Ground and airborne radiometry over intertidal surfaces: Waveband selection for cover classification

Airborne remote sensing using a Compact Airborne Spectrographic Imager (CASI) has been used to map intertidal surfaces (vegetated and unvegetated at low tide) on the East Coast of England for the Land-Ocean Interaction Study (LOIS). This paper describes how ground radiometry with a Spectron spectroradiometer has been used to examine spectra for a range of surfaces and to compare different CASI bandsets for discrimination of different classes of intertidal vegetation and sediments. CASI in spatial mode records data in up to 14 programmable wavebands in the visible and near-infrared spectral range. Different CASI bandsets have been devised for different purposes (some within this project with the aid of Spectron data). A range of these bandsets are compared on simulated CASI data derived from Spectron ground radiometry. Principal component analysis and discriminant analysis show that these CASI bandsets are capable of separating spectra from 10 key surfaces, but that the various bandsets differ little in their effectiveness and that precise waveband selection is not critical.

Statistical, connectionist, and fuzzy inference techniques for image classification

A spectral classification comparison was performed using four different classifiers, the parametric maximum likelihood classifier and three nonparametric classifiers: neural networks, fuzzy rules, and fuzzy neural networks. The input image data is a System Pour l'Observation de la Terre (SPOT) satellite image of Otago Harbour near Dunedin, New Zealand. The SPOT image data contains three spectral bands in the green, red, and visible infrared portions of the electromagnetic spectrum. The specific area contains intertidal vegetation species above and below the waterline. Of specific interest is eelgrass (Zostera novazelandica), which is a biotic indicator of environmental health. The mixed covertypes observed in an in situ field survey are difficult to classify because of subjectivity and water's preferential absorption of the visible infrared spectrum. In this analysis, each of the classifiers were applied to the data in two different testing procedures. In the first test procedure, the reference data was divided into training and test by area. Although this is an efficient data handling technique, the classifier is not presented with all of the subtle microclimate variations. In the second test procedure, the same reference areas were amalgamated and randomly sorted into training and test data. The amalgamation and sorting were performed external to the analysis software. For the first testing procedure, the highest testing accuracy was obtained through the use of fuzzy inferences at 89%. In the second testing procedure, the maximum likelihood classifier and the fuzzy neural networks provided the best results. Although the testing accuracy for the maximum likelihood classifier and the fuzzy neural networks were similar, the latter algorithm has additional features, such as rules extraction, explanation, and fine tuning of individual classes.

Habitat linkages: the effect of intertidal saltmarshes and adjacent subtidal habitats on abundance, movement, and growth of an estuarine fish.

In this study we used pinfish (Lagodon rhomboides) in field experiments to examine linkages between intertidal saltmarsh and adjacent subtidal habitats. Pinfish are more than twice as abundant in intertidal marshes adjacent to seagrass beds than in those adjacent to the unvegetated subtidal bottom. Movement of pinfish between the marsh edge and the adjacent subtidal habitat was greater for fish captured in areas with both intertidal and subtidal vegetation than in those with intertidal vegetation and adjacent unvegetated mudflats. This movement provides an important link between habitats, allowing transfer of marsh-derived secondary production to subtidal seagrass beds and vice versa. Pinfish held in enclosures with both intertidal and subtidal vegetation were, on average, approximately 90% heavier than fish held in enclosures with intertidal vegetation and unvegetated subtidal bottom. Because saltmarshes and seagrass beds contribute to the production of living marine resources, active measures are being taken to preserve and restore these habitats. The results from this study have direct application to decisions concerning site selection and optimal spatial proximity of saltmarsh and seagrass habitats in the planning of restoration and mitigation projects. To maximize secondary production and utilization of intertidal marshes, managers may opt to restore and/or preserve marshes adjacent to subtidal seagrass beds.

A Spatial Depletion Model of the Responses of Grazing Wildfowl to the Availability of Intertidal Vegetation

1. This paper describes the development of a spatial depletion model to predict the distribution and abundance of grazing brent geese (Branta bernicla) and wigeon (Anas penelope) in response to changes in the availability of their food on the intertidal mudflats of the Lindisfarne National Nature Reserve, north-east England. 2. The model incorporated the numbers of the two grazers, their feeding rates, the abundance of Zostera noltii, Z. angustifolia and Enteromorpha sp. (the three main plant taxa on which they feed), the non-grazing loss of vegetation and the birds' feeding preferences. 3. It successfully predicted the distribution of both grazers in both years of the study, despite considerable differences in environmental conditions between the two years. 4. The maximum number of brent geese that could be supported was sensitive to changes in the biomass of the food plants, but relatively insensitive to changes in the numbers of wigeon. The maximum wigeon carrying capacity, however, was sensitive to changes in brent goose numbers. 5. Such spatial depletion models could have general applicability in predicting the consequences of systems in which depletion is important, and the possible effects of habitat loss and environmental change.

Environmental controls on benthic foraminiferal and thecamoebian associations in a New Zealand tidal inlet

Census data on benthic foraminiferal and thecamoebian tests in 52 surface sediment samples from Purakanui Inlet, Otago, New Zealand, are analyzed by cluster and correspondence analyses. Faunas are grouped into 10 sample associations with the following characterizing species: A) Trochammina inflata - at or above mean high water level in high salt meadow, salt marsh or grass; B) Jadammina macrescens/Trochammina inflata - at or above mean high-water level on the edge of high salt meadow; C) Trochamminita salsa in sandy soil at around mean high-water spring, possibly influenced by fresh groundwater seepage; D) Pontigulasia compressa/Trochamminita salsa/Difflugia capreolata - at high tide level in the bed of the main freshwater stream flowing into the inlet; E) Haplophragmoides wilberti - in salt marsh and grass at mean high-water level on the edge of the inlet; F) Miliammina fusca - in Sarcocornia muddy low salt meadow and sandy mud flats between mid and high tide levels; G) Elphidium excavatum - over a wide area of tidal sand flats in the upper and middle parts of the inlet; H) Ammonia beccarii/Elphidium excavatum - in three areas of tidal sand flat in association with G, but with slightly lower salinity and nutrients; I) Elphidium excavatum/Haynesina depressula - intertidally and subtidally around the inner end of the entrance channel in the vicinity of the flood tide sand delta; J) Zeaflorilus parri - intertidally and subtidally in the shallow, current swept entrance to the inlet. These correlate closely with the 8 species associations produced by cluster analysis. Canonical correspondence analysis indicates that the following factors in decreasing order of importance are most influential in determining the faunal distribution: tidal exposure, salinity, percentage of mud, proximity of the open sea, organic carbon, phosphate and intertidal vegetation type.

Does intertidal vegetation indicate specific soil and hydrologic conditions

Six distinct plant zones were identified within a mesohaline tidal marsh in the Cape Fear Estuary, North Carolina. USA. All six vegetative zones were found within an 18-cm portion of the 1.35-m tidal range. Aerial photographs show that these six zones have existed within the marsh for the past 20 years. A monotypicJuncus roemerianus stand occupied soils with the highest salinity porewater (17 ppt), while stands dominated (>90%) by eitherScirpus robustus orTypha angustifolia were found associated with the least saline soil water (7 ppt) in areas of the marsh least flooded by tidal waters.Spartina cynosuroides dominated areas of the marsh at lowest elevations. In general, Eh was highest in theJuncus zone and lowest in theSpartina alterniflora zone. Four of the six vegetative zones represented distinct physical and chemical environments and could be statistically separated via canonical discriminate analyses. We suggest that established vegetation may be an accurate analog for specific hydrogeomorphic conditions.

Marine plants of the Arabian Gulf

The marine plants, which are the primary producers in the Arabian Gulf, include the macroalgae, phytoplankton, mangroves, sea grass beds, and intertidal vegetation. The study of the primary producers of the Arabian Gulf is essential to understand the impact of oil pollution on the marine environment. A limited number of such studies is scattered in various publications. An attempt is made here to provide details on the published information on the primary producers of the Arabian Gulf. A total of 1485 species of these primary producers are reported to exist in this region. Information on the important basic oceanographic features of the Arabian Gulf that influence species diversity, standing stock, and seasonal, and spatial variations are also provided. The effects of oil pollution from spills in the Arabian Gulf from the start of large-scale commercial extraction 60 y ago are also discussed.

Habitat switching by dark-bellied brent geese Branta b. bernicla (L.) in relation to food depletion.

Seasonal changes in the distribution and feeding behaviour of dark-bellied brent geese Branta b. bernicla (L.) and the biomass of their food plants were studied in three successive winters on the Norfolk coast. The data was used, in conjunction with published information, to show how depletion, productivity and mortality of food plants drive the pattern of habitat switching in this species. It is then possible to explain the habitat shifts observed over the last 35 years and predict future changes. On arrival, geese fed first on algal beds and then on salt marsh, grass and arable fields before returning to feed entirely on the salt marsh in spring. The biomass of green algae, and subsequently the salt marsh vegetation, declined during the autumn and this could be attributed to depletion through goose grazing and natural mortality. As depletion occurred the geese fed more intensively, for a greater percentage of time and with an increasing pace rate, the net result, however, was a declining intake rate (as measured by defaecation rate). The algal biomass at which the geese switched from the algal beds to salt marsh was consistent between years, with heavy storm-induced loss of algae in one year resulting in an earlier switch. That the timing of habitat switches may be explained by depletion of food plants was further supported by historical data: the number of brent geese wintering at the site has increased dramatically over the last 30-35 years and the time of switching from algal beds to salt marsh and from salt marsh to salt marsh and fields has become progressively earlier, as expected from the increased depletion. The expected further increase in brent goose numbers will increase the rate of depletion of intertidal vegetation so that the switches between habitats will be more rapid and the geese will move inland earlier and remain inland longer. The expected increase in the brent goose population will thus result in a disproportionate increase in the levels of conflict between brent geese and agriculture.

Sediment physico-chemistry associated with natural marsh development on a storm-deposited sand flat

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 120:271-283 (1995) - doi:10.3354/meps120271 Sediment physico-chemistry associated with natural marsh development on a storm-deposited sand flat Osgood, D. T., Santos, M. C. F. V., Zieman, J. C. Intertidal sediment physico-chemistry was compared at 2 naturally developing barrier island marshes in Virginia, USA. One site was located on the intertidal portion of a sand flat, deposited during a coastal storm in October 1991. The other site was an undisturbed, fringing marsh aged at 14 to 16 yr. Three sampling stations were established at equivalent elevations at both sites. At the marsh site, these sampling stations represented tall and short forms of Spartina alterniflora (low and intermediate elevation stations) and a high marsh zone of mostly Spartina patens (high elevation station). At both sites, sediment across the intertidal zone was characterized by <1.5% organic matter and >90% sand. Relative to the marsh site, the sand flat site had significantly higher pore water salinity and redox potential at the upper elevation stations, higher pH at all stations, and lower hydrogen sulfide at the 2 lower elevation stations. Organically bound nutrients generally were higher in the root zone of the marsh site, but inorganic nutrients were an order of magnitude higher at the low elevation station of the sand flat compared to all stations at the marsh site. The higher concentration of nutrients at the sand flat site may arise from a nutrient-rich mud flat buried during the storm event. This high concentration of nutrients could serve as an external nutrient source to the root zone of the developing marsh and may also lead to a net export of inorganic nutrients to the flooding tidal water. A predictable zonation of intertidal vegetation on the sand flat should exist given the present patterns in sediment physico-chemistry. Based on nutrient standing stocks, the most favorable growing conditions for S. alterniflora exist at the low elevation station of the sand flat, where the tall form of this species is expected to dominate. The short form of S. alterniflora is expected to colonize the intermediate elevation station. A mixed community of species (S. patens, Distichlis spicata) probably will develop at the high elevation station, where the sediment is most oxidized. Vegetation zonation at the marsh site was not readily explained by patterns in sediment physico-chemistry measured in this study. Current research by the authors indicates that nutrient dynamics, controlled by subsurface hydrology, dictates nutrient supply at the marsh site and leads to a higher exposure to nutrients in the root zone of the tall form of S. alterniflora. The present study represents one of few involving measurements of sediment physico-chemistry in naturally developing marshes during the initial stages of development. Salt marsh . Succession . Nutrients . Barrier islands Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 120. Publication date: April 20, 1995 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1995 Inter-Research.

Influence of natural fluctuations in seagrass cover on commercial prawn nursery grounds in a subtropical estuary

Juvenile prawns were captured with a beam trawl from two intertidal seagrass sites (one sparsely and one densely vegetated) in Tin Can Bay, a subtropical estuary in south-eastern Queensland. The abundance and recruitment patterns of two commercial prawn species (Penaeus plebejus and Metapenaeus bennettae) were investigated. P. plebejus was the dominant species at both the sparse and dense seagrass sites. Die-back of the above-ground vegetation in the sparsely vegetated site coincided with a significant increase in the abundance of both P. plebejus and M. bennettae at this site. Natural loss of intertidal vegetation may cause an immediate reduction in the total fisheries value of an area because of fewer herbivorous commercial fish entering the area. In the longer term, this reduction in the fisheries value of the area may be compensated by an increase in value as a nursery ground for juvenile P. plebejus, thereby providing the potential for higher adult P. plebejus recruitment to local commercial fisheries and maintaining the overall value of the area.

Depth as a factor in abundance and size of juvenile penaeid shrimps in the absence of estuaries and marshes

Triweekly trawling around low tide during daylight at 1, 2, 3, and 4 m depths along north Kuwait Bay's extensive intertidal mudflats from 1 April 1985 through 9 December 1986 showed the catchability ofMetapenaeus affinis (H. Milne-Edwards, 1837),M. stebbingi Nobili, 1904,Parapenaeopsis stylifera (H. Milne-Edwards, 1837), andPenaeus semisulcatus De Haan, 1844 differed significantly with depth and season. All species were significantly more catchable in 1 and 2 m depths than in 3 and 4 m depths.M. affinis showed the clearest and most consistent relationship with depth: catchability in 1 m depths was significantly greater than that in 2 m depths (24.9 vs 5.4 per 5-min tow), and catchability in 1 and 2 m depths was significantly greater than that in 3 and 4 m depths (15.2 vs 1.4 per 5-min tow).M. affinis also showed the clearest relationship of increasing size with depth. Shrimp captured in 1 m depths were significantly smaller (~ 14 mm carapace length, CL) than those captured in 2 m depths in the spring (~23 mm CL) and summer (~ 18 mm CL). In the absence of low-salinity waters and intertidal vegetation, it is believed that the edge of the advancing and receding tide over the mudflats, i.e. the shallowest waters, provides juvenile shrimp, particularlyM. affinis, protection from predation.

Size-specific concentrations of phlorotannins (anti-herbivore compounds) in three species of Fucus

Using the Folin-Denis assay, we demonstrated significant (p 0.05) in phlorotannin concentrations among size-classes. Therefore, concentrations of anti-herbivore con~pounds cannot explain different effects of grazers on large and small individuals of F. spiralis. The existence of size-related escapes from herbivory in fucoids is central to the concept of intertidal vegetation structure proposed by Lubchenco (1980). According to this concept, the maintenance of a fucoid vegetation depends on the grazing activities of intertidal herbivores. These grazers are thought to remove competitively dominant ephemeral algae leaving grazer-resistant fucoids to flourish. However, grazer-resistance in Fucus vesiculosus is restricted to larger individuals of more than 3 cm length (Lubchenco 1980). Small specimens were soon eliminated by grazing activities of Littorina littorea, a large periwinkle. In order for a fucoid vegetation to develop, F, vesiculosus must pass through a grazing bottleneck a period of greatest susceptibility when plants are small. In contrast to the results obtained by Lubchenco (1980), Chapman (1989) showed that Fucus spiralis adults were susceptible to grazing by herbivores at natural densities. However, small F. spiralis abundance was not significantly affected by grazing. Geiselman (1980) reported unpublished work by 0. J. McConnell which showed that small ( 10 cm total length) plants, 0.5 g mid-thallus portions, including wing and midrib, were excised with a razor blade and ground in liquid nitrogen. In all cases w e recorded the lengths of individuals used in the analysis. Phlorotannins were extracted in re-distilled acetone from the ground powders. The extracts were evaporated under slight vacuum and the phlorotannins were then re-dissolved in distilled water. After centnfugation, the concentrations of phlorotannins in the supernatant were measured using the Folin-Denis colorimetric procedure (Ragan & Jensen 1977). Purified high 104 Mar Ecol. Prog. Ser. 65: 103-104, 1990 molecular welght polyphenol from F. vesiculosus was used as the reference compound. Concentrations of phlorotannins in the 2 size categories of each Fucus species are shown in Table 1. In F. vesiculosus there were large significant differences in concentrations among large and small plants Table 1 . Fucus spp. Mean -fSD (n = 10 in all cases) concentrat~ons (% of dry weight) of phlorotannins in large and small specimens of 3 species. Lengths of plants (mean + SD) included in the analysis are also given. p-values refer to t-tests for signficant differences among large and small plants within species (see text for details) Species Length Phlorotannin p-value

Habitats of Culicoides spp. in an intertidal zone of southeast Queensland, Australia

The distribution of immature Culicoides Latreille (Diptera: Ceratopogonidae) in the intertidal zone was investigated at Redland Bay near Brisbane, southeast Queensland. The aims of this study were to determine the distribution of Culicoides immatures and to identify environmental factors influencing these distributions. Light trapping of adult midges indicated that C.subimmaculatus Lee & Reye, C.marmoratus (Skuse), C.longior Hagan & Reye, C.henryi Lee & Reye, C.cordiger Macfie, may have been breeding in the study site. Soil sampling on six transects traversing mangrove and salt-marsh revealed the breeding habitats from which immature stages of the first four species were obtained. The elevation, vegetation and soils of positive sites were recorded and analysed for each species of Culicoides. The distribution of intertidal vegetation (mangroves and salt-marsh plants) was compared to MacNae's (1966) system of mangrove zonation for eastern Australia. The distribution of immature Culicoides did not correspond with mangrove zones, but was related to the presence or absence of intertidal vegetation. C.subimmaculatus was closely associated with a particular substrate and the presence of burrowing crabs.

Mortality of Young Brown Shrimp Penaeus aztecus in Estuarine Nurseries

We estimated actual 2-week mortalities of postlarval and juvenile brown shrimp in a Galveston Bay salt marsh by comparing densities of cohorts throughout the spring. Mortalities ranged between 33% and 61% in 1982 and 23% and 39% in 1987. Brown shrimp mortality in predator-exclusion cages during 1987 was less than 3%. These data and published information on food requirements, diseases, and physical tolerances suggest that predation is usually the major direct cause of brown shrimp mortality in estuarine nurseries of the northern Gulf of Mexico. Southern flounder Paralichthvs lethostigina was the dominant fish predator on brown shrimp during the spring, and appeared to be responsible for a large portion of brown shrimp mortality. In laboratory experiments, the presence of smooth corcigrass Spartina alterniflora reduced predation rates of southern flounder and some of the other fish predators examined. Predation rates in general increased in proportion to increased prey densities. Thus, low water levels in the marsh, which reduce access by brown shrimp to intertidal vegetation and increase their densities on nonvegetated bottom, probably result in increased brown shrimp mortality. Mortality and growth may also interact, and predation pressure should be reduced as brown shrimp grow and exceed optimal prey size. Indeed, mortality in the marsh appeared to decline as brown shrimp size increased.

MARINE VEGETATION OF THE MUSERI AND ENTEDEBIR ISLANDS (DAHLAK ARCHIPELAGO, RED SEA)

The intertidal and shallow subtidal marine vegetation of two uninhabited islands in the Dahlak Archipelago, southern Red Sea, is described. The vegetation of these habitats is representative of the entire Archipelago, except for its seaward periphery. Under the highly sheltered conditions prevailing in most of this area, life in the intertidal and in the shallows is rather depauperated, the upper intertidal levels being mostly affected. On the rocky shores, the rarity of periwinkles is the most striking feature at these levels; a little lower down, barnacle belts are completely absent. Species diversity is rather low in the algal communities of the lower intertidal and the upper subtidal. Sciaphilic habitats at these levels harbor a more diverse vegetation, in which a number of species not previously reported from the Red Sea have been encountered. Mangal stands occur in the more sheltered sites. Avicennia marina belts are present in all mangal stands, Rhizophora mucronata belts occur in the highly sheltered sites on the leeward side of the Museri Island, while a single small stand of Ceriops tagal has been observed in a protected depression on the adjacent Desta Island. Bostrychietum, considered for a long time to be nonexistent in the Red Sea, has been found on A. marina aerial roots from an extremely sheltered location in the Melita Bay, Gulf of Zula, on the Ethiopian mainland coast. Caulerpetum serrulatae covers clayey bottoms in ca. 100 m deep troughs between the islands. It is exclusively composed of the low-light ecophene of Caulerpa serrulata , which differs from the normal, high-light form in bearing flat, ribbon-shaped assimilators.

Field and laboratory observations of spawning periodicity and behavior of a northern population of the Atlantic silverside, Menidia menidia (Pisces: Atherinidae)

The spawning periodicity and mating behavior of a northern population of the Atlantic silverside, Menidia menidia, was studied both in the field (Salem Harbor, Massachusetts) and in laboratory experiments. Spawning in the field coincided with new and full moons. Under conditions of unlimited food availability in artificial outdoor pools that received natural celestial illumination or in indoor aquaria receiving no evening illumination, spawning occurred every 1–3 days rather than fortnightly. These results suggest that tidal influences are a primary factor that synchronizes spawning in M. menidia. Published reports of diel time of spawning in both marine and freshwater species of Menidia indicate a generic tendency to spawn during mid-morning. This pattern coupled with high tides that cover suitable spawning substrates during mid-morning only at fortnightly intervals could account for the semilunar spawning cycle in marine populations of Menidia. Although general characteristics of the reproductive ecology of M. menidia in Massachusetts were similar to a thoroughly studied population in South Carolina, several differences were evident. The breeding season was shorter in Massachusetts (late; April–June), and occurred over a much lower range of temperatures (9–21°C). Intensity and frequency of spawning was correlated with the height of high tide. Eggs were deposited only on mats of intertidal, filamentous algae rather than on roots or stems of Spartina alterniflora or other intertidal vegetation. Promiscuous spawning occurred in small, highly male-dominated groups of fish, primarily after the tide had begun to recede, and often at the water's edge. No predation on spawning adults was observed but the mummichog, Fundulus heteroclitus, fed daily on developing embryos during high tide.

Remote sensing of salt marsh vegetation in the first four proposed Thematic Mapper bands

Abstract The potential for using data collected in the first four bands of the proposed thematic mapper for monitoring intertidal salt marsh vegetation is assessed, using ground spectral data collected with a portable multiband radiometer. Results from a field study in Chichester Harbour, Southern England, show that certain species can be separated using transformations of these data. The estimation of above ground biomass from ground spectral data was not possible for Spartina × townsendii agg., due to the combined effects of mixtures of different substrate types and mixtures of live and dead vegetation within the field of view of the radiometer. However, biomass estimation was possible for both Zostera marina L. and Fucus vesiculosus L. The relationships between biomass and bidirectional reflectance for these species followed a similar pattern, despite Fucus vesiculosus having carotenoids rather than chlorophylls as the dominant leaf pigments.

Late Pleistocene-Holocene Sedimentary Infilling and Faunal Change in a Southern California Coastal Lagoon: ABSTRACT

Goleta Slough (Santa Barbara County, California) is typical of several small estuaries and lagoons located along the semiarid southern California coast. The slough presently consists of dendritic, shallow subtidal channels surrounded by intertidal salt-marsh vegetation (mostly Salicornia virginica). It is the last remaining remnant of a large marine embayment that spread into the Goleta Valley basin as sea level rose toward the close of the last glacial period. Stratigraphic data from numerous Goleta Valley water wells indicate that the late Pleistocene embayment End_Page 445------------------------------ was filled by peripheral fluvial sands which wedge out into marine silts and clays closer to the slough's ocean entrance. Sequential air photographs (1928 to present) reveal alluvial fans advancing into the slough from the adjacent Santa Ynez Mountains during the late stages of infilling. Living and relic foraminiferal faunas suggest that these fans reduced an open, well-flushed coastal lagoon to a system of narrow subtidal channels leading from a restricted ocean inlet, frequently closed by longshore sedimentation. Five paleoenvironments associated with lagoon and salt-marsh settings were recognized in shallow cores collected from the slough: (1) subtidal ponds and channels, (2) intertidal flat, (3) intertidal salt marsh, (4) marsh creeks, and (5) alluvial fans. The subtidal lagoon sediments contain a diverse stenohaline (fossil) foraminiferal assemblage that has been replaced in the present slough interior by a single living euryhaline species (Ammonia becarri). Open coast foraminifera are presently found only near the slough's ocean entrance, where conditions approximate a lagoonal environment. The occurrence of marsh sediments in cores collected beyond the present slough boundary indicates a reduction in the extent of the fringing salt marsh. The present marsh vegetation lacks the zonation ty ical of areas subject to regular tidal flooding. These faunal and floral changes indicate that a steady decline in marine influence has accompanied infilling and closure of the Goleta Slough. End_of_Article - Last_Page 446------------