Inland Bays Research Articles

Dependence of Caribbean reef fishes on mangroves and seagrass beds as nursery habitats: a comparison of fish faunas between bays with and without mangroves/seagrass beds

Mangroves and seagrass beds are considered important nursery habitats for coral reef fish species in the Caribbean, but it is not known to what degree the fish depend on these habitats. The fish fauna of 11 different inland bays of the Caribbean island of Curacao were compared; the bays contain 4 different habitat types: seagrass beds in bays containing mangroves, seagrass beds in bays lacking mangroves, mud flats in bays containing mangroves and seagrass beds, and mud flats in bays completely lacking mangroves and seagrass beds. Principal component analysis showed a high similarity of fish fauna among bays belonging to each of the 4 habitat types, despite some dif- ferences in habitat variables and human influence between bays. Juveniles of nursery species—fish species using mangroves and seagrass beds as juvenile nurseries before taking up residence on reefs—showed highest abundance and species richness on the seagrass beds, and on the mud flats near mangroves and seagrass beds, but were almost absent from bays containing only mud flats. The high abundance and species richness on the mud flats near nursery habitats can be explained by fishes migrating from the adjacent mangroves/seagrass beds to the mud flats. Seagrass beds near to mangroves showed a higher richness of nursery species than did seagrass beds alone, suggesting an interaction with the mangroves resulting in an enhancement of species richness. Comparison of fish densities from the 4 different habitat types indicates that for the nursery species the degree of depen- dence on a combination of mangroves and seagrass beds as nurseries for juvenile fish is high for Ocyurus chrysurus and Scarus iserti, the dependence on seagrass beds is high for Haemulon parrai, H. sciurus, Lutjanus apodus, L. griseus, Sparisoma chrysopterum and Sphyraena barracuda, and the dependence on mud flats near mangroves/seagrass beds is high for L. analis. The dependence on mangroves and/or seagrass beds is low for Chaetodon capistratus, Gerres cinereus, H. flavolineatum and L. mahogoni, which can also use alternative nursery habitats.

Importance of shallow-water biotopes of a Caribbean bay for juvenile coral reef fishes: patterns in biotope association, community structure and spatial distribution

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 202:175-192 (2000) - doi:10.3354/meps202175 Importance of shallow-water biotopes of a Caribbean bay for juvenile coral reef fishes: patterns in biotope association, community structure and spatial distribution I. Nagelkerken1,2, M. Dorenbosch2, W. C. E. P. Verberk2, E. Cocheret de la Morinière2, G. van der Velde2,* 1Carmabi Foundation, PO Box 2090, Piscaderabaai z/n, Curaçao, Netherlands Antilles 2Laboratory of Aquatic Ecology, Aquatic Animal Ecology Section, University of Nijmegen, Toernooiveld 1, 6525 ED Nijmegen, The Netherlands *Corresponding author. E-mail: gerardv@sci.kun.nl ABSTRACT: Fish community structure of a non-estuarine inland bay on the Caribbean island of Curaçao was determined in the mangroves, seagrass beds, algal beds, channel, fossil reef boulders, notches in fossil reef rock, and on the adjacent coral reef, using visual censuses in belt transects. Fish communities varied among biotopes, but some overlap was present. Fish density and species richness were highest at the boulders and on the coral reef, and extremely low on the algal beds, whereas the total number of individuals calculated for the entire bay was highest on the seagrass beds. Differences in fish densities between biotopes were related to differences in structural complexity and amount of shelter. Fishes in the bay largely consisted of 17 (mainly commercially important) reef fish species, which used the bay biotopes only as a nursery during the juvenile part of their life cycle. Small juveniles of these species were most often found in the mangroves, whereas at intermediate sizes some were found in the channel. Large individuals and adults were found on the reef, and densities of several of these species were higher on the reef near the bay than on reefs located farther down-current. Fishes which spent their entire life cycles in either the bay or on the coral reef were also found, and the latter group showed a strong decrease in abundance with increasing distance into the bay. The density distribution of individual fish species was not homogeneous within the bay. In the mangroves and seagrass beds, spatial distribution of fishes was correlated with distance to the mouth of the bay, water transparency, amount of shelter, and the structural complexity of the biotope. Juveniles of 3 reef species showed an increase in size on the seagrass beds with distance from the mouth into the bay, whereas 1 bay species showed a decrease in size with this distance. KEY WORDS: Mangroves · Seagrass beds · Coral reef fish · Nursery · Habitat association · Community structure · Habitat complexity Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 202. Online publication date: August 28, 2000 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2000 Inter-Research.

Spawning rhythms of common snook in Florida

Common snook Centropomus undecimaliswere sampled monthly from the Jupiter–Lake Worth area of Florida's Atlantic coast during 1989 and 1991 (1452 fish) and from Tampa Bay on Florida's Gulf of Mexico coast during 1988 and 1989 (2090 fish). Group‐synchronous oocyte development was demonstrated. Ovarian maturation began during March or April on both coasts. Spawning was first detected histologically in April during 1989 and 1991 on the Atlantic coast and during May in 1988 and in April in 1989 on the Gulf coast. In each year, spawning ended during October on the Atlantic coast and during September on the Gulf coast. Ovarian histological evidence suggested that individual females may spawn every 1·1–2·5 days between 1400 and about 2000 hours. Final oocyte maturation occurred independently of either tidal cycle or lunar phase, and some common snook were observed in prespawning or spawning condition on every day sampled. Spawning occurred in or near major inlets to the Atlantic Ocean and the Gulf of Mexico, in secondary passes to larger inland bays and bayous, and around nearshore islands.

A quantitative study of the seagrass and algal meadows of the Spaanse Water, Curaçao, the Netherlands Antilles

The Spaanse Water is a relatively turbid, 3.19 km 2 inland bay of virtually oceanic salinities and contains the largest seagrass, algal and mangrove areas of the Curaçao Underwater Park. During 1989 and 1990, a quantitative community assessment of the larger attached flora and fauna of the seagrass and algal meadows of the bay was conducted at 151 6 m 2 stations using a quadrat sampling technique. A total of 13 different assemblages were distinguished. Shallow assemblages were dominated by Thalassia testudinum and Halimeda opuntia. As depth increased and light levels decreased, Thalassia gave way to increased coverages of especially H. opuntia, H. incrassata, Cladophora sp. and Caulerpa verticillata. In areas with significant availability of hard substrate an assemblage characterised (though not dominated) by corals was found at depths of 0–2 m, while sponges were concentrated at depths of about 4 m. The richest assemblages were found in shallow areas with high light levels and where a mix of both hard and soft substrate occurred. Assemblages with the lowest species richness were typically associated with low light intensities, soupy muds or homogeneous sandy sediments of high grain size.

Climate and kiwifruit cv. ‘Hayward’ 2. Regions in New Zealand suited for production

Abstract Matching crops to climate is an important activity for planning production. Three important climatic factors were identified as being important determinants of kiwifruit (Actinidia deliciosa ’Hayward’ (A. Chev) C.F. Liang et A.R. Ferguson) distribution: winter chilling; growing season thermal time; and annual rainfall. Indices for each of these factors were developed to enable mapping of the most suitable areas for kiwifruit production. These were May‐July temperatures of 11°C or less as the optimal winter chilling requirement, a thermal time accumulation of 1100 degree‐days above 10°C from October to April, and an annual rainfall of 1250 mm or more. Apart from Northland, all the traditional areas of kiwifruit production have a suitable climate. However, there are substantial areas of inland Bay of Plenty to Rotorua, the Waikato, north Taranaki, and northern Hawke's Bay where the climatic requirements are also satisfied. A high frequency of extreme winds may be an additional limiting factor in some of these regions, such as Taranaki. The total area of suitability is enlarged if irrigation is available, particularly in the southern North Island and central Marlborough. Within this climatic range the estimated dates for the average end of dormancy and 50% flowering are spread over 4 weeks, and estimated budburst dates over 11 days. Although use of average climate data to describe kiwifruit distribution provides a valuable first‐order assessment, it would be desirable to incorporate analyses of climate variability in future studies of this kind.

Distribution of Marbled Murrelets along the Oregon Coast in 1992

Strip transects from boat and light aircraft were used to quantify the distribution and abundance of marbled murrelets (Brachyramphus marmoratus) along the length of the Oregon coast. Murrelets were abundant in central Oregon between Newport and Coos Bay, with observed densities averaging 78 birds/10-km by 100-m strip (N = 90, SE = 5.9). Murrelets were relatively scarce north of Lincoln City (x = 6.8 birds/10-km by 100-m strip, N = 32, SE = 1.2), with small concentrations near coastal State Parks that contained old-growth forest stands. Murrelet abundance was variable from Coos Bay to the California border (x = 28.4, N = 22, SE = 5.9). Highest densities occurred in a narrow band and decreased sharply at > 1 km from shore. There was evidence of a northward and offshore shift of the population late in July, which may have been related to a prey shift from surf smelt (Hypomesus sp.) to Pacific sandlance (Ammodytes hexapterus) or to post-breeding dispersal. The abundance of marbled murrelets seen during this study suggests that the population in Oregon is higher than previously estimated. Marbled murrelets (Brachyramphus marmoratus) are small diving seabirds that have the unique adaptation of flying inland to nest in large trees along the west coast of North America (Marshall 1988, Hamer and Nelson 1995a). At sea, marbled murrelets occupy inland passages, bays, and near-shore waters of the open coast; they rarely are seen over 3 km from shore (Sealy 1975b, Carter 1984, Carter and Sealy 1990, Rodway et al. 1992, Ralph and Miller 1995). Because detection and quantification of marbled murrelets is very difficult in their forest nesting habitat, surveys of the birds at sea is presently the most effective and accurate means of assessing population size and distribution. The need for information on abundance and distribution of marbled murrelets was accentuated by the species' listing as federally threatened in October 1992 (U.S. Fish and Wildlife Service 1992). All of the 3 prior at-sea studies of marbled murrelets in Oregon (summarized in Nelson et al. 1992) were made along short sections of the coastline, and each study used different methods and observation vessels, making comparison difficult. Besides those at-sea counts, numerous observations from shore of marbled murrelets in Oregon have been made over the years (Nelson et al. 1992, Nelson and Hardin 1993). To this point, information on population size and distribution in Oregon has been derived from inland and shore-based observations and the work of Varoujean and Williams (1995). Based on vessel and aerial transects, preliminary results of the first state-wide surveys of marbled murrelets along the Oregon coast are presented here. This ongoing research is directed towards establishing a population estimate and monitoring protocol for the species in Oregon.

The Subtidal Lagrangian Current in Delaware's Inland Bays Under Low Wind Conditions

A series of field surveys were conducted in Delaware's inland bays to investigate the subtidal current in a Lagrangian framework. Drifters tracked by the LORAN-C and satellite (ARGOS) positioning techniques were released in January and April of 1992. The LORAN-C position data were first locally corrected, and then inter-compared with the concurrent ARGOS data. Subtidal currents were then examined based on LORAN-C position data obtained under low wind conditions. Current velocities, calculated from a central finite-difference algorithm, were generally less than 3·0 Cm s -1 in the bays, although larger currents (5·5 cm s -1) were observed in the vicinity of the Indian River Inlet. Correlation between the subtidal current and wind was also systematically examined. In January, subtidal current and wind were favourably correlated with a complex correlation coefficient of 0·78 and an average veering of about 3°. In April, however, a poor correlation was found between the current and wind vector time series.

Low‐frequency variability in Delaware's inland bays

The low‐frequency variability in Delaware's inland bays is examined based on observational data derived from a combination of tide gauges, moored current meters, and free‐floating Woodhead drifters. The currents and surface elevations in the bays exhibit considerable fluctuations at subtidal timescales of 2–7 days. These subtidal fluctuations are forced primarily by the remote atmospheric effects through the imposition of coastal sea level setup or setdown at the entrance of the bays. To first order, the current and sea level fluctuations in the interior of the system respond to coastal forcing in a pumping mode fashion. With a coastal setup (or setdown), water is pumped into (or out of) the system from all open boundaries. This pumping mode response produces vigorous subtidal current fluctuations (of the order of 25 cm/s) in the Indian River Inlet. In addition to the subtidal fluctuations, the data also indicate the presence of significant residual currents of the order of 10 cm/s in the Indian River Inlet. The residual currents have a pattern of surface outflow and bottom inflow that is consistent with the density‐induced gravitational circulation.

Delaware's inland bays: A case study

Abstract A management plan has been developed for the Inland Bays which is a major coastal estuary. Eutrophication and closure of shellfish areas are two major water quality problems in the Inland Bays. The largest source of nutrients entering the bays is from nonpoint sources. Agriculture is the largest contributor of nitrogen and phosphorus. Best Management practices (BMP's) such as manure nutrient analysis, calibration of manure spreaders, timing of application and applying only enough nitrogen to be removed by the crop are being emphasized to make more efficient use of nutrients in poultry manure and commercial fertilizer. Erosion and runoff control BMP's would have little effect on reducing nitrogen and phosphorus loads to the bays because of the porous soils.

Distribution of Oligotrophic and Eutrophic Bacteria in Fish Culturing Inland Bays.

The distribution of oligotrophic and eutrophic bacteria in fish culturing inland bays was in-vestigated by the most probable number (MPN) method using both poor (ca. 0.3mgC/l) and rich (ca. 300 mgC/l) culture media. Bacterial growth in the rich media (eutrophic and facultatively oligotrophic bacteria) was detected by turbidity and that in the poor media (obligately and facul-tatively oligotrophic bacteria) by epifluorescence microscopic observation after DAPI (4', 6-di-amidino-2-phenylindole) staining. The total counts of heterotrophic viable bacteria in bottom sediments, seawater and particle fractions (>5μm) were ca 107 cells/g, 103-105 cells/ml, and 102-103 cells/ml, respectively. In seawater samples, oligotrophic bacteria, especially obligate oligotro-phs, were often predominant. While, facultatively oligotrophic bacteria were predominant in the fractionated water samples (>5μm). As particulate organic matters provided nutrient rich microspheres for microorganisms in seawater, non-random distribution of eutrophic and facul-tatively oligotrophic bacteria were observed. Different from the bottom sediments in the open sea, obligate oligotrophs were never detected in the bottom sediments of the fish culturing areas. The occurrence of eutrophic bacteria in bottom sediments of fish farms seems to be mainly due to the heavy load of sedimented organic matter which is derived from left-over feed and fish excreta.

Formation of C 20 isoprenoid thiophenes in modern sediments

Three isomers of C 20 isoprenoid thiophenes were identified in the solvent extracts from diverse modern sediments including brackish water lake and inland bay sediments, that were under highly reducing saline conditions. Based on the field observations and some laboratory experiments, this paper demonstrates that the likely formation reaction of these thiophenes is from chlorophyll-derived phytol and hydrogen sulfide (H 2S) via phytadiene intermediates. The reactions of phytol sealed with H 2S-saturated seawater, lacustrine freshwater and distilled water all produced two of the three thiophene isomers above. The molecular structure of the thiophenes determined by their mass spectra suggested an incorporation of sulfur into the conjugated s- cis diene moiety of phytadienes, which can be formed by dehydration of phytol. An acid dehydration experiment of phytol in aqueous media yielded ffour phytadiene isomers. Subsequent reaction of the phytadiene mixture in the H 2S-saturated seawater gave the same two thiophene isomers. These results provided substantial evidence for a mild reaction to produce the limited number of C 20 isoprenoid thiophene isomers which occur during the very early stages of diagenesis, not only under saline but also under freshwater conditions. In fact, the three C 20 isoprenoid thiophene isomers were identified in the surface sediment of a freshwater lake of low pH owing to the inflow of sulfide-rich hot-spring water (Lake Usori-ko, Japan).

Estudio de la contaminación marina por hidrocarburos en el Litoral Sur Pacífico Colombiano

In this work planted and discussed the results of the disolved/dispersed hidrocarbon analysis on water and accumulated in sedimenta and bival vos, in higher vulneravility zone of Colombian pacific (Pacífico Colombiano). This study is part of the program coordinated of monitoring and vigilance of the pollution in coast areas of Saudeast Pacific of Permanent Soud Pacific Comition, CPPS, (Comisión Permanente del Pacífico Sur). This presented the results obtaineds during september /87, to february /89, period in the Inlet of Tumaco, Gorgona Island and Buenaventura Bay. The disolved/dispersed hidrocarbon concentration are low on the coust, with exception of the registred levels on the Ecopetrol's Buenaventura pier's exceded 10 Ug/1. Sedimenta and bivalvos were contamined by hidrocarbons in the inland bay of Tumaco, Anchicaya's outlet river's and Ecopetrol's Buenaventura pier's. The higher hidrocarbon's concentration total were registred in Buenaventura bay, diminish in the inlet of Tumaco and minors in the around of the Gorgona Island.

Species assemblages and phenotypes of mushroom corals (fungiidae) related to coral reef habitats in the Flores sea

Corals belonging to the family Fungiidae were studied at coral reefs in and around the Flores Sea. Our aims were (1) to obtain a better insight into the factors affecting species richness and (2) to investigate the relations between reef habitats and coral phenotypes. Some fungiid species occurred on almost all reefs, others on very few. Examples are given of coral reefs which are characterized by extreme environmental conditions. Bottom inclination, water turbulence and substratum type appear to be important environmental factors controlling fungiid species composition. Areas with a great variety of reef habitats are usually rich in species, some of which are rare. Three major reef types are recognized in relation to ecomorphological variation: (1) reefs in open sea, (2) sheltered coastal reefs facing open sea and (3) reefs in inland bays. Field observations suggest that growth forms are primarily related to light intensity but also to water turbulence and type of substratum.

地形分類を基礎とした日本と韓国の河成平野の比較研究

We have conducted a comparative research on the fluvial plain between Japan and South Koreabased on geomorphological land classification. There are distinct regional differences in thegeomorphology of Japan and South Korea even though they are adjacent to each other. The fluvialplains in Japan are depositional plains, but in South Korea they are basically erosional plains, eventhough they are thinly covered with sand and gravels. Based on the combination of geomophological elements, the plains of Japan and South Korea areclassified as follows: <Japan> (“On” group =basic form) Fan+Natural Levee (Back Marsh)+Delta.(“Od” group) small fan+small natural levee+Delta no fan+no natural levee+Delta. <Korea> (basic from) Pediment+Pen-pediment+Natural Levee (Back Marsh)+Tide land.(R. Naktong) Pediment+Peri-pediment+Natural Levee (Back Marsh)+Delta+Tide land. The above outlined differnces were formed by the following factors: 1) In Japan, erosion in the mountainious region is pronounced due to the steep topography andbecause of the torrential rainfall. Sand and gravels were supplied to the valley bottom by land collapses and transported to the plainby rivers during the flood season. They were deposited at the boundary between the mountainousregion and plains, and formed fans. In South Korea, a great deal of fine-grained material is produced because of the wide distributionof gneisses and granitic rocks which are easily weathered and by mechanical weathering in themountainous region due to the low temperatures during the winters. The debris which was formed onthe surface of the mountanious regions was washed away by torrential rainfall during the summerseason. The gravels were deposited on the gentle piedmont slopes, especially the lower parts ofpediments which were thinly covered with sand and gravels were formed as peri-pediments. 2) The coefficients of river regimes are large in the rivers of both countries. The ratio in Korea islarger than that of Japan. The longitudinal profile of rivers in Japan is steeper than that of Korea. Due to the above mentioned features of the rivers, a great deal of sand and gravel was transportedin Japan and sand were transported in South Korea, so that natural levees are developed better in South Korea than in Japan. 3) In Japan, the deposition of sand and gravels a t the lowest reaches is remarkable. Because manyrivers pour into inland bays, many big deltas are formed in the lowest reaches. In South Korea, the deposition of sand and gravels in the lowest reaches is difficult partly becausethe rivers pour into the open sea directly, and partly because of the very wide tidal range, for example 8.1m at the lowest reach of the Han River. 4) The differences between the two groups based on the combination of geomorphologicalelements in Japan are related to whether a river has intermontane depressions and gorges in the upperreaches or not: the “On” group has no intermontane depressions or gorges in the upper reaches, whilethe “Od” group has. The differences in the combination of geomorphological elements in Korea are based on naturalconditions at the river mouth.

The response of Delaware's inland bays to ocean forcing

Sea level and current observations made during a 2‐month summer period in Delaware's inland bays are used for the examination of the tidal and subtidal variability in the bays. To first order, the coupled inland bays are found to be forced primarily by coastal sea level fluctuations at both tidal and subtidal frequencies. The observations suggest that the systems behave as low‐pass filters in response to coastal forcing. Overall, tidal variance decreases sharply inside the bays, with the semidiurnal tides suffering significantly higher attenuation than the diurnal tides. The subtidal variability, however, experiences no appreciable attenuation within the bays. The systems are also found to be only weakly nonlinear in nature. A linearized frequency‐dependent pumping mode model is developed, and results indicate that the model adequately describes the first‐order response of the inland bays to coastal sea level forcing.

Tidal and Subtidal Variability in Delaware's Inland Bays

Sea level observations made during a three-month period in late 1984 at four stations in and near Delaware's inland bays are used for the examination of tidal and subtidal variability in the bays. Five tidal Constituents are found to be active in the bays, With M2 being the most important one. The inland bays, with their narrow inlets and shallow depths, behave like low-pass filters for oceanic disturbances propagating into the interior of the bays. Overall, tidal variance decreases sharply inside the bays, with the semidiurnal tides suffering significantly higher attenuation than the diurnal tides. At subtidal frequencies, sea level fluctuations in the interior of the bays are primarily forced by coastal sea level fluctuations generated by atmospheric forcing on the adjacent shelf. Local wind forcing within the bays appears to play only a secondary role in modifying the coastally forced sea level. The active subtidal sea level fluctuations induced by the bay-shelf coupling effect experience no appreciable attenuation within the bays. As a consequence, sea level variance at subtidal frequencies is even greater than that at tidal frequencies in one of the inland bays.

INNOVATIVE DETERMINATION OF NEARSHORE FLOOD FREQUENCY

Reliable estimates of coastal flooding from tides and storm surges are required for making sound engineering decisions regarding the design, operation and maintenance of many coastal projects. A recent investigation of flood frequency along the coast and within the bays of southern Long Island, New York, produced new and optimal approaches to obtain meaningful statistical estimates of flood levels. This paper summarizes various elements of the study and concentrates on the problem of stage-frequency computations in the inland bay areas. Methods for optimizing the number of necessary storm/tide simulations and estimating the accuracy of results are presented.

GEOMORPHIC EVOLUTIONS OF THE ALLUVIAL LOWLANDS IN JAPAN

Alluvial lowlands occupy about 13% of the total area of the Japanese Islands, and widely distribute along the coasts and the lower reaches of the rivers. They have been developed under the influence of environmental changes in the late Quaternary, especially under the eustatic change of sealevel. However, geomorphic evolution of each lowland is quite varied one another. In this report, the author tries to make clear the geomorphic development and regional difference of alluvial lowlands in Japan by means of the reconstruction of paleogeography. On the basis of paleogeographic development, alluvial lowlands in Japan are classified into six developmental series: F, N-S, D, D-S, V and C. The F series lowland is mainly composed of alluvial fan constructed since the Lastglacial age. Examples of this series are the lowlands of the Fuji, the Oi and the Kurobe Rivers. The N-S series takes its own evoultional course as follows: At the stage of the lowest sealevel in the Lastglacial age, the lowland had been composed of narrow alluvial fan or valley bed in the valley cutting the lower reach of the river by the lowering of sealevel. As a result of the transgression, the lower part of the lowland was drowned and changed to the lagoon in the Lateglacial age. During the former half of the Holocene, the lagoon was extended to the inland area, and the lower reaches of the river had changed into the flood plain composed of sandy and silty sediments. The lagoon had been reclaimed by sediments in the latter half of the Holocene. Then the landform of alluvial lowland was characterized by the alluvial fan, the flood plain and the sandy bank from upper to lower reaches of the river. Examples are lowlands of the Sagami and the Tenryu Rivers. The evolutional process of D series-alluvial lowland is as follows : At the stage of the lowest sealevel in the Lattglacial age, the lowland was composed of narrow alluvial fan in the valley developed between river terraces, and they were such landforms as the N-S series. In the Lateglacial age valleys were drowned from their lower reaches. In the former half of the Holocene, river terraces and valleys were filled with alluvial sediments, and the sea was widely invaded towards the upper reaches. Then the remarkable delta was constructed burying the shallow part of this inland bay. In the latter half of the Holocene, the delta has continued to develop seaward and floodplain deposit has also extended to the inland area. We can find good examples for this series in the evolutions of the Tokyo-shitamachi, the Tama River and the Yahagi River lowlands, and the Nobi plain. The D-S series is subdivided into (a) and (b) types. Both series are characterized by lagoon and sand bank in the Holocene. The lagoon had spread out since the Lateglacial age or the early Holocene accompanied with the sealevel rise. The lowland was mainly composed of both floodplain and delta facing on the lagoon, which was gradually reclaimed in the late Holocene and became swampy land. The topography of D-S (a) series lowland in the latest Pleistocene is the same with that of D series. During the Lateglacial age, the landform of D-S (b) series was composed of narrow floodplain and delta. Lowlands, such as the Kushiro, the Tsugaru and the Fukui plains belong to D-S (a) series. The Ishikari and the Kawachi plains can be classified into D-S (b) series. The evolutions of V series such as the Yamada, the Tsurumi and the Ota Rivers are characterized by the drowned valleys which have extended since the early period of their evolutions. The reclamation of drowned valleys had proceeded in the late Holocene. The lowlands of C series had been developed in the valleys during the Lateglacial age. The alluvial lowland was composed of either the narrow alluvial fan or the floodplain and delta at this time. The lowland became facing to the open bay by the sealevel rising in the Holocene.

CHEVRON MAIN PASS BLOCK 41 OIL SPILL: CHEMICAL AND BIOLOGICAL INVESTIGATIONS

ABSTRACT During a three-week period in 1970 an estimated 65,000 barrels of 34° API gravity crude oil were discharged from the Chevron Main Pass Block 41C Platform, 11 miles east of the Mississippi River Delta. Two thousand barrels of chemical dispersants were sprayed on the platform and surrounding water surface. It is estimated that between 25–30% of the oil evaporated during the first 24 hours, 10–20% was recovered from the water surface, less than 1% dissolved, and less than 1% of the oil was identified in sediments within a 5-mile radius of the platform. The remaining oil emulsified and dispersed to undetectable levels, biodegraded, or photooxidized. The highest measured concentrations in water at the platform and at 1 mile were: oil-in-water emulsion, 70 to 1 ppm; dissolved hydrocarbons, 0.2 to 0.001 ppm; dispersant 1–3 to unmeasurable (&amp;lt;0.2ppm). Total extractable organic matter was highest in sediments near the Mississippi River Delta and in the inland bays. Spilled oil, identified in bottom sediments by gas chromatography, showed rapid weathering after 1 week to 1 month and at the end of 1 year was reduced to a few percent of the amount after the spill. Spilled oil was not found in the sediment below 1.5 inches. Over 550 species of benthic organisms were identified in 233 benthic samples. The number of species and number of individuals of benthic organisms showed low values in some samples near the platform. However, seasonal variations, bottom sediment type, and possibly other environmental parameters made it impossible to determine whether these locations had been affected by the spilled oil. There was no correlation of number of species, number of individuals, or other biological parameters with the hydrocarbon content of the sediments for samples from within a 10-mile radius of the platform. This lack of correlation suggests lack of significant effect of oil on benthic organisms. Extensive trawl samples showed no alteration in the annual life cycle of commercially important shrimp. Blue crabs were observed throughout the area, and the number of species of fish collected were comparable to a prior survey.

Ecological Aspects of the Distribution of Reef Corals in the Netherlands Antilles

The vertical and horizontal patterns of the distribution of corals and coral reefs (to a depth of 90 m) are discussed in relation to the environmental factors: geomorphology of the bottom, available substrate, light, turbidity, sedimentation, water movement and temperature. There is a general pattern which is comparable to other well-developed Caribbean reefs. However, as in other areas variations are found, e.g. the depth and growth form of Acropora palmata will depend on the degree of exposure to water movement. There are strong correlations between the environmental variables and the occurrence of coral species and their growth form, the species composition of coral communities and the character of the coral reef. In some cases the relationship is not that obvious. The absence of Agaricia species at certain points along the coast of Aruba and the dominance of Sargassum on the deep bottom at some places along the windward coast of Curaçao is not yet explained. The relative importance of the different factors in an environmental setting is shown by a comparison of reef communities and reef habitats with a coral community of a muddy, shallow inland bay. The community of the bay consists, apart from the hardier coral species, of corals which are characteristic of the deep reef: Scolymia lacera, S. cubensis and Helioseris cucullata. These corals are adapted to sedimentation and low light intensities and are apparently able to withstand a temperature and salinity range much broader than that of their deep reef habitat. The paucity of corals and coral reef development around the islands of the Windward Group (deeper habitat included) can generally be explained by the morphology of the sea floor, the lack of suitable substrate and the effect of hurricanes. The exposed coasts of Saba and St. Eustatius, being virtually unexplored, may have richer coral growth. A new list of species of the Scleractinia of the Leeward and Windward groups, consisting of 57 species, is included.