Intertidal Waters Research Articles

THE LARVAL DEVELOPMENT OF PANOPEUS MARGENTUS(DECAPODA: BRACHYURA: PANOPEIDAE) REARED IN THE LABORATORY

Abstract The panopeid crab Panopeus margentus is known to inhabit intertidal and subtidal temperate waters of the southwestern Atlantic Ocean, from Rio de la Plata to Mar del Plata, Argentina. The complete larval development of this species is described from laboratory-reared material and compared with known larvae of Panopeus, Eurypanopeus, and Hexapanopeus. A preliminary key for the identification of panopeid megalopae from the temperate waters of the southwestern Atlantic is provided.

Temporal and spatial high resolution analysis of nutrient dynamics in the near bottom layer of the Wadden Sea: Methodological aspects and first results

A probe that allows to take water samples in intertidal areas at high spatial resolution in the first metre above the bottom without disturbing the current profile has been developed. Data on dissolved inorganic nutrients were obtained at a temporal resolution of 30 minutes and spatial distances of 2, 4, 8, 16, 32. 64 and 100 cm above the bottom from up to three hours before to up to four hours after high tide. The layer in direct contact with the sediment showed marked concentration changes with tidal state. All compounds analysed exhibited a pronounced minimum at or immediately after current direction change. Depth profiles, on the other hand, did not give such a consistent picture. Individual compounds showed fluxes into and out of the sediment independently of each other and of tidal state. The data obtained suggest that sediment-water interactions play a major role in controlling nutrient concentrations in intertidal waters on short time scales.

LATE QUATERNARY PALEOSEALEVELS AND PALEOENVIRONMENTS INFERRED FROM FORAMINIFERA, NORTHERN SPENCER GULF, SOUTH AUSTRALIA

Spencer Gulf is an elongate marine embayment extending northwards ca. 300 km inland into southern continental Australia to the apex at Port Augusta, with a narrow estuarine extension northwards. Since the post-glacial sealevel maximum, prograding coastal sedimentation has been effective through the trapping and binding actions of seagrasses, mangroves and cyanobacterial mats, and a well-defined zonation of subtidal, intertidal and supratidal sedimentary facies is characteristic of the northern gulf. Mollusks and foraminifera are prolific, especially within seagrass meadows, and their abundant remains, entire and comminuted, form bioclastic carbonate sediments. Distinctive assemblages of foraminifera are associated with the various estuarine and marine environments. The hypersaline estuary north of Port Augusta is characterized by the textulariids Ammobaculites barwonensis and Trochammina inflata, the latter most common where mangroves are present. Two species of Triloculina, T. inflata and T. oblonga are the only common miliolids, while the rotaliids are represented by Ammonia beccarii, Elphidium articulatum and Nonion depressulus. South of Port Augusta, in euryhaline intertidal waters, Trochammina inflata, A. beccarii and E. articulatum are commonly associated. The shallow subtidal Posidonia seagrass meadows support an abundant fauna which is dominated by three species, Nubecularia lucifuga, Peneroplis planatus and Discorbis dimidiatus. These species continue into the deeper waters, ca. 20 m, where they are subordinate to Quinqueloculina lamarckiana, Massilina milletti, Elphidium crispum and E. macelliforme. A vibrocore from 20 m water depth in Northern Spencer Gulf recovered 4 m of late Quaternary fossiliferous sediment. Amino acid racemization (AAR) and radio-carbon ages derived from fossil mollusks revealed four chronostratigraphic packages of sediment: 400–360 cm, penultimate interglacial, oxygen isotope stage 7; 360–240 cm, last interglacial, oxygen isotope substage 5e; 240–180 cm, interstadial, oxygen isotope stage 3; and 180 cm to the top of the core, postglacial, oxygen isotope stage 1. Species of foraminifera within the core are mostly also living in the modern gulf, thus the preserved assemblages permit plausible interpretations of paleoenvironments and paleosealevels. Large numbers of Q. lamarckiana and M. milletti in the substage 5e interval indicate that the last interglacial sealevel in southern Australia was only slightly higher than that of today. N. lucifuga is abundant in the stage 3 sediment, thus paleowaterdepth at the core site was ca. ≤2 m. This evidence further supports interstadial paleosealevels above −30 m, as previously determined for Gulf St Vincent. Basal sediments of the postglacial interval preserve a monospecific assemblage of Miliolinella labiosa which signifies an estuarine setting having many of the characteristics of a saline lake. Maximum Holocene sealevel is signified by the acme of M. milletti at 90 cm. Subsequent local hydroisostatic relative fall of sealevel is shown by changes up-core from 90 cm in both the general foraminiferal record, for example by declining numbers of M. milletti, and also by reduced numbers of E. macelliforme compared with those of E. crispum.

Detailing agents of physical disturbance: wave-induced velocities and accelerations on a rocky shore

Abstract Water motion produced by breaking waves plays a defining role in structuring intertidal communities. However, despite the clear ecological importance of wave action, fine-scale details of the flows generated by breaking waves on rocky shores have not been well-described. This lack of information has hindered the efficacy of mechanistic studies aimed at exploring quantitatively the processes leading to wave-induced damage or mortality of organisms in littoral habitats. In response to these limitations, high-frequency field measurements of intertidal water velocities and accelerations were conducted simultaneously with recordings of inshore wave height at four representative sites in the mid-intertidal zone of a rocky shore. Maximum velocities and accelerations recorded under waves of measured height are presented and placed in the context of simple wave theories. Rates of occurrence of simultaneous velocities and accelerations are computed as a function of wave height, providing a means of linking instantaneous values of drag and lift to concurrent hydrodynamic accelerational forces. These data together provide an improved, high-resolution picture of the nature of flows typical of littoral environments and their relationship to wave height, and as such serve to reemphasize both the severity as well as the stochastic nature of the fluid motions that characterize wave-swept coasts.

Use of intertidal and adjacent mudflats by juvenile penaeid shrimps during 24-h tidal cycles

Trawl tows every 3 h throughout 24-h tidal cycles at 0.6, 1.0 and 2.0 m depths along three transects sampled the extensive intertidal and immediate subtidal mudflats in north Kuwait Bay on 4–5 June and 25–26 June, 1989. Results showed catch rates of Penaeus semisulcatus De Haan, 1844, Metapenaeus affinis (H. Milne Edwards, 1837), Parapenaeopsis stylifera (H. Milne Edwards, 1837), and M. stebbingi Nobili, 1904 to differ significantly with the main effects of diel period, depth, and tide. Interactions differed depending on species. All species were 2–5 times more catchable at night than during day. The shrimp species could be partitioned into two categories: subtidal mudflat specialists included P. semisulcatus, P. stylifera and M. stebbingi, and intertidal mudflat specialists as represented by M. affinis. Common to all subtidal mudflat specialists were increased catch rates with depth and increased catches at low tide. Highest catches of subtidal mudflat specialists usually included combinations of night, 2 m depths, and low tide. In contrast, M. affinis catch rates increased significantly with decreasing depth. Results show that the subtidal mudflat specialists remain in the area of low–low tide throughout the tidal cycle, while the intertidal mudflat specialist, M. affinis, followed the tidal front as it advanced and retreated across the intertidal area. Apparent catchability varied widely depending on timing and location showing the importance of establishing sampling criteria prior to conducting a sampling programme for recruitment indices. The behaviour patterns demonstrated by the species examined here are believed to result from predator avoidance with subtidal mudflat specialists using low tide and the cover of darkness for protection, while M. affinis utilized the shallow intertidal waters on mudflats where shrimp predators were few.

Note on the Trophic Relationships of the Stauromedusa Haliclystus Antarcticus from Subantarctic South Georgia

Stauromedusae are cnidarians that have attracted relatively little ecological study, especially in the southern hemisphere. They are Scyphozoa that develop directly from the scyphistoma, and each consists of a calyx and a more or less distinct aboral peduncle that attaches to the substratum by an adhesive disc. The animals are mobile on the substratum, but have no pelagic phase. The present note originates from observations made on stauromedusae living in intertidal and shallow subtidal waters at Husvik Harbour, South Georgia (54°11′S 38°40′W) in early 1994. The species concerned was identified from Kramp (1961), Carlgren (1930) and Pfeffer (1889) as Haliclystus antarcticus Pfeffer, 1889. This species has attracted little previous study. The most detailed anatomical description was given by Carlgen (1930), while distributional details are given in O'Sullivan (1982) who followed Pfeffer (1889); at present there is no evidence that the species occurs other than at South Georgia.Medusae were found on two substrata. Large animals (~30mm high, inconspicuous dark brown in colour) were found on the underside of boulders at extreme low spring tide level in a bay on the north of Husvik Harbour about 1·2 km from the whaling station and close to Brain Island. Locally they were common, often being close enough to touch one another. Smaller animals (pink-orange in colour; cryptic on the macroalga) were found attached to the brown macroalga Desmarestia menziesii J. Aghardh (Phaeophyceae) collected at low-water spring tide level from Kanin Point on the southern shore of the harbour. Medusae on boulders were briefly emersed on particularly low tides: they collapsed, hanging from the peduncle, when out of water, but did not risk desiccation as their habitat was wet and not exposed to the sun.

Factorial analysis of annual erosion-accretion cycles of tidal flats in the front area of the southern Changjiang river delta

Based on surveyed data from seven coastal sections and the collected data of wind, sea level, tide, nearshore suspended sediment concentration and river flux from adjacent stations, this paper deals with regressive correlation between monthly average flat elevation and monthly average figures of the influential factors. All sections except one which is located within the river mouth showed negative correlation between flat elevation and sea level and between flat elevation and tidal range, with correlation coefficients being −0.53 – −0.91 (−0.77 on the average) in the former condition and −0.56 – −0.97 (−0.80 on the average) under the latter. Each of the sections with available suspended sediment concentration (SSC) data shows a positive correlation between flat elevation and SSC, with correlative coefficients being 0.35 – 0.97 (0.66 on the average). Only two sections (one in the Changjiang River Estuary and the other in the Hangzhou Bay) which are similar to beaches in sediment grain-size and slope gradient showed a negative correlation between flat elevation and onshore wind frequency and between flat elevation and average wind velocity, with correlative coefficients being respectively −0.57 and −0.69 (−0.63 on the average) in the former situation and −0.61 and −0.75 (−0.68 on the average) in the latter. Other sections did not show uniform relationship between flat elevation and wind conditions. Due to local marine factors the nearshore SSC in the studied area is negatively correlated with the Changjiang River sediment flux (r=−0.78), which results in false negative correlation between flat elevation and river sediment flux. The paper also gives sediment dynamic and morphodynamic explanation for the above correlations. Sea level rise results in the spread of breaker zone from subtidal area to intertidal area and then increases the intertidal water energy. The larger the tidal range, the stronger the tide currents and the easier for the flat to be eroded. The higher the SSC of flood water, the easier for the sediment to deposit down. Because of correlations among the influential factors, it is difficult to give the prime one which dominates the erosion and accretion processes in tidal flats.

Preliminary check-list of the marine, shelled gastropods (Mollusca) of Golfo Dulce, on the Pacific coast of Costa Rica

Based on partly worked up material from three brief collecting excursions to the peninsular shore of Golfo Dulce, 252 species of shelled gastropods, mostly prosobranchs and pyramidellids, have been identified. This being the first report on intertidal and shallow water gastropods from the gulf, the list may be taken as a preliminary check list of this fauna clement from Golfo Dulce. Only partly sorted material from two additional trips to the gulf contains at least 100 additional species not yet identified.

Lanceispora amphibia gen. et sp. nov., a new amphisphaeriaceous ascomycete inhabiting senescent and fallen leaves of mangrove

Lanceispora amphibia gen. et sp. nov. in the Amphisphaeriaceae is described from senescent and fallen leaves ofBruguiera gymnorrhiza in mangrove forests in the Southwest Islands, Japan. The fungus produces immersed ascomata in leaf tissue, cylindrical asci with an apical ring staining blue with iodine, and oblanceolate ascospores with a septum above the middle. Studies on the fungal succession on the mangrove leaves revealed thatL. amphibia infects senescent leaves on the tree and inhabits intertidal fallen leaves, showing the highest frequency of occurrence at the late stage of decomposition. In culture the optimal conditions for hyphal growth were 20 ppt salinity and 30°C, and those for sexual reproduction were 10 ppt salinity and 25°C. Growth at 0 ppt (fresh water) was depressed. The fungus has amphibious habits, growing on the tree and in intertidal water; and it is adapted to the high osmotic conditions in leaf tissues of the mangrove tree and to the subtropical, brackish water environment of mangrove forests.

New cyclopoids (Copepoda) from anchialine caves in Bermuda

Abstract A new species of Speleoithona and two new species of Halicyclops are described from plankton samples taken in anchialine caves in Bermuda. Halicyclops ytororoma, previously known from interstitial intertidal waters along the coast of the State of Sao Paulo, Brazil, is also found in these troglobiont samples. Speleoithona is redefined to contain the new species from Bermuda.

Horizontal and vertical gradients in sediment nutrients on mudflats in the Shannon estuary, Ireland

Spatial variability in nutrient concentrations in the intertidal sediments and pore waters has been studied along downshore transects and in core profiles at three locations in the Shannon estuary on the west coast of Ireland. The parameters measured were N, as Kjeldahl N, NO3, NO2, and NH3, and P as total P and PO4 along with a range of other environmental variables such as salinity and sediment organic content.

Rock Gunnels in Intertidal Waters of Maine

Rock Gunnels in Intertidal Waters of Maine

Analyses of recent geomorphic evolution of Gargathy Inlet, eastern shore of Virginia, U. S. A.

Gargathy Inlet is a small natural tidal inlet in the northern region of the Virginia barrier island chain. It is 100 m wide with a throat cross-sectional area of 384 m2 and an average tidal prism of 6.47×106 m3. The inside drainage system is 7.8 km long and 2.2 km wide. The main channels comprise 5.8% of the area, shallow lagoons 19.8%, andSpartina marshes 74.4% in 1970. Over the period 1851–1989 the inlet narrowed and migrated northward while maintaining a weakening downdrift offset. The nearby barrier island coastline’s rapid retreat (average rate 4.78 m/a, 138 years retreat 660 m) was accompanied by back barrier channel and lagoon filling and a decrease in intertidal water volume which was probably the main reason for the entrance narrowing. The northward migration of the inlet was related to the dredging of the Inside Passage (before 1949) and the breaching of southern Metompkin Island (since 1957) connected with the inlet system. This altered the interior tidal circulation and likely shifted northward the divide between the drainage areas of Gargathy Inlet and Metompkin Inlet. Bypassing littoral sediment from north to south, downdrift local transport reversal, and onshore welding of swash bars formed a downdrift offset. Very strong coastal storms, particularly those of 1933 and 1962, played important roles in changing inlet geometry.

Ulva lactuca as bioindicator of metal contamination in intertidal waters in Hong Kong

The use of Ulva lactuca L. as an indicator of metal contamination was assessed by analysing the levels of Mn, Fe, Ni, Cu, Zn, Cd and Pb in the alga collected from 24 intertidal sites around the Island of Hong Kong. Twelve of the sites are in the rural southern parts of the Island where the coastal waters are relatively clean. The remaining 12 sites are located in the north and within Victoria Harbour which receives, apart from industrial effluents, untreated domestic sewage from a population of some 3.5 million. The mean levels of Mn, Fe, Ni, Cu, Zn and Pb in Ulva from the urban sites were respectively 4.0, 4.6, 1.8, 2.3, 2.4 and 4.6 folds those from the rural sites. However, similar levels of Cd were found in the alga amongst all the sites. Locations of high levels of metal contamination, particularly to the eastern end of the Harbour, have been identified. Preliminary results indicate that Ulva is a good indicator of Mn, Fe, Cu, Zn and Pb contaminations.

Paleoecology of a middle Eocene mangrove biota (vertebrates, plants, and invertebrates) from southwest Texas

This is a paleoecologic analysis of a middle Eocene suite of fossils, the Casa Blanca fauna and flora. Specimens were recovered by excavation, screen washing, and core drilling in marginal marine deposits of the Laredo Formation, Claiborne Group, in Webb County, Texas, U.S.A. The associated fauna includes three invertebrate, eight chrondrichyan, six osteichthyan, one amphibian, ten reptilian, and numerous mammalian taxa. Plant megafossils and sporomorphs consist of one lycophyte, seven ferns, one conifer, and at least ten angiosperm species, including the mangrove-forming palm Nypa and members of a back-mangrove swamp forest and lowland tropical rain forest. Of special interest is the high diversity of the vertebrate fauna, unsurpassed in Paleogene Coastal Plain deposits, and the occurrence of the mangrove palynoflora in brackish water deposits, probably the first such deposits to be analyzed palynologically from the middle Eocene of the Gulf Coast. Biogeographic distributions of living relatives of the Casa Blanca biota are used to reconstruct the paleoecological conditions which existed in Webb County, Texas, during deposition of the fossil-bearing strata. These species indicate that the depositional setting was an estuarine Nypa mangrove-complex growing under tropical conditions. Intertidal waters, warmer than 24°C and with little wave action, had salinities close to 10%. Chelonian remains suggest that climatic conditions resembled those now found in coastal areas of southern New Guinea and northern Australia, or those prevailing in southeastern Mexico and northeastern Central America.

The influence of seabird guano on the biological structure of rocky intertidal communities on islands off the west coast of southern Africa

On the rocky west coast of southern Africa, the growth rate of intertidal algae appears to be limited by the availability of inorganic nutrients. At offshore islands, where colonies of seabirds breed and roost, intertidal waters are enriched with nutrients from dissolved guano, and the growth rate of algae is enhanced. Comparison of mid-intertidal communities from island and nearby mainland shores showed that mainland communities were characterized by the absence of foliose algae and sessile filter-feeders, and the presence of large areas of "vacant", rocky surface. On island shores, mats of foliose algae dominated mid-intertidal communities and herbivorous limpets grew more rapidly and attained larger sizes. Dense populations of African black oystercatchers, which feed on limpets, occurred on island shores, but they were absent from mainland shores. The effects of nutrient enrichment at islands were evident, not only in the rate of primary production, but also in interactions between organisms at higher trophic levels and in the structure and functioning of the intertidal community as a whole.

PHYSIOLOGICAL CHARACTERIZATION OF SIX LIPID‐PRODUCING DIATOMS FROM THE SOUTHEASTERN UNITED STATES1

ABSTRACTSix strains of diatoms from intertidal waters were isolated as part of the SERI Aquatic Species Program collection and screening effort: Amphiprora hyalina Greville, Cyclotella cryptica Reimann, Lewin & Guillard, Navicula acceptata Hustedt (two strains, NAVIC6 and NAVIC8), Navicula saprophila Lange‐Bertalot & Bonik, and Nitzschia dissipata (Kütz.) Grunow. Among numerous algal strains isolated as part of this collection effort, these six strains showed rapid growth and elevated lipid content in preliminary screening experiments and were chosen for further physiological characterization. N. dissipata grew most rapidly at 25°C, whereas the other five strains grew best at 30–35°C. Salinity tolerance varied among strains, with maximal growth occurring at the following conductivities: 10–60 mS.cm−1 (A. hyalina and N. acceptata NAVIC8), 10–35 mS.cm−1 (C. cryptica), 20–45 mS.cm−1 (N. acceptata NAVIC6), 10 mS.cm−1 (N. saprophila), and 20–35 mS.cm−1 (N. dissipata). The diatoms also differed in their utilization of nitrogen sources with A. hyalina growing optimally with either nitrate or urea; N. acceptata NAVIC6, with either nitrate or ammonium; C. cryptica, N. acceptata NAVIC8, and N. dissipata, with nitrate; and N. saprophila, with urea. Under optimal conditions, A. hyalina grew at 2.0 doublings. day−1; C. cryptica grew at 3.0 doublings. day−1. Each Navicula strain had a growth rate of 3.8 doublings. day−1, and N. dissipata grew at 2.6 doublings.day−1. All six strains had lipid contents in excess of 37% ashfree dry weight (AFDW) under nutrient‐limited conditions, with N. saprophila having the highest lipid content at 48% AFDW.

Integrated Responses to Salinity Fluctuation

SYNOPSIS. Continuous and discontinuous intertidal waters both experience fluctuations in salinity frequently accompanied by changes in temperature, levels of dissolved gases and pH. A multidimensional approach to environmental fitness may therefore be more representative of natural conditions in the intertidal zone. Various combinations of environmental factors are discussed including salinity/temperature, and salinity/O2 tension. Salinity will directly affect osmotic and ionic regulation and indirectly affect acid-base balance and various components of the respiratory system including ventilation, gas exchange, perfusion, O2 transport by the respiratory pigment and utilization at the tissues. Additional areas covered in this review article are osmotic problems faced by air-breathing aquatic intertidal animals, ontogenetic changes in osmoregulatory capabilities and a comparison of steady state (square wave) versus sinusoidal (cyclical) salinity changes.

The influence of coastal upwelling on the functional structure of rocky intertidal communities.

Relationships between organisms at all trophic levels are influenced by the primary productivity of the ecosystem, and factors which enhance rates of primary production may modify trophic relationships and community structure. Nutrient enrichment of intertidal and nearshore waters leads to enhanced production by intertidal algae, and it was hypothesized that where rocky shores are washed by nutrient-rich upwelled waters, the intertidal communities should show a characteristic functional structure, based on the effects of enhanced primary production. Study sites were chosen on rocky shores in southern Africa, central Chile and the Canary Islands, in areas with and without coastal upwelling, and mid-shore community structure at these sites was analysed in terms of the abundance of certain functional guilds of organisms.It was found that algal cover and the biomass of herbivorous limpets supported per unit area on rocky shores were significantly greater in regions of coastal upwelling than in regions where upwelling did not occur. Ground cover by sessile filter-feeding organisms was significantly greater on shores in non-upwelled areas. However, correspondence analysis showed no functional aspect of intertidal community structure that was characteristic of coasts washed by upwelled waters. Primary reasons for this are probably the large variations in the nature of nutrient enrichment that accompanies upwelling, and in the nutrient status of non-upwelled areas. Other factors are man's exploitation of intertidal organisms and differences in the genetic origins of the intertidal species involved.

Juvenile Development of Clibanarius sclopetarius (Herbst, 1796) (Crustacea: Paguridea: Diogenidae) in the Laboratory

The present study deals with the juvenile morphology of Clibanarius sclopetarius (Herbst, 1796) reared in the laboratory. Ovigerous females were collected in intertidal and shallow estuarine waters at Sao Sebastiao on the northern coast of the state of Sao Paulo, Brazil. Hermit crabs were maintained in filtered sea water in a climatically controlled room at 25 ? 2?C until hatching. Larvae were cultured individually with nauplii of Artemia salina as food. Ten or more crab instars after megalopa were obtained, of which five were studied intensely and their most representative structures illustrated and described. The developmental period of C. sclopetarius until the fifth juvenile crab instar was completed in 171 days (mean value) from hatching. Sexual dimorphism was evidenced by the appearance of secondary sexual characteristics in the fifth juvenile instar. The postembryonic development of decapod crustaceans is generally characterized by three distinct stages: a zoeal or larval stage involving several instars separated by ecdysis which vary in number according to the species, a megalopa stage consisting of a single instar, and a juvenile or postlarval stage starting from the first ecdysis undergone by the megalopa, and continuing through a varying number of juvenile crab instars, until the definitive adult form is attained. The end of the juvenile stage is not as distinct as that of the larval one, because of the difficulty in recognizing when the animals are functionally capable to reproduce. It could be defined as a period in which the external morphological structures become similar to those of the adults.