Phylogeny of the Alismatales (Monocotyledons) and the relationship of Acorus (Acorales?)

A phylogenetic analysis of the early branching lineages of the monocotyledons is performed using data from two plastid genes (rbcL and matK), five mitochondrial genes (atp1, ccmB, cob, mttB and nad5) and morphology. The complete matrix includes 93 terminals representing Acorus, the 14 families currently recognized within Alismatales, and numerous lineages of monocotyledons and other angiosperms. Total evidence analysis results in an almost completely resolved strict consensus tree, but all data partitions, genomic as well as morphological, are incongruent. The effects of RNA editing and potentially processed paralogous sequences are explored and discussed. Despite a decrease in incongruence length differences after exclusion of edited sites, the major data partitions remain significantly incongruent. The 14 families of Alismatales are all found to be monophyletic, but Acorus is found to be included in Alismatales rather than being the sister group to all other monocotyledons. The placement is strongly supported by the mitochondrial data, atp1 in particular, but it cannot be explained as an artifact caused by patterns of editing or by sampling of processed paralogues.     

Metabolism of cytidine (5′)-diphosphocholine (cdp-choline) following oral and intravenous administration to the human and the rat

We examined the effects of cytidine (5′)-diphosphocholine (CDP-choline) on plasma levels of cytidine, choline, and unchanged CDP-choline among normal volunteers receiving the substance orally or intravenously, and rats receiving it intravenously. Two hours after a single oral dose (2g), plasma choline levels were increased by 48% and plasma cytidine by 136%. Among subjects receiving three doses (2g each) at two-hour intervals, plasma choline peaked (30% over baseline) 4 h after the initial CDP-choline dose, while plasma cytidine levels continued to increase for at lest 6 h, at which time they were five times basal levels (P < 0.01). Intravenously-administered CDP-choline was rapidly hydrolysed, in both the human and the rat. In humans given the CDP-choline by infusion over 30 min, plasma CDP-choline fell to undetectable levels almost immediately after the end of the infusion period; plasma choline and cytidine peaked at that time, but their concentrations remained significantly elevated for at least 6 h. In rats given a bolus injection of CDP-choline, five minutes earlier, the unchanged compound was also undetectable in plasma, while plasma cytidine levels increased markedly and remained elevated for at least 60 min. These observations show that CDP-choline is converted to at least two major circulating metabolites, choline and cytidine. Since both of these compounds are used in the biosynthesis of phosphatidylcholine, both may be involved in the long-term effects of the CDP-choline.     

Adriano Buzzati-Traverso and the foundation of the International Laboratory of Genetics and Biophysics in Naples (1962–1969)

Despite a long tradition of research in applied genetics, particularly in agricultural research, in Italy the transition to the new knowledges and techniques of molecular biology was long and difficult. Political and financial constraints made academic institutions very slow to grasp the importance of molecular approaches to biology and medicine. In fact, the main studies concerning problems of molecular biology took place inside non-academic institutions. We reconstruct the complex paths leading to the birth of the International Laboratory of Genetics and Biophysics (LIGB) in Naples, and describe its work and activities in the period in which it was directed by its creator, Adriano Buzzati-Traverso, between 1962 and 1969. The origins of the LIGB are inextricably bound to the growth of biophysical research at the University of Pavia and at the Higher Health Institute in Rome. For a short period, with the aid provided by Italian and European physicists to biological research on the effects of nuclear radiation, LIGB became a focal point in European molecular biology. In 1968 the scientific and educational activities of the LIGB dramatically fell victim to the contradictions of the Italian academic and scientific system, and to the political climate which emerged in Italy at the time.     

PKCδ and ε regulate the morphological integrity of the ER-Golgi intermediate compartment (ERGIC) but not the anterograde and retrograde transports via the Golgi apparatus

The ER-Golgi intermediate compartment (ERGIC) is an organelle through which cargo proteins pass and are being transferred by either anterograde or retrograde transport between the endoplasmic reticulum (ER) and the Golgi apparatus. We examined the effect of 80 different kinase inhibitors on ERGIC morphology and found that rottlerin, a PKCδ inhibitor, induced the dispersion of the perinuclear ERGIC into punctate structures. Rottlerin also delayed anterograde transport of vesicular stomatitis virus G protein (VSVG) from the ER to the Golgi and retrograde transport of cholera toxin from cell surface to the ER via the Golgi. RNA interference revealed that knockdown of PKCδ or ε resulted in the dispersion of the ERGIC, but unexpectedly did not inhibit VSVG and cholera toxin transport. We also found that rottlerin depolarized the mitochondrial membrane potential, as does carbonylcyanide-p-trifluoromethoxyphenylhydrazone (FCCP), an uncoupler, and demonstrated that a decrease in the intracellular adenosine triphosphate (ATP) levels by rottlerin might underlie the block in transports. These results suggest that PKCδ and ε specifically regulate the morphology of the ERGIC and that the maintenance of ERGIC structure is not necessarily required for anterograde and retrograde transports.     

Comparison of Macular Integrity Assessment (MAIA ?), MP-3, and the Humphrey Field Analyzer in the Evaluation of the Relationship between the Structure and Function of the Macula

Purpose

This study was conducted in order to compare relationships between the macular visual field (VF) mean sensitivity measured by MAIA^TM (Macular Integrity Assessment), MP-3, or Humphry field analyzer (HFA) and the ganglion cell and inner plexiform layer (GCA) thicknesses.

Methods

This cross-sectional study examined 73 glaucoma patients and 19 normal subjects. All subjects underwent measurements for GCA thickness by Cirrus HD-OCT and static threshold perimetry using MAIA^TM, MP-3, or HFA. VF and OCT in the retinal view were used to examine both the global relationship between the VF sensitivity and GCA thickness, and the superior hemiretina and inferior hemiretina. The relationship between the GCA thickness and macular sensitivity was examined by Spearman correlation analysis.

Results

For each instrument, statistically significant macular VF sensitivity (dB) and GCA thickness relationships were observed using the decibel scale (R = 0.547–0.687, all P < 0.001). The highest correlation for the global (R = 0.682) and the superior hemiretina (R = 0.594) GCA thickness-VF mean sensitivity was observed by the HFA. The highest correlation for the inferior hemiretina (R = 0.687) GCA thickness-VF mean sensitivity was observed by the MP-3. Among the three VF measurement instruments, however, no significant differences were found for the structure-function relationships.

Conclusions

All three VF measurement instruments found similar structure-function relationships in the central VF.     

Possible Linkage between the Ability to Change the Period (τ) of the Prolactin and Cortisol Rhythms in Women and Breast Cancer Risk

The 24 h profiles of plasma hormone concentrations are rhythmic. The circadian period (τ) changes in development, with seasons, and in women with different stages of the menstrual cycle. It is known that the rhythms of prolactin and cortisol are sensitive to environmental time cues, such as changes in day length and phase; however, the importance of these changes is not yet understood. This study investigates whether there is a relation between the ability of a subject to respond to external cues that are associated with seasonal changes causing alteration of the rhythm's periods in cortisol and prolactin and the epidemiologically determined susceptibility to breast cancer. It is shown that the rhythmic output pattern of prolactin and cortisol in vivo is generated by more than one oscillator and structured by more than one rhythmic component. Each cohort of American women, classified on an epidemiologic basis as high risk (HR) or low risk (LR) to develop breast cancer, expresses different rhythmic output patterns of both variables, suggesting that the genetic background as defined by the risk state is related to differences in the circadian time structure, including the ability of the subject to change the rhythm's τ. The LR cohort exhibited a statistically significant change between seasons in the rhythm's τ of both the prolactin and cortisol patterns. In contrast, the HR cohort showed no change in the rhythm's τ between seasons for prolactin and cortisol patterns. These results show that in human beings, the presence of a circannual rhythm in the circadian time structure or the ability to adapt the circadian rhythmic pattern of these variables to external cues, such as seasons, is related to the partly genetically determined risk state to develop breast cancer and may be of importance for human health.     

The photoreceptors and visual pigments of two species of Acipenseriformes, the shovelnose sturgeon (Scaphirhynchus platorynchus ) and the paddlefish (Polyodon spathula )

Scanning electron microscopy, microspectrophotometry, and spectrophotometry of digitonin extracts were employed to characterize the photoreceptors and visual pigments of two freshwater Acipenseriformes. The retinas of the shovelnose sturgeon, Scaphirhynchus platorynchus (Acipenseridae), and the paddlefish, Polyodon spathula (Polyodontidae) are dominated by large rods with long, broad outer segments. A second rod, rare and much narrower than the dominant rod, is present in Scaphirhynchus but not seen in Polyodon. The absorbance maximum of the visual pigment in the rods of Polyodon is near 540 nm; that of Scaphirhynchus near 534 nm. The retinas of both species contain substantial numbers of large, single cones, about 33% of the photoreceptors in Scaphirhynchus; 37% in Polyodon. Scaphirhynchus cone pigments have absorbance maxima near 610 nm, 521 nm and 470 nm, respectively. Polyodon cone pigments absorb maximally near 607 nm and 535 nm, respectively. All visual pigments are based on vitamin A₂. The data are compared to those from other Acipenseriformes and are discussed in terms of lifestyle and behavior. Accepted: 7 October 1998     

Lithostratigraphy and carbonate microfacies across the Permian–Triassic boundary near Julfa (NW Iran) and in the Baghuk Mountains (Central Iran)

Permian–Triassic boundary sections in the Julfa (NW Iran) and Abadeh (Central Iran) regions display a succession of three characteristic rock units, (1) the Paratirolites Limestone with the mass extinction horizon at its top, (2) the ‘Boundary Clay’, and (3) the earliest Triassic Elikah Formation with the conodont P–Tr boundary at its base. The carbonate microfacies reveals a facies change, in the sections near Julfa, within the Paratirolites Limestone with an increasing number of intraclasts, Fe–Mn crusts, and biogenic encrustation. A decline in carbonate accumulation occurs towards the top of the unit with a sponge packstone in the sections, and finally resulting in a complete demise of the carbonate factory. The succession of the ‘Boundary Clay’ differs in the two regions; thin horizons of sponge packstone are present in the Julfa region and ‘calcite fans’ of probably inorganic origin in the Abadeh Region. The skeletal carbonate factory of the Late Permian was restored with the deposition of microbial carbonates at the base of the Elikah Formation, where densely laminated bindstone, floatstone with sparry calcite spheres, and oncoid wackestone/floatstone predominate.     

PEG-ing down (and preventing?) the cause of pegloticase failure

Pegloticase is a powerful but underutilized weapon in the rheumatologist’s armamentarium. The drug’s immunogenicity leads to neutralizing antibody formation and rapid loss of efficacy in roughly one-half of all patients, which remains an impediment to broader use. New data, however, suggest that drug survival might improve with concomitant immunosuppressive agent (s), which merits further study. Efficacy appears to be unchanged when pegloticase is infused at 3-week (rather than 2-week) intervals. Stretching the time between infusions may also improve patient adherence and allow for earlier identification of transient responders.In the previous issue of Arthritis Research and Therapy, Hershfield and colleagues published a study putting forth a number of novel and potentially important findings regarding pegloticase, a powerful but underutilized weapon in the small but growing anti-hyperuricemic arsenal [1].The study examined the efficacy of pegloticase in a cohort of 30 patients with severe gout (93% tophaceous) utilizing an every 3-week infusion regimen, rather than the every 2-week schedule employed in previously published phase 3 trials. Despite the longer interval between infusions in the current study, the effectiveness of pegloticase is no worse (17/30 patients are persistent responders), and the pharmacokinetics of the drug suggest this should come as no surprise. The authors correctly note that a 3-week interval would be significantly more convenient for patients, and notably that such a regimen would also prove less costly to payors. Hershfield and colleagues’ dosing schedule would also help to identify transient responders earlier in the course of treatment – only four of 12 transient responders had uric acid >6 mg/dl 2 weeks after the first infusion (three of whom had previously been exposed to pegloticase in earlier phase 1 and 2 studies), whereas 11 of 12 transient responders had uric acid >6 mg/dl at 3 weeks (vs. only one of 17 persistent responders). For the reasons just elaborated upon, the paper demonstrates that dosing every 3 weeks may not just be as good as the current protocol, but may in some ways be superior.Hershfield and colleagues also upend the assumption that neutralizing antibodies to pegloticase are formed against uricase itself. Their paper clearly demonstrates that neutralizing antibodies develop in response to the polyethylene glycol (PEG) moiety of the drug, a finding that rebuffs a recent commentary which suggested antibodies to PEG are not pathogenic [2]. A septe and larger study (169 patients exposed to pegloticase) published in the previous issue Arthritis Research and Therapy by Lipsky and colleagues reaches the same conclusion regarding anti-pegloticase antibodies: anti-PEG antibodies are responsible for loss of efficacy rather than antibodies to the uricase enzyme itself, the latter of which rarely occur (positive more than once in only 11 subjects) and occur much later during the course of treatment, long after neutralizing anti-pegloticase antibodies have developed [3]. This larger study also demonstrates that an anti-pegloticase antibody titer >1:2,430 generally predicts loss of efficacy to the drug.Finally, and not least of all, Hershfield and colleagues’ smaller study included post-transplant patients (who were excluded from the phase 3 studies), a population particularly susceptible to developing gout. Of seven post-transplant subjects in the study, six proved to be persistent responders (86%) [1]. Although this is an admittedly small number of patients upon which to base any conclusion, it does raise the intriguing question of whether immunosuppression might lead to less of a mounted antibody response against pegloticase, and thus to more favorable outcomes. This is no small point; patients who are placed on pegloticase generally have severe, long-standing, and refractory gout, and should be given every chance to optimize their response to a potentially transformative therapy.While this signal is worth pursuing, some questions are immediately raised: how immunosuppressed must patients be to prevent neutralizing anti-PEG antibody formation, and with what should this be accomplished? Of the small subcohort in this trial, all patients were on cyclosporine or mycophenolate mofetil, and five of seven patients were on a combination of immunosuppressive agents. In choosing an immunosuppressant for the express purpose of preventing neutralizing antibodies, the risk of these drugs would very probably outweigh any proposed benefit (cyclosporine in particular might be the least desirable immunosuppressant for a patient with severe gout, because it both increases serum uric acid levels and decreases the glomerular filtration rate).If a trial was designed to investigate this line of query, a reasonable immunosuppressive agent of choice might be methotrexate. This drug has been shown to effectively prevent neutralizing antibodies from forming against monoclonal antibodies to anti-tumor necrosis factor [4,5]. Methotrexate’s inhibitory effect may not extend to preventing antibody formation against PEG, although methotrexate has also been shown to inhibit antibody formation against the polysaccharide 23-valent pneumococcal vaccine [6]. Methotrexate might also yield the unintended benefit of acting as an anti-inflammatory agent to suppress gouty attacks. However, because patients with severe gout have multiple comorbidities that place them at higher risk for medication side effects, methotrexate should not be considered in the clinical setting in the absence of data to support its use [7]. Nevertheless, methotrexate therapy is an avenue of inquiry that is clinically relevant and needs exploration to increase the likelihood that patients who begin this powerful drug can remain on it.     

Molecular Evolution and Nucleotide Sequences of the Maize Plastid Genes for the α Subunit of Cf1 (atpA) and the Proteolipid Subunit of Cf0 (atpH)

The nucleotide sequences of the maize plastid genes for the alpha subunit of CF1 (atpA) and the proteolipid subunit of CF0 (atpH) are presented. The evolution of these genes among higher plants is characterized by a transition mutation bias of about 2:1 and by rates of synonymous and nonsynonymous substitution which are much lower than similar rates for genes from other sources. This is consistent with the notion that the plastid genome is evolving conservatively in primary sequence. Yet, the mode and tempo of sequence evolution of these and other plastid-encoded coupling factor genes are not the same. In particular, higher rates of nonsynonymous substitution in atpE (the gene for the epsilon subunit of CF1) and higher rates of synonymous substitution in atpH in the dicot vs. monocot lineages of higher plants indicate that these sequences are likely subject to different evolutionary constraints in these two lineages. The 5'- and 3'-transcribed flanking regions of atpA and atpH from maize, wheat and tobacco are conserved in size, but contain few putative regulatory elements which are conserved either in their spatial arrangement or sequence complexity. However, these regions likely contain variable numbers of "species-specific" regulatory elements. The present studies thus suggest that the plastid genome is not a passive participant in an evolutionary process governed by a more rapidly changing, readily adaptive, nuclear compartment, but that novel strategies for the coordinate expression of genes in the plastid genome may arise through rapid evolution of the flanking sequences of these genes.     

Physical and functional interaction of the active zone protein CAST/ERC2 and the β-subunit of the voltage-dependent Ca(2+) channel

In the nerve terminals, the active zone protein CAST/ERC2 forms a protein complex with the other active zone proteins ELKS, Bassoon, Piccolo, RIM1 and Munc13-1, and is thought to play an organizational and functional role in neurotransmitter release. However, it remains obscure how CAST/ERC2 regulates the Ca(2+)-dependent release of neurotransmitters. Here, we show an interaction of CAST with voltage-dependent Ca(2+) channels (VDCCs), which are essential for regulating neurotransmitter release triggered by depolarization-induced Ca(2+) influx at the active zone. Using a biochemical assay, we showed that CAST was coimmunoprecipitated with the VDCC β(4)-subunit from the mouse brain. A pull-down assay revealed that the VDCC β(4)-subunit interacted directly with at least the N- and C-terminal regions of CAST. The II-III linker of VDCC α(1)-subunit also interacted with C-terminal regions of CAST; however, the interaction was much weaker than that of β(4)-subunit. Furthermore, coexpression of CAST and VDCCs in baby hamster kidney cells caused a shift in the voltage dependence of activation towards the hyperpolarizing direction. Taken together, these results suggest that CAST forms a protein complex with VDCCs, which may regulate neurotransmitter release partly through modifying the opening of VDCCs at the presynaptic active zones.     

Larval development and morphogenesis of the sea spider Pycnogonum litorale (Ström, 1762) and the tagmosis of the body of Pantopoda

Aspects of pantopod ontogeny have been known for a long time, but specific information is available for only a few species. Our account of the postembryonic development of Pycnogonum litorale is based on laboratory-reared individuals and SEM studies. We documented particularly all early developmental stages, with emphasis on morphogenetic changes of head structures and appendages. In P. litorale the protonymphal limbs, the chelicerae and two more uniramous legs, degenerate already during the larval phase; only the third one, the ovigers, reappears in male juveniles. Other Pantopoda vary in this aspect from retention of all three protonymphal appendages to their complete reduction, as in P. litorale. Accordingly, the two post-cheliceral larval appendages are separate legs in front of the walking legs in the adults, the ‘parapalps’ and the ‘ovigers’, but they do not occur in all pantopods. The scarcity of studies of the ontogeny of Pantopoda prevents us from a more conclusive picture, but our data are promising to state that additional such studies will increase the usability of ontogenetic data for a phylogenetic analysis of Pantopoda, the crown group of the Pycnogonida. We also discuss the phylogenetic implications of our data in the light of new information from Hox genes and developmental-biological data on body segmentation and tagmosis of the Chelicerata. These suggest the homology of chelicerae and antenn(ul)ae of other euarthropods. Accepting this, we conclude that the adult pycnogonid/pantopod head, the cephalosoma, corresponds to the euarthropod head and that the protonymph with three appendage-bearing segments may represent an even shorter, possibly phylogenetically older larval type than the euarthropod ‘head larva’ bearing four pairs of appendages. In further consequence, the fourth walking legs of Pycnogonida/Pantopoda should correspond to the first opisthosomal appendages, the chilaria, of euchelicerates. This implies that within Pycnogonida the post-prosomal region became compacted during evolution to a single leg-bearing segment plus a tubular end piece. Accordingly, neither the anterior nor the posterior functional boundaries of the walking-leg region correspond to the original tagma borders.     

Aerobiological and phenological study of the main Poaceae species in Córdoba City (Spain) and the surrounding hills

This study reports on the flowering phenology of 12 Poaceae species in different types of plant cover (scrub, riverbank and pasture), with a view to creating a phenological calendar for the major species contributing most to airborne pollen concentrations. The study has been carried out from March to June between 2000 and 2013. Seventeen sampling sites in the study area were selected by accessibility, and predominantly, grasses grow in different land covers for phenological monitoring. Airborne pollen was collected using a Hirst-type volumetric spore trap. Results showed that longer phenological ranges were recorded in the wettest year and shorter ranges in the driest year. Over the study period, certain species displayed changes in the timing of flowering phenology. In pastureland and scrubland, a slight phenological delay over the study period has been recorded. In pastureland, some species—i.e., Bromus madritensis, B. diandrus and B. hordeaceus, Hordeum leporinum and Stipa capensis—displayed a delay in the timing of phenophases over the study period, including B. hordeaceus and B. madritensis on riverbank. Dactylis glomerata and Trisetaria panicea in scrub have been the only species with a clear advance; B. diandrus and B. madritensis a clear flowering delay. Lolium rigidum, Dactylis glomerata, Aegilops geniculata, in scrub, riverbank and pasture, and Arrhenatherum album, only in scrub, full flowering coincided with pollen peak in some populations during several years.     

Light- and Scanning-Electron-Microscopic Analyses of the Plica glossoepiglottica lateralis of the neonate and adultPan troglodytes troglodytes — Blumenbach (1799)

A unique type of papillae is evident in the plicae glossoepiglotticae laterales of the tongue ofPan troglodytes troglodytes. Areas of occurrence show flat lobes of varying length with elongated miniature processes on their free tips. The function of these papillae is presumably the convection of liquid food into the pharynx (along with the lateral folds). Furthermore, it is assumed that the papillae are sensory organs which relay taste, temperature, pain, and pressure, similar to the papillae filiformes of the tongue of other mammalia (Kunze 1969). Free nerve fibres and nerve endings were found in both the epithelium and the connective-tissue. Nerve structures resembling the “Organs of Meissner” were also discovered in the subepithelial connective-tissue. Goblet cells are found in the surface layers in the epithelium of the papillae of the newborn. These are absent in the papillae of the adultPan troglodytes troglodytes. The secretion of the goblet cells functions as a mechanical and chemical protectant for the papillae.     

On micronekton and ichthyoplankton of the frontal zone of the gulf stream and subpolar waters (Polygone “Titanic”)

Results of studies of the species composition of micronektonic fish and ichthyoplankton in the frontal zone of the Gulf Stream and subpolar waters at the stationary polygone “Titanic” performed in years with different hydrological situations (2000 and 2003) are provided. In July through August of 2000 during the penetration in the polygone of warm waters of the Gulf Stream, a considerable (almost by an order of magnitude) increase in the species composition of fish due to numerous tropical and subtropical species was recorded in comparison with the period of studies in 2003, close by dates, when the region was occupied by the cold waters of the Labrador Current. In the summer of 2000, of the 80 taxonomic forms found on the polygone, 48 were represented only by larval stages of development; 27, only by juvenile and adult specimens; and 5, by both larvae and juvenile and adult specimens. The last five species include Ceratoscopelus maderensis and Lampanyctus pusillus (Myctophidae), Arctozenus risso (Paralepididae), Stomias boa (Stomiidae), and Gonostoma elongatum (Gonostomatidae). In the summer of 2003, larval fish were absent in collections, and only juvenile and adult specimens of eight species from ten families were found. The bulk of the population of micronektonic fish in this period, as in the summer of 2000, was formed by the same arcto-boreal species of myctophids Benthosema glaciale.     

Variations of the tautomeric preferences and π-electron delocalization for the neutral and redox forms of purine when proceeding from the gas phase (DFT) to water (PCM)

Quantum-chemical calculations were performed for all possible nine neutral tautomers of purine and their oxidized and reduced forms in water {PCM//DFT(B3LYP)/6?311+G(d,p)} and compared to those in the gas phase {DFT(B3LYP)/6?311+G(d,p)}. PCM hydration influences geometries, π-electron delocalization, and relative energies of purine tautomers in different ways. Generally, the harmonic oscillator model of electron delocalization (HOMED) indices increase when proceeding from the gas phase to aequeous solution for the neutral and redox forms of purine. Their changes for the neutral and oxidized tautomers are almost parallel to the relative energies showing that aromaticity plays an important role in the tautomeric preferences. Tautomeric stabilities and tautomeric preferences vary when proceeding from the gas phase to water indicating additionally that intra- and intermolecular interactions affect tautomeric equilibria. The tautomeric mixture of neutral purine in the gas phase consists mainly of the N9H tautomer, whereas two tautomers (N9H and N7H) dominate in water. For oxidized purine, N9H is favored in the gas phase, whereas N1H in water. A gain of one electron dramatically changes the relative stabilities of the CH and NH tautomers that C6H and C8H dominate in the tautomeric mixture in the gas phase, whereas N3H in water. These variations show exceptional sensitivity of the tautomeric purine system on environment in the electron-transfer reactions.     

Flora and fauna of the sublittoral hard substrata in the Oosterschelde (The Netherlands) — interactions with the North Sea and the influence of a storm surge barrier

Since 1979 the flora and fauna of the artificial rocky shores of the Oosterschelde estuary have been investigated by diving biologists.Spatial and temporal patterns of species diversity and biomass were studied and several groups of species (communities) were distinguished. A west-east gradient in species composition was found. Species distribution proved to be mainly determined by current velocities, silt and plankton concentrations in the water, underwater irradiance, and the nature of the substratum. Some indications of migration between the basin and the North Sea are shown. Biomass of the hard substratum fauna was compared with that of the soft bottom fauna; the ratio appeared to be about 1 : 2, which is surprisingly high considering the small area available for hard substratum fauna.The key to the interactions with the North Sea is found in the water movements and the volume of water passing through the mouth of the basin during each tide. The abiotic and subsequent biotic changes in the basin caused by the building of the storm surge barrier are discussed, and used to illustrate the measure of dependence of the Oosterschelde on the North Sea.     

Observations on the distribution and relative abundance of the scyphomedusan Chrysaora hysoscella (Linné, 1766) and the hydrozoan Aequorea aequorea (Forskål, 1775) in the northern Benguela ecosystem

Observations on the abundance of medusae at the surface were conducted in the northern Benguela ecosystem, over the period August 1997–June 1998. The results suggest that Chrysaora hysoscella is found inshore, whereas Aequorea aequorea tends to be found offshore. Although these relative observations are subject to bias caused by seasonal changes in the survey area, they are generally supported by the results of correlation analyses, and by the results of a more quantitative, cross-shelf trawl survey. Both species of medusae display marked patchiness, and can be very abundant. They appear to have mostly non-overlapping patterns of distribution in the upper layers of the water column, and so are able exert a consistent predation pressure across the width of the continental shelf. The estimates of biomass obtained are used as input variables to existing models of energy flow within the ecosystem.