Ex situ cultivation of Aplysinaaerophoba close to in situ conditions: ecological, biochemical and histological aspects

Sponges provide the largest number of biologically active natural products known from the marine environment and continue to be a very well studied phylum of marine fauna. The Mediterranean sponge Aplysina aerophoba accumulates brominated isoxazoline alkaloids such as Aplysinamisin-1, Aerophobin-2, Isofistularin-3 and the biotransformation product Aeroplysinin-1, which possesses, for example, antibiotic and cytotoxic properties. Until now, it is still being discussed which organisms – the sponge itself or associated microorganisms – are responsible for metabolite production. For cultivating Aplysina individuals under ex situ conditions, we surveyed relevant ecological factors in situ and controlled them in our aquarium system. We maintained A. aerophoba for more than 9 months and analysed changes of metabolite content and composition, microbial association as well as morphology in situ and ex situ under different light exposure. Although sponges showed slight reduction during maintenance, ex situ cultivation similar to in situ conditions provides a promising method to keep sponges and obtain their bioactive metabolites.     

Relationship between turbidity and fish diets in Lakes Waahi and Whangape,New Zealand

Abstract

Stomach contents of Gobiomorphus cotidianus,Retropinna retropinna, Gambusia affinis, and Anguilla australis were compared between two shallow lakes in the lower Waikato River basin, to examine the relationship between turbidity and diet. Lake Waahi and the south arm of Lake Whangape had been turbid (20–40 g suspended solids (SS) m^?3) and devoid of submerged macrophytes since the late 1970s and early 1980s, respectively. The main basin of Lake Whangape had been generally clearer (5 g SS m^?3) with dense beds of submerged macrophytes, but at the time of sampling (1987) water clarity had deteriorated (> c. 10 g SS m³) and submerged macrophytes had declined. The mysid Tenagomysis chiltoni was an important prey for all species of fish from turbid water bodies but was less important in stomachs of fish in the main basin of Lake Whangape. Apparently, mysids were not an important prey in Lake Waahi before it became turbid. Chironomid larvae and pupae dominated the diets of small fish in the main basin of Lake Whangape. Fish and mysids were the most important prey of shortfinned eels in both lakes, with mysids most important in Lake Waahi. High mysid densities in the turbid water bodies provide an alternative food resource apparently compensating for those lost by fish when water clarity declined and submerged macrophytes collapsed.     

Unit pockmarks associated with Lophelia coral reefs off mid-Norway: more evidence of control by ‘fertilizing’ bottom currents

High-resolution topographic mapping of Norwegian deep-water Lophelia coral reefs and their immediate surrounding seafloor has disclosed striking associations with small (<5?m diameter) ‘unit’ pockmarks. A total of four study areas with Lophelia reefs and unit pockmarks are here described and discussed. At the large Fauna reef, which spans 500?m in length and 100?m in width (25?m in height), there is a field of 184 unit pockmarks occurring on its suspected upstream side. Three other, intermediate-sized Morvin reefs are associated with small fields of unit pockmarks situated upstream of live Lophelia colonies. For two of the latter locations, published data exist for geochemical and microbial analyses of sediment and water samples. Results indicate that these unit pockmarks are sources of light dissolved hydrocarbons for the local water mass, together with nutrient-rich pore waters. It is suggested that the ‘fertilized’ seawater flows with the prevailing bottom current and feeds directly into the live portion of the Lophelia reefs. With an estimated growth rate of ~1?cm per year for the Morvin Lophelia corals, it would take between 1,000 and 2,000?years for the reefs to colonize the closest unit pockmarks, currently occurring 10–20?m from their leading (live) edges.     

Anthropogenic impacts on nitrogen fixation rates between restored and natural Mediterranean salt marshes

To test the effects of site and successional stage on nitrogen fixation rates in salt marshes of the Venice Lagoon, Italy, acetylene reduction assays were performed with Salicornia veneta‐ and Spartina townsendii‐vegetated sediments from three restored (6–14 years) and two natural marshes. Average nitrogen fixation (acetylene reduction) rates ranged from 31 to 343 μmol C₂H₄·m^?2·h^?1 among all marshes, with the greatest average rates being from one natural marsh (Tezze Fonde). These high rates are up to six times greater than those reported from Southern California Spartina marshes of similar Mediterranean climate, but substantially lower than those found in moister climates of the Atlantic US coast. Nitrogen fixation rates did not consistently vary between natural and restored marshes within a site (Fossei Est, Tezze Fonde, Cenesa) but were negatively related to assayed plant biomass within the acetylene reduction samples collected among all marshes. Highest nitrogen fixation rates were found at Tezze Fonde, the location closest to the city of Venice, in both natural and restored marshes, suggesting possible site‐specific impacts of anthropogenic stress on marsh succession.     

Numerical and Experimental Analysis of A Ducted Propeller Designed by A Fully Automated Optimization Process Under Open Water Condition

A fully automated optimization process is provided for the design of ducted propellers under open water conditions, including 3D geometry modeling, meshing, optimization algorithm and CFD analysis techniques. The developed process allows the direct integration of a RANSE solver in the design stage. A practical ducted propeller design case study is carried out for validation. Numerical simulations and open water tests are fulfilled and proved that the optimum ducted propeller improves hydrodynamic performance as predicted.     

A review of definitions of the Himalayan Main Central Thrust

International Journal of Earth Sciences - Most workers regard the Main Central Thrust (MCT) as one of the key high strain zones in the Himalaya because it accommodated at least 90&nbsp;km of...     

Cretaceous metamorphism in the Austroalpine Matsch Unit (Eastern Alps): The interrelation between deformation and chemical equilibration processes

In the polymetamorphic Austroalpine Matsch Unit (European Eastern Alps) Cretaceous upper greenschist facies metamorphism overprinted Variscan and Permian magmatic and metamorphic assemblages. Mineral compositional and (micro-)structural data of metapelites and metapegmatites document different mechanisms of interrelated deformation and (re-)equilibration during Cretaceous overprinting: i) Microfractures in relic garnet represented pathways for material transport, and thus established material exchange between intragranular domains and the matrix. Major element equilibration by fast diffusion along microfractures contrasts with limited volume diffusion in adjacent host garnet. ii) Syn-tectonic breakdown of staurolite initially to paragonite, then chloritoid allows correlating reaction progress with the formation of different fracture sets. iii) Syn-tectonic mineral growth with shape-preferred orientation in foliation domains contrasts with radial growth in microlithons and strain shadows of the mylonitic foliation. iv) Syn-tectonic unmixing of pre-existing oligoclase (an_14–16) produced fine-grained aggregates of two supposedly coexisting plagioclase-phases (an_3–6 and an_20–25) in strain shadows of the oligoclase-clasts. v) Pre-existing deformation-induced heterogeneities in the spatial distribution of phases and their preferred orientation influence the kinetics of phase equilibration. Understanding the mechanisms of the mutual interrelation between deformation and phase equilibration is a prerequisite for deducing PT-constraints from strained metamorphic rocks. New garnet—whole rock Sm-Nd data from metapegmatites indicate their emplacement at 263–280 Ma and provide an important age constraint on the interrelated deformation and re-equilibration processes.     

Significance of quaternary sea-level fluctuations for delta construction along the Brazilian coast

Many important areas of Quaternary deltaic sedimentation along the Brazilian coast are practically unknown in the geologic literature, especially outside Brazil. Our studies show that these areas, previously considered as highly destructive wave-dominated deltas of Holocene age, were affected by a wave-dominated phase during the Pleistocene, succeeded by highly constructive, intralagoonal stage in the Holocene, in turn followed by wave-dominated deltaic sedimentation that continues until today. The geologic evolution of these coastal plains is exemplified here by the Doce River mouth area, State of Espírito Santo, where relative sea-level fluctuations during the Quaternary played an important role in the construction of the deltaic complex.