Sediment toxicity testing of lightly contaminated dredged material in The Netherlands

In the Netherlands, the decision to permit the dumping of dredged material into the sea depends on the concentrations of about 33 chemical compounds (Anonymous, 1994a). This evaluation of dredged material quality can be improved by the use of bioassays in its assessment. In this note the use of bioassays in the evaluation of lightly contaminated marine dredged material from the Netherlands is illustrated with preliminary results of bioassays with Corophium volutator and Crassostrea gigas. It is concluded that the inclusion of bioassays in the assessment of lightly contaminated sediment is useful.     

Contamination of a dredged material disposal site La Rochelle Bay,France .The use of the acetylcholinesterase activity of Mytilus edulis L. as a biomarker of pesticides: the need for a critical approach

A single aspect of the toxic impact of a dredged material disposal site located near a mussel-farming zone was followed for eight months. Acetylcholinesterase activity (AChE) of Mytilus edulis was investigated as a biomarker for possible contamination by neurotoxic compounds (carbamates and/or organophosphorous pesticides). Our observations showed that the enzymatic activities (including AChE) of these harbour mussels were decreased in sites directly and indirectly influenced (according to hydrodynamic conditions) by the dumping of dredged sediments, suggesting possible contamination by pesticides. The strong correlations observed between AChE activity and growth parameters (length and weight) seems to show, however, that the enzyme activity is also indirectly controlled through growth restriction, which may imply limitation of the development of the nervous system in juveniles. The concentration of total proteins, as well as the spawning process also seem to disturb the assessment of AChE activity. These field observations clearly indicate that the use of this enzyme activity as a biomarker should proceed with caution. For example, the seasonal variability of such activity should be taken into account in a biomonitoring programme.     

An inexpensive bioassay aimed at the agricultural disposal of waste waters

Zusammenfassung Es wird einfache Methode beschrieben, die von S. Prát (1947) vorgeschlagen wurde. In Petri-Schalen werden Samen des Senfes (Sinapsis alba) auf Silongewebe aufgelegt und mit dem zu untersuchenden Wasser bewässert. Das Keimen der Samen, das Wachstum der Würzelchen sowie das Läangenvehältnis von Würzelchen zu dem Hypokotyl sind als Indikatoren der wasserbeschaffenheit anzusehen. Nicht nur die toxische Einwirkung, sondern auch Wasstumsförderung kann durch diese Testmethode ermittelt werden. Es wird vorgeschlagen, diese Methode besonders bei der Beurteilung des landwirtschaftlichen Zwecken dienenden Wassers und Abwasser anzuwenden, z. B. bei der Berieselung der Felder mit Abwasser, das nicht toxisch sein darf.     

The use of eryopreservation for convenient bioassay of insect organs in vitro

Abstract Pheromone glands of the female moth Helicoverpa (Heliothis) armigera and Malpighian tubules of the locust Locusta migratoria migratorioides (R&F) retained partial biological activity after eryopreservation. Pheromone glands were frozen to -70^oC in a tissue culture medium (TC-199) containing 10% of the cryoprotectant dimethylsulfoxide. Malpighian tubules, however, required initial preincubation for 24 h in a medium of high osmolarity before being frozen to -70^oC in the presence of 10% of the cryoprotectant glycerol. After rapid thawing of both organs, biological activity was compared with the respective fresh organs. Using a radiochemical assay, it was shown that previously frozen pheromone glands were stimulated by pheromone biosynthesis activating neuropeptide to the same degree as fresh pheromone glands. In addition, previously frozen Malpighian tubules were stimulated by an extract of corpora cardiaca to produce c-AMP to the same extent as fresh Malpighian tubules.     

Performance of selected indicators in evaluating the consequences of dredged material relocation and marine aggregate extraction

Eleven indicators were applied to macrofaunal species abundance data obtained from four dredged material relocation sites and four aggregate extraction sites in UK waters. Indicators were subsequently scored on a scale of 0 (very poor) to 5 (excellent) according to their performance in relation to six criteria governing their utility. Number of species (S) and number of individuals (N) generally scored highest in terms of understandability, sensitivity and linkage to the human activity whilst biotic indices were assigned relatively low scores, particularly in relation to aggregate extraction activities, according to the same criteria. As the immediate consequences of dredged material relocation and aggregate extraction activities are largely physical in nature the relative insensitivity of these indices may be explained by their dependence on species responses principally to organic enrichment. Indicators that incorporated measures of relatedness of species (i.e. average taxonomic distinctness, taxonomic breadth and average phylogenetic diversity) were assigned relatively low scores due to inconsistency in identifying spatial trends, and relative insensitivity. However, such indices may have the potential advantage of illuminating the causes as well as simply the existence of change and merit further examination. The adopted approach to quantifying indicator utility is critically examined and recommendations are made for future refinements.     

Differential response of nematode colonist communities to the intertidal placement of dredged material

The use of fine-grained maintenance dredged material for habitat enhancement has increased in recent years, particularly recharge schemes which provide a means of combating the erosion of intertidal flats and saltmarsh. This article investigates the development of meiofaunal nematode communities following a natural experiment in 2003, when fine-grained dredged material was deposited concurrently at four adjacent intertidal recharge sites on the southeast coast of the United Kingdom. A 12-month survey of nematode assemblages was carried out to compare univariate, multivariate, allometric and functional attributes of colonist communities in relation to the different environmental conditions prevailing at the four sites. Developing assemblages were increasingly affected by the spatial differences in the elevation, consolidation and exposure of bed material. The results indicated that the colonisation sequence was the result of random settling of suspended nematodes, sequential reproduction and differential survival and reproductive success of colonising species. For the first time, this experiment provided insights into the development of adaptive and functional types of meiofaunal nematodes following the intertidal deposition of uncontaminated fine-grained dredged material. This, in turn, will contribute considerably to the development of ecological models of the evolution of the large-scale placement of muddy dredged material in the intertidal environment.     

A zooplankton bioassay chamber for lab and field use

Field and laboratory study of zooplankton has been hamperedby the lack of standardized and reliable culture methods. Thispaper describes a zooplankton bioassay chamber for both laboratoryand in situ use that is easy to construct, inexpensive, andsuitable for even very small zooplankton species such as Bosmina.The chamber, which allows easy access to animals for examinationor counting, may be particularly useful in toxicity bioassays. ¹Financial Support was provided by NSF Grant # DDP 75-12949-A01and DDP 76-80652 to W.J. O'Brien.     

A comparison of 28 natural and dredged material salt marshes in Texas with an emphasis on geomorphological variables

Fourteen dredged material marshes andfourteen natural marshes along the Texas, USA, coastare compared on the basis of 1) edge: area ratios, 2)relative exposure index values, 3) elevation profiles,4) elevation of Spartina alterniflora, 5) soilorganic carbon content, 6) soil silt-clay content, and7) belowground plant biomass. Although edge: areacomparisons cannot detect certain types of differencesin geomorphology, comparisons clearly show thatdredged material marshes, on average, have fewer pondsand flooded depressions than natural marshes. Comparisons of relative exposure index values suggestthat wave protection structures associated with somedredged material marshes may be overbuilt. Elevationprofiles illustrate the potential for structures suchas berms to lead to differences between dredgedmaterial marshes and natural marshes, but they alsoshow the high variability in elevation profiles thatexists among both dredged material and naturalmarshes. S. alternifloraelevations in dredgedmaterial marshes are not significantly different fromthose of natural marshes. Soil organic carbon andsilt-clay content of dredged material marshes are notsignificantly different from those of natural marshes. Although belowground biomass of dredged materialmarshes is significantly lower than that of naturalmarshes, regression analysis suggests that belowgroundbiomass will increase over time. Findings reportedhere suggest several points that should be consideredduring planning and design of dredged material marshesin Texas: 1) if an objective of marsh construction isto mimic natural marsh geomorphology, methods toincrease the amount of unconnected edge need to bedeveloped, 2) methods of effectively summarizinggeomorphic characteristics need further development,and 3) there is some evidence suggesting thatprotective structures may be over-built, and the needfor substantial structural protection should bebalanced against the costs of structures and risk ofsite failure during project design. Lastly, a methodfor increasing the amount of unconnected edge thatinvolves excavation of bay bottom before placement ofdredged material is suggested.     

Spartina alternifloramarshes on dredged material: a critical review of the ongoing debate over success

After three decades ofexperience, environmental managers continue toquestion the use of dredged material for creation andrestoration of Spartina alternifloramarshes. Different uses of the term `success' have led to someconfusion, and poor recognition of the limitations ofresearch design have contributed to confusion instudies comparing dredged material and naturalmarshes. This paper uses data from a number ofsources to compare dredged material and naturalmarshes. Quantitative analyses based on dataavailable in the scientific literature suggest thatmean values for aboveground and belowground biomass,organic carbon in sediments, polychaete densities, andcrustacean densities may differ in dredged materialand natural marshes. There is not sufficient evidenceto conclude that differences are present for othervariables, such as densities of stems, oligochaetes,or fish. Cumulative quantitative data do not supportthe contention that dredged material sites becomeincreasingly similar to nearby natural marshes overtime as a general rule, although some attributes ofindividual dredged material marshes may becomeincreasingly similar to some natural marshes. Although it is clear that dredged material marshesprovide habitat for birds, limited data suggest thatdredged material marshes may provide habitat for adifferent community of birds than natural marshes. Similarly, limited data suggest that geomorphologicalfeatures found in natural marshes are not duplicatedin dredged material marshes. In short, datasummarized from the literature suggest that dredgedmaterial marshes provide some of the functions ofnatural marshes but probably do not replace all of thefunctions of lost natural marshes.     

The bioassay of gibberellins

Summary A bioassay is described which is dependent upon the fact that gibberellin induced -amylase release from barley half-seeds is proportional to the logarithm of gibberellin concentration applied. This bioassay has been successfully applied to the estimation of gibberellin-like substances in plant extracts. The bioassay has the following advantages: 1) Release of -amylase is one step closer to the primary site of action of GA; 2) release of -amylase is not affected by solvent residues and is apparently completely specific for gibberellin; 3) release of -amylase is not affected by substances other than gibberellins present in crude plant extracts.Supported by U.S. Atomic Energy Commission Contract No. AT (11-1)-1338.     

The use of heritabilities of anthropometric measures and performance tests in personnel selection

An analogy exists between the mathematical models of psychological test theory and quantitative genetics. From this analogy we can conclude, that longitudinal correlation and heritability in the broad sense are equivalent expressions for the reliability in the long run. Since long-range prediction is the aim of index construction for personnel selection in athletics and other applied fields, we recommend to use heritability as a weighting factor for phenotypic scores in order to calculate true scores and to eliminate error variance.     

The use of insects as a bioassay for Penaeus merguiensis densovirus (PmergDNV)

The lack of available cell lines has hampered the study of viral diseases in crustaceans. This is particularly important for aquaculture which has been plagued by viral diseases since its rapid expansion to meet with the growing demand for seafood products. This study was designed to find an alternative bioassay to cell lines by investigating the use of insects as potential animal models for Penaeus merguiensis densovirus (PmergDNV). Acheta domesticus (house cricket) and Tenebrio molitor (mealworms) were challenged with approximately 1 × 10⁶ virions of PmergDNV by inoculation. PmergDNV was detected in 20% of Tenebrio molitor and 86.6% of Acheta domesticus challenged with PmergDNV. During a subsequent time course experiment, there was a non significant increase in PmergDNV titres (10^4-5 virions), reaching a maximum peak at day 5 (10⁶ copies). A threshold of PmergDNV DNA level equal to or greater than 10³ virions was necessary for mortality in Acheta domesticus. As the inoculum increased from 10³ DNA copies to 10⁴, 10⁵, 10⁶, mortality increased from 20% to 60%, 80% and 100%, respectively. This is the first evidence that insects may be directly used to study viruses from crustaceans and concludes Acheta domesticus may be used as a potential model to study Penaeus merguiensis densovirus.