Marine Water Species Research Articles

Analysis of the 16S–23S rDNA intergenic spacers (IGSs) of marine vibrios for species-specific signature DNA sequences

Vibrios are widespread in the marine environment and a few pathogenic species are known to be commonly associated with outbreaks of diarrheal diseases in humans due to the consumption of raw or improperly cooked seafood. However, there are also many Vibrio species which are potentially pathogenic to vertebrate and invertebrate aquatic animals, and of which little is known. In an attempt to develop rapid PCR detection methods for these latter class of vibrios, we have examined the 16S–23S intergenic spacers (IGSs) of 10 lesser-known Vibrio species and successfully developed species-specific primers for eight of them – Vibrio costicola, V. diazotrophicus, V. fluvialis, V. nigripulchritudo, V. proteolyticus, V. salmonicida, V. splendidus and V. tubiashii. The IGS amplicons were amplified using primers complementary to conserved regions of the 16S and 23S rRNA genes, and cloned into plasmid vectors and sequenced. Analysis of the IGS sequences showed that 37 ribosomal RNA ( rrn) operons representing seven different IGS types have been cloned from the 10 vibrios. The three IGS types – IGS 0, IGS IA and IGS Glu – were the most prevalent forms detected. Multiple alignment of representative sequences of these three IGS types from different Vibrio species revealed several domains of high sequence variability, which were used to design species-specific primers for PCR. The specificity of the primers were evaluated using total DNA prepared from different Vibrio species and bacterial genera. The results showed that the PCR method can be used to reliably detect eight of the 10 Vibrio species in marine waters in this study.

Visual acuity thresholds of juvenile loggerhead sea turtles (Caretta caretta): an electrophysiological approach.

Visual evoked potentials measure dynamic properties of the visual system by recording transient electric responses of neural tissue identified to correspond to a specific visual stimulus, such as light or a striped grid. In this study, visual evoked potentials were used to test the visual acuity of juvenile loggerhead sea turtles (Caretta caretta) in water. Subject animals were fitted with a Plexiglas goggle filled with filtered seawater. Stimuli of black and white striped gratings were presented to the turtles using a slide projector directing an image onto a screen via a rotatable mirror that shifted the striped pattern laterally one-half cycle. Bioelectric activity was collected using a digital averaging computer and subdermal platinum electrodes, implanted under the head scutes directly above the optic nerve and the contralateral optic tectum. To isolate the response signal from the noise, signal averaging techniques were used when collecting visual evoked potentials. The resulting response waveforms included a robust positive-negative compound that was used to track the turtle's response to visual stimulation. Acuity thresholds for these sea turtles, which were derived from linear regressions analysis of the positive-negative compound amplitudes versus stripe size, ranged from 0.130 to 0.215. This acuity level is comparable to other inshore, shallow water marine species.

Effects of marine sponge extracts on mitogen-activated protein kinase (MAPK/ERK 1,2) activity in SW-13 human adrenal carcinoma cells

Some species of marine sponge have been shown to produce metabolites with endocrine-altering and cell growth regulatory properties. Since cell division and differentiation are controlled, in part, by the mitogen-activated protein kinase-extracellular signal-regulated kinase (MAPK/ERK) cascade, we tested extracts (1.0 mg/ml) from six shallow water marine species obtained in the Florida Keys for effects on MAPK/ERK l,2 (sub-variant of EC 2.7.1.37) activity in incubations with SW-13 human adrenal carcinoma cells in culture. In these short-term incubations, extracts from two species, the purple bleeding sponge ( Iotrochota birotulata) and the West Indian bath sponge ( Spongia barbara), significantly inhibited MAPK/ERK 1,2 activity (to 51 and 44% of control levels, respectively) without altering cell survival. Western blots for phosphorylated and total ERK showed that ERK 2 predominated over ERK 1 by a factor of about 4:1 and that the phosphorylated forms of these isozymes were strongly suppressed by active extracts from both sponges. Another species, the green sponge ( Haliclona veridis), whose extract has been shown previously to activate guanylate cyclase and to inhibit adenylate cyclase in a variety of mammalian tissues, was found not to affect MAPK/ERK 1,2 in human adrenal carcinoma cultures but did lyse and kill most of these cultured cells. Extracts from the sheepswool sponge ( Hippospongia lachne) and the bleeding sponge ( Oligoceras hemorrhages) did not significantly affect either MAPK/ERK 1,2 activity or the survival of attached cells. An extract from the fire sponge ( Tedania ignis) did not alter MAPK/ERK 1,2 activity but did modestly decrease cell viability. These studies document for the first time species-specifc effects of marine sponge extracts on the MAPK/ERK 1,2 cascade and on the growth and survival of human adrenal carcinoma cells in culture.

Partitioning of food resources amongst 18 abundant benthic carnivorous fish species in marine waters on the lower west coast of Australia

The volumetric contributions made by prey and plant material to the diets of 4 elasmobranch and 14 teleost species, collected seasonally by trawling from waters along ca. 200 km of the lower west coast of Australia, have been compared. These benthic carnivores, which were all abundant and collectively contributed 83% to the total number of fish caught, represented nine families (Urolophidae, Scorpaenidae, Triglidae, Platycephalidae, Sillaginidae, Carangidae, Gerreidae, Mullidae and Pempherididae). Some species were numerous in both shallow (5–15 m) and deeper (20–35 m) waters and in both northern and southern regions, whereas others were largely confined to one of these water depths or regions. Comparisons between the diets of the different species, which utilised data collected from individuals throughout the study area, demonstrated that the dietary composition of any given species was almost invariably significantly different from that of every other species. This partly reflected the fact that, while errant polychaetes, gammarid amphipods and tanaids were ingested by all species, their contributions to the diets of the different species varied. Furthermore, echinoderms contributed to the diets of just nine species, and this was substantial only in the case of two sillaginid species, while teleosts were never consumed by six species and only made a marked contribution to the diets of the single species of platycephalid. The diet of each species underwent size-related changes, reflecting a shift from the consumption by smaller fish of prey such as amphipods, mysids and copepods, to the ingestion by larger fish of prey such as polychaetes, carid decapods, isopods and small teleosts. The interspecific and intraspecific differences in dietary compositions would spread the food resources amongst and within species, thereby reducing the potential for competition for those resources within the fish community. Non-metric multi-dimensional scaling (MDS) ordination plots emphasised that the dietary compositions of species within each family possessed some obvious similarities, reflecting similarities in body and mouth morphology and feeding behaviour. However, the extent to which the dietary compositions of the different families were similar or different was often not related to the phylogenetic relationships amongst those families. Furthermore, while differences in mouth size and morphology could sometimes be used to account for differences amongst the diets of the full suite of species, this was not always the case. Thus, the ways in which species feed and use their ancillary feeding structures were also employed to help elucidate the basis for variations in diets.

Conference

The distribution of dissolved and participate concentrations of As, Cr and V was investigated in the mixing area of the Po river in five surveys over the period March 1992-March 1995. The data obtained indicate noticeable contamination of coastal waters of the northern Adriatic with Cr but not As or V. Total dissolved concentrations for As and V were comparable with oceanic levels but were higher by a factor of 4 for Cr. These results suggest either low anthropogenic inputs of As and V, from terrigenous and atmospheric sources, or efficient removal mechanisms. The investigated metals had low reactivity during freshwater-seawater mixing and the distribution of concentrations in the dissolved and solid phases suggests that the dilution process is the main factor controlling the transport of these metals to the sea in low-to-medium solid transport conditions. Further investigations are required to elucidate the behavior of these metals during high solid transport conditions. Significant changes in the speciation of As occurred during the transition between the two end-member matrices. In the coastal waters of the northern Adriatic, the arsenite fraction in winter, and the arsenite and dimethylarsinate fractions in summer increased with respect to riverine waters. Changes in the speciation of chromium were minor, but also showed a small increase in reduced species in marine waters.

Distribution of As, Cr and V species in the Po-Adriatic mixing area, (Italy)

Abstract The distribution of dissolved and participate concentrations of As, Cr and V was investigated in the mixing area of the Po river in five surveys over the period March 1992-March 1995. The data obtained indicate noticeable contamination of coastal waters of the northern Adriatic with Cr but not As or V. Total dissolved concentrations for As and V were comparable with oceanic levels but were higher by a factor of 4 for Cr. These results suggest either low anthropogenic inputs of As and V, from terrigenous and atmospheric sources, or efficient removal mechanisms. The investigated metals had low reactivity during freshwater-seawater mixing and the distribution of concentrations in the dissolved and solid phases suggests that the dilution process is the main factor controlling the transport of these metals to the sea in low-to-medium solid transport conditions. Further investigations are required to elucidate the behavior of these metals during high solid transport conditions. Significant changes in the speciation of As occurred during the transition between the two end-member matrices. In the coastal waters of the northern Adriatic, the arsenite fraction in winter, and the arsenite and dimethylarsinate fractions in summer increased with respect to riverine waters. Changes in the speciation of chromium were minor, but also showed a small increase in reduced species in marine waters.

A simple scenario for stygobitization in Stenobermuda Schultz, 1978 (Isopoda Asellota Stenetriidae), with description of a new species from Andros Island, Bahamas

Description of a new stygobitic and troglomorphic species of Stenobermuda from a Blue Hole in the Bahamas, is an opportunity for speculation about hypogean colonization by this and by another cave-dwelling species from Bermuda, starting from populations of a widely distributed Western Atlantic shallow water marine species.

Acute toxicity of potassium permanganate to milkfish fingerlings, Chanos chanos.

Potassium permanganate (KMnO{sub 4}) is a strong oxidizing agent and is commonly used in aquatic systems to improve available oxygen, treat infectious diseases and parasites, detoxify fish poisons, and control algae. There have been some studies on the toxicity of KMnO{sub 4} to freshwater fishes, but none on brackish or marine water species. The following study was undertaken to determine the 24- and 96-h median lethal concentration (LC50) of milkfish fingerlings to KMnO{sub 4}. The study was also designed to evaluate the histopathological response of fish tissues to KMnO{sub 4} but was reported in another paper.

Role of biogenic thiols in the solubility of sulfide minerals

Efforts to account for observed trace metal concentrations in anoxic marine waters have had only limited success due in part to the lack of knowledge of the identity and concentration of the organic sulfur compounds that are present. There have been no previous attempts to measure trace metals concentrations simultaneously with the inorganic and organic sulfur species in marine waters. In addition to the conventional methods for the determination of the inorganic species, we are developing methods for the determination of the biogenic thiols and disulfides using an HPLC separation coupled to selective electrochemical detection. Preliminary results on the analysis from anoxic sediment pore waters will be presented. Current thermodynamic models describing the solubility of sulfide minerals in anoxic marine waters will be refined to include complexation of chalcophile trace metals by organic thiols.

Factors affecting thallium and chromium toxicity to marine algae

The acute toxicity of thallium and chromium to marine phytoplankton was determined in enrichment culture bioassays (1). The results indicated minimal effective concentrations of 0.7 10 − 1.1 10 −6 M thallium on Phaeodactylum tricornutum growth respectively for the monovalent and the trivalent forms. Separate studies on Dunaliella tertiolecta confirmed the higher toxicity of the monovalent form with respect to the trivalent one (0.4 10 −6 M and 0.9 10 −6 M, respectively). In experiments with Cr, the minimal effective concentration of Cr (VI) was 1 10 −4 M for both algal species in marine waters. Cr (VI) toxicity was found to be strongly dependent on mean salinity due to the competitive role of sulphate. Figure 1 Cr (III) concentrations lower than 4 10 −4 M did not significantly reduce the growth rate but produced a longer phase lag, while at concentrations of 4 10 −4 M Cr (III) no growth was observed. The toxicity of both Tl (III) and Cr (III) is shown to be reduced by complexation with EDTA.

THE EVOLUTION OF BIOLUMINESCENCE IN BACTERIA

Individuals of aerobic, saprophytic bacterial species, encountering a changing environment in which they were regularly exposed to periods of severe hypoxia, would have gained a major selective advantage in fatty acid metabolism if a mutation in a flavoprotein oxygenase permitted them to oxidize accumulated C8‐C18 aliphatic aldehydes to fatty acids at oxygen concentrations below which the cytochrome oxidase mediated electron transport pathway became inhibited. Such mutants, able to continue to metabolize exogenous lipid fatty acids under hypoxia, might have outproduced their wild type ancestors. Colonies of those mutants which utilized reduced flavin mononucleotide (FMNH2) as the flavin cofactor would have been luminous, owing to the fortuitous coincidence that the aldehyde oxygenation resulted in an enzyme‐flavin excited electronic state which emitted blue light with a high fluorescence yield. If this accidental “proto‐bioluminescence” were initially of sufficient brightness to have elicited phototactic responses in nearby motile organisms, increasing thereby detrital food sources or the potential for dispersal and colonization for the bacteria, a new and completely different selective advantage, that of bioluminescent signalling, would have arisen from the original metabolic function. This is the biochemical analog of Darwin's principle of functional change in structural continuity. It is proposed that bacterial luciferase, the FMNH2‐oxygenase in luminous bacteria, was such a mutation. The present ubiquitous distributions of luminous bacterial species in marine waters, on the surfaces of marine animals and as symbionts in the specialized light organs and digestive tracts of many fish species have resulted from subsequent environmental selection and optimization for this original proto‐bioluminescent reaction. By extension it is suggested whereas “protobioluminescence” arose in many species independently whenever metabolic oxygenation of a substrate resulted in an adventitiously efficient chemiluminescence, the function of bioluminescence arose only upon favorable interaction between the “proto‐bioluminescence” and its ecosystem.

Speciation in western Atlantic stone crabs (genus Menippe): the role of geological processes and climatic events in the formation and distribution of species

Electrophoretically detectable variation in 38 proteins and color morphology were used to determine the evolutionary relationships of crabs of the genus Menippe (Xanthidae) in the southeastern USA. Both allele frequencies (=genotype) and color morphology (=phenotype) showed that one species, Menippe mercenaria, is probably a taxonomic supergroup composed of two taxa (semispecies). One taxon (the western Gulf form) is distributed from northwest Florida westward through Texas. The second (the peninsular Florida form) ranges through the Florida peninsula from northwest to east central Florida, and in North Carolina. The taxa appear to have hybridized in two discrete regions: in the Gulf of Mexico (northwest Florida) and in the Atlantic Ocean (east central Florida to South Carolina). The agreement of patterns of geographic variation in genotype and phenotype with the geological record and estimated times of divergence based on genetic distances suggests that the observed patterns are the product of the influence of Late Cenozoic changes in climate and geology. The Atlantic zone of hybridization was formed prior to the closure of the seaway across north Florida connecting the Gulf of Mexico and the Atlantic, and the northwest Florida zone at some time subsequent to the closure. The present distribution, and the location of zones of hybridization, between the two semispecies of M. mercenaria illustrate the importance of the interaction of historical geological and climatic events with ecological boundaries in determining the distribution and interactions of shallow water marine species.

Tintinnids of Chesterfield Inlet, Northwest Territories

Tintinnids were numerically dominant in plankton samples collected from Chesterfield Inlet, Northwest Territories, in September 1978. Thirteen species were identified, 11 of which are new records for the Hudson Bay area. Tintinnopsis fimbriata and T. angusta were the most numerous tintinnids in the upper estuary at salinities below 24‰; their cell numbers were significantly positively correlated to temperature. Parafavella denticulata was the most abundant species in marine waters but it penetrated the estuary to salinities as low as 4‰. Cell numbers and volumes of P. denticulata were significantly positively correlated to salinity and negatively to chlorophyll; this species appeared to act as an almost conservative indicator of marine influence in this estuary. The distributions of the two Tintinnopsis species were not so readily explained, but maximum numbers of T. fimbriata and T. angusta corresponded to a phytoplankton maximum at station 29 in the middle estuary.