Biological Differences between Brackish and Fresh Water-Derived Aedes aegypti from Two Locations in the Jaffna Peninsula of Sri Lanka and the Implications for Arboviral Disease Transmission

The mainly fresh water arboviral vector Aedes aegypti L. (Diptera: Culicidae) can also undergo pre-imaginal development in brackish water of up to 15 ppt (parts per thousand) salt in coastal areas. We investigated differences in salinity tolerance, egg laying preference, egg hatching and larval development times and resistance to common insecticides in Ae. aegypti collected from brackish and fresh water habitats in Jaffna, Sri Lanka. Brackish water-derived Ae. aegypti were more tolerant of salinity than fresh water-derived Ae. aegypti and this difference was only partly reduced after their transfer to fresh water for up to five generations. Brackish water-derived Ae. aegypti did not significantly discriminate between 10 ppt salt brackish water and fresh water for oviposition, while fresh water-derived Ae. aegypti preferred fresh water. The hatching of eggs from both brackish and fresh water-derived Ae. aegypti was less efficient and the time taken for larvae to develop into pupae was prolonged in 10 ppt salt brackish water. Ae. aegypti isolated from coastal brackish water were less resistant to the organophosphate insecticide malathion than inland fresh water Ae. aegypti. Brackish and fresh water-derived Ae. aegypti however were able to mate and produce viable offspring in the laboratory. The results suggest that development in brackish water is characterised by pertinent biological changes, and that there is restricted genetic exchange between coastal brackish and inland fresh water Ae. aegypti isolates from sites 5 km apart. The findings highlight the need for monitoring Ae. aegypti developing in coastal brackish waters and extending vector control measures to their habitats.     

Rare charophytes in Scotland's coastal saline lagoons

Summary

Recently collected data comparing the distribution and performance of the rare lagoonal charophyte Lamprothamnium papulosum across a number of UK coastal lagoon sites, including nine sites in the Western Isles, is presented. The surveys revealed that the species occurred over a wide range of salinities but was absent from sites with high phosphorus concentrations. The sites in the Western Isles held the most extensive populations and were least threatened by nutrient pollution. The discovery of two other endangered and vulnerable charophytes of brackish water, Tolypella nidifica and Chara baltica, at two of the Western Isles sites further highlights the importance of Scotland's saline lagoon resource. The use of the autoecological data on salinity and nutrient conditions for supporting Biodiversity Action Plan implementation for Lamprothamnium papulosum and for saline lagoon conservation in general is considered. Status summaries for all the charophyte species of brackish water recorded in Scotland are also provided.     

Monitoring of Na<Superscript>+</Superscript>/K<Superscript>+</Superscript>-ATPase mRNA expression in the cinnamon clownfish, <Emphasis Type="Italic">Amphiprion melanopus</Emphasis>, exposed to an osmotic stress environment: profiles on the effects of exogenous hormone

We examined changes in the expression of Na⁺/K⁺-ATPase mRNA in the gills of the cinnamon clownfish using quantitative real-time PCR in an osmotically changing environment [seawater (35 psu; practical salinity unit, 1 psu ≈ 1‰) → brackish water (17.5 psu) and brackish water with prolactin]. The expression of Na⁺/K⁺-ATPase mRNA in gills was increased after the transfer to brackish water, and the expression was repressed by prolactin treatment. Also, activities of gill Na⁺/K⁺-ATPase and plasma cortisol levels increased after the transfer to brackish water and were repressed in brackish water with prolactin treatment. Na⁺/K⁺-ATPase-immunoreactive cells were almost consistently observed in the gill filaments, but absent from the lamella epithelia. The plasma osmolality level decreased in brackish water, but the level of this parameter increased in brackish water with prolactin treatment during salinity change. These results suggest that the Na⁺/K⁺-ATPase gene plays an important role in osmoregulation in gills, and prolactin improves the hyperosmoregulatory ability of cinnamon clownfish in a brackish water (hypoosmotic) environment.     

The impact of Pseudomonas putida UW3 and UW4 strains on photosynthetic activities of selected field crops under saline conditions

Abstract

This research was aimed to assess the photosynthetic activities of barley (Hordeum valgare L.), clover (Trifolium repens L.), and pearl millet (Pennisetum glaucum (L.) R. Br.) under different saline conditions with two strains of Pseudomonas putida (UW3 and UW4) treatments. An exceptional observation was revealed on barley biomass ratio (288.8%) that irrigated with brackish saline water (10,000?mg/L) with the presence of P. putida UW4 strain. In general, P. putida UW3 strain was significantly increased crops biomass ratio (249.4%, 202.1%, and 212.5%) for barley, pearl millet, and clover, respectively, which were irrigated with 10,000?mg/L brackish saline water. Plant root and shoot systems were significantly increased in their length and weight reflecting the improvement of plants’ photosynthetic activities under salt stress conditions with the presence of P. putida strains. The results from pulse amplitude modulation fluorometry showed that the plants were recovered from the saline stress effect once P. putida strains were applied. The outcome of this research was highly recommended to apply P. putida strains (UW3 and UW4) with field crops for phytoremediation, in particular, where salinity (soil and/or brackish water) was environmentally challenging.     

Different egg-associated and larval development characteristics of Macrobrachium jelskii and Macrobrachium amazonicum (Arthropoda: Crustacea) in a Venezuelan continental lagoon

Summary

In Venezuela, M. jelskii and M. amazonicum are both found living in fresh waters and sometimes share the same habitat. The respective patterns of development of the two species have been compared, with reference to such parameters as egg size and number, duration and number of larval stages, and body length of the first zoea. Development of M. jelskii exhibits features characteristic of fresh water species, whereas that of M. amazonicum has features usually associated with brackish water species.     

The salinity preference of members of the genus Macroplea (Coleoptera, Chrysomelidae, Donaciinae), fully aquatic leaf beetles that occur in brackish water

Reed beetles (Donaciinae) of the genus Macroplea Samouelle, 1819 live permanently submerged. Literature indicates that Macroplea mutica occurs in brackish water, whereas Macroplea appendiculata is restricted to freshwater. The salinity preference of these two species was tested in a linear and a circular device that offered a continuous salinity gradient. The distribution of animals in the devices was monitored over at least 3 h in each of the 21 experiments. Both species preferred freshwater (salinity 0) over brackish water (salinity 10). In particular, this holds true for specimens collected in brackish water. Likewise, immediate reactions could be observed when during such experiments the direction of the gradient was reversed. While M. mutica can be regarded as a truly marine insect, this marine environment does not strictly reflect its fundamental niche with respect to salinity preference. This is in line with accumulating evidence that M. mutica can be found in freshwater habitats (and M. appendiculata in brackish water). This indicates that the species’ distribution might be influenced by other factors like host plant preference or dispersal mechanisms. It is discussed if—in spite of similar fundamental niches—differences in salinity tolerance (and hence performance in brackish water) may have contributed to speciation in the genus Macroplea.     

Head‐shape polymorphism in Japanese eels Anguilla japonica in relation to differences of somatic growth in freshwater and brackish habitats

The age, total length (L_T), head shape and skull shape were investigated for 379 Japanese eels Anguilla japonica sampled in freshwater and brackish areas of the Kojima Bay–Asahi River system, Okayama, Japan, to learn about the differentiation process of head‐shape polymorphism. The relative mouth width (ratio of mouth width to L_T) of A. japonica > 400 mm L_T collected in fresh water was significantly greater than that of fish collected in brackish water. Growth rates of mouth width and the distance from the snout to the midpoint of the eyes (the ratio of width and distance to age, respectively) were not significantly different between freshwater and brackish‐water samples, whereas the somatic growth rate (the ratio of L_T to age) of freshwater samples was significantly lower than that of brackish‐water eel samples. These results suggest that the factors affecting head and somatic growth of A. japonica are not identical. According to these results and feeding patterns in each habitat reported by another study, it is suggested that somatic growth appears to play a significant role in the differentiation process of the head‐shape polymorphism in A. japonica, with the slow‐growing fish in fresh water becoming broad‐headed and the fast‐growing fish in brackish water becoming narrow‐headed.     

A description of rodlet cells from the alimentary canal of Anguilla anguilla and their relationship with parasitic helminths

Rodlet cells in intestinal epithelia of infected and uninfected European eels Anguilla anguilla from brackish and fresh water were studied by light and electron microscopy. Deropristis inflata (Trematoda) was found in eels from brackish water, whereas eels from fresh water were infected with Acanthocephalus clavula (Acanthocephala). In a comparison between uninfected and infected eels from brackish water, a higher number of rodlet cells was recorded in the intestinal epithelia of infected fish. Evidence is presented that rodlet cells secrete their contents in a holocrine manner into the lumen of the eel intestine. The occurrence of organelles within the mature rodlet cell was rare. ? 1998 The Fisheries Society of the British Isles     

Spawning habits and embryonic development of the banded lampeye killifish Aplocheilichthys spilauchen (Duméril 1861) in ex situ fresh and brackish water environments

Aside from ornamental uses, there is growing interest in using killifishes for a multiplicity of purposes including baitfish and mosquito biocontrol. This experiment explored the spawning habits and embryonic development of the banded lampeye, Aplocheilichthys spilauchen in ex situ freshwater (0.04‰) and brackish water (5.01‰) to ascertain the captive breeding prospects for mosquito control in areas where they occur. Significantly higher number of eggs were laid in the brackish water than the freshwater (X² = 1613.0, P < 0.05), and black mop was the most preferred spawning substrate, followed by green, blue and white mops. Microscopic monitoring of embryos revealed that cleavage occurred within the first 30 min after fertilization, organogenesis commenced on average in the 25th hour and hatching in approximately 230 h. Although freshwater eggs were relatively bigger than brackish water eggs and certain embryonic developmental stages occurred faster in the freshwater than brackish water, these differences were overall not significant and had no effects on the development and hatching. The observed outcome that A. spilauchen can be optimally propagated with black mops in brackish water offers a significant step in its use for the mosquito biocontrol programme, as well as other potential uses not yet explored.     

Ascorbic Acid Biosynthesis and Brackish Water Acclimation in the Euryhaline Freshwater White-Rimmed Stingray,Himantura signifer

L-gulono-γ-lactone oxidase (Gulo) catalyzes the last step of ascorbic acid biosynthesis, which occurs in the kidney of elasmobranchs. This study aimed to clone and sequence gulonolactone oxidase (gulo) from the kidney of the euryhaline freshwater stingray, Himantura signifer, and to determine the effects of acclimation from freshwater to brackish water (salinity 20) on its renal gulo mRNA expression and Gulo activity. We also examined the effects of brackish water acclimation on concentrations of ascorbate, dehydroascorbate and ascorbate + dehydroascorbate in the kidney, brain and gill. The complete cDNA coding sequence of gulo from the kidney of H. signifer contained 1323 bp coding for 440 amino acids. The expression of gulo was kidney-specific, and renal gulo expression decreased significantly by 67% and 50% in fish acclimated to brackish water for 1 day and 6 days, respectively. There was also a significant decrease in renal Gulo activity after 6 days of acclimation to brackish water. Hence, brackish water acclimation led to a decrease in the ascorbic acid synthetic capacity in the kidney of H. signifer. However, there were significant increases in concentrations of ascorbate and ascorbate + dehydroascorbate in the gills (after 1 or 6 days), and a significant increase in the concentration of ascorbate and a significant decrease in the concentration of dehydroascorbate in the brain (after 1 day) of fish acclimated to brackish water. Taken together, our results indicate that H. signifer might experience greater salinity-induced oxidative stress in freshwater than in brackish water, possibly related to its short history of freshwater invasion. These results also suggest for the first time a possible relationship between the successful invasion of the freshwater environment by some euryhaline marine elasmobranchs and the ability of these elasmobranchs to increase the capacity of ascorbic acid synthesis in response to hyposalinity stress.     

Reproductive isolation in Chara aspera populations

Possible reproductive isolation between freshwater and brackish water populations of the dioecious charophyte Chara aspera was studied by means of cross-fertilization experiments and AFLP (Amplified Fragment Length Polymorphism). Three Swedish freshwater populations and three (German and Swedish) Baltic Sea populations of C. aspera were sampled. Cross-fertilization experiments were performed in a full combination setup of all populations and with two different salinities (0 and 10 PSU). Both freshwater and brackish water females formed about 70% more gametangia at 0 than at 10 PSU. Male individuals collected from freshwater had higher fertility than brackish water males at both salinities. 57% of all gametangia of females from freshwater developed into oospores compared to only 8% of gametangia of brackish water females. 42% of all oospores were fertilized in crosses between habitats (freshwater–brackish water) compared to 36% in crosses within habitats, the difference was not significant.Oospore and bulbil germination was investigated using propagules from freshwater and brackish water populations and incubation salinities of 0, 5, 10 and 20 PSU. None of the oospores collected from brackish water germinated. Germination of oospores and bulbils from freshwater was higher at 0 and 5 PSU than at higher salinities. Only around 40% of bulbils from brackish water germinated at 20 PSU compared to around 70% at the other three salinities. Germination of all bulbils was delayed at 20 PSU compared to other salinities.Genetic similarities (Jaccard indices of AFLP data) were higher within than between populations, but comparisons within habitat (freshwater–freshwater and brackish water–brackish water) were not different from comparisons between habitats.Our results did not identify any reproductive isolation between freshwater and brackish water populations, but indicate low gene flow between the two habitats. Oospore and bulbil germination success were highest at salinities corresponding to the conditions of their original habitat, suggesting genetic adaptation to their environmental conditions and indicating that propagules transported from freshwater to brackish water or vice versa will hardly develop into fertile plants. Additionally, brackish water plants perform poorer in all aspects of sexual reproduction than freshwater plants. Possibly, successful dispersal of oospores is not subjected to high selective pressure within the Baltic Sea where new sites easily can be colonized by means of vegetative reproduction. We assume that these adaptations will favour speciation within C. aspera and support the idea of the geologically young Baltic Sea as a “cradle of plant evolution”.     

Distribuzione del fitoplancton in un'area salmastra della Sicilia nord-orientale

Abstract

Phytoplankton distribution in a brackish area of North-Eastern Sicily -The abundance and taxonomic composition of the phytoplankton have been studied in relation to temperature, salinity and dissolved oxygen in the brackish pools of Oliveri-Tindari, a very restricted area on the Tyrrhenian coast of Sicily (Italy). The phytoplankton distribution in these pools has been subject to relatively few investigations. Although this area is not influenced by sewage and industrial effluents, some pools showed episodical high densities of phytoplankton, due to the influence of organic inputs (streams and water-bearings), and anoxic conditions.

The microalgal communities were generally characterized by chlorophyceans, although sometimes other taxa prevailed.     

Vergleichende Untersuchung der Ciliatensukzession beim Abbau von Zellstoff in marinem Brackwasser und athalassogenem Brackwasser vom Typ der Kaliwerksabwässer

Zusammenfassung Die Sukzession der Ciliaten beim Abbau von Zellstoff wurde unter Laboratoriumsbedingungen in marinem Brackwasser und in künstlichem Kaliwerksabwasser verfolgt. Im untersuchten Bereich bis hinauf zu 7 g/l Gesamtsalzgehalt verlief der Zellstoffabbau wie im Süßwasser. Bei Verwendung von Süßwasserorganismen als Impfmaterial zeigte sich mit steigendem Gesamtsalzgehalt eine Verminderung der Artenzahl gegenüber der Süßwasserkontrolle; diese Veränderung war in beiden Versalzungstypen nahezu gleich. Parallel mit der Verarmung des Artenspektrums erfolgt bei mehreren Arten eine deutliche Vermehrung der Individuenzahl in den höheren Salzkonzentrationen.

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Summary The succession of freshwater ciliates associated with the decay of cellulose was investigated in thalassogenic brackish water and in athalassogenic brackish water derived from waste water of potash works. The amount of decomposition of cellulose was the same in both sorts of brackish water (up to 7 g/l salt content) and in freshwater. When brackish water was used instead of freshwater, the number of species of ciliates decreased while the total number of individuals of Cyclidium citrullus, Euplotes affinis and others increased. The changes in the succession of ciliates were nearly the same in both sorts of brackish water.

     

Über die Besiedlung des Brackwasserbeckens der Ostsee durch Meerestiere unterschiedlicher ökologischer Herkunft

Zusammenfassung Tiere des marinen Eulitorals und des Supralitorals ertragen größere Schwankungen der Salinität als Tiere der Meerestiefe. Sie können daher weiter in Brackwasser eindringen als marine Tiefenformen. Brackgewässer jeder Tiefe stellen damit einen nur für ursprüngliche Eulitoraltiere besiedelbaren Raum dar. Nur wenige Arten können jedoch in die Tiefe vordringen (keine Pflanzen-fresser!). Das Phänomen der Brackwassersubmergenz ist ein allgemeines Charakteristikum von Brackgewässern und kein Spezialfall der Ostsee.

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On the colonization of brackish water by marine animals of different ecological origin

Summary Since animals of the marine littoral and supralitoral zones tolerate greater salinity-fluctuations than those of deep water layers they are far better adapted to colonize estuaries and brackish waters.This is why there live only few animals from the seabottom in brackish water even if it is very deep. Only animals from the littoral invade water with low or fluctuationg salinities.Those which are not restricted to surface regions (by their food — many depend on green plants) extend their range in brackish waters into deep layers since there is almost no competition.Therefore the bottom communities of the sea differ very much from the bottom communities of deep brackish waters.The extension of the range of marine littoral animals in deep brackish basins (Brackwassersubmergenz) therefore is characteristic for deep brackish-water-zones and no special case of the Baltic Sea.

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Herrn Prof. Dr. Dr. h. c. A. Remane in Verehrung zum 70. Geburtstag am 10. August 1968.     

Biochemical identification of a brackish water type ofPungitius pungitius,and its morphological and ecological features in Hokkaido,Japan

A brackish water type ofPungitius pungitius (Gasterosteidae) is newly reported from Japan. Genetic differences, based on 13 loci of 6 enzymes and muscle protein, were examined between fresh and brackish water types in the Biwase River in the eastern part of Hokkaido. The alleles onGpd, Pgi andPgm were displaced between them, even though their distributions partially overlapped in the river. The brackish water type was also statistically different from the fresh water type on the basis of three morphological characters, such as number of dorsal spines, gill-rakers and vertebrae, although ranges overlapped. Segregation of spawning sites and differing nuptial colors of the male were found between fresh and brackish water types. These facts suggest that the brackish water type is reproductively isolated from the fresh water type and that both types should be regarded as independent species.     

Differences in osmotolerance in freshwater and brackish water populations of Theodoxus fluviatilis (Gastropoda: Neritidae) are associated with differential protein expression

The euryhaline gastropod Theodoxus fluviatilis is found in northern Germany in freshwater or in brackish water habitats in the Baltic Sea. Previous studies have revealed that individuals from both habitats are not distinguishable by morphological characters or by sequence comparison of DNA encoding 16S RNA or cytochrome C. As reported in this study, animals collected in the two habitats differ substantially in their physiological ability to adapt to different salinities. Comparison of accumulation rates of ninhydrin-positive substances (NPS) in foot muscle upon transfer of animals to higher medium salinities revealed that brackish water animals were perfectly able to mobilize NPS, while freshwater animals had only limited ability to do so. In an attempt to explore whether this difference in physiology may be caused by genetic differentiation, we compared protein expression patterns of soluble foot muscle proteins using 2D gel electrophoresis and silver staining. Of the 40 consistently detected protein spots, 27 showed similar levels in protein expression in animals collected from freshwater or brackish water habitats, respectively. In 12 spots, however, protein concentration was higher in brackish water than in freshwater animals. In four of these spots, expression levels followed increases or decreases in medium salinities. In a different set of 4 of these 12 spots, protein levels were always higher in brackish water as compared to freshwater animals, regardless of their physiological situation (14 days in artificial pond water or in medium with a salinity of 16‰). The remaining 4 of the 12 spots had complex expression patterns. Protein levels of the remaining single spot were generally higher in freshwater animals than in brackish water animals. These expression patterns may indicate that freshwater and brackish water animals of T. fluviatilis belong to different locally adapted populations with subtle genetic differentiation.     

Non-pollen palynomorphs in the Black Sea corridor

There have been few studies of non-pollen palynomorphs (NPP) in Holocene brackish water environments. The Black Sea is one of the world’s largest and deepest bodies of stable brackish water and a natural laboratory for study of marine carbon cycling to anoxic sediments. The main NPP in the modern sediments of this brackish water sea are dinoflagellate cysts (dinocysts), acritarchs (mainly the prasinophytes Cymatiosphaera, Micrhystridium, Sigmopollis and Pseudoschizaea) and diverse fungal remains. Other NPP include colonial algae, tintinnids, copepod and cladoceran egg covers, testate amoebae and microforaminiferal linings. These NPP assemblages are similar to those in the marginal marine environment of the Pliocene St. Erth Beds (England), but have more abundant NPP, and virtually lack scolecodonts. In the Black Sea corridor, modern assemblages from areas with salinity >22‰ have higher percentages of microforaminiferal linings and fewer prasinophytes, colonial algae and fungal spores. Prasinophytes dominate only in mid-Holocene sediments, during a 2000 years interval of sea level transgression and sapropel deposition. Early Holocene sediments have lower dinocyst diversity, increased fresh–brackish water colonial algae (Pediastrum spp. and Botryococcus braunii), zygnemataceous spores and desmids (including Zygnema, Cosmarium), ostracod linings and fewer foraminiferal linings. These assemblages are similar to those in the Baltic Sea where the annual salinity is about 6–8‰.     

On the distribution of the Fire-bellied Toad,Bombina bombina,in Turkey

Abstract

The Lake of Köyceg¯iz (Köyceg¯iz Gölü) in southwest Turkey is influenced by several external factors such as sulfuric springs, :Mediterranean seawater and a relatively strong changing wind. These give rise to an exceptional hydrochemistry and hydrophysics, which are reflected in the phyto and zooplankton. The complicated layer structure of the lake is determined more by chemical gradients than by temperature. The water body is divided in two layers of differing hydrology. The upper layer is subject to full circulation while the lower one is strictly stratified by chemical gradients caused by the sulfuric sources and an influx of-Mediterranean water. The lake can be classified as meromictic. Subsurface freshwater springs may well influence the system, but to a lesser degree. Phyto- and zooplankton are characterized by a limited number of species and a low biomass. ’This is due to a very thin euphotic zone as well as the brackish character of the lake water.     

The halophile vegetation of the sedimentary coast of Lazio (central Tyrrhenian district,Italy)

ABSTRACT

This paper presents the results of a phytosociological survey carried out in the Lazio region (central Italy) to investigate the vegetation and conservation status of brackish habitats. Eighteen vegetation types are described, belonging to 8 alliances, 5 orders and 5 classes of vegetation. A new association and an association previously unrecorded in Italy, both assigned to the Frankenietalia pulverulentae, have been recognized. The occurrence of important floristic and vegetational features, and the potential for the development and restoration of typical ecological sequences suggest the implementation or the enhancement of conservation activities in all of the brackish sites surveyed.     

Changes in sodium,calcium and magnesium ion concentrations in sturgeon (Huso huso) urine and in kidney morphology

During adaptation to brackish water the young great sturgeon Huso huso is able to regulate its serum osmolarity and ion concentrations. After transfer from fresh water to brackish water the ion concentrations in the urine increase and the urine becomes isoosmotic to the blood serum after 24h. The Na⁺ and K⁺ concentrations in the urine increase during the first 12 h by 4.4 and 7.7 times, respectively, later decreasing again. The Mg²⁺ and Ca²⁺ concentrations in the urine increase by 3.4 and 14 times during the first 72h in brackish water and remain high thereafter. These results suggest that the kidneys play an important part in the regulation of serum osmolarity and in the removal of Ca²⁺; however, in contrast to teleosts, Mg²⁺ must be removed extrarenally. During adaptation to a hyperosmotic medium the diameters of the Malpighian bodies, the glomeruli and the diameter of the tubules initially all decrease, but the distal tubules become morphologically differentiated into two regions and the diameter of the distal section later increases again. It is suggested that this is the site of Ca²⁺ secretion into the urine.