Brackish Water Ecosystem Research Articles

Beach morphology and coastal protection along Ennore coast in the north of Chennai city, southeast India

Baseline information on the beach Abstract: morphology along the Ennore coast, an industrial hotspot region in the East coast of Bay of Bengal, is presented. In order to assess the effect of human interference on the coastal zone, a baseline survey of the coastline is considered important. Such information enables to predict the future coastal morphology and settings. Based on the baseline data created, this study predicts that the accretion noticed in the southern side of the Ennore port will affect the port entrance channel in the future course. Therefore it warrants for immediate mitigation measures to curtail such accretion and also recommends for keeping the Ennore creek mouth open permanently. Ennore creek also serves as the coolant source for the two thermal power plant units. The study also put forward certain other mitigation measures which are relevant in the present event of developments. Adjacent to Pulicat Lake, the erosion is continuously taking place at an alarming rate making vulnerable for a striking storm to wash away the villages under the sea. It may also lead to the merger of the Pulicat Lake into the Bay of Bengal, thereby the brackish water ecosystem of the lake may altogether disappear causing several ecological and social problems. The study concludes that a long-term integrated coastal monitoring is the need of the hour

The complete mitochondrial genome of the Hawaiian anchialine shrimp Halocaridina rubra Holthuis, 1963 (Crustacea: Decapoda: Atyidae)

Shrimp of the family Atyidae are important members of nearly all tropical (and most temperate) fresh and brackish water ecosystems in the world. To date, a complete mitochondrial genome from this important crustacean group has not been reported. Here, we present the complete mitochondrial DNA sequence of the Hawaiian atyid Halocaridina rubra [Holthuis, L.B., 1963. On red coloured shrimps (Decapoda, Caridea) from tropical land-locked saltwater pools. Zool. Meded.16, 261–279.] (Crustacea: Decapoda: Atyidae). The genome is a circular molecule of 16,065 bp and encodes the 37 mitochondrial genes (13 protein-coding, 22 tRNAs, and two rRNAs) typically found in the metazoa. Gene order and orientation in the H. rubra mitochondrial genome is syntenic with most malacostracans that have been examined to date. Of special note is the absence of the dihydrouridine (DHU) arm stem from tRNA Tyr and the use of CCG as an initiation codon for cytochrome oxidase subunit I ( COI); these represent the first reported examples of such phenomena in the Malacostraca. Phylogenetic analyses utilizing complete mitochondrial sequences from other malacostracans place H. rubra as sister to Macrobrachium rosenbergii, which also belongs to the Infraorder Caridea. However, the placement of this infraorder, as well as the Infraorder Dendrobrachiata, in the phylogeny of the Decapoda varied depending on outgroup selection. Data from additional mitochondrial genomes, such as basal decapods like the Stenopodidea, should contribute to a better overall understanding of decapod phylogenetics.

Palaeomagnetic Results from the Sarmatian/Pannonian Boundary in North-Eastern Croatia (Vranovi? Section, Našice Quarry)

The Sarmatian/Pannonian boundary in the Central Paratethys basin is marked by a major regressive event, which isolated the basin from the open sea and resulted in a palaeoenvironmental change from restricted marine to brackish water ecosystems. The exact age of this environmental change is still ambiguous since direct age control on the boundary interval is lacking, mainly due to the scarcity of suitable sections. The Vranovi? section in the Našice Quarry in Croatia, however, is relatively long and continuously exposed. A detailed sedimentological and biostratigraphic study indicates that it contains the Sarmatian/Pannonian boundary and that it reflects the same palaeoenvironmental trend as other Paratethyan sequences. Here, we present palaeomagnetic and rock magnetic results from the Vranovi? section, based on 183 sampled levels distributed along 55 m of cyclically bedded limestones and marls. Rock magnetic data indicate the presence of maghemite or haematite in the Sarmatian deposits and low contents of magnetite in the Pannonian rocks. Thermal demagnetization results indicate dominantly normal polarities, and the mean direction closely coincides with the present-day field direction at Našice. We conclude that magnetostratigraphic age control cannot be derived for the Vranovi? section because of a dominant secondary (post-tilt) magnetization. Consequently, a firm numerical age based on magnetostratigraphy cannot be assigned to Sarmatian/Pannonian boundary events from this section.

Brackish water ecosystem restoration based on integrated water system design

Brackish water ecosystem restoration based on integrated water system design Despite their current location within a primary agricultural area, most of the creek remnants in the Dutch clay polder areas have a high potential for recovery into healthy ecosystems. Like most areas in the Netherlands the clay polders are densely populated. Therefore multifunctional land use is encouraged and different types of land use coexist within small distances from each other. As a result water conflicts occur: agricultural land use requires deep groundwater levels and causes eutrophication by spreading nutrients into the water system, while existing ecosystems within and around the creek remnants need wetland conditions and low nutrient levels. Furthermore periods of high discharge cause flooding of arable land. Extreme measures like filling in ditches and increasing water levels are needed to achieve the water targets for wetlands around the creeks. On the other hand, the effects of these measures easily cause water logging in nearby agricultural areas. We introduce an integrated approach for the restoration of creek ecosystems. Both the complex interaction of groundwater, surface water and ecology and the limiting conditions imposed by adjacent agricultural land use, spatial developments and regulatory settings like the European Water Framework Directive are thereby taken into account. A highly integrated set of measures is proposed creating optimal conditions for both high agricultural production and flourishing creek ecosystems.

Reconstruction of an Aquatic Food Web: Viking Haithabu vs. Medieval Schleswig

In the last two decades, the analysis of stable isotopes of carbonate and collagen from archaeological bone finds became a useful tool in the reconstruction of ancient food webs. Nevertheless there is still only little information available about aquatic food webs, in particular concerning brackish water ecosystems. The Schlei Fjord in Schleswig-Holstein, Germany, is such an ecosystem and was investigated to determine stable isotopic values for nitrogen, carbon and oxygen from bone collagen and carbonate in archaeological bone finds. Wild birds, mammals and fish bones from the Viking settlement Haithabu and the medieval town of Schleswig have been analyzed in this study to determine stable isotope values for marine and limnic species and to investigate possible isotopic gradients for mixing fresh water and salt water ecosystems.

Short Communication - Aquatic Oil Pollution Impact Indicators

Aquatic oil pollution impact indicators such as oil-grease, low dissolved oxygen concentration, increased biochemical oxygen demand, increased water temperature and acidity of the water are associated with aquatic habitat degradation, reduced productivity and or loss of biodiversity. These impact indicators are interrelated and connected in a chain reaction that a severe shift in any of the parameters will induce negative changes in others. For instance, introduction of significant quantities of crude oil into the aquatic ecosystem will cause increase in biochemical oxygen demand, reduction in dissolved oxygen concentration, increased temperature and pH of the water body. The resultant effect of these abnormal shifts in the impact indicators is disorders in the physiological status and reduction in the immune status of aquatic organisms, which may lead to mortality. Therefore to ensure sustainable management and optimum exploitation of the aquatic resources, it is necessary to set safe limits for the pollution impact indicators. This paper reviews the deleterious impacts of these indicators on the aquatic habitat and productivity, and establishes the safe limits for each impact indicator in relation to the freshwater, brackish water and marine ecosystems. Journal of Applied Sciences and Environmental Management Vol. 8 (2) 2004: 71-75

Diversity and distributions of circumpolar fresh- and brackish-water Mysis (Crustacea: Mysida): descriptions of M. relictaLovén, 1862, M. salemaai n. sp.,M. segerstralei n. sp. and M. diluviana n. sp., based on molecular and morphological characters

Mysid crustaceans of the Mysis relicta species group are widespread throughout the northern Holarctic and play an important role in many fresh- and brackish-water ecosystems. Earlier molecular and morphometric studies already indicated that the conventionally identified Mysis relicta sensu lato comprises several distinct species. Here we present formal taxonomic diagnoses, descriptions and an account of the distributions of Mysis relicta s. str. and three new species split from it, based on comprehensive assessment of both morphological and molecular characters (allozymes, mtDNA). M. relicta Loven s. str. is the prevalent species in lakes of Northern Europe and peripheral parts of the brackish Baltic Sea. M. salemaai n. sp. inhabits offshore habitats of the Baltic Sea and a range of lakes from the British Isles, southern Scandinavia and Karelia to coastal northern Siberia; at several sites M. relicta and M. salemaai are sympatric. M. segerstralei n. sp. has a circumpolar distribution along the Arctic coasts and islands of Eurasia and North America and also occurs in lakes of these northern regions. M. diluviana n. sp. inhabits continental freshwater lakes of the once-glaciated northern North America. The four species are characterised by unique combinations of alleles at a number of allozyme loci, and most of them by specific mitochondrial DNA lineages diverged by c. 7.5% in the COI gene sequence (cytochrome oxidase subunit I). The most important diagnostic morphological characters include the shape of the posterior emargination of carapace, length of setae on the merus of maxillipede 2, length and shape of spine-setae on maxilla endopod distal segment, number and size of lateral spine-setae on telson, and setation of thoracic endopods. A morphological key to the four species is presented.

Colonization of Brackish-Water Systems through Time: Evidence from the Trace-Fossil Record

Abstract Trace fossils in estuarine deposits of different ages have been compared to evaluate colonization history of brackish-water ecosystems and to calibrate trace-fossil, brackish-water models with respect to geologic time. This comparative analysis reveals that, although the colonization of marginal-marine, brackish-water environments was a long-term process that spanned most of the Phanerozoic, this process of invasion of fully marine organisms into restricted, marginal-marine habitats did not occur at a constant rate. Five major colonization phases can be distinguished. The first phase (Ediacaran–Ordovician) represents a prelude to the major invasion that occurred during the rest of the Paleozoic. While Ediacaran–Cambrian ichnofaunas seem to be restricted to the outermost zones of marginal-marine depositional systems, Ordovician assemblages show some degree of landward expansion within brackish-water ecosystems. Intensity of bioturbation and ichnodiversity levels were relatively low during this pha...

Holocene environmental history of the Gotland Basin (Baltic Sea)—a micropalaeontological model

Organic microfossils of a well-dated sediment core from Gotland Basin were analysed and used for the ecological interpretation of the Holocene history of this area. To avoid confusion with corrected and uncorrected 14C ages, only calendar years BP are used. In the lowermost part organic microfossils are rare, but few marine dinoflagellate cysts between 11 300 and 11 000 years BP indicate the marine Yoldia Phase. At 9800 years BP a significant environmental change is indicated by the rapid increase of freshwater dinoflagellates and pine pollen. At the end of the freshwater stage an enormous abundance increase of cladoceran remains indicates an eutrophication event between 7600 and 7400 years BP. First permanent brackish water conditions of the surface water were established at 7400 years BP and the increasing salinity reached its maximum between 6700 and 6400 years BP. Further changes in the brackish surface water ecosystem of the Gotland Basin can be found at 5500, 4400, 3000, 1000, and 800 years BP, which are thought to be mainly climatically induced.

Integrated ecological assessment of Danish Baltic Sea coastal areas by means of phytoplankton and macrophytobenthos

The Water Framework Directive (WFD) demands an integrated assessment of ecological quality based on biological parameters. In this context combined macrophytobenthos and phytoplankton data sets along the Danish Baltic Sea coast were analysed for similarities and differences in their response to abiotic variables. Zostera marina's depth limits showed a significantly negative correlation with concentrations of total-nitrogen, total phosphorus and chlorophyll a as well as with Myrionecta rubra biomass and a strongly positive correlation with Secchi depth. The results documented that selected phytobenthos and phytoplankton indicators show correlated responses to water quality. All biotic and abiotic parameters clustered in two groups, indicating two trophic states but, at the same time, also two distinct salinity classes. One class was characterised by low nutrient levels and low salinity while the other class was characterised by high nutrient levels and high salinity, indicating that the mixing of relatively nutrient poor brackish Baltic water with more nutrient rich North Sea water overruled traditional estuarine gradients in the investigated area. The results therefore allow an analysis of the eutrophication state regarding the additional influence of decreased salinity on euryhaline marine species. The consequences of the results are discussed in relation to classification systems for brackish water ecosystems.

Mitochondrial DNA variation in populations of the mussel Mytilus trossulus from the Southern Baltic

The mussel Mytilus trossulus is an important component of the Baltic brackish water ecosystem. The genetic structure of mussel (M. trossulus) populations was studied in sites along the Polish coast, Southern Baltic for two segments of mitochondrial DNA (mtDNA). The mode of inheritance of Mytilus mtDNA is termed doubly uniparental; two genomes are passed independently down the female (the F genome) and male (the M genome) lines of descent. The M genome has not been detected at high frequency in M. trossulus, thus the present study focuses on the F genome. PCR and RFLP analysis was used to characterise haplotypes in the coding region ND2-COIII; PCR was used to detect length variants in a major noncoding region. Significant differentiation between populations was observed in the frequency of 24 coding region haplotypes and 14 different length variants. For the three most frequent coding region haplotypes, two (I and III) are associated with the length variants, whereas the third (II) is monomorphic for a single variant of short length. It is suggested that variant II is derived by introgression from a related species, M. edulis, and may be resistant to expansion in the noncoding region. In both regions studied, the Ewens–Watterson test reveals significant deviations from neutrality with an excess of rare variants. This might be due to selection against slightly deleterious variants and is consistent with previously published results for Mytilus taxa. The present study also points towards the potential utility of mtDNA length variation in studies of population differentiation of Mytilus.

Molecular phylogeny of type II methane-oxidizing bacteria isolated from various environments.

Type II methane-oxidizing bacteria (MOB) were isolated from diverse environments, including rice paddies, pristine and polluted freshwaters and sediments, mangrove roots, upland soils, brackish water ecosystems, moors, oil wells, water purification systems and livestock manure. Isolates were identified based on morphological traits as either Methylocystis spp., Methylosinus sporium or Methylosinus trichosporium. Molecular phylogenies were constructed based on nearly complete 16S rRNA gene sequences, and on partial sequences of genes encoding PmoA (a subunit of particulate methane monooxygenase), MxaF (a subunit of methanol dehydrogenase) and MmoX (a subunit of soluble methane monooxygenase). The maximum pairwise 16S rDNA difference between isolates was 4.2%, and considerable variability was evident within the Methylocystis (maximum difference 3.6%). Due to this variability, some of the published 'specific' oligonucleotide primers for type II MOB exhibit multiple mismatches with gene sequences from some isolates. The phylogenetic tree constructed from pmoA gene sequences closely mirrored that constructed from 16S rDNA sequences, and both supported the presently accepted taxonomy of type II MOB. Contrary to previously published phylogenetic trees, morphologically distinguishable species were generally monophyletic based on pmoA or 16S rRNA gene sequences. This was not true for phylogenies constructed from mmoX and mxaF gene sequences. The phylogeny of mxaF gene sequences suggested that horizontal transfer of this gene may have occurred across type II MOB species. Soluble methane monooxygenase could not be detected in many Methylocystis strains either by an enzyme activity test (oxidation of naphthalene) or by PCR-based amplification of an mmoX gene.

Morphometric discrimination among four species of the Mysis relicta group

Mysid crustaceans of the Mysis relicta group play central roles in many fresh- and brackish-water ecosystems both in northern Eurasia and North America. Yet, the recent division of the taxon into four sibling species by molecular criteria has largely remained unnoticed in ecological studies. We illustrate the morphometric differences among these species and the feasibility of their practical discrimination using multivariate analyses of 31 metric and meristic traits. The main patterns of size-independent variation identified in principal component analysis of individuals and in canonical variate analysis of populations corresponded to their assignment to the allozymically delineated species. The main variables contributing to discrimination described the spines or setae of the telson, uropods and maxillae, and the shape of the telson cleft. The subarctic sp. III was the phenetically most distinct from the others. The European stenohaline sp. I appeared intermediate between the North American freshwater sp. IV and the European euryhaline sp. II. In discriminant analyses between individual species pairs, 97-100 % correct identification was obtained using 3 -10 characters. The discriminant function for sp. I vs. sp. II, whose distributions overlap in northern Europe, was tested with independent material, and found to be a reliable means of species identification both at population level and at individual level in sympatric populations.

Regional controls on geomorphology, hydrology, and ecosystem integrity in the Orinoco Delta, Venezuela

Interacting river discharge, tidal oscillation, and tropical rainfall across the 22,000 km 2 Orinoco delta plain support diverse fresh and brackish water ecosystems. To develop environmental baseline information for this largely unpopulated region, we evaluate major coastal plain, shallow marine, and river systems of northeastern South America, which serves to identify principal sources and controls of water and sediment flow into, through, and out of the Orinoco Delta. The regional analysis includes a summary of the geology, hydrodynamics, sediment dynamics, and geomorphic characteristics of the Orinoco drainage basin, river, and delta system. Because the Amazon River is a major source of sediment deposited along the Orinoco coast, we summarize Amazon water and sediment input to the northeastern South American littoral zone. We investigate sediment dynamics and geomorphology of the Guiana coast, where marine processes and Holocene history are similar to the Orinoco coast. Major factors controlling Orinoco Delta water and sediment dynamics include the pronounced annual flood discharge; the uneven distribution of water and sediment discharge across the delta plain; discharge of large volumes of water with low sediment concentrations through the Rı́o Grande and Araguao distributaries; water and sediment dynamics associated with the Guayana littoral current along the northeastern South American coast; inflow of large volumes of Amazon sediment to the Orinoco coast; development of a fresh water plume seaward of Boca Grande; disruption of the Guayana Current by Trinidad, Boca de Serpientes, and Gulf of Paria; and the constriction at Boca de Serpientes.

Methane Emission from the Coastal Area in the Southern Baltic Sea

In the shallow coastal area of the brackish water ecosystem of the Baltic Sea, between the Islands of Rügen and Hiddensee (Southern Baltic, Germany), methane emission was continuously determined with floating measuring chambers and automatic sampling equipment. Data were collected during six measuring periods in two years (1995, 1996).The evaluation of more than 5700 measuring series demonstrated very strong seasonal and interannual variations of methane emission, with extremely high rates in the range between 24 and 104mg CH4m−2h−1in June/July 1995, and the lowest values in the range between 0·03 and 0·11mgCH4m−2h−1in October 1996. The highest single emission rate was 243mgCH4m−2h−1. Therefore this shore region represents, at least periodically, a hot spot for methane emission from a brackish water ecosystem into the atmosphere.The crucial controlling factor for the interannual and seasonal variations of methane emission and also for the small spatial differences was found to be the amount of organic matter in the sediment. This exerted a direct influence on methanogenesis and additionally indirect effects on oxygen dynamics and the relationships between methanogenesis and sulphate reduction.The significant correlation between methane emission and temperature in the water and sediment demonstrated that diurnal and long-term variations of emission rates during each season were mainly regulated by temperature. Only at low emission rates did other, indirect ecological factors become more important in controlling methane emission.

Habitats and Distribution Patterns of Marine Luminous Bacteria in the Western Baltic Sea

AbstractNumbers of luminous bacteria were counted at three stations of the brackish water ecosystem of the western Baltic Sea from July 1985 to July 1986. Additional samples were taken during three cruises from stations at the North Atlantic Ocean, the Norwegian Sea and adjacent marine areas. — In Kiel Bight (western Baltic) values varied between 0 and 68,000 luminous cfu 1−1. With exception of the coastal station a distinct seasonal distribution pattern was shown in a water depth of 20 m: high numbers found in summer were opposed to low numbers in winter, the peaks being rather high in comparison to those of other areas. Statistical analysis showed that the results of 20 m were significantly different from those of 0 and 10 m depth; however, there was no correlation with temperature and salinity. Taxonomic studies revealed that the population consisted primarily of the genus Photobacterium. — The optimum of salinity was not a brackish but a marine one and was about 30% for the majority of the strains tested. A smaller number of strains grew best at a salinity between 10 and 15%. Optima of temperature ranged from 15 to 20 °C for most of the test strains. — Taxonomic analysis was also performed with luminous strains from marine areas adjacent to the western Baltic Sea, Photobacterium being the dominant genus here, too. Luminous bacteria were also enriched from the external surface and the gut contents of whitings (Merlangius merlangus) and cods (Gadus morhua). A model is proposed which explains the distribution pattern found. According to this, the gut‐dwelling luminous bacteria are transported by their hosts from the North Sea into the western Baltic Sea. Here they are released into the environment, thus inhabiting another niche.

The Effects of Salinity on Biological Metabolism in Brackish Water Ecosystems

The Effects of Salinity on Biological Metabolism in Brackish Water Ecosystems

Sulfate Reducing and Methane Fermentation in a Brackish Water Ecosystem

Sulfate Reducing and Methane Fermentation in a Brackish Water Ecosystem

Fate and effects of pulp mill chlorophenolic 4,5,6-trichloroguaiacol in a model brackish water ecosystem

The fate and effects of the pulp mill effluent compound 4,5,6-trichloroguaiacol (TCG) were tested over 16 months on a model Baltic Sea littoral zone using a Fucus vesiculosus-based mesoscale model ecosystem. Bioaccumulation of TCG and metabolites from water ranged from 50 times for algae up to 700 times for invertebrates and fish, the factor increasing with trophic level. Algae contained chloroguaiacols, chlorocatechols and chloroveratroles and exhibited no major toxic effect. Fucus colonization appeared to be hindered by filamentous algae which covered surfaces otherwise available for new colonization. This unrestricted filamentous algal growth was probably a result of reduced grazing by herbivores, which in turn was apparently caused by reproduction failure in herbivorous crustaceans. Sediment-dwelling organisms appeared less affected than invertebrates in the algal habitat, possibly because of reduced bioavailability of toxic compounds due to binding to sediment particles. TCG and metabolites in the sediment were dominated by catechols; no veratroles were found. Only in the largest size class of sticklebacks was there a dose-related reduction in mean weight. Only 0.5% of the TCG added was recovered in the system after 16 months. Of this, 99% was associated with the sediment. The remainder was divided equally between algae and fauna. The role of algae and sediment in the Baltic Sea littoral zone is therefore paramount to the ultimate fate and effects of such compounds on invertebrates and fish.

Production and respiration of overall plankton and ultraplankton communities at the entrance to the Gulf of Finland in the Baltic Sea

Primary productivity and respiration of the overall plankton community and of ultraplankton (organisms passing through a 3-μm Nuclepore filter) were studied at the entrance to the Gulf of Finland during the growth season in 1982. Data of the respiration measurements from previous years are also presented. During the development of a diatom spring bloom, the algal component could be successfully separated from the bacterial component by size fractionation with a 3-μm Nuclepore filter and thus the “algal” respiration could be approximated, being on the order of 10 to 20% of the gross production. After the phytoplankton spring maximum, bacteria played an important role in mediating the energy flow from phytoplankton exudates to higher trophic levels. Maximum values of 1 230 and 740 mg O2 m-2 d-1 were recorded for overall and for ultraplankton respiration, respectively, during late July. High productivity values coupled with low phytoplankton biomass and low inorganic nutrient values were also recorded in late July, indicating effective nutrient regeneration and rapid turnover of the plankton community. During late summer, a considerable fraction (over 30%) of phytoplankton production was released as exudates, suggesting that much of the energy is channeled to higher trophic levels via bacterial pathways rather than by direct herbivorous grazing during this season. The summer development of phytoplankton community structure and functioning is strongly controlled by hydrographic conditions, i.e. by nutrient inputs via upwelling and by water temperature. A carbon budget for late summer indicated that bacteria may contribute only up to 50% of the overall respiration of the plankton community, which suggests that heterotrophs other than bacteria play an important role in nutrient regeneration. The present study stresses the importance of energy flow via the phytoplankton exudatebacteria-micrograzer pathway in relatively oligotrophic, brackish water ecosystems.