Brackish-water Fauna Research Articles

Роль солоноватоводной фауны и состояние биоресурса экосистемы гипергалинного озера Кулундинское в фазе трансгрессии (Алтайский край)

The results of ecological monitoring of the hypergaline lake Kulundinskoye of the Altai Territory in the period 2021-2022 are presented. The research was carried out in the form of a comprehensive study of abiotic factors of the reservoir (climatic features of the lake, temperature regime, salinity of water), biological factors (species composition of brackish-water zooplankton, its abundance), production and structural indicators of the gill-legged crustacean Artemia Leach, 1819. Desalination of water during the transgressive period of water content caused successional speciation processes. There was a change of the gill-legged crustacean as a dominant and monovid to a complex of brackish-water fauna. The artemia population developed under the influence of unfavorable salinity of water with a fluctuation in the lake from 1.9 (April) to 99.0 mg/dm3.
 The influence of the transgressive phase of water content on the biota and the extraction (catch) of a biological resource - artemia (at the stage of cysts), as well as the importance of the formation of their commercial accumulations of abiotic environmental factors, is shown. Studies have shown that the prevailing combination of factors during the transgression period – tense climatic conditions, low salinity of water (less than 100 mg/dm3), low number of artemia crustaceans, was the absence of commercial accumulations of biological resources.

Holocene development of Brabrand Fjord, eastern Jylland, Denmark.

The Brabrand Sø area west of Aarhus in eastern Jylland, Denmark, was deglaciated about 18 000 to 17 000 years ago. Coring in the present-day lake area revealed Early Holocene stream deposits overlain by marine deposits. The area was transgressed by the sea at c. 8500 cal. years BP and a 12 km long, narrow fjord was formed. In the beginning, the fjord housed a species-poor marine or brackish-water fauna with molluscs Hydrobia sp. (mudsnail), Littorina littorea (winkle), Mytilus edulis (blue mussel) and Cerastoderma sp. (cockle). This phase was followed by a phase during which the fjord housed a species-rich fauna that included Ostrea edulis (European flat oyster) and Ruditapes decussatus (palourde clam). During this phase the salinity and summer water temperatures were higher than in present day Aarhus Bugt and we also see evidence for strong bottom currents. This phase was probably characterised by a fairly large tidal amplitude. Two radiocarbon ages of O. edulis shells of c. 6250 and 6700 cal. years BP indicate that such conditions peaked during the period of the Ertebølle culture. The high-salinity phase was followed by a phase with a more species-poor fauna, this phase was also characterised by a high sedimentation rate – a feature seen in other fjords in the region. We suggest that the shift could be due to a decrease in tidal amplitude. Brabrand Fjord was eventually transformed into a lake due to land uplift and closure of the connection to Aarhus Bugt due to longshore sediment transport but the timing of the transition from fjord to lake is still unknown.

A new genus and species of Hydrobiidae Stimpson, 1865 (Caenogastropoda, Truncatelloidea) from Peloponnese, Greece.

Minute caenogastropod brackish-water gastropods, formerly classified as Hydrobia, are important elements of the brackish-water fauna and were objects of intensive study for many years. Until now, five genera have been distinguished, most of them represented by a number of species, but rather indistinguishable without molecular data (cytochrome oxidase subunit I – COI). In the eastern Mediterranean region, they are still poorly studied. In this paper, we present a new species of “Hydrobia” from the brackish Moustos spring, Arkadia, eastern Peloponnese, Greece. The shell, protoconch, radula, female reproductive organs, and penis are described and illustrated, together with the molecular (COI) relationships with other hydrobiids. All data confirm that these snails represent a distinct taxon, which must be classified as a new species belonging to a new genus. The formal descriptions are given. The closest, sister taxon is Salenthydrobia Wilke, 2003. The molecularly estimated time of divergence, 5.75 ± 0.49 Mya, coincides with 5.33 Mya, which is the time of the Oligocene flooding that terminated the Messinian salinity crisis. During the latter period, brackish “Lago-Mare” habitats were most probably suitable for the last common ancestor of Salenthydrobia and the newly described genus. Later, the Pliocene flooding isolated the Apennine and Peloponnese populations, promoting speciation.

High-resolution Sr-isotopic evolution of Black Sea water during the Holocene: Implications for reconnection with the global ocean

The 10 m-thick Holocene succession at core site M02-45 (41°41.17′N, 28°19.08′E, −69 m water depth) has key advantages for investigation of the Sr-isotopic evolution of the Holocene Black Sea. Earlier studies have focussed on thinner successions and coquinas. At the M02-45 site (augmented by nearby core M05-03P), 87Sr/86Sr determinations on mollusc shells extracted at mostly 10–20 cm depth increments provide a temporal resolution mostly <200 years in sediment older than ~5500 cal yr BP, and ~20–25 years for the early Holocene reconnection between the Black Sea (formerly the Neoeuxine Lake) and the global ocean. Isotopic measurements are in stratigraphic order, so temporal trends are unambiguous. Measurements were made using a Neptune multi-collector inductively coupled plasma mass spectrometer (MC-ICPMS) and have 1σ uncertainties of ~ ±0.000015. There are four stages of 87Sr/86Sr increase and salination associated with the reconnection. From 12,145–9580 cal yr BP (stage A), before first Mediterranean inflow, the Sr-isotopic ratio varied from 0.708847–0.708881. Modelling suggests that the Sr concentration in the Neoeuxine Lake might have been several times higher than modern river values because of evaporative concentration. For ~100 years immediately before reconnection (9580–9490 cal yr BP, stage B), 87Sr/86Sr values dropped to their lowest levels: 0.708841–0.708843. Abruptly (in geological terms), 87Sr/86Sr then began to climb starting 9465–9490 cal yr BP and reached a quasi-steady-state ‘plateau’ with ratios ~0.708965 by ~9380 cal yr BP (stage C). The sharp 87Sr/86Sr increase marks the first significant intrusion of saline water into a previously isolated Neoeuxine Lake. The quasi-steady-state condition lasted 350–400 years. Subsequently, starting ~8985 cal yr BP and proceeding to the present day, there was a step-wise rise of 87Sr/86Sr to modern levels (stage D), during which a salinity threshold was passed that allowed widespread replacement of brackish-water faunas by Mediterranean species. Modelling suggests that the lake/sea level likely did not, and could not, rise from −120 m to −30 m between 9490 and 9380 cal yr BP unless (a) the Sr concentration in the pre-reconnection Neoeuxine Lake was 3–4 times higher than today, or (b) the water column was strongly stratified during first entry of saline water. The second alternative is very unlikely because of seasonal vertical mixing (downwelling/upwelling) in what was then a rather homogeneous temperate lake. Catastrophic flooding of a lowstand lake would require an average discharge through the Strait of Bosphorus of ~9500 m3 s−1, whereas saline entry of Mediterranean water as an underflow into an already high lake could reproduce the first stage of 87Sr/86Sr increase with an average discharge as low as ~2200 m3 s−1. Because the M02-45 site is ~50 m above the late Pleistocene lowstand shoreline and contains sub-wavebase sediments with 87Sr/86Sr values that record the first entry of saline water into the Neoeuxine Lake, the surface of the lake must have been significantly higher than −70 m at the time of the reconnection. Two prominent ‘plateaux’ which punctuate the long-term 87Sr/86Sr increase are attributed to decadal to centennial periods of increased discharge from European rivers, creating a positive hydrological balance and effectively blocking or seriously impeding saline-water advance up the Strait of Bosphorus toward the Black Sea.

Sedimentary architecture and depositional controls of a Pliocene river-dominated delta in the semi-isolated Dacian Basin, Black Sea

Sedimentological facies models for (semi-)isolated basins are less well developed than those for marine environments, but are critical for our understanding of both present-day and ancient deltaic sediment records in restricted depositional environments. This study considers an 835 m thick sedimentary succession of mid-Pliocene age, which accumulated in the Dacian Basin, a former embayment of the Black Sea. Detailed sedimentological and palaeontological analyses reveal a regression from distal prodelta deposits with brackish water faunas to delta-top deposits with freshwater faunas. Sediments contain frequent hyperpycnal plumes and an enrichment in terrestrial organic material, ichnofossils and in situ brackish and freshwater faunas. Deltaic progradation created thin, sharply-based sand bodies formed by multiple terminal distributary channels, covering a wide depositional area. The system experienced frequent delta-lobe switching, resulting in numerous thin parasequences. Parasequences are overlain by erosive reddish oxidized sand beds, enriched in broken, abraded brackish and freshwater shells. These beds were formed after sediment starvation, on top of abandoned delta lobes during each flooding event. A robust magnetostratigraphic time frame allowed for comparison between the observed sedimentary cyclicity and the amplitude and frequency of astronomical forcing cycles. Our results indicate that parasequence frequencies are significantly higher than the number of time equivalent astronomical cycles. This suggests that delta-lobe switching was due to autogenic processes. We consider the observed facies architecture typical for a delta prograding on a low-gradient slope into a shallow, brackish, protected, semi-isolated basin. Furthermore, in the absence of significant wave and tidal influence, sediment progradation in such a protected depositional setting shaped a delta, strongly river-dominated.

Checklist of ichthyofauna of Madampa-Lake sanctuary in Ambalangoda, Southwest Sri Lanka

Coastal lagoons provide unique services for many kinds of aquatic and semi aquatic organisms. Madampa-Lake is a brackish water lagoon containing a dynamic mangrove ecosystem complex with extraordinary genetic diversity, which is located in the southwest coastal belt near Ambalangoda city, Galle District. Very little literature is available on the Madampa-Lake’s fish and almost none of them have been published. A preliminary assessment on vertebrates and butterfly fauna was carried out during April 2009 to August 2010, and this article covers ichthyofaunal phase of the survey. Ichthyofauna diversity of Madampa is a combination of salt water (sea), brackish water and fresh water fish and their different life stages. During this study, a total of 49 species (33 families) were recorded, and this included two endemics and five alien species. Keywords. Brackish-water fauna, conservation, lagoons, mangrove-ecosystem, Sustainable uses.

A new Paratethyan genus of the ostracod subfamily Loxoconchinae (Podocopida, Cytheroidea)

A new ostracod genus established in a Loxoconchinae fauna from the Eastern Paratethys, with two species known from the Pliocene–post-Pliocene and Recent of the Caspian Sea and Dnieper–Bug estuary of the Black Sea Basin is described. Comparative morphological analysis of four Loxoconchinae genera from a brackish-water fauna of the Paratethyan basins is performed and the trends in morphological evolution of their hinge structures are revealed.

Geological setting, sedimentology and biota of the estuarine late Oligocene Pomahaka Formation, New Zealand

ABSTRACTPomahaka Formation, a late Oligocene succession of interbedded mudstone, lignite, shell beds and thin sands, was studied in small exposures along the Pomahaka River near Tapanui, Otago and in four adjacent sections in Waikoikoi Creek where about 17 × 0.25–4.0 m thick facies cycles were exposed. At the base of an ‘ideal’ cycle, thinly laminated sandy mudstone overlying lignite of the previous cycle records transgressive flooding of forest swamp by fresh or estuarine waters. Laminated shelly mudstone containing venerid bivalves (Hinemoana acuminata) forming the middle of several cycles represents maximum marine flooding. Above this, trough cross-stratified beds and sand with mud flaser laminae record progradation of distributary bars and/or intertidal sands. Finally, deposition of root-burrowed mudstone and lignite mark the re-establishment of swamp forest. Predominantly muddy sediment texture, the association of lignite, distinctive fresh- and brackish-water faunas and thin depositional cycles indicate a microtidal estuarine paleo-environment in southern Zealandia during late Oligocene time.

Migration and isolation during the turbulent Ponto-Caspian Pleistocene create high diversity in the crustacean Paramysislacustris.

The Ponto-Caspian brackish-water fauna inhabits estuaries and rivers of the Black, Azov and Caspian seas and is fragmented by higher salinity waters and a major interbasin watershed. The fauna is known for the high levels of endemism, complex zoogeographic histories, and as a recent source of successful invasive species. It remains debated whether the Black and Azov Sea brackish-water populations survived unfavourable Pleistocene conditions in multiple separate refugia or whether the two seas were (repeatedly) recolonized from the Caspian. Using microsatellite and mtDNA markers, we demonstrate deep among- and within-basin subdivisions in a widespread Ponto-Caspian mysid crustacean Paramysislacustris. Five genetic clusters were identified, but their relationships did not reflect the geography of the region. The Azov cluster was the most distinct (4-5% COI divergence), despite its geographic position in the corridor between Black and Caspian seas, and may represent a new species. In the northern Black Sea area, the Dnieper cluster was closer to the Caspian cluster than to the neighbouring Danube-Dniester-Bug populations, suggesting separate colonizations of the Black Sea. Overall, the data implied a predominant gene flow from the east to the Black Sea and highlight the importance of Caspian Sea transgressions in facilitating dispersal. Yet, the presence of distinct lineages in the Black Sea points to the persistence of isolated refugial populations that have gained diagnostic differences under presumably high mutation rates and large population sizes. The unfavourable Pleistocene periods in the Black Sea therefore appear to have promoted diversification of the brackish-water lineages, rather than extirpated them.

Swimming reptiles make their mark in the Early Triassic: Delayed ecologic recovery increased the preservation potential of vertebrate swim tracks

Fossil tetrapod swim tracks have been reported from deposits throughout the world, ranging in age from the Carboniferous (Mississippian) to the Neogene (Pleistocene). A normalized analysis of these occurrences demonstrates that lower Triassic strata contain an anomalously high number of occurrences. Lower Triassic swim tracks also tend to be better preserved, showing exceptionally detailed features such as scale striae and crescent-shaped claw margins. Preservation of these features required a firm and semicohesive substrate in order to maintain track detail before and after burial. Swim-track localities from the lower Triassic Moenkopi Formation in Utah (USA) are characterized by sedimentary and trace fossil features that demonstrate the widespread development and persistence of firmground substrates in a large delta plain complex. Within this delta, complex low-diversity invertebrate trace fossil assemblages consist of locally high densities of diminutive, millimeter-scale traces characteristic of stressed brackish-water faunas. We suggest that the depauperate infauna characteristic of such environments was repressed due to delayed biotic recovery following the end-Permian mass extinction, resulting in extremely low intensities of bioturbation. Lack of biogenic mixing promoted semiconsolidation of dewatered mud substrates and the widespread production and persistence of firmgrounds capable of recording and maintaining swim tracks. Thus a combination of factors, unique to the Early Triassic, increased the preservation potential of detailed swim tracks: (1) depositional environments that promoted the production of firmground substrates, (2) delayed ecologic recovery resulting in the lack of well-bioturbated sediment, and (3) the swimming behavior of various Early Triassic tetrapods.

Harpacticoida (Copepoda) fauna and the taxocenes structure of brackish lagoons and estuaries of the Russian far east

On the basis of original data and literature sources, the species composition of Harpacticoida (Copepoda) in the plankton of the brackish waters of four Far Eastern regions was described: Khabarovsk krai, Sakhalin Island, Kamchatka Peninsula, and the Commander Islands. The compiled list includes 32 harpacticoid species of 22 genera and 10 families. The representatives of the typical brackish families Canthocamptidae and Ectinosomatidae account for about one-third of the total. Six of the species are new to science: 4 species of Halectinosoma, Amphiascus sp. 1, and Schizopera sp. 1. Cosmopolitan species constitute the major portion of the fauna (38% of the total number), while a smaller proportion is typical of endemics (25%), as well as species with the arctic (12%), tropical (9%), and North American (9%) types of areas. There are 17 types of harpacticoid taxocenes of the observed water bodies. Also, the influence of the salinity and temperature on these species complexes was characterized. The hypotheses about the cosmopolitanism of the brackish water fauna and the intrazonality of the estuarine harpacticoid taxocenes structure were tested. It is shown that the structure of the genera dominance in the taxocenes allocated for the temperature latitudes of the Far East demonstrates significant similarity with the arctic and tropical regions.

Middle Ottnangian (late Burdigalian) mollusks from the Rott Valley (SE Germany): the ultimate marine fauna of the Western Paratethys

The Bivalvia and Gastropoda from the Upper Marine Molasse deposits of the lower Rott Valley (North Alpine Foreland Basin, Lower Bavaria, SE Germany) comprise the first mollusk fauna of middle Ottnangian age (ca 17.5 Ma) to be documented in detail. Altogether, the assemblages from Brombach, Kainerding and Anzenkirchen yielded 27 species of Bivalvia and 9 species of Gastropoda. The bivalve species Spisula brombachensis n. sp. is described as new to science, and Aequipecten camaretensis is first reported from the Ottnangian of the North Alpine Foreland Basin. Furthermore, the well-preserved material allowed for the taxonomic revision of the Ottnangian index fossil Pecten herrmannseni. The bivalve community is dominated by suspension feeders, mostly shallow, soft bottom dwellers (Glycymeris, Anadara) and cementing epifauna (Ostrea). Gastropods almost exclusively comprise carnivorous browsers and predators. The parautochthonous assemblages are indicative of normal marine, well-oxygenized sandy-silty shoals at a water depth of presumably less than 20 m. Except for the presence of a single estuarine Crassostrea, the middle Ottnangian fauna is not indicative of reduced salinities. Consequently, the paleoenvironmental turnover to the brackish-water fauna of the directly overlying upper Ottnangian deposits of the Rzehakia Lake was abrupt. Glycymeris–Anadara–Ostrea communities similar to the one recorded from the Rott Valley are widespread in European seas and beyond during the Neogene and Quaternary.

Biotic and abiotic response to palaeoenvironmental changes at Lake Pannons' western margin (Central Europe, Late Miocene)

A multidisciplinary study was performed on a c. 30m thick, limnic–deltaic sequence in the Styrian Basin (Austria). Geophysical (gamma ray activity, rock magnetism), geochemical (organic carbon, sulphur) and sedimentological observations were combined with palaeontological information (mainly ostracods). On this base, several ecological factors were deduced (terrigenous influx, salinity, water depth and oxygenation). Based on integrated stratigraphy as well as on palaeomagnetic results the whole section is set to Chron C5r.2r−1n (11.308–11.263Ma) and covers a period of less than 45kyr. In addition to the long-term record, we analysed short-term changes by high-resolution sampling (5mm sample interval; ostracods, magnetic susceptibility). This ~2.3m-thick interval spans in total <3500yr with an individual sample resolution of a few years only. The combination of these data permit the description of the palaeoenvironmental evolution of the section in detail: at the base of the section, the development of a conifer swamp on the lakeside of Lake Pannon is documented. This almost freshwater swamp existed for some centuries before it became extinct within a few decades due to a rise of the water-table. The drowning is related to a transgression of Lake Pannon, which triggered the establishment of a brackish-water fauna as well as greigite formation in the lake sediments. In general, the ongoing transgression favoured benthic life due to increased salinity (up to mesohaline conditions). The high-resolution ostracod and magnetic susceptibility record reflect short-term fluctuations in bottom-water ventilation. These oscillations probably range in the order of centuries and decades and are possibly related to climatic shifts. Later, the successive deepening of the lake resulted in a significant faunal turnover. A meromictic system with a well-established, oxygen-depleted hypolimnion developed. Finally, the limnic phase was replaced by a prograding deltaic system, where the amplified input of coarse-grained material and freshwater also affected benthic life. Periodic changes in clay (illite) content were detected by the gamma ray-log throughout the entire section. The observed cycles (5–12kyr) of the gamma ray-log may reflect a super-ordinate modulation of the sedimentary record by climatically forced changes in precipitation or run-off.

The Effect Of Textile Mill Effluent On Two Brachish Fauna Species (Oreochromis Niloticus And Palaemonetes Africanus) In Ibeshe River Lagos State

Acute toxicity of textile mill effluent to two brackish fauna species, Oreochromis niloticus (finfish) and Paleamonetes africanus. (Shrimp) fingerlings were assessed in a static renewable bioassay for 96h to determine median lethal concentrations (LC50). Seven different graded concentrations were prepared as 0.5, 1.0, 2.0, 4.0, 6.0, 8.0 and 2, 4, 6, 8, 10, 12mg L-1 for Oreochromis niloticus and Paleamonetes africanus fingerlings, respectively. However, a control experiment (0mgL-1) was set up accordingly. The 96h (LC50) value computed on logarithm were 1.21 and 5.11mgL-1 for Oreochromis niloticus and Paleamonetes africanus fingerlings, respectively. The median LC50 were 24, 48, 72 and 96h for 4.83, 2.01, 1.38 and 1.20 mgL-1 on Oreochromis niloticus fingerlings, exposed to different concentration textile mill effluent. However, median LC50 were 24, 48, 72 and 96h for 9.02, 7.82, 6.76, and 5.09 mgL-1 on Paleamonetes africanus fingerlings, exposed to different concentrations of textile mill effluent. The fingerlings of tilapia and shrimps exposed to various concentration of effluent showed uncoordinated behaviour, increase in their movements, ventilation, spiral swimming, sideway swimming, effort to swallow air from the surface for the tilapia fingerlings while shrimp fingerlings showed backward swimming and static swimming for few minutes. Mortality was recorded early in Oreochromis niloticus fingerlings at 0.5mgL-1 during a 24h exposure to the textile mill effluent while for the Paleamonetes africanus, mortality was recorded at 6mg L-1 for 24h exposure to the textile mill effluent physico-chemical assessment of the textile mill effluent were given as: Total Suspended Solids TSS (400-mgL-1) Biological Oxygen Demand BOD (362.6-397.1 mgL-1, Detergent (40.2-49.9 mgL-1) Alkalinity (575-1225 mgL-1), Oil and grease 28.3-31.2 mgL-1), Dissolved Oxygen DO (3.30-3.90 mgL-1). These were higher than the FEPA limit for effluent discharge. However, physico chemical analysis revealed low, species diversity of aquatic fauna in Ibeshe River. This suggests that effluent discharge into the river is hig7hly toxic to brackish water fauna species. Keywords: Toxicity, effluent, Oreochromis niloticus, Paleamonetes africanus, physico-chemical parameters. JOAFSS Vol. 4 (1) 2006: pp. 194-203

Phylogeny of Paramysis (Crustacea: Mysida) and the origin of Ponto-Caspian endemic diversity: Resolving power from nuclear protein-coding genes

The Ponto-Caspian (Black and Caspian seas) brackish-water fauna represents a special case of the endemic diversification in world’s ancient lakes; it also involves a hotspot of continental diversity in the predominantly marine mysid crustaceans. We explored the origins and history of the mysid diversification in a phylogenetic analysis of some 20 endemic Ponto-Caspian species mainly of the genus Paramysis and their marine congeners, using sequences of two nuclear protein-coding genes, two nuclear rRNA genes, the mitochondrial COI gene and morphological data. A nearly completely resolved phylogeny was recovered, with no indication of rapid diversification bursts. Deep divergences were found among the main endemic clades, attesting to a long independent faunal history in the continental Paratethys waters. The current marine Paramysis species make a monophyletic cluster secondarily derived from the continental Paratethyan (Ponto-Caspian) Paramysis ancestors. The good phylogenetic resolution was mainly due to the two nuclear protein-coding genes, opsin and EPRS, here for the first time applied to peracarid systematics. In contrast, ‘conventional’ mtDNA and nuclear rRNA genes provided poor topological resolution and weak congruence of divergence rates. The two nuclear protein-coding genes had more congruent rates of evolution, and were about 10–15 times slower than the mitochondrial COI gene.

Macroinvertebrate communities in sediment and plants in coastal Mediterranean water bodies (Central Iberian Peninsula).

Sediment and plant-associated macroinvertebrates were sampled in six shallow water bodies along the central part of the coast of Mediterranean Spain. The size of ponds, salinity and hydroperiod were highly variable. Seventy-one taxa were recorded, some of them were endemic or uncommon species, evidencing the important contribution of these ponds to biodiversity. Crustaceans and gastropods of biogeographical interest were found in the most primeval site. Correspondence analysis showed that macroinvertebrate assemblages responded to environmental variables such as salinity, temporality and eutrophication. The brackish water fauna was dominated by crustaceans, while oligochaeta and insect larvae were abundant in freshwater conditions. Oligochaetes were abundant at localities with high trophic level, whereas localities with semi-permanent waters were dominated by chironomids. The density of macroinvertebrates was clearly related with trophic state but we did not find significant relationships between density and salinity or water permanence. For plant associated samples our results showed negative relationships between species richness and temporality or salinity, contrary to sediment samples, where the Oligochaeta/Chironomidae ratio in sediments and the percentage of sensitive taxa (Ephemeroptera, Odonata, Trichoptera) were useful indices, and were dependent on pond typology. This study emphasizes the broad ecological variety of ponds found in these wetlands and their importance for biodiversity. Some ponds act as permanent biodiversity reservoirs in fluctuant marshes with seasonal dryness, calling for more attention on their ecological relevance for management strategies.

Macroinvertebrate communities in sediment and plants in coastal Mediterranean water bodies (Central Iberian Peninsula).

Sediment and plant-associated macroinvertebrates were sampled in six shallow water bodies along the central part of the coast of Mediterranean Spain. The size of ponds, salinity and hydroperiod were highly variable. Seventy-one taxa were recorded, some of them were endemic or uncommon species, evidencing the important contribution of these ponds to biodiversity. Crustaceans and gastropods of biogeographical interest were found in the most primeval site. Correspondence analysis showed that macroinvertebrate assemblages responded to environmental variables such as salinity, temporality and eutrophication. The brackish water fauna was dominated by crustaceans, while oligochaeta and insect larvae were abundant in freshwater conditions. Oligochaetes were abundant at localities with high trophic level, whereas localities with semi-permanent waters were dominated by chironomids. The density of macroinvertebrates was clearly related with trophic state but we did not find significant relationships between density and salinity or water permanence. For plant associated samples our results showed negative relationships between species richness and temporality or salinity, contrary to sediment samples, where the Oligochaeta/Chironomidae ratio in sediments and the percentage of sensitive taxa (Ephemeroptera, Odonata, Trichoptera) were useful indices, and were dependent on pond typology. This study emphasizes the broad ecological variety of ponds found in these wetlands and their importance for biodiversity. Some ponds act as permanent biodiversity reservoirs in fluctuant marshes with seasonal dryness, calling for more attention on their ecological relevance for management strategies.

Ecologic and taxonomic diversification in the Mesozoic brackish-water bivalve faunas in Japan, with emphasis on infaunalization of heterodonts

Mesozoic brackish-water bivalve faunas in Japan diversified in three steps: at the beginning of the Early Jurassic, Early and Late Cretaceous. The Hettangian Niranohama Fauna in northeastern Honshu represents the establishment of a heterodont-dominated brackish-water fauna that persisted until the early Late Cretaceous. No similar composition is known from the Triassic. The infauna consists mostly of non-siphonate and some short-siphonate heterodonts, while the epifauna is represented by diverse pteriomorphian families. In the Early Cretaceous Tetori Group in central Honshu, the long-siphonate heterodonts Tetoria (Corbiculidae) and the semi-infaunal soft-bottom oyster Crassostrea appeared. The evolutionary diversification of the latter, known as the most important element of modern brackish-water faunas, may thus originate at that time. In the early Late Cretaceous (Cenomanian) of the Goshoura and Mifune Groups in west Kyushu, several euryhaline deep-burrowing heterodont families, such as Veneridae and Tellinidae, further diversified in the brackish and marine environments. The Late Cretaceous is characterized by massive shell biolithic beds in which large Crassostrea species are common, a feature common for Cenozoic brackish-water faunas. The long-term changes in the composition of the brackish-water faunas in Japan represents thus an evolutionary record, irrespective of the severe physiological and environmental conditions imposed on the highly conservative nature of the fauna.

First European record of the invasive brackish water clam Rangia cuneata (G.B. Sowerby I, 1831) (Mollusca: Bivalvia)

* Corresponding author Abstract A population of Rangia cuneata (G.B. Sowerby I, 1831), an estuarine bivalve, has been recorded in the harbour of Antwerp, Belgium. This species is new to the European brackish water fauna. After initially finding only a few small individuals in August 2005, R. cuneata was encountered frequently in the pipes of the cooling water system of an industrial plant from February 2006 onwards. Before this present record, R. cuneata was only known from the Gulf of Mexico and the Atlantic coast of North America.

Messinian crisis: What happened around the northeastern Aegean?

The effects of the severing of the Atlantic–Mediterranean connection during the ∼400,000-year Messinian event are also observed around the northern Aegean. During this time, a sea of brackish-water character developed between Paratethys in the north and the Mediterranean in the south. This sea is named here “Egemar.” This basin was principally fed by surrounding rivers and by Paratethyan waters that entered Egemar via a connection through the Sea of Marmara, which was then a bay of the Paratethys. The sedimentary sequence deposited in Egemar is principally composed of limestones containing brackish-water fauna (Paratethyan). However, there are some intercalations containing Mediterranean species. Five intercalations of Mediterranean character are found within the sedimentary sequence of Egemar indicating the re-establishment of an Atlantic–Mediterranean connection from time to time and, thus, replenishment of marine waters. The Turolian is represented by continental clastics which interdigitate with the brackish-water cycles, implying a number of regressions. Egemar eventually became part of the eastern Mediterranean due to a major transgression during the early Pliocene.