Brackish Water Taxa Research Articles

Long-term supratidal rockpool invertebrate community, Discovery Bay, Jamaica.

The rockpool cluster offers unique characteristics making it a model system for general questions in ecology: (1) all rockpools share biotic history (any species can reach any rockpool); (2) they form a strong gradient of conditions from benign to harsh; (3) 1-day sampling across all rockpools ensures census consistency; (4) rockpools respond to changing conditions within a short (days) time frame; (5) they are easy to manipulate (note: the data are from an unmanipulated rockpool subset), and (6) they may act as a single metacommunity that exhibits consistent species distribution patterns on a broader scale (unpublished). Consequently, the rockpools continue generating insights, with the first publications in 1996. The data represent an intensive rockpool metacommunity monitoring project, making them of considerable value to our understanding of tropical coastal metacommunity dynamics and general ecological processes. The dataset covers surveys of invertebrate fauna in 49, primarily supratidal, rockpools on a fossil coral reef over 25 years. All rockpools occur within a 73 × 47 m array of rocks at a distance of less than 2 m from the nearest neighbor. About 200 other rockpools occur on the same area. They are in a sheltered bay (Discovery Bay, Jamaica) between 0 and 5 m from the ocean. Typically, rockpools are 5-30 cm deep and 40 cm across on average, with elevation from a few centimeters to 300 cm above sea level. Rockpools may drain excess water from precipitation or waves into other rockpools, which allows organisms to disperse passively downstream. Of the 49 rockpools in the survey, 35 are subject to occasional drying up, while the others appear permanent. Most collections (1989-2004) were annual censuses of invertebrate populations, exceeding a total of 475,000 invertebrates counted, with only minor record gaps. In all cases, species level taxonomic information consists of detailed photographs. In some cases, notes are included with the taxonomic data where species identification could not be matched to information available in the literature. Samples from 2005 to 2019 still require organism identification. Abiotic parameters were measured the day before biotic sampling took place as the process of biotic sampling can impact abiotic parameters through stirring, oxygenation and filtering (temperature, pH, turbidity, dissolved oxygen, light intensity, salinity, alkalinity, and nutrients). The cumulative richness in the metacommunity consist of 78 freshwater, marine, and brackish water taxa, with a mean richness per rockpool of 5.5 distinct species. Regarding taxonomic makeup, ostracods dominated in both diversity and number, followed by copepods, and insects. There are no copyright restrictions on the data set; please cite this data paper when using these data in publications.

Effects of the tide on the temporal and spatial physicochemical structure of the Kienké river estuary (South Atlantic Coast of Cameroon, Kribi) and its phytoplankton

The present work aimed to understand the physicochemical and phytoplanktonic structure of the Kienke estuary water in the urban area of Kribi town in relation to human activities and fluvial or oceanic influences. Field investigations and laboratory work were devoted to the sampling and measurement of some physicochemical and biological parameters, specific treatments and classical statistics (descriptive, multidimensional) of variables. Estuary water is characterised by an instability and spatiotemporal variations in its physicochemical parameters. The most sensitive parameters are as follows: a temperature ranging between 22.6°C and 31°C under the influence of atmospheric variations, electrical conductivity and salinity that are relatively high (0.22 < C. E < 49.70 mS cm-1; avg =16.56 mS cm-1; 0 < Sal < 29.32 PSU; avg = 11.51 PSU), and a pH that is overall acidic to basic (6 < pH < 8.86; avg = 7.75 ± 0.82). The nutrients variation (ammonium, nitrite, nitrate and orthophosphate) is very low in space and time, with a longitudinal distribution controlled by tidal flows, river flows and the biological pump. For the 64 samples collected, 167 phytoplankton taxa were identified. The most abundant (36.36%) were Chrysophyta Division, followed by Chlorophyta. Species richness is marked by brackish water taxa. According to this structure and the combination of both gradients, mineratilisation and organic matter enrichment is of a physicochemical typology, and the biotypology is hydrotypologically dependent.

Tidal effects on phytoplankton assemblages in a near‐pristine estuary: a trait‐based approach for the case of a shallow tropical ecosystem in Brazil

AbstractThe study of near‐pristine estuaries can be used as a tool for mitigation projects of harmful effects in anthropogenic eutrophic systems, since one can analyze the effect of temporal and spatial variations generated mainly by natural forces. Phytoplankton taxonomy has been used as a classical indicator to assess changes in transitional water communities, however alternative methods based on morphological, behavioral and physiological traits offer the opportunity to compare sites or moments with different taxonomic compositions. Our goal, in this context, is to evaluate phytoplankton community short‐term and seasonal variability in a near‐pristine estuary, Barra Grande estuary (Ilha Grande, RJ, Brazil), through species functional traits and thus community functional diversity. Samplings were carried out in a mooring in complete tidal cycles, seasonally during 2012. Our results showed a diverse phytoplankton community with 38 frequent and abundant taxa, marked by density variation (1.2 × 10.4–2 × 10.7 cell L−1) in depth, with abundance inversely related to tidal currents. The functional structure of the phytoplankton community measured by functional diversity (FD), varied seasonally in and across a gradient of tidal energy. A core community, mainly represented by flagellates and dinoflagellates, occurred in all observations and was highly functional (high FD), exploiting a variety of habitats. The chain‐forming diatoms were associated with high tidal energy, and occurred in higher densities during summer. Phytoplankton cell size, cell shape, and the ability to form colonies are extremely plastic traits that can be regulated by the environment, however, isolated tychopelagic diatoms were present in the study area across all seasons, with higher contributions in autumn and winter, reflecting the shallow characteristic of this system. During the winter, an exposed sandbar was formed, and the lack of connection with the ocean resulted in an abundance of riverine and brackish water taxa. In this near‐pristine estuary the densities and occurrences of HAB phytoplankton are low. Trait‐based analyses add information about community structure, which can be impacted by anthropogenic actions in urbanized coastal systems. Thus the information provided by this study regarding phytoplankton functional diversity and its relation to nutrients and hydrography in Barra Grande Estuary can be applied as a baseline model for the development of public policies.

The significance of marine microfossils for paleoenvironmental reconstruction of the Solimões Formation (Miocene), western Amazonia, Brazil

Micropalaeontological studies of borehole cores 1AS-7D-AM and 1AS-8-AM, from Atalaia do Norte, Amazonas state, Brazil, support previous evidence for Miocene marine ingressions in Western Amazonia. Three marine incursion events are recorded: the first in the Early/early Middle Miocene (in both cores), the second in the late Middle/early Late Miocene (1AS-8-AM), and the third in the Late Miocene (1AS-7D-AM). The first event is characterized by exclusively mangrove taxa, and the last two present a mixture of marine, fresh, and brackish water taxa. However, at the end of the third event an increase of fluvial influence is demonstrated by the predominance of freshwater taxa. These marine incursions reached the study area through narrow and geographically limited connections, controlled by the tectonic setting, at a time between the Early/early Middle Miocene and late Middle/Late Miocene. Thereafter, fluvial conditions were reestablished before Pliocene times.

Cyprideis torosa(Jones, 1850) in its type area and stratigraphical context: potential for mapping the freshwater/estuarine boundaries of the Thames–Medway river system in the MIS 9 and MIS 11 interglacials

This study explores the potential of the ostracod Cyprideis torosa (Jones, 1850) as a brackish-water indicator for mapping freshwater/estuarine boundaries in Pleistocene interglacials in SE England. Ostracod species records from MIS 9 (Purfleet) and MIS 11 (Hoxnian) interglacial sites are mapped onto established palaeogeographies of the Thames–Medway river system, revealing distribution patterns indicative of a salinity gradient from west (freshwater) to east (brackish estuarine) in both cases. Comparisons with the ostracod biofacies of the present-day Thames Estuary suggest there may be no exact modern analogue for the Thames/Medway palaeoenvironments of the MIS 9 and MIS 11 interglacials. A similar conclusion is drawn from discussion of noding in C. torosa , which is common in the interglacial assemblages but extremely rare in the modern estuary. The value of mapping C. torosa onto estuarine palaeogeography is limited by taphonomic considerations because post-mortem transport and mixing in a macrotidal estuary significantly influence the composition of ostracod assemblages. Nevertheless, its use in combination with other brackish-water taxa provides useful insights regarding the palaeosalinity regimes of the lower River Thames and River Medway during the MIS 9 and MIS 11 interglacials.

Seasonal distribution of zooplankton in the Aby-Tendo-Ehy lagoons system (Côte d’Ivoire, West Africa)

Zooplankton is essential components of aquatic ecosystem where it contributes to transferring energy and organic matter from the primary producers to the higher trophic level taxa. However, changes in some environmental characteristics strongly influence their diversity and abundance. This work aimed at determining the spatial and seasonal distributions of zooplanktonic fauna in relation to some physico-chemical parameters in the Aby-Tendo-Ehy lagoons system. Zooplankton samples were collected monthly from March 2012 to February 2013 in six sampling sites with a cylindro-conical net of 64 μm in mesh opening size. Sampling observation showed of 53 taxa including Rotifera, Copepoda and Cladoceran. Rotifera was the most abundant group (83% of total abundance). Overall taxa diversity increased from Aby lagoon (n = 46) to Ehy lagoon (n = 50). The total abundance of zooplankton increased from Aby lagoon (mean = 122.8 ind/l) to Ehy lagoon (mean = 167.4 ind/l). Zooplankton abundance in Tendo and Ehy lagoons were dominated by freshwater taxa (Lecane leontina) while in Aby lagoon this parameter was dominated by brackish water taxa (Brachionus plicatilis). This study revealed that, in Aby lagoon, zooplankton was influenced mainly by salinity, transparency, dissolved oxygen and conductivity. However, in Ehy lagoon zooplankton was influenced by temperature and pH during the dry season. In Tendo lagoon, main factors are depth during the dry season and pH and temperature during the rainy season.© 2015 International Formulae Group. All rights reserved.Keywords: Zooplankton, abundance, community distribution, environmental variables, Aby-Tendo-Ehy lagoons, Côte d’Ivoire

Late Paleocene glyptosaur (Reptilia: Anguidae) osteoderms from South Carolina, USA

AbstractHeavily tuberculated glyptosaur osteoderms were collected in an active limestone quarry in northern Berkeley County, South Carolina. The osteoderms are part of a highly diverse late Paleocene vertebrate assemblage that consists of marine, terrestrial, fluvial, and/or brackish water taxa, including chondrichthyan and osteichthyan fish, turtles (chelonioid, trionychid, pelomedusid, emydid), crocodilians, palaeopheid snakes, and a mammal. Calcareous nannofossils indicate that the fossiliferous deposit accumulated within subzone NP9a of the Thanetian Stage (late Paleocene, upper part of Clarkforkian North American Land Mammal Age [NALMA]) and is therefore temporally equivalent to the Chicora Member of the Williamsburg Formation. The composition of the paleofauna indicates that the fossiliferous deposit accumulated in a marginal marine setting that was influenced by fluvial processes (estuarine or deltaic).The discovery of South Carolina osteoderms is significant because they expand the late Paleocene geographic range of glyptosaurines eastward from the US midcontinent to the Atlantic Coastal Plain and provide one of the few North American records of these lizards inhabiting coastal habitats. This discovery also brings to light a possibility that post-Paleocene expansion of this group into Europe occurred via northeastward migration along the Atlantic coast of North America.

New Information on Tataouinea hannibalis from the Early Cretaceous of Tunisia and Implications for the Tempo and Mode of Rebbachisaurid Sauropod Evolution.

The rebbachisaurid sauropod Tataouinea hannibalis represents the first articulated dinosaur skeleton from Tunisia and one of the best preserved in northern Africa. The type specimen was collected from the lower Albian, fluvio-estuarine deposits of the Ain el Guettar Formation (southern Tunisia). We present detailed analyses on the sedimentology and facies distribution at the main quarry and a revision of the vertebrate fauna associated with the skeleton. Data provide information on a complex ecosystem dominated by crocodilian and other brackish water taxa. Taphonomic interpretations indicate a multi-event, pre-burial history with a combination of rapid segregation in high sediment supply conditions and partial subaerial exposure of the carcass. After the collection in 2011 of the articulated sacrum and proximalmost caudal vertebrae, all showing a complex pattern of pneumatization, newly discovered material of the type specimen allows a detailed osteological description of Tataouinea. The sacrum, the complete and articulated caudal vertebrae 1–17, both ilia and ischia display asymmetrical pneumatization, with the left side of vertebrae and the left ischium showing a more extensive invasion by pneumatic features than their right counterparts. A pneumatic hiatus is present in caudal centra 7 to 13, whereas caudal centra 14–16 are pneumatised by shallow fossae. Bayesian inference analyses integrating morphological, stratigraphic and paleogeographic data support a flagellicaudatan-rebbachisaurid divergence at about 163 Ma and a South American ancestral range for rebbachisaurids. Results presented here suggest an exclusively South American Limaysaurinae and a more widely distributed Rebbachisaurinae lineage, the latter including the South American taxon Katepensaurus and a clade including African and European taxa, with Tataouinea as sister taxon of Rebbachisaurus. This scenario would indicate that South America was not affected by the end-Jurassic extinction of diplodocoids, and was most likely the centre of the rapid radiation of rebbachisaurids to Africa and Europe between 135 and 130 Ma.

Macrobenthos of the Ob River estuarine zone and of the adjacent regions of the Kara Sea

The composition and distribution of the macrobenthic communities in the Ob estuary and the adjacent Kara Sea shelf were studied during the 54th cruise of the R/V Akademik Mstislav Keldysh. With the transition from the Ob River’s mouth to the open parts of the sea, the gradual changes of the bottom biocenoses included changes in the leading taxa. Along with the increase in the salinity, the freshwater and brackish water taxa are replaced by related forms adapted to dwelling in seawater. The comparison of the original data with the results of the previous investigations revealed considerable spatial and temporal variations of the bottom communities in the studied area. The main environmental factors determining the fauna distribution in the estuarine zone are discussed. The extensive biocenosis dominated by Portlandia aestuariorum in the Ob estuary was found for the first time.

Ecrobia grimmi in brackish Lake Sawa, Iraq: indirect evidence for long-distance dispersal of hydrobiid gastropods (Caenogastropoda: Rissooidea) by birds

Ecrobia grimmi in brackish Lake Sawa, Iraq: indirect evidence for long-distance dispersal of hydrobiid gastropods (Caenogastropoda: Rissooidea) by birds

Biotic variation in coastal water bodies in Sussex, England: Implications for saline lagoons

Coastal water bodies are a heterogeneous resource typified by high spatial and temporal variability and threatened by anthropogenic impacts. This includes saline lagoons, which support a specialist biota and are a priority habitat for nature conservation. This paper describes the biotic variation in coastal water bodies in Sussex, England, in order to characterise the distinctiveness of the saline lagoon community and elucidate environmental factors that determine its distribution. Twenty-eight coastal water bodies were surveyed for their aquatic flora and invertebrate fauna and a suite of exploratory environmental variables compiled. Ordination and cluster analyses were used to examine patterns in community composition and relate these to environmental parameters. Biotic variation in the coastal water body resource was high. Salinity was the main environmental parameter explaining the regional distribution of taxa; freshwater and saline assemblages were evident and related to sea water ingress. Freshwater sites were indicated by the plant Myriophyllum spicatum and gastropod mollusc Lymnaea peregra, while more saline communities supported marine and brackish water taxa, notably a range of chlorophytic algae and the bivalve mollusc Cerastoderma glaucum. Site community differences were also related to bank slope and parameters describing habitat heterogeneity. A saline lagoon community was discerned within the matrix of biotic variation consisting of specialist lagoonal species with associated typically euryhaline taxa. For fauna, the latter were the molluscs Abra tenuis and Hydrobia ulvae, and the crustaceans Corophium volutator and Palaemonetes varians, and for flora they were the algae Ulva lactuca, Chaetomorpha mediterranea, Cladophora spp. and Enteromorpha intestinalis. One non-native polychaete species, Ficopomatus enigmaticus, also strongly influenced community structure within the lagoonal resource. The community was not well defined as specialist and associated taxa were distributed throughout the spectrum of sites surveyed. Implications for the identification and conservation of saline lagoons are discussed.

When DNA puts ecological works back on the right track: genetic assessment and distribution patterns of mudsnail populations in the Evros Delta lagoons

The present study aims to assess the distribution patterns of mudsnail populations in the Evros Delta lagoons and to investigate the key environmental variables affecting them. As a correct species assignment is crucial for ecological studies, the data presented here are substantiated using DNA sequences from the mitochondrial genome to verify the systematic status of the mudsnail taxon in question. A comparative molecular analysis involving almost all brackish-water taxa of Hydrobiinae indicates that the populations from the Evros Delta belong to the Pontic species Ventrosia maritima, a taxon that was not reported before from the Mediterranean. Moreover, it appears that in previous studies, the mudsnail populations from the Evros Delta were misidentified. Principal Component Analyses using environmental variables defined station groups among which V. maritima showed a significant variation in density. Mudsnail specimens were absent at stations with an immediate access to the sea (salinity 32-34 PSU, very fine to fine sand, organic matter 0.3-1.4 %), they showed intermediate densities (up to 3,000 ind./m 2 ) in innermost lagoonal parts (34-35 PSU, very fine sand, organic matter 1.0-1.4 %) and relatively high densities (up to 7,000 ind./m 2 ) only in isolated parts (15-17 PSU, fine sand, organic matter 0.5-0.8 %). Contact with the sea, which is strongly correlated with seawater renewal rate and hydrodynamism, was found to be the most important factor affecting mudsnail distributions. The data presented, being the first detailed ecological information available for V. maritima, are compared with the available information for other mudsnail taxa. The present study not only lays the foundation for future comparative eco-genetic works of mudsnail taxa, it also stresses the absolute need for the routine usage of molecular markers in ecological studies involving frequently utilized but systematically poorly understood invertebrate species.

Late Pleistocene stratigraphy at Boliden, northern Sweden

Till‐covered sand and silt sediments with organic material from Boliden, northern Sweden, have been resampled and reinvestigated. Texture and petrographic analyses demonstrated one till bed overlying, and one underlying the sandy sediments. Low frequencies of diatoms were noted, representing freshwater, halophilous and brackish water taxa. The diatoms may be allochthonous or autochthonous, or redeposited from older deposits. Pollen analysis revealed a new picture of the composition of the vegetation, as compared with earlier investigations. The flora consisted of an arctic‐subarctic treeless shrub and herb vegetation dominated by Salix, Betula nana, Gramineae and Cyperaceae. Artemisia and several arctic‐alpine herbs were important elements. The identification of Salix wood as well as fruits and fruit scales of Betula nana and Betula cf. humilis is in agreement with the pollen‐analytical results, as is the occurrence of Nordicboreal species of Coleoptera. Two radiocarbon datings resulted in an age of c. 45,000 B. P. and >40,000 B.P. The Boliden till‐covered sediments were most probably deposited during an Early or Middle Weichselian interstadial, but the initial or final stage of an interglacial (Eemian) is also possible.

DIATOM ASSOCIATIONS IN YAQUINA ESTUARY, OREGON: A MULTIVARIATE ANALYSIS1

SUMMARYA cluster analysis and a principal components analysis were performed to examine the degree to which the diatom flora of Yaquina estuary can be partitioned into discrete associations and to relate the composition of the flora to selected physical properties of the estuary. The species composition of the diatom flora during the winter was more closely associated with salinity and intertidal exposure them in the summer. A cluster of freshwater taxa obtained for the winter data was the most conspicuous diatom association defined by the cluster analysis. Although taxa within a cluster had more similar distributions than taxa from different clusters, there was considerable variation in the distributions of marine and brackish water taxa within a multispecies cluster.

Diatom Succession in a Core from Pickerel Lake, Northeastern South Dakota

Percentage analyses of the diatoms from a core of sediment show the changes in the community since the formation of Pickerel Lake. The lake basin is in calcareous drift from the Wisconsin glaciation and is located on the Coteau des Prairies upland. This work supplements earlier studies of the pollen, plant macrofossils, and mollusks made by Watts and Bright (1968), in which they presented evidence for four vegetational stages: (1) spruce forest, (2) deciduous woodland, (3) bluestem prairie, and (4) continued open prairie with the return of some woodland. The diatom core was correlated with the nearby pollen core by pollen analysis. The diatom succession begins in diatom zone I, with an assemblage dominated by Fragilaria and Mastogloia species and containing many taxa of alkaline waters. It also includes several taxa that generally prefer acid environments and only occur in the lower part of this core. This diatom assemblage is correlated primarily with the presence of spruce forest and its associated soils; the change in the diatoms occurs when the deciduous woodland that follows is partly replaced by prairie openings. It is suggested that the changes in the type of material (mainly soil) washed into the lake produced a more alkaline environment, which excluded some of the acidophilous taxa. Diatom zone II is largely transitional to zone III, which is dominated by Melosira species and includes many indicators of a more eutrophic (nutrient-rich) environment, for example Fragilaria crotonensis. More brackish-water taxa also indicate an increase in the mineral content of the water. All of these features are consistent with evidence from the pollen stratigraphy, which indicates that this is the time of maximum prairie development in this area, along with maximum soil erosion and lake-water evaporation. Diatom zone IV is largely transitional, corresponding to the time when woodland was once again developing around the margins of the lake basin. Diatom zone V features increasing percentages of forms characteristic of surf zones in lakes, indicating perhaps a shallowing of the site as a result of sedimentation. There is some indication of recent enrichment, concurrent with an increase in Ambrosia pollen (ragweed), which is possibly due to disturbance by man. The use of a constant volume of material in the diatom preparation makes it possible to draw a diagram of diatom abundance for each level. The diatoms are scarce in samples from the lower part of the core, and four radiocarbon dates bear out a suggestion that more inorganic material was deposited at the core site during the early history of the lake than subsequently. A total of 207 taxa is reported, and ecological notes on all are included in an appendix. A diatom diagram shows curves for 71 of the taxa.