Normal Waters Research Articles

Aquatic insects as bioindicators of stream water quality - a seasonal analysis on Western Ghats river, Muthirapuzha, in central Kerala, India

This study was conducted to assess the water quality of Muthirapuzha River, Idukki using aquatic insects as bioindicators. Insects were collected on a seasonal basis from February 2014 to January 2015 from 12 sampling stations. Insects were sampled using standard collection methods and were identified up to family level. A total of 3,278 individuals belonging to seven orders and 37 families were collected during the study period. The greatest number of taxa was represented by order Ephemetroptera during monsoon (27%) and post-monsoon (25%), while Diptera (22.7%) dominated the pre-monsoon season. Shannon Weiner diversity index, Simpson dominance index, and Margalef’s richness index was highest post-monsoon. The EPT score in Muthirapuzha was for normal waters, however, pre-monsoon values were lowest, indicating pollution load during this period. Hilsenhoff’s family biotic index (HFBI) was used to estimate the status of organic pollution along the river based on representative families of aquatic entomofauna; values were highest at pre-monsoon season. The overall organic water quality level in the Muthirapuzha was good to fair based on this study.

Foraminiferal Biostratigraphy and Paleoecology of the Southeasternmost Outcrops of the Oligocene Qom Formation, SE Iran

Abstract The Qom Formation is deposited along more than 1800 km of the NE margin of the Tethyan Seaway in the Oligocene-Early Miocene during the final sea transgression on the Iranian Plate. We present (foraminiferal-based) biostratigraphic data from three exposed sections near the northwestern Jazmurian Lake, as the southeasternmost outcrops of the Qom Formation. Larger benthic foraminifera are mainly represented by nummulitids (Nummulites, Operculina, Heterostegina), lepidocyclinids (Nephrolepidina, Eulepidina, Lepidocyclina), and Amphistegina. The presence of Nummulites fichteli/intermedius and Nummulites vascus in the lower parts of the study sections together with lepidocyclinids indicates that their basal deposits could be attributed to the late Rupelian. The Qom Formation is of late Rupelian-Chattian in age in all three stratigraphic sections. Also, the presence of Nummulites- bearing tuffaceous limestones and tuff unit in the lower part of the Bozadan section is indicative of contemporaneous volcanic activity. Most parts of the study sections with an association of large and flat perforate foraminifera were deposited in normal saline waters. These parts are presented by large and flat nummulitids, lepidocyclinids, and Amphistegina. These large and flat perforate foraminifera often dominate in the lower part of the photic zone. The abundance of larger benthic foraminiferal and coralline red algae and the coral facies indicates a tropical-subtropical palaeoenvironment.

Sedimentary porewaters record regional tectonic and climate events that perturbed a deep-sea brine pool in the Gulf of Aqaba, Red Sea

Brine pools in deep-sea environments provide unique perspectives into planetary and geological processes, extremophile microbial communities, and sedimentary records. The NEOM Brine Pool Complex was the first deep-sea brine pool system found in the Gulf of Aqaba, representing a significant extension of the geographical range and depositional setting of Red Sea brine pools. Here, we use a combination of brine pool samples collected via cast using a conductivity, temperature, depth instrument (CTD), as well as interstitial porewaters extracted from a sediment core collected in the NEOM Brine Pool to characterize the chemical composition and subsurface evolution of the brine. New results indicate that the NEOM brines and the subsurface porewaters may originate from different sources. Elemental concentrations suggest the brines in the NEOM pool are likely derived from dissolution of sub-seabed evaporites. In contrast, the sedimentary porewaters appear to have been influenced by periodic turbidite flows, generated either by earthquakes, submarine landslides, or flash floods, in which normal marine waters from the overlying Red Sea became entrained, periodically disturbing the chemistry of the brine pool. Thus, sediment porewaters beneath brine pools may record transient and dynamic changes in these deep marine depositional environments, reflecting the interplay between climate, tectonics, and sedimentation patterns along a rapidly urbanizing coastline. In concert, new results from NEOM extend the range and chemical constraints on Red Sea Brine Pools and highlight the dynamic interplay between Red Sea Deep water, dissolving evaporites, turbidites, and subsurface fluids that produce these unique depositional environments which host microbial life at the edge of habitability. In concert with sedimentological indicators, the chemistry of porewaters beneath deep-sea brine pools may present detailed records of natural hazards arising from interactions between the atmosphere, lithosphere, hydrosphere, and anthroposphere.

Tidal Dynamics And Physicochemical Parameters In A Tropical Estuary: Qua-Iboe River Estuary, Southeast Coast Of Nigeria

Estuaries are important ecosystems that support biodiversity and influence the economy of the regions they occupy. Major physicochemical variables of Qua-Iboe River estuary in the Niger Delta region of Nigeria were assessed for ecosystem quality. The influence of tidal current on the spatial distribution of physicochemical parameters in the estuary was examined. Physicochemical parameters, including transparency, temperature, salinity, dissolved oxygen, density and pH were measured in-situ during the dry season. Tidal current velocities were monitored over spring and neap tidal cycles using the Langragian method and results indicated ebb dominance. The relationships between physicochemical parameters were statistically analyzed using Pearson’s correlation matrix. Based on Pearson’s correlation, density showed significant correlations (p < 0.05) with temperature, pH and salinity. Surface and bottom water temperatures significantly correlated (p < 0.05) with density, salinity, dissolved oxygen and pH. Spatial distribution maps of physicochemical parameters were plotted using ArcGIS Pro. Similarities and dissimilarities of surface and bottom water parameters were interpreted using cluster analysis. Results revealed two groups reflecting distinct physicochemical characteristics in the study area. Group one, representing upper and central portions of the estuary is defined by waters which are limnetic to oligohaline, slightly acidic to neutral with low dissolved oxygen (<4mg/l) conditions. The estuary showed limnetic conditions at the upper reaches due to the strong fluvial input by the Qua-Iboe River. Group two, representing the lower estuary, is characterized by mesohaline to normal marine waters; neutral to slightly alkaline pH, and low dissolved oxygen (< 4mg/l) conditions. This study is relevant for future monitoring and assessment of the estuary and similar tidal ecosystems.
 

Acoustic data from the spring 2011 bowhead whale census at Point Barrow, Alaska

Bowhead whales generally migrate into high Arctic waters in the summer months and move to lower latitudes in the wintertime. During the 1800s and early 1900s commercial whaling greatly reduced the numbers of bowhead whales in waters adjacent to the North Atlantic Ocean. In recent decades their numbers have been increasing. Thirteen sightings of a bowhead whale were recorded in four areas of the Gulf of Maine in 2012, 2014, and 2017 between latitudes 44°43’N and 41°36’N, far south of the normal range (54°N) for this species. Photographs obtained during these sightings were compared by experienced photo analysts and, based on scarring patterns, the sightings were confirmed to be of the same individual. The bowhead whale was observed alone, in addition to interacting in a social group and engaged in coordinated feeding with other mysticetes at times. The feeding and social behaviour of the bowhead whale was typical for the species but well south of its normal Arctic waters range and in the absence of conspecifics.

Sightings of a bowhead whale (Balaena mysticetus) in the Gulf of Maine and its interactions with other baleen whales

Bowhead whales generally migrate into high Arctic waters in the summer months and move to lower latitudes in the wintertime. During the 1800s and early 1900s commercial whaling greatly reduced the numbers of bowhead whales in waters adjacent to the North Atlantic Ocean. In recent decades their numbers have been increasing. Thirteen sightings of a bowhead whale were recorded in four areas of the Gulf of Maine in 2012, 2014, and 2017 between latitudes 44°43’N and 41°36’N, far south of the normal range (54°N) for this species. Photographs obtained during these sightings were compared by experienced photo analysts and, based on scarring patterns, the sightings were confirmed to be of the same individual. The bowhead whale was observed alone, in addition to interacting in a social group and engaged in coordinated feeding with other mysticetes at times. The feeding and social behaviour of the bowhead whale was typical for the species but well south of its normal Arctic waters range and in the absence of conspecifics

Palaeoecological and palaeobiogeographic implications of Middle‐Late Eocene ostracods from the Qattamiya area, North Eastern Desert, Egypt

In an attempt to define the palaeoecology and palaeobiogeography of the Middle‐Late Eocene rock units in the North Eastern Desert of Egypt, 121 rock samples of three representative localities, namely, Wadi Degla, Gebel Abu‐Shama, and Gebel Qattamiya sections were collected and investigated. Qualitative and quantitative analysis of ostracods associations and sedimentological data were used to identify three ostracod biozones; two acme zones (Cytherella tarabulusensis and Loxoconcha vetustopunctatella) of the Middle Eocene age and one assemblage zone (Xestoleberis subglobosa–Uromuellerina saidi) of Middle‐Late Eocene age, reflecting palaeoenvironments in the study area. The Cytherella tarabulusensis Zone, located at the bottom of all sections, is characterized by restricted shallow water, low dissolved oxygen, high salinity, and water depth below 100 m. The Loxoconcha vetustopunctatella Zone, located in Wadi Degla and Gebel Qattamiya sections, is characterized by shallow normal warm waters in the range of 20–50 m, whereas Xestoleberis subglobosa–Uromuellerina saidi Assemblage Zone, located in all studied sections, reflects restricted shallow water with a reduced dissolved oxygen condition palaeoenvironment. Palaeobiogeographically, the recorded ostracod assemblage exhibits similarities with those recorded in the Middle East and North and East Africa bioprovinces.

Food habits of greenback mullet Liza subviridis at Lampon Estuary, Banyuwangi, East Java

The mullet is a fish that dominates the Lampon Estuary. These waters contain Pb and Hg that exceed the threshold. This study aims to look at the mullet food habits, water quality, and the relationship between water quality and mullet food habits. This research was conducted for three months, from November 2019 to January 2020 at Estuary Lampon, Pesanggrahan, Banyuwangi, East Java. This research used a survey method (non-experimental) and observation method. The number of fish samples was 171 fish. Based on the analysis, the composition of mullet fish feed consists of Diatoms, Flagellates, Chlorophyceae, Bacillariophyta, Xanthophyta, and Dinoflagellates. The composition of plankton as food in polluted waters obtained a different type of plankton from normal waters. Based on the index value of food choices, the most popular food is Diatoms and can be categorized as herbivorous fish.

STUDI IDENTIFIKASI KUALITAS AIR DAN JENIS IKAN AIR TAWAR DI SUMBER AIR PANAS DESA NYELANDING KABUPATEN BANGKA SELATAN SEBAGAI DASAR PENGELOLAAN POTENSI KAWASAN AIR PANAS UNTUK KEGIATAN PERIKANAN DAN WISATA

Hot springs in Nyelanding Village, South Bangka Regency, have the potential of geothermal resources that can be used as a potential energy source, moreover found several types of freshwater fish that utilize these hot springs as their natural habitat. The objectives of this study are to identify the water quality and diversity of freshwater fish species in the hot spring area of Nyelanding Village, South Bangka Regency; analyze the feasibility of water quality for fisheries and tourism activities; and analyzing fish growth patterns found at these locations. The results showed that there were two types of fish found in the hot springs of Nyelanding Village, which were Gabus Fish (Channa striata) and Sepat Fish (Trichogaster trichopterus). There are 6 hot water quality parameters Village Nyelanding included in standard class II PP 82 of 2001 include pH, COD, TSS, TDS, Nitrate and Total fospat, two parameters are not required (depth and ammonia), one parameter (temperature ) not in normal natural waters. The growth pattern of Gabus Fish in the hot water of Nyelanding Village is negative allometric with a growth coefficient of 2.076. In general, based on the analysis of water quality parameters, the Nyelanding Village hot water is suitable for biota life as well as aquaculture activities and tourist areas. For aquaculture, the recommended type of fish is eurythermal. However, their habit of draining the hot water pool Village Nyelanding made towards development of the area is less recommended for fishing activity, but preferably as a tourist area.

Central Tethyan platform-top hypoxia during Oceanic Anoxic Event 1a

Abstract. Short-term hypoxia in epeiric water masses is a common phenomenon of modern marine environments and causes mass mortality in coastal marine ecosystems. Here, we test the hypothesis that during the early Aptian, platform-top hypoxia temporarily established in some of the vast epeiric seas of the central Tethys and caused, combined with other stressors, significant changes in reefal ecosystems. Potentially interesting target examples include time intervals characterized by the demise of lower Aptian rudist–coral communities and the establishment of microencruster facies, as previously described from the central and southern Tethys and from the proto-North Atlantic domain. These considerations are relevant as previous work has predominantly focused on early Aptian basinal anoxia in the context of Oceanic Anoxic Event (OAE) 1a, whereas the potential expansion of the oxygen minimum zone (OMZ) in coeval shallow-water environments is underexplored. Well-known patterns in the δ13C record during OAE 1a allow for a sufficiently time-resolved correlation with previously studied locations and assignment to chemostratigraphic segments. This paper presents and critically discusses the outcome of a multi-proxy study (e.g., rare earth elements (REEs), U isotopes, and redox-sensitive trace elements) applied to lower Aptian shallow-water carbonates today exposed in the Kanfanar quarry in Istria, Croatia. These rocks were deposited on an extensive, isolated high in the central Tethys surrounded by hemipelagic basins. Remarkably, during chemostratigraphic segment C2, the depletion of redox-sensitive trace elements As, V, Mo, and U in platform carbonates, deposited in normal marine oxic waters, record the first occurrence of basinal, organic-rich sediment deposition in which these elements are enriched. During the C3 segment, seawater oxygen depletion established on the platform top as indicated by the patterns in Ce/Ce* and U isotopes. Shifts in redox-sensitive proxies coincide with the expansion of microencruster facies. Segment C4 witnesses the return to normal marine reefal faunas on the platform top and is characterized by patterns in redox-sensitive proxies typical of normal marine dissolved oxygen levels. It remains unclear, however, if platform-top hypoxia resulted from the expansion and upwelling of basinal, oxygen-depleted water masses or if spatially isolated, shallow hypoxic water bodies formed on the platform. Data shown here are relevant as they shed light on the driving mechanisms that control poorly understood faunal patterns during OAE 1a in the neritic realm and provide evidence on the intricate relation between basinal and platform-top water masses.

Taphonomy of fish concentrations from the Upper Jurassic Solnhofen Plattenkalk of Southern Germany

The density of vertebrate fossils on bedding planes is generally very low in the Upper Jurassic plattenkalks forming the Solnhofen fossil Lagerstatte. There are, however, a few bedding planes where large concentrations of the small fis Leptolepides sprattiformis (BLAINVILLE, 1818) occur. The aim of this paper is to analyse and interpret these f sh concentrations from a taphonomic point of view. For this purpose, the taphonomic features of L. sprattiformis concentrations on three large slabs were semi-quantitatively analysed. The concentrations of individuals on bedding planes are explained as recording local mass mortality events caused by tropical storms that, for short intervals, disrupted the pycnocline which separated hypersaline, oxygen-poor to anoxic bottom waters from normal marine surface waters in the Plattenkalk basins. Mass mortality is supported by tetany features such as gaping jaws, hyperextended branchiostegal rays, and splayed f ns, which occur in the majority of the specimens. The generally excellent preservation of the f sh resulted from lack of postmortem f oatation, rapid burial and/or overgrowth by microbial f lms, and quick re-establishment of the pycnocline with inhospitable conditions on the basin floo. The post-mortem concave-arching of the backbones and various displacements of the vertebral column were most likely caused by varying decay resistance of soft tissues and the pressure of decay gases in the body cavities, respectively. The taphonomic analysis of f sh concentrations can provide very detailed palaeoenvironmental information and serves as an independent line of evidence for palaeoenvironmental reconstructions that complements geochemical and sedimentary data.

Large Sea Surface Temperature, Salinity, and Productivity‐Preservation Changes Preceding the Onset of the Messinian Salinity Crisis in the Eastern Mediterranean Sea

AbstractThe Messinian Salinity Crisis (MSC; 5.97–5.33 Ma) is an enigmatic episode of paleoceanographic change, when kilometer‐thick evaporite units were deposited in the Mediterranean basin. Here we use geochemical (biomarker and isotope) data to reconstruct sea surface temperature, salinity, and productivity‐preservation changes in the Mediterranean basin just before the MSC. The proxy data indicate that the Mediterranean Sea was significantly saltier and colder between 6.415 and 6.151 Ma, than between 6.151 and 5.971 Ma. Salinity decrease at 6.151 Ma seems to be a relatively fast event just preceding the inception of a warming phase that lasted almost uninterrupted until the MSC onset. The water exchange with the Paratethys could have caused, along with the African rivers, an increased freshwater supply, resulting in normal marine Mediterranean waters between 6.151 and 5.971 Ma, despite the severe restriction of marine connections with the Atlantic at that time. Sea surface temperature changes determined a sharp drop in productivity and/or preservation of organic matter, marked by deposition of calcareous marls. Productivity and preservation were relatively high and constant until 6.01 Ma. Afterward, increased influx of terrestrial organic matter and probably enhanced water column stratification prevailed. Around 5.971 Ma, modifications in aquatic versus terrestrially derived biomarkers indicate changes in organic matter influx at the MSC onset.

Biomass burning and carbon monoxide patterns in Brazil during the extreme drought years of 2005, 2010, and 2015

In the 21st century, severe droughts associated with climate change will increase biomass burning (BB) in Brazil caused by the human activities. Recent droughts, especially in 2005, 2010, and 2015, caused strong socioeconomic and environmental impacts. The 2015 drought considered the most severe since 1901, surpassed the 2005 and 2010 events in respect to area and duration. Herein, based on satellite data, the 2005, 2010 and 2015 drought impacts on wildfire episodes and carbon monoxide (CO) variability during the dry and the dry-to-wet transition seasons were examined. The BB occurrences in the dry season were fewer during 2015 than during 2005 (−44%) and 2010 (−47%). Contrasting, the BB events in the dry-to-wet transition season, were higher during 2015 than during 2005 (+192%) and 2010 (+332%). The BB outbreaks were concentrated in the southern and southwestern Amazon during 2005, in the Cerrado region during 2010, and mainly in the central and northern Amazon during 2015, an area normally with few fires. The CO concentration showed positive variations (up to +30%) occurred in the southern Amazon and central Brazil during the 2005 and 2010 dry seasons, and north of 20 °S during the 2015–2016 dry-to-wet transition season. The BB outbreaks and the CO emissions showed a considerable spatiotemporal variability among the droughts of 2005, 2010, and 2016, first of them driven by local conditions in the tropical North Atlantic (TNA), characterized by warm than normal sea surface waters and the other two by the El Niño occurrences.

Palaeoecological analysis of Sentolo Formation based on foraminifera fossil assemblage from stratigraphic cross-sectional measurements in Pengasih, Kulon Progo, Yogyakarta

Sentolo formation that is included in the Kulon Progo stratigraphic series has a wide distribution. Although there have been a number of studies on it, more detailed research is needed, as there are still many unexplored outcrop locations. Moreover, there are still a lot of questions about the stratigraphic relationship between Sentolo Formation and Oligocene-Miocene volcanic series of Kulon Progo. Based on this background, this study is focused on the existence of foraminifera fossil in Sentolo Formation as an indicator of palaeoecological conditions at the time Sentolo Formation was deposited. This research is very important to get a detail understanding about the indicators that are influential at the time of deposition process of Sentolo Formation in research area. Based on palaeoecological analysis, the palaeoecology at the time Sentolo Formation deposited was normal marine continental slope waters. Meanwhile, the community structure of foraminifera indicates a stable water conditions in a marine environment that was not disrupted by volcanism, so it becomes a good factor for the growth of foraminifera. Whereas the presence of volcaniclastic material mixed with carbonate which is occurred in the lower part of Sentolo Formation were interpreted as reworked of older volcanic rock.

Paleoenvironmental conditions of Early Miocene corals, western Makran, Iran

Miocene coral-bearing limestones, distributed in the western Makran Basin, are attributed to Aquitanian and Burdigalian. This investigation is focused on three Early Miocene coral-bearing limestone sections in western Makran. Remarkably, well-preserved scleractinian corals and other components could be very definitive to reconstruct paleoenvironmental conditions. Lithologically, there are some differences between the studied sections. Furthermore, zooxanthellate corals are diverse and abundant in all sections. Based on different components and richness of zooxanthellate corals, it seems that the studied carbonate corals are precipitated in a subtropical condition, between 19 and 20 °C in all sections. In light of the dominancy of corals, the presence of symbiont-bearing larger benthic foraminifera (LBF), lithological features, bioeroding features, and encrusting organisms, the oligotrophic to slightly mesotrophic conditions are considered for Tejek section and the mesotrophic condition had been prevailed in Kermestan and Irer sections. According to light intensity in water column and coral morphotypes, Tejek section is considered to precipitate under euphotic to slightly mesophotic condition, while Kermestan and Irer sections were deposited under mesophotic to euphotic light conditions. In transparent water, photic zones continue to deeper depths, while in less transparent water, these zones are limited to shallower parts. A defined depth in the photic zone may represent euphotic, mesophotic, or oligophotic zone. Based on the water transparency, a taxon in a defined photic zone can occur in various depths. On the basis of trophic-light intensity-depth chart, the estimated depth ranges are 12–85 m for Tejek section and 5–62 m for Kermestan and Irer sections. Water energy as another important factor in environmental condition is acquired from coral morphotypes. Accordingly, Tejek section is precipitated under moderate-high energy and Kermestan and Irer sections are deposited in low to moderate-high energy. The presence of encrusting coralline algae, corals, and other constituents is indicative of different substrates in the studied areas. Corals favorably develop in normal salinity waters. The existence of colonial corals and occurrence of benthic foraminifera with hyaline wall indicate normal seawater conditions.

The use of cryoscopy method for determination of freezing temperature of waters having different content of deuterium

Using the method of cryoscopy we determined the freezing temperature of light water with D/H= 4.2 ppm, 18O/16O = 910 ppm. It was found that light water freezes at the above zero temperature (0.3 ± 0.1°C) irrespective of cooling rate. It is shown that light water begins to freeze only at an overcooled metastable state. Under conditions of experiment the nucleation and growth of dendrite crystals of ice depends on the cooling rate and starts at the temperature −5.3; −8.8; −9.8 ± 0.1°C at the average cooling rate respectively 0.2; 0.3; 0.5°C·min−1. It is shown than in usual water the growth of dendrite ice crystals starts at minus temperature (−6.4;−7.5; −8.8 ± 0.1°C) and increases with an increase of the average cooling rate respectively from 0.2 to 0.6°C·min−1. It was found that the initial freezing temperature of heavy water constituted −3.0− −4.0 ± 0.1° at the rate of its cooling 0.2−1.0°C·min−1. However in this case the freezing temperature of normal and heavy waters does not depend on the cooling rate and freezing of normal and heavy waters and according to reference data constitutes respectively 0.1 ± 0.1 and 3.9 ± 0.1°C.

Threats to Coastal Archaeological Sites and the Effects of Future Climate Change: Impacts of the 2011 Tsunami and an Assessment of Future Sea-Level Rise at Hōnaunau, Hawai’i

ABSTRACTClimate change, rising sea levels, and increases in storm intensity and frequency are developing issues for many coastal communities and will impact significant archaeological resources across the Pacific. The 9.0 magnitude Tohoku earthquake and resulting tsunami that occurred off of Honshu, Japan in 2011 were natural disasters that provided the National Park Service with the opportunity to observe the effects of higher than normal waters on coastal resources at Pu’uhonua o Hōnaunau National Historical Park. The 2011 tsunami inundated areas of the park up to 1.06 meters and caused damage to multiple site types and features. Although tsunami are not events caused by climate change, this natural disaster and its effects allowed insights into the future of park archaeological resources when sea-level rise and island subsidence are considered. When park resources were examined in relation to future sea-level rise (SLR) scenarios, models demonstrate that the park faces significant losses to archaeological resources with as little as a 0.5-meter rise in sea level. When the results of these models are considered with the estimated rates of island subsidence, SLR in this area could reach one meter or more by the end of the century.

Ecosystem health indicators in the Ganga Basin (Uttarakhand, India): Biodiversity, spatial patterns in structure and distribution of benthic diatoms, macro-invertebrates and ichthyofauna

This is the pioneering attempt to study the spatial patterns in structure of lotic ecosystems that form the Ganga River system in the Himalaya. The diversity of source (glacier-fed [GF], snow-fed [SN] and spring-fed [SF]) and stream-size (both interrelated) across the altitudinal panorama, create numerous habitats that contribute to structural diversity. The spatial patterns in richness, density and taxonomic composition and distribution of benthic diatoms are less affected by source compared with macro-invertebrates but shows strong influence on the distribution of fish fauna that are poikiliotherms, because a glacier-fed river carries ice-cold water (usually <20°C) in contrast to normal waters in spring-fed system (22°C near snowline, 32°C in foothills). The abundance patterns of biota of lower organisation grade (diatoms, macro-invertebrates) do not differ sharply even across distant river basins as they are more influenced by proximate factors; thus the sub-basins of the Alaknanda resemble more by virtue of one basin and there is notable resemblance between distant SF Bemunda (lower Ganga basin) and SF Gomti (East Rāmgangā basin) and even the farthest Yamuna and Rāmgangā. Fish are more sensitive to temperature and current velocities that are related to altitude and hence longitudinal rather than the spatial gradients in the mountains. The lotic ecosystem of Doon Valley harbour rich and diverse diatom flora, macroinvertebrate fauna and ichthyofauna. The examination of trophic, saprobic and ecological status shows that organic pollution, degradation and anthropogenic eutrophication are non-existent in the Lesser Himalayan rivers and streams, but the fragile Doon Valley is under severe anthropogenic stress. This and habitats fragmented by hydropower projects in the major rivers has threatened the iconic game fish Himalayan mahseer in the Ganga.

Carbon dioxide and hydrogen sulfide degassing and cryptic thermal input to Brimstone Basin, Yellowstone National Park, Wyoming

Brimstone Basin, a remote area of intense hydrothermal alteration a few km east of the Yellowstone Caldera, is rarely studied and has long been considered to be a cold remnant of an ancient hydrothermal system. A field campaign in 2008 confirmed that gas emissions from the few small vents were cold and that soil temperatures in the altered area were at background levels. Geochemical and isotopic evidence from gas samples (3He/4He~3RA, δ13C-CO2~−3‰) however, indicate continuing magmatic gas input to the system. Accumulation chamber measurements revealed a surprisingly large diffuse flux of CO2 (~277t d−1) and H2S (0.6t d−1). The flux of CO2 reduces the 18O content of the overlying cold groundwater and related stream waters relative to normal meteoric waters. Simple isotopic modeling reveals that the CO2 likely originates from geothermal water at a temperature of 93±19°C. These results and the presence of thermogenic hydrocarbons (C1:C2~100 and δ13C-CH4=−46.4 to −42.8‰) in gases require some heat source at depth and refute the assumption that this is a “fossil” hydrothermal system.

Tracing offshore low-salinity plumes in the Northeastern Gulf of Mexico during the summer season by use of multispectral remote-sensing data

To trace offshore surface low-salinity water (LSW) in the northeastern Gulf of Mexico, a proxy was developed using the surface water beam attenuation coefficient (cp), and salinity matched with synchronous Sea-viewing Wide Field-of-view Sensor (SeaWiFS) satellite data from three annual summer cruises (July 1998–August 2000) using a two-step empirical approach. First, a relationship between in-situ salinity and cp was obtained. Second, in-situ cp was matched with SeaWiFS radiance ratios of all available blue-to-green wavelengths. Finally, satellite-derived surface salinity was determined directly by combining the two empirical relationships, providing a robust estimate over a range of salinities (26–36). This significantly improves the limited spatial and temporal resolution of surface salinity distribution obtained by shipboard sampling. The resulting correlation is best explained as mixing between low-salinity plume waters and normal salinity Gulf waters. The empirical relationships were used to map satellite-derived salinity using the average of SeaWiFS images during each summer cruise. As expected for summer, spatial patterns of LSW plumes with high cp, particulate matter (PM), particulate organic carbon (POC), and chlorophyll-a (Chl-a) were connected to the mouth of the Mississippi River Delta and extended to the east-southeast. Normal salinity Gulf water with lower cp, PM, POC, and Chl-a was confined to the shelf and upper slope in the eastern part of the study area, outside the plumes. This proxy approach can be applied throughout the region of shipboard sampling for more detailed coverage and analysis.