Search results for "AQUATIC ORGANISMS"

Comment on "Lethally hot temperatures during the Early Triassic greenhouse".

2013

Sun et al . (Reports, 19 October 2012, p. 366) reconstructed Permian to Middle Triassic equatorial seawater temperatures. After correct temporal positioning of their data points, their presumed trends of temperature changes, and hence their assumption of a one-to-one relationship between putative "lethally hot" seawater temperatures and a disputable equatorial "eclipse" of some organisms, are no longer supported by their data.

Metallothionein in the freshwater gastropod Melanopsis dufouri chronically exposed to cadmium: A methodological approach

2010

Previous studies have demonstrated that the use of differential pulse polarography (DPP) for metallothionein (MT) determination in marine gastropod tissues, particularly the digestive gland, requires taking into account the presence of heat-stable high molecular weight compounds that exhibit polarographic signal. In the present paper, similar compounds were identified in tissues from the freshwater snail Melanopsis dufouri which also interfere with MT determination by DPP and, due to their silver binding capacity, also interfere in the silver assay for MT quantification. Ultrafiltration seems to be effective in removing these high molecular weight compounds from heat-denatured homogenate su…

2015

Marine indole alkaloids comprise a large and steadily growing group of secondary metabolites. Their diverse biological activities make many compounds of this class attractive starting points for pharmaceutical development. Several marine-derived indoles were found to possess cytotoxic, antineoplastic, antibacterial and antimicrobial activities, in addition to the action on human enzymes and receptors. The newly isolated indole alkaloids of marine origin since the last comprehensive review in 2003 are reported, and biological aspects will be discussed.

Predicting the bioaccumulation of polyaromatic hydrocarbons and polychlorinated biphenyls in benthic animals in sediments

2016

There were two main objectives in this study. The first was to compare the accuracy of different prediction methods for the chemical concentrations of polyaromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) in the organism, based on the measured chemical concentrations existing in sediment dry matter or pore water. The predicted tissue concentrations were compared to the measured ones after 28-day laboratory test using oligochaeta worms (Lumbriculus variegatus). The second objective was to compare the bioaccumulation of PAHs and PCBs in the laboratory test with the in situ bioaccumulation of these compounds. Using the traditional organic carbon-water partitioning model, tissue…

Individual and population-level responses to ocean acidification

2016

- Ocean acidification is predicted to have detrimental effects on many marine organisms and ecological processes. Despite growing evidence for direct impacts on specific species, few studies have simultaneously considered the effects of ocean acidification on individuals (e.g. consequences for energy budgets and resource partitioning) and population level demographic processes. Here we show that ocean acidification increases energetic demands on gastropods resulting in altered energy allocation, i.e. reduced shell size but increased body mass. When scaled up to the population level, long-term exposure to ocean acidification altered population demography, with evidence of a reduction in the …

Assessing host-parasite specificity through coprological analysis: a case study with species of Corynosoma (Acanthocephala: Polymorphidae) from marin…

2011

In this paper we report an investigation of the utility of coprological analysis as an alternative technique to study parasite specificity whenever host sampling is problematic; acanthocephalans from marine mammals were used as a model. A total of 252 scats from the South American sea lion, Otaria flavescens, and rectal faeces from 43 franciscanas, Pontoporia blainvillei, from Buenos Aires Province, were examined for acanthocephalans. Specimens of two species, i.e. Corynosoma australe and C. cetaceum, were collected from both host species. In sea lions, 78 out of 145 (37.9%) females of C. australe were gravid and the sex ratio was strongly female-biased. However, none of the 168 females of …

Can Sex Inversion Be Environmentally Induced?

1980

Among teleosts simultaneous hermaphroditism and spontaneous sex inversion (either protogyny or protandry) occur in many families that inhabit tropical and subtropical marine waters. The tooth-carp Rivulus marmoratus is unique among these in being self-fertilizing. Most studies are descriptive work on gonad histology and reproductive behavior. Experimental investigations are scanty and do not yet provide fruitful ideas that might help to understand what is occurring in a fish when it changes sex. Behavioral observations and experiments led to the hypothesis that in certain coral reef fish sex inversion may be under social control. The term sex inversion requires closer examination in order t…

Immunocompetence, developmental stability and wingspot size in the damselflyCalopteryx splendensL.

2000

Calopteryx splendens males exhibit a remarkable variation in wing pigmentation both within and between populations. In this study, we examined whether the wingspots of male C. splendens are related to male quality. We measured the nylon implant encapsulation rate for 85 males and found that males with larger wingspots had a faster encapsulation rate, indicating a better immunocompetence. We also found that the encapsulation rate was positively correlated with the density of haemocytes in the haemolymph. Another measurement of male quality, fluctuating asymmetry of wingspots, correlated negatively with the size of the wingspots. Males with asymmetrical wingspots also had lower encapsulation …

Invertebrate community responses to emerging water pollutants in Iberian river basins

2014

Abstract Chemical pollution is one of the greatest threats to freshwater ecosystems, especially in Mediterranean watersheds, characterized by periodical low flows that may exacerbate chemical exposure. Different groups of emerging pollutants have been detected in these basins during the last decade. This study aims to identify the relationships between the presence and levels of prioritary and emerging pollutants (pesticides, pharmaceutical active compounds—PhACs, Endocrine Disrupting Compounds EDCs and Perfluorinated Compounds—PFCs) and the invertebrate community in four Mediterranean basins: the Ebro, the Llobregat, the Jucar and the Guadalquivir. Structural (species composition and densi…

A revised model for lipid-normalizing δ13C values from aquatic organisms, with implications for isotope mixing models

2006

1. Stable isotope analyses coupled with mixing models are being used increasingly to evaluate ecological management issues and questions. Such applications of stable isotope analyses often require simultaneous carbon and nitrogen analyses from the same sample. Correction of the carbon isotope values to take account of the varying content of 13 C-depleted lipids is then frequently achieved by a lipid-normalization procedure using a model describing the relationship between change in δ 13 C following lipid removal and the original C:N ratio of a sample. 2. We evaluated the applicability of two widely used normalization models using empirical data for muscle tissue from a wide range of fish an…