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43,004
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"Estuaries"
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Morphometrics, Growth and Condition of the Invasive Bivalve IRangia cuneata/I during Colonisation of the Oder Estuary
The aim of this study was to determine the biological, morphometric, and shape characteristics of the bivalve Rangia cuneata in the initial phase of colonisation. A total of 504 specimens were caught for the study. Their average length was 31.06 mm (range 12.7–43.2 mm) and weight 6.0 g (0.5–15.3 g). The population was dominated by individuals of 25–30 mm and 30–35 mm in length and the age of 3+ and 4+. The standard major axis regression for measurable traits describing shell cross-section indicate the allometric nature of growth for most parameters. Elongation and convexity indices by age group indicate a change in the shell shape as it becomes more elongated and convex in individuals that have already reached sexual maturity. The collected specimens were of larger sizes compared to other Baltic populations of the species, and similar in size to populations found in the neighboring Pomeranian Bay. The increase in length of R. cuneata in the Oder estuary is smaller compared to the species native sites, probably due to the lower water temperature in the study area. Considering the invasive potential of R. cuneata, it seems necessary to monitor closely its population and distribution in the estuary of Western Baltic.
Journal Article
First Record of the Alien Tintinnid Ciliate IRhizodomus tagatzi/I Strelkow and Wirketis 1950 in the Adriatic Sea
The tintinnid ciliate Rhizodomus tagatzi has spread rapidly in recent decades in neritic areas of the Mediterranean and adjacent seas, where it is classified as a non-indigenous species. The present study documents the first finding of the species in the Adriatic Sea, in the transitional waters of the Neretva River estuary. Zooplankton material was collected with 5 L Niskin bottles in three layers (1, 5 and 7 m) at two stations, at the mouth of the Neretva River and 16 km upstream, in the period from May 2022 to January 2023. In addition to the morphological characteristics of R. tagatzi, we discuss the state and variability of the populations based on the abundance of the species and the influence of abiotic environmental factors (temperature and salinity) and possible pathways of entry into the Adriatic Sea. The maximum abundance of R. tagatzi in the Neretva River estuary of ~2 × 10[sup.3] cells L[sup.−1] is among the highest in the Mediterranean Sea, and the species has a significant contribution to the tintinnid community (>80%), indicating successful establishment of the population in the estuary and intense influence on ecosystem functioning until the strong river flow completely displaces the wedge from the seabed. Statistical methods confirm the differences between stations in the total abundance of tintinnids and differences in their vertical distribution at the upstream station.
Journal Article
Ecology of salmonids in estuaries around the world : adaptations, habitats, and conservation
\"For centuries, biologists have marvelled at how anadromous salmonids--fish that pass from rivers into oceans and back again--survive as they migrate between these two very different environments. Yet, relatively little is understood about what happens to salmonid species (including salmon, steelhead, char, and trout) in the estuaries where they make this transition from fresh to saltwater. This book, written by one of the world's foremost experts on the ecology of salmonids, explains the critical role estuaries play in salmonid survival and recovery.\"-- Provided by publisher.
Book
Corrigendum: Morphometric distribution of Java eel Anguilla sp. caught from different estuaries of Central Java (2020 IOP Conf. Ser.: Earth Environ. Sci. 750 012042)
Abstract
Please see Article PDF for corrigendum text.
Journal Article
Spatial distribution and impact of the gill-parasitic Mazocraes alosae
Are the distribution of Mazocraes alosae and its impact on the host similar between Alosa alosa and A. fallax according to their resemblances? Parasites were numbered on each gill of shads sampled in North-East Atlantic coastal waters and connected rivers. Their impact on host condition was measured using girth, gonado-somatic ratio, C/N ratio, and Fulton's K. Prevalence and mean intensity of M. alosae were significantly higher for A. alosa than for A. fallax, including in sympatric conditions. The mean intensity varied among sites whatever fish species; it was higher in coastal-estuarine versus fresh waters only for A. fallax. The distribution of M. alosae was aggregated in the host population whatever species. At the host individual level, some gills (second and third for A. alosa, second for A. fallax) were significantly more inhabited than others, probably in relation with larger water volumes flowing on these gills and mazocraeid sedentary lifestyle. Despite high prevalence and intensity, no negative impact of M. alosae was demonstrated on the host condition whatever the index considered. Our study underlines the major occurrence of M. alosae on shads and the potential use of such benign parasite as biological tag to discriminate closely related host species.
Journal Article
Seasonal Water Column NH.sub.4.sup.+ Cycling Along a Semi-arid Sub-tropical River-Estuary Continuum: Responses to Episodic Events and Drought Conditions
River-estuary continuums represent a dynamic range of environmental conditions in aquatic ecosystems, providing an ideal gradient for understanding changes in nitrogen (N) cycling. We measured rates of ammonium (NH.sub.4.sup.+) cycling, including uptake and regeneration, in the water column of upper river, lower river, and estuary sites. This 1-year study encompassed periods of flood and drought, in a coastal catchment of south Texas. Low NH.sub.4.sup.+ concentrations and frequently balanced net NH.sub.4.sup.+ fluxes suggest minimal N cycling, but these measurements alone did not reveal the patterns of water column NH.sub.4.sup.+ uptake and regeneration in the river and estuarine systems. Rapid turnover of NH.sub.4.sup.+ supported productive estuaries, particularly during periods of droughts when riverine sources of NH.sub.4.sup.+ were minimal. However, NH.sub.4.sup.+ demand declined during storms across the river-estuary continuum, and regeneration rates were high, especially in the rivers. Most research in rivers has focused on benthic or whole-system dynamics, but our data demonstrate that active NH.sub.4.sup.+ cycling also occurs in isolated river water columns. Lower river sites were hotspots of NH.sub.4.sup.+ cycling on the landscape. Continued studies across river-estuary continuums are needed to enhance our understanding of aquatic systems and improve our ability to manage nutrients in the face of increased anthropogenic pressures and a changing climate.
Journal Article