Search results for "pelagic"
showing 10 items of 159 documents
Anisakis infections in lantern fish (Myctophidae) from the Arabian Sea: A dual role for lantern fish in the life cycle of Anisakis brevispiculata?
2018
Abstract Data on geographic distribution and life cycles of parasitic nematodes of the genus Anisakis in tropical oceanic regions are extremely scarce. Myctophids (lantern fishes) are a key component of mesopelagic trophic webs and could play a significant role in the transmission of Anisakis spp. in these regions. We examined Anisakis infections in a sample of 160 myctophids collected in three localities from the Indian Exclusive Economic Zone (Arabian Sea) in 2015–16. Due to the poor condition of fish, a combination of morphological data and molecular barcoding was used to identify myctophids. Of the 104 specimens that could be identified at least to genus level, 75 (72.1%) were assigned …
Deep-Sea Bioluminescence Blooms after Dense Water Formation at the Ocean Surface
2013
The deep ocean is the largest and least known ecosystem on Earth. It hosts numerous pelagic organisms, most of which are able to emit light. Here we present a unique data set consisting of a 2.5-year long record of light emission by deep-sea pelagic organisms, measured from December 2007 to June 2010 at the ANTARES underwater neutrino telescope in the deep NW Mediterranean Sea, jointly with synchronous hydrological records. This is the longest continuous time-series of deep-sea bioluminescence ever recorded. Our record reveals several weeks long, seasonal bioluminescence blooms with light intensity up to two orders of magnitude higher than background values, which correlate to changes in th…
Hydrography and food distribution during a tidal cycle above a cold-water coral mound
2022
Cold-water corals (CWCs) are important ecosystem engineers in the deep sea that provide habitat for numerous species and can form large coral mounds. These mounds influence surrounding currents and induce distinct hy- drodynamic features, such as internal waves and episodic downwelling events that accelerate transport of organic matter towards the mounds, supplying the corals with food. To date, research on organic matter distribution at coral mounds has focussed either on seasonal timescales or has provided single point snapshots. Data on food distribution at the timescale of a diurnal tidal cycle is currently limited. Here, we integrate physical, biogeochemical, and biological data throug…
Seasonal succession and growth in the plankton communities of the Gulf of Riga in relation to long-term nutrient dynamics
1999
To study temporal changes in phyto- and zooplankton in the Gulf of Riga monitoring data covering the period of 1972–1995 were analyzed. Changes in external nutrient supply have turned P limitation, during the 1980s, into the present deficiency of Si for the spring bloom. Contrary to depletion of the N and Si pools, the internal sources and sinks were responsible for input of P into the pelagic ecosystem in the 1990s. Restructuring of the nutrient pool reshaped the pelagic planktonic communities. Changes of the species composition and food-web relationships occurred. Till the 1990s, an increase of diatoms in the summer phytoplankton and an increase of herbivores in zooplankton took place. La…
First record of the enigmatic coleoid genus Longibelus from Sakhalin (Far East Russia): a contribution to our understanding of Cretaceous coleoid hab…
2021
AbstractA newly collected specimen of the enigmatic coleoid genus Longibelus is recorded from lower Turonian strata along the River Shadrinka in Sakhalin (Russian Far East). To date, this is the first record of Late Cretaceous coleoid cephalopods from the island and, in fact, from the entire Pacific coast of the Russian Federation. Lithological characteristics, coupled with published geochemical analyses (δ13C and Corg content), suggest the habitat of this coleoid taxon to have been the middle to outer (i.e. distal) shelf. Its provenance from the stratigraphical level that is known as the Scaphites Event, characterised by a mass occurrence of Scaphites and Yesoites, may be indicative of occ…
Note citotassonomiche sul genere Thapsia L. (Apiaceae)
2008
This study aims to clarify the taxonomic states and relations within the genus Thapsia from the Mediterranean area, with particular interest to the populations growing in Sicily. The results of morphological and karyological investigations on living plants, combined with herbarium surveys and literature data, allowed us to define an updated taxonomic profile of the genus Thapsia, with the description of a new species from the island of Lampedusa (SW Sicily), named T. pelagica. Moreover a new taxonomic combination is proposed for the populations of Peloritani Mts. (NE Sicily), which are here treated as subspecies messanensis of T. garganica.
Biogenic methane contributes to the food web of a large, shallow lake
2013
Summary Biogenic methane as an alternative carbon and energy source for freshwater organisms has been receiving increasing attention, but the phenomenon is still poorly understood for shallow lakes. We measured the carbon and nitrogen stable isotope signatures (δ13C, δ15N) for key groups of pelagic and benthic organisms, including crustacean zooplankton, chironomid larvae, young-of-the-year and adult fish, to assess whether biogenic methane contributes to pelagic and benthic food webs in a large, shallow lake, Lake Vortsjarv, Estonia. In the southern part of the lake, covered by macrophytes, crustacean zooplankton showed strong seasonal variation of δ13C, with the lowest values occurring in…
Prevalence of heterotrophic methylmercury detoxifying bacteria across oceanic regions
2022
10 pages, 4 figures, 1 table, supporting information https://doi.org/10.1021/acs.est.1c05635
Modelling biogeochemical processes in sediments from the north western Adriatic Sea: response to enhanced POC fluxes
2017
Abstract. This work presents the result of a study carried out in the north-western Adriatic Sea, by combining two different types of biogeochemical models with field sampling efforts. A longline mussel farm was taken as a local source of perturbation to the natural POC downward flux. This flux was first quantified by means of a pelagic model of POC deposition coupled to sediment traps data, and its effects on sediment bioirrigation capacity and OM degradation pathways were investigated by constraining an early diagenesis model, linked to new data in sediment porewaters. The measurements were performed at stations located inside and outside the area affected by mussel farm deposition. Model…
Potential for large-bodied zooplankton and dreissenids to alter the productivity and autotrophic structure of lakes.
2014
While limnological studies have emphasized the importance of grazers on algal biomass and primary production in pelagic habitats, few studies have examined their potential role in altering total ecosystem primary production and it's partitioning between pelagic and benthic habitats. We modified an existing ecosystem production model to include biotic feedbacks associated with two groups of large-bodied grazers of phytoplankton (large-bodied zooplankton and dreissenid mussels) and estimated their effects on total ecosystem production (TEP), and the partitioning of TEP between phytoplankton and periphyton (autotrophic structure) across large gradients in lake size and total phosphorus (TP) co…