Search results for "ocean"

Coastal New Particle Formation: A Review of the Current State-Of-The-Art

2005

Environmental Context.Atmospheric aerosols play an important role in determining the earth’s radiative budget, climate change and air quality levels. Much effort has been spent on quantifying the impact of aerosols on climate change; however, the largest gap in our knowledge relates to quantifying natural aerosol systems and the new particle formation process associated with these systems. The marine aerosol system is of particular interest due to the 70% ocean coverage of the earth’s surface. Coastal new particle formation events are though to be more frequent and of stronger intensity compared with open ocean events and thus have been studied in detail to identify possible processes lead…

Does population genetic structure support present management regulations of the northern shrimp (Pandalus borealis) in Skagerrak and the North Sea?

2014

AbstractPopulation structuring in the northern shrimp (Pandalus borealis) in the North Sea area (including Fladen and Skagerrak) was studied by microsatellite DNA analyses. Screening 20 sample locations in the open ocean and Skagerrak fjords for nine loci revealed low, but significant genetic heterogeneity. The spatial genetic structure among oceanic samples of Skagerrak and the eastern North Sea was weak and non-significant, consistent with the current management regime of one single stock. However, Skagerrak fjord samples generally displayed elevated levels of genetic differentiation, and significantly so in several pairwise comparisons with other fjords and oceanic samples. Although the …

Ecology of Cryptomonas at the chemocline of a karstic sulfate-rich lake

2001

In a study from October 1989 to January 1992, a dense population ofCryptomonas cf. erosa (maximum density 38 000 cells mL–1) consistently developed at the chemocline of Lake Arcas, central Spain,where sharp physical and chemical gradients occurred during stratification. This population developed following the establishment of vertical water stratification and declined when the lake was near autumnal mixis. Population growth in situ, attributable to photosynthetic adaptation to low light intensities rather than to phagotrophy, causes these algal maxima. The population densities and net growth rates of C. cf. erosa in situ were influenced by the coexisting phototrophic prokaryotes at the che…

Response to comments by Cardinale et al. on “Local cod (Gadus morhua) revealed by egg surveys and population genetic analysis after longstanding depl…

2019

INCOME AND QUALITY OF LIFE INFLUENCE ON CITIZENS' PARTICIPATION IN ACTIVITIES OF LOCAL GOVERNMENTS IN LATVIA

2018

The aim of the paper is to analyse the factors influencing the citizen participation in activities of local governments in relation to quality of life in Latvia. The use of the CLEAR model, elaborated by a group of British researchers under guidance of Gerry Stoker, shows the possibilities of participation and engagement of citizens based on theoretical aspects. Latvia, as a member state of the EU, needs to develop and to involve more citizens in different social activities, since it has comparatively small experience in democratic processes due to its past of 50 years being a part of another country — the Soviet Union. The opportunities to participate in the European Parliament’s election …

Megabenthos Underwater Video (MUV): a new device to evaluate species distribution in hard-to-reach marine areas

2021

A device, called Megabenthos Underwater Video (MUV), was designed and built for the counting and the size estimate of benthic organisms in hard-to-reach areas. Since 2014 Cassiopea andromeda, an invasive alien jellyfish in the Mediterranean Sea with benthic behavior, colonized a recreational harbor (Cala) of Palermo with a stable population. Studying the species distribution in this area with classical methods (such as visual census, ROV, etc.) was not applicable due to the large presence of obstacles (ropes, anchor cables, boats) and to dive difficulties in these types of area. The MUV was tested from 2017 to 2018 for the study of the spatial-temporal distribution of C. andromeda in the Ca…

Growth and production of three macrozoobenthic species in the Gulf of Riga, including comparisons with other areas

1999

Three soft-bottom stations in the southern part of the Gulf of Riga were studied during the period December 1993 to January 1995. The amphipods, Monoporeia affinis and Pontoporeia femorata, and the poychaete Marenzelleria viridis, were analysed for production, using the cohort growth method. Animals were also analysed for carbon and nitrogen content in a CHN-analyser. Based on size measurements, the quantitative data were divided into age-classes and the growth of each cohort was calculated first as wet weight and then converted into carbon and nitrogen content. Total annual production of each species was calculated as well as turnover ratios. The turnover ratio for Monoporeia affinis was e…

Predation as a factor mediating resource competition among rotifer sibling species

2004

The relevance of predation as a factor mediating the competitive interaction among ecologically very similar species is investigated by experimentally analyzing the effect of the copepod predator Diacyclops bicuspidatus odessanus on three sibling rotifer species belonging to the Brachionus plicatilis species complex. These rotifer species are similar in shape but show notable differences in body size. Predator and prey species co-occur in brackish waterbodies close to the Mediterranean coast of Spain. First, we characterized differential vulnerability of rotifers to predation. A consistent tendency of higher predation rates on smaller prey (i.e., smaller species and younger individuals) was…

Diel vertical migration by Daphnia longispina in a Spanish lake: Genetic sources of distributional variation

1995

Individuals of many zooplankton species undergo diel vertical migration in which they move toward the surface after sunset and return to deeper waters at dawn. However, even when vertical migration can be clearly demonstrated by mapping the distributions of individuals at noon and midnight, at any given time the population is usually scattered over ‘a broad range of depths. This paper focuses on a major potential source of the variance associated with depth distributions. We have used electrophoretic analysis of isozymes to identify “clones” of Daphnia longispina in a Spanish lake. In September 199 1, two clones constituted 5 5% of the individuals collected at noon and midnight on each oftw…

Population size estimation of larval coregonids in large lakes: Stratified sampling design with a simple prediction model for vertical distribution

2009

Abstract The lake-specific vertical distribution of larval coregonids was assessed annually in Finnish lakes by bongo net sampling. The effect of inter-annual and inter-lake variation in vertical distributions on population estimates of larval coregonids were analysed in 1999–2008. The vertical distribution of newly hatched vendace ( Coregonus albula (L.)) and European whitefish ( Coregonus lavaretus L. s.l.) larvae was analysed and high inter-annual and lake-specific variation in the larval vertical distribution was found. Generally, in both littoral and pelagic areas, larvae were aggregated near the water surface, mostly in the top 30 cm layer. We compared observed and predicted density e…