Search results for "ABUNDANCE"

Heterogenic aquatic vegetation promotes abundance and species richness of Odonata (Insecta) in constructed agricultural wetlands

2019

Effect of the abundance of three predominating copepod species on adequate sample volume and sample size in Bransfield Strait (Antarctic Peninsula) a…

1992

The effect on adequate sample size and sample volume of the abundances of three predominant copepod species, Metridia gerlachei, Calanus propinquus and Calanoides acutus, were studied in Bransfield Strait (Antarctic Peninsula) in the austral summer of 1988–1989 and waters north of the Weddell Sea in 1989–1990. Copepod abundances were higher in the area north of the Weddell Sea, with the exception of Metridia gerlachei, which was evenly distributed over both areas. Local (intra-station) patchiness was not found, indicating random distribution over small areas. In the assessment of inter-station variability in Bransfield Strait, with standard error of the mean set arbitrarily at 20% of the av…

Pre-Migratory Movements of Adult Montagu's HarriersCircus pygargus

2008

Pre-migratory and migratory movements of Montagu's Harrier Circus pygargus, a long-distance migrant, are poorly documented by ring recoveries and observations. In the present study, we tagged 10 adult Montagu's Harriers in NE Spain with satellite transmitters and tracked their movements until their arrival on the wintering grounds. To identify the end of the breeding season and the onset of the migration based on our satellite-telemetry data we developed and applied a statistical approach, defining the time period between these two events as the pre-migratory stage. We then compared habitat preferences during the breeding season and the pre-migratory stage. The duration of the pre-migratory…

Laboratory measurements and astronomical search for the HSO radical

2016

[Context] Despite the fact that many sulfur-bearing molecules, ranging from simple diatomic species up to astronomical complex molecules, have been detected in the interstellar medium, the sulfur chemistry in space is largely unknown and a depletion in the abundance of S-containing species has been observed in the cold, dense interstellar medium. The chemical form of the missing sulfur has yet to be identified.

Wood Ash Effects on Soil Fauna and Interactions with Carbohydrate Supply: A Minireview

2011

Wood ash effects on soil animals in a boreal forest ecosystem are reviewed focusing on recent results on interactive effects of wood ash and organic amendments, and laboratory microcosms as a tool to understand soil food webs are discussed. Loose wood ash can reduce the populations of enchytraeids, collembolans and mites, but increase nematode populations particularly in experimental laboratory ecosystems with little or no primary production. Recent studies indicate that the repressive effect on enchytraeids depends on carbon availability. Carbohydrate supply seemed to alleviate the negative wood ash effect on enchytraeid body size and abundance. The fact that carbon alleviated wood ash eff…

The toughest animals of the Earth versus global warming: Effects of long-term experimental warming on tardigrade community structure of a temperate d…

2021

Abstract Understanding how different taxa respond to global warming is essential for predicting future changes and elaborating strategies to buffer them. Tardigrades are well known for their ability to survive environmental stressors, such as drying and freezing, by undergoing cryptobiosis and rapidly recovering their metabolic function after stressors cease. Determining the extent to which animals that undergo cryptobiosis are affected by environmental warming will help to understand the real magnitude climate change will have on these organisms. Here, we report on the responses of tardigrades within a five‐year‐long, field‐based artificial warming experiment, which consisted of 12 open‐to…

Long-term abundance dynamics of coastal zooplankton in the Gulf of Riga

1998

The dynamics of three most abundant mesozooplankton species in the coastal zone of the Gulf of Riga — Bosmina longispina, Synchaeta baltica, Keratella quadrata — is analyzed to detect the regulating environmental factors. The only significant downward trend of species abundance was found for S. baltica in autumn. Statistically significant correlation was estimated only between the summer salinity and the abundance of B. longispina. K. quadrata though showed a negative correlation with summer salinity. The abundance of S. baltica had only nonsignificant correlations with the environmental factors. The abundance of coastal mesozooplankton species is determined by the combination of hydrologic…

Bacterial and phytoplankton responses to nutrient amendments in a boreal lake differ according to season and to taxonomic resolution

2011

Nutrient limitation and resource competition in bacterial and phytoplankton communities may appear different when considering different levels of taxonomic resolution. Nutrient amendment experiments conducted in a boreal lake on three occasions during one open water season revealed complex responses in overall bacterioplankton and phytoplankton abundance and biovolume. In general, bacteria were dominant in spring, while phytoplankton was clearly the predominant group in autumn. Seasonal differences in the community composition of bacteria and phytoplankton were mainly related to changes in observed taxa, while the differences across nutrient treatments within an experiment were due to chang…

Traditional and experimental floating fish aggregating devices in the Gulf of Castellammare (NW Sicily): Results from catches and visual observations

1999

Floating fish aggregating devices (FADs) have long been used to attract fish in NW Sicily since antiquity. Recently, a number of changes have been made to the type of material employed to construct FADs, with the aim of increasing their effectiveness. In this paper we compare the catches made at eight experimental floating FADs (polypropylene ropes frayed at the ends) with those obtained at eight traditional FADs in the Gulf of Castellammare. A total of 672 samples were collected during summer and autumn in 1995 and 1996 at the 16 FADs using a surrounding net. Visual observations of fishes associated with the FADs were also conducted to obtain qualitative information about the spatial distr…

Data from: Local cod (Gadus morhua) revealed by egg surveys and population genetic analysis after longstanding depletion on the Swedish Skagerrak coa…

2019

Dramatic and persistent reductions in Atlantic cod (Gadus morhua) are common in many coastal areas. While offshore cod stocks still were abundant and productive, the Swedish west coast showed signs of diminishing adult cod abundance at the beginning of the 1980s, where the local cod component was considered to be extirpated. To survey the present cod spawning activity and stock composition, we initiated egg trawling over two consecutive years (203 hauls in total) in combination with population genetic analyses (425 individually genotyped eggs). Here, we provide evidence of cod spawning at the Swedish Skagerrak coast, suggesting recolonization or that local cod has recovered from a nearly de…