Search results for "water temperature"

2017

Abstract. Mollusks record valuable information in their hard parts that reflect ambient environmental conditions. For this reason, shells can serve as excellent archives to reconstruct past climate and environmental variability. However, animal physiology and biomineralization, which are often poorly understood, can make the decoding of environmental signals a challenging task. Many of the routinely used shell-based proxies are sensitive to multiple different environmental and physiological variables. Therefore, the identification and interpretation of individual environmental signals (e.g., water temperature) often is particularly difficult. Additional proxies not influenced by multiple en…

Drivers of shell growth of the bivalve, Callista chione (L. 1758) - Combined it environmental and biological factors

2018

WOS:000426027100014; Seasonal shell growth patterns were analyzed using the stable oxygen and carbon isotope values of live-collected specimens of the bivalve Callista chione from two sites in the Adriatic Sea (Pag and Cetina, Croatia). Micromilling was performed on the shell surface of three shells per site and shell oxygen isotopes of the powder samples were measured. The timing and rate of seasonal shell growth was determined by aligning the delta O-18(shell)-derived temperatures so that the best fit was achieved with the instrumental temperature curve. According to the data, shells grew only at very low rates or not at all during the winter months, i.e., between January and March. Shell…

Long-Term Phytoplankton Dynamics in a Complex Temporal Realm

2019

AbstractFaced with an environment of accelerated change, the long-term dynamics of biotic communities can be approached to build a consistent and causal picture of the communities’ life. We have undertaken a 25-year monthly-sampling study on the phytoplankton of a meso-oligotrophic lake, paying attention to controlling factors of overall biomass (TB) and taxonomical group biomass (TGBs). Long-term series included decreased trends of TB and TGBs, and multi-scale periodicity. A decadal TB periodicity emerged related to nitrogen concentration and Cryptophytes. Annual periodicities were mainly related to air and water temperature controlling the abundance of Chlorophytes or Dinoflagellates. Int…

Distribution of Herbivorous Fish Is Frozen by Low Temperature.

2016

AbstractThe number of herbivores in populations of ectothermic vertebrates decreases with increasing latitude. At higher latitudes, fish consuming plant matter are exclusively omnivorous. We assess whether omnivorous fish readily shift to herbivory or whether animal prey is typically preferred. We address temperature as the key factor causing their absence at higher latitudes and discuss the potential poleward dispersion caused by climate changes. A controlled experiment illustrates that rudd (Scardinius erythrophthalmus) readily utilize plant matter at water temperatures above 20 °C and avoid its consumption below 20 °C. Field data support these results, showing that plant matter dominates…

Size does matter — the eco-evolutionary effects of changing body size in fish

2020

Body size acts as a proxy for many fitness-related traits. Body size is also subject to directional selection from various anthropogenic stressors such as increasing water temperature, decreasing dissolved oxygen, fisheries, as well as natural predators. Changes in individual body size correlate with changes in fecundity, behaviour, and survival and can propagate through populations and ecosystems by truncating age and size structures and changing predator–prey dynamics. In this review, we will explore the causes and consequences of changing body size in fish in the light of recent literature and relevant theories. We will investigate the central role of body size in ecology by first discu…

''Sex Difference In Open-water Ultra-swim Performance In the Longest Freshwater Lake Swim In Europe''

2013

Eichenberger, Evelyn | Knechtle, Beat | Knechtle, Patrizia | Ruest, Christoph A. | Rosemann, Thomas | Lepers, Romuald | Senn, Oliver; International audience; ''This study examined participation and performance trends in the 26.4-km open-water ultra-swim "Marathon Swim in Lake Zurich," Switzerland. A total of 461 athletes (157 women and 304 men) finished the race between 1987 and 2011. The mean age of the finishers during the studied period was 32.0 +/- 6.5 years for men and 30.9 +/- 7.2 years for women. The mean age of finishers and the age of winners increased significantly across years for both sexes (p 0.05). The swimming time performance remained stable (p > 0.05) for both sexes across …

Melosira distans var. tenella and Eunotia zasuminensis, two poorly known planktonic diatoms in Finnish lakes

1986

The occurrence and ecology of two poorly known planktonic diatoms, Melosira distans var. tenella (Nyg.) M.-B. Florin and Eunotia zasuminensis (Cabejsz.) Korner in central Finland is discussed. Both species have their maximum in late summer when water temperature is > 15°C and they prefer slightly acid water (pH < 7), low conductivity (less than 4 mS/m) and a moderate degree of dystrophy with C.O.D. 10–20 mg O2/l and water colour 60–120 mg Pt/1. Melosira distans var. tenella was found in ca. 80% of the central Finnish lakes studied, but it is not reported in previously published papers. Eunotia zasuminensis is rarer, but is, however, recorded in at least 22 lakes in central Finland.

Early-season river entry of adult Atlantic salmon: its dependency on environmental factors

2003

River entry of adult Atlantic salmon Salmo salar into the River Tornionjoki, monitored during three migration seasons (1997–1999) by horizontal split-beam hydroacoustics, started early in June when water temperature was c. 9° C and when the discharge varied between 1700 and 2000 m3 s−1. In 1997 and 1999, migration peaked during the latter half of June, 17 days after the peak flood, at water temperatures ranging from 11· 5 to 18·2° C. Few statistically significant correlations were observed between river entry and six measured environmental factors and those that were significant were not persistent over the years. The strongest correlation ( r = −0·60) was between the number of upstream mig…

Towards a local mass mortality of the Mediterranean orange coral Astroides calycularis (Pallas, 1766) in the Pelagie Islands Marine Protected Area (I…

2022

In late summer 2020, a widespread mortality event severely affected colonies of the Mediterranean endemic orange coral Astroides calycularis in the Pelagie Islands (Strait of Sicily, southern Mediterranean Sea). The degree of the mortality impact at seven study sites of the archipelago (five within the Pelagie Islands Marine Protected Area) was quantified by estimating the proportion of affected colonies in populations of A. calycularis. Five of the seven surveyed sites revealed a low degree of impact, but Punta Ruperta and Cala Creta (both on the island of Lampedusa) showed a medium impact with values of 32.3% and 30.5% of affected colonies respectively. The 2020 mortality event coincided …

Heat stroke risk for open-water swimmers during long-distance events.

2013

Open-water swimming is a rapidly growing sport discipline worldwide, and clinical problems associated with long-distance swimming are now better recognized and managed more effectively. The most prevalent medical risk associated with an open-water swimming event is hypothermia; therefore, the Federation Internationale De Natation (FINA) has instituted 2 rules to reduce this occurrence related to the minimum water temperature and the time taken to complete the race. Another medical risk that is relevant to open-water swimmers is heat stroke, a condition that can easily go unnoticed. The purpose of this review is to shed light on this physiological phenomenon by examining the physiological re…