410
cal and/or electronic detection apparatus. It allows simul-
taneous multiparametric analysis of the physical and/or
chemical characteristics of up to thousands of particles
per second.
Fluorescent in situ hybridization (FISH) Technique used
to detect and localize the presence or absence of specific
DNA sequences on chromosomes. FISH uses fluores-
cent probes that bind to only those parts of the chromo-
some with which they show a high degree of sequence
complementarity.
Fluorochrome Any of a group of fluorescent dyes (chemi-
cal entity, such as a molecule or group) used to label bio-
logical material.
Frequency of Visibly Infected Cells (FVIC) Proportion of
prokaryotic cells containing viral particles.
Frustule the siliceous skeleton of diatoms.
Fungi, true fungi, fungi True fungi (or fungi) are eukary-
otic organisms presenting a chitin cell wall. All these
organisms are classified as a kingdom, Fungi.
GSI Gonado Somatic Index: In percent. It is the report of
the weight of gonads on the weight of the fish.
Gas lake outburst or limnic eruption massive release of
gases (mainly CO 2 , CH 4 ) from the monimolimnion (deep
part of a permanently stratified lake), which was recog-
nized as a type natural hazard since the Lake Monoun
(1984) and Lake Nyos (1986) disasters. The catastrophic
gas outburst may be provoked by a sublacustrine or aerial
landslide, which itself may be triggered by an earthquake.
Another way to destabilize the water column leading to
the massive gas escape is when the waters are supersatu-
rated in gases: when the ebullition process is initiated, the
resulting destabilization of waters is irreversible and lead
to the massive escape.
Geomythology perception of geological hazards by local
people, as transmitted across generations through myths,
legends, rites or representations.
Geothermal process Process relating to the Earth’s interior
heat.
Granitic basement This is the basement of the French
Massif central, comprising a widespread, flattened ero-
sional surface, which is the result of the long- lasting ero-
sion of the hercynian mountain range. The majority of
rocks are granites and gneisses. The volcanic massifs lie
directly on the erosional surface.
Gravity cores sedimentary cores acquired by dropping a
core barrel with a weight on the lake floor.
Gregorius of Tours Saint Gregorius (c 538 – 594) is a
Gallo-Roman historian and Bishop of Tours, born in Urbs
Arverna –now Clermont. In his chronicles he mentioned
several extra-ordinary events as the Tauredunum cata-
strophic event which destroyed Geneva (proven in 2012
to be a lake tsunami). It is here hypothesized that two of
his stories concern past pagan lake cult at Pavin and a
catastrophic overspill near 590 (Hermit Caluppa’dragons
encounters).
Halide ion A singlet halogen atom, which is an anion with
a charge of −1.
Halogen A family of chemical elements that comprises
astatine, fluorine, chlorine, bromine and iodine.
Halogenase One of a group of enzymes that halogenate
organic substrates using oxygen and a halide ion (Cl−,
Br−, or I−).
Haloperoxidase One of a group of enzymes that haloge-
nates organic substrates using hydrogen peroxide and a
halide ion (Cl−, Br−, or I−). Haloperoxidases contain
either heme or vanadium.
Heteroaromatic Having the characteristics of an aromatic
compound whilst having at least one non- carbon atom in
the ring.
Heterotrophic flagellates free-living protozoa, their move-
ment and feeding mainly through flagella, heterotrophic
way to get food or energy.
Hotspot microenvironment a microscale spot with high
microbial activity.
Human sacrifices mentioned at maar-lakes in some pre-
christian lake cults legends and stories.
Hydrogen Index (HI) amount of hydrocarbons released
during pyrolysis in Rock-Eval analyzer, normalized to
TOC (unit expressed in mg HC.g−^1 TOC).
Hydrological cycle The natural sequence through which
water passes into the atmosphere as water vapor, pre-
cipitates to earth in liquid or solid form, and ultimately
returns to the atmosphere through evaporation.
Hydrostatic pressure The pressure exerted by a fluid at
equilibrium at a given point within the fluid, due to the
force of gravity. Hydrostatic pressure increases in propor-
tion to depth.
Hyperhalophiles type of extremophiles which includes pro-
karyotes and some eukaryotes (algae and fungi) that live in
environments characterized by very high salt concentrations.
Hyperthermophiles subset of extremophile microorgan-
isms that thrive in extremely hot environments (80 °C and
above) such as hot springs.
Hypolimnetic relating to hypolimnion (see hypolimnion).
Hypolimnion is the dense, bottom layer of water in a ther-
mally-stratified lake. It is the layer that lies below the
thermocline.
IRSTEA National institute of research in sciences and tech-
nologies for the environment and the agriculture.
Iron isotope composition although iron has four stable iso-
topes (^54 Fe,^56 Fe,^57 Fe,^58 Fe), only two isotopes are gener-
ally used to define the isotope composition of a specific
sample. The isotope composition is expressed in the δ
notation as:δ^56 Fe = [(^56 Fe/^54 Fe)sample/(^56 Fe/^54 Fe)standard −1] × 1000Glossary