Biodiversity & Conservation

MarLIN Glossary

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G

Gametophyte
The haploid sexual phase of a plant that exhibits an alternation of generations from which gametes are produced by mitosis (Lincoln et al., 1998).

Gametophytes
Plural of 'gametophyte'.

Gelbstoff
See 'yellow substance'.

Generation Time
The average period of time between reproduction of the parent generation and reproduction of the first filial generation or the average period of time between birth and reproduction (Lincoln et al., 1998).

Geology
The scientific study of the origin, history, structure and composition of the earth and its solid features.

Geomorphology
The branch of geology concerned with the structure, origin and development of topographical features of the earth's crust.

Globose
Spherical / ovoid / globular (Brusca, 1980).

Gnathopod
A leg-like appendage, specifically from a crustacean, that is at least partially modified to serve as a jaw (Hayward & Ryland, 1995).

Gnathopods
Plural of 'gnathopod'.

Gonochoristic
Having separate sexes (cf. 'hermaphroditic') (Barnes et al., 1993).

Grab
A mechanical bottom-sampling device which is lowered vertically from a stationary ship, for collection of sublittoral sediment and infauna (hand-grabs can also be used) (based on Holme & McIntyre, 1984) (cf. 'dredge', 'trawl').

Grain-size
See particle-size.

Grain-size Distribution
See particle-size distribution.

Granulometric Analysis
See 'granulometry'.

Granulometry
The quantitative measurement of the physical composition (grain-size) of a sediment (see also 'particle-size'; 'sedimentology').

Gravel
Sediment particles 4-16 mm in diameter, based broadly on Wentworth (1922), which may be formed from rock, shell fragments or maerl (based on Hiscock, 1990).

Grazers
1) Animals which: rasp benthic algae (or sessile animals, such as bryozoan crusts) from the substratum, or 2) animals which ingest phytoplankton from the water column by suspension-feeding (q.v.).

Gregarious
Living in groups or communities, growing in clusters.

Growth Form
The physical appearance and structure of an organism (cf. life form).

Groyne
A wall or jetty built out from a riverbank or seashore to combat the effects of longshore drift (q.v.) and control erosion.

Gulf Stream
A relatively warm ocean current flowing north-eastwards off the Atlantic coast of North America from the Gulf of Mexico. It reaches north-eastern Atlantic waters off Europe as the North Atlantic Drift.

Gully
A vertical space between two rock walls at least 0.5 m wide and 0.5 m or more in depth (based on Earll, 1992).

Gyre
A circular or spiral motion of fluid.

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Glossary references