H
HABITAT COMPLEXITY
Selene Ortiz-Burgos
Facultad de Estudios Superiores Zaragoza, Universidad
Nacional Autónoma de México (UNAM), Delegación
Iztapalapa, DF, México
Synonyms
Architectural complexity; Habitat architecture; Habitat
heterogeneity; Substrate heterogeneity; Topographical
complexity
Definitions
Krebs (1994) has defined a habitat as any part of the biosphere where a particular species can live, either temporarily or permanently.
Complexity is defined as one aspect of habitat quality
that is thought to influence the size, structure, distribution,
and stability of populations.
Habitat complexity refers to the level or strength of
interaction between a species and its environment.
Introduction
In estuarine ecosystems, habitat complexity is one of the
most important factors structuring biotic assemblages.
It is frequently an important variable affecting species
abundance and diversity. Habitats with high habitat complexity typically support more species and individuals
than nearby less complex habitats. Identifying the key
aspects and spatial scales of habitat complexity is critical
to understanding the ecology and conservation of
a range of communities (Gratwick and Speight, 2005;
Kovalenko et al., 2012).
Description habitat complexity
Habitat complexity has been described in terms of structural components. Most authors only examine one or two
variables out of at least six that are recognized
(Gratwicke and Speight, 2005). These six include the following: (1) topographic complexity or rugosity of the substratum; (2) substratum diversity; (3) variety of refuge
hole sizes; (4) vertical relief or height of substratum architecture; (5) percentage live cover, including corals and
seagrasses; and (6) percentage hard substratum.
Topographic complexity or rugosity of the
substratum
This component can be measured in several ways. The
most frequently used measurement of reef surface complexity is rugosity. This is most commonly measured by
the chain-and-tape method whereby a ratio of the length
of a chain draped across the reef surface to the linear
stretched length is calculated. This ratio, hereafter referred
to as linear rugosity, provides a rugosity measurement
(index) that has been used to determine its relationship
with fish abundance, biomass, species richness, and species diversity indices (Walker et al., 2009).
Substratum diversity
The substratum diversity is the percentage cover of different substrata on a 10-m transect and is measured from
stereophotographs. The number of centimeters of the tape
measure covering each substratum type, expressed as
a percentage of the total transect length, gives an unbiased
estimate of their cover. Hard and soft corals are classified
into recognizable taxonomic units for this analysis.
A second measure of the complexity of the substratum
along the transects, the Shannon-Wiener index (H’), is
calculated from the percentage cover data of different substratum types from each depth to give a measure of biological diversity (Roberts and Ormond, 1987).
M.J. Kennish (ed.), Encyclopedia of Estuaries, DOI 10.1007/978-94-017-8801-4,
© Springer Science+Business Media Dordrecht 2016
HABITAT COMPLEXITY
Selene Ortiz-Burgos
Facultad de Estudios Superiores Zaragoza, Universidad
Nacional Autónoma de México (UNAM), Delegación
Iztapalapa, DF, México
Synonyms
Architectural complexity; Habitat architecture; Habitat
heterogeneity; Substrate heterogeneity; Topographical
complexity
Definitions
Krebs (1994) has defined a habitat as any part of the biosphere where a particular species can live, either temporarily or permanently.
Complexity is defined as one aspect of habitat quality
that is thought to influence the size, structure, distribution,
and stability of populations.
Habitat complexity refers to the level or strength of
interaction between a species and its environment.
Introduction
In estuarine ecosystems, habitat complexity is one of the
most important factors structuring biotic assemblages.
It is frequently an important variable affecting species
abundance and diversity. Habitats with high habitat complexity typically support more species and individuals
than nearby less complex habitats. Identifying the key
aspects and spatial scales of habitat complexity is critical
to understanding the ecology and conservation of
a range of communities (Gratwick and Speight, 2005;
Kovalenko et al., 2012).
Description habitat complexity
Habitat complexity has been described in terms of structural components. Most authors only examine one or two
variables out of at least six that are recognized
(Gratwicke and Speight, 2005). These six include the following: (1) topographic complexity or rugosity of the substratum; (2) substratum diversity; (3) variety of refuge
hole sizes; (4) vertical relief or height of substratum architecture; (5) percentage live cover, including corals and
seagrasses; and (6) percentage hard substratum.
Topographic complexity or rugosity of the
substratum
This component can be measured in several ways. The
most frequently used measurement of reef surface complexity is rugosity. This is most commonly measured by
the chain-and-tape method whereby a ratio of the length
of a chain draped across the reef surface to the linear
stretched length is calculated. This ratio, hereafter referred
to as linear rugosity, provides a rugosity measurement
(index) that has been used to determine its relationship
with fish abundance, biomass, species richness, and species diversity indices (Walker et al., 2009).
Substratum diversity
The substratum diversity is the percentage cover of different substrata on a 10-m transect and is measured from
stereophotographs. The number of centimeters of the tape
measure covering each substratum type, expressed as
a percentage of the total transect length, gives an unbiased
estimate of their cover. Hard and soft corals are classified
into recognizable taxonomic units for this analysis.
A second measure of the complexity of the substratum
along the transects, the Shannon-Wiener index (H’), is
calculated from the percentage cover data of different substratum types from each depth to give a measure of biological diversity (Roberts and Ormond, 1987).
M.J. Kennish (ed.), Encyclopedia of Estuaries, DOI 10.1007/978-94-017-8801-4,
© Springer Science+Business Media Dordrecht 2016