to influence physical, biological, or socioeconomic processes related to living marine resources” (Seaman and
Jensen, 2000, 5). While this definition is directed toward
the marine environment, a few modifications to include
“estuarine and freshwater” resources make it applicable
to the estuarine environment as well. Also, it should be
noted that artificial reefs are not always “deployed purposefully” as “accidental” deployments of ships or other
objects sunk by storms, acts of war, or other episodic
events can also create submerged structure that function
under the banner of artificial reefs. Additionally,
a broader appreciation of the utility of artificial reefs
would certainly make them useful to disciplines which
are not mutually exclusive. Thus, artificial reefs can
simultaneously influence physical, biological, and/or
socioeconomic processes.
Introduction
Artificial reefs have likely been deployed for the purposes
of enhancing fishing for millennia. Most probably, fish
associated with naturally occurring debris in rivers and
lakes were recognized early in human history as functioning as preferred structure for some fish species. It would
have been intuitive to help Mother Nature along by
deploying similar-looking, natural structures in aquatic
habitats to further enhance fishing. The modern impetus
for artificial reef seems to have come from the congregations of reef fishes observed around sunken ships and
downed warplanes resulting from sea battles during the
World War II in the Pacific Ocean. For example, Chuuk
(Truk) Lagoon in Micronesia, where 32 merchant ships
and 249 aircraft were sunk, has become a diver’s “paradise” since the early 1970s (Trumbull, 1972). The advent
and popular use of scuba by the general populace since
the late 1950s helped the general recognition that artificial
reefs were a “good thing” when it came to fisheries, but
there were few data and studies directed toward truly
establishing the verifiable reasons for their deployment.
Of late, artificial reefs have garnered attention by natural
resource managers, aquatic scientists, and the fishing public to improve fishing and fisheries around the world. The
popular mantra is that “more reefs will mean more fish”
without regard for the effects of these structures on other
natural processes. Lastly, the “proof” of artificial reefs as
an effective management tool is wanting, largely owing
to the lack of scientifically valid opportunities to test various hypotheses.
Kinds of artificial reefs
Artificial reefs are generally of two basic types: benthic
(i.e., located on the majority of mid-water/surface
Fig. 1). The majority of mid-water and surface reefs serves
as fish-aggregating device (FADs) and is directed primarily at the pelagic and epipelagic game fishes in coastal
areas. Benthic reefs have been the subject of much effort
in design and planning. A broad variety of structure have
been used in artificial reefs, but generally they can be
considered as either structure of opportunity (i.e., made
of refuse materials) or designed and engineered specifically to serve as artificial reefs. Structure of opportunity
include (but are not limited to) ships, automobiles, and
other vehicles (e.g., railroad cars and airplanes), derelict
oil and gas platforms, bridge rubble, remnant construction
materials (e.g., broken sewer pipe), scrap metal of various
composition and gauges, white goods (refuse household
appliances such as washing machines, stoves, and refrigerators), vehicle tires, fiberglass materials, porcelain, and
any materials considered dense enough to sink and withstand some degree of wave action or current surge.
Engineered structures can run the gamut of all of the
above but are generally composed of structures thought
to have a longer life span (durability) and greater stability
(density) than reefs composed of structures of opportunity.
Engineered structures are most often composed of concrete, concrete and rock aggregate, and heavy gauge steel.
Generally, artificial reefs are deployed as modules or
units of a size and shape readily transportable and deployable. These modules are then organized into sets of two or
more modules, and the sets are often organized into
groups. Lastly, the groups of sets and modules comprise
the entire reef complex that may be of considerable extent,
covering several kilometers (Grove et al., 1991).
Locations of artificial reefs
Artificial reefs have been deployed in virtually every
aquatic ecosystem from freshwater streams, rivers, ponds,
and lakes to estuaries, fjords, bays, and the open ocean
(both near coastal and far offshore). The substrate type
upon which the reefs are deployed is an important consideration, as some substrates are easily eroded or scoured,
and the reef can become quickly covered so as to become
nonfunctional as an artificial reef.
Position of the reef in proximity to other biota is often
a deployment consideration to facilitate colonization by
juveniles, adults, or prey items. Depending on the
intended function of the reef, positioning the reef to facilitate (or prohibit) access by users is often a consideration
as well.
Functions of artificial reefs
Artificial reefs can have many functions via the ecosystem
services they provide. Often a chief function is to enhance
fisheries for fishing opportunities for both the commercial
and recreational fishing public. Environmentally, artificial
reefs can serve to mitigate damage to natural areas, serve
to enhance biotic community diversity, or fulfill other
goals of resource managers. Artificial reefs have been
used as objects to deter various fishing activities such as
the protection of seagrass beds from trawling (Fabi and
Spagnolo, 2011). Recreationally, artificial reefs can serve
as scuba and snorkeling sites, especially to enhance areas
void of “interesting substrate” or as alternative dive sites
to protect natural areas from potential damage by divers.
Artificial reefs can provide a substrate to allow settling
38
ARTIFICIAL REEF
Jensen, 2000, 5). While this definition is directed toward
the marine environment, a few modifications to include
“estuarine and freshwater” resources make it applicable
to the estuarine environment as well. Also, it should be
noted that artificial reefs are not always “deployed purposefully” as “accidental” deployments of ships or other
objects sunk by storms, acts of war, or other episodic
events can also create submerged structure that function
under the banner of artificial reefs. Additionally,
a broader appreciation of the utility of artificial reefs
would certainly make them useful to disciplines which
are not mutually exclusive. Thus, artificial reefs can
simultaneously influence physical, biological, and/or
socioeconomic processes.
Introduction
Artificial reefs have likely been deployed for the purposes
of enhancing fishing for millennia. Most probably, fish
associated with naturally occurring debris in rivers and
lakes were recognized early in human history as functioning as preferred structure for some fish species. It would
have been intuitive to help Mother Nature along by
deploying similar-looking, natural structures in aquatic
habitats to further enhance fishing. The modern impetus
for artificial reef seems to have come from the congregations of reef fishes observed around sunken ships and
downed warplanes resulting from sea battles during the
World War II in the Pacific Ocean. For example, Chuuk
(Truk) Lagoon in Micronesia, where 32 merchant ships
and 249 aircraft were sunk, has become a diver’s “paradise” since the early 1970s (Trumbull, 1972). The advent
and popular use of scuba by the general populace since
the late 1950s helped the general recognition that artificial
reefs were a “good thing” when it came to fisheries, but
there were few data and studies directed toward truly
establishing the verifiable reasons for their deployment.
Of late, artificial reefs have garnered attention by natural
resource managers, aquatic scientists, and the fishing public to improve fishing and fisheries around the world. The
popular mantra is that “more reefs will mean more fish”
without regard for the effects of these structures on other
natural processes. Lastly, the “proof” of artificial reefs as
an effective management tool is wanting, largely owing
to the lack of scientifically valid opportunities to test various hypotheses.
Kinds of artificial reefs
Artificial reefs are generally of two basic types: benthic
(i.e., located on the majority of mid-water/surface
Fig. 1). The majority of mid-water and surface reefs serves
as fish-aggregating device (FADs) and is directed primarily at the pelagic and epipelagic game fishes in coastal
areas. Benthic reefs have been the subject of much effort
in design and planning. A broad variety of structure have
been used in artificial reefs, but generally they can be
considered as either structure of opportunity (i.e., made
of refuse materials) or designed and engineered specifically to serve as artificial reefs. Structure of opportunity
include (but are not limited to) ships, automobiles, and
other vehicles (e.g., railroad cars and airplanes), derelict
oil and gas platforms, bridge rubble, remnant construction
materials (e.g., broken sewer pipe), scrap metal of various
composition and gauges, white goods (refuse household
appliances such as washing machines, stoves, and refrigerators), vehicle tires, fiberglass materials, porcelain, and
any materials considered dense enough to sink and withstand some degree of wave action or current surge.
Engineered structures can run the gamut of all of the
above but are generally composed of structures thought
to have a longer life span (durability) and greater stability
(density) than reefs composed of structures of opportunity.
Engineered structures are most often composed of concrete, concrete and rock aggregate, and heavy gauge steel.
Generally, artificial reefs are deployed as modules or
units of a size and shape readily transportable and deployable. These modules are then organized into sets of two or
more modules, and the sets are often organized into
groups. Lastly, the groups of sets and modules comprise
the entire reef complex that may be of considerable extent,
covering several kilometers (Grove et al., 1991).
Locations of artificial reefs
Artificial reefs have been deployed in virtually every
aquatic ecosystem from freshwater streams, rivers, ponds,
and lakes to estuaries, fjords, bays, and the open ocean
(both near coastal and far offshore). The substrate type
upon which the reefs are deployed is an important consideration, as some substrates are easily eroded or scoured,
and the reef can become quickly covered so as to become
nonfunctional as an artificial reef.
Position of the reef in proximity to other biota is often
a deployment consideration to facilitate colonization by
juveniles, adults, or prey items. Depending on the
intended function of the reef, positioning the reef to facilitate (or prohibit) access by users is often a consideration
as well.
Functions of artificial reefs
Artificial reefs can have many functions via the ecosystem
services they provide. Often a chief function is to enhance
fisheries for fishing opportunities for both the commercial
and recreational fishing public. Environmentally, artificial
reefs can serve to mitigate damage to natural areas, serve
to enhance biotic community diversity, or fulfill other
goals of resource managers. Artificial reefs have been
used as objects to deter various fishing activities such as
the protection of seagrass beds from trawling (Fabi and
Spagnolo, 2011). Recreationally, artificial reefs can serve
as scuba and snorkeling sites, especially to enhance areas
void of “interesting substrate” or as alternative dive sites
to protect natural areas from potential damage by divers.
Artificial reefs can provide a substrate to allow settling
38
ARTIFICIAL REEF