Traditional methods
Qualitative ecological information has been obtained for megabenthos in the polar seas, as
elsewhere, by the traditional use of trawling and dredging techniques (e.g. Galeron et al.
1992). However, as a result of the relative inaccessibility of these environments there are
few quantitative data with sufficient spatial and temporal coverage to yield a meaningful
description of community structure (Lauerman et al. 1996). In particular the quantification
of megabenthos has proven difficult as, depending on the species, they may be sparsely
distributed, fragile or highly mobile.
Barthel and Gutt (1992) state that although dredge hauls in deeper water normally provide
the material necessary for species identification, organic substance determination and
coarse dominance and abundance information much valuable biological information is lost
that could be obtained from underwater photographs such as habitat preference, association
with other (especially motile) fauna and small and medium scale patchiness. Hedgpeth
(1971) shows that a combination of the two approaches results in a better appreciation of
the true situation.
A number of previous, mostly deep-sea studies have shown that biomass and abundance
calculations for macro- and megafauna based on phototransects yield much higher values
Photography
History of use
The first photographs taken of the benthic environment were of the sunlit Mediterranean
seabed in 1893 (Boutan 1893), after which followed an explosion in the use of underwater
photography in shallow seas, opening up this environment to a wider public (e.g. Cousteau
and Dugan 1963). Deep-sea photography started in the 1940s at the Woods Hole
Oceanographic Institution by a group led by Maurice Ewing (Ewing et al. 1946; Ewing et
al. 1967). The cameras developed by this group photographed the sea floor when triggered
by contact with the bottom (Thorndike 1959). Schenck and Kendall (1954) discuss
underwater photography in these early days and provide a bibliography of the older
literature.
Whilst there were many good deep-sea photographs available between the 1950s and early
1970s few biologists studied them, often as no corresponding samples of animals were
taken, making identification difficult (Fell 1967). However, there were a few notable
exceptions who carried out detailed investigations using seabed photography during this
period (Vevers 1951; Fell 1962; Clark 1963; Marshall and Bourne 1964; Hersey 1967;
Photographic techniques
The development of photographic techniques has enabled quantitative data to be obtained
on the spatial and temporal abundances and distribution of megabenthic fauna. On a
smaller scale from surveys taken by free-fall cameras ‘bounced’ along the seabed (Gage
and Tyler 1991) or deployed on the seabed for long periods, taking photographs at regular
intervals e.g. ‘Bathysnap’ (Lampitt and Burnham 1983). On a larger scale photographic
surveys have been made by towed camera sleds which may be towed over the sediment
(e.g. Rice et al. 1982; Cailliet et al. 1999) or using acoustic telemetry, fly at a set altitude
e.g. Wide Angle Survey Photography (WASP) system (Bett 2001); manned submersibles
(Grassle et al. 1975); Remotely Operated Vehicles (ROV) (Starmans et al. 1999) and with
the development of Autonomous Underwater Vehicles (AUV) e.g. Autosub (Babb 1993)
previously inaccessible environments can be sampled.
Photographic techniques as tools for ecological assessment
Freefall cameras
Freefall camera systems were the first photographic tools for deep-water ecological
assessment (Hersey 1967; Heezen and Hollister 1971). They have been used extensively in
more recent models typically depicting a small area of seabed and allowing identification
of organisms down to 1mm (e.g. Piepenburg and Schmid 1997). They provide a
quantitative quadrat type sample although the area covered, even by systems bounced
along the seabed is typically very small. These camera systems have been important in the
study of all deep-sea environments (Hersey 1967; Heezen and Hollister 1971; Menzies et
al. 1973; Langton and Uzmann 1989; Gutt and Starmans 1998; Gutt et al. 1999). Freefall
cameras have also been used to get the first impressions of life under ice shelves (Lipps et
al. 1979; Dayton and Kooyman 1985) although these studies are based on very few often
unclear photographs. These systems, equipped with high resolution 70mm cameras have
been used extensively in the polar regions to increase the information available on these
important megafaunal communities (Piepenburg and Schmid 1996b; Piepenburg and
Schmid 1997; Gutt and Starmans 1998; Gutt and Starmans 2001; Piepenburg et al. 2001).
Time-lapse cameras
Time-lapse cameras, typically deployed on benthic landers provide a quantitative
photographic sample of a small area of benthos over a typically long time period (Bett
2003). Previously unknown important temporal variations in megabenthic abundance have
been discovered using this method, for example using the SOC ‘Bathysnap’ time-lapse
camera Bett et al. (2001) reported a radical change in the abundance and activity of
Towed cameras
Towed camera systems provide a quantitative picture of a relatively large area of the
benthic environment and can be used for transect type biological studies (Rice et al. 1982;
Holme and McIntyre 1984; Wakefield and Smithey 1989; Hecker 1990; Christiansen and
Thiel 1992). They typically lack the resolution of the freefall cameras although good
results have been obtained from sledge type cameras. Towed camera platforms are used
particularly for geological studies (Kleinrock et al. 1992) and were instrumental in the
location of hydrothermal vents (Lonsdale 1977b; Lonsdale 1977a), biological studies are
less common. Most studies concentrate on the distribution and abundance of megafaunal
organisms for example in the abyssal northeast Pacific (Lauerman et al. 1996), towed
camera platforms have also been used to investigate Lebensspuren on the sea floor (Bett et
al. 1995).
Submersibles
Manned submersibles have been used extensively for the study of deep-sea benthic fauna.
Many of these studies have included some photographic sampling of the benthos along the
submersible track. Grassle et al (1975), in one of the most comprehensive submersible
photographic studies, investigated the pattern of distribution of benthic megafauna along
the well-studied Gay Head-Bermuda transect and provides detailed descriptions of the
ROVs
Remotely Operated Vehicles are becoming increasingly used in deep-sea research and
industry. All are equipped with video systems and often still cameras that can be used in
ecological studies of the seafloor. Real time control of the vehicle allows different survey
strategies to be employed (Barry and Baxter 1992), verification of species and observations
of behaviour (e.g. Hudson and Wigham 2003) to occur. Several polar studies have used
ROVs in a similar way to a towed camera platform to investigate megabenthic diversity
(Starmans et al. 1999; Gutt and Starmans 2003). An increasing number of biological
studies are using ROVs to undertake structured megabenthic survey (Barry and Baxter
1992; Starmans et al. 1999; Gutt and Starmans 2003; Jonsson et al. 2004) and
investigations into polar megabenthos (Hamada et al. 1986; Barthel et al. 1991; Stein et al.
2005).
AUVs
Several Autonomous Underwater Vehicles have been fitted with camera systems although
the technology is not fully developed for imaging, the potential of AUVs for biological
survey is great. AUVs will be able to cover large distances and conduct detailed biological
surveys in the open ocean as well as in habitats that were previously inaccessible such as
Video
Video has been used as an important tool for the study of deep-sea megabenthos (George
et al. 1985; Christiansen 1993; Starmans et al. 1999; Starmans and Gutt 2002; Gutt and
Starmans 2003). It is used more widely in shallow water, particularly in the study of
benthic communities on coral reefs (Leonard and Clark 1993; Carleton and Done 1995;
Aronson and Swanson 1997) as it allows a wide swathe of benthos to be recorded quickly
and by operators with limited identification skills (Ninio et al. 2003). Despite the
continuous coverage of video it has an inherently lower resolution than photographs
(Carleton and Done 1995). It is often combined with photography in the deep sea to
provide a combination of detail and areal coverage (Bett 2001) or to direct the camera to
the most suitable location.
Limitations of photography
Although photography can be a very important tool for the study of megabenthos in the
deep sea it is worth bearing in mind that it has inherent problems. Photographs only show
the epibenthic megafauna, burrowing forms are not seen or at least undersampled.
Estimates of burrowing megafaunal abundance from Lebensspuren (e.g. Ewing and Davis
1967) makes many unfulfilled assumptions and may be misleading (Owen et al. 1967;
Holme and McIntyre 1984). Photographic samples of motile fauna are also likely to be
poor estimates as many will undertake behavioural responses to the camera system and
problem especially in photographs of poor resolution. The solution adopted by many
workers is to take concurrent trawl samples (e.g. Piepenburg and Schmid 1997).
Work in the Polar Regions using deep-sea photography
Photographs of the Antarctic sea floor were first published by Bullivant (1959) showing
massive sponge formations on the Ross Sea floor. At a similar time Hunkins et al. (1960)
published biological observations based on the first photographs of the deep Arctic Ocean
floor. Early deep-water polar photographic megafaunal studies have been reviewed by
Menzies (1962). Since then there have been several megafauna community studies in polar
shelf areas using underwater photography (Simmons and Landrum 1973; Brunchhausen et
al. 1984; Christiansen 1993; Pogrebov et al. 1994; Piepenburg and Schmid 1997; Gutt and
Starmans 1998; Starmans et al. 1999; Sejr et al. 2000; Starmans and Gutt 2002; Barry et al.
2003). Elements of the ecology of several specific groups of polar megafauna have been
investigated using photography, including Antarctic octocorals (Orejas et al. 2002),
Antarctic shrimps (Gutt et al. 1991), Antarctic notothenioid fish (Ekau and Gutt 1991; Gutt
and Ekau 1996; Gutt 2002), Arctic fish (Stein et al. 2005), Antarctic holothurians (Gutt
1988), Antarctic sponge associations (Barthel et al. 1991; Barthel 1992; Barthel and Gutt
1992) as well as the traces (Lebensspuren) that animals create on the seafloor (Hunkins et
al. 1960; Kitchell et al. 1978; Kitchell and Clark 1979). Photography has also been used to
scouring on polar benthos (Gutt et al. 1996; Gutt and Piepenburg 2003; Teixido et al.
2004).