Experimental evidence of subsurface feeding by the burrowing ophiuroid Amphipholis gracillima (Echinodermata)

Abstract

Experimental evidence of subsurface feeding by the burrowing ophiuroid Amphipholis gracillima (Echinodermata) 'Marine Science Program, 2~e p a r t m e n t of Biological Sciences, 3Department of Statistics, University of South Carolina, Columbia, South Carolina 29208, USA ABSTRACT: Knowledge of the feeding habits of infaunal deposit-feeders is essential to understand their role in the movement of sediment-bound material and nutrients and in trophic transfer. Depositfeeding ophiuroids are abundant in the world's oceans but many details of their intricate feeding behaviors are unknown. We used fluorescent polystyrene microspheres in a subsurface food layer to demonstrate that Amphipholis gracillima, an infaunal ophiuroid known to feed on surface particles, is also capable of consuming subsurface particles in the laboratory. Although physical conditions varied only slightly during experiments there was a significant effect of temperature on the number of microspheres consumed Additional experiments using layers of m~crospheres with and without food demonstrated that food layers significantly influenced the disc depth of A. gracillima, whereas layers without food did not. Utilizing subsurface sources of food might give burrowing organisms access to more sources of nutrients, decrease sublethal predation and lead to more stable populations over time. 1987, Levinton 1989. Subsurface deposit-feeders, in particular, have the potential to play an important role in the global carbon cycle by increasing the rates of biomineralization and/or decreasing the amount of carbon that is permanently buried. They also have the potential to influence the location and availability of pollutants (Olsen et al. 1982).Infaunal deposit-feeding ophiuroids, although not as thoroughly studied as other groups, are abundant in all oceans of the world and frequently dominate soft bottom macrobenthic communities (Thorson 1957, Barnard & Ziesenhenne 1961, Buchanan 1964, Bowmer & Keegan 1983, Duineveld & Van Noort 1986. Ophiuroids are frequently subjected to lethal or sublethal predation by a variety of fishes, shrimps, and crabs in many parts of the world (Blegvad 1914, Hunt 1925, Duineveld & Van Noort 1986, Feder & Pearson 1988, Theiling 1988, Pape-Lindstrom et al. 1997. They are well known for their ability to rapidly regenerate tissues lost to sublethal predation (Singletary 1970, Bowmer & Keegan 1983, Stancyk et al. 1994, and Pape-Lindstrom et al. (1997) have demonstrated that consumption of infaunal brittlestar arms is a significant trophic pathway in some soft-sediment habitats. Warner (1982,

Quantification of sediment reworking rates in bioturbation research: a review

“…Microspheres are UV fluorescent balls of polystyrene divinylbenzene or latex that have a much smaller size (down to 1 μm) and lower density (e.g. 1.05 g cm -3 for polystyrene microspheres) than luminophores (Gielazyn et al 1999, Ciutat et al 2005). Because of their specific properties, the addition of microspheres does not modify initial sedimentary conditions.…”

Comparative reproductive biology of deep-sea ophiuroids inhabiting polymetallic-nodule fields in the Clarion-Clipperton Fracture Zone

“…This may simply be symptomatic of a patchy (or sex-specific) distribution of females, where large communal echinoderm aggregations in the soft-sediment abyss only really occur during the episodic arrival of labile organic matter to the seafloor (Kuhnz et al, 2014; Smith et al, 2018) or during aggregative spawning events (Mercier and Hamel, 2009). Alternatively, since stomach contents of dissected specimens indicate that O. glabrum is a deposit feeder and deposit-feeding ophiuroids are known to feed infaunally (e.g., Gielazyn et al, 1999), it’s possible that larger females spend more time out of sight below the sediment’s surface foraging for food to meet the nutritional demands of vitellogenesis, which are likely to be considerable, given both the size of mature oocytes and inherent food limitations.…”

The evolutionary relationship between arm vertebrae shape and ecological lifestyle in brittle stars (Echinodermata: Ophiuroidea)

“…Various studies focused on the ophiuroid feeding mechanism (Boos, 2008; Fontaine, 1965; Gielazyn et al, 1999; Harris et al, 2009; Hollertz et al, 1998; Pentreath, 1970), but further research is still required to understand how the vertebral morphology controls the mechanics related to feeding in association with the different lifestyles. In addition, the ecological and functional status of Ophiactis savignyi and Ophiothrix savignyi is not clearly known in the literature.…”