SESSION SUMMARY: DEEP WATER ECOLOGY 



Larry Madin 



Woods Hole Oceanographic Institution 



Woods Hole, MA 02543 



The five papers presented in this chapter include two 

 research projects of an experimental nature in the benthic 

 environment, and three reports on work of a more observational 

 nature in midwater. 



Mullineaux's study of larval settlement patterns within 

 known flow regimes is a pioneering extension of laboratory and 

 shallow water research into the deep sea. In the last decade, 

 studies of settlement behavior have moved out of benchtop beakers 

 into experimental flumes, shallow water environments and now the 

 open ocean. Along the way, a new understanding of the flow 

 regime above the bottom and around hard substrates has radically 

 altered our concept of the forces that determine larval settling 

 patterns, and consequently the spatial distribution and 

 composition of benthic communities. The crucial combination in 

 these studies is simultaneous observation of the flow regime 

 around the substrate, and the actual pattern of larval settling. 

 Mullineaux has used a sophisticated current meter to record the 

 larger scale properties of the bottom currents, and alabaster 

 dissolution plates to register the fine scale flow which actually 

 impinges on the settlement substrates. 



A study of this nature requires precise placement of the 

 settling plates and other instruments on an appropriate bottom, 

 and recovery of the equipment without damaging the plates or 

 dislodging the settled larvae. Clearly, a manned submersible is 

 the only way this could have been accomplished at these depths. 

 The success of this effort illustrates how well experimental 

 techniques developed in shallow water for SCUBA divers can be 

 transplanted to the deep sea, using modern submersibles and 

 auxiliary equipment. 



The second benthic study, by Grassle, Snelgrove, Weinberg 

 and Whitlatch, also demonstrates use of the submersible to carry 

 out experimental manipulations on the deep sea floor. As 

 Mullineaux's work is concerned with colonization of hard 

 substrates, Grassle is interested in colonization of the 

 sediments, and factors affecting the abundance and diversity of 

 the infauna. 



Spatial and temporal variability of the food supply to the 

 deep benthos is one of these factors. Against a background 

 "rain" of fine particulate matter from the water column, there 

 are episodic arrivals at the bottom of larger chunks of food, 



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