Evaluation of a Pump and Reeled Hose System for 

 Studying the Vertical Distribution of Small Plankton 



By 



RODERICK LEONG, Fishery Biologist 



Bureau of Commercial Fisheries 



California Current Resources Laboratory, 



La Jolla, Calif. 92038 



ABSTRACT 



The system consists of a submerged pump that delivers water from sampling 

 depth to inboardfiltersthroughalonghose.lt features a special winch that can store 

 more than 120 m. of collapsible, large-diameter hose. Sources of error due to frag- 

 mentation and dispersion of organisms during passage through the system, arid 

 escapement through the strainers, were examined. Fragmentation maybe excessive 

 if animals are fragile or longer than 5 mm. Organisms that enter the system simul- 

 taneously may become widely dispersed but most remain together. Strainers of 100// 

 mesh (bar measure) retain organisms as narrow as 100//. 



The capabilities of the pump were illustrated by its use in obtaining vertical 

 profiles of abundance of eggs and larvae of sardines ( Sardinops caerulea) and of 

 chaetognaths and doliolids at one station. The eggs and larvae were clearly restricted 

 to the upper mixed layer and upper part of the thermocline. Numbers of chaetognaths 

 increased and numbers of doliolids decreased with increasing depth. The advantages 

 and limitations of the pump for studying vertical distribution are discussed. 



INTRODUCTION 



O'Connell and Leong (1963) described a 

 towed plankton pump system that could collect 

 horizontal samples of small plankton at speeds 

 up to 9 knots and at depths to 5 m. The pur- 

 poses of this report are to evaluate the system 

 as a vertical sampler and to describe modifi- 

 cations which increase its vertical range to 

 more than 100 m. General design, field per- 

 formance, and sources of sampling error are 

 discussed. The capabilities of the system are 

 evaluated by its effectiveness in obtaining 

 vertical profiles of sardine eggs and larvae, 

 chaetognaths, and doliolids at one station. 



GENERAL DESIGN AND PERFORMANCE 



The system consists of a submerged pump 

 that forces water through a long hose to one 

 of two strainers in the laboratory (fig. 1). 

 A submersible electric pump (1.27-cm. intake, 

 0.5 hp., 3,450 r.p.m.) at the bottom of the 

 system draws in water and forces it through 

 a short connector hose and then through a 

 firehose 120 m. long and 5 cm. in diameter. 

 A stainless steel support cable (0.64-cm. 

 diameter) and an electric cable (1.27-cm. 

 diameter) that powers the pump run through 



the length of the hose. The hose is supported 

 by a large net roller (20-cm. diameter and 

 1 m. long) on the stern and is connected to a 

 special winch on the deck. Water is piped 

 from the winch to the ship's laboratory, where 

 it passes through a watermeter andis directed 

 to one of two strainers by a switch valve. 

 One strainer is used while the other is being 

 serviced. O'Connell and Leong (1963) give 

 further details of construction and operation. 

 The winch had to be extensively modified to 

 store the great length of large-diameter hose 

 needed for deep vertical sampling. The present 

 winch (fig. 2a) is capable of storing three 

 layers of collapsible hose without compressing 

 the inner layers. It has a three-level reel 

 which consists of a central rotating drum 

 (1-m. diameter and 1.5 m. long) and two 

 concentric outer shells with interspaces of 

 10 cm. These shells bear the weight of the 

 hose and keep the layers separated. A slot on 

 the edge of the shell (fig. 2c) allows the hose 

 to pass from one level to the next. To permit 

 spooling on all levels, the shells are built 

 in detachable quarter sections that weigh about 

 20 kg. each. Each section is supported by a 

 series of alternating rods and plates which 

 project from the level beneath (fig. 2b). Each 

 section is bolted to the plates that support it. 



