Attached and Free-Floating Bacteria in a Diverse Selection of Water Bodies COLIN R
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APPLIED AND ENVIRONMENTAL MICROBIOLOGY, June 1982, p. 1227-1237 Vol. 43, No. 6 0099-2240/82/061227-11$02.00/0 Attached and Free-Floating Bacteria in a Diverse Selection of Water Bodies COLIN R. BELL AND LAWRENCE J. ALBRIGHT* Department ofBiological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada VSA IS6 Received 21 September 1981/Accepted 3 February 1982 The contribution of attached and free-floating bacteria to the bacterial numbers and heterotrophic uptake in 44 diverse aquatic environments was studied. A factor analysis reduced the variability of the raw data base to three major factors explaining 53.6% of total variance. These factors were (i) salinity, (ii) heterotro- phic uptake, and (iii) particulate load. A cluster analysis categorized the 44 habitats into five distinct environmental types based on these three factors. There was no significant pattern in the distribution of attached versus free-floating bacteria when assessed by epifluorescent microscopy. However the contribution of attached bacteria to the uptake of an amino acids mix was reduced in marine waters. Heavy particulate loads resulted in an increased percentage uptake of amino acids and glucose from the attached bacteria. Uptake response was found to be substrate specific especially in oliogotrophic freshwater. Amino acid uptake was more associated with the attached fraction, whereas glucose uptake was mediated more by the free-floating fraction. The association of bacteria with particulate from the depths listed in Table 1 with a 7-liter Van material is of considerable importance in aquatic Dorn bottle. All samples were processed immediately environments. Bacteria are one of the major after collection. agents responsible for the alteration of particu- Physicochemical determinations. Temperature was measured with a simple mercury thermometer. pH and late matter through processes such as decay and salinity and conductivity were determined with a Fish- flocculation (16-18). They are able to convert er model 107 portable pH meter and a Yellow Springs dissolved organic matter to particulate organic Instruments model S-C-T 33 salinometer, respective- matter (2), and their ultimate fate in the water ly. The total volume and modal size of particulates will be greatly influenced by the material to were counted later in the laboratory with a Coulter which they are attached (20). Counter TA II with 280- and 100-rm-diameter aper- Most authorities agree that in the open ocean tures. This covered particles in the diameter size range planktonic bacteria are unattached and free of 1.26 to 80.64 ,um. Seston was determined as an In freshwater environments estimate of the organic particulates in the waters. A floating (6, 22, 24). known volume ofwater was filtered through a predried the degree of attachment varies considerably (4, and tared Whatman GFF filter which was fixed by 5, 7, 8, 14, 19). However evidence is accumulat- placing in a petri plate with a pad soaked in Formalin. ing in studies on rivers that as the freshwater The filter was later ashed in a furnace at 500°C for 24 h. flows into the sea the degree of attachment The weight of material burned off was reported as decreases with increasing salinity (9, 25). seston. Particulate organic carbon (POC) was defined We observed a similar decrease in numbers as the organic carbon retained on a GFF filter previ- and activities of attached bacteria in the Fraser ously baked for 24 h at 500°C. The filtrate was consid- River Estuary as it entered the Strait of Georgia ered to be dissolved organic carbon (DOC). Both POC To assess how universal the and DOC samples were fixed in the field by freezing in (3). relationship dry ice and were kept frozen until ready for analysis. between attachment and salinity was and also to POC was determined with a Perkin Elmer Elemental explore other influences, we embarked on a Analyser 240. DOC was analyzed on a Beckman study of 44 aquatic environments, 15 of which Tocamaster model 915-B. were coastal marine. The results of this study Information on the location and elevation of each are reported herein. sample site was taken from topographical maps. Two location parameters, called X coordinate and Ycoordi- MATERIALS AND METHODS nate, were entered into the statistical analyses to Collection of water samples. A total of 44 water detect any influences attributable to the proximity of samples were collected over the period 26 May 1980 to the urban and industrial centre of Vancouver. The X 25 November 1980. The majority of these samples (40) coordinate measures minutes of longitude west of were taken from the surface water in sterile Nalgene sample no. 32, Lost Lagoon. The Y coordinate mea- containers. The remaining four samples were collected sures minutes of latitude north of sample no. 32. Lost 1227 1228 BELL AND ALBRIGHT APPL. ENVIRON. MICROBIOL. TABLE 1. Site number and location Site no. Location Longitude Latitude 1 Porlier Pass 123035'W 49001'N 2 Active Pass 123019'W 48052'N 3 Nanaimo River Estuary 123054'W 48008'N 4 Howe Sound (250 m) 123015'W 49005'N 7 Howe Sound (8 m) 123015'W 49005'N 8 Indian River Estuary 122053'W 49029'N 10 Indian Arm (200 m) 122052'W 49023'N 11 S.F.U. Reflecting Pool 122055'W 49017'N 12 Fraser River 122055'W 49012'N 13 Burnaby Lake 122057'W 49015'N 14 Buntzen Lake 122052'W 49020'N 15 Chadsey Lake 122009'W 490 TN 16 Marion Lake 123010'W 49033'N 17 Cheakamus Lake 122056'W 50001'N 18 Lindeman Lake 121°27'W 49007'N 19 Levette Lake 123011'W 49050'N 20 Pacific Ocean 125040'W 49043'N 21 Pacific Ocean (150 m) 125040'W 49043'N 22 Alberni Inlet 124048'W 49009'N 23 Trevor Channel 125009'W 48051'N 24 Goldie Lake 122056'W 49022'N 25 Henriette Lake 123020'W 49041 'N 26 First Lake 123°11'W 49023'N 27 Wedgemount Lake 122049'W 50010'N 28 Lafarge Lake 122046'W 49017'N 29 Killarney Lake 123021 'W 49024'N 30 Greendrop Lake 121026'W 49009'N 31 Mill Lake 122019'W 49003'N 32 Lost Lagoon 123008'W 49018'N 33 Garibaldi Lake 123001'W 49055'N 34 Hicks Lake 121°42'W 49020'N 35 Pitt Lake 122035'W 49021 'N 36 Serpentine River 122045'W 49008'N 37 Squamish River 123016'W 49053'N 38 Chilliwack River 121058'W 49006'N 39 Bute Inlet 124050'W 50053'N 41 Homathko River 124052'W 50057'N 42 Calm Channel 125006'W 50021 'N 43 Robert Burnaby Park Creek 122056'W 49014'N 44 Post Creek 121°29'W 49006'N 45 Steveston Drainage Ditch 123005'W 49008'N 46 Fraser River Estuary 123008'W 49°06'N 47 Georgia Strait 123030'W 49009'N 50 Sewage Effluent (Annacis Island) 122058'W 49°10'N Lagoon was chosen as a convenient reference point as and 97% of all particulates in the estuary were retained it is situated in downtown Vancouver. by this filter, yet in samples which had a predominance Biomass determinations. Chlorophyll a was deter- of free-floating bacteria, 98% of the bacteria passed mined spectrophotometrically after acetone extraction through the filter. Samples were fixed in the field with with Millipore 0.8-,um pore size filters (23). The filters 2% (vol/vol) Formalin. were removed from the field wrapped in foil and Heterotrophic uptake. The turnover time of glucose analyzed within a few days. Bacterial numbers were and an amino acid mix was calculated by the method estimated by the acridine orange direct count (AODC) of Azam and Holm-Hansen (1). D-[6-3H]glucose (spe- method of Hobbie et al. (10). Bacteria attached to cific activity, 30 Ci/mmol; New England Nuclear particles, which included bacterial aggregates and bac- Corp.) and a mixture of 15 tritiated L-amino acids teria attached to plankton, were distinguished from (New England Nuclear Corp.; code no. NET-250) free-floating bacteria after removal of the bulk of the were diluted to a working concentration of 10 ,uCi/ml. particles by gently filtering 10 ml of water sample The relative uptake of each amino acid within the through Nuclepore 1.0-,m pore size filters. This pro- mixture could not easily be determined, so calcula- cedure has been tested extensively in the varying tions to specific concentrations of amino acids and conditions of the Fraser River Estuary (3). Between 60 glucose were not attempted. The water sample was VOL. 43, 1982 BACTERIA IN A SELECTION OF WATER BODIES 1229 SITE No. 01 39 02 go 23 CLUSTER A 03 33 08 20 hUIllQ 07 47 21 .XX1K 9, CLUST~ER B 42 46 10 +X+xs ".. 05 14 38 -+-. .+. 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