Table 1. Summary of activities of the three enzymes.

					Total (Untreated)			Dissolved (Filtration)
Site	Enzyme	Species	No. of sampled pitchers	No. of pitchers that had positive enzyme activity	Mean enzyme activity (mmol l−1 h−1)	±	SD	Mean enzyme activity (mmol l−1 h−1)	±	SD	Mean ratio of dissolved enzyme activity to total	±	SD
Borneo	Acid phosphatase	N. albomarginata	6	6	23.09	±	4.61	22.60	±	5.17	0.97	±	0.04
	(AP)	N. ampullaria	14	14	6.52	±	5.82	4.16	±	4.10	0.82	±	0.46
		N. bicalcarata	8	8	9.28	±	7.17	7.32	±	7.89	0.59	±	0.38
		N. gracilis	15	15	28.88	±	24.47	19.24	±	11.10	0.76	±	0.22
	beta-D-glucosidases	N. albomarginata	6	3	9.60	±	7.14	5.68	±	7.18	0.57	±	0.36
	(BG)	N. ampullaria	19	15	0.59	±	0.55	0.42	±	0.46	0.64	±	0.65
		N. bicalcarata	8	7	2.61	±	2.41	1.17	±	1.51	0.40	±	0.36
		N. gracilis	15	9	2.27	±	2.28	1.11	±	0.85	0.70	±	0.47
	beta-D-glucosaminidases	N. albomarginata	6	2	1.21	±	1.69	1.20	±	1.68	1.00	±	0.01
	(NAG)	N. ampullaria	19	10	0.70	±	1.16	0.55	±	0.99	0.56	±	0.45
		N. bicalcarata	8	7	2.64	±	2.81	1.47	±	1.95	0.41	±	0.32
		N. gracilis	15	7	1.07	±	1.18	0.17	±	0.18	0.18	±	0.25
Zurich	Acid phosphatase	N. ampullaria	6	6	0.16	±	0.02	0.16	±	0.01	0.99	±	0.06
	(AP)	N. bicalcarata	5	5	0.33	±	0.09	0.23	±	0.05	0.70	±	0.13
		N. gracilis	4	4	6.48	±	7.89	1.85	±	1.75	0.49	±	0.29
	beta-D-glucosidases	N. ampullaria	6	6	0.03	±	0.01	0.01	±	0.01	0.75	±	0.70
	(BG)	N. bicalcarata	5	5	0.05	±	0.03	0.04	±	0.05	0.72	±	0.43
		N. gracilis	4	4	0.14	±	0.13	0.08	±	0.06	0.61	±	0.13
	beta-D-glucosaminidases	N. ampullaria	6	5	0.02	±	0.00	0.01	±	0.00	0.60	±	0.22
	(NAG)	N. bicalcarata	5	5	0.05	±	0.03	0.04	±	0.05	0.58	±	0.46
		N. gracilis	4	4	0.38	±	0.40	0.07	±	0.06	0.32	±	0.17