Nutrient uptake controls and limitation dynamics in north-east Greenland streams

Figures & data

Figure 1. Location of the five study streams and associated nutrient uptake experiments.

Table 1. F values from one-way ANOVAs for water temperature between streams during the period 11 July to 15 September. Df = (1, 6358).

	Kærelv	Grænseelv	Aucellaelv	Unnamed
Kærelv		46.1 ^a	743.8 ^a	-
Grænseelv			459.3 ^a	70.6 ^a
Aucellaelv				844.3 ^a
Unnamed

^a p = < 0.0001.

Table 2. Environmental characteristics and background nutrient concentrations of the five study streams. DO measurements are all from 2015. All other conditions measured on day of sampling. Superscript letters indicate significant differences (p < 0.05) between pairs of streams.

Environmental variable		Kærelv	Grænseelv	Unnamed	Aucellaelv	Palnatokeelv
Discharge	L/s	151	189	204	580	247
Channel width	m	3.2	2.6	4	2.8	2.4
Electrical conductivity	µS cm^−1	54	93.1	88.3	192.4	58
Water temperature	°C	7.2^a,b	4^a,b,c	12.1^c	5.8^a,b,c	7
DO	%	76.5	78	88	75.1	77.8
Pfankuch Index		74	78	113	116	114
Suspended sediment	mg L^−1	5.1	7.3	0.5	1120.3	96.3
Dominant bed sediment types	% stone (>6 cm)	31.3	31.6	66.7	79.4	71.6
	% gravel (2–6 cm)	29.8	42.4	20.7	15.5	13.8
Moss coverage	%	2.6	1.9	2	-	-
FBOM	g m^−2	8.11	21.47	19.67	25.94	19.35
	SD	2.04	2.67	8.14	8.28	4.93
Organic matter	%	4.01^c	2.48^c	9.09^c	5.01^c,d	5.84^c,d
	SD	1.34	0.77	2.37	0.76	1.06
Sediment respiration	mg O2 ml^−1 sediment/day	3.43	2.61	1.86^e	1.52^e	4.31^e
	SD	1.09	0.12	0.33	0.17	0.94
Habitat weighted Chl a	µg m^−2	163.49	110.25	218.95	131.92	124.8
	SD	73.63	72.27	91.73	187.88	118.87
TOC	mg L^−1	2.14	2.79	2.93	7.76	1.11
	SD	0.06	0.1	0.3	1.15	0.04
PO4^3+	µg L^−1	3.98^a,b,d,e	1.51^a,b,c,d,e	2.45^b,c,d,e	4.18^a,b,c,d	4.01^a,b,c,e
	SD	0.003	0.004	0.0004	0.002	0.009
NH4^+	µg L^−1	14.53^d	7.47^d	6.7^d	33.81^d	12.48^d
	SD	0.006	0.002	0.002	0.007	0.004
NO3^−	µg L^−1	<0.001^d	0.36^d	0.06^d,e	50.66^d,e	11.79 ^d,e
	SD	0.001	0.001	0.001	0.012	0.008
NH4^+:NO3^−		14,530.00	20.75	111.67	0.67	1.06

Figure 2. Air temperature (line) and precipitation (bars) during the field campaign.

Figure 3. Chl a biomass on stones and gravel in each study stream. Note different Y axis scale. Asterisks highlights significant differences between streams.

Table 3. Nutrient uptake variables during peak snowmelt period in 2014. S_w in m, V_f in m/h, U in µg m⁻² h⁻¹. No detectable uptake is indicated with a dash.

Nutrient addition	Uptake parameter	Stream
		Kærelv	Grænseelv	Unnamed	Aucellaelv	Palnatokeelv
PO4^3-	Sw	586.34	–	686.16	–	163.25
	Vf	0.29	–	0.27	–	2.27
	U	0.46	–	0.04	–	0.55
NH4^+	Sw	192.4	–	–	–	92.79
	Vf	0.88	–	–	–	3.99
	U	0.77	–	–	–	2.99
NH4^+ + Acetate	Sw	–	–	–	–	37.87
	Vf	–	–	–	–	9.78
	U	–	–	–	–	7.33
NO3^−	Sw	–	–	–	–	52.43
	Vf	–	–	–	–	7.07
	U	–	–	–	–	4.22

Table 4. Two-way ANOVA results for NDS investigations to determine limiting or used nutrients in each stream. For all sites and substrate types n = 20. F values presented. Significant p values are in boldface.

Stream	Substrate	NH4^+	PO4^3-	NH4^+ * PO4^3-
Kærelv	Glass	58.65 ^b	3.86	7.59 ^a
	Sponge	22.1 ^b	4.98 ^a	0.46
Grænseelv	Glass	95.1 ^b	<0.00	2.07
	Sponge	3.54	0.1	6.19 ^a
Unnamed	Glass	23.5 ^b	9.4 ^b	8.48 ^a
	Sponge	5.75 ^a	0.06	8.52 ^a

^a p = < 0.05. ^b p = < 0.001.

Figure 4. Chl a content in biofilm following different nutrient additions after 16 days.