Large versus small zooplankton in relation to temperature in the Arctic shelf region

Figures & data

Figure 1. The Hornsund region study area. Sections of an LOPC-CTD-F platform towed across the West Spitsbergen Shelf over seven summer seasons (July-August 2010–2016) are indicated by measuring points assigned to three zones. The shelf break (200 m isobath) is marked by a solid blue line. The bird icon indicates the location of the little auk colony in Hornsund.

Figure 2. Mean depths of concentration of (a) small zooplankton, (b) large zooplankton and (c) chlorophyll fluorescence in the upper 50 m water layer over five summer seasons (2012–16) in three different zones of the West Spitsbergen Shelf area.

Figure 3. Distribution of the (a) seawater temperature, (b) chlorophyll fluorescence and (c) small zooplankton (ind. m⁻³) over seven summer seasons (2010–16) at 20–30-m depth layer along transect on the West Spitsbergen Shelf. Note the scale difference.

Table 1. Average abundance (ind. m⁻³) of the small size fraction over seven summer seasons (2010–16) in three zones (Arctic, Frontal and Atlantic) of the WSS at 20–30-m depth.

Zone	Arctic			Frontal			Atlantic
Year	mean	SD	n	mean	SD	n	mean	SD	n
2010	10,680	5736	9137	13,706	5131	5888	17,486	8148	21,114
2011	6196	5392	3063	13,757	9854	2174	50,886	53,835	3927
2012	2597	1611	380	4827	3566	167	34,137	23,257	436
2013	236,486	116,881	1691	85,951	77,781	3344	31,734	42,461	4026
2014	5361	5109	3539	6424	3379	1255	2899	2609	3075
2015	12,778	8157	3697	11,254	4861	937	11,589	3526	1262
2016	7439	4061	1115	37,897	15,208	160	no data

Table 2. Average abundance (ind. m⁻³) of the small size fraction (small) and the Calanus size fraction (large) over five summer seasons (2012–16) in three zones (Arctic, Frontal and Atlantic) of the WSS in the upper 50 m layer.

		Arctic Zone			Frontal Zone			Atlantic Zone
Year	Fraction	mean	SD	n	mean	SD	n	mean	SD	n
2012	Small	2609	1772	1500	6041	6337	718	23,878	22,968	1904
	Large	695	1369		1004	2250		1025	3051
2013	Small	211,347	115,040	7392	98,542	95,687	14,405	30,967	47,683	18,057
	Large	5615	4195		1494	3369		862	2269
2014	Small	4925	5254	9717	4738	3456	4469	2736	2367	11,104
	Large	84	233		99	261		206	449
2015	Small	12,323	10,090	4965	9905	4724	1880	11,483	3734	1825
	Large	1940	4227		4758	5414		3062	4659
2016	Small	7704	5157	4357	27,574	14,561	748	no data
	Large	1481	2432		1061	3660

Figure 4. Vertical profiles of the mean and 95% CI of the (a) water temperature, (b) chlorophyll fluorescence and (c) percentage of large zooplankton in total plankton abundance the upper 50 m water layer over five summer seasons (2012–16) in three different zones (Arctic Zone marked in blue, Frontal Zone marked in green and Atlantic Zone marked in orange).