Classifying aquatic macrophytes as indicators of eutrophication in European lakes

Abstract

Aquatic macrophytes are one of the biological quality elements in the Water Framework Directive (WFD) for which status assessments must be defined. We tested two methods to classify macrophyte species and their response to eutrophication pressure: one based on percentiles of occurrence along a phosphorous gradient and another based on trophic ranking of species using Canonical Correspondence Analyses in the ranking procedure. The methods were tested at Europe-wide, regional and national scale as well as by alkalinity category, using 1,147 lakes from 12 European states. The grouping of species as sensitive, tolerant or indifferent to eutrophication was evaluated for some taxa, such as the sensitive Chara spp. and the large isoetids, by analysing the (non-linear) response curve along a phosphorous gradient. These thresholds revealed in these response curves can be used to set boundaries among different ecological status classes. In total 48 taxa out of 114 taxa were classified identically regardless of dataset or classification method. These taxa can be considered the most consistent and reliable indicators of sensitivity or tolerance to eutrophication at European scale. Although the general response of well known indicator species seems to hold, there are many species that were evaluated differently according to the database selection and classification methods. This hampers a Europe-wide comparison of classified species lists as used for the status assessment within the WFD implementation process.

Appendix

List of species per species group included in REBECCA macrophyte study, with results of classifications. Column headings ‘P’ and ‘L’ represent methods based on percentiles or on LEAFPACS, respectively, and ‘n’ is the number of lakes in which a species occurred

	Species	All		N-GIG		C-GIG		CH			CL			NH			NL			Norway		Finland		Latvia
		P	n	P	n	P	n	P	L	n	P	L	n	P	L	n	P	L	n	P	n	P	n	P	n
I	Baldellia ranunculoides	o	8	+	5		1						1	+	+	4			1
I	Crassula aquatica	o	24	o	24												o	+	24	−	8	o	8
I	Elatine hexandra	−	20	o	8	−	5			1	+	+	4				o	+	8		3
I	Elatine hydropiper	−	131	−	128		1			1							−	+	124	o	13	−	74
I	Elatine orthosperma		3		3														3		3
I	Elatine triandra	o	57	o	57												+	+	56	+	5	o	41
I	Eleocharis acicularis	−	394	−	372	−	18	−	−	11	−	−	7	+	+	31	−	−	328	−	56	−	189	−	9
I	Eriocaulon aquaticum	−	20		1														1
I	Isoetes echinospora	−	380	−	378											2	−	−	365	−	101	−	186
I	Isoetes lacustris	−	487	−	424	−	13			2	−	−	11			3	−	−	405	−	117	−	197	−	7
I	Limosella aquatica	−	23	o	23											1	−	−	22	−	11	o	4
I	Littorella uniflora	−	207	−	130	−	16	−	− −	7	−	−	9	+	+	12	−	−	118	−	55	−	16
I	Lobelia dortmanna	−	292	−	260	−	4				−	−	4	+	−	6	−	−	251	−	81	−	102
I	Lythrum portula	o	13	−	12		1						1			1	o	+	11	o	7
I	Ranunculus reptans	−	462	−	462									+	−	21	−	−	419	−	88	−	256
I	Subularia aquatica	−	323	−	319		3						3			2	−	−	302	−	75	−	157
E	Callitriche cophocarpa	o	25	+	25											3	+	+	21	+	9	+	14
E	Callitriche hamulata	−	93	−	78	o	5			1	−	−	4			2	−	−	76	−	63		1
E	Callitriche hermaphroditica	o	101	−	79	o	13	o	−	8	+	+	5	+	−	19	−	+	58	−	27	−	24
E	Callitriche palustris	o	224	−	223		1			1				o	−	4	−	−	210	−	46	o	112
E	Callitriche stagnalis	o	15	o	8	o	5			3			2				o	+	8	o	6
E	Ceratophyllum demersum	+	184	+	90	+	87	+	+	83	+	+	4	+	+	33	+	+	53	+	17	o	30	+	61
E	Elodea canadensis	o	237	o	107	o	78	o	−	60	+	+	18	+	+	30	−	+	75	o	23	o	39	o	49
E	Elodea nuttallii	+	20		2	+	15	+	+	14			1						2
E	Hydrilla verticillata		2				2			2															2
E	Myriophyllum alterniflorum	−	482	−	419	−	24	−	− −	11	−	−	13	o	− −	22	−	−	387	−	115	−	185	−	12
E	Myriophyllum sibiricum	−	45	−	45									−	−	6	−	+	37	−	15	−	30
E	Myriophyllum spicatum	+	184	+	68	o	90	o	+	79	o	+	11	+	+	44	+	+	24	+	9			o	56
E	Myriophyllum verticillatum	+	79	+	53	+	26	+	+	24			2	+	+	13	+	+	38	+	5	+	28	+	16
E	Najas flexilis	o	11	+	7											3	+	+	4		2		1
E	Najas marina	+	24			+	24	+	−	24
E	Najas tenuissima	−	3		3														3				3
E	Potamogeton acutifolius		2				2			2
E	Potamogeton alpinus	−	311	−	296	−	8			3	−	−	5	−	− −	29	−	+	255	o	90	o	144
E	Potamogeton berchtoldii	−	322	o	284	−	8			2	o	+	6	+	−	27	−	+	245	o	83	−	138
E	Potamogeton compressus	o	83	o	65	+	18	o	+	18				+	+	12	o	+	51		2	−	30	o	6
E	Potamogeton crispus	+	94	+	52	o	31	+	+	28			3	+	+	24	o	+	28	+	7		4	+	5
E	Potamogeton filiformis	−	82	−	63	−	11	−	− −	9			2	−	−	30	−	−	33	−	38	−	11
E	Potamogeton friesii	o	61	o	45	o	14	o	−	14				+	+	36	−	+	9	+	21				2
E	Potamogeton gramineus	−	317	−	285	−	20	o	−	11	−	−	9	o	−	33	−	+	245	−	66	−	128	+	8
E	Potamogeton lucens	o	181	+	64	o	93	o	−	84	+	+	9	+	+	37	−	+	26	+	11	−	5	o	74
E	Potamogeton obtusifolius	o	177	+	151	+	11	+	+	7	+	+	4	+	+	28	+	+	120	+	30	+	55		1
E	Potamogeton pectinatus	+	128	+	45	+	71	+	+	68			3	+	+	30	o	+	15	+	10		1	o	9
E	Potamogeton perfoliatus	o	627	−	470	o	115	o	−	99	o	+	16	o	−	56	−	+	394	o	73	−	239	−	75
E	Potamogeton polygonifolius	−	23	−	18		1			1							−	− −	18	−	16
E	Potamogeton praelongus	−	224	−	199	−	22	−	−	16	o	+	6	o	−	43	−	+	153	−	47	−	62	−	18
E	Potamogeton pusillus	+	56	o	19	+	30	+	+	29			1	+	+	7	−	+	12	+	4	+	6
E	Potamogeton rutilus	o	23	o	17	o	5			3			2	+	+	5	o	+	12	+	9	+	4		1
E	Potamogeton trichoides	+	10			+	10	+	+	10
E	Potamogeton vaginatus		2		2											1			1		1		1
E	Potamogeton gramineus × perfoliatus	o	39	o	31	o	6	o	−	4			2	+	−	14	−	+	17	−	12				1
E	Potamogeton gramineus × natans	−	4	−	4												−	−	4		3
E	Potamogeton filiformis × pectinatus		3		3											2			1		3
E	Potamogeton gramineus × lucens	−	25	−	24									−	−	10	−	+	14		3
E	Ranunculus aquatilis	o	58	o	25	−	31	−	−	29			2	+	+	10	−	+	15	o	12			−	24
E	Ranunculus baudoti		3				2			2
E	Ranunculus circinatus	+	36	+	25	+	10	+	+	9			1	+	+	20	+	+	5
E	Ranunculus confervoides	−	43	−	43									−	− −	9	−	−	34	−	32	−	4
E	Ranunculus peltatus	−	249	−	249									+	−	18	−	−	222	−	29	−	133
E	Ranunculus penicillatus		1
E	Utricularia australis	−	7	−	7												−	+	7			−	7
E	Utricularia intermedia	−	130	−	127									−	−	7	−	−	114	−	38	o	57
E	Utricularia minor	−	85	−	83		1						1	−	−	4	−	−	77	−	50	o	24		1
E	Utricularia ochroleuca	−	30	−	30												−	− −	30	−	27		3
E	Utricularia vulgaris	o	418	−	364	o	38	o	−	34	o	+	4	−	+	41	−	+	308	−	53	o	173	−	25
E	Zannichellia palustris	+	36	+	15	+	20	+	+	17			3	+	+	8	+	+	7		2
N	Nuphar lutea	o	766	o	572	o	154	o	−	122	+	+	32	+	+	73	−	+	473	o	111	o	248	+	118
N	Nuphar pumila	o	206	−	178	o	25	o	−	14	+	+	11			3	−	+	165	−	19	o	117	+	24
N	Nuphar lutea × pumila	−	174	−	172		2			1			1				−	−	154			−	134
N	Nymphaea alba	o	454	o	416	o	26	o	+	22	o	+	4	−	−	56	−	+	350	o	109	o	163	−	11
N	Nymphaea candida × tetragona		2		2														2				2
N	Nymphaea candida	o	86	o	30	o	56	o	+	46	+	+	10			3	−	+	27					−	50
N	Nymphaea tetragona	o	24	o	24												o	+	23			o	24
N	Nymphaea alba × candida		3				3			3
N	Nymphoides peltata	+	4			+	4	+	+	4
N	Persicaria amphibia	o	208	o	184	−	13	−	−	8	+	+	5	+	+	43	o	+	140	o	35	o	63
N	Potamogeton natans	o	669	o	513	−	129	o	−	102	+	+	27	−	−	83	o	+	422	o	133	o	189	o	107
N	Sagittaria natans	o	68	o	68												o	+	66			o	53
N	Sagittaria sagittifolia × natans	+	8	+	8												+	+	7			+	8
N	Sparganium angustifolium	−	396	−	388		2						2	−	− −	15	−	−	348	−	147	−	196
N	Sparganium gramineum	o	205	o	205											2	o	+	201		1	o	138
N	Sparganium hyperboreum	−	27	−	27											1	−	− −	26	−	20	−	6
N	Sparganium natans	o	99	o	97									−	−	5	o	+	88	−	12	o	54
N	Sparganium angustifolium × gramineum	−	21	−	21												−	+	21				2
L	Hydrocharis morsus-ranae	+	120	+	76	+	44	+	+	37	+	+	7	+	+	25	+	+	48			+	30	+	25
L	Lemna gibba	+	7		2	o	5	o	+	5						1			1						1
L	Lemna minor	+	264	+	215	+	47	+	+	42	+	+	5	+	+	53	+	+	158	+	56	+	81	+	18
L	Lemna trisulca	+	146	+	78	+	36	+	+	33			3	+	+	26	+	+	51	+	4	+	23	o	14
L	Salvinia natans	+	7			+	7	+	+	7
L	Spirodela polyrhiza	+	84	+	58	+	26	+	+	24			2	+	+	22	+	+	34	+	13	+	19	+	9
L	Stratiotes aloides	+	60	+	56	+	4	+	+	4				+	+	26	o	+	28			o	13
L	Trapa natans	+	5			+	5	+	+	4			1												2
C	Chara aspera	o	76	o	49	−	23	−	− −	21			2	o	−	28	−	+	20	o	12	−	11		3
C	Chara connivens	+	15			−	15	−	− −	15
C	Chara contraria	o	47	o	22	−	25	−	− −	24			1	o	−	16	o	+	6	−	5			−	5
C	Chara delicatula	−	15	−	12		3			3				−	−	9			3	−	10
C	Chara filiformis		2		1		1			1						1
C	Chara fragilis	o	10	o	10											1	o	+	9			o	6
C	Chara globularis	o	135	−	97	−	33	−	−	26	−	+	7	o	−	30	−	+	63	−	40	−	25
C	Chara hispida	o	22	o	7	−	14	−	− −	14				o	−	4			3					−	4
C	Chara intermedia		2		1		1			1						1					1				1
C	Chara rudis	o	20	−	15	−	5	−	− −	5				−	−	14			1	−	11				2
C	Chara strigosa	−	7	−	6		1			1						3			3	−	6
C	Chara tomentosa	o	24	+	10	o	14	o	− −	14				−	−	9			1	+	4			o	9
C	Chara vulgaris	o	12			−	10	−	−	10															2
C	Nitella confervacea		2		2														2		1		1
C	Nitella flexilis	o	48	−	29	o	10	+	−	6	−	+	4				−	+	27			−	25
C	Nitella mucronata	o	8		2	+	6	o	+	6									2		2
C	Nitella opaca	−	142	−	132	o	6			3			3	o	−	6	−	−	121	−	67	−	51
C	Nitella translucens		3		2		1						1						2
C	Nitella wahlbergiana		3		3														3				2
C	Nitellopsis obtuse	+	41		1	+	40	+	+	40						1								o	10
C	Tolypella canadensis	−	5	−	5												−	− −	5	−	5
C	Tolypella glomerata		3				2			2

1. Classifications in the percentiles method are Sensitive (−), Tolerant (+) and Indifferent (o). LEAFPACS classifications are positive responder (+), negative responder (−), or strongly negative responder (− −).C = Central GIG, N = Northern GIG, H = High alkalinity, L = Low-moderate alkalinity. Species groups: I—isoetids, E—elodeids, N—nymphaeids, L—lemnids, C—charids