Abundance and diversity of amphipods (Crustacea: Peracarida) on shallow algae and seagrass in lagoonal ecosystem of the Mediterranean Tunisian coast

Zoological Studies

Table 1 Monthly variation of total plant biomass (gDW.m ⁻² ) and amphipod abundance and values of Shannon-Wiener ( H ′) and evenness indexes ( J ′)

	October	November	December	January	February	March	April	May	June	July	August	September	Ni	Di	Ci	Ci × Di	TG
Macroalgae and seagrass
Ulva lactuca	4	7	5.15	2.11	3	3	8	10.73	60	66.10	68.60	30
Cladophora sp.	0	0	7	2	3	3.73	0	0	8	11	0	0
Gracilariopsis longissima	1	4	0	3	14	20	27	30	20.10	11.01	8	9.08
Gracilaria bursa-pastoris	1	4	0	4	15	20	30.18	32	23	11.10	8.01	9
Cymodocea nodosa	38	38.48	30	12	8	7	8	8	16.2	17	17	37.08
Monthly total biomass	44	61.48	41.15	23.11	44	53.73	73.18	80.73	127.12	116.21	96.7	85.16
Amphipods
Gammarus aequicauda (Martynov, 1931)	99	199	87	111	128	132	320	165	172	116	41	233	1,803	49.80	1	49.80	De
Gammarus insensibilis Stock, 1966	89	19	38	113	92	11	89	12	18	13	6	94	594	16.40	1	16.40	De
Gammarella fucicola (Laech, 1814)					15		49	32	18	34	87	81	325	8.97	0.66	5.92	He
Elasmopus rapax Costa, 1853	9	1				5							15	0.41	0.25	0.10	S
Monocorophium acherusicum (Costa, 1853)	7	3					1					4	15	0.41	0.33	0.13	Ds
Ericthonius difformis (Milne-Edwards, 1830)	21	20	28	67	11	48	8	14	8	32	29		286	7.90	0.91	7.18	Ds
Cymadusa filosa Savigny, 1816	13	19	12	6		15	5	14		153	159	84	480	13.26	0.66	8.75	He
Microdeutopus gryllotalpa Costa, 1853							5	10	1	9		9	34	0.94	0.41	0.38	He
Dexamine spinosa (Montagu, 1813)							11	10	4	42			67	1.85	0.33	0.61	De
Caprella sp. (Laech, 1814)		1											1	0.02	0.08	0.00	O
N	238	262	165	297	246	220	488	257	221	399	322	505	3,620	100
H′	2.19	1.53	1.70	1.54	1.37	1.05	1.74	1.74	1.03	1.92	1.68	1.98
J′	0.78	0.54	0.85	0.97	0.68	0.45	0.58	0.62	0.4	0.74	0.72	0.76