Aquatic macrophytes

• Aquatic macrophytes are macroscopic forms of aquatic vegetation; they include macroscopic algae (such as Nitella and Chara), some fern and mosses (pteridophytes) and many flowering plants (angiosperms)

• Aquatic macrophytes can be grouped into two main groups:

1. ACQUATIC MACROPHYTES ROOTING IN SEDIMENT

2. FREELY FLOATING MACROPHYTES

ACQUATIC MACROPHYTES ROOTING IN SEDIMENT

• Emergent aquatic macrophytes are rooted in the sediment and may grow in a water depth of 1 m ( i.e.Typha spp,Scirpus lacustris, Sagittaria sagittifolia). During the growing season all members of this group produce aereal leaves and flowers

• Floating-leaved aquatic macrophytes may root in a depth up to 3 m and have floating or aereal flowers. Nymphaeae spp., Potamogeton natans and Nuphar lutea belong to this group.

• Submersed macrophytes complete their life cycle under the water surface and include flowering plants as Potamogeton pectinatus, P.perfoliatus and Myriophillum spicatum, some moss species like Fontanilis antipyretica and algae as Chara and Nitella

FREELY FLOATING MACROPHYTES

These macrophytes live unattached in the water. The life forms range from macrophytes with floating or aerial leaves and well developed submersed roots to very small surface floating or submersed plants with few or no roots ( i.e. Lemna trisulca). Some plants in this group have aerial flowers ( Utricularia vulgaris), others complete their life cycle under the water surface ( Ceratophyllum demersum).

Ecology

There are some environmental factors thatcan influence the development of macrophytes ABIOTIC FACTORS BIOTIC FACTORS ANTHROPIC FACTORS

ABIOTIC FACTORS• Sunlight:The photosynthetic rate of plants

depends on the quantity of the sunlight.• Temperature: It determines not only the

phenology of the plants but also the coenosis• River dynamics: the flow rate is the more

important factor for the development of a population of macrophytes.

• The depth. It determines the quantity of light and, consequently, the photosynthetic rate

• The transparency. It is conditioned by the flow and influences the penetration of the sunlight.

• Substratum. The stability of the bottom is one of the factors conditioning the development of macrophytes

• Chemical features The levels of nitrates and phosphates are particularly important for the growth of macrophytes but also alcalinity can influence the plant coenosis.

• Sediment. It is the primary source of nitrogen and phosphorous for the deep-rooted macrophytes.

• Altitude.It determines the flow, the water speed, the water quality, the depth and, so, it can influence the growth of macrophytes.

BIOTIC FACTORS• Reproduction: the macrophytes can have

aerial or submersed reproductive organs• Dispersion modality: the most common

diffusion system is by piping• Interspecific relations. There are

competition and cooperation between different species

• Interaction with the animal component: there are animals that eat macrophytes.

ANTHROPIC FACTORS• Works along the river banks can alter

the macrophyte coenosis

• Alteration of the chemical composition for

1. Eutrophication

2. Presence of pesticides

3. Other polluting substances

• Mow the grass along the banks

Aquatic macrophytes can be considered good biological indicators of

pollution because • they are sensitive to pesticides, to organic pollution and to

eutrophication• They are easy to identify• They are’nt movable

This index is based on the presence/absence of some taxa belonging to different groups of sensibility

We can define four groups ( A-B-C-D-) with a gradient of decreasing sensibility

M I S Macrophyte Index Scheme

(Wegher e Turin, 1987)

GROUPS OF SENSIBILITY MACROPHYTES

GROUP A Ranunculs sp

Callitriche hamalata

GROUP B Ranuncul acquatilis

Ranuncul peltatus

Callitriche stagnalis

Callitriche obtusangula

Callitriche platycarpa

Chara spp.

Fontinalis antipiretica

Potamoceton lucens

Potamogeton obtusifolius

Elodea canadensis

Hippuris vulgaris

Apium nodiflorum

Rorippa nasturium-acquaticum

Groups of sensibility Macrophytes

GROUP C Zannichellia palustris

Sparganium spp.

Callitriche hermaphroditica

Potamogeton crispus

Potamogeton natans

Potamogeton perfoliatus

Nuphar lutea

Lemna minor

Lemna trisulca

Enteromorpha sp.

Scirpus lacustris

Myreophyllum spicatum

GROUP D Potamogenton pectinatus

Cladophora glomerata

CLASS OF QUALITY Proportional abundance

Q1 GROUP A Absent

CLASS V GROUP B Absent

GROUP C Scattered emerging

GROUP D Dominant

Q2 GROUP A Absent

CLASS IV GROUP B Absent or scattered

GROUP C Abundant

GROUP D Dominant

Q3 GROUP A Absent

CLASS III GROUP B Common

GROP C Dominant

GROUP D Abundant

Q4 GROUP A Common

CLASS II GROUP B Common or abundant

GROUP C Common

GROUP D Some algae

Q5 GROUP A Dominant

CLASS I GROUP C Scattered

GROUP D Absent

This perennial pondweed have oval floating leaves

and long, narrow, underwater leaves. The

underwater leaves have a broad light green central stripe, the floating leaves

are often oppositely arranged. The underwater leaves are so narrow that

they appear to be stiff leafless stalks, and the

floating leaves often have slightly heart-shaped

bases.

• Submersed leaves: They are alternate and stiff and can be until 50 cm long and up to 2 mm wide.

• Floating leaves: They are alternate and have a colour variable from dark green to copper-coloured; they can be from 6 to 11 cm long and they have a width of 6 cm. their base is heart-shaped and the stalk is longer than the leaf blade.

• Persistent sheaths (stipules): they can be from 6 to 8 cm long and are free from the leaf base

• Stem: It is generally unbranched and nearly cylindrical. It is 2 mm thick.

• Flower: It consists of compact spikes less than 5 cm long on stalks with a length of 12 cm.

• Fruit: It is from 3.5 to 5 mm long; the back is rounded or faintly ridged with a beak of 0.5-1 mm.

• Root: It is fibrous and composed by rhizomes.

• Propagation: It happens through seeds come by large winter buds. These plants sometimes produce tubers.

Family:Family: PotamogetaceaeGenus:Genus: PotamogetonName:Name: Potamogeton coloratusLenght:Lenght: 30cm-1m Origin:Origin: Europe, India, Australia, AfricaTemperature: Temperature: 15°C-22°CpH:pH: 7.00-8.00Hardness:Hardness: 4°d GH-12°d GHSubstratum:Substratum: rich

Charatteristics to recognize it:Charatteristics to recognize it: aquatic plant that cast anchor to the sediment and that has the leaves completely immerse widen or extremely lanceolate; the others that are in surface have large leaves, oval or lanceolate, all enough similar in form and are transpolished. This differentiated caratteristics from Potamogeton Nodosus that has opaque and hard leaves. The plant take a red colouring. The flower is situated out of the water, it is a short spike and it is compact of little flowers a bit strikings. They live only in the water running that flows slowly. They flowers during April-May and also during the summer time.

Curly leaf pondweed grows entirely underwater except for the flower stalk which rises above the water. Curly leaf pondweed has distinctly wavy-edged, crispy olive-green to reddish-brown leaves. It usually grows early in spring and dies back in summer. The leaves of flat-stem pondweed are long and narrow with smooth edges and the sharp-edged stem is flat.

• LEAF: Alternate, all submersed, no leaf stalks. Oblong, stiff, translucent leaves (4-10 cm long, 5-10 mm wide) have distinctly wavy edges with fine teeth and 3 main veins. Sheaths (stipules) up to 1 cm long are free of the leaf base and disintegrate with age

• STEM: branched, up to 90 cm long, somewhat flattened.

• FLOWER: Tiny, with 4 petal-like lobes, in spikes 1-3 cm long on stalks up to 7 cm long.

• FRUIT: Seed-like achene, 4-6 mm long including 2-3 mm beak, back ridged.

• ROOT: Fibrous, from slender rhizomes.

• PROPAGATION: Seeds and creeping rhizomes, over-winters as a hard, brown, bur-like bud with crowded, small holly-like leaves.

• DISTRIBUTION: nearly worldwide

• HABITAT: shallow to deep still or flowing water, tolerant of disturbance.

Life history of Potamogeton crispus is unusual as it flowers and fruits in late spring and early summer, at which time it also produces turions. The plants decay shortly after those structures develop, leaving only fruits and turions, which survive the summer. No one has observed any seed germination, but the turions (referred to as dormant apices) germinate in late summer or fall, and the plants overwinter as small plants only a few cm centimetres in size, even under the ice in northern climates (R. L. Stuckey et al. 1978). Growth then continues as the water begins warming in the spring.

Stems terete, ca. 1 mm thick, or the main stem stouter on deep water forms sparingly branched at the base, becoming freely dichotomously branched above, 3-10 dm long. Leaves all submersed, filiform to narrowly linear, 3-12 cm long, usually 0,2-1 mm wide, 1- to 3-nerved, acute, sometimes wider with obtuse tips early in the growing season or on plants from running water;

Stipules adnate to the base of the leaf blade for 1-3 cm, forming a sheath about as wide as the stem, occasionally wider on the main stem, especially in deep water forms.

Spikes elongate, 1-5 cm long, with 2-5 (7) unevenly spaced floral whorls; h

Peduncles lax, filiform, to 15 cm long. Fruits yellowish to tawny, drying brown, obliquely obovoid, 2,7-4 mm long, rounded on the back, apiculate due to the style beak which is usually 0,3-0,5 mm long.Habitat Shallow to rather deep, fresh to subsaline water of lakes, ponds, marshes, ditches, rivers and streams; common and often abundant.