Analele ştiinţifice ale Universităţii “Al. I. Cuza” Iaşi Tomul LIV, fasc. 2, s.II a. Biologie vegetală, 2008

ON THE OCCURRENCE OF NOLTII HORNEMANN AT THE ROMANIAN COAST OF THE BLACK SEA

V. SURUGIU*

Abstract. The finding of a small Zostera noltii patch (~20 m2) at the Romanian Black Sea coast is reported. The systematics as well as the geographical distribution of this species is briefly reviewed. Some ecological characteristics of this species are also provided. The causes of the declining of Zostera noltii beds at the Romanian coast of the Black Sea are discussed. Key words: beds, Zostera noltii, distribution, Romanian coast, Black Sea

Introduction

The dwarf eelgrass Zostera noltii (Hornem.) Toml. & Posl. belongs to the family Zosteraceae Dumortier, 1829. This family together with the families Cymodoceae, Posidoniaceae, and Hydrocharitaceae forms an ecological group of aquatic angiosperms adapted to live in the marine environment [5]. Representatives of these families are collectively called due to their grass-like appearance. At the Romanian coast, there is also present another species of the genus Zostera, the common eelgrass Z. marina L. [6, 12]. In the past both these eelgrass species covered with a lush growth the bottom of marine lagoons Sinoie, Zmeica and Goloviţa [14]. Isolated patches were reported also at Cape Midia [2] and Agigea [3]. At that time one even spoke about the exploitation of eelgrasses and their use as surrogate for artificial wool, as stuffing material for pillows and mattresses and for packing up eggs, pieces of furniture and other fragile objects [1, 11]. In the last 40 years, due to pollution and eutrophication, seagrasses have declined drastically in abundance, not only at the Romanian coast, but also in the entire Black Sea. The aim of this paper is to reveal the actual status of Zostera noltii beds at the Romanian coast of the Black Sea. Although Zostera noltii is distinguishable from Z. marina, in many cases the authors have cited these simply as “Zostera”, irrespective of whether they refer to one or another species. In order to prevent the confusion between these two species of eelgrass an identification key is provided.

Material and methods

The dwarf eelgrass patch was identified at Mangalia (43°48'18.0"N; 028°35'31.9"E), between 1.3-1.9 m deep, on sandy substrate, in a small embayment formed by a dyke (Fig. 1). The patch is approximately 7 m long and 5 m wide. Samples of Zostera

* “Al. I. Cuza” University of Iaşi, Faculty of Biology, Bd. Carol I, no. 20A, 700506, Iaşi, Romania e-mail: [email protected]

122 noltii were taken by snorkelling on 26th May 2005, 30th June 2005, 4th August 2006, and 8th August 2006. Voucher specimens were herborised and deposited in the Herbarium collection of the Faculty of Biology, “Alexandru Ioan Cuza” University of Iasi. The in situ photographs were taken with a digital ReefMaster DC 310 underwater camera. All the specimens collected were checked against the species description from the speciality literature [6, 9].

Fig. 1 – Location of the Zostera noltii meadow at Mangalia (43°48'18.0"N; 028°35'31.9"E).

Results and discussions

Systematics

Zostera (Zosterella) noltii Hornemann, Fl. Dan. 12(35): 3, tab. 2041 (1832) (Dwarf eelgrass) Fig. 2, 3 auct. non L.–Phucagrostis minor Cavol., Phucagr. Anth. XIV, Pl. 2 (1792) nom. invalid.–Zostera trinervis Stokes, in Bot. Mat. Med. 4: 319 (1812) nom. illeg.–Zostera nana Mertens ex Roth, Enum. Pl. Phan. Germ. 1: 8 (1827) nom. invalid.–Zostera minor (Cavol.) Nolte ex Reichenb., Icon. Fl. Germ. 7: 2 (1845).–Zostera pumila Le Gall in Congr. Sc. France 16: 96, 144 (1850).

Description.–Colour is grass-green. 0.5-2 mm in diameter, with 1-4 roots at each node. Internodes 4-35 mm long. In cross-section the strengthening fibre bundles occur in the innermost layer of the outer cortex of the . Sterile shoots (leaves) alternately arranged and flattened. The leaf sheath at the base clasps the stem but is not fused into a tube, 4-5 cm long. Leaf blades 6-22 cm long and 0.5-1.5 mm wide, with approximately (1)3

123 irregularly spaced veins. The tips of leaves initially rounded, but, as the matures, they become notched (emarginate), often asymmetric. Generative shoots lateral, unbranched or with a few branches near the base, shorter and narrower than the sterile shoots; with 1-6 spathes. Spathal sheath 12-20 mm long and 1.3-2 mm wide. Spadix lanceolate with 4-5 staminate flowers and 4-5 pistillate flowers. Fruit ellipsoid, 1.5-2 mm long; pericarp dark brown. Seeds smooth, white in colour, 1.5-2.0 mm long, excluding the style. 2n = 12. Biology.–Hermaphrodite, perennial herb. Flowering period extends from June to August [6]. In the British Isles the plant retains its leaves throughout the winter. Main method of reproduction is by vegetative growth. However, seedling germination appears to be also important. In the Black Sea peaks of asexual reproduction occur in spring and autumn, when regrowth of the rhizome system is the most intense [7]. Habitat.–Intertidal, between mean high water neap and mean low water neap. In waters with reduced salinity Zostera notii grows deeper and may become permanently submerged. Thus, in the Black Sea the species occurs from 0.6 m down to 8-10 m deep. In Mediterranean the dwarf eelgrass may grow down to 20 m deep. Inhabit sandy or muddy sand substate. Euryhaline species, very tolerant to desiccation. The lower salinity limit is about 15 g l−1. The plant is restricted to sheltered sites such as estuaries, salt marshes, bays and lagoons. At Mangalia it was found in association with Cladophora sericea (Fig. 2). Geographical distribution.–The species is distributed along the Atlantic coasts of Europe and northern Africa, extending from southern Scandinavia (Norway) to the tropic of Cancer (Mauritania and Senegal). It also occurs around the British Isles, in the Baltic Sea, Mediterranean Sea, Adriatic Sea, Black Sea, Sea of Azov, Caspian Sea and Aral Sea [4]. It the Black Sea dwarf eelgrass was recorded in the Sevastopol Bay, along the Caucasian coast (gulf of Anapa, gulf of Novorosiisk, gulf of Gelendjik), gulf of Karkinit, Tendrovsky, and Burgas Bay [8]. At the Romanian coast the presence of Zostera noltii meadows was previously reported at Mamaia, Agigea, Cape Midia, Mangalia, lake Razim, lake Goloviţa and Sinoie lagoon [2, 3, 7, 14].

Key to the Zostera species from the Black Sea

1. Rhizome thin, with 1-4 roots at each node. Leaves 6-22 cm long and 0.5-1.5 mm wide, with one principal vein; leaf-sheaths open with open margins overlapping; leaf tip emarginate. Generative shoot lateral. Retinacula present. Seeds smooth ...... Zostera (Zosterella) noltii

- Rhizome thick, with numerous roots at each node. Leaves 50-150 cm long and 3.0- 7.0(9.0) mm wide, with 3 to 5(9) principal veins; leaf-sheaths closed, tubular, rupturing with age; leaf tip obtuse to slightly mucronate. Generative shoot terminal. Retinacula absent. Seeds with 16-25 longitudinal ridges ...... Zostera (Zostera) marina

In the Black Sea marine phanerogames are represented by 6 species: Zostera marina, Z. noltii, pectinatus, maritima, R. spiralis, and major [8]. However, only the two species belonging to the genus Zostera, commonly

124 known as “eelgrasses”, are considered to be fully confined to the marine environment. The remaining species forms the so-called “eurysaline” group, an ecological group of flowering aquatic plants tolerant of considerable changes in salinity from full-strength seawater to freshwater [5]. The eelgrass biocoenosis is an important element of shallow-water coastal benthic environments [9]. Seagrass beds are among the most productive marine communities. The standing biomass of dwarf eelgrass in the Black Sea ranges from 126 g m−2 (Gulf of Karkinit) to 380 g m−2 (Gulf of Anapa) [12]. The production of Zostera noltii is estimated to 15 g fresh weight/kg/day. As key primary producers, the eelgrasses represent an important source of food for many organisms, especially in the form of detritus. Although, Zostera noltii is grazed directly by waterfowl and by some fish species [6]. The dense, matted root system of eelgrasses stabilise the soft sediments, and thus reduce coastal erosion. Also, seagrass beds increase habitat diversity, providing shelter for a wide variety of marine organisms [2, 9]. Zostera noltii occurs on sedimentary substrata, in areas sheltered from water motion (currents and waves). Because Romanian coast is exposed to north-south alongshore current and to strong winter storms, it offers very few suitable conditions for eelgrass grow. Extensive carpets of eelgrasses were present only in the quiet brackish water lagoons. However, sparse Zostera shrubs were reported in front of Agigea at 0.8-1 m depth [3, 7]. Denser mats were found at Cape Midia [7]. Recently Teacă et al. [13] indicated on the presence of small areas (approx. 30×30 cm) populated by small eelgrass Zostera sp. (most probably Z. noltii) at Mamaia Casino and Mangalia, on a sandy-silty texture substrate, in the proximity of the protective wave-breaking dam. The decline of seagrasses in relatively open areas of the Romanian coast, as well as in the entire Black Sea, is due principally to the eutrophication. The nutrient enrichment of water increased the phytoplankton density, thus decreasing the transparency and diminishing the amount of light that can reach the bottom. The light penetration is also reduced by the siltation of near-shore sediments due to littoral works and to the construction of protective dams. Another cause for the decline of eelgrasses is the collapse of fishing in the Black Sea which reduced grazing on the epiphytes that live on the grass blades. The overgrowth of epiphytes thus prevents or reduces light intensity at the surface of the grass blade. Thus, the blades of the dwarf eelgrass observed at Mangalia were densely covered by various microscopic algae. The freezing of the sea may also have dramatic deleterious effects due to the ice scour [9]. However, the severe frost of the sea occurred during the 2005-2006 winter had no detectable impact upon the size and density of the meadow from Mangalia. As a result of a gradual reduction of salinity in all Romanian littoral lakes from polyhaline to ahaline over the last 40 years, vast fields of eelgrasses have disappeared completely. Because at the Romanian littoral Zostera noltii occurs very sparsely and is threatened to extinction it must be put under protection.

.

125

Fig. 2 – Zostera noltii meadow at Mangalia.

REFERENCES

1. BACALBAŞA-DOBROVICI N., 1951 - Posibilitatea valorificării ierbii de mare (Zostera) în R.P.R. Bul. Inst. Cercet. Pisc., Bucureşti, 10(1): 25-32. 2. BĂCESCU M., MÜLLER G.I., GOMOIU M.-T., 1971 - Ecologie marină. Cercetări de ecologie bentală în Marea Neagră. Analiza cantitativă, calitativă şi comparată a faunei bentale pontice. Ecologie marină, IV, Ed. Academiei R.S.R., Bucureşti 3. BOTEZ M., CĂRĂUŞU S., BOCEC A., CALINICENCO N., 1937 - Le plan de la Station Zoologique Maritime „Regele Ferdinand” d’Agigea – Constantza (Roumanie): Topographie, Biotopes et Biocénoses littoraux. AnnalesScientifiques de l’Université de Jassy, 23(2): 1-4. 4. DEN HARTOG C., 1970 - The Sea Grasses of the World. North-Holland Publishing Company, Amsterdam 5. DEN HARTOG C., KUO J., 2007 - and Biogeography of Seagrasses. In: A.W.D. Larkum, R.J. Orth, C.M. Duarte (Eds.), Seagrasses: Biology, Ecology and Conservation, XVI, Springer Verlag, Berlin 6. GRINŢESCU I., NYÁRÁDY E.I., PAUCĂ A., PRODAN I., ŞERBĂNESCU I., YAHARIADI C., 1966 - Flora Republicii Socialiste.România., XI,Ed. Academiei R.S.R., Bucureşti 7. MIHNEA P., 1965 - Biocenoza faciesului cu Zostera. Lucrare de diplomă, Univ. “Al. I. Cuza” Iaşi, Facultatea de Biologie-Geografie 8. MILCHAKOVA N.A., 1999- On the status of seagrass communities in the Black Sea. Aquatic Botany, 65: 21- 32. 9. PHILLIPS R.C, MEÑEZ E.G., 1988 - Seagrasses. Smithsonian contributions to the marine sciences, No. 34, Smithsonian Institution Press, Washington, D.C.

126 10. ROBERTSON A.I., MANN K.H., 1984 - Disturbance by ice and life history adaptations of the seagrass Zostera marina. Mar. Biol., 80: 131-142. 11. RUDESCU L., 1956 - Cercetări privitoare la exploatarea şi prelucrarea ierbii indigene de mare. Rev. Ind. Lemnului, celulozei şi hârtiei, Bucureşti, 7: 354-359. 12. SKOLKA H., 1977 - Algues macrophytes et Phanerogames des mers saumâtres pontocaspiennes. In: E.A. Pora & M.C. Băcescu (eds.), Biologie des eaux saumâtres de la mer Noire, pp. 59-69. Institut Roumain de Recherches Marines, Constanţa. 13. TEACĂ A., BEGUN T., GOMOIU M.-T., PARASCHIV G.-M., 2006 - The present state of the epibiontic populations to the biocenosis of stone mussels in the shallow water off the Romanian Black Sea coast. Geo- Eco-Marina, 12: 53-66. 14. TEODORESCU-LEONTE R., LEONTE V., MATEI D., ŞOILEANU B., 1956 - Observaţii asupra complexului Razelm-Sinoie în perioada 1950-1952. Ann. Inst. Cerc. Pisc., 1: 1-50.

Acknowledgements I am much indebted to my colleague Dr. C. Mânzu for checking the identification of the species and for helpful advice

Fig. 3 – The habit of Zostera noltii (Hornem.) Toml. & Posl.

127