Thursday, 3 December 2015
Posidonia oceanica (L.) Delile - Ποσειδωνία η ωκεάνειος
Posidonia oceanica (commonly known as Neptune Grass or Mediterranean tapeweed) is a seagrass species that is endemic to the Mediterranean Sea. It forms large underwater meadows that are an important part of the ecosystem. The fruit is free floating and known in Italy as "the olive of the sea" (l'oliva di mare). Balls of fibrous material from its foliage, known as egagropili, wash up to nearby shorelines.
P. oceanica is a flowering plant which lives in dense meadows or along channels in the sands of the Mediterranean. It is found at depths from 1–35 metres (3.3–114.8 ft), according to water clarity. Subsurface rhizomes and roots stabilize the plant while erect rhizomes and leaves reduces ilt accumulation.
The leaves are ribbon-like, appearing in tufts of 6 or 7, and up to 1.5 metres (4.9 ft) long. Average leaf width is around 10 millimetres (0.39 in). The leaves are bright green, perhaps turning brown with age, and have 13 to 17 parallel veins. The leaf terminus is rounded or sometimes absent because of damage. Leaves are arranged in groups, with older leaves on the outside, longer and differing in form from the younger leaves they surround.
The rhizome type stems are found in two forms: one growing up to 150 centimetres (59 in) beneath the sand and the other rising above the sand. All stems are approximately 10 millimetres (0.39 in) thick and upright in habit. This arrangement of the rhizomes eventually forms a mat; the surface contains the active parts of the plant, whereas the center is a dense network of roots and decomposing stems.
The flowering plant's common name is Neptune grass. In 2006 a huge clonal colony of P. oceanica was discovered south of the island of Ibiza. At 8 kilometres (5.0 mi) across, and estimated at around 100,000 years old, it may be one of the largest and oldest clonal colonies on Earth
This species is found only in the Mediterranean Sea where it is in decline, occupying an area of only about 3% of the basin. This corresponds to a surface area of about 38,000 square kilometres (15,000 sq mi). Posidonia grows best in clean waters, and its presence is a marker for lack of pollution. The presence of Posidonia can be detected by the masses of decomposing leaves on beaches. Such plant material has been used for composting, but Italian laws prohibit the use of marine algae and plants for this purpose.
The genus Posidonia is named after Poseidon, the Greek god of the seas, while oceanica refers to its former wide distribution. Carl Linnaeus gave the first botanical description of this species in Systema Naturae, although the genus was then named Zostera. The APG system (1998) and APG II system (2003) accept the genus as constituting the sole genus in the family Posidoniaceae, which it places in the order Alismatales, in the clade monocots. The Angiosperm Phylogeny Website concludes that the three families Cymodoceaceae, Posidoniaceae and Ruppiaceae form a monophyletic group. Earlier systems classified this genus in the family Potamogetonaceae or in the family Posidoniaceae but belonging to order Zosterales.
To date 51 natural products have been reported from P. oceanica, including natural phenols, phenylmethane derivatives, phenylethane derivatives, phenylpropane derivatives and their esters, chalkones, flavonols, 5-alpha-cholestanes, and cholest-5-enes. Many of the compounds reported for P. oceanica were, however, not detected by appropriate phytochemical methods and some most probably represent artifacts and are not genuine natural products of P. oceanica.
From Wikipedia, the free encyclopedia
Underwater photos by Kostas Aristeidou
Noble pen shell - Pinna nobilis - Linnaeus, 1758 - Πίννα - Cyprus
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| Photo by Costas Constantinou |
Family Pinnidae
Pinna nobilis, common name the noble pen shell or fan mussel, is a large species of Mediterranean clam, a marine bivalve mollusc in the family Pinnidae, the pen shells. It reaches up to 120 cm (4 ft) of shell length
The bivalve shell is usually 30–50 cm (1.0–1.6 ft) long, but can reach 120 cm (4 ft). Its shape differs depending on the region it enhabits. Like all pen shells, it is relatively fragile to pollution and shell damage. It attaches itself to rocks using a strong byssus composed of many silk-like threads which used to be made into cloth. These keratin fibres that the animal secretes by its byssus gland are even 6 cm (2.4 in) long. The inside of the shell is lined with brilliant mother-of-pearl.This species is endemic to the Mediterranean Sea, where it lives offshore at depths ranging between 0.5 and 60 m (1.6 and 196.9 ft). It could be found buried beneath soft-sediment areas (fine sand, mud, often anoxic)
This species is the origin of sea silk, which was made from the byssus of the animal.
In recent years, Pinna nobilis has become threatened with extinction, due in part to fishing, incidental killing by trawling and anchoring, and the decline in seagrass fields; pollution kills eggs, larvae, and adult mussels. The noble pen shell has been listed as an endangered species in the Mediterranean Sea. The European Council Habitats Directive 92/43/EEC, on conservation of natural habitats and the wild fauna and flora, proclaims that P. nobilis is strictly protected (by the Annex IV of EEC, 1992)- all forms of deliberate capture or killing of fan mussel specimens are prohibited by law.
As part of the Costa Concordia disaster recovery effort going on in Italy (2012), a group of about 200 Pinna nobilis was manually relocated to a nearby area due to the threat posed by subsequent engineering work.From Wikipedia, the free encyclopedia
Η πίννα (Pinna) (γράφεται και πίνα), είναι γένος δίθυρων μαλάκιων της οικογένειας των Πιννιδών και της τάξης των Ανισομυαρίων. Ζει στις εύκρατες και στις θερμές θάλασσες. Μοιάζει με τεράστιο μύδι. Το όστρακό της αποτελείται από λεπτά και πλατιά ελάσματα, τα οποία είναι ενωμένα στην κορυφή τους, ώστε να ανοίγουν και να κλείνουν Το ζώο, το οποίο τρώγεται χωρίς να είναι ιδιαίτερα εύγευστο, χρησιμοποιείται κυρίως ως δόλωμα στο ψάρεμα. Στο όστρακο της πίννας σπάνια σχηματίζονται μαργαριτάρια, τα οποία όμως δεν έχουν ιδιαίτερη οικονομική αξία.
Το μήκος του ζώου φτάνει τα 70 εκατοστά. Τα όστρακα της πίννας είναι λεπτά, σε σχήμα τρίγωνο και μυτερά στο ένα άκρο, ενώ από το άλλο είναι στρογγυλευμένα. Στο εξωτερικό μέρος έχουν χρώμα κίτρινο και από μέσα παρουσιάζουν ελαφρύ ιριδισμό.
Στον ελληνικό χώρο και ιδίως στη Χαλκιδική (στις Νέες Φώκιες) απαντάται η πίννα η ευγενής. Επίσης στη Μεσόγειο ζει και η πίννα η κτενοειδής, εδώδιμη. Το μήκος της είναι περίπου 20 εκατοστά. Αρκετά είδη συμβιώνουν με καβούρια (πιννοθήρες, γνωστά και ως πιννοκαβούρια), τα οποία βρίσκουν προστασία στην κοιλότητά της. Σε αντάλλαγμα, την προειδοποιούν να κλείσει τα ελάσματά της όταν υπάρχει κίνδυνος.
Εκτός από την αλιεία, όπου χρησιμεύει ως δόλωμα, η πίννα χρησιμοποιείται και για την κατασκευή μεταξένιων υφασμάτων. Συγκεκριμένα, η βύσσος της πίννας χρησιμοποιείται για κατασκευή τέτοιων υφαντών στην νότια Ιταλία και στη Σικελία. Επίσης, από τη βύσσο κατασκευάζουν κάλτσες και γάντια. Το είδος δεν κινδυνεύει άμεσα με εξαφάνιση, αλλά απαιτείται η λήψη μέτρων για την προστασία της.
Από τη Βικιπαίδεια, την ελεύθερη εγκυκλοπαίδεια
Underwater photos at Akrotiri by Kostas Aristeidou
Wednesday, 2 December 2015
Atlantic blue tang - Acanthurus coeruleus - Bloch & J. G. Schneider, 1801 - Cyprus
Unexpected alien species in Cyprus waters
Acanthurus coeruleus is a surgeonfish found commonly in the Atlantic Ocean. It can grow up to 16 inches (41 cm) long. Common names include Atlantic blue tang, blue barber, blue doctor, blue doctorfish, blue tang, blue tang surgeonfish, yellow barber, and yellow doctorfish.
Acanthurus coeruleus is common off the coast of Florida, The Bahamas, and other places in the Caribbean Sea, including Bonaire. Blue Tangs are very common in Belize and especially Ambergris Caye. They are also common in the Gulf of Mexico. They are also found south to Brazil and north to New York.
.Although the body of the reef fish can vary in shade from light to dark blue, the dorsal, anal and caudal fins are golden blue. As juveniles, the edges on their dorsal and anal fins and the rings around their eyes are purple-blue, blue or blue-green. Their colors change during growth from a yellow juvenile, yellow tailed blue subadult and the blue adult phase.
Atlantic blue tangs inhabit coral reefs and inshore grassy and rocky areas, where there is a high prevalence of algae. They are herbivorous, and their diet consists only of algae. They eat the algae from the reefs in which they reside, as well as off the bodies of surrounding fish. By eating the algae off of other fish, the blue tang serve as cleaners for them. With the decline in the Diadema antillarum (sea urchin) population, the blue tang population increased since the algal resources that the two animals usually competed for were more abundant.
Juvenile blue tangs eat continuously and feed heavily. This heavy feeding requirement is due to their poor utilization of food resources. The blue tang's stomach and intestinal lining are proficient at absorbing crushed cellular content, but are not very effective at processing cellulose. This digestive system inefficiency leads blue tangs to spend more time and resources on foraging on a very abundant and fast-growing food source in close proximity. This close proximity to an abundant food source allows for continuous foraging.
Food distribution, density, and accessibility can determine population density and territory size in blue tangs. Territories with low biogenic structure are larger than those of higher biogenic structure. Since the algal food resources are less dense in low-biogenic structured areas, these territories would have to be larger in order to include the necessary amount of food. This is in accordance with the Ideal free distribution model. This model states that competitors should adjust their distribution in accordance with habitat quality such that each individual will gain the same amount of resources.
Photos and video Mandria, Akrotiri Gata and Akrotiri Zevgari by Kostas Aristeidou
Marine Biodiversity Records, page 1 of 3. # Marine Biological Association of the United Kingdom, 2012 doi:10.1017/S1755267212001042; Vol. 5; e116; 2012 Published online
Unexpected alien species in Cyprus waters: Acanthurus coeruleus (Actinopterygii: Acanthuridae)
joachim langeneck1 , massimiliano marcelli2 and helmut carl simak3
1 Universita` di Pisa, Dipartimento di Biologia, Unita` di Biologia Marina e Ecologia, Via Derna 1, I-56126 Pisa, Italy, 2 Universita` di Roma ‘La Sapienza’, Dipartimento di Biologia e Biotecnologie ‘Charles Darwin’, Piazzale Aldo Moro, 9–00185, Rome, Italy, 3 Waidmannsforferstrasse 16/7 A-9020 Klagenfurt,
Austria In December 2011 a specimen of the blue tang surgeonfish Acanthurus coeruleus was observed in the waters of Cyprus. As this species typically lives in the tropical western Atlantic Ocean, its presence in the Mediterranean Sea is very likely to be related to human activities. Speculated ways of introduction in the Mediterranean Sea are discussed.
Keywords: alien species, blue tang surgeonfish, Acanthurus coeruleus, climatic changes Submitted 30 September 2012; accepted 25 October 2012
INTRODUCTION
Among the family Acanthuridae only one species has been recorded from the Mediterranean Sea so far, namely Acanthurus monroviae Steindachner, 1876, which was reported first from southern Spain (Crespo et al., 1987) and later from Israel’s Mediterranean coast (Golani & Sonin, 1996). In the years 2001–2002 it was observed quite regularly along the Algerian coast (Hemida et al., 2004). Here we report the first occurrence of the blue tang surgeonfish Acanthurus coeruleus Bloch & Schneider, 1801 in the Mediterranean Sea and some ways the species may have been introduced are discussed.
Acanthurus coeruleus is a surgeonfish found commonly in the Atlantic Ocean. It can grow up to 16 inches (41 cm) long. Common names include Atlantic blue tang, blue barber, blue doctor, blue doctorfish, blue tang, blue tang surgeonfish, yellow barber, and yellow doctorfish.
Acanthurus coeruleus is common off the coast of Florida, The Bahamas, and other places in the Caribbean Sea, including Bonaire. Blue Tangs are very common in Belize and especially Ambergris Caye. They are also common in the Gulf of Mexico. They are also found south to Brazil and north to New York..Although the body of the reef fish can vary in shade from light to dark blue, the dorsal, anal and caudal fins are golden blue. As juveniles, the edges on their dorsal and anal fins and the rings around their eyes are purple-blue, blue or blue-green. Their colors change during growth from a yellow juvenile, yellow tailed blue subadult and the blue adult phase.
Atlantic blue tangs inhabit coral reefs and inshore grassy and rocky areas, where there is a high prevalence of algae. They are herbivorous, and their diet consists only of algae. They eat the algae from the reefs in which they reside, as well as off the bodies of surrounding fish. By eating the algae off of other fish, the blue tang serve as cleaners for them. With the decline in the Diadema antillarum (sea urchin) population, the blue tang population increased since the algal resources that the two animals usually competed for were more abundant.
Juvenile blue tangs eat continuously and feed heavily. This heavy feeding requirement is due to their poor utilization of food resources. The blue tang's stomach and intestinal lining are proficient at absorbing crushed cellular content, but are not very effective at processing cellulose. This digestive system inefficiency leads blue tangs to spend more time and resources on foraging on a very abundant and fast-growing food source in close proximity. This close proximity to an abundant food source allows for continuous foraging.
Food distribution, density, and accessibility can determine population density and territory size in blue tangs. Territories with low biogenic structure are larger than those of higher biogenic structure. Since the algal food resources are less dense in low-biogenic structured areas, these territories would have to be larger in order to include the necessary amount of food. This is in accordance with the Ideal free distribution model. This model states that competitors should adjust their distribution in accordance with habitat quality such that each individual will gain the same amount of resources.
According to this model, there should be a lower density of blue tangs on low-biogenic structured territories compared to higher-biogenic structured territories where there is a higher abundance of food. In both territories, each individual will receive similar amounts of resources due to competition. There is no significant difference in feeding rates of blue tangs on each type of territory, meaning that those in larger, uncolonized, and low density territories can match the resources of those in smaller high density territories.Από τη Βικιπαίδεια, την ελεύθερη εγκυκλοπαίδεια
Photos and video Mandria, Akrotiri Gata and Akrotiri Zevgari by Kostas Aristeidou
Marine Biodiversity Records, page 1 of 3. # Marine Biological Association of the United Kingdom, 2012 doi:10.1017/S1755267212001042; Vol. 5; e116; 2012 Published online
Unexpected alien species in Cyprus waters: Acanthurus coeruleus (Actinopterygii: Acanthuridae)
joachim langeneck1 , massimiliano marcelli2 and helmut carl simak3
1 Universita` di Pisa, Dipartimento di Biologia, Unita` di Biologia Marina e Ecologia, Via Derna 1, I-56126 Pisa, Italy, 2 Universita` di Roma ‘La Sapienza’, Dipartimento di Biologia e Biotecnologie ‘Charles Darwin’, Piazzale Aldo Moro, 9–00185, Rome, Italy, 3 Waidmannsforferstrasse 16/7 A-9020 Klagenfurt,
Austria In December 2011 a specimen of the blue tang surgeonfish Acanthurus coeruleus was observed in the waters of Cyprus. As this species typically lives in the tropical western Atlantic Ocean, its presence in the Mediterranean Sea is very likely to be related to human activities. Speculated ways of introduction in the Mediterranean Sea are discussed.
Keywords: alien species, blue tang surgeonfish, Acanthurus coeruleus, climatic changes Submitted 30 September 2012; accepted 25 October 2012
INTRODUCTION
Among the family Acanthuridae only one species has been recorded from the Mediterranean Sea so far, namely Acanthurus monroviae Steindachner, 1876, which was reported first from southern Spain (Crespo et al., 1987) and later from Israel’s Mediterranean coast (Golani & Sonin, 1996). In the years 2001–2002 it was observed quite regularly along the Algerian coast (Hemida et al., 2004). Here we report the first occurrence of the blue tang surgeonfish Acanthurus coeruleus Bloch & Schneider, 1801 in the Mediterranean Sea and some ways the species may have been introduced are discussed.
MATERIALS AND METHODS
On 1 December 2011, during a SCUBA dive in the vicinity of
Xilofagou (south-eastern Cyprus: 34857′
41′′N 33849′
48′′E), a
single juvenile specimen of Acanthurus coeruleus (Figure 1)
was observed, and several photographs were taken. The specimen
(approximately 8 cm total length) showed up at a depth
of 4–5 m over rocky bottom covered by calcareous algae
among some individuals of Thalassoma pavo (Linnaeus,
1758), Sparisoma cretense (Linnaeus, 1758), Chromis
chromis (Linnaeus, 1758) and Sargocentron rubrum
(Forsska˚l, 1775). The morphological characters match those
of a juvenile specimen of A. coeruleus: although many surgeonfishes
have yellow juvenile phases, only A. coeruleus
and Acanthurus pyroferus Kittlitz, 1834 show electric blue
fin edges and a blue ring around both eyes (Lieske & Myers,
1995). However, the two species can be easily distinguished,
as A. coeruleus shows 9 dorsal spines, whereas A. pyroferus
shows only 8. As the observed specimen has 9 dorsal spines
it should be clearly identified as A. coeruleus.
A second observation of a conspecific specimen took place
two days later on the 3 December 2011 near Ayia Napa, about
12 km from the first sighting (34859′
11′′N 33857′
53′′E).
Although the photographs taken at this time are not so
clear, the fish in the photograph appears to be A. coeruleus
as well.
DISCUSSION
Acanthurus coeruleus usually lives in the western Atlantic
Ocean, mainly in tropical waters; it has been recorded from
islands of the Mid-Atlantic Ridge too, especially from
Ascension Island (Cadenat & Marchal, 1963; Lubbock,
1980). The present record reports for the first time the presence
of this species in the Mediterranean Sea; it is not clear
whether the specimen observed on the 3 December is the
same as the one observed on the 1 December 2011. The presence
of at least one juvenile specimen in the Mediterranean
Sea could be explained by three processes: (i) arrival in the
Mediterranean Sea through the Atlantic Ocean unrelated to
human activities; (ii) introduction by shipping of eggs or
larvae; and (iii) release of a captive specimen. The establishment
of a tropical Atlantic fish first in the eastern
Mediterranean, and its subsequent westward spreading, is
already known for the fangtooth moray eel Enchelycore
anatina (Lowe, 1839) (Ben Tuvia & Golani, 1984; Bitar
et al., 2003; Guidetti et al., 2012)—probably due to the
warmer waters of the eastern basin; however, this possibility
seems to be unlikely for Acanthurus coeruleus because of the
huge distance to travel, although the larval phase of this
species has a planktonic life span of 45 –70 days (Rocha
et al., 2002) which seems to be sufficient for crossing the
Atlantic Ocean and the Mediterranean Sea from west to east.
The second possibility is the introduction by shipping
within ballast water containing larval and juvenile specimens.
This kind of introduction of species with a distribution range
very far from the Mediterranean Sea is already known
(Rodrı`guez & Sua`rez, 2001; Galil, 2006) for bony fishes
(Goren et al., 2009; Schembri et al., 2010); the long pelagic
life of the larval stage accords with this hypothesis. The colonization
via ballast water is known for western Atlantic
species, for example Pinguipes brasilianus (Cuvier &
Valenciennes, 1829) (Orsi Relini, 2002) and the hermatypic
coral Oculina patagonica De Angelis, 1908 (Zibrowius, 1974;
Fine et al., 2001).
A likely possibility as well seems to be the escape of a young
specimen from captivity, as the species is commonly traded as
aquarium fish. This way of introduction in the Mediterranean
has been speculated for the exotic fishes Platax teira (Forsska˚l,
1775) (Bilecenoglu & Kaya, 2006) and Pterois miles (Bennett,
1803) (Golani & Sonin, 1992); the latter has been also introduced
through aquarium escapees along the western
Atlantic Coast, where it is currently considered as a highly
invasive species (Morris et al., 2009). However, as these
species commonly occur in the Red Sea, an arrival through
the Suez Canal cannot be excluded. For a third species,
Scatophagus argus (Linnaeus, 1766), whose native range
covers the Indian Ocean (excluding the Red Sea) and the
Pacific Ocean, the most likely explanation of the presence in
the Mediterranean Sea seems to be the aquarium escape
(Zammit & Schembri, 2011). Nevertheless, at present, no
documented introduction of bony fishes via aquarium trade
is known in the Mediterranean. Another two western
Atlantic species, namely Paranthias furcifer (Valenciennes,
1828) and Holacanthus ciliaris (Linnaeus, 1758), were recently
reported, on the basis of single specimens, from a little bay in
the central part of the eastern Adriatic Sea (Dragicˇevic´ &
Dulcˇic´, 2012); these authors considered their presence
related to the long rest of an oil platform coming from the
Gulf of Mexico in a Croatian shipyard. Such an explanation,
however, is not plausible for the present record.
Apart from the way of introduction, about which only suggestions
can be made, Acanthurus coeruleus is a highly thermophilic
species; its survival in late autumn in the eastern
part of the Mediterranean Sea is remarkable, probably
related to the trend of global warming and especially to the
warming of the Mediterranean waters (Francour et al.,
1994). This record of A. coeruleus in the Mediterranean Sea
is probably an accident: the establishment of this western Atlantic species in the Mediterranean seems unlikely
ACKNOWLEDGEMENTS
We are very grateful to B. Dragicˇevic´ and J. Dulcˇic´ for providing
literature and to the anonymous referees for their valuable
comments and corrections.
Tuesday, 1 December 2015
Monday, 30 November 2015
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