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Open Access item La Cova des Coll (Felanitx, Mallorca): espeleogènesi, geomorfologia, fauna i conservació
Fornós, Joan J.
Uriz, María Jesús
|Publisher:||Universidad de las Islas Baleares|
|Citation:||Endins 27 : 141-186 (2005)|
|Abstract:||[EN]The Cova des Coll (Felanitx) has a current survey length of 7,020 m, of which 5,529 m
are subaquatic. The cave has two natural entrances and two artificial wells also connect with
it. One of the natural entrances connects with the bay of Portocolom and the other is inland.
Part of the cave lies below an urbanised area of Portocolom.
The principal characteristic which highlights the geomorphology of the cave is the
almost complete absence of speleothems due to the corrosive effects of the water and the
large abundance of corrosion morphologies, which we have catalogued by form. It appears
that the level of destruction of speleothems decreases moving inland and moving downward.
The sediments of the Cova des Coll have two clearly definable units identifiable both by
colour and by mineral content: an upper layer whose composition is mainly carbonate where
calcite dominates and its colour is lighter and a lower one where silicic components are its
principal characteristic along with its reddish tone. There are important differences moving
through the cave, especially between the sections closer to the sea, which lack the upper
layer, and those more inland, which are formed by more or less sandy mud with high levels
of clays. In addition to these accumulations which can be considered as being earlier, red
muddy accumulations have been seen on the walls in many places, which show signs of
erosion and which represent earlier stages of in-filling during different environmental conditions
to those now.
The water-column profiles of salinity and temperature have four well-defined bands.
The directness of communication with the bay determines the currents which distort the typical
profile, except at greater depths. These depths are less effected by mass movements of
water into and out of the cave as the bay level changes with barometric changes. An important
flow of water in the interior chambers has been observed, where the water rises up the
chamber walls owing to the different densities toward the surface of the water column.
The faunal distribution, including salinity preferences, has been studied in the different
sections of the cave. 15 species of non-arthropod invertebrates have been catalogued and
their distribution is closely related to their distance inland from the sea. 7 sponges have been
classified, three of which are not worthy for their first sighting along the Spanish coast.
Amorphinopsis pallescens, if not a new species, is the second sighting of this species in the
Mediterranean. The sponges have robust spicules, which indicate a high level of available
silica. The studies carried out show evidence that the source of this is the sediment. Of the
two polychaeta Found Bispira viola constitutes the first sighting of the species for the Iberian
Peninsula and the Balearic Islands.
Twenty-nine species of crustaceans are reported from the cave, 5 of them corresponing
to harpacticoid copepods and 1 to an ostracod. The rest belong to diverse groups such as
leptostracans, decapods, amphipods, isopods, mysids, thermosbaenaceans, and calanoid,
misophrioid and cyclopoid copepods. 61% of the species are stygobionts (i.e., obligate
groundwater dwellers); the rest correspond to littoral marine species characteristic of suprabenthic
or crevicular marine habitats, preadapted in some way to live in caves, or are neritic
species characteristic of the plankton of bays and harbours. Four of the stygobiont species
are new to Science. 9 of the species found in the cave are Balearic endemics.
Following the detailed study of this cave it has become apparent the urgent need to
establish effective protective measures which will permit the conservation of this natural and
culturally valuable patrimony.|
|Description:||47 páginas, 42 figuras, 6 tablas|
|Publisher version (URL):||http://www.raco.cat/index.php/Endins/article/view/122522/169645|
|Appears in Collections:||(CEAB) Artículos|
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