Associated Editor: Antonio Flores
The benthic macroalgal flora from the eastern Ionian coastal area of the Peninsula Salentina is scarcely studied. This study gives a contribution to the knowledge on its biodiversity in this area, which also includes marine caves, and the geographical distribution of some interesting species. A total of 174 macroalgae (119 Rhodophyta, 27 Ochrophyta, and 28 Chlorophyta) were identified. Six species are first records for the region, one of which,
La flora bentónica marina de la zona costera jónica de la península Salentina, situada en el extremo sudeste de la región italiana de Apulia, está poco estudiada. Este trabajo contribuye al conocimiento de la biodiversidad de algas de esta zona e incluye también cuevas marinas, así como la distribución geográfica de algunas de sus especies más interesantes. Se han encontrado un total de 174 macroalgas (119 Rhodophyta, 27 Ochrophyta y 28 Chlorophyta). Seis especies han sido identificadas por primera vez en la región, una de las cuales,
The evaluation of marine macroalgal diversity of Apulia (southeastern Italy) is particularly interesting due to the vast coastline of this region (994.6 km, including the Tremiti Islands) and its geographical position, acting as a bridge between the east and the west of the Mediterranean basin. An inventory of the Apulian macroalgal flora, based on the available literature, was published more than ten years ago by Cormaci & al. (
The present paper aims to fill up the previously mentioned gap, giving a contribution to the knowledge of the benthic macroalgal flora along the eastern Ionian coastline between Santa Cesarea Terme and Castro. Both the towns are included in the “Regional Natural Park of the Otranto-Santa Maria di Leuca Coast and Tricase Wood” and the coastline strip falls within the area that will soon receive designation as a marine protected area under the name “Peninsula Salentina” (cf.
Several marine karstic caves characterised by sharp physical, chemical and hydrodynamic gradients emphasise the value of this area. The caves represent one of the most important littoral environments in Apulia, the Italian region with the highest density of marine caves. Submerged and partially submerged marine caves are protected by the EC and listed in Annex I of the Habitat Directive 92/43/EEC as a habitat of Community Interest. A few studies have addressed the archeological, paleontological and faunistic importance of such interesting sites and no attempts to inventory macroalgal diversity, with the exception of Grotta delle Viole (Tremiti Islands, Adriatic Sea) (Pignatti & al.,
Thus the present inventory also represents an initial reference that may be useful to the sustainable management of the future marine protected area, as well as a solid framework and a starting point to understand the current status and possible future changes in biodiversity that could hereafter occur on the medium and long term.
The “Peninsula Salentina”, described as the “heel” of the Italian “boot”, represents the easternmost area of Italy, stretching between the Gulf of Taranto and the Otranto Channel. The western coastline is entirely bordered by the Ionian Sea, whereas the eastern one by the Adriatic Sea up to the Capo d’Otranto and the Ionian Sea up to the Capo Santa Maria di Leuca. By convention, the Strait of Otranto represents the boundary between the Adriatic and the Ionian seas. Santa Cesarea Terme is at 6 km south of the Capo d’Otranto and is located on a cliff opposite the Otranto Channel; Castro is located approximately at 8 km south of Santa Cesarea Terme. The investigated coastline is characterised by rocky cliffs of Cretaceous limestone exposed to intense hydrodinamism and occasionally interspersed with short tracts of sandy bottom. The coastline is dominated by a steep slope extending from approximately +120 m to approximately −50 m. The continental shelf of the Italian coasts notoriously reaches its maximum slope in this area, with the 50 m isobath very near the coast. The coastal landscape is also marked by several sea caves, three of which were investigated in the present study: Grotta Grande and Grotta Solfatara at Santa Cesarea Terme, Grotta Palombara at Castro. Grotta Grande (or Sulfurea) (40°2’11” N, 18°27’50” E) is one of the four karstic caves of Santa Cesarea Terme, all characterized by sulphur springs, consisting of a semi-submerged elliptical cavity (length 103 m, maximum depth 1.5 m) with a gentle sloping rocky bed. Grotta Solfatara (40°2’4” N, 18°27’36” E) has a large entrance about 10 m wide and 5 m high, and it is characterized by dense and lactescent waters when high flow periods of the sulphur spring occur, during which the visibility is heavily impacted. Grotta Palombara (“Palummara” or “Picciunara” in reference to the pigeons nesting in the crevices of its stone walls) (40°0’17” N, 18°25’51” E), is a marine cave located at the intersection of two major faults. The huge cavity (length 76 m, width 18 m) has high vaults (height 30 m) that slope abruptly to a 10 m deep flat bed; the cave is characterised by very low light levels due to its narrow entrance.
The field work was performed along an approximately 9.5 km long coastline strip. The sampling covered all seasons, from September 2012 to August 2013, and from April 2013 to February 2014; with this schedule, it was possible to collect species with different life strategies. Samples were collected by SCUBA along 7 transects arrayed perpendicularly to the coastline (5 at Santa Cesarea Terme and 2 at Castro) (
Sampling sites along the Santa Cesarea Terme-Castro coastline.
Abbreviation | Latitude (°N) | Longitude (°E) | |
---|---|---|---|
Santa Cesarea Terme | |||
|
CM | 40°3’8” | 18°28’38” |
|
TS | 40°2’39” | 18°28’31” |
|
Mi | 40°2’17” | 18°28’3” |
|
Ar | 40°2’0” | 18°27’17” |
|
PM | 40°1’45” | 18°26’37” |
Castro | |||
|
PR | 40°0’58” | 18°26’1” |
|
Pa | 40°0’19” | 18°25’52” |
Map of Santa Cesarea Terme-Castro coastline showing sampling sites (CM: Contrada Malepasso; TS: Torre Specchialaguardia; Mi: Miramare; Ar: Archi; PM: Porto Miggiano; PR: Porto Romanelli; Pa: Palombara) and the investigated marine caves (GG: Grotta Grande; GS: Grotta Solfatara; GP: Grotta Palombara).
The sampling inside the caves (
List of macroalgal flora from the Santa Cesarea Terme-Castro coastline and caves. Species reported for the first time either in Italy or in Apulia or noteworthy as second records for the Apulian coasts (see Discussion) are marked with I, A and Sr, respectively. In the Chorology column, phytogeographic elements are named according to Furnari & al. (2010): A: Atlantic; Ab: Boreo-Atlantic; Abt: Boreo-tropical Atlantic; AP: Atlanto-Pacific; APt: Atlanto-Pacific tropical; APct: Atlanto-Pacific cold temperate; At: Atlantic tropical; C: Cosmopolite; CB: Circumboreal; CT: Circumtropical; IA: Indo-Atlantic; IAct: Indo-Atlantic cold temperate; IAt: Indo-Atlantic tropical; IP: Indo-Pacific; M: Mediterranean; SC: Sub-cosmopolitan. The occurrence of every species in the 7 coastline sites (CM, TS, Mi, Ar, PM, PR, Pa) and the 3 caves (GG, GS, GP) is marked *. For the bathymetric distribution, the following abbreviations are used: M = Midlittoral zone; I = Infralittoral zone; uI = upper Infralittoral zone; lI = lower Infralittoral zone.
Chorology | Taxa | Santa Cesarea Terme | Castro | Bathymetric distribution | ||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
CM | TS | Mi | Ar | PM | GG | GS | PR | Pa | GP | |||
IA | * | * | M | |||||||||
M | * | * | * | M | ||||||||
IA | * | I | ||||||||||
M | * | I | ||||||||||
IP | * | * | I | |||||||||
At | * | * | M, I | |||||||||
CT | * | * | * | * | * | I | ||||||
SC | * | * | I | |||||||||
IA | * | * | * | M, I | ||||||||
IA | * | * | * | I | ||||||||
SC | A |
* | * | * | * | M, I | ||||||
Ab | * | * | uI | |||||||||
Ab | * | * | uI | |||||||||
IA | * | * | * | * | lI | |||||||
IA | * | * | M, uI | |||||||||
M | * | * | * | M, uI | ||||||||
SC | * | * | M, I | |||||||||
M | * | I | ||||||||||
M | * | * | M, uI | |||||||||
SC | * | * | * | M, I | ||||||||
SC | * | * | M, I | |||||||||
SC | * | * | M | |||||||||
C | * | * | I | |||||||||
C | * | * | uI | |||||||||
Ab | * | * | * | * | M | |||||||
At | * | * | I | |||||||||
SC | * | * | M | |||||||||
SC | * | * | * | M, uI | ||||||||
SC | * | * | * | M, I | ||||||||
IA | * | * | * | * | lI | |||||||
Abt | * | * | M, I | |||||||||
A | * | * | * | M, uI | ||||||||
SC | * | uI | ||||||||||
C | * | * | * | M, I | ||||||||
IA | * | * | lI | |||||||||
Ab | * | * | * | * | M, uI | |||||||
C | * | * | M, I | |||||||||
IP | * | M, uI | ||||||||||
* | uI | |||||||||||
Ab | * | M, uI | ||||||||||
SC | * | * | M, uI | |||||||||
Ab | * | M | ||||||||||
SC | * | * | M, I | |||||||||
IA | * | uI | ||||||||||
Abt | * | uI | ||||||||||
IA | * | * | * | * | lI | |||||||
SC | * | I | ||||||||||
Abt | * | uI | ||||||||||
CT | * | * | M, I | |||||||||
SC | * | * | * | * | * | M, uI | ||||||
C | * | * | * | * | M, I | |||||||
C | * | * | * | * | M, I | |||||||
CT | * | * | M, uI | |||||||||
CT | * | * | * | M, uI | ||||||||
Ab | * | * | * | I | ||||||||
IA | * | * | * | uI | ||||||||
C | * | M, uI | ||||||||||
Ab | * | * | * | * | uI | |||||||
IAct | * | * | * | * | * | I | ||||||
SC | * | * | lI | |||||||||
* | * | M, uI | ||||||||||
IP | * | * | M, uI | |||||||||
IA | * | * | M, uI | |||||||||
IP | * | * | * | * | uI | |||||||
C | * | * | M, uI | |||||||||
SC | * | uI | ||||||||||
SC | * | uI | ||||||||||
SC | * | uI | ||||||||||
IP | * | * | * | M | ||||||||
Ab | * | M | ||||||||||
Ab | * | * | * | * | * | * | M | |||||
Abt | * | * | M | |||||||||
IA | * | * | * | M, uI | ||||||||
IA | * | * | * | M, I | ||||||||
SC | * | * | * | * | M | |||||||
SC | * | * | * | M | ||||||||
M | * | M, uI | ||||||||||
SC | * | * | * | * | * | M, uI | ||||||
IA | * | * | uI | |||||||||
Ab | * | * | M, uI | |||||||||
M | * | M, uI | ||||||||||
C | * | * | M, uI | |||||||||
SC | * | * | M, uI | |||||||||
* | * | * | M, uI | |||||||||
IP | * | uI | ||||||||||
M | * | * | * | * | lI | |||||||
SC | * | * | * | I | ||||||||
M | * | * | * | I | ||||||||
IA | * | * | * | * | I | |||||||
M | * | * | * | * | * | * | I | |||||
Ab | * | * | * | * | M, uI | |||||||
CB | * | * | * | M, I | ||||||||
Ab | * | * | M, uI | |||||||||
SC | * | * | * | * | uI | |||||||
C | * | * | * | M, I | ||||||||
APct | * | * | uI | |||||||||
Ab | * | * | M, uI | |||||||||
CT | * | M, uI | ||||||||||
Ab | * | * | * | * | uI | |||||||
M | * | * | lI | |||||||||
SC | * | * | M, uI | |||||||||
Abt | * | M | ||||||||||
SC | * | * | * | uI | ||||||||
M | * | * | I | |||||||||
Ab | * | * | * | I | ||||||||
Ab | * | * | * | * | uI | |||||||
Ab | * | * | M, uI | |||||||||
IAt | * | * | * | lI | ||||||||
IA | * | * | M, uI | |||||||||
AP | * | * | * | uI | ||||||||
M | * | lI | ||||||||||
M | * | * | I | |||||||||
Ab | * | * | I | |||||||||
IP | * | * | * | M, uI | ||||||||
C | * | * | * | M, I | ||||||||
IP | * | uI | ||||||||||
Abt | * | M | ||||||||||
CT | * | uI | ||||||||||
CT | * | * | uI | |||||||||
Ab | * | * | * | uI | ||||||||
IA | * | * | uI | |||||||||
C | * | * | uI | |||||||||
CB | * | * | I | |||||||||
SC | * | * | * | * | * | I | ||||||
M | * | * | M, uI | |||||||||
Ab | * | uI | ||||||||||
C | * | * | * | * | * | * | uI | |||||
C | * | * | * | * | I | |||||||
SC | * | * | I | |||||||||
SC | * | I | ||||||||||
SC | * | I | ||||||||||
A | * | * | * | I | ||||||||
APct | * | * | uI | |||||||||
SC | * | * | I | |||||||||
SC | * | * | * | * | * | I | ||||||
Ab | * | * | lI | |||||||||
CT | * | * | * | I | ||||||||
CT | * | * | * | * | * | * | * | I | ||||
SC | * | * | M | |||||||||
C | * | M | ||||||||||
SC | * | * | M, I | |||||||||
SC | * | I | ||||||||||
Ab | * | * | * | I | ||||||||
M | * | * | * | * | I | |||||||
IA | * | * | * | I | ||||||||
AP | * | * | * | * | I | |||||||
IA | * | * | * | M, uI | ||||||||
CT | * | * | uI | |||||||||
AP | * | * | * | M, uI | ||||||||
M | * | * | M, uI | |||||||||
A | * | * | M | |||||||||
SC | * | * | * | uI | ||||||||
IA | * | uI | ||||||||||
IA | * | * | * | M, uI | ||||||||
IA | * | * | uI | |||||||||
IA | * | * | M, uI | |||||||||
IA | * | * | * | M, uI | ||||||||
IA | * | I | ||||||||||
AP | * | * | M, uI | |||||||||
Abt | * | * | * | * | * | I | ||||||
IP | * | * | * | * | * | I | ||||||
At | * | * | I | |||||||||
At | * | M | ||||||||||
SC | * | * | * | M, I | ||||||||
At | * | * | * | * | * | * | I | |||||
CT | * | * | * | * | I | |||||||
APt | * | * | * | lI | ||||||||
M | * | * | lI | |||||||||
C | * | M, uI | ||||||||||
C | * | * | * | M, uI | ||||||||
SC | * | * | M, uI | |||||||||
Ab | * | * | * | M, uI | ||||||||
C | * | M, I | ||||||||||
CT | * | * | M, I |
We preferred to maintain the nomenclature followed by Cormaci & al. (2012) until the synonymy with
We identified 174 taxa (later referred to as “species” for convenience) comprising 119 Rhodophyta (68.4%), 27 Ochrophyta (15.5%), and 28 Chlorophyta (16.1%) (
The three taxa identified at generic level were also interesting and will be put through further deeper investigations: the first is a species of
From a biogeographic point of view, the flora of Santa Cesarea Terme-Castro was characterised by a high incidence of Atlantic elements (42.94%), followed by Cosmopolitan (31.76%) and Mediterranean elements (11.18%). A lower incidence was shown by the Circumtropical (7.06%), the Indo-Pacific (5.88%) and the Circumboreal (1.18%) elements (
Of the 174 taxa, the following records are noteworthy and interesting from a phytogeographic point of view:
Vegetative thalli (
Three species of the genus
Moderately calcified fertile thalli, pink coloured with darker tips, up to 50 mm high, were collected in spring and summer. The following features were useful for species identification: i) morphology of cortical assimilatory filaments composed of oval cells becoming gradually shorter and slender (
Plants were collected at a depth of approximately 2 m in sheltered places. Thalli forming scattered feathery tufts bore typical gametangia, separated from the supporting branches by a plug and with one apical papilla (
Female plants were collected at three sites from Santa Cesarea Terme; thalli were moderately to heavily calcified on both surfaces; hair lines alternating between lower and upper surfaces were unequally spaced (
The present study documented approximately a 30% of the species previously recorded for the Apulian region. A comparison of the number of species collected during the current survey with the corresponding numbers for other Apulian localities indicates that the macroflora of Santa Cesarea Terme and Castro is relatively rich if the limited extent (approximately 9.5 km) of the investigated area is considered. All the species recorded in the past from Santa Cesarea Terme (Huvé & al.,
The floras of the two caves of Santa Cesarea Terme, Grotta Grande and Grotta Solfatara, were different from that of Grotta Palombara at Castro. This could be explained by the peculiar characteristics of the first two caves (i.e., very low light conditions, the presence of suspended sulphureous material, which strongly reduces water transparency, and the unusual chemical composition of the seawater), which favour the predominance of red algae, primarily Corallinales.
The R/P index (Rhodophyceae/Phaeophyceae) (Feldmann,
Generally, the marine flora of the surveyed coastline has the following principal characteristics: i) extensive communities of Corallinales, especially in the two sulphureous caves, that are ecologically significant, allowing colonisation by many invertebrates and promoting an increasing biodiversity through the construction of coralligenous habitats; ii) limited presence of species with a wide ecological valence; iii) occurrence of a restricted belt of the protected species
Despite the presence of human-driven transformation, primarily associated with services and accommodation structures, this coastline maintains a good ecological status and may represent an example of almost-intact ecosystem and an ideal reference area for comparison with areas having higher levels of pollution.
We thank Drs. G. Lazzo, C.I. Delle Foglie, G. Lapenna and A. Manghisi for their kind assistance with the field work and Prof. G. Furnari for his critical reading of the manuscript. This work was supported by a grant from the University of Bari “A. Moro”.