IMG_0001 Fig. 1.Geographical location and sampling stations (E1, E2 and E3) of the study area.

Antonio Vega Torres, Frank A. Ocaña Borrego, Alejandro Fernández Velázquez, Carmen R. Zayas Herrera & Elier A. Córdova García.

Centro de Investigaciones y Servicios Ambientales y Tecnológicos de Holguín. Calle 18 s/n. Rpto. “El Llano”, Holguín, Cuba. CP 80100.

*corresponding author: vega@cisat.cu*

Abstract: From the rocky shore of Gibara, north eastern Cuba, 24 species of molluscs were recorded. Families Littorinidae and Neritidae had higher number of species. Fourteen new records of molluscs for the coast of Gibara are added. The most abundant species were the gastropods Echinolittorina ziczac (26,7 %), Tectarius antoni  (25 %) and Nodilittorina mespillum  (19,9 %).  Species richness varied among sampling stations. Higher species richness were found in the supralittoral zone. The intertidal zone reached a maximum abundance of 30 ind./m2 whereas the supralittoral zone reached maximum values of 57 ind./m2. Exposed rocky shore presented higher species richness and abundance than the sheltered ones, these differences could be related with physical factors such as wave action and substrate features. Cluster analysis showed a clear separation among sheltered and exposed zones and between intertidal and supralittoral zones. Species clustered in two groups segregated by the vertical distribution in the shore.

Introduction

Studies about marine molluscs from the coast of Holguín province have been carried out only at six localities (Torres, 1987, 1988; Espinosa, 1987; Espinosa & Rams, 1988; Vega et al., 2004; Ocaña et al., 2010), and most of them have focussed on making a checklist and to describe associated biotopes. The west shore in Holguín constitutes one of the most extensive and morphologically complex rocky shores in Cuba. It is located between the Gibara bay and Caletones beach. Part of this shore belongs to the Caletones Ecological Reserve, a protected area of national significance; nevertheless most of the knowledge about molluscs is solely restricted to zoological collections and unpublished reports.

For the moment a few studies has deal with seashells and there’s a gap of information about spatial structure and distribution of molluscs in the rocky shore. The aim of the present paper is to describe aspects about the abundance and distribution of intertidal and supralittoral molluscs from the rocky shore of Gibara.

MATERIALS AND METHODS

 

Study area: the study area is located in Gibara municipality (21o12´35” N, 76o14´42” W) (Fig. 1). The coast is abrasive composed by a calcareous hard substrate of 15 km in length alternating with short sectors of sands and rocks.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Sampling sites: sampling was carried out at the beginning of the rainy season of 2009. We separated the coast in two different categories in exposed and sheltered depending on the effects of waves. Selection of sampling sites were based on a priori field trip trying to identify sites with contrasting morphology and covered by living organisms. Accessibility and safety were took it into account.

Three stations were selected (Fig. 1):

Station E1. Punta Vigía (21012´25.1´´N y 76013´36.8´´W). Sheltered coast located in the Caletones Ecological Reserve. The intertidal zone is wide and flat and the bottom is composed of hard substrate with patches of sediment were many seaweeds growths. In this site are abundant corals of  species Porites divaricada and the sea urchin Echinometra lucunter. The supralittoral zone presents pebbles and the fauna is not abundant. In this station two transects were established.

Station E2. Playa María Velázquez (210 10´13.2´´N y 760 09´06.6´´W). We selected a transect in a small sheltered part and two transects in an exposed part. The sheltered area has very low influence of waves and the flora and fauna richness is very low, the supralittoral zone is very abrupt and exists many debris and oil spots. In the exposed area the intertidal zone is narrow and some coralsof the genus Porites, Diploria, Dichocoenia and Siderastrea exists, the spcies richness of seaweeds is very low. Supralittoral zone is about 20m in length.

Station E3. Punta Goleta (210 10´13.2´´N y 760 09´06.6´´W). Very exposed, located near of Gibara town. Three transects were established. Intertidal zone is very narrow and is covered mostly by green seaweeds. Supralittoral zone is about 20m in length.

Sampling: we followed a stratified sampling design. A 0.25 m2(1.0 m x 0.25 m) quadrat were used, being placed ramdomly over the substrate along every transect from the intertidal to the upper part of the supralittoral zone, taking at least three replicates per zone. Most of the living animals were identify in situ to reduce stress and mortality. The animals that we can’t identify in the field were fixed in 10% formalin and preserved in 70% ethanol and carried out to the laboratory where   identification were possible using a microscope and the works of Abbott (1974) and Espinosa et al. (1994). Collected material were deposited in the malacological collection of the natural history museum “Carlos de la Torre y Huerta” in Holguín city.

Species richness was determined based on the number of species found (S). The taxonomic similarity among stations, zones and species was estimated by the Bray-Curtis index (Bray & Curtis, 1957) with a presence-absence transformation of the raw data and dendograms were constructed using the simple average method.

RESULTS

Specific composition

A total of 2038 individuals of 24 species were recorded. Species are included in three classes (Polyplacophora, Gastropoda and Bivalvia), seven orders, 13 families and 19 genera (Table 1). Families of gastropods with larger number of species were Littorinidae (6) and Neritidae (5). The best represented genus was Nerita Linné, 1758 with three species. In the Polyplacophora the genus Chiton Linné, 1758 was represented with two species while bivalve molluscs were represented by only one genus per family. Two families of gastropods and three of bivalve are represented with only one species (Table 3). In despite there’s not any new record for Cuba, 14 species in the checklist for coastal zone of Gibara are here added (Table 3).

Table 1. Taxonomic composition of the malacological fauna from the rocky shore of Gibara.

Class Order Family Genus Species
POLYPLACOPHORA NEOLORICATA

1

2

3

GASTROPODA VETIGASTROPODA

1

1

2

NERITOPSINA

1

3

5

SORBEOCONCHA

6

9

10

BIVALVIA ARCOIDA

1

1

1

MYTILOIDA

1

1

1

PTERIOIDA

2

2

2

TOTAL

13

19

24

The species Nerita tessellata (Gmelin, 1791), Fissurella barbadensis (Gmelin, 1791) and Chiton squamosus (Linné, 1764), were registered at the three sampling stations. The most abundant species among stations were the gastropods Echinolittorina ziczac (Gmelin, 1791) (26,7 %), Tectarius antoni (Philippi, 1846) (25 %) and Nodilittorina mespillum (Mühlfeld, 1824) (19,9 %) (Table 2).

Table 2. Dominant species of molluscs from the rocky shore of Gibara.

Class

Species

Frequency (%)

Number of individuals

POLYPLACOPHORA Chiton squamosus

0,39

8

GASTROPODA Echinolittorina ziczac

26,7

546

Tectarius antoni

25

511

Nodilittorina mespillum

19,9

406

Cenchritis muricatus

6,13

125

BIVALVIA Hormomya exustus

3,33

68

The station 2 had the higher species richness (S = 22), whereas the lower value were registered at station 1 (S = 9). In the supralittoral zone were registered the higher species richness (S = 16) (Table 2).

Table 3. Checklist and presence (0) – absence (1) matrix per sampling station of the molluscs found in the rocky shore of Gibara. ML: Intertidal, SL: Supralittoral. *New record for the zone.

SPECIES

Stations

E1

E2

E3

ML

SL

ML

SL

ML

SL

Phyllum  MOLLUSCA
Class POLYPLACOPHORA
Order NEOLORICATA
Family Chitonidae
Genus Chiton Linné, 1758
1.Chiton marmoratus Gmelin, 1791*

0

0

1

0

1

0

2. Chiton squamosus Linné, 1764*

1

0

1

0

1

0

Genus Acanthopleura Guilding, 1829
3. Acanthopleura granulata (Gmelin,1791)*

0

0

1

0

1

0

Class GASTROPODA
Order VETIGASTROPODA
Family Fissurellidae
Genus Fissurella Bruguière, 1788
4. Fissurella barbadensis (Gmelin, 1791)

1

0

1

0

1

0

5. Fissurella nodosa (Born, 1778)

0

0

1

0

1

0

Order NERITOPSINA
Family Neritidae
Genus Nerita Linné, 1758
6. Nerita peloronta Linné, 1758

0

1

0

1

0

1

7. Nerita tessellata Gmelin, 1791*

0

1

0

1

0

1

8. Nerita versicolor Gmelin, 1791

0

0

1

1

0

1

Genus Puperita Gray, 1857
9. Puperita pupa (Linné, 1758)

0

0

0

1

0

1

Genus Neritina Lamarck, 1816
10. Neritina meleagris Lamarck, 1822*

0

0

0

0

0

1

Orden SORBEOCONCHA
Family Planaxidae
Genus Supplanaxis Thiele, 1929
11. Supplanaxis nucleus (Bruguière, 1789)*

0

1

1

0

0

0

Family Littorinidae
Genus Echinolittorina Habe, 1856
12. Echinolittorina meleagris (Potiez y Michaud, 1838)*

0

0

1

0

0

1

13. Echinolittorina ziczac (Gmelin, 1791)

0

0

0

1

0

1

Genus Nodilittorina Martens, 1897
14. Nodilittorina mespillum (Mühlfeld, 1824)*

0

0

0

1

0

1

Genus Tectarius Valenciennes, 1832
15. Tectarius antoni (Philippi, 1846)

0

0

0

1

0

1

Genus Cenchritis Von Martens, 1900
16. Cenchritis muricatus (Linné, 1758)

0

0

0

1

0

1

Family Vermetidae
Genus Petaloconchus H. C. Lea, 1843
17. Petaloconchus erectus (Dall, 1889)*

0

1

0

1

0

1

Family Costellariidae
Genus Vexillum Röding, 1798
18. Vexillum gemmatum (Sowerby, 1871)*

0

0

1

0

0

0

Family Muricidae
Genus Plicopurpura Cossmann, 1903
19. Plicopurpura patula (Linné, 1758)

0

0

1

0

1

0

Family Columbellidae
Genus Nitidella Swainson, 1846
20. Nitidella nitida (Lamarck, 1822)*

0

0

1

0

0

0

Clase BIVALVIA
Orden ARCOIDA
Family Arcidae
Genus Arcopsis von Koenen, 1885
21. Arcopsis adamsi (Dall, 1886)*

1

0

1

0

0

0

Order MYTILOIDA
Family Mytilidae
Genus Hormomya Mörch, 1853
22. Hormomya exustus (Linné, 1758)

0

0

1

0

1

0

Order PTERIOIDA
Family Pteriidae
Genus Pinctata Röding, 1798
23. Pinctata imbricata Röding, 1798*

0

1

0

0

0

1

FamilyIsognomonidae
Genus Isognomon Lightfoot, 1786
24. Isognomon radiatus (Anton, 1839)*

0

1

0

0

0

0

Species richness (S)

3

6

13

9

7

12

Community structure and zonation

In the intertidal zone the most abundant species was the bivalve Hormomya exustus (Linné, 1758). In this zone, differences in abundance among stations were observed. At station 3 the abundance ranked for 30 ind./m2, while stations 1 and 2 had lower abundance (0,5 ind./m2 and 1,5 ind./m2, respectively) (Fig 2).

Fig. 2. Density variation of molluscs (mean ± SD) among stations y and zones.

At the supralittoral zone the epifaunals gastropods E. ziczac (Gmelin, 1791), T. antoni, N. mespillum and C. muricatus dominated in abundance. At station 1 the species N. tessellata and N. peloronta dominated in number, whereas N. mespillum, T. antoni, C. muricatus, N. versicolor, E. ziczac and N. tessellata were the most abundant at E2. At station 3 E. ziczac, T. antoni, N. mespillum and N. tessellata had the higher abundance. At E3 the abundance was 57 ind./ m2 and at E2 was 43 ind./m2, lower values were recorded at E1 (3,6 ind./m2)(Fig. 2).

Sheltered transects had the lower average abundance at the intertidal (1 ind./m2) and at the supralittoral (9 ind./m2) zones. Exposed transects had the higher values of average abundance with 16 ind./m2 in the intertidal zone and 67 ind./m2 in the supralittoral zone, contrary the lower values in sheltered zones are well evidenced (Fig. 3).

Fig.3. Density variation of molluscs (mean ± SD) among zones with different wave exposition level.

Analysis of similarities showed a clear association among stations and biotopes. The cluster analysis based on the stations and zones allowed to recognise two groups at a level of 30% of similarity. The first group comprised the supralittoral zone while the second clustered the intertidal zone. Inside of each group are clearly segregated two subgroups composed for the sheltered and the exposed transects (Fig. 4).

The cluster analysis based on the species determined two main groups at a level of 25% of similarity. The first group is composed by species that inhabits in the supralittoral zone and the second composed by species living in the intertidal zone. The species N. versicolor and E. meleagris that clustered in the first group and S. nucleus that clustered in the second one are to be found indistinctively in the intertidal and the supralittoral zones (Fig. 5).

 

 

 

 

 

 

 

 

 

 

 

 

Fig. 4. Cluster analyses based on sampling stations and biotopes, using the Bray–Curtis similarity index. Biotopes are represented by s = supralittoral, m = intertidal and Stations are E1, E2 and E3.

 

 

 

 

 

 Fig. 5 Article

 

 

 

 

 

 

 

Fig.5. Cluster analyses based on species, using the Bray–Curtis similarity index. Species are numbered as in Table 3.

 

DISCUSSION

In comparison with the work of Torres (1987) for Gibara we found only 10 species in common. Now with the present study, the checklist is enlarged with 14 new records for this coastal zone. The number of species found in the rocky shore of Gibara was lower than previous records for other coastal zones of Cuba (Ortiz, 1976; Herrera et al., 1987).

Table 3 shows that species present different distribution according their natural history, defining a zonation pattern evidenced in the cluster analysis. The species N. Versicolor, E. meleagris and S. nucleus were recorded in the intertidal and supralittoral zone having a wider range of distribution across the shore maybe related with short migrations looking for food and refuge. The numerically dominant species in the intertidal zone, the bivalve H. exustus, is a sessile filter feeder organism very common in this zone and is adapted to resist strong waves.

The dominance of E. ziczac, T. antoni, N. mespillum and C. muricatus in the supralittoral zone was reported by Ortiz (1976) and Herrera et al. (1987) that pointed out that this species are able to resist the dynamic of waves. Factors associated to that finding could be related with their capacity to move faster than other species, what allows them to find desired microhabitats, or their well developed fixation organs that keep them attached to the substrate. The spatial distribution of the molluscs in the rocky shore of Gibara follows the same zonation scheme that other rocky shores around the world where the supralittoral zone is dominated by neritid and littorinid gastropods (Lewis, 1964; Underwood & Chapman, 1998; Lee et al., 2009) and mussels dominates the intertidal zone (Committo et al., 2006).

Species richness and abundance were higher at exposed sites. The degree of wave exposure is a crucial predictor of community structure and processes (Menge and Sutherland, 1987). Olavarria et al. (2001) analyzed the distribution patterns of trophic groups of molluscs at Mazatlán bay (Eastern Tropical Pacific) and they found higher abundance in sites exposed to wave action. It is possible that variations in species richness and abundance among sampling stations in the rocky shore of Gibara could be controlled by the physical environment.

The exposed areas have more available microhabitats such as holes, cracks, crevices and rock pools modelled by wave action. It is know that the features of substrate in an important factor controlling the across and along shore distribution of organisms (Litter el al., 1983). Other factors such as food availability and predation must not be discarded, mostly in the intertidal zone. Garrity & Levings (1981) and Levings & Garrity (1983) found that predation by fish during high tides can exert controlling effects on intertidal communities.

In despite that the effects of the waves on the rocky shores communities of organisms have been investigated, this is the first time that the community structure of molluscs is compared between sheltered and exposed zones in Cuba’s sea shelf. The present study has limitations on spatial and temporal scales because the unbalance sampling effort between sheltered and exposed sites and due to snapshot observations. Nevertheless it represents the first attempt in trying to explain factors acting over the rocky shore community of molluscs in Cuba and provide a quantitative assessment of a habitat that is still very few studied in relation to other coastal ecosystems such as coral reefs, sea grasses beds, coastal lagoons and mangrove forests. These findings illustrates that it is necessary to consider differences in along and across shore features when planning base line and long-term studies of structure and composition of the living organisms in the rocky shores.

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ACKNOWLEDGEMENTS

This work was carried out in the frame of the research project “Evaluación ecológica de la zona intermareal como base para la gestión del litoral de la provincia Holguín. Sector costero Caletones-Guardalavaca” financed by Programa Territorial de Ciencia y Técnica of the Ministry of Science Technology and Environment (CITMA).