Morrocoy National Park Research Articles

Anthropogenic influences on heavy metals across marine habitats in the western coast of Venezuela

Concentrations of ten metals were measured in waters and sediments at 14 sites during four sampling periods (1996–1997). These sites include various marine ecosystems that are highly influenced by industry, tourism and river discharges, nine of which are within the Morrocoy National Park. Spatially, metal concentrations in water were homogenous, whereas in sediments their distributions were related to grain size. Maximum concentrations of cadmium (Cd) and mean concentrations of copper (Cu), nickel (Ni), lead (Pb) and zinc (Zn) in water were above the guideline values proposed by NOAA, indicating the potential of these metals for producing chronic effects in marine biota. Sheltered sites showed the highest metal concentrations in sediments; with Cd and Zn above these guidelines. Enrichment factors and geo-accumulation indexes suggested that metals in sediments were largely of natural origin except for Pb, Cd and vanadium (V), which were apparently associated with industrial effluents. A disruption of the spatial distribution of metals after heavy rainfall, when exposed sites reached concentrations as high as those in sheltered sites, showed the influence of nearby rivers. The potential increase of such climatic events could represent additional stress for natural protected areas in the Caribbean.

Tasa de depredación de Coralliophila abbreviata (Neogastropoda: Coralliophilidae) sobre algunas especies coralinas del Parque Nacional Morrocoy, Venezuela

Predation rate of Coralliophila abbreviata (Neogastropoda: Coralliophilidae) on some coral species at Parque Nacional Morrocoy, Venezuela. Coralliophila abbreviata is a tropical gastropod of the Caribbean Sea. This gastropod is an important corallivore. The objective of this work was to estimate the predation rate of C. abbreviata on some coral species in the coral reefs of Morrocoy National Park, Venezuela. The localities were Cayo Sombrero and Cayo Peraza. We evaluated the rate on five coral species: Montastraea annularis, Colpophyllia natans, Diploria strigosa, Diploria labyrinthiformis and Agaricia agaricites. We used three experimentals treatments. in treatment 1 we marked colonies with buoys that had been predated by C. abbreviata. in treatments ii and iii we used exclusion cages. Treatment ii included the colony with its predators and treatment iii was the control (only the colony). The injuries of the colonies were measured every 4 days for at least a month. The predation rate in treatment i varied depending on the coral species. The highest rate was on C. natans (3.70 cm2/ind/day), while D. strigosa, D. labyrinthiformis and M. annularis did not register any predation rate (0 cm2/ind/day). in treatment ii we only detected predation activity in 1 colony of M. annularis with 0.15 cm2/ind/day. The main effect generated by C. abbreviata on the Morrocoy National Parks coral reefs could be a decrease in the coloniesreproduction and growth rate due to energetic use in tissue regeneration of injuries. Rev. Biol. Trop. 56 (Suppl. 1): 235-246. Epub 2008 May 30.

Effects of heavy rainfall on Thalassia testudinum beds

In December 1999 heavy continuous rains that lasted one week affected the Venezuelan coastline. At Morrocoy National Park, a large marine reserve, rainfall values surpassed previous 32-year records and led to a decrease of salinity to 3 psu, which lasted for over a month at some locations. This study examined effects of these changes on the shallow-water meadows of the seagrass Thalassia testudinum Banks ex Köning (1805), by comparing their structure before and after this disturbance at four selected sites. The rain acted as a pulse-type disturbance, altering the physicochemical features at all sites, which soon returned to the previously prevailing conditions. However, T. testudinum beds showed a sudden stress reaction followed by slow recovery. The disturbance prompted an increase in the amount of dead tissue and defoliation. Later a sustained increase of leaf biomass, productivity and reproductive shoots was observed, neither ever noticed before in the Park. The seagrass meadows in Morrocoy showed signs of stress even one year after the impact, suggesting that the 1999 disturbance deeply affected the characteristics of these systems within the Park.

Variabilidad temporal de la abundancia de Coralliophila abbreviata y Coralliophila caribaea (Mollusca, Coralliophilidae) en un arrecife coralino del Parque Nacional Morrocoy, Venezuela

The mollusks Coralliophila abbreviata and C. caribaea are coral predators in the Caribbean Sea . We evaluated the temporal variability of abundance and size structure of C. abbreviata and C. caribaea in Cayo Sombrero, Morrocoy National Park, Venezuelar (September 2004 - August 2005). The density of C. abbreviata and C. caribaea was evaluated monthly by means of two 50-meter long transects paralell to the coast line, at 3 m and 6 m deep; aditionally, 30 individuals of C. abbreviata were collected to measure size. The densities of C. abbreviata at the shallow transect fluctuated between 1.78 ind/m2 in September and 6.26 ind/m2 in May. The densities at the deep transect fluctuated between 4.23 ind/m2 in January and 7.66 ind/m2 in May. The densities of C. caribaea at the shallow transect fluctuated between 0 Ind/m2 (except in September) and 0.03 Ind/m2 (September) and the densities at the deep transect fluctuated between 0 Ind/m2 (October to March and July) and 0.1 Ind/m2 (April). Most individuals of C. abbreviata and C. caribaea measured between 12 and 16 mm and between 10 and 15 mm long respectively.

Effects of heavy rainfall on polychaetes: Differential spatial patterns generated by a large-scale disturbance

Heavy rainfall caused a severe disturbance on the Thalassia testudinum meadows at Morrocoy National Park in December 1999, affecting its associated infauna and inducing responses to stress in opportunistic polychaetes belonging to the Spionidae Family. The changes were evaluated at four seagrass beds, examining the structure and species composition of the Spionid macrofauna over eight samplings: four prior and four after the disturbance. Immediately after the heavy rainfall the Spionids showed transient changes, expressed as large increases of species density and richness, reaching values of 875 individuals m − 2 (against the usual 20 individuals m − 2 ) and 7 species (against the previous 1–3 species) during February 2000. These abundance pulses were represented by selected species at each location. Opportunistic species, having limited dispersion ( Streblospio gynobranchiata and polydorids) were commonly found in continentally-influenced locations whereas species having dispersal mechanisms were commonly found in stations under oceanic influence (species of the Genus Prionospio). Likewise, the observed recovery patterns indicate different rhythms: while the oceanic communities showed a fast recovery, the continentally ones returned to their original states slowly. Hence, the patterns observed in the benthic polychaete communities associated with the T. testudinum beds from Morrocoy N.P. clearly indicate that the recolonization processes, succession dynamics and recovery time depend on the spatial scale of disturbance, the life history of species involved and the particular conditions of the habitat.

Las enfermedades en corales escleractinidos: ¿un nuevo problema en el arrecife de Cayo Sombrero, Parque Nacional Morrocoy, Venezuela?

At the beginning of 1996 coral reefs in Morrocoy National Park, Venezuela, suffered an unprecedented mass mortality event. As a consequence, live coral cover dropped to 2-10%. One of the few reefs that kept live coral cover over 35% was Cayo Sombrero; nonetheless, the presence of some coral diseases has been detected within the past 2 years, representing a new source of coral mortality. Due to this situation, this study started a monitoring pro- gram on the incidence of coral diseases and syndromes in the reef of Cayo Sombrero. The CARICOMP protocol was used in order to evaluate reef health. Ten parallel band-transects (20 x 2m) where established at two depth intervals: Five between 3-8 m and five between 8-12 m, and the frequency of both, healthy and unhealthy colonies of each coral species was recorded along each band transect. In addition to other sources of coral damage (predation, silta- tion, etc), significant differences in disease incidence between the two depths intervals were tested with a Kruskall- Wallis test. The main problems observed were coral diseases such as yellow band (4,2%), dark spots (1.61%) and white plague-II (1.4%), mainly affecting Montastraea faveolata, M. annularis and Siderastrea siderea. Siltation, af- fecting massive colonies, such as Colpophyllia natans and Diploria strigosa; algae overgrowth, predation, anchor damage, and bleaching. Significant differences were found in the incidence of unhealthy (Kruskall-Wallis, p<0.05) bleached (Kruskall-Wallis, p < 0.05) and colonies affected by siltation (Kruskall-Wallis, p<0.05). More than 60% of the 585 coral colonies surveyed at both depths were found to be healthy, indicating that the Cayo Sombrero reef is still in good conditions compared to other localities in the Park. This study stresses the need to conduct early moni- toring programs that survey coral disease incidence as a source of mortality for this coral reef.

Size and reproductive status of fished spotted spiny lobster,Panulirus guttatus, in Morrocoy National Park, Venezuela: a preliminary report

The Venezuelan lobster-management plan is based on information collected from the Panulirus argus fishery in Los Roques Archipelago National Park. Panulirus guttatus are harvested illegally, as this species does not reach the minimum landing size (120 mm carapace length; CL). Fishers consider enforcement of a 120 mm minimum CL unjust and request a new regulation. The purpose of this study was to determine the basic population characteristics of P. guttatus at the Morrocoy National Park, to provide information for managers, and to establish a population monitoring program. Interviews with fishers were conducted from September to December 1999, and their catch was counted, measured, and sexed. Of the 163 lobsters surveyed, 93.3% wereP. guttatus, 6.1% P. argus, and 0.6% P. laevicauda. The size range for P. guttatus was 42.1 to 75.6 mm CL (average: 60.9 6.9 mm CL). Sex ratio favoured males (1.45:1), and 48.4% of the 62 females examined bore eggs. The smallest reproductive female measured 42.1 mm CL; the largest measured 67.7 mm CL. Fishing is carried out in shallow waters of the outer reefs; lobsters are harvested by hand during nocturnal skin diving.

Metal levels in eviscerated tissue of shallow-water deposit-feeding holothurians

Concentrations of six metals (Al, Cu, Mn, Ni, Pb, Zn) were determined in eviscerated digestive tract tissues of the sedimentivorous holothurians Holothuria mexicana and Isostichopus badionotus from 28 stations in the Morrocoy National Park (MNP), Venezuela. Eviscerated tissues of large individuals of both species (contracted length ≥20 and 15 cm, respectively) exhibited significantly higher metal concentrations than small individuals at the two biotopes under study. In comparison with the adjoining sediments, the holothurians enriched Cu, Ni, Pb and Zn. Concentrations of metals in small specimens (CL ≤10 cm) of I. badionotus tissues were higher than in H. mexicana (CL ≤15). Mean concentrations of Cu, Pb and Ni in H. mexicana and I. badionotus tissues were higher than reported values for other resident marine invertebrates in the MNP, as well as deep-sea holothurians, and also exceeded legal reference and maximum recommended values. This study hints that holothurians, which in this project have shown their potential as biomonitors, may provide a pathway to several metals for transfer from mangrove sediments. These metals might pose ex situ public health risks, since a sporadic furtive fishery of holothurians is currently under way in the study area for export to Far East markets.

Fase gametofítica del helécho Llavea cordifolia (Pteridaceae)

Morrocoy National Park used 19 be considered the most important continental coral reef of Venezuela However, in January of 1996, there was a massive mortality of the bentbic organisms for unknown reasons. The coral reef community was monitored since 1995, the year before the event, and yearly after that, until June 1999, by sampling linear transects and quadrats. A total of 26 hard corals were recorded in the study site (Playa Mero) in 1995 (36.56% cover), which already had some deterioration because 90.86% of the living coral cover was rep­ resented basically by four species, M annularis with 51.36%, Colpophyllia natans with 18.22%, Agaricia agaricites with 11.58% and Porites porites with 9.70%. Three months after the event, living coral cover was only 4.84% and a1gae, particularly Dyctiota spp. covered most of the surface (81.89%). Benthic organisms suffered massive mortality over the whole depth gradient and in most park reefs. Even after three years the reef commu­nity shows highly perturbed conditions, with 85% of the total cover represented by the categories: dead coral, dead coral overgrowth by algae and sand. From the initial coral rishness of the area (26 species) only nine species were observed although in very lowcover (<1%), except for M. annularis and M. franksi, which presented light­ly higher percentages.

Pectiniunguis bollmani n.sp., from the Coralline Island Cayo Sombrero (Venezuela) with Notes on P. halirrhytus Crabill, 1959 (Chilopoda: Geophilomorpha: Schendylidae)

Pectiniunguis bollmani n. sp. (Chilopoda: Geophilomorpha: Schendylidae) is described from the Morrocoy National Park (State of Falc¢n, Venezuela) and considered as very closely related to P. halirrhytus Crabill, 1959. Additional data on P. halirrhytus Crabill and comments on the geographical distribution of the two taxa, both probably halophilous, are also given.

Baseline study on the levels of organic pollutants and heavy metals in bivalves from the Morrocoy National Park, Venezuela

Baseline study on the levels of organic pollutants and heavy metals in bivalves from the Morrocoy National Park, Venezuela

Relación simbiótica entre Entocladia endozoica (Ulvales) y Plexaura flexuosa (Gorgonacea: Plexauriidae)

This study, done at Morrocoy National Park, Venezuela, describes and analyzes tumor-like growths resul­ting from the invasion of Plexaura flexuosa axial skeleton and surrounding tissues by filaments of the chlorophycean Entocladia endozoica. A stratified random sampling was done in three transects of 72 m2 each at 4,8 and 12 m depth. At each depth, all tumors present in nine randomly chosen colonies of P. flexuosa were cut and preserved and five tu­mors ere collected in each of the remaining colonies on the transect. The external and internal morphology of the tu­mors and the spatial relationship of the algal filaments with the axial rod of the octocoral was studied through stan­dard microscopy and scanning electron microscopy. Transmission electron microscopy was used for taxonomic pur­poses and to identify the reproductive stage of the filaments. In addition, optical fiber sensors were used to detect the light path of laser beam projected from a discharge lamp through the coenenchymal material of the tumor, in order to find out if ambient light can reach the algal filaments. Results showed that the E. endozoica filaments in a tumor of P. Flexuosa were found on the tips of axis projections of variable size that were perpendicular to the main rod. The­se projections often penetrate the axial sheath towards the coenenchyma and could contact the ambient water through fractures of the external wall of the tumor. Reproductive filaments were only found on axis projections that had grown enough to penetrate the axial sheath and the coenenchyma. Filaments on the main axial rod or on small projections were in the vegetative stage. The laser study indicated that the light could at least reach the coenenchymal material where the reproductive filaments are found. We postulate a mechanism through which the oetocoral tries to get rid of the algal filaments by pushing them out by the development of projections, thus causing vegetative filaments to be­ come reproductive. Light may also contribute to this transformation.

Benthic communities associated to &lt;i&gt; Thalassia testinum&lt;/i&gt; (Hydrocharitaceae) at three localities of Morrocoy National Park, Venezuela

Se analizó la comunidad bentónica asociada a TIJOlassia testudinum y su relación con algunos parámetros bióticos y abióticos, en tres localidades del Parque Nacional MOlTocoy, Falcón-Venezuela; éstas fueron seleccionadas de acuerdo al grado de exposición al mar abierto: A(protegída), B (intermedia) y C (expuesta). En cada localidad se demarcó un área de 20 x 20m, se muestrearon aleatoriamente 10cuadrantesfmes, (130 cuadrantesflocalidad). Se efectuaron registros de oxígeno disuelto, salinidad, temperatura, porcentajes de materia orgánica, carbono y nitrógeno, textura del sedimento, biomasa foJiar y de rizoma de T. testudinum. Todos los parámetros analizados presentaron un gradiente escalonado. Materia Orgánica, Carbono y Nitrógeno, Oxígeno disuelto, Salinidad y Temperatura presentaron el gradiente: A&gt;B&gt;C, Los porcentages de Arena, Limo y Arcilla presentaron un gradiente inverso. El patrón en la Diversidad, Equidad y Dominancia fue: B&gt;C&gt;A. La fauna colectada estuvo compuesta por los grupos: Coelenterata (Anthozoa), Polichaeta, Sipuncula, Mnlusca, Crustacea y Echinodermata. Se identificaron 15 especies de moluscos (gastrópodos y bivalvos), (3 % de los invertebrados colectados).