BULLETIN OF THE OCEANOGRAPHIC INSTITUTE OF VENEZUELA

BIONOMÍA BENTÓNICA COSTERA DE LA ISLA DE CUBAGUA (VENEZUELA). II. COSTA NORTE Y SUR

2026-04-14T14:20:35-04:00

The benthic bionomy of the north and south coasts of Cubagua was studied. Twenty-seven transects (100 m long) were marked every 25 m, where quadrats (0.25 m2) were placed. Samples were extracted by diving and community distribution was determined. Fish were collected with 25 m seine (5 mm mesh). Sediment was extracted from the midlittoral, 50 and 100 m from the beach. On the north coast, seven rocky beaches were studied, three sandy, two with sand and rocks, and two sandy muddy beaches. Thalassia forms isolated meadows; up to 14 species of crustaceans, 15 molluscs, and 17 fish were captured 50 m from the beach. Between La Piragua and Punta Colorada, near the coast, there is a discontinuous fringe of P. strigosa and D. labyrinthiformis corals with a diameter > 3 m. At 50-100 m, the bottom has coarse sand, abundant octocorals, and caves for Amphichthys and Opisthognathus fish. Charagato Bay has a sandy bottom down to 100 m, except for a few places with octocorals; at Punta Laja and La Tintorera, some slabs are 40 cm deep and abundant coral fish; this bay is heavily influenced by tourism and numerous constructions. On the south coast, ten rocky beaches were studied, two sandy with rocks and one sandy beach; 20 species of crustaceans and 15 species of molluscs and fish were identified. The Thalassia meadows are continuous; up to 25 m, they have long leaves (> 20 cm) and reddish coloration due to epiphytic algae; at 100 m, the leaves are short (< 15 cm), and numerous Lytechinus and Echinometra sea urchins live there. The pelecypods P. imbricata and A. zebra are abundant; their dead shells are consolidated and form a typical habitat; Pseudodiploria corals are smaller than on the north coast. On rocky beaches, the brown algae Gracilaria abounds; between La Garza and La Vaquita, >100 m from the beach, there are vast colonies of Millepora. The study identified 99 species of fish, 210 mollusks, 178 decapod crustaceans, and 24 ophiuroids. A total of 14 were new national reports

CRUSTÁCEOS DECÁPODOS BENTÓNICOS LITORALES DE LA ISLA DE LA TORTUGA. II.- SUPERFAMILIA GRAPSOIDEA MACLEAY, 1838

2026-04-21T14:50:00-04:00

Ten species of grapsoidean crabs are first time recorded from La Tortuga Island: Aratus pisonii, Armases ricordii, Cardisoma guanhumi, Cyclograpsus integer, Hartnollius lateralis, Geograpsus lividus, Grapsus grapsus, Pachygrapsus transversus, Percnon gibbesii and Plagusia depressa. This way, at least one member of each of the grapsoidean families listed for Venezuela is recorded from La Tortuga Island, and the number of decapod crabs known from this island rises to 51 species.

PRIMER REGISTRO DE Neopetrosia carbonaria Lamarck, 1814 (PORIFERA, DEMOSPONGIAE), PARA VENEZUELA

2026-04-15T14:18:29-04:00

Marine sponges are one of the most prominent functional components of the biotopes in Mochima Bay (Sucre State, Venezuela), which currently has 28 species inventoried. During an update of the sponge species in this bay, two specimens were collected in October 2024. These were detached from the substrate with a knife, placed in plastic bags, and refrigerated. Before collection, in situ photographs were taken with a digital camera, and the external characteristics of the sponge were noted. In the laboratory, the relevant histological analyses were performed to understand the sponge’s structure and determine the spicule typology. The results showed that the specimens belong to the species Neopetrosia carbonaria Lamarck, 1814. This species has an encrusting or massive form, is black, and has a uniform, smooth, or micro rugose surface with a firm consistency. The oscules are scattered, with a volcano-shaped membrane, measuring 3 to 5 mm in diameter. The skeleton consists of thick spicular bundles, forming a reticulum of rounded to polygonal meshes, 130-650 μm wide, with loose spicules. The ectosome is a regular isodictyal reticulation of simple spicules joined by spongin at their nodes, with a superimposed choanosome forming a sub-superficial plot. The spicules are hastate oxeas megascleres, robust, and slightly curved, measuring 162-200 μm in length and 1.4-2.4 μm in width. The studied specimens were found in shallow waters, on seagrass beds, dead corals or rocks. Given that N. subtriangularis (Duchassaing, 1850) was previously the only known species of the genus in the country, this represents the second record of a Neopetrosia species for Venezuela, thereby extending the geographic distribution range of N. carbonaria in the Caribbean Sea.

TENDENCIAS EVOLUTIVAS DEL DESARROLLO CORPORAL DE LOS ESPIÓNIDOS (SPIONIDAE: ANNELIDA). ¿CÓMO SE RELACIONA LA FORMA DEL CUERPO CON EL MODO DE VIDA?

2026-04-15T14:49:45-04:00

This paper presents the morphology of one of the most complex and species-rich families of polychaetes. The body development of spionids and the relationship between body shape and lifestyle are studied. The evolutionary trend of each of the morphological structures of spionids is analyzed, and several hypotheses are formulated. One of these is that branchiae without pinnae are the plesiomorphic condition, as they are found throughout the family, while branchiae with pinnae are the derived or apomorphic condition. The evolutionary trend of branchiae fusion with respect to notopodal lamellae is also analyzed, and three hypotheses are proposed.

LECITOTROFÍA EN EL DESAROLLO LARVAL DE Mesotheres strombi (Rathbun, 1905) (CRUSTACEA: BRACHYURA: PINNOTHERIDAE)

2026-05-06T08:37:51-04:00

The Pinnotheridae family in Venezuela is represented by 14 species, including Mesotheres strombi. Three ovigerous females of M. strombi were obtained from artisanal fisheries of the gastropod Strombus pugilis, with eggs in advanced embryonic stages. They were placed individually in glass containers, without any food supply, until the eggs hatched. A total of 192 larvae were distributed into 24-well ice cube trays, each well holding 2.8 ml. Two experimental groups were established: Group A (Experimental): no food provided, and Group B (Control): fed at a density of 10 to 15 Artemia nauplii. Water was changed daily in the cubicles, and molts and deaths were recorded. No significant differences were found in survival or in the duration of the different stages between the two experimental groups (ANOVA P > 0.05). The larval development of M. strombi comprises two zoea stages and one megalopa stage, with the first and second larval stages lasting 2 days each and the postlarval stage lasting 2–3 days before molting into the next stage. The larvae can reach the first crab stage using only their yolk reserves. On the seventh day of the experiment, the survival rate of the first crab reached its maximum (91.67% in Group A and 84.38% in Group B). The first crab could live in Group A until day 36 and in Group B until day 35. In both groups, no crab managed to complete the molt to the next stage.

MICROPLÁSTICOS EN LA ARENA DE UNA PLAYA URBANA DEL GOLFO DE CARIACO, VENEZUELA

2026-05-06T08:48:29-04:00

Microplastics (MPs) are small, persistent pieces of plastic (<5 mm) that accumulate in various marine ecosystems worldwide, including beaches. These particles degrade habitat quality and negatively impact aquatic organisms through ingestion at all levels of the food web. This study quantified, characterized, and determined the temporal distribution of MPs in the sand of Playa San Luis, the busiest urban beach in the Gulf of Cariaco, Venezuela. The average abundance of MPs was highest during the rainy season (14.84 MPs kg–1), followed by the transitional season (11.79 MPs kg–1) and the dry season (8.16 MPs kg–1). Fibers were the most common morphology (67 %), and among these, transparent fibers were the most abundant. MPs made of polyethylene, polypropylene, polyester, and polystyrene were identified. The high presence of fibers is attributed to wastewater effluents, fragmentation of fishing gear, and clothing shed by beachgoers. The greater abundance of MPs during the rainy season suggests an intensification of the pathways for these contaminants, coinciding with holiday periods and increased river flows. The study demonstrates the presence of MPs at San Luis Beach, highlighting the need for mitigation measures and further research to understand their consequences.

MACROFAUNA ASOCIADA A PRADERAS DE Thalassia testudinum Y Halophila stipulacea (HYDROCHARITACEAE) EN LA ENSENADA DE YAPASCUA, PARQUE NACIONAL SAN ESTEBAN, VENEZUELA

2026-05-16T08:44:07-04:00

Seagrass beds support a great abundance and diversity of benthic organisms, providing important spawning, nursery, protection and food to fish and invertebrates. This study characterized the macrofauna associated with a seagrass meadow in Ensenada de Yapascua, Parque Nacional San Esteban. Four zones were selecting within, with two perpendicular transects to the coast, with five sampling points of 1 m, 10 m, and at the end of the bed (15–20 m). Samples were taken from the mouth to the internal of the inlet during the rainy season (July-November 2015). A marked zonation of the species Thalassia testudinum and Halophila stipulacea was observed. The biomass of T. testudinum was higher in July, especially near the mouth of the inlet (Z1 and Z2) and H. stipulacea in November. A clear separation was observed between Zones 1 and 2 where T. testudinum dominated, and zones 3 and 4, where the biomass of H. stipulacea was greater. The total density of benthic organisms was 13,800 ind/m2, the most representative were: polychaetes (30%), nematodes (19%) gastropods (18%), and peracarids (14%). In July, a higher density of organisms (17,340 ind/m2) was estimated (November 11,680 ind/m2), with more than 70% dissimilarity near the mouth of the inlet compared to zone 4 (internal). These variations could be attributed to greater standing biomass and density of T. testudinum in the mouth, which represent more resource availability and physical complexity. These results highlight the effects of the presence of that invasive species H. stipulacea

VARIACIONES PLURIANUALES DE LA TEMPERATURA NOCTURNA Y SU RELACIÓN CON LA ESCASEZ DE Sardinella aurita EN EL SURESTE DE MARGARITA, VENEZUELA (2002-2018)

2026-05-21T10:46:23-04:00

Between 2002 and 2005 in the southeast of Isla Margarita, 168,204 t of sardines were caught, it was the most important fishing ground in the country. Since 2006, catches have decreased significantly. They consider that due to the increase in water temperature, the schools do not approach the coast, where they are fished with beach seine nets, which is discussed being the objective of the work. For 17 years (2002-2018) at night (6:30 to 10:00 pm), biweekly water samples (1 and 20 m) were obtained and the temperature was measured with a digital thermometer, which ranged between 21.6 and 30.5° C. In the period 2002 to 2004 were the largest captures of the resource (average 84,679 t/year) and in the water column (20 m) the annual temperature varied between 24.65 and 25.33 °C (average 25.09 °C); In 2005 the catches decreased to 44,772 t and the average temperature was 26.22 °C; In the period from 2006 to 2015, fishing was low (range 3,185 to 9,437 t) and the average temperature varied between 25.76 and 27.03 °C. In 2016 and 2017, sardine catches increased (average 46,651 t) and the highest temperatures of 27.26 and 27.54 °C were also recorded. Between 2002 and 2018, the average temperature increased < 2 °C and it is doubtful that it is the only cause of the sardine shortage in the fishing ground. It is proposed that the schools that are captured in Margarita come from the state of Sucre, where it is possible that overfishing occurs with questioned fishing gear (purse seines) and captures juveniles, affecting the recruitment, fishing and sustainability of the resource. It is suggested to study the abundance of picoplankton, as a probable cause of the sardine shortage.