Background:

The Thalassia testudinum grasslands constitute a productive and biodiverse ecosystem, especially in the Caribbean region, where studies are focused on evaluating organisms of commercial interest.

Objective:

Identify the macrobenthic fauna associated with T. testudinum grasslands and describe the spatio-temporal changes in relation to the physical-biological parameters and granulometric characteristics of the sediment.

Materials and methods:

The samplings were carried out bimonthly (January-November 2017), on the Chacopata-Bocaripo lagoon coastal axis. Records of temperature, salinity, chlorophyll a and total seston were taken, as well as the granulometric characteristics and levels of organic matter in the sediment. The collected organisms were identified, quantified and weighed.

Results:

The environmental parameters did not show spatio-temporal variations. In the sediment, fine, very fine and silty sands predominated, without spatial variability and with temporal changes from May to November. Organic matter was greater than 7%, with a tendency to increase over time and the same behavior in all seasons. 2 412 organisms were collected: distributed in six Phyla, 56 families and 105 species. Mollusks were the dominant group, with the gastropods Engoniophus unicinctus and Bulla striata being the most constant. The community structure of the evaluated prairie showed temporal differences, without changes between the sampling stations.

Discussion:

The differences in the community structure were related to changes in the percentages of fine, very fine and silty sand, chlorophyll a levels and organic matter.

Conclusions:

The hydrodynamic processes and the flow of nutrients produced in the Chacopata-Bocaripo lagoon complex would be modulating the spatio-temporal variations of the macrobenthic fauna associated with T. testudinum, directly influencing the physical-biological and granulometric characteristics of the studied area.