Temporal and small‐scale spatial variations in abundance and biomass of seagrass‐dwelling sponges in a tropical estuarine system

Abstract

Although marine sponges are one of the most ecologically important benthic groups in marine ecosystems, their ecological role in seagrass beds from estuarine environments is little known. In this study we investigated the temporal and small‐scale spatial variability in the abundance and biomass of the three common seagrass‐dwelling sponges Halichondria melanadocia, Haliclona implexiformis and Chondrilla caribensis in a tropical estuary of the Southern Gulf of Mexico. The influence of biotic (physical characteristics of the seagrass) and abiotic (temperature, salinity, water movement, sediment particle size and sedimentation rate) variables on the spatio‐temporal variability of these population descriptors was evaluated. In addition, a complete identification of the sponge species through morphology and COI mtDNA sequences (integrative taxonomy) was performed. Chondrilla caribensis and H. melanadocia had the highest overall average abundance and biomass, respectively. There was no significant correlation with temperature and salinity. In H. melanadocia, temporal variations in its average biomass were positively related to changes in the average size of individuals, whereas in H. implexiformis and C. caribensis these intra‐annual variations in biomass were positively related to changes in their average abundance. Important declines in the average biomass and size of H. melanadocia and in the average abundance of H. implexiformis occurred during the transition period from the dry to the rainy season, which was attributed to fragmentation and shrinkage processes. Moreover, the abundance and biomass of the three sponge species showed high small‐scale spatial variations within the seagrass meadow, but without a clear pattern of variation related with the distance from the shore. In H. implexiformis a significant negative relationship was found between its average biomass and the seagrass biomass. In H. melanadocia and H. implexiformis as well, their abundance was positively related with the proportion of coarse particles of the sediment (mollusk shell debris). Multivariate analyses confirmed that the proportion of coarse particles in the sediment, either acting alone or in conjunction with other variables such as seagrass shoot density and sedimentation/resuspension rate, was the variable that best explained the distribution of sponges within the seagrass meadow. This is one of the few studies on the population dynamics of sponges in seagrass meadows from estuarine environments.

Trophic Models of Seagrass Ecosystems in Maqueda Channel, Caramoan Peninsula, Philippines

“…Experiments showed that a large quantity of aboveground biomass of seagrass are consumed by grazers [13] yet most food webs of seagrass systems depicted that only a small amount of seagrass material are assimilated [14]. This could be explained by the high rate of excretion but low rate of assimilation of consumed seagrass material [15] as well as the temporal and spatial variability in the abundance and biomass of the seagrass-dwelling organisms [16].…”

Mind your neighbourhood: Biotic and abiotic factors shaping the small‐scale spatial distribution of sponges (Demospongiae) in tropical urban beaches

“…There are other important variables that could be influencing in the spatial distribution of the sponges, being directly or indirectly related to the presence of other organisms, generating predation pressure or competition for space (Abdo, ; Cárdenas & Montiel, ; Núñez Flores et al, ). The substrate covered by algae is one of the factors considered to be very important for structuring a marine benthic community (Ávila et al, ). The “green algae” group was recovered as one of the significant modulators of C. caelum , and the “turf” group was recovered as one of the variables explaining the density of T. ignis .…”

“…The structure of Demosponge assemblages has been well studied quantitatively by relating the influence of primarily physical factors (such as substrate inclination and depth) to the spatial distribution of these organisms (Ávila, Ávila‐García, & Cruz‐Barraza, ; Barthel & Tendal, ; Bell & Barnes, ; Bell & Smith, ; Cárdenas & Montiel, ; Freeman & Easson, ; Monteiro & Muricy, ; Moraes et al, ; Muricy, ; Núñez Flores et al, ; Oigman‐Pszczol, Figueiredo, & Creed, ; Ruiz & Zea, ). However, the majority of these works were carried out at the assemblage level (i.e., not focused on a single species or group of species) and in areas away from direct anthropic impacts as observed along the coastline of areas with high levels of urbanisation.…”

“…However, it is worth noting that some works have compared the structure and composition of the sponges in different habitats (Bell & Carballo, ; Benedetti‐Cecchi et al, ; Cárdenas et al, ). Furthermore, a few studies have also investigated the relationship between the abundance of sponges and other organisms present in benthos (Ávila et al, ; Ávila, Riosmena‐Rodríguez, & Hinojosa‐Arango, ; Benedetti‐Cecchi et al, ; Cárdenas et al, ; Preciado & Maldonado, ).…”

Macrofaunal assemblages associated with two common seagrass‐dwelling demosponges (Amorphinopsis atlantica and Haliclona implexiformis) in a tropical estuarine system of the southern Gulf of Mexico

“…In the Mexican coasts of the Gulf of Mexico (Tropical Western Atlantic) there are extensive seagrass meadows [15], in which the biodiversity of associated invertebrates has still been poorly investigated [16,17]. Particularly, within the estuarine system of Laguna de Terminos, located west of the Yucatan peninsula, there are shallow seagrass meadows (Thalassia testudinum, Syringodium filiforme and Halodule wrigtii) whose permanence has been threatened by both, natural (e.g.…”