Variation in species diversity and functional traits of sponge communities near human populations in Bocas del Toro, Panama

Abstract

Recent studies have renewed interest in sponge ecology by emphasizing the functional importance of sponges in a broad array of ecosystem services. Many critically important habitats occupied by sponges face chronic stressors that might lead to alterations in their diversity, relatedness, and functional attributes. We addressed whether proximity to human activity might be a significant factor in structuring sponge community composition, as well as potential functional roles, by monitoring sponge diversity and abundance at two structurally similar sites that vary in distance to areas of high coastal development in Bocas Del Toro, Panama. We surveyed sponge communities at each site using belt transects and differences between two sites were compared using the following variables: (1) sponge species richness, Shannon diversity, and inverse Simpson’s diversity; (2) phylogenetic diversity; (3) taxonomic and phylogenetic beta diversity; (4) trait diversity and dissimilarity; and (5) phylogenetic and trait patterns in community structure. We observed significantly higher sponge diversity at Punta Caracol, the site most distant from human development (∼5 km). Although phylogenetic diversity was lower at Saigon Bay, the site adjacent to a large village including many houses, businesses, and an airport, the sites did not exhibit significantly different patterns of phylogenetic relatedness in species composition. However, each site had a distinct taxonomic and phylogenetic composition (beta diversity). In addition, the sponge community at Saigon included a higher relative abundance of sponges with high microbial abundance and high chlorophyll a concentration, whereas the community at Punta Caracol had a more even distribution of these traits, yielding a significant difference in functional trait diversity between sites. These results suggest that lower diversity and potentially altered community function might be associated with proximity to human populations. This study highlights the importance of evaluating functional traits and phylogenetic diversity in addition to common diversity metrics when assessing potential environmental impacts on benthic communities.

Sponges and Their Microbiomes Show Similar Community Metrics Across Impacted and Well-Preserved Reefs

“…in the perturbed zones. Similar decrease in species richness (S) and Shannon diversity index (H′) due to anthropogenic impacts has been previously reported for the coral communities in the study area (Tkachenko et al, 2016) and for sponge diversity in different oceans (Powell et al, 2014; Easson et al, 2015). Indeed, low diversity but high abundance with dominance of a few species is a common feature of many polluted habitats (Piola and Johnston, 2008; Powell et al, 2014).…”

“…Sponges usually show a high species diversity in well-preserved ecosystems (Van Soest et al, 2012), which has been suggested to decrease under anthropogenic pressures (Easson et al, 2015). Shifts in nutrient cycling and ecosystem functioning, which occur in degraded reef systems (Bell et al, 2013, 2018; Easson et al, 2015), are considered to be responsible for decreases in sponge biodiversity. However, a few, likely opportunistic, sponge species have been reported to inhabit and even dominate degraded coral reefs (Maliao et al, 2008).…”

Marine dock pilings foster diverse, native cryptobenthic fish assemblages across bioregions

“…Because other factors (broadly co‐varying with latitude) may influence cryptobenthic fish assemblages (e.g., population density, shipping traffic), we insured that docks within each location were spread across a variety of sites with varying abiotic factors. For example, docks in Panama ranged from Bocas town to the relatively pristine Punta Caracol (Easson, Matterson, Freeman, Archer, & Thacker, ), while docks in Belize were spread across inshore and outer‐shelf sites of the Belizean Barrier Reef, and docks in North Carolina ranged from the City pier of Beaufort to the Shackleford Banks (Fig. ).…”

Fish, Coral, and Sponge Assemblages Associated With Altiphotic and Mesophotic Reefs Along the Guánica Biosphere Reserve Continental Shelf Edge, Southwest Puerto Rico

“…Our dataset increases the knowledge of southwest Puerto Rico's altiphotic and mesophotic fish, coral, and sponge assemblages. We highlight the need to continue monitoring this dynamic ecosystem and emphasize that it is crucial to perform long-term time series assessments of the general area to fully assess any fluctuations in community structure (i.e., abundance, dominant species shift, disease, bleaching) (Wulff, 2001(Wulff, , 2006Easson et al, 2015) and preservation of the overall marine biodiversity (Miloslavich et al, 2010;Jenkins and van Houtan, 2016;Hoeksema et al, 2017). This study demonstrates that altiphotic and mesophotic reefs across the Guánica continental shelf edge support different assemblages of corals, sponges and fish.…”