Bioremediation Capabilities of Hymeniacidon perlevis (Porifera, Demospongiae) in a Land-Based Experimental Fish Farm

Abstract

The expansion of aquaculture practices in coastal areas can alter the balance of microbial communities in nearby marine ecosystems with negative impacts on both farmed and natural species, as well as on human health through their consumption. Among marine filter-feeder invertebrates, poriferans are known as effective microbial bioremediators, even though they are currently still underutilized in association with fish mariculture plants. In this study, we investigate the microbial bioremediation capability of the demosponge Hymeniacidon perlevis in an experimental land-based fish farm where this species occurred consistently in the drainage conduit of the wastewater. Microbiological analyses of cultivable vibrios, total culturable bacteria (37 °C), fecal and total coliforms, and fecal enterococci were carried out on the fish farm wastewater in two sampling periods: autumn and spring. The results showed that H. perlevis is able to filter and remove all the considered bacterial groups from the wastewater, including human potential pathogens, in both sampling periods. This finding sustains the hypothesis of H. perlevis use as a bioremediator in land-based aquaculture plants as well.

Life-cycle traits in the demosponge Hymeniacidon perlevis in a land-based fish farm

“…Compared to other groups, specimens in the frames closest to the wastewater inlet (group III) were subjected to a higher microbial concentration ( Longo et al, 2022 ), thus having a greater quantity of easily filterable food. It is reasonable to hypothesize that the furthest frames (group I) received wastewater partially filtered by sponges in the previous frames (group III and II) with a lower microbial concentration.…”

“…The considered drainage conduit consists of a cement canal 4.0 m long, 0.57 m wide, and 0.15 m deep. It is closed by walkable inspection protection, making this part of the conduit completely dark ( Longo et al, 2022 ) ( Fig. 1 ).…”

“…1 ). As described by Longo et al (2022) , the water used in this land-based fish farm is sea-groundwater with the temperature, salinity and pH almost constant throughout the year (18 ± 0.5 °C, 34 ± 1‰, 7.09 ± 0.029) ( Carbonara et al, 2020 ; Carbonara et al, 2021 ). Indeed, in coastal areas, there can be aquifers of marine origin; if sea water percolating into an aquifer passes through limestone, as in this case, the water circulating into the fish farm is a marine nutrient-free groundwater, without macroscopic organisms of the benthos ( Awal, McDowall & Christie, 2016 ; Allan et al, 2009 ).…”

“… Schematic drawing (not in scale) and real picture of the wastewater drainage conduit where the sponge Hymeniacidon perlevis lives (modified from Longo et al, 2022 ) with polyvinyl chloride (PVC) frames utilized for sponge volume measurement. In the red boxes picts of H. perlevis within a PVC frame and a specimen collected for analysis.…”

“…This unusual discovery offered the opportunity to investigate the reproductive cycle and growth performance of H. perlevis over an entire year, correlate biological traits with the main physicochemical parameters, and evaluate the impacts of these drivers on H. perlevis life-cycle phases in a land-based fish farm. Moreover, the present study sought to improve existing knowledge about the effective environmental conditions for H. perlevis maintenance in land-based fish farms, which is especially important given the recent interest in the use of this sponge as a bioremediator of microbial load, including those potentially pathogenic ( Fu et al, 2006 ; Longo et al, 2010 ; Longo et al, 2016 ; Longo et al, 2022 ; Zhang et al, 2010 ).…”