Plastics in Porifera: The occurrence of potential microplastics in marine sponges and seawater from Bocas del Toro, Panamá

Abstract

Microplastics (MP) are now considered ubiquitous across global aquatic environments. The ingestion of MP by fish and other marine vertebrates is well studied, but the ingestion of MP by marine invertebrates is not. Sponges (Phylum Porifera) are particularly understudied when it comes to MP ingestion, even though they are widely distributed across benthic habitats, can process large volumes of seawater, and can retain small particles within their water filtration systems. This study examines the presence of potential MP (PMP) in wild marine sponges and seawater collected in Bocas del Toro, Panamá. Subsurface seawater and tissue from six common Caribbean sponge species was collected in Saigon Bay, a heavily impacted, shallow-water coral reef. Seawater samples were filtered onto glass fiber filters to retain any PMP present and sponge tissue was digested with bleach, heated and filtered. Filters were examined using fluorescence microscopy to quantify PMP. An average of 107 ± 25 PMP L–1 was detected in seawater from Saigon Bay with particles ranging in size between 10 μm and ~3,000 μm. The number of PMP found in sponge tissue ranged between 6 ± 4 and 169 ± 71 PMP g–1 of dry tissue. Most particles found in sponge samples were very small (10–20 μm), but fibers greater than 5,000 μm were detected. Our results indicate that PMP exists within the tissues of the sponges we studied, but future studies should confirm the presence of MP in sponges using chemical analysis. Most importantly, the discrepancy between low levels of PMP in our sponge samples and high levels in the surrounding seawater highlights the potential for sponges to resist and/or egest MP. Finally, we provide a critical evaluation of our methods to improve their use in future MP work with benthic marine organisms.

Preliminary Report of Microplastic (MPs) Presence on East Java Freshwater Sponges at Brantas Porong River

“…Food particles of marine sponges are generally <70 μm in diameter because the sponge ostia are generally 60 μm in diameter and are more likely to retain particles >50 μm from entering the sponge body. This can affect the sponge body based on species, ostia/ostium size, and body anatomy and morphology (choanocyte and exhalant/inhalant duct) [24]. Microplastic particles have the potential to clog the sponge's filtration system.…”

“…There have been many studies on the ingestion of microplastics by freshwater organisms, both vertebrates and invertebrates, with fish being the most studied group of aquatic organisms [19] and followed by other freshwater organisms, such as zooplankton (Daphnia magna) [20], arthropods (Chironomus riparius), gastropods (Physella acuta), annelids (Lumbricus variegatus) [21], crustaceans (Echinogammarus veneris) [22], diatoms (Cyclotella meneghiniana) [23], etc. However, sponges (Porifera) themselves are still very poorly studied in microplastic research [24], especially in Indonesia.…”

“…Sponges are active filter feeders, and their main sources of nutrition are prokaryotes and phytoplankton which they receive by filtering water particles containing food particles [27]. Sponges can process large amounts of seawater through aquiferous systems or canal systems as storage filters because they are lined with pinacocytes that carry water in/out of choanocyte chambers responsible for pumping water through the system [24]. The uptake of microplastics can pose a threat to sponges and have significant impacts on their lives, such as disruption of physiological functions, such as impaired opening of ostia, stunted growth, and interference with respiration in sponges [26] [24].…”

Microplastics: impacts on corals and other reef organisms

“…Porifera are widely distributed through the coral reef ecosystem and filter large volumes of water, removing a wide size range of particles. It remains unclear whether selective uptake occurs due to variability and accuracy of the methods used to determine MNPs in different species of coral reef sponge, representing different functional growth forms [150][151][152]. Due to the important role sponges play in the reef system, from nutrient recycling to providing habitats, more work is required to fill this knowledge gap, and to understand whether sponge health and system function is impacted.…”

The leatherback turtle (Dermochelys coriacea) and plastics in the Northwest Atlantic ocean: A hazard assessment

“…Consequently, the presence of plastic debris within oceanic waters can adversely impact wildlife through entanglement, ingestion, and habitat degradation ( Nelms et al., 2016 ). The interactions of plastic and marine organisms are being investigated across the globe ( Consoli et al., 2018 ; Fallon and Freeman, 2021 ; Pereao et al., 2020 ; Ríos et al., 2020 ), including Canada ( Desforges et al., 2015 ). Canada's Atlantic bioregions, such as the Scotian Shelf, Gulf of St. Lawrence, and the Grand Banks ( Dever et al., 2016 ), are highly productive areas that serve as spawning, nursing, and feeding habitats for many organisms.…”