Marine biology: Sponges as biomonitors of micropollution

Date:
October 23, 2020
Source:
Ludwig-Maximilians-Universita"t Mu"nchen
Summary:
Sponges are filter feeders that live on particulate matter -- but
they can also ingest microscopic fragments of plastics and other
pollutants of anthropogenic origin. They can therefore serve as
useful bioindicators of the health of marine ecosystems.



FULL STORY ========================================================================== Sponges are filter feeders that live on particulate matter -- but they
can also ingest microscopic fragments of plastics and other pollutants
of anthropogenic origin. They can therefore serve as useful bioindicators
of the health of marine ecosystems.


========================================================================== Pollution of the world's oceans owing to anthropogenic input of
plastics and other industrial wastes represents an increasing threat
to the viability of marine ecosystems. -- And because such pollutants accumulate in fish, crustaceans and mollusks, they enter the food chain
and can be ingested by human consumers. Microparticles with dimensions
of less than 5 mm present a particularly insidious problem. This class of pollutants includes microplastics and textile fibers, as well as synthetic chemicals found in consumer products such as household cleansers and
cosmetics. It is therefore imperative to develop methods for quantifying
the magnitude of the threat in order to develop effective measures to
mitigate it. In a new publication in the journal Environmental Pollution,
a research team led by Ludwig-Maximilians-Universitaet (LMU) in Munich Professor Gert Wo"rheide (Department of Earth and Environmental Sciences,
and GeoBio-Center) shows that marine sponges have great potential as bioindicators for the monitoring of microscopic pollutants in the seas.

Sponges are sometimes referred to as the ocean's vacuum cleaners. They
feed on tiny particles suspended in the currents, by filtering them from
the seawater that passes through their highly porous tissues -- which
are supported by mineralized skeletons in many species. To assess their
utility as bioindicators for microparticulate pollutants, Wo"rheide and colleagues studied 15 samples of a type of mineralized sponges belonging
to the class known as 'demosponges' from a coral reef off the coast of
the island of Bangka in Northern Sulawesi (Indonesia). "We chose this
site because Southeast Asia is a hotspot for plastic pollutants in the
oceans," says Elsa B. Girard, lead author of the study. Girard recently graduated from the Master's Program in Geobiology and Paleobiology at LMU,
and her contribution to the paper was part of her Master's thesis. "In
light of the impact of global warming, and the overexploitation of
marine resources, local sponge species could act as useful biomonitors
of micropollutants, and help us to develop appropriate measures to
reduce the deleterious effects of these substances on reef communities,"
she explains.

In cooperation with specialists from the SNSB- Mineralogical State
Collection in Munich and LMU's Department of Chemistry and Center
for Nanoscience (CeNS), the biologists used two innovative methods to
examine the samples collected from the reef. With the aid of two-photon excitation microscopy (TPE), they confirmed that sponges indeed
incorporate microparticles into their tissues.

Then they used Raman spectroscopy to characterize the nature of the
particles themselves. The data obtained with the second technique revealed
the presence of no less than 34 different types of microparticles in
sponge tissues. The spectrum ranged from plastics such as polystyrene to
cotton and titanium dioxide (TiO2). TiO2 is used in dyes and paints, as
well as being a component of sunscreen lotions. Furthermore, the variation
in the composition of microparticles in the different samples appears
to reflect spatial variations in particle type in the surrounding water.

The researchers detected between 90 and 600 particles per gram of
dried tissue in their sponge samples. "Since sponges can weigh up to
several hundred grams, we estimate on the basis of these results that
each can accumulate more than 10,000 particles," says Wo"rheide. "This
makes them promising candidates for the task of monitoring the levels
of anthropogenic microparticle pollution in the oceans." With the
exception of mollusks, few other species have the properties required
of marine bioindicators. According to the authors of the study, sponges
have several other "qualifications" for the job. They are abundant
and are continuously active as filter-feeders. Moreover, measurements
of pollution levels can be carried out on tissue samples (biopsies)
without affecting the viability of the organisms.


========================================================================== Story Source: Materials provided by
Ludwig-Maximilians-Universita"t_Mu"nchen. Note: Content may be edited
for style and length.


========================================================================== Journal Reference:
1. Elsa B. Girard, Adrian Fuchs, Melanie Kaliwoda, Markus Lasut, Evelyn
Ploetz, Wolfgang W. Schmahl, Gert Wo"rheide. Sponges as
bioindicators for microparticulate pollutants? Environmental
Pollution, 2020; 115851 DOI: 10.1016/j.envpol.2020.115851 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/10/201023123135.htm

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