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Revista de BiologÃa Tropical, ISSN: 2215-2075, Vol. 71: e50031, enero-diciembre 2023 (Publicado 25 de enero, 2023)
environments that are especially susceptible to
this type of pollution. On one hand, beaches are
in fact, depositional environments that natural-
ly accumulate particles carried by surrounding
areas, including microplastics (Acosta-Coley
& Olivero-Verbel, 2015). In Latin America,
urban beaches are not only exploited as mass
tourist destinations but are also highly urban-
ized and subject to heavy industrial activi-
ties, such as ports or fisheries, making them
particularly vulnerable (Wright et al., 1979;
Wright & Short ,1984). Therefore, the impact
of microplastics pollution on urban beaches
often acts synergically with other human-driv-
en impacts, such as erosion and trampling,
collectively affecting local conditions, leading
to changes in the composition and variation of
the structure of the benthic communities and, in
particular the interstitial meiofauna (Gheskiere
et al., 2005; MartÃnez et al., 2020; Rangel-
Buitrago et al., 2015).
Interstitial meiofauna is an important com-
ponent of the biodiversity on marine sand
beaches, due to its high taxonomic richness and
abundance. Unfortunately, meiofaunal animals
are often neglected in biodiversity studies,
as their characterization requires specialized
sampling techniques and taxonomic expertise
(Curini-Galletti et al., 2012; MartÃnez et al.,
2019). This neglect is problematic not only
because it produces biased information about
actual biodiversity in many regions, but also
an incomplete view of ecosystem functioning.
Meiofaunal organisms provide important ser-
vices in marine ecosystems, such as the transfer
of energy from microbial production to higher
trophic levels, thus catalysing many geochemi-
cal processes in coastal environments (Giere,
2009). Meiofaunal assemblages comprise
almost all animal phyla, responding differential-
ly to specific physical-chemical environmental
factors and often showing a faster response
to changes (Zeppilli et al., 2015). Therefore,
studying the abundance and composition of
meiofaunal communities remains as a valuable
tool for environmental assessments, since they
allow a rapid detection of different types of
impacts at different temporal and spatial scales
(Alexeev & Galtsova, 2012; Alves et al., 2015).
Surprisingly, although experimental work has
shown that meiofauna are affected by micro-
plastics in different marine habitats (Fueser et
al., 2019; Fueser et al., 2020; Mueller et al.,
2020; Wakaff et al., 2020), few studies have
focused on the specific impact of microplastics
on the interstitial meiofaunal communities in
natural environments. Large accumulations of
microplastics in the marine sediment affects its
structure, and therefore (Carson et al., 2011)
could also affect the meiofauna.
Our case of study relies on several quali-
tative surveys done over the last ten years
around the coastal areas of Santa Marta, in
which different beaches have been sampled to
describe the diversity of organisms. These stud-
ies collectively forecasted the richness of the
meiofaunal communities in the sandy beaches
of Santa Marta region (Castro et al., 2021;
González-Cueto et al., 2014; Lagos et al., 2018;
Lagos, 2018; Sevilla-Hernández, 2016), and
highlighted the presence of microfibers and
debris. The co-occurrence of meiofauna and
microplastics raises the question on whether the
accumulation of microplastics in the sediments
might affect the abundance and composition of
the meiofaunal communities inhabiting those
beaches (Carson et al., 2011).
The main goal of this study is to investigate
the distribution of microplastics, in the three
main urban sandy beaches of the Santa Marta
region (Colombia), all with similar impacts in
terms of tourism, population, and wastewater
discharge. Our main hypothesis is that, since
microplastics are deposit in the sediment modi-
fying its structure, they might have an effect on
the abundance and composition of the intersti-
tial meiofaunal communities on these beaches.
MATERIALS AND METHODS
Area of study: This study was focused on
the only three beaches accessible in a radius
of 10 km from Santa Marta, Northern Colom-
bia, which exhibit a comparable sedimentary
regime and are affected by similar human-driv-
en impacts, such as erosion and trampling,