First Evidence of Mesoplastic Pollution in Beach Sediments of the Moroccan Mediterranean Coast

Abstract

The problem of marine plastic pollution is multifaceted and poses a serious threat to the ecosystem and human health. This work is the first investigation of mesoplastics (MEPs, 5 mm–2.5 cm) along the most representative beaches of the whole Mediterranean coast of Morocco. Surface sediment samples (0–5 cm), with 3 replicates each, were collected from thirty-three beaches to identify mesoplastic item characteristics (concentration, weight, type, size, color, and nature). The samples were collected between October and November 2021 and a total of 1998 mesoplastics (59.99 g kg⁻¹) were collected from the thirty-three beaches studied. The average concentrations ranged from 20.18 ± 13.93 MEP kg⁻¹ to 0.61 ± 0.61 g kg⁻¹, showing a great variability within each beach and between the beaches investigated. Mesoplastic fragments accounted for 43.92% of the total mesoplastic items, showed sizes from 5 to 10 mm (56.64%) and were predominantly white/transparent (43.36%). Fourier Transform Infrared Spectroscopy (FTIR) analysis revealed that Polyethylene (PE), Polypropylene (PP), Polystyrene (PS), and Polyvinyl chloride (PVC) were the most common polymers. The present results revealed a moderate level of mesoplastics pollution along the beaches investigated. Fishing, coastal activities, and wastewater discharges were probably the main sources. Furthermore, this study is likely to serve as a scientific baseline for monitoring and tracking mesoplastic pollution on Moroccan beaches.

1. Introduction

Marine debris is any persistent solid material or object, manufactured or used by people and unintentionally or intentionally discarded into the sea, rivers, or beaches [1]. Several studies conducted over the past few decades have revealed that plastics constitute a significant and increasing portion of marine debris found in coastal and marine environments [2,3,4]. Since the 20th century, plastics have become increasingly popular in a wide range of industries, including food, construction, transportation, healthcare, sports, electronics, and agriculture. The worldwide production of plastics reached 400.3 million metric tons in 2022 [5,6] and between 4.8 and 12.7 million tons of plastics are released onto oceans each year from coastal countries, where they persist for 400 to 1000 years [7].

Plastics are classified into four types based on their size: macro (>2.5 cm), meso (5–25 mm), micro (1 µm–5 mm) and nanoplastics (<1 µm). Depending on their sources, micro- and mesoplastic are classified into “primary” and “secondary”. Primary sources include plastics in the form of microbeads used in cosmetics or resin pellets to manufacture other products [8,9]. Secondary sources are linked to the decomposition of large plastic items due to chemical, biogeochemical, and physical degradation processes [10,11,12]. The main sources of plastic waste pollution in marine environments include marine sources (such as shipping, fishing, and maritime industries), land-based sources (such as rivers, stormwater runoff, sewage discharges, and tourism), and atmospheric deposition [13,14,15].

An increasing number of studies on micro- and mesoplastics have been documented in marine environments, including beaches, estuaries, mangroves, seagrass beds and the ocean sea surface [4,16,17]. Small plastic items constitute a persistent environmental hazard when enters into the marine environments. They can be mistakenly ingested by a wide range of organisms, producing negative impacts on their survival and well-being [18,19,20]. A study that carried out an extensive literature review and analysis of field observations found that at least 690 marine species have been exposed to marine litter, with 92% being especially exposed to plastic debris, and 10% of them specifically to microplastics. Furthermore, plastic items can serve as a vector for heavy metals or persistent organic pollutants (POPs), which are often added during their production or adsorbed from the marine environment [21,22,23].

In coastal sediments, the abundance of plastic debris varies greatly worldwide depending on the intensity of human activities, hydrodynamic conditions and sediment characteristics. Macroplastics are generally reported at densities ranging from 1 to over 200 items m⁻², particularly in coastal zones influenced by tourism or urban waste inputs [7,24]. Mesoplastics are commonly found at concentrations between 1 and 80 items kg⁻¹ in sediment, although higher values have been observed in regions subjected to intense fishing or recreational activities [25]. Microplastics are typically more abundant, ranging from 10 to more than 10,000 particles kg⁻¹ in estuarine or coastal systems affected by industrial and municipal discharges [26]. Nanoplastics are increasingly recognized in marine environments, but their quantification remains challenging due to methodological limitations [27].

The Mediterranean Sea is one of the areas most affected by plastic items pollution, accumulating up to 5–10% of global plastic mass [28]. Thus, the Mediterranean has been identified as the sixth greatest area in the world for the accumulation of marine debris, and numerous studies have been carried out to determine the amount of plastic items found there [7,29,30,31,32]. The main causes of litter accumulation in the Mediterranean basin are linked to the high density of coastal population, intensive fishing and maritime traffic activities and tourism, combined with natural factors such as the semi-enclosed nature and the specific hydrodynamic characteristics of the basin [33].

Although the number of studies on plastic pollution has increased in Morocco, there is still not a complete picture of the problem. Most studies have focused on micro- and macroplastics [34,35,36,37,38,39,40] but, to date, there are no data about the abundance and distribution of mesoplastics in the Moroccan coasts. This research offers the first baseline data on mesoplastic pollution along the Moroccan Mediterranean beaches by investigating their spatial distribution patterns and characteristics, such as type, size, color, and polymeric composition.

2. Materials and Methods

2.1. Study Area

Morocco has a privileged geographical position, located at the northwestern tip of the African continent, between the Atlantic Ocean to the west and the Mediterranean Sea to the north, and has two large maritime facades totaling a length of 3500 km, with a maritime area > 1 million km². The Morocco Atlantic coastline extends over approximately 3000 km and the Mediterranean coast over approximately 512 km [41]. The Moroccan Mediterranean coastline lies almost entirely at the base of the Rif massif, whose reliefs often plunge steeply into the sea. It is formed by different types of ecosystems, including coastal fringes, lagoons, estuaries, islands, beaches, capes and coastal cliffs [42]. The 33 Moroccan Mediterranean beaches selected are located between Saidia, at the eastern end, and Tangier, at the western end (Figure 1).

These beaches are representative of the characteristics of the Moroccan Mediterranean coastline, encompassing popular and frequently visited sites during the summer period, thereby reflecting the dynamics of beach use. Additionally, they include sites near the mouths of the main rivers that outflow into the Moroccan Mediterranean coast. These rivers, mostly small to medium in size, drain predominantly rural and agricultural catchments and show a typically Mediterranean flow pattern, with higher discharge during winter and spring and low or intermittent flow during the dry (summer) period. During rainy seasons, runoff carry land-based debris, mostly plastics, at the coast area [43,44].

Furthermore, these sites cover all beach typologies, namely rural (16), village (5), urban (7), and resort (5), as defined by the classification of Williams and Micallef [45], allowing for a comprehensive and balanced study of the coastline. The majority of these beaches are located in Site of Biological and Ecological Interest (SBEI) areas and National Parks [41]. The study area is subject to a considerable anthropogenic pressure linked to the high degree of urbanization, intense port activities, increasing fishing activities and the presence of coastal tourist facilities.

Figure 1. Location of the surveyed beaches along the study area ((SAI) Saïdia, (MSA) Marina Saïdia, (CEA) Cap de l’eau, (ARE) Kariat Arekmane, (FIR) Firma, (AMO) Al Mohandes, (OKD) Oued Kdem, (BEN) Beni Ensar, (EKA) El Kaleth, (IIF) Ifri Ifonasen, (SBN) Sidi Boussaid Nasar, (GHA) Ghansou, (SHS) Sidi Hsain, (TAZ) Tazaghine, (SDR) Sidi Driss, (SOU) Souani, (SFI) Sfiha, (ISL) Isli, (QUE) Quemado, (BAD) Badès, (CIR) Cala Iris, (JEB) Jebha, (STE) Stehat, (QAS) Quaa Assrasse, (OLA) Oued Laou, (MAR) Martil, (CNE) Cabo Negro, (RIN) Rincon, (RES) Restinga, (TPI) Tres Piedras, (Dal) Dalia, (TMU) Tanger Municipal, (TMA) Tangier Malabata). Geographic coordinates of all sampling sites are provided in

Table 1. Mesoplastic abundance in sediments of studied beaches (mean, items kg⁻¹ dw ± SD).

Code	Beaches	Coordinate System		Total MEPs	Fibers	Filaments	Films	Fragments	Foams	Pellets
SAI	Saïdia	35.0875556	−2.2258333	28 ± 18	0	8 ± 9.17	3.33 ± 5.77	16.67 ± 25.48	0	0
MSA	Marina Saïdia	35.113840	−2.301479	10.67 ± 2.31	0.67 ± 1.15	5.33 ± 6.11	0.67 ± 1.15	4 ± 6.93	0	0
CEA	Cap de l’eau	35.1417778	−2.4180556	14 ± 7.21	0	2.67 ± 4.62	5.33 ± 4.16	5.33 ± 2.31	0.67± 1.15	0
FIR	Firma	35.118390	−2.72439	52.67 ± 8.08	11.33 ± 2.31	27.33 ± 6.43	10 ± 2	4 ± 2	0	0
ARE	Kariat Arekmane	35.113680	−2.71663	12.33 ± 2.08	0	3 ± 1	1 ± 1	7.33 ± 1.15	1± 1	0
AMO	AL Mohandes	35.1217222	−2.7383611	9 ± 3	0	6 ± 2	1 ± 1	2 ± 0	0	0
OKD	Oued Kdem	35.200170	−2.850110	25.33 ± 15.28	1 ± 1.73	4.67 ± 3.06	7.33 ± 8.74	9.67 ± 4.93	2.67 ± 4.62	0
BEN	Beni Ensar	35.263662	−2.922505	49.33 ± 68.13	0.67 ± 1.15	5.33 ± 2.31	4.67 ± 4.62	32 ± 48.50	6.67± 11.55	0
EKA	EL Kaleth	35.2684722	−3.1433056	40 ± 57.24	0	3.67 ± 0.58	2 ± 3.46	32.67 ± 53.15	1 ± 1.73	0.67 ± 1.15
IIF	Ifri Ifonasen	35.223317	−3.203692	30 ± 24	2 ± 0	4 ± 0	9.50 ± 9.50	14.50 ± 14.50	0	0
SBN	Sidi Boussaid Nasar	35.208840	−3.281275	12.33 ± 2.52	0	8.33 ± 2.52	2.33 ± 1.53	1.67 ± 1.53	0	0
GHA	Ghansou	35.192694	−3.318917	13 ± 5	0	7 ± 5	1 ± 1	4 ± 0	1 ± 1	0
SHS	Sidi Hsain	35.197010	−3.442830	5.33 ± 4.16	0	2.67 ± 2.31	2 ± 2	0.67 ± 1.15	0	0
TAZ	Tazaghine	35.2038611	−3.5043611	3.33 ± 4.16	0	3.33 ± 4.16	0	0	0	0
SDR	Sidi Driss	35.2392222	−3.6133056	14 ± 14	0.67 ± 1.15	5.33 ± 1.15	4 ± 6.93	4 ± 5.29	0	0
SOU	Souani	35.197889	−3.854861	7.33 ± 1.15	0	4.67 ± 1.15	2 ± 2	0.67 ± 1.15	0	0
SFI	Sfiha	35.211389	−3.901000	47.33 ± 39.31	0	4 ± 2	0	43.33 ± 37.54	0	0
ISL	Isli	35.219341	−3.912301	9.33 ± 11.02	0.67 ± 1.15	7.33 ± 7.57	0	1.33 ± 2.31	0	0
QUE	Quemado	35.2449444	−3.9266111	25.33 ± 8.33	0.67 ± 1.15	6 ± 3.46	4 ± 4	14.67 ± 8.08	0	0
BAD	Badès	35.171017	−4.297218	3.33 ± 3.06	0	0.67 ± 1.15	0.67 ± 1.15	2 ± 2	0	0
CIR	Cala Iris	35.148218	−4.365325	14.67 ± 14.05	0	5.33 ± 6.11	0.67 ± 1.15	7.33 ± 7.02	1.33 ± 1.15	0
JEB	Jebha	35.204896	−4.679614	10 ± 2	0	8 ± 0	0.67 ± 1.15	0.67 ± 1.15	0.67 ± 1.15	0
STE	Stehat	35.348361	−4.956083	12.67 ± 9.87	0	5.33 ± 3.06	3.33 ± 4.16	4 ± 3.46	0	0
QAS	Quaa Assrasse	35.413112	−5.067114	39.33 ± 36.35	1.33 ± 1.15	18 ± 7.21	5.33 ± 6.11	14.67 ± 23.69	0	0
OLA	Oued Laou	35.449611	−5.090361	19.33 ± 16.17	0	6 ± 6.93	7.33 ± 1.15	6 ± 8.72	0	0
MAR	Martil	35.625944	−5.272194	27.33 ± 19.01	1.33 ± 2.31	4 ± 5.29	15.33 ± 13.01	2.67 ± 3.06	4 ± 2	0
CNE	Cabo Negro	35.664347	−5.284090	34 ± 14	0	7.33 ± 7.02	9.33 ± 3.06	14.67 ± 9.45	2 ± 3.46	0.67 ± 1.15
RIN	Rincon	35.687500	−5.323167	26 ± 28.35	0.67 ± 1.15	9.33 ± 5.03	7.33 ± 12.70	8.67 ± 10.26	0	0
RES	Restinga	35.775306	−5.346250	7.33 ± 5.03	0	4.67 ± 3.06	2 ± 2	0.67 ± 1.15	0	0
TPI	Tres Piedras	35.810000	−5.351139	18.67 ± 11.72	0	6.67 ± 7.02	2.67 ± 2.31	8.67 ± 3.06	0.67 ± 1.15	0
DAL	Dalia	35.905583	−5.477278	0	0	0	0	0	0	0
TMU	Tanger-Municipal	35.777532	−5.793753	24.67 ± 11.02	0	7.33 ± 2.31	2 ± 0	14 ± 10	0	1.33 ± 1.15
TMA	Tanger-Malabata	35.777500	−5.779306	20 ± 9.17	0	4.67 ± 3.06	0	10 ± 5.29	4 ± 6.93	1.33 ± 1.15
Mean				20.18 ± 13.93	0.64 ± 1.99	6.24 ± 4.87	3.54 ± 3.67	8.86 ± 10.19	0.78 ± 1.52	0.12 ± 0.35
Median				14.67	0	5.33	2	5.33	0	0

and

Table 2. Mesoplastic weight abundance in sediments of studied beaches (mean, g. kg⁻¹ dw ± SD).

Code	Beaches	Coordinate System		MEP Weight	Fibrous MEP	Films	Fragments	Foams	Pellets
SAI	Saïdia	35.0875556	−2.2258333	1.520 ± 1.773	0.020 ± 0.020	0.313 ± 0.543	1.187 ± 2	0	0
MSA	Marina Saïdia	35.113840	−2.301479	0.123 ± 0.154	0.012 ± 0.010	0.012 ± 0.020	0.100 ± 0.173	0	0
CEA	Cap de l’eau	35.1417778	−2.4180556	0.573 ± 0.200	0.010 ± 0.017	0.100 ± 0.061	0.457 ± 0.260	0.007± 0.012	0
FIR	Firma	35.118390	−2.72439	0.237 ± 0.049	0.147 ± 0.015	0.050 ± 0.020	0.040 ± 0.020	0	0
ARE	Kariat Arekmane	35.113680	−2.71663	0.593 ± 0.138	0.008 ± 0.003	0.002 ± 0.003	0.567 ± 0.123	0.017± 0.021	0
AMO	AL Mohandes	35.1217222	−2.7383611	0.042 ±0.010	0.013 ± 0.003	0.003 ± 0.003	0.027 ± 0.015	0	0
OKD	Oued Kdem	35.200170	−2.850110	0.120 ± 0.101	0.012 ± 0.010	0.027 ± 0.025	0.055 ± 0.033	0.027 ± 0.046	0
BEN	Beni Ensar	35.263662	−2.922505	1.772 ± 2.237	0.012 ± 0.003	0.013 ± 0.006	1.707 ± 2.159	0.040± 0.069	0
EKA	EL Kaleth	35.2684722	−3.1433056	2.395 ± 4.114	0.010 ± 0.005	0.020 ± 0.035	2.355 ± 4.066	0.003 ± 0.006	0.007 ± 0.012
IIF	Ifri Ifonasen	35.223317	−3.203692	0.782 ± 0.765	0.015 ± 0	0.050 ± 0.050	0.717 ± 0.715	0	0
SBN	Sidi Boussaid Nasar	35.208840	−3.281275	0.052 ± 0.012	0.020 ± 0.009	0.015 ± 0.013	0.017 ± 0.015	0	0
GHA	Ghansou	35.192694	−3.318917	0.213 ± 0.093	0.023 ± 0.018	0.005 ± 0.005	0.155 ± 0.085	0.030 ± 0.030	0
SHS	Sidi Hsain	35.197010	−3.442830	0.155 ± 0.243	0.008 ± 0.008	0.017 ± 0.015	0.130 ± 0.225	0	0
TAZ	Tazaghine	35.2038611	−3.5043611	0.005 ± 0.005	0.005 ± 0.005	0	0	0	0
SDR	Sidi Driss	35.2392222	−3.6133056	0.272 ± 0.366	0.022 ± 0.016	0.027 ± 0.046	0.223 ± 0.304	0	0
SOU	Souani	35.197889	−3.854861	0.077± 0.065	0.012 ± 0.008	0.063 ± 0.065	0.002 ± 0.003	0	0
SFI	Sfiha	35.211389	−3.901000	2.037± 1.842	0.010 ± 0	0	2.027 ± 1.842	0	0
ISL	Isli	35.219341	−3.912301	0.115 ± 0.186	0.018 ± 0.019	0	0.097 ± 0.167	0	0
QUE	Quemado	35.2449444	−3.9266111	0.865 ± 0.581	0.022 ± 0.025	0.073 ± 0.095	0.770 ± 0.528	0	0
BAD	Badès	35.171017	−4.297218	0.355 ± 0.527	0.002 ± 0.003	0.020 ± 0.035	0.333 ± 0.493	0	0
CIR	Cala Iris	35.148218	−4.365325	0.621 ± 0.551	0.008 ± 0.010	0.005 ± 0.008	0.587 ± 0.522	0.021 ± 0.019	0
JEB	Jebha	35.204896	−4.679614	0.084 ± 0.075	0.024 ± 0.010	0.013 ± 0.023	0.033 ± 0.058	0.013 ± 0.023	0
STE	Stehat	35.348361	−4.956083	0.510 ± 0.627	0.010 ± 0.005	0.113 ± 0.147	0.387 ± 0.488	0	0
QAS	Quaa Assrasse	35.413112	−5.067114	0.995 ± 1.560	0.041 ± 0.019	0.067 ± 0.070	0.887 ± 1.484	0	0
OLA	Oued Laou	35.449611	−5.090361	0.632 ± 0.977	0.015 ± 0.022	0.087 ± 0.064	0.530 ± 0.892	0	0
MAR	Martil	35.625944	−5.272194	0.360 ± 0.300	0.030 ± 0.035	0.073 ± 0.050	0.200 ± 0.280	0.057 ± 0.032	0
CNE	Cabo Negro	35.664347	−5.284090	0.929 ± 0.437	0.015 ± 0.015	0.173 ± 0.127	0.687 ± 0.474	0.020 ± 0.035	0.033 ± 0.058
RIN	Rincon	35.687500	−5.323167	0.435 ± 0.425	0.029 ± 0.028	0.047 ± 0.081	0.360 ± 0.433	0	0
RES	Restinga	35.775306	−5.346250	0.082 ± 0.068	0.009 ± 0.004	0.060 ± 0.053	0.013 ± 0.023	0	0
TPI	Tres Piedras	35.810000	−5.351139	0.746 ± 0.429	0.018 ± 0.020	0.041 ± 0.036	0.667 ± 0.363	0.020 ± 0.035	0
DAL	Dalia	35.905583	−5.477278	0	0	0	0	0	0
TMU	Tanger-Municipal	35.777532	−5.793753	1.123 ± 0.761	0.017 ± 0.012	0.057 ± 0.015	1.007 ± 0.786	0	0.043 ± 0.038
TMA	Tanger-Malabata	35.777500	−5.779306	1.179 ± 0.367	0.013 ± 0.015	0	1.093 ± 0.291	0.040 ± 0.069	0.033 ± 0.031
Mean				0.606 ± 0.614	0.019 ± 0.024	0.047 ± 0.062	0.528 ± 0.600	0.009 ± 0.015	0.004 ± 0.011
Median				0.435	0.013	0.027	0.360	0	0

.

Figure 1. Location of the surveyed beaches along the study area ((SAI) Saïdia, (MSA) Marina Saïdia, (CEA) Cap de l’eau, (ARE) Kariat Arekmane, (FIR) Firma, (AMO) Al Mohandes, (OKD) Oued Kdem, (BEN) Beni Ensar, (EKA) El Kaleth, (IIF) Ifri Ifonasen, (SBN) Sidi Boussaid Nasar, (GHA) Ghansou, (SHS) Sidi Hsain, (TAZ) Tazaghine, (SDR) Sidi Driss, (SOU) Souani, (SFI) Sfiha, (ISL) Isli, (QUE) Quemado, (BAD) Badès, (CIR) Cala Iris, (JEB) Jebha, (STE) Stehat, (QAS) Quaa Assrasse, (OLA) Oued Laou, (MAR) Martil, (CNE) Cabo Negro, (RIN) Rincon, (RES) Restinga, (TPI) Tres Piedras, (Dal) Dalia, (TMU) Tanger Municipal, (TMA) Tangier Malabata). Geographic coordinates of all sampling sites are provided in Table 1 and Table 2.

2.2. Sampling and Analysis

Mesoplastics present in beach sediments were sampled using sampling methodologies and protocols based on the European MSFD program [46] and GESAMP protocol [47]. At each site, three replicate samples were collected from the top 5 cm of sediment using a 1 m² wooden quadrant, with samples taken from the shoreline and spaced at least 25 m apart. Approximately 4 kg of sand sediment with one sample for each quadrant was collected and stored. These samples were stored in aluminum containers and transported to the laboratory. A total of 99 sediment samples were collected from 33 beaches throughout the Moroccan Mediterranean coast. Sampling was carried out with a metal trowel and using latex gloves and cotton garments to minimize contamination [48]. Sample collection was carried out between October and November 2021, before the beginning of winter rains and marine storms.

In the laboratory, the samples were dried at 60 °C for 48 h, then 1 kg of dried sediments was taken and sieved through 25 and 5 mm mesh stainless steel sieves. Larger-sized plastics (>25 mm) were excluded from the study. The plastic items retained on the 5 mm mesh were measured and classified as mesoplastic items (5–25 mm). Subsequently, density separation was performed on the remaining sediment fraction to collect the visually unidentified mesoplastics [49,50,51,52]. This involved mixing the whole sediment sample with a saturated solution of sea salt. The mixture was stirred for 30 min at 1000 rpm, and then allowed to stand for 2 h for low-density items to rise to the surface and float. Floating mesoplastic items were then collected by filtering the supernatant with Whatman filters and the extraction process was performed twice, for each sample. Filters were then placed in glass Petri dishes and dried at 60 °C for 24 h. The dried filter papers were inspected under a binocular microscope. The collected mesoplastics were classified based on their size, color and type [53].

2.3. FTIR Spectroscopy for Polymer Identification

A total of 63 mesoplastic items, comprising 37 fragments, 12 films, 7 foams, 4 filaments and 3 pellets, were selected for analysis by Fourier Transform Infrared (FTIR) spectroscopy. The FTIR spectra were acquired over a wavelength range of 650–4000 cm⁻¹, with 32 scans. The obtained spectra were then automatically compared to reference spectra from the FTIR library, and the polymer with the highest similarity percentage was identified.

2.4. Statistical Analysis

All statistical analyses were carried out using SPSS Statistics software (22.0, IBM, Armonk, NY, USA). The normality distribution of data was checked using the Shapiro–Wilk test. To compare the abundance of mesoplastics between different sampling sites, the Kruskal–Wallis test for multiple comparisons was used, as the data did not meet the assumptions of normality. If this test indicated significant differences, the Mann–Whitney U test for pairwise comparisons was performed. In addition, Spearman’s rank correlation coefficient was used to determine whether a significant correlation existed between the size of mesoplastic items and their abundance on beaches, as the mesoplastic abundance data did not follow a normal distribution. Tests with p < 0.05 were considered statistically significant. ArcGIS (10.3, Esri, Redlands, CA, USA) was used for the geographic location of the studied beaches. The identified mesoplastics were counted and weighed for each replicate sample: abundance (mean number detected in the 3 replicates) is expressed as items kg⁻¹ dw (dry weight) and weight (mean weight detected in the 3 replicates) as g kg⁻¹ dw (dry weight).

3. Results

3.1. Abundance and Distribution of Mesoplastics

Mesoplastics were present in all sampled sites (except Dalia), with a total of 1998 items that were sorted from the 99 samples collected from the 33 beaches investigated, with concentrations ranging from 0 MEP kg⁻¹ at Dalia to 52.67 ± 8.08 MEP kg⁻¹ at Firma. The mean concentration of mesoplastic items for all sites was 20.18 ± 13.93 MEP kg⁻¹ (median: 14.67 MEP kg⁻¹) (Table 1). The total weight summed 59.99 g kg⁻¹, with an overall mean of 0.61 ± 0.61 g kg⁻¹ (median: 0.44 g kg⁻¹). The highest values were recorded at El Kaleth (2.40 ± 4.11 g kg⁻¹) and Sfiha (2.04 ± 1.84 g kg⁻¹) (Table 2). Statistical analysis revealed significant differences in mesoplastic abundance along the 33 beaches, both in terms of number (p = 0.027, Kruskal–Wallis H test) and weight (p = 0.028, Kruskal–Wallis H test).

3.2. Mesoplastic Type, Color, and Size

Regarding the types of mesoplastics collected on beaches, fragments, with 878 items or 43.92% of the total, constituted the most numerous type. The second largest type was fibrous, representing 34.08% (681 items, with filaments: 30.93% and fibers: 3.15%) of the total, followed by films (17.54%, 351 items), foams (3.85%, 77 items) and pellets (0.60%, 12 items) (Table 1, Figure 2). In terms of weight, fragments were the most significant type, accounting for 87.08% (52.24 g) of the total weight of collected items. Films represented the second type in terms of weight, with 7.73% (4.64 g) of the total weight of collected items, followed by fibrous mesoplastics (3.13%, 1.88 g), foams (1.47%, 0.88 g) and, finally, pellets (0.58%, 0.35 g) (Table 2, Figure 3).

The coefficient of variation (CV) for the abundance of the five types of mesoplastics detected (fibers, fragments, films, foams, and pellets) was >1.0, implying a high variation in their abundance in the sediment samples analyzed, while the coefficient of variation for filaments was <1.0, indicating a low spatial variation compared to the other types. The Kruskal–Wallis test revealed that the abundance of fragments (p = 0.047), fibers (p = 0.005), films (p = 0.04), and pellets (p = 0.015) in beach sand varied significantly among sampling sites at the p < 0.05 level, while filaments (p = 0.129) and foams (p = 0.058) did not differ significantly (p > 0.05).

Mesoplastics were found in a wide range of colors, including white, translucent, red, orange, blue, black, gray, brown, green, pink, yellow, and purple. Transparent mesoplastics (24.77%) were the most frequent, followed by blue (21.72%) and white (18.59%). Mesoplastics colored green (8.46%), brown (4.95%), black (4.50%), red (3.93%), orange (3.85%), gray (2.95%), pink (2.65%), yellow (2.55%) and purple (1.05%) were found in small proportions (Figure 4). Only orange and red mesoplastics showed significant spatial variability between different sampling sites (Kruskal–Wallis test, p = 0.031; p = 0.022).

Mesoplastic items were separated into four size classes: 5–10 mm, 10–15 mm, 15–20 mm and 20–25 mm (Figure 5). This study revealed that the size of mesoplastics ranged from a minimum of 5.01 mm to a maximum of 25 mm, with a mean of 11.26 ± 5.68 mm. Films had the largest average major dimension (12.74 ± 6.13 mm), followed by fibers (12.52 ± 7.41 mm), filaments (11.55 ± 6.01 mm), fragments (10.76 ± 5.16 mm), foams (8.20 ± 3.60 mm), and pellets (5.50 ± 0.34 mm). The size fraction with the highest proportion of mesoplastics was 5–10 mm (56.36%), followed by the size classes 10–15 mm and 15–20 mm, respectively, representing 20.60% and 13.76% of the total. The lowest amount was measured in the size range of 20 to 25 mm, with a percentage of 9.28%. Spearman correlation analysis revealed a statistically significant negative correlation between the size and abundance of mesoplastics in all sampling sites (Spearman’s ρ = −0.73, p = 0.00).

Concerning the fragments, which represented the most dominant type, their average concentration was 8.86 ± 10.19 fragments kg⁻¹ (Table 1, Figure 2). High fragment abundances with values above average were detected in Sfiha (43.33 ± 37.45 fragments kg⁻¹), El Kaleth (32.67 ± 53.15 fragments kg⁻¹) and Beni Ensar (32 ± 48.50 fragments kg⁻¹). In terms of weight, the average abundance for each beach was 0.53 ± 0.60 g kg⁻¹. The highest values were recorded at El Kaleth (2.36 ± 4.07 g kg⁻¹) and Sfiha (2.03 ± 1.84 g kg⁻¹) beaches (Table 2, Figure 3). The majority of fragments found in the study area were irregular (angular: 90.37%, subangular: 7.01%), rounded and subrounded fragments represented only 0.91% and 1.71%, respectively. The most frequently encountered colors were blue (33.85%), white/cream (21.88%), green (16.87%) and red (7.58%). Other colors did not exceed 19.83% (orange: 4.90%, yellow: 2.96%, transparent: 2.85%, gray: 2.62%, purple: 2.17%, pink: 2.05%, brown: 1.82%, black: 0.46%) (Figure 4). Fragments were found in all size fractions, being more prevalent in the 5–10 mm class size, which presented 58.12% of the total fragments (Figure 5).

Fibrous mesoplastics were the second most abundant type (34.08%). Fibers were relatively poorly represented (3.15%, 63 articles) and were identified on eleven out of the thirty-three beaches examined (Table 1, Figure 2) with an average concentration of 0.64 ± 1.99 fibers kg⁻¹. Firma beach showed the highest values, with an average of 11.33 ± 2.31 fibers kg⁻¹. They were mainly (77.78%) composed of simple fibers. The most frequently reported fiber colors were white (60.32%) and pink (14.29%); other colors showed lower frequencies (black: 9.52%, red: 6.35%, blue: 6.35% and orange: 3.17%) (Figure 4). The fibers appeared in all size classes with varying quantities, but most frequently in the 5–10 mm size class, which represented 44.44% of total fibers (Figure 5). Filaments were collected from all beaches (except Dalia), with fairly variable concentrations: from 27.33 ± 6.43 filaments kg⁻¹ at Firma to 0.67 ± 1.15 filaments kg⁻¹ at Badès, and an overall average of 6.24 ± 4.87 filaments kg⁻¹ (Table 1, Figure 2). Single filaments represented 97.57% of the total number. Transparent filaments were the most dominant (55.83%), followed by brown (13.43%), black (11.33%), blue (8.25%), white (4.53%), pink (2.91%), green (2.10%), red (0.97%), and orange (0.65%) colored filaments (Figure 4). Filaments were found in all size fractions, with the highest prevalence in the 5–10 mm size class (57.77%) (Figure 5).

In terms of weight, fibrous items had an overall average of 0.02 ± 0.02 g kg⁻¹. Firma Beach recorded the highest items weight, i.e., 0.147 ± 0.02 g kg⁻¹ (Table 2, Figure 3).

Films, with an average value of 3.54 ± 3.67 items kg⁻¹ (Table 1, Figure 2), were observed on twenty-eight out of the thirty-three beaches examined and represented 17.54% of all mesoplastics recorded. In this mesoplastic type, Firma (10 ± 2 films kg⁻¹) and Martil (15.33 ± 13.01 films kg⁻¹) beaches exhibited the highest values. The weight of the collected films ranged from 0.31 ± 0.54 to 0.002 ± 0.003 g kg⁻¹ recorded, respectively, at Saidia and Kariat Arekmane beaches; the average value recorded for all beaches was 0.05 ± 0.06 g kg⁻¹ (Table 2, Figure 3). The majority of the films discovered had irregular shapes (87.30%) and only 12.70% of the total had regular shapes. Transparent films were the most prevalent (35.66%), followed by blue (21.11%), white (13.84%), gray (10.27%), yellow (6.56%), orange (5.14%) and other colors, encountered with a frequency lower than 7.42% (Figure 4). The majority of films were in the 5–10 mm size class, representing 47.08% of the total (Figure 5).

Other types of mesoplastics were poorly represented and only summed to circa 4.45% of the total. On twelve out of the thirty-three beaches studied, foams represented 3.85% of all mesoplastic types found and an average of 0.78 ± 1.52 foams kg⁻¹. The highest values were observed at Beni Ensar (6.67 ± 11.55 foams kg⁻¹), Martil (4 ± 2 foams kg⁻¹) and Tangier-Malabata (4 ± 6.93 foams kg⁻¹) beaches (Table 1, Figure 2). In terms of weight, the average value recorded for all beaches was 0.01 ± 0.01 g kg⁻¹. The highest abundance was recorded at Martil (0.06 ± 0.03 g kg⁻¹) (Table 2, Figure 3). The majority of foams were irregularly shaped (angular: 36.36%, subangular: 35.06%), 25.97% were subrounded and 2.60% were rounded. The most common color of foams was white (76.62%), followed by blue (10.39%), orange (10.39%) and yellow (2.60%) (Figure 4). All foams were <20 mm, with 70.13% in the 5–10 mm size fraction (Figure 5).

Pellets were observed on four out of the thirty-three beaches studied, with an average value of 0.12 ± 0.35 pellets kg⁻¹ (Table 1, Figure 2). High concentrations of pellets, i.e., above the described average value, were recorded in Tangier-Municipale (1.33 ± 1.15 pellets kg⁻¹) and Tangier-Malabata (1.33 ± 1.15 pellets kg⁻¹). The weight of the pellets collected ranged from 0.043 ± 0.038 to 0.007 ± 0.0115 pellets kg⁻¹ recorded, respectively, at Tangier-Municipale and El Kaleth beaches, with an overall average for all beaches of 0.004 ± 0.011 pellets kg⁻¹ (Table 2, Figure 3). Cylindrical and spherical pellets accounted for 50% and 33.33% of the total pellets, respectively; only 16.67% of all pellets had a lenticular shape. Only three colors were detected in the case of pellets: white (50%), black (33.33%) and orange (16.67%) (Figure 4). All pellets belonged to the 5–10 mm size fraction (Figure 5).

Analysis of mesoplastic composition revealed that 60 out of 63 selected items were composed of synthetic polymers, as confirmed by FTIR spectroscopy. The other three items were identified as cardboard (1 filament and 1 film) and NOPI (1 fragment). The predominant polymer types identified were polyethylene (PE, 24 items), followed by polypropylene (PP, 14), polystyrene (PS, 9), polyvinyl chloride (PVC, 6), polyethylene terephthalate (PET, 3), and smaller amounts of polyamide (PA, 1), styrene allyl alcohol (SAA, 1), styrene-butadiene copolymer (SBC, 1), and polyurethane (PU, 1 items) (Figure 6). Mesoplastic fragments were mainly composed of PE (20 items), followed by PP (7), PS (5), PVC (3), and smaller proportions of PET (1 items). The film items were mainly composed of PP (4), PVC (3), PE (2), PET (1) and PA (1) polymers. All filament items were identified as PP (3). Pellets were identified as PE (2 items) and SBC (1) and foams were identified as PS (4), PET (1), SAA (1) and PU (1).

4. Discussion

This study evaluated for the first time the mesoplastic occurrence in beach sediments along the Moroccan Mediterranean coast. A significant spatial difference in abundance was found between different sites (p = 0.027, Kruskal–Wallis H test). Similarly, Grini et al. [54] reported a statistical difference between different sites in their study on plastic pollution in beach sediments of the Skikda coast (northeast of Algeria). A similar behavior was observed by Jeyasanta et al. [53] in the Tuticorin district (southeast coast of India), by Abdelkader et al. [55] in three sandy beaches on the northeastern Tunisian coast and by Cocozza et al. [56] on 31 beaches in Galicia and Asturias (Spain) and northern Portugal. In contrast to the present paper, Lee et al. [57] found no significant differences in mesoplastic items on 20 beaches along the South Korean coast.

It is also important to note that the sampling was conducted between October and November 2021, before the onset of winter rains and marine storms. Therefore, the observed spatial differences and overall abundances mainly reflect pre-winter beach conditions. Seasonal variability in mesoplastic occurrence is likely, as rainfall, river discharges, storm events, and human activities can influence the input and redistribution of plastics along the coast. Future investigations covering different seasons would be valuable to better assess temporal variations and their influence on mesoplastic dynamics.

The average amount of mesoplastic items ranged from 0 to 52.67 ± 8.08 MEP kg⁻¹ (mean: 20.18 ± 13.93 MEP kg⁻¹) and from 0 to 2.40 ± 4.11 g kg⁻¹ (mean: 0.61 ± 0.47 g kg⁻¹). The obtained values are slightly higher than in the northeastern Algerian coast, with 32 ± 17 MEP Kg⁻¹ [54], and central Italy [58] but greatly lower than that (100 ± 44 MEP kg⁻¹) reported by Scopetani et al. [59] on the sandy beach of the Migliarino San Rossore (Pisa, Italy). A comparison of mesoplastic abundance in different coastal regions is summarized in

Table 3. Comparative study of mesoplastic abundance in various coastal regions.

Region	Range (Min–Max) (MEPs kg−1)	Mean Abundance (MEPs kg−1)	Size Range (mm)	Predominant Shapes	Reference
Torre Flavia Natural Monument (Italy)	7–48 items m−2	24.4 ± 11.28 items m−2	5–25 mm	Pellets and Fragments	[58]
Migliarino San Rossore Coast (Italy)	71 ± 26–130 ± 37	100 ± 44	5–25	Fragments	[59]
Northeastern Tunisian Coast (Tunisia)	ND	36.26 ± 49.67 (items/m2)	5–25	Fragments	[55]
Skikda Coast (Algeria)	14.07–56.30	32.30 ± 17.44	5–25	Fragments	[54]
Tuticorin Coast (India)	ND	9.37 ± 0.5 (items/m2)	5–25	Fibers	[53]
Western Mediterranean Pelagic Zone	0–1300 (items/m2)	90 ± 250 (items/m2)	>5 mm	Fragments	[60]
Mediterranean Coast (Morocco)	0–52.67± 8.08	20.18 ± 13.93	5–25	Fragments	Present study

.

The highest concentrations of mesoplastics appeared at the Firma and Beni Ensar beaches, with, respectively, 52.67 ± 8.08 and 49.33 ± 68.13 MEP kg⁻¹. These beaches together concentrated approximately 15.3% of the total mesoplastics identified. Mann–Whitney pairwise comparison revealed non-significant variations in mesoplastics abundance between Firma and Beni Ensar (p = 0.601). Their high abundance can be attributed to their proximity to the conurbation of Nador-Melillia, which presents two large ports and whose economy is mainly based on artisanal fishing and seaside tourism [39].

Furthermore, a significant concentration of mesoplastics was found on Sfiha beach in Al Hoceima (47.33 ± 39.31 MEP kg⁻¹). This accumulation is likely associated with recreational beach tourism, the main economic activity in the area; tourists dump on the beach plastic items such as bottles, food packaging, and disposable consumer products. No mesoplastics were observed at Dalia beach. This is probably due to the rural nature of the beach and the absence of rivers flowing into this area [40]. In addition to local sources such as coastal cities, ports, river discharges, and tourism activities, hydrodynamic conditions also influence the spatial distribution of mesoplastics along the Moroccan Mediterranean coast. The prevailing eastward-flowing coastal current and wave-induced drift can transport floating debris from one beach to another, promoting both accumulation and dispersion depending on the degree of coastal exposure and geomorphological features [61,62]. Furthermore, the hydrological exchange between the Atlantic Ocean and the Mediterranean Sea through the Strait of Gibraltar may also contribute to the supplies of such particles. The Atlantic surface inflow, which moves eastward into the Mediterranean, can act as a transport pathway for floating debris that may eventually accumulate along the Moroccan Mediterranean coast [63,64]. Such processes may partially explain the spatial variability observed in mesoplastic abundance.

Results obtained at Dalia beach reflect recent investigations [39,40] on microplastics on Moroccan Mediterranean beaches, with high levels recorded at Firma (230 ± 59.63 items kg⁻¹) and Beni Ensar (101.33 ± 46.23 items kg⁻¹), and lower levels at Dalia beach (22 ± 7.21 items kg⁻¹), therefore indicating a probable correlation between microplastics and mesoplastics abundance.

Mesoplastics were classified into five shape types based on their morphological characteristics, namely fibrous (fibers and filaments), fragments, films, foams and pellets. Tire wear particles (TWPs), common in microplastics, were not observed among the mesoplastic particles, likely because most TWPs are small (<5 mm) and the few larger particles usually are rapidly fragmented by different processes. Another relevant issue is the rural and semi-rural nature of most studied beaches that have no well-developed road networks around and, therefore, limited road inputs.

Similar types have been found in a study conducted by Faure et al. [60] in pelagic ecosystems of the western Mediterranean, on the Northeast Levantine coast of Turkey [65] and in the Torre Flavia wetland in Italy [33]. Along the study area of this paper, the most common mesoplastics were fragments (43.92%) followed by fibrous (34.08%); such results corroborate the study of Caldwell et al. [66] on several sandy beaches of the Tyrrhenian and Ligurian Seas and Abdelkader et al. [55] who found the same five types of mesoplastics recorded in this paper and a predominance of fragments and fibers on the sandy beaches of the northeastern Tunisian coast.

The predominance of angular and irregularly shaped mesoplastics (i.e., 97.38% of fragments were angular or sub-angular; 87.30% of films were irregularly shaped; and 71.42% of foams were angular or subangular) compared to pellets, suggests that the source of mesoplastics is related to the degradation of large plastic items. Indeed, this composition of mesoplastics largely reflected the typology and composition of micro- [39,40] and macroplastics [35,36,37] present on these beaches.

In terms of weight, fragments were the most dominant (87.08%) type, followed by films (7.73%), fibrous (3.13%), foams (1.47%), and pellets (0.58%). Such results are consistent with those of Faure et al. [60] in the pelagic ecosystems of the Western Mediterranean, where fragments (87%), films (9%), and filaments (14.49%) are the most common forms in terms of weight.

In total, eleven different colors of mesoplastics were found in the collected samples. The variety of mesoplastic colors indicates a wide range of sources [67]. Transparent (24.77%) and blue (21.72%) were the most common colors. Nearly 43.36% of the mesoplastics found showed light colors (transparent and white). The most abundant color of microplastics reported on sandy beaches of the Moroccan Mediterranean coast was white/transparent [39,40], which is in line with the results observed in this paper and in Lake Setúbal in Portugal [68], in the Torre Flavia wetland in Italy [33], on the island of Gran Canaria in Spain [69], on riverine beaches of the lower Paraná River in Argentina [70], on beaches in Tunisia [55] and Algeria [54], in Turkey [65] and in India [53]. This result is of great ecological relevance because fishes and invertebrates are more likely to ingest transparent and white mesoplastics [68]. The prevalence of white and transparent plastics observed at the studied sites could be attributed to long-term environmental weathering. Prolonged exposure to ultraviolet (UV) radiation, saline conditions, and mechanical abrasion promotes photo-oxidative degradation and surface erosion, leading to color changes, including whitening and increased transparency, of the original material [33].

The average size of mesoplastics in the present study ranged from 5.5 mm (pellets) to 12.7 mm (films) in all the sampling sites. The majority of the mesoplastics (56.64%) at all beaches studied were between 5 and 10 mm in size. Items of 20–25 mm represented the smallest part of the total mesoplastics (9.28%). Spearman’s rank correlation revealed a negative and significant correlation between size and amount of mesoplastics (Spearman’s ρ = −0.73, p = 0.00). Further, the abundance of mesoplastics increased with decreasing size, and this is consistent with results obtained in river sediments of the Rhine-Main region in Germany by Klein et al. [71], on Fernando de Noronha beaches and in sediments of the estuarine system in Brazil [72,73], in the northeastern coast of the Levant in Turkey [65], in sediments of the Wei River, northwest China [74] and in sediments of the northern Yellow Sea [75]. However, values recorded in this paper were different from many other previous studies, including those carried out in coastal pelagic ecosystems of the northeast Pacific Ocean [76,77], in the North Atlantic Ocean [78] and in beach sediments of the Portuguese coast [79], where plastic debris > 10 mm were predominantly found. The higher percentage of smaller irregular mesoplastics (fibrous, fragments, films and foams) suggests that plastic items may have undergone significant weathering and fragmentation in the study area [80].

Fragments were the most abundant plastic type, representing 43.92% of all mesoplastics. Similar results were found in other regions such as Spain [69], Tunisia [55], Algeria [54], Turkey [65], the Ligurian and Tyrrhenian Seas [66], and the Western Mediterranean [60]. Based on a pairwise comparison, the proportion of fragments on the beaches of Sfiha (43.33 ± 37.45 fragments kg⁻¹), El Kaleth (32.67 ± 53.15 fragments kg⁻¹) and Beni Ensar (32 ± 48.50 fragments kg⁻¹) was significantly higher than on all other sites studied. The majority of fragments detected on the beaches of Sfiha, El Kaleth and Beni Ensar were predominantly angular to subangular (100%, 100%, 92%, respectively) and presented bright and fresh colors (blue, 31% and green, 20%), which suggests a relatively short residence time of these items [81]. The high proportion of fragments found on Sfiha beach is probably due to the tourist activities present in the region. However, the high concentration of fragments observed on the beaches of Beni Ensar and El Kaleth can be attributed to their proximity to the operational port of Beni Ensar and to the large Nador West-Med port, which is still under construction, as well as to their vicinity to the mouth of the Oued Kert River. The river likely carries debris from inland sources, while port-related inputs may result from fishing, ferry and cargo activities, and vessel maintenance at Beni Ensar, together with plastic losses associated with construction and infrastructure works at Nador West-Med. High concentrations of microfragments were also recorded at El Kaleth (60 ± 91.85 fragments kg⁻¹) and Beni Ensar (44.67 ± 35.57 fragments kg⁻¹); the majority of these fragments were angular to subangular (87.8%, 68%) on these beaches [39]. Previous observations suggest that microfragments reported by Azaaouaj et al. [39] were originated, at least in part, from the decomposition and fragmentation of mesoplastics at these sites.

Fibrous mesoplastics were the second most abundant type after fragments, a result consistent with other previous studies [33,55,66,82]. In this paper, the separation between fibers (degraded textiles) and filaments (fishing lines) allowed the clarification of the source of fibrous mesoplastics in the area evaluated. A high abundance of fibers, above the average value, was detected at Firma (11.33 ± 2.31 fibers kg⁻¹). The majority of mesoplastic fibers discovered at this site could have originated from wastewater discharges following the washing of clothing made from synthetic materials [83,84,85]. The presence of fibers in this area is consistent with a study on microplastics [39] that showed the predominance of fibers originated from domestic washing of clothes in the agglomerations of Nador-Melilla (Firma, Arekmane, Al Mohandes, Oued Kdem and Beni Ensar). Nearly 39.68% of the mesoplastic fibers observed in beach sediments were colored. Synthetic fabrics could be the main reason for the presence of colored fibers in the study area; refs. [15,86] reported that the main source of colored fibers in sediments is due to the domestic washing of clothes.

The highest values of filaments were observed at Firma and Kaa Assrasse beaches, where the overall averages were 27.33 ± 6.43 and 18 ± 7.21 filaments kg⁻¹, respectively, higher than the average for the study area. The primary activity commonly observed on the beaches of Firma and Kaa Assrasse is artisanal fishing, and numerous discarded fishing net fragments have been discovered on these beaches. The probable origin of these mesoplastics is the degradation of ropes, lines, and fishing nets. High densities of filament-type microplastics were also found on the beaches of Firma (184.67 ± 72.15 filaments kg⁻¹, ref. [39]) and Quaa Assrasse (74.67 ± 29.14 filaments kg⁻¹, ref. [40]). A greater proportion of these microplastics were transparent, confirming their origin from fishing activities. The high proportion of transparent mesoplastic filaments (55.83%) has been reported in numerous studies [33,69]. Other potential sources of filament mesoplastics may include maritime transport debris and urban runoff. Mitigation strategies could include proper disposal of fishing gear and targeted beach cleanups to prevent further accumulation.

The sites with the highest percentage of films on the Moroccan Mediterranean coast were Firma (10 ± 2 films kg⁻¹) and Martil (15.33 ± 13.01 films kg⁻¹). The majority of films observed in these areas presented irregular shapes (52% and 93%, respectively), suggesting that their source is related to the decomposition of large plastic items [87]. Tourist activities on the beaches of Firma and Martil may be responsible for the higher percentage of films, which could originate from the fragmentation of plastic items, such as plastic bags and packaging materials [84]. Other potential sources of films may include urban runoff carrying litter from surrounding areas. A significant concentration of mesofilms was found at Firma (5.33 ± 3.4 films kg⁻¹, ref. [39]) and Martil (7.3 ± 2.3 films kg⁻¹, ref. [40]), with a greater proportion of irregularly shaped (100% and 80%, respectively) and transparent films. Transparent films were prevalent and accounted for 35.66% of all films identified. The relatively high proportion of transparent films reflects advanced environmental degradation, as exposure to sunlight, saltwater, and mechanical abrasion gradually leads to color fading and increases transparency. These characteristics indicate a significant alteration of plastic waste along the studied area. Mitigation strategies could involve targeted beach cleanups, proper disposal of tourist waste, and public awareness campaigns to reduce plastic pollution.

In contrast to several studies [57,60,68,70,88], mesoplastic foams were poorly represented in the study area, and were only observed at eleven beaches, with an average density of 0.94 ± 1.83 foams kg⁻¹. A low abundance of foams was also reported for sandy beaches in the Liguria and Tyrrhenian seas [66,89], in the Gualí Cundinamarca wetland in Colombia [90] and in Malaysia [91]. The highest foam densities appeared on the beach of Beni Ensar (6.67 ± 11.55 foams kg⁻¹) located near the port of Beni Ensar. The beaches of Tangier Malabata (4 ± 6.93 foams kg⁻¹) and Martil (4 ± 2 foams kg⁻¹) also presented relatively large amounts of foams, mainly consisting of disposable cups, polystyrene packaging, and other beach-related items commonly associated with tourism. This pattern reflects the impact of tourism and inadequate beach waste management. The majority of foams on these three beaches were rather angular to subangular (90%, 33% and 83%). These findings align with previous studies on microplastic pollution along Morocco eastern [39] and northwestern [40] Mediterranean coasts, where foams were found on a few beaches only with average densities of 0.33 ± 0.83 foams kg⁻¹ and 1.1 ± 1.4 foams kg⁻¹, respectively. The dominant color of foams in the study area was white (76.62%), aligning with previous findings by Azaaouaj et al. (2025, 2024) [39,40] on the eastern and northwestern coasts of the Moroccan Mediterranean, where high concentrations of white microplastic foams were observed. This prevalence is not surprising, as white foams, particularly expanded polystyrene used in food packaging and disposable items, are among the most widely produced plastic materials.

Compared to other studies [78,92,93], pellets were poorly represented in the study area and they were only recorded at four beaches, with a low average density of 0.12 ± 0.35 pellets kg⁻¹. Previous studies have also reported low abundance of mesoplastic pellets on sandy beaches of the northeastern Tunisian coast [55], on the northeastern Levantine coast of Turkey [65], in the coastal waters of Tuscany in Italy [94], on beaches in central Italy [33], in Indonesia [95] and in Japan [96]. The low percentage of mesoplastic pellets (0.60%) recorded in this paper is consistent with the results obtained for pellet-type microplastics along the eastern (0.16%) and northwestern (1.30%) coasts of the Moroccan Mediterranean Sea [39,40]. The very low proportion of pellets observed was probably due to the lack of pellet sources (e.g., petrochemical and plastic production plants, etc.) along the studied coast and its hinterland. Industrial pellets were found in small quantities on the beaches of El Kaleth (17%), Cabo Negro (17%), Tangier Municipal (33%) and Tangier Malabata (33%) and were probably brought by marine currents [56,97]. The majority of pellets identified in the studied area were cylindrical (50%) and spherical (33.33%) in shape, which is in agreement with the results reported by Gündoğdu and Çevik [65]. As in many other studies [33,54,65,68,70], the most frequently observed pellet color was white (50%). All pellets found in the study area belonged to the 5–10 mm size class, which is normal since all industrial pellets are manufactured with a size < 6 mm [98].

The FTIR analysis identified nine types of polymers, namely polyethylene (PE, 24 items), polypropylene (PP, 14), polystyrene (PS, 9), polyvinyl chloride (PVC, 6), polyethylene terephthalate (PET, 3), styrene allyl alcohol (SAA, 1), polyurethane (PU, 1), polyamide (PA, 1), and styrene-butadiene copolymer (SBC, 1). The high density of polyethylene (PE) polymer found on beaches can be attributed to the fact that PE is the most widely produced and used polymer. Similar to the present paper, the sandy beaches of Iligan City, Philippines, were dominated with polyethylene mesoplastics (27.7%) [99]. Furthermore, a study by Scopetani et al. [59] yielded similar results, with polyethylene and polypropylene being the predominant polymers, accounting for 81% and 19%, respectively. Results from studies of beaches along the Latvian coastline (Northern Europe, Baltic States) showed that the majority of mesoplastics were identified as polyethylene (PE, 57.9%) and polypropylene (PP, 26.3%) [100]. The results of chemical analyses of microplastics collected from the beaches of the eastern Moroccan Mediterranean coast showed that the most frequent polymer found was PE [39].

Identified mesoplastic fragments, i.e., PE (20 items), PP (7), PS (5), PVC (3) and PET, (1) are widely used in industrial applications, clothing fabrics, fishery and aquaculture gear, detergent containers, and food packaging materials [39,98,101]. Mesoplastic films were identified as PP (4 items), PVC (3), PE (2), PET (1) and PA (1) polymers, which are commonly used in plastic wrapping and bags [52]. The pellets were identified as PE and SBC, with PE being the predominant component. This result is consistent with the findings of Abidli et al. [101], Arias et al. [102] and Azaaouaj et al. [39]. Filaments were identified as PP, consistent with the findings of Abidli et al. [101], Azaaouaj et al. [39] and Mohamed Nor and Obbard [52]. PP filaments are widely used in various products, including ropes, fishing nets, clothing fabrics, and diapers [39,52]. Mesoplastic foams were identified as consisting of PS, PET, SAA and PU, which are widely used in packaging products and floating buoys for fishing and aquaculture [39,103].

5. Conclusions

Plastic pollution is a serious problem that has long-term effects on the environment, particularly on marine ecosystems. This paper is the first report on mesoplastic pollution along the entire Moroccan Mediterranean coast and allowed basic information to be provided on the concentrations, characteristics and sources of mesoplastics along the study area. Mesoplastics were found on thirty-two of the thirty-three beaches studied and the average mesoplastic concentrations suggest a moderate degree of plastic pollution. The beaches of Firma and Beni Ensar, located on the eastern coast of the Moroccan Mediterranean, showed the highest amounts of mesoplastic items, mainly related to port activities, fishing and coastal tourism. The distribution of mesoplastics was variable among beaches and within the same beach. Fragments (43.92%) and fibrous mesoplastics (34.08%) were the main types, and most mesoplastic items were angular and irregularly shaped. Transparent (24.77%) and blue (21.72%) were the most common colors and more than 56% of the mesoplastics measured between 5 and 10 mm. The majority of mesoplastic polymers, obtained by means of FTIR analysis, consisted of PE, PP, PS and PVC. The moderate pollution of the Moroccan Mediterranean beaches by mesoplastics should not mask its severity, given the hazardous and persistent nature of this type of pollution. Furthermore, the nature of recollected mesoplastics, primarily of secondary origin, highlights the need to improve the actual inadequate and/or poor management practices of macroplastic litter pollution, especially linked to household activities but also coastal tourist and fishing activities. This study also provides valuable insights for improving environmental management and coastal protection. The data obtained can help environmental agencies and decision-makers identify high-risk areas, design more effective monitoring programs, and implement preventive measures to reduce plastic inputs at the source. Practical actions—such as targeted beach cleanups, improved waste management, and public awareness initiatives—could significantly reduce mesoplastic pollution along the Moroccan Mediterranean coast.