Research Article | Volume 4 - Issue 1 | Article DOI :
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Majda Aouititen1*, Ratiba Bekkali1, Driss Nachit1 and Mohammed Mrhraout2
1Laboratory of Environment, Biodiversity and Ecology, Abdelmalek Essaadi University, Morocco
2National Institute of Fisheries Research Tangier-M’Diq, Morocco
Corresponding Author:
Majda AOUITITEN, Laboratory of Environment, Biodiversity and Ecology, Faculty of Sciences, Abdelmalek Essaadi University, BP. 2121 M’HannechII, 93030 Tetouan, Morocco, Tel: +212623264959
Keywords
Pelagia noctiluca; Jellyfish; Stranding; Morocco; Mediterranean north-west coastline
Abstract
In the recent years, the frequency and the geographic distribution of jellyfish blooms have been increased in the Mediterranean north-west coastline of Morocco, since 2011 this area has been subjected to successive blooms and stranding of Pelagia noctiluca; our research was aimed to study the causes of jellyfish blooms and stranding in our coastline. We have evaluated three parameters that we are suspecting to be responsible of Jellyfish stranding on the northern coast of the Mediterranean Sea in Morocco. The evaluation of the relations between sea surface temperature, waves height and the wind direction causing the stranding of Jellyfish, demonstrated that the correlation scores was found to be statistically significant with r(33) =0.445, p < 0.01, for sea surface temperature (°C) and r(33) =0. 694, p
Citation
Aouititen M, Bekkali R, Nachit D and Mrhraout M. Jellyfish Stranding in the Moroccan North-West Mediterranean Coastline. SM J Biol. 2018; 4(1): 1019.
Introduction
Jellyfish stranding one of the most important, and complicated topics that scientists all over the world are try to understand. Obviously, Jellyfish spatiotemporal dynamics are highly variable, as well blooms occur irregularly are difficult to predict [1,2]. Pelagia noctiluca (Forsskål 1775) most common jellyfish species in the Mediterranean waters, it is widely distributed from the warm subtropical waters of the Gulf of Mexico and the Mediterranean Sea to the temperate waters of the North Sea [3-6] and up to 4°C of latitude [7,8].
Pelagia noctiluca is an important non selective planktonic predator [9-13] feeding on almost all types of zooplankton and ichthyoplankton [14,15] in fact, Many fish compete for the same zooplankton prey as jellyfish [15], moreover fish are also predators of jellyfish, with benthic including reef fish species ingesting polyps, as well as pelagic fish species eating ephyrae and small individuals [16]. However, the declination of such fish opens up ecological space for jellyfish proliferations. Moreover, Coastal eutrophications encourage phytoplankton blooms that can ultimately lead to jellyfish outbreaks [17]. The greater tolerance of polyps and medusa than fish to low-oxygen conditions ensures that jellyfish survive, even reproduce during hypoxic events, which fish are unable to do, such ‘dead zones’ are thought to favor jellyfish [18]. Warmer temperatures also accelerate medusa growth and ephyrae production [19]. Jellyfish appear to be sensitive to climate variability, with their abundance being related to large-scale climate indices such as the North Atlantic Oscillation (NAO) [18], El Nino Southern Oscillation [19] and the Pacific Decadal Oscillation [20].
Material and Methods
Study area
M’Diq Having as geographical coordinates 35° 41’N 5° 19 ‘31 W, is a seaside resort the population lives almost exclusively on fishing and summer tourism activities, it hosts more than 100,000 tourists each year. M’Diq is located 7 km from Tetouan city, and it’s bounded on the north by Fnideq municipality, on the south by Mallaliyine commune, on the west by Alleyine commune and on the east by the Mediterranean Sea. M’Diq covers areas of 480 hectares of which 153 hectares are urbanized (Figure 1). The selection of this area is based on the presence of jellyfish blooms along the beaches.

Figure 1: Geographical location of M’Diq beach our study area in the Mediterranean coastline of Morocco Google Map.
Sampling strategy
Jellyfish survey strategy used for our study was inspired of the method used by Doyle [8] for the study of jellyfish species repartition across the Irish and Celtic Sea shores. We were used to Cross daily M’Diq coastline area, while counting stranded Jellyfish species. We did use the Quadrate method to calculate the density of jellyfish stranded per square meter. The study was conducted during Jun 2011 to December 2017 (Table 1 and Figure 2).
Table 1: Scientific classification of study sample of Jellyfish.
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Kingdom:
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Animalia
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Phylum:
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Cnidaria
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Class:
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Scyphozoa
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Order:
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Semaeostomeae
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Family:
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Pelagiidae
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Genus:
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Pelagia
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Species:
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P. noctiluca
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Binomial name
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Pelagia noctiluca
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(Forsskål, 1775)
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Synonyms
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Medusa noctiluca Forsskål, 1775
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Pelagia perla (Slabber, 1781)
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Figure 2: Pelagia noctiluca sample (source AOUITITEN).
Jellyfish identification & environmental variables
Pelagia noctiluca is the only jellyfish species was found stranded in the Mediterranean north-west coastline of Morocco. We have used Russell taxonomic for the identification of the stranding jellyfish. Sea surface Temperature was recorded in situ (independent points) for each survey. In addition measures of waves height and wind direction was obtained from PREVIMER web-sites. These parameters recorded for every day of the six years were used for correlation analyses to find if they are causing Jellyfish stranding.
Cluster analysis
Part of the data obtained from the samples was statistically calculated, analyzed using Microsoft Excel software. However Pearson Correlation analysis were used to determine whether there is relationship between our quantitative variables which are sea surface temperature, waves height and Jellyfish stranding, as well as ANOVA test were used to determine if there is a relationship between our quantitative variable wind direction with Density of jellyfish stranded, this tow test were statistically calculated, analyzed and compared using SPSS software.
Results and Discussion
Physical parameters of water
Analysis of the samples of water in our zone of study has yielded several physical and chemical characteristics of the environment where Pelagia noctiluca stranded. Physical water measures including the temperature shows that the appearance of the jellyfish Pelagia noctiluca starts in our coastline at a sea surface temperature of 21°C, the maximum abundance is reached at a sea surface temperature of 25.61°C, then P. noctiluca start to disappear at a sea surface temperature of 16 °C, moreover we have observed that when the waves have the height between 1.20m to 2m, we have probably appearance of Pelagia noctiluca (Figure 3).

Figure 3: Monthly variation of (SST) sea surface temperature (°C), Waves height (m) and the density of jellyfish stranded per m² (from 2011 until 2017).
Wind direction
We have observed that when the east wind blows on our beaches, we have probably appearance of Pelagia noctiluca and if it’s not, we will not found any jellyfish even if the sea surface temperature is high enough to have stranded jellyfish (Figure 4).

Figure 4: Satellite-derived sea-surface significant wave’s height and wind direction (model WAVEWATCH III following Douglas Sea and swell scale protocol, 1921). Instrument for the stranding months from June 2011 to December 2017.
Statistic analysis
Statistical analysis was carried out using statistical tests software package, with the intention of studying the relation between sea surface temperature, sea waves height and Jellyfish stranding. To determine whether there is relationship or not a Pearson Correlation test shows that the density of jellyfish stranded and Sea waves height have a statistically significant linear relationship r(33) = 0.445, p < 0.01 (Table 2), meaning that these variables tend to increase together (greater Density of jellyfish stranded is associated with greater Sea waves height). Moreover we have found that the relationship between the Density of jellyfish stranded and Sea waves height was a positive correlation between the two variables, r = +0.694, n = 33, p = 0.001 (Table 3).
Table 2: Relation of correlation between sea surface Temperature and the density of Pelagia noctiluca stranded.
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|
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Density of jellyfish
stranded per m²
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Sea Surface
Temperature (°C)
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Density of jellyfish stranded per m²
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Pearson Correlation
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1
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0.445**
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Sig. (2-tailed)
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0.01
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N
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33
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33
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Sea Surface Temperature (°C)
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Pearson Correlation
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0.445**
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1
|
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Sig. (2-tailed)
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0.01
|
|
|
N
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33
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33
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**Correlation is significant at the 0.01 level (2-tailed).
Table 3: Relation of correlation between sea wave’s height and the density of Pelagia noctiluca stranded.
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|
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Density of jellyfish
stranded per m²
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Sea waves
height (m)
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|
Density of jellyfish stranded per m²
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Pearson
Correlation
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1
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0.694**
|
|
Sig. (2-tailed)
|
|
0
|
|
N
|
33
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33
|
|
Sea waves height (m)
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Pearson
Correlation
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0.694**
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1
|
|
Sig. (2-tailed)
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0
|
|
|
N
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33
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33
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**Correlation is significant at the 0.01 level (2-tailed).
A one-way analysis of variance (ANOVA) was calculated on wind direction causing stranding of jellyfish. The analysis was significant, F (1, 31) = 25.823, p = 0.001 (Tables 4 and 5). East wind cause the stranding of jellyfish (M = 26.70, SD = 16.463) more than the West wind (M = 0.00, SD = 0.000).
Table 4: Descriptive Relation between wind direction and the density of Pelagia noctiluca stranded.
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95% Confidence
Interval for Mean
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|
|
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N
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Mean
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Std.
Deviation
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Std.
Error
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Lower
Bound
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Upper
Bound
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Minimum
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Maximum
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East
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23
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26.7
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16.463
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3.433
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19.58
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33.81
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6
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60
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West
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10
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0
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0
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0
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0
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0
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0
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0
|
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Total
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33
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18.61
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18.481
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3.217
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12.05
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25.16
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0
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60
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Density of jellyfish stranded per m²
Table 5: ANOVA test to determine the relationship between wind direction and the density of Pelagia noctiluca stranded.
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Sum of Squares
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df
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Mean Square
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F
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Sig.
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Between Groups
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4967.009
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1
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4967.009
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25.823
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0
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Within Groups
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5962.87
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31
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192.351
|
|
|
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Total
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10929.88
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32
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Density of jellyfish stranded per m²
Conclusion
The greater sea surface temperature, important waves height and east wind direction are the three parameters causing the stranding of the Jellyfish Pelagia noctiluca in our zone of research, the correlation scores for all the parameters was found to be statistically significant with r(33) = 0.445, p <0.01, for sea surface temperature (°C) and r(33) = 0. 694, p < 0.001 for waves height (m) as well as a one-way analysis of variance (ANOVA) was calculated on wind direction found to be very significant, F (1, 31) = 25.823, p = 0.001.
Acknowledgment
The authors would like to thank M’diq station of the National Institute of Fisheries Research (INRH) for its infrastructural and moral support and the anonymous reviewers for their comments on the draft of this manuscript. M. A. has received a Ph.D. grant from “the Ministry of National Education, Higher Education and Research of Morocco”.
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