International Journal of Marine Science 2016, Vol.6, No.37, 1-5
1
Research Report Open Access
Fluctuating Asymmetry in the Otolith of two Parrotfish Species,
Chlorurus
sordidus
(Forsskål, 1775) and
Hipposcarus harid
(Forsskål, 1775) from
Hurghada, Red Sea coast of Egypt
Mohamed Abu El-Regal
1
, Laith Jawad
2,
, Sahar Mehanna
3
, Yassin Ahmad
4
1. Department of Marine Science, Faculty of Science, Port Said University, Port Said, Egypt
2. Flat Bush, Manukau, Auckland, New Zealand
3. Laboratory of Population Dynamics, Fisheries Division, National Institute of Oceanography and Fisheries, Suez Branch, Suez, Egypt
4. Laboratory of Population Dynamics, Fisheries Division, National Institute of Oceanography and Fisheries, Red Sea Branch, Hurghada, Egypt
Corresponding author email
International Journal of Marine Science
2016, Vol.6, No.37 doi
Received: 24 Aug., 2016
Accepted: 10 Oct., 2016
Published: 11 Oct., 2016
This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and
reproduction in any medium, provided the original work is properly cited.
Preferred citation for this article
:
El-Regal M.A., Jawad L., Mehanna S., Ahmad Y., 2016, Fluctuating Asymmetry in the Otolith of two Parrotfish Species,
Chlorurus sordidus
(Forsskål, 1775)
and
Hipposcarus harid
(Forsskål, 1775) from Hurghada, Red Sea coast of Egypt, International Journal of Marine Science, 6(37): 1-5 (doi:
Abstract
Fluctuating asymmetry was calculated for the otolith length and width of the adult fishes
Chlorurus sordidus
and
Hipposcarus harid
. The results showed that the level of asymmetry of the otolith length was the higher than that of the otolith width
in both species. For
C. sordidus
, the lowest level of asymmetry in the otolith length was at the fish total length ranging between
150-260 mm, and the highest at the fish total length 160-260 mm. For the otolith width, the highest level of asymmetry is at the fish
length ranging between 24-26 mm and it has zero value in the other length groups. For
H. harid
, the lowest level of asymmetry in the
otolith length was at the fish length ranging between 160-170 mm, and the highest at the fish length 240-260 mm. For the otolith
width, the highest level of asymmetry is at the fish length ranging between 240-260 mm and it has zero value in the other length
groups. The possible cause of the asymmetry in these species has been discussed in relation to the general presence of pollutants in
the area. An increasing asymmetry with the fish length (age) was noticed.
Keywords
Otolith; Dimensions; Bilateral asymmetry; Scaridae; Ecological indicator
Introduction
Fluctuating asymmetry is a differential development of a bilateral character between the sides of an organism (Van
Vallen, 1962; Leary and Allendroff, 1989). Developmental instability can be reflected by fluctuating asymmetry
which is a random deviation from perfect bilateral system. In another words, it is the inability of an organism to
compensate for disturbances during development (Zakharov, 1992), and such incapability can be affected by stress
related to environmental or genetic conditions. As a result, high fluctuating asymmetry could indicate the worst
condition of fish that experience unfavourable environments. Therefore, the bilateral asymmetry measure could
show an environmental influence on the fitness of the organism.
Several adult fish species were used to study the relationship between fish condition and fluctuating asymmetry. In
such a studies, numbers of measurements have been proposed, including the number of gill arks, pectoral fin rays,
fish body proportions, eye spot area, or otolith size and shape (Escós et al., 1995; Somarakis et al., 1997; Jawad,
2001, 2003, 2004; Gonçalves et al., 2002; Jawad et al., 2012).
In having an asymmetrical otolith, fish will face some consequences that might change its habit or behaviour
(Gagliano et al., 2007; Gagliano and McCormick, 2004). The survival of young individuals will be threatened as it
will be difficult for them to find a proper place for settlement. On the other hand, fluctuating asymmetry in the otolith
would be of interest to fisheries managers as it can supply a sort of measurement of past individual and population
fitness due to the possibility to study otolith of specimens from old populations. Such information will assist in the
collapse of a present time stock and throws light on the future management strategies (Díaz-Gil et al., 2015).
