Biodiversity of Parasitic Copepods in Katsuwonus pelamis from Rio Grande do Norte Coast (NE Brazil)
Cláudio Giovanio da Silva2*, Erivaldo Laurindo Gomes1, Naibe Cristina de Figueiredo1 and José Ticiano Arruda Ximenes de Lima3
1Centro de Ciências Agrárias, Universidade Federal Rural do Semi-Árido, Brasil
2Laboratório de Sanidade Aquática, Universidade Federal Rural do Semi-Árido, Brasil
3Centro de Ciências Agrárias. Universidade Federal Rural do Semi-Árido, Brasil
Submission: February 06, 2018; Published: September 26, 2018
*Correspondence author: Cláudio Giovanio da Silva, Laboratório de Sanidade Aquática, Centro de Ciências Agrárias, Universidade Federal Rural do Semi-Árido, Rio Grande do Norte, Brasil.
How to cite this article: Cláudio G d S, Erivaldo L G, Naibe C d F, José T A X d L. Biodiversity of Parasitic Copepods in Katsuwonus pelamis from Rio Grande do Norte Coast (NE Brazil). Oceanogr Fish Open Access J. 2018; 8(3): 555739. DOI:10.19080/OFOAJ.2018.08.555739
Ictioparasitology is a science that has, among its objectives, assisted in the understanding of the interactions between fish and their parasites. Crustaceans are one of the most popular invertebrate groups exhibit a striking diversity of forms, habits and sizes, are found at all depths in the various marine and freshwater of the earth, and Copepod class are the largest group crustacean parasites in fish, with economic importance, which may result in high mortality. In the present work the biodiversity of the parasitic copepods of skipjack tuna (Katsuwonus pelamis) from the Southwest Atlantic Ocean - Rio Grande do Norte, Brazil, is reported. Parasitic ecological indexes (prevalence, mean intensity and mean abundance) were also calculated. Fish were collected in the coastal area of Areia Branca (state of Rio Grande do Norte) from 2015 to 2016. Standard biometrics of the hosts was also taken. Four species were identified infecting branchial chamber and body skin of K. pelamis.: Caligus pelamydis (17.65%), C. bonito (36.27%), C. productus (37.25%) and Pseudocycnus appendiculatus (8.82%).
The ictioparasitology is a science that has, among its objectives, assisted in the understanding of the interactions between fish and their parasites. The parasitism is the most common style of life on earth, as there are numerous representatives of permanent or temporarily zoological groups involved in interspecific relationship [1,2].
With regard to marine environments, Luque  considers that the knowledge about the diversity of species of parasites is still incipient front of the large ichthyological diversity. According to Pavanelli and Takemoto  the parasite identification studies are important to know possible pathologies occurring in their hosts. Usually the damage to the host by parasitic diseases is related to the parasite species, its form of feeding, organ or tissue of an affected host, parasitism intensity and general condition of the host [5,6].
The crustaceans are one of the most popular invertebrate groups exhibit a striking diversity of forms, habits and sizes, are found at all depths in the various marine and freshwater of the earth . The parasitic crustaceans are highly modified organisms and oral swimming appendages have turned into powerful fasteners to the host, with consequent repercussions pathogenic
. The main groups comprising fish parasites are Copepods, Branchiura and Isopoda .
Copepods are the largest group crustacean parasites in fish, with more than 1,900 known species. Many species have economic importance especially when parasitize cultured fish, which may result in high mortality. All copepods have a post-embryonic development that usually goes through three stages: nauplius, copepodite and adult .
The skipjack tuna Katsuwonus pelamis (Linnaeus, 1758; Osteichthyes: Scombridae) is an opportunistic predator that inhabits the tropical and warm temperate waters of all oceans. The range of this fish in the Atlantic Ocean is from 40 °N to 32 °S, from the surface to about 260m depth. Its distribution is influenced by water temperature (optimum range from 15 to 30 °C). The skipjack tuna spawns when the surface temperature is ≥24 °C, and its spawning season varies according to locality . This study aimed to evaluate the parasites copepods biodiversity in the host skipjack tuna (K. pelamis) from the Southwest Atlantic Ocean - Rio Grande do Norte, Brazil.
Located in the northeast of Brazil, the coastal region of Rio Grande do Norte (Figure 1) has humid tropical climate hot, with rains in the Summer (December to March) and dry conditions in Spring, Winter and Autumn (April to November), with an annual mean of 823mm of rain and 32 °C air temperature . The fish
were acquired from fishermen in coastal area of Areia Branca, state
of Rio Grande do Norte. Catches fish were carried out between the
months of December/2015 to November/2016. The fish samples
were carried out with the help fishermen in the region.
All fish were packaged in individual bags and stored in thermal
boxes (with ice) for transport to the laboratory, where they were
subjected to meristic and morphometric analysis, registering
mainly the total weight (WT, in grams) and the length fork (LF, in
millimeter) and the species was confirmed and sexed according
Vazzoler . After capturing in study area and the realization
of biometrics, the fish were necropsied to perform the parasitic
The collecting of the parasitic fauna was carried out according
to each specimen found, following the recommendations of Eiras
et al. , where the gills of the fish were removed and distributed
into vials with formalin 1: 4,000; After resting for an hour in
solution, the vials were shaken vigorously and the contents
resuspended in 5% formalin; The gill filaments were carefully
shaved with scalpel blades for the removal of parasites present;
The integument regions of the body, nasal cavities, mouth were
analyzed; The collected specimens were stored in 70% alcohol.
After initial procedures, copepods fixed in alcohol 70% were
counted. The parasitic ecological indexes were calculated and
expressed as Bush et al.  and Silva et al. .
Prevalence was determined using the equation of the
ratio between the number of hosts infected with one or more
individuals of a taxonomic group and the number of hosts
examined, expressed by the relation:
Mean Intensity was determined using the equation of the
relationship between the total number of parasites a taxonomic
group and number of host species infected with those parasites,
expressed by the relationship:
Mean Abundance was determined using the equation of the
relationship between the total number of parasites a taxonomic
group, and the total number of hosts examined (infected and
uninfected), expressed by the relation:
The parasite species were identified with proposed taxonomic
identification keys for the study group. To verify a possible
influence of sex and length of the hosts on parasitic prevalence,
was carried out analysis Student’s t-test at 5% significance
They were acquired hundred and two fish (n = 102) skipjack
tuna (Katsuwonus pelamis) between the sampling months
(December/2015 to November/2016), presented values
biometric these according to Table 1. Among those acquired fish,
it was observed was a predominance of males in the months in
study, 54 were males and 48 females.
The species copepods parasites were determined using
proposed taxonomic identification keys for these species, were
identified from their morphological characteristics as Caligus
pelamydis (Kroyer, 1863) and C. bonito (Wilson, 1905) parasitizing/
located on the branchial chamber and body skin of the host; C.
productus (Dana, 1852) and Pseudocycnus appendiculatus (Heller,
1865) parasitizing branchial chamber the host. Ecological indexes
of these species infesting skipjack tuna are shown in Table 2. No
significant differences were encountered (P>0.05) of parasitic
prevalence between the sexes and sizes of hosts, i.e. there was no
significant relationship between these variables.
This study reports the biodiversity and occurrence of parasites
copepods parasitizing skipjack tuna (Katsuwonus pelamis) of Rio
Grande do Norte coast, northeastern Brazil. According to Carvalho
& Luque  studies in naturally infected hosts are important for
the understanding of population indicators and registration of
new hosts and new geographical areas of parasitic species.
In northeastern Brazil, the first record of parasites copepods
was made by Schubert in 1936. Subsequently, other researchers
have been conducting records of parasite copepods in this region,
as Cavalcanti et al.  which identified Caligus bonito and Caligus
sp. in tainha (Mugil curema) in waters this same region of this
The copepods were found in the branchial chambers and
integument and can also be located in your nostrils and oral
cavity according to other researchers. Parasitic shapes can be
constituted up of adults (observed in this work) and some larvae
forms, and may be fixed through more or less complex fixation
organs, or have some ability to move the surface of the host. The
presence of copepods is more or less visible because of the size
that can be achieved, or the presence of ovigerous bags whose
color often contrasts with the integument of the host, allowing its
Of the species found in this study, Caligus pelamydis, C. bonito,
C. productus and Pseudocycnus appendiculatus had previously
been cited for this host. Alves et al.  in Brazil described this
species in Rio de Janeiro & Mele et al.  described these species
in skipjack tuna from the western Mediterranean Sea.
The high prevalence of copepods in the analyzed host is
common in natural environment, not only to skipjack tuna, but
also for other species of fish. According Schalch  in habitat in
which there is constancy in temperature of the water as water
in the Northeast, the seasonal variations of parasitism are not
significant. The ecological index of P. appendiculatus(P%=8.82) in skipjack tuna are down to other works with the same fish that
this parasite infested, the prevalence of these ranged from 13 to
13.3%. The C. pelamydis (P%=17.65), C. bonito (P%=36.27) and C.
productus (P%=37.25) are in the same range compared to other
work in host K. pelamis, the prevalence of these ranged from 13.3
to 80% [10,16].
Parasitic infections can retard the growth and host weight
gain of the fish when they affect food intake . Statistical
analysis of the study showed no significant relationship between
the ecological indices and the length and weight of the host.
Bullard et al.  mentioned that the behavior of forming
shoals facilitates the horizontal dispersion of the larvae of
copepods in some species of fish, corroborating with the ecological
parameters of the genus Caligus, pointing out that this behavioral
fact, in the present work with skipjack tuna (K. Pelamis), influenced
the horizontal transmission of parasite species in study. According
Appeltans et al.  various studies have been conducted over the
years to determine the diversity and relative effect of parasitism
in the world. However, there is little information on the parasites
in skipjack tuna and other species off the coast of Rio Grande do
This work made the taxonomic identification of parasitic
copepods and recorded the occurrence of Caligus pelamydis, C.
bonito, C. productus and Pseudocycnus appendiculatus in host-fish
Katsuwonus pelamis caught in the Rio Grande do Norte coast. The
prevalence of the three parasitic species Caligus (C. pelamydis:
P%=17.65) (C. bonito: P%=36.27) (C. productus: P%=37.25) were
considered normal in relation to other works with the same host
under study and P. appendiculatus (P%=8.82) was considered
low. Location of infestation was the branchial chamber and body
skin the host. Compared to other authors study copepods in Rio
Grande do Norte, this host-parasite fish presented a diverse flora.
Thanks to Marcia Avelino Coelho for auditing the study.
To CNPq (Conselho Nacional de Desenvolvimento Científico e
Tecnológico) and CAPES (Coordenação de Aperfeiçoamento de
Pessoal de Nível Superior) for financial support granted to postgraduation
and graduation programs, and to the UFERSA for
technical and scientific support.