Table Of Content©
SociedadEspañola deMalacología /í^ét^í, 19 (2): 9-13, 2001
Seasonal infection dynamic of tetraphyllidean cestodes in
the ommastrephid squids from Galician waters
Dinámica estacional de la infección por cestodos tetrafilídeos en los
omastréfidos de aguas de Galicia
Santiago PASCUAL*
Recibidoel29-1-2001.Aceptadoel26-IV-2001
ABSTRACT
The seasonal dynamic of cestode tetraphyllidean infection by the genus Phyllobothrium on
the short-finned squids ///ex coindefii and Todaropsis eblanae from fishing grounds off
Galicia ¡s described. Seasonal changes in parasite infrapopulation counts were evident in
northern and southern fishing áreas but varying depending on host source. In any case
highest infection valúes were found in late winter at the time of large mature squids, whe-
reas lowest (and even no parasite recruitment to the host populations) infection valúes
were found in the summertime. This corresponding with abundant hatchings and paralar-
vae supported by peaks in upweiling and blooms in avoilable food related to the upweiled
Eastern North-Atlantic Central Water (ENACW).
RESU/V\EN
Este trabajo describe la dinámica estacional de las infecciones por cestodos tetrafilídeos
del género Phyllobothrium en las potas ///ex coindefiiy Todaropsis eblanae capturadas en
las áreas de pesca de Galicia. Se evidenciaron cambios estacionales en el número de las
infrapoblaciones parásitas en las áreas de pesca del norte y del sur, aunque éstos varia-
ron en función de la especie hospedadora. En cualquier caso, los niveles más altos de
infección se produjeron al final del invierno coincidiendo con las potas grandes y madu-
ras. Mientras, los valores más bajos de infección (incluso sin reclutamiento de los parási-
tos en las poblaciones hospedadoras), se encontraron en el verano, coincidiendo con el
periodo de puesta y abundancia de paralarvas, relacionada con los picos de aflora-
mientoy disponibilidad de alimento en la masa de Agua Central NorAtlántica (ACNA).
KEYWORDS: cestode, tetraphyllidean, Phyllobothrium, Illexcoindetü, Todaropsiseblanae.
PALABRASCLAVE: cestodo, tetrafilídeo, Phyllobothrium, Illexcoindetü, Todaropsiseblanae.
INTRODUCTION
Despite symbiotic relationships plerocercoid stages. This lack of infor-
between adult tetraphyllidean cestodes mation is especially evidentwith regard
and their elasmobranch final hosts have to the cephalopod hosts, in spite of the
been largely studied, little work has fact that tetraphyllidean larvae have
been done on the larval procercoid and been recovered and taxonomically iden-
* Laboratorio de Parasitología, Grupo PB2, Facultadde Ciencias del Mar, UniversidaddeVigo, Aptdo. 874,
36200,Vigo,España. E-mail: [email protected]
Iberus, 19 (2), 2001
Figure 1.ThelocationofsamplingzonesofFGalicianwaters (NWSpain).
Figura 1. Localizacióndelaszonasdemuestreoenlascostasgallegas (NOEspaña).
tified from a wide diversity of coastal, lez, Rasero and Guerra, 1996), thus
neritic and/or oceanic squid, cuttlefish providing an opportunity to describe
and octopus species worldwide (see the seasonal infrapopulationbehaviorof
review by Hochberg, 1990). Among the plerocercoid tetraphyllideans in
this, only a few studies by Canadian, commercially-important ommastrephid
Russian and Spanish researchers (e.g., squidpopulations.
Brown and Threlfall, 1968; Bower,
Margolis and Yang, 1990; Nigmatu-
LLiN AND Shukhgalter, 1990; Pascual, MATERIALAND METHODS
González, Arias and Guerra, 1995a;
Pascual, Rasero, Arias and Guerra, At monthly intervals between 1992-
1995b)have dealtwith the demographic 1993, 1200 post-recruit of lesser flying
infection valúes and/or host-parasite squids Ulex coindetü (Vérany, 1839) and
relationships, but neither study provi- broadtailed short-finned squids Todarop-
ded a detailed account of the seasonal sis eblanae (Ball, 1841) (600 each) were
population dynamics of the infection in collected by fishermen from local
the wild, though this may be essential fishing grounds offGalicia (42° 5' to 45°
for a better understanding of the para- 15' N, 7° to 9° 20' W) (Fig. 1). Samples
site recruitment and their ecological comprising 25 individuáis per host
impact on wildlife cephalopod popula- species and sampling área were obtai-
tions(Pascual, 1996). ned from commercial landings in
In températe waters off the NE several ports within two hydrographi-
Atlantic, relatively large ommastrephid cally well-differentiated áreas (Fraga,
samples were routinely available for MouRiÑo and Manri'quez, 1982). The
study in commercial fisheries (Gonzá- northern group consisted of all squids
10
Pascual: Seasonal infection dynamic ofcestodes in squids from Galicia
25 750
- 500
20
- 250
15
-o
c O o
10
-250
5 -
-500
-750
-T 1 1 p ^ 1 1 1 1 1 1 r-
J F, M A My Jn Jl Au S Oc N D
t !
Mature Inmature Submature
Figure 2. Monthlyvalúes in abundance ofinfection by Phyllobothriumspp. in squid at both sam-
O
pling áreas. (• ICN, Illexcoindetüfrom the northern área; ICS, /. coindetüfrom the southern
área; I TEN, Todaropsis eblanaefrom the northern área; TES, T. eblanaefrom the southern
área). Mature, immatureandsubmaturesquids (i.e., conditionofthegonad) wasassessedusingan
universal maturity scale (LiPINSKY, 1979). The histogram represents the upwelling index (UI,
expressedasm3s-lKm-l).
Figura2. ValoresmediosdeinfecciónporPhyllobothriumspp. encalamaresdeambasáreasdemuestreo.
O
(% ICN, Illexcoindetü deláreanorte; ICS, I. coindetü deláreasur; TEN,Todaropsiseblanae
delárea norte; TES, T eblanae deláreasur). La condición delagónadadeloscalamares (maduro,
inmaduroysubmaduro)seajusto usando una escala universaldemadurez (LiPINSKY, 1979). Elhisto-
gramarepresentaelíndicedeafloramiento (UI, expressedasm3s-lKm-l).
collected fromBurela to Finisterre (ICES the most appropriate demographic
división VIIIc) and the southern group infectionvaluéduetoitspopulationsig-
consisted of squids caught from Finiste- nificance (BusH, Lafferty, Lotz and
rre to Miño river (ICES división IXa). Shostak, 1997).
Each month, the viscera was removed
fromfreshdead squid and examined for
larvaltetraphyllideancestodes. Seasonal RESULTS
differences among log-transformed
parasite infrapopulation counts were Inthe northern área, a clear seasonal
compared using one-way ANOVA. To patternofplerocercoid infectionby Phy-
this end, data were analyzed on a quar- llobothrium vanBeneden, 1850 larvae in
terly basis: winter (January-March), both squid populations (F= 23.56; p<
spring (April-June), summer (July-Sep- 0.001 for7. coindetü) (F=4.885; p<0.05for
tember) and autumn (October-Decem- T. eblanae) was observed (Fig. 2). Abun-
ber). The abundance of infection dance ofinfectionincreased throughout
(defined as thenumberofindividuáis of the winter, reaching a máximum in late
a parasite species in a host species winter and early spring at the time of
regardless of whether or not the host is spawning. The highest infection valúes
infected) was calculated each month for were found inthe largest mature squids
both host species and fishing áreas as butdecliningtowardsthesummer,when
11
Iberus, 19 (2), 2001
immature individuáis are abundant. In FALL 1970; Gaevskaya and Nigmatu-
the Southern área, a significant seasonal llin 1981; Nigmatullin and Shukh-
variation was only found in the short- GALTER 1990; Pascual et al., 1995a, b).
finned squid /. coindetii (F= 5.89; p<0.05). Nevertheless, the abundance of infec-
By the contrast, no seasonal variation in tion did not increase with host maturity
infection valúes (F= 0.289; p=0.602) was in the squids from the southern group
evident in T. ehlanae. Nevertheless, the which may be due to a lower overdis-
general pattern of seasonal parasite persion pattern of parasite infrapopula-
dynamicclearlysuggeststhatinfectionis tions than it accounted in the northern
higherduringcoldermonthsthanduring group. The effect of accumulation factor
warmermonthswhichisinverselycorre- resulting fromfeedingpatternshasbeen
lated with the upwelling index, regard- previously described in other trophi-
lessofhostsourceorsamplingárea. cally-transmitted cephalopod parasites
by Pascual, González, Arias and
Guerra (1999).
DISCUSSION Otherwise, it is important to note
that seasonal behavior of infection he-
According with Hochberg (1990), rein reported reflect variation in hydro-
plerocercoids of Phyllobothrium spp. in graphically-distinct sampling local áreas
teuthoid cephalopods exhibit a marked of a single host species. In fact, regional
ecological-specificity, i.e., they are more variations (north-south) in the composi-
dependentontrophiclevéisoccupiedby tion ofthehelminth fauna ofboth squid
the host species than on host phylogeny species has been also previously noted
per se. The highest valúes of cestode in- by Pascual et al. (1996). Despite the
frapopulation counts during squid short distance between both sampling
spawningtime herein reported, suggest áreas, these regions exhibit differences
that many species of selachians feed on in oceanography, biological producti-
the fast-moving squids mainly during vity, fauna composition, and diversity
the massive die-offs that occur follo- which may explain differences in infec-
wing spawning. This clearly represents tions valúes to the northern and sout-
a synchronization of parasite and squid hern mature squids. This clearly indica-
life-history strategies, inwhich the para- tes that long-term sampling surveys
site utilizes the optimal stage of ontogé- should be carried out when comparing
nesis (i.e., trophiclevel)ofthehosttoin- infection patterns in cephalopod popu-
sure the máximum probability of entry lations, even at a microgeographic scale.
into the final host. This pattern was also Results also suggests that despite the in-
suggestedby Nigmatullinand Shukh- fluenceofabioticfactorswhichcould af-
GALTER (1990) in the Patagonian squid fecttheinfectivefree-livingparasiticsta-
Illexargentinus from45-47"Sbutthey ob- ges and thus their seasonalbehavior, re-
served no seasonal fluctuations among cruitment of worms to squid
intraspecific groupings of similar size populations doesnotappeartobe conti-
and maturity. In this way, the bimodal nuous. Infections were thus less abun-
pattern of seasonal infection (highest dant during late spring and summer,
during winter to springtime and lowest which coincided with the periodicity of
during summertime) herein reported, host spawning for both squid species
may be due to variations in squid size, (González and Guerra, 1996) where
age and/or maturity and ultimately to hatchings and paralarvae are supported
host feeding habits (Pascual, Gonzá- by peaks in upwelling and blooms in
lez, Arias and Guerra, 1996). In fact, available food related to the upwelled
the abundance ofinfection clearly incre- Eastern North-Atlantic Central Water
ased with increasing host maturity over (ENACW) (Rocha, Güera, Prego and
the entire life cycle, a characteristic com- PiATKOWSKi, 1999). This type of periodi-
mon to many ommastrephid squids city appear similar to that described r-
(Brown and Threlfall, 1968; Threl- strategist organisms which have well-
Pascual: Seasonal infection dynamic ofcestodes in squids from Galicia
defined seasonal cycles in températe lician waters. Additionally, a wide dis-
waters oftheworld. Therefore, anecolo- tribution ofboth host and parasite cle-
gical specificity based on host-related arly show the potential cosmopolitan
bioticfactorsratherthananoceanograp- characterofthe infectionand theimpor-
hic or host specificity is likely to be the tant role played by large, mature om-
caused of seasonal infection dynamic of mastrephids as second intermediate
tetraphyllidean cestodes of Phx/Uoboth- hosts for Phyllobothrium in températe
rium intheshort-finned squidsfromGa- watersofftheNEAtlantic.
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