Parasitological survey of coastal birds from the Magellanic coast, Southwestern Atlantic Ocean

Abstract Ecto and endoparasites of four species of coastal birds, Haematopus ater, Larus dominicanus, Leucophaeus scoresbii (Charadriiformes), and Lophonetta specularioides (Anseriformes), are reported from Puerto Deseado on the Patagonian coast, Argentina. Only H. ater was infested with lice (Phthiraptera), belonging to 2 species (Ischnocera, Amblycera). A total of 19 helminth species were found parasitizing the coastal birds studied: 4 cestodes (1 Tetrabothriidae, 3 Cyclophyllidea); 11 trematodes (2 Gymnophallidae, 3 Microphallidae, 2 Notocotylidae, 1 Philophthalmidae, 2 Renicolidae, 1 Schistosomatidae); 3 nematodes (1 Anisakidae, 2 Acuariidae); and 1 acanthocephalan (Polymorphidae). Although some isolated records have been previously reported for these birds, the present work provides a parasitofauna study for H. ater, L. scoresbii, and L. specularioides for the first time. Endoparasites reflected the feeding habits of the birds; the parasite assemblage of L. dominicanus was the richest, indicating their wide prey spectrum and the diversity of the habitats frequented. A great species richness of trematodes, whose life cycles are partially known, suggests that L. specularioides feeds upon crustaceans and small bivalves. The blackish oystercatcher H. ater preys upon the limpet Nacella magellanica which hosts two larval trematodes corresponding to the adults found parasitizing it.


INTRODUCTION
The shoreline of the Argentine Patagonian coast is an important feeding and breeding area for several coastal birds (Favero & Silva Rodríguez 2005) where 17 species, including penguins, shags, gulls, terns, ducks, oystercatchers, skuas, and petrels, breed (Yorio et al. 2005) and prey over the abundant diversity of invertebrates and vertebrate inhabiting the marine littoral and sublittoral zones (Diaz et al. 2011).In the marine ecosystems, the helminths assemblage of coastal birds (definitive hosts) reflects the presence of fish and invertebrates that are involved in their life cycle, which act as intermediate hosts and are mostly transmitted through trophic interactions, making parasites natural markers of changes in biodiversity (Marcogliese 2005).
In contrast with birds in general, studies concerning parasitic lice on aquatic birds in South America are scarce.In Argentina, Daciuk et al. (1981) presented some records of ectoparasites in birds from Península Valdés, providing the first record for lice in the Kelp Gull Larus dominicanus Lichtenstein (Laridae).Recently, Leonardi & Quintana (2017) and Leonardi et al. (2018) reported parasitological data for lice from the Imperial Shag Leucocarbo atriceps (King) (Phalacrocoracidae).However, there is no information available for the majority of marine and shorebird lice.
Knowledge on richness and diversity of bird parasites in littoral areas may provide important information about interactions, trophic webs, and compound community structure, mainly in those regions where the coastal birds abundance (mostly gulls) is increasing as a result of human activities such as fishing (Galaktionov & Skirnisson 2000, Diaz et al. 2011).Therefore, baseline information on the parasitofauna is very important to understand possible modifications in a changing world.The aim of the present work is to report both ecto and endoparasites for some of the most abundant coastal bird species from the Patagonian coast.Birds were captured with an airsoft gun under permits provided by the Wildlife Secretary of the Santa Cruz province (Resolution Number 861/08); then they were euthanized with carbon dioxide and inspected for ectoparasites by observing all the surface of the body underneath the feathers.Lice were collected using forceps and fixed in 96% ethanol.Finally, they were dissected and searched for endoparasites under a stereomicroscope.The gastrointestinal tract was separated into esophagus, stomach, and intestine; this last organ was divided into three equal sections.The body cavity, liver, pancreas, biliary vesicle, gall bladder, gonads, lungs, heart, bursa of Fabricius, cloaca, and kidneys were also examined for parasites.Helminths recovered from each section were counted, fixed in 5% hot formalin, and preserved in 70% ethanol.Cestodes were stained in Harris hematoxylin, and digeneans with Semichon's carmine or Gomori´s trichrome, dehydrated in a graded ethanol series, cleared in methyl salicylate, and mounted in Canada balsam.Nematodes and acanthocephalans were cleared in lactophenol or in 25% glycerine-ethanol.All species were studied using a light microscope and identified at the most precise taxonomic level possible (Odhner 1910, Price 1929, Wright 1956, Clay 1962, 1981, Johri 1963, Szidat 1964, Graefe 1968, Odening 1982, Bona 1994, Czsplinski & Vaucher 1994, Hoberg 1994, Khalil 1994, Navone et al. 1998, Diaz et al. 2004, Nikolov et al. 2005, Diaz & Cremonte 2010, Diaz et al. 2011, Fernandes et al. 2015, Diaz et al. 2020, Gilardoni et al. 2020).The number of parasitized hosts and the intensity of infection (number of parasites divided by number of parasitized hosts) were determined.Specimens were deposited at the Parasitological Collection of the Instituto de Biología de Organismos Marinos (CNP-Par), Puerto Madryn, Argentina.
A taxonomic summary is exposed in Table I hereas remarks of each one are presented below.

ECTOPARASITES Phthiraptera
Ischnocera Kellog, 1896Philopteridae Eichler, 1959Quadraceps Clay & Meinertzhagen, 1939 Quadraceps ridgwayi Kellogg, 1906 (Figure 1) The morphological diagnosis agrees with the species recorded by Clay (1981).The genus Quadraceps is composed of more than 100 species parasitizing mainly Charadriiformes (Palma 1995); among them Q. ridgwayi was described from the American Oystercatcher Haematopus palliatus galapagensis Ridgway from Galapagos Island.In her study about lice from Oystercatcher, Clay (1981) reported H. ater for the first time as host of Q. ridgwayi, from samples deposited in the Natural History Museum.However, the author of this record was not mentioned in the study.In the NHM Collection, there are two slides from H. ater collected by A.J. Baker in "Punta Clara, Chubut".However, this does not correspond to a real geographic location, therefore it is not clear where these samples were really collected.
Amblycera Kellogg, 1896Menoponidae Nitzsch, 1818Actornithophilus Ferris, 1916 Actornithophilus grandiceps Piaget, 1880 (Figure 2) The morphological diagnosis agrees with the species recorded by Clay (1962).The genus Actornithophilus was erected by Ferris (1916), and currently, it includes 36 species parasitizing Charadriiformes (Clay 1962).In her key to the species of Actornithophilus, Clay (1962) analyzed samples from H. ater from different locations along the South American coast, but there is Table I.Ecto and endo parasites species recorded in the studied coastal birds from Puerto Deseado, Patagonian coast, Argentina.Mean intensity of infection is given followed by the range in parenthesis.The morphological diagnosis agrees with species of the genus Tethrabothrius (Hoberg 1994).This genus is widely distributed among marine mammals and birds, including more than 40 species parasitizing seabirds (Hoberg 1994, Schmidt 1986).There are two previous records for the genus from birds on the Patagonian coast.One of these is Tetrabothrius cylindraceus (Rudolphi) reported in L. dominicanus, the other one is Tetrabothrius lutzi Parona, parasitizing the Magellanic Penguin, Spheniscus magellanicus Foster (Spheniscidae) (Diaz et al. 2010(Diaz et al. , 2011)).In this study, specimens of Tetrabothrius were found in L. dominicanus, and because of the lack of mature proglottids, we could not determine them at species level.Progynotaenia sp.(Figure 3)

Coastal bird host
The morphological diagnosis agrees with species of the genus Progynotaenia (Johri 1963, Khalil 1994, Nikolov et al. 2005).The family Progynotaeniidae mostly parasites charadriiform birds and has been reported in different regions of the world (Johri 1963).In America, a single undescribed species of the genus Proterogynotaenia was reported in the American Oystercatcher Haematopus palliatus Temminck in Chile (Mariaux et al. 2017).There are disagreements about the location of many species into this genus or into Paraprogynotaenia (Nikolov et al. 2005).Following Khalil (1994), specimens collected in the present study in  Gymnophallus australis Szidat, 1962 The morphological diagnosis agrees with the species recorded in L. dominicanus from northern Patagonia, Argentina (Diaz et al. 2011).The species was originally described as Gymnophallus australis (metacercariae parasitizing the mussel Mytilus edulis Linnaeus (Mytilidae) and then reassigned by the same author to the genus Parvatrema (Szidat 1965).Cremonte et al. (2008) re-described the species from cultured metacercariae and adults obtained in the laboratory from intertidal mussels and reassigned again to the genus Gymnophallus.
Gymnophalloides nacellae Cremonte, Pina, Gilardoni, Rodrigues, Chai & Ituarte, 2013 The study of the specimens collected in this study allowed the description of the adult form of Gymnophalloides nacellae (Gilardoni et al. 2020).The metacercaria was described by Cremonte et al. (2013)  The morphological diagnosis agrees with species of the genus Levinseniella (Szidat 1964).Several bird species were recorded as host of this trematode in different areas of Argentina (Szidat 1964, Lunaschi & Drago 2007).In Patagonia, L. cruzi was reported in L. dominicanus and L. maculipennis from lakes of the Río Negro and Neuquén provinces (Szidat 1964).In marine areas, this species was recorded in C. bairdii from the Chubut province (Capasso et al. 2019).The present finding represents the southernmost record of this genus.It is necessary to study the specimens to know whether they belong to an already described species or an undescribed one.
The morphological diagnosis agrees with the species recorded parasitizing L. dominicanus from the northern Patagonian coast, Argentina (Diaz et al. 2011).By the study of the new specimens recovered from the same host species and from C. fuscicollis, based on some morphological differences but clearly distinguished by molecular features, J.I.  (Bagnato et al. 2015, Gilardoni et al. 2019).It means that two renicolid species cohabit on the Patagonian coast; the adult found in L. dominicanus could be a different species than that parasitizing L. specularioides.A renicolid metacercaria belonging to the same species to the redia found in T. geversianus was recorded in the mussel M. edulis (Bagnato et al. 2015).
Other renicolid metacercariae were found parasitizing the limpet N. magellanica and the bivalves Lasaea adansoni and G. trapesina on the Patagonian coast (F.Cremonte & C. Gilardoni unpublished data).Species (as an adult stage) of this genus are recorded for the first time in Argentina.

Schistosomatidae Stiles & Hassall, 1898
Schistosomatidae gen.et sp.indet.(Figure 10) The morphological diagnosis agrees with species of the family Schistosomatidae (Odhner 1910, Price 1929).Two species were recorded in birds from Argentina; Dendrithobilharzia rionegrensis Martorelli, 1981  The morphological diagnosis agrees with the species recorded parasitizing L. dominicanus from the northern Patagonian coast, Argentina (Diaz et al. 2011).This acuariid nematode has a wide geographical and host distribution (Diaz et al. 2011).In Larus spp., this species has been found in Canada, Brazil, Spain, New Zealand, and Chile (Diaz et al. 2011).In Argentina, the species was reported parasitizing the Magellanic Penguin and the Kelp Gull (Diaz et al. 2001(Diaz et al. , 2010(Diaz et al. , 2011)).The species showed great morphological stability and it was concluded that it has high adaptability to different hosts and localities (Diaz et al. 2011).

Paracuaria adunca (Creplin, 1846)
The morphological diagnosis agrees with the species recorded parasitizing L. dominicanus from the northern Patagonian coast, Argentina (Diaz et al. 2004).This is a frequent nematode parasitizing several piscivorous birds (e.g.Laridae, Gaviidae, Podicipedidae, Diomedeidae, Anatidae) and widely distributed in North and Central America, Europe, and Asia (Anderson & Wong 1982).It was reported for the first time in South America and for L. dominicanus and later, the species was found from the same host in Chile (see Diaz et al. 2004Diaz et al. , 2011)).(Garbin et al. 2019a).Among them, species of Contracaecum Raillet and Henry, 1912 were registered in different Patagonian birds (Garbin et al. 2019b).

DISCUSSION
A total of 2 ectoparasites and 19 endoparasites taxa were recovered from the 4 coastal birds species here studied: 6 from Haematopus ater, 11 from Larus dominicanus, 3 from Leucophaeus scoresbii, and 5 from Lophonetta specularioides.
The study of ectoparasites, particularly lice, in aquatic birds from Argentina is very scarce.Most of the host-parasite associations known were described by materials collected in the country and later deposited abroad in museum collections such as the Natural History Museum of London, or the Kellogg Collection, University of California, USA.In this work, we only found two lice species, Quadraceps ridgwayi and Actornithophilus grandiceps from H. ater.Both of them were previously recorded parasitizing H. ater but without precise bibliographic references.Only one previous work focused on the lice of shorebirds in Argentina.Daciuk et al. (1981) reported three species parasitizing the Kelp Gulls from Península Valdés, Austromenopon transversum.Quadraceps punctatus, and Saemundssonia (Saemundssonia) lari.In a recent study, we analyzed and compared the community structure of lice infesting Kelp Gulls from anthropogenic environments, i.e. a urban waste landfill and fisheries discards, from two different locations in Argentina (E.Lorenti et al., unpublished data).In Puerto Madryn, Patagonia, we found 2 of the lice species previously reported as parasites of Kelp Gulls, S lari, and A. transversum.Eighty percent of the gulls were infested by at least one of these species.Despite there are no meaningful differences between populations, no latitudinal differences have been studied along the distribution of Kelp Gulls.In this sense, we assumed that the absence of lice might reflect a lower prevalence in this geographical area.In their recent work with shorebirds in Perú, Tavera et al. ( 2019) reported a prevalence of 62% Philopteridae and 49% Menoponidae.Despite the low number of birds analyzed in our work, the low infestation rates in Perú agree with our results.However, further research is needed to compare the ecology of lice in shorebirds and the possible differences between locations and host species.
This survey reports several new records of helminthes.Five species, Renicola sp. 1 from Larus dominicanus, Levinseniella sp., and Renicola sp. 2 from Lophoneta specularioides, and Paramonostomum sp. and Progynotaenia sp. from H. ater, are recorded for the first time in the mentioned coastal birds.For all birds, the helminth community was dominated by digeneans.These coastal birds feeding upon the intertidal zones and these areas are dominated by digeneans due to the high diversity of invertebrates acting as intermediate hosts.
Almost all the helminth species recovered parasitizing L. dominicanus in this survey were already previously recorded in Argentina (Diaz et al. 2011, Brant et al. 2017) excepting Renicola sp. 1.For the rest of the coastal birds analyzed, all findings represent new records, mainly because until now, parasite surveys for these bird species were practically non-existent.The three taxa (1 cestode and 2 digeneans) recorded for L. scoresbii and the four taxa (1 cestode and 3 digeneans) recorded for H. ater are the first records for these birds worldwide.Only 2 nematode species were previously recorded for L. specularioides (Agüero et al. 2015), then the five taxa (1 cestode and 4 digeneans) recovered in this survey constituted new records parasitizing this duck species.
This study contributes to the knowledge on marine biodiversity and elucidation of the parasites life cycles.Marine endoparasites are mainly transmitted using food webs; invertebrates usually act as intermediate hosts and vertebrates as definitive hosts (Lafferty et al. 2008).Therefore, birds parasites, the main top predators on the intertidal areas, can be indicators of diet and feeding habits.
Parasites of the Crested Duck L .specularioides allow us to infer that these birds feed upon crustaceans, which transmit two microphallid digeneans, and unknown bivalves which transmit the renicolid digenean.Notocotylid digeneans life cycles involve aquatic gastropods as intermediate hosts; cercariae usually encyst on vegetation or sometimes on the outer shell and/or operculum of the snail first intermediate host (Yamaguti 1975).

*
Total number of cestodes from one kelp gull cannot be determined because the scolices were not found.

Table I .
Continuation.
Progynotaenia, being the first record of the family Progynotaeniidae in Argentina.