Browsing by Author "Soares, Marta S. C."
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- Agonistic and predatory behaviour of the lizardfish Synodus saurus (Linnaeus, 1758) (Actinopterygii: Synodontidae) from the AzoresPublication . Soares, Marta S. C.; Barreiros, João P.; Sousa, Luis; Santos, Ricardo S.The behaviour of the lizardfish Synodus saurus, a common demersal predator in Azorean waters, is described. A total of 25 hours’ qualitative diurnal underwater observations were carried out between July 2000 and January 2001. Behavioural aspects are presented, illustrated with diagrams based on in situ observations. S. saurus is a cryptic predator that feeds mainly of small pelagic, gregarious fish; it is primarily associated with soft bottom substrate. Besides remaining camouflaged buried beneath the sand, S. saurus is a highly mobile predator capable of rapidly swimming more than five meters to capture its prey. S. saurus maintains a territory through agonistic interactions, and also interacts non-agonistically with heterospecifics such as Bothus podas maderensis.
- Feeding habits of the lizardfish Synodus saurus (Linnaeus, 1758) (Actinopterygii: Synodontidae), from the AzoresPublication . Barreiros, João P.; Sousa, Luis; Soares, Marta S. C.The feeding habits of the lizardfish Synodus saurus were study in the Azores archipelago, north-eastern Atlantic. Factors examined were diet composition, prey importance, season, fish size, feeding strategy and prey orientation in the oesophagus. The stomach contents of 308 specimens were collected and analyzed between March and November 2000. Synodus saurus is common in Azorean water. Though it prefers small gregarious pelagic fish, it also feeds on epibenthic and benthic prey. We found the following prey in its diet: 9 families of teleostean fishes (Carangidae, clupeidae, Cynoglossidae, Gobiidae, Labridae, Myctophidae, Spaidae, Spyraenidae and Synodontidae), two families of crustaceans (Cymothoidae and Scyllaridae) and one of cephalopods (Loliginidae). The European pilchard, Sardina pilchardus was the commonest prey. The diet of the lizardfish varies with the season, showing the greatest diversity (given by the Shannon-Wiener index) in October. There is a significant correlation with the sea temperature. The size of the predator is not correlated to the size of its prey. However, we observed a positive correlation between the size o the positive correlation between the size of the predator and the quantity of food in its stomach. The orientation of the prey in the oesophagus may partly depend on the predator’s size. However, analysis of the stomach contents provided no information on the selection of prey.
- Following associations with the striped red mullet Mullus surmuletus Linnaeus, 1758 (Perciformes: Mullidae) from the AzoresPublication . Soares, Marta S. C.; Barreiros, João P.In this study we report Mullus surmuletus being followed intraspecifically and by individual fish of the following species: Thalassoma pavo, Coris julis, Diplodus sargus cadenati and Serranus atricauda. This study was carried out over a total of some thirty-five hours between October 2001 and August 2002, in shallow water over sandy bottoms in the vicinity of the islands of Terceira and São Miguel, Azores (NE Atlantic). Red mullet search for benthic animals in the sand with their snout and barbells and feed on them. This behaviour attracts the attention of other species, which take advantage of the disturbance and capture prey themselves. Cleaning behaviour was also observed between M. surmuletus – "clients" and T. pavo and C. julis – "cleaners". This cleaning behaviour occurs when the "cleaners" follow the red mullet.
- Juvenile Sphyraena viridensis, preyed by the lizard fish Synodus saurus. A new predatory association from the AzoresPublication . Barreiros, João P.; Cardigos, Frederico; Soares, Marta S. C.; Machado, Leonardo F.Les juvéniles de Sphyraena viridensis, proies de Synodus saurus, une nouvelle association prédateur-proie aux Açores. Au cours d’un travail sur l’écologie (comportement, alimentation et reproduction) du poisson lézard, Synodus saurus, aux Açores (Atlantique NE) nous avons découvert, dans plusieurs contenus stomacaux, des exemplaires postlarvaires et des juvéniles de la bécune à bouche jaune Sphyraena viridensis. Non seulement cette découverte nous a permis d’obtenir, pour la première fois, des postlarves de cette espèce de barracuda mais nous avons réussi à décrire une action de prédation d’un poisson épibenthique envers une espèce pélagique.
- The parasitic isopod Anilocra physodes, as a novel food source for the lizardfish Synodus saurus (Synodontidae).Publication . Narvaez, Pauline; Barreiros, João P.; Soares, Marta S. C.During a wide project carried out on the behavior and reproduction of the Atlantic lizardfish Synodus saurus in the Azores (NE Atlantic), specimens of the ectoparasitic isopod Anilocra physodes were discovered in various stomachs contents of these piscivorous predatory fish. This intriguing result allowed us to conclude for the first time that fish species can ingest their own parasites, which becomes doubly beneficial, since it releases them from para- sites but it is also a new food source.
- Preliminary notes on the reproductive biology of the lizardfish, Synodus saurus (Actynopterygii: Synodontidae) in the AzoresPublication . Sousa, Luis; Barreiros, João P.; Soares, Marta S. C.; Hostim-Silva, Maurício; Santos, Ricardo S.Between March and November 2000, 307 specimens of the lizardfish Synodus saurus (Linnaeus 1758) were captured on several coastal areas of Terceira Island, Azores. This species is an important coastal epibenthic predator. Although common, its biology, namely its reproduction, is virtually unknown. During the study period, 206 females (155 mm to 460 mm TL) and 101 males (269 mm to 290 mm TL), were captured. Sex ratio was 2:1 with more males in June. Gonados-somatic Index (GSI) for females and males attained its maximum values during Spring and Summer, showing that these are the most intensive reproduction periods. Hepato-somatic Index (HSI) suggests that this species may well recur on body reserves for energy metabolization in gonad development. Nevertheless, more studies are necessary in order to confirm this assumption. Ovarian histology, presenting different oocytarian phases, indicates that this species has an asynchronous posture. The male increment of June, associated to higher GSI values, suggests that this could represent a moment of intense competition for females, within the studied area.
- Temperate facultative cleaner wrasses selectively remove ectoparasites from their client-fish in the AzoresPublication . Narvaez, Pauline; Furtado, Miguel; Neto, Ana I.; Moniz, Isadora; Azevedo, José M. N.; Soares, Marta S. C.Cleaner fishes are key contributors to the health of fish communities. However, much of the information in the literature refers to tropical systems, while fewer studies have examined the activity of cleaner fish inhabiting temperate ecosystems. Facultative cleaner fish are assumed to clean only during their juvenile phase, and have a broader diet than obligatory cleaner fish. Here, we focused on 2 facultative cleaner fish species, Coris julis and Thalassoma pavo, that live along the temperate coasts of the Azorean island of São Miguel. We found that these species focused their cleaning activities on relatively few species of clients, which supports the general idea that facultative cleaner fishes in temperate waters are less dependent on cleaning interactions than obligatory cleaner fishes in tropical waters. Both cleaner species were found to give more bites per host when inspecting larger clients, likely because the latter typically host more parasites. We found that C. julis consumed a greater diversity of food items, which included gnathiid larvae and fewer caligid copepods, compared to T. pavo where no ectoparasites were found. All cleaner fish that we collected after observations of cleaning had eaten gnathiid isopod larvae but not caligid copepods, even though caligid copepods were the most abundant ectoparasite found on the body of 7 selected fish species (including both client and non-client species), suggesting that both species selectively feed on gnathiid isopods. This study is the first to demonstrate that temperate facultative cleaner fish species actively and selectively inspect and remove ectoparasites from their client-fish species.