Gobiesox Marmoratus Research Articles

Modelling seasonal patterns of larval fish parasitism in two northern nearshore areas in the Humboldt Current System

Macro- and micro-environmental factors modulate parasite loads in fish, determining parasitic abundances, diversity, and interaction dynamics. In this study, seasonal variations in larval ectoparasites on fish larvae in the northern Humboldt Current System (HCS) were evaluated using a delta-gamma generalized linear model to predict their occurrence frequencies. Fish larvae were collected from two nearshore areas during austral spring–summer and autumn–winter. Only five (of 38) larval fish species were parasitized by copepods: Gobiesox marmoratus, Ophiogobius jenynsi, Helcogrammoides cunninghami, Myxodes sp., and Auchenionchus crinitus. A binomial model showed that the presence/absence of parasitized fish larvae varied among the fish species and their larval abundances, while a positive delta-gamma model showed that ectoparasite frequency varied among the seasons and fish species. Seasonal variations in parasitized fish larvae frequency could be associated with host and parasite reproductive processes, which are related to oceanographic features responsible for larval retention and subsequent higher infestation probabilities. Host length was positively correlated with ectoparasite length, suggesting early infection and combined growth until the detachment of the ectoparasite. Our results suggest that infestation patterns in larval fish species can be identified using delta-gamma models and that they respond to local (retention) and high-scale (HCS) processes.

Larval parasitic copepods affect early life history traits of a temperate clingfish.

Larval copepods are frequent parasites that infest fish larvae along the Chilean coast. Because these parasites develop on fish during the early development, when their bodies are fragile and in a recent stage, they can affect the fishes' early life history traits (ELHT). The goal of this study was to determine the effect of parasitic copepods on the ELHT of the larvae of the clingfish Gobiesox marmoratus (Teleostei: Gobiesocidae) using otolith microstructure analysis. Ichthyoplankton samples were collected during austral winter (July and August 2012), in the inner shelf waters off Valparaiso Bay, central Chile. A total of 95 non-parasitized larvae (NPL) and 95 parasitized (PL) with copepods were randomly selected for subsequent analyses. Parasitized larvae of G. marmoratus were larger than NPL. The right otolith tended to be larger than the left otolith in the fish larvae, but with a higher asymmetry in PL. The PL showed larger otoliths-at-size than the NPL, particularly in smaller larvae (< 8mm of standard length, SL). Nonetheless, parasitized larvae larger than 8mm SL showed the opposite trend that is smaller-at-size otoliths than NPL. The Gompertz models indicated that the asymptotic length of NPL doubled the length of PL; this suggests that parasitic copepods affect the maximum size attained by the PL. In conclusion, parasitic copepods negatively affect the ELHT of G. marmoratus larvae and the greater asymmetry can be attributed to parasitism.

Lunar influences in the diet habits and selectivity of larval clingfish Gobiesox marmoratus.

The influence of the lunar cycle on the feeding habits, feeding success and selectivity was tested in situ on larval stages of the clingfish Gobiesox marmoratus (Gobiesocidae). Gobiesox marmoratus larvae and their prey were collected in the water column during the lunar cycle in austral spring 2015 and 2016, in shallow waters (<30 m depth) of El Quisco, central Chile. Feeding incidence was high (80-100%) throughout the moon cycle. The diet was composed of 32 prey items, being gastropod larvae and invertebrate eggs the most important. Prey composition varied among lunar phases with the lowest prey richness during new moon. During 2016, G. marmoratus larvae ingested the lowest number, but the largest prey during new moon. In spring 2015, there were no significant changes in the abundance of each prey taxon in the water column among moon phases, but in spring 2016 there were significant differences in the abundance of cypris and copepod nauplii, particularly between full and new moon. Feeding selectivity index showed that gastropod larvae were positively selected throughout the lunar cycle during spring 2015. In spring 2016, invertebrate eggs were selectively ingested in full moon and third quarter, but at a new moon G. marmoratus larvae selected gastropod larvae. Mean temperature of the water column and its vertical gradient and nocturnal cloud cover influences the feeding success of larval G. marmoratus. Lunar illumination favoured only an increase of richness of prey items. Therefore, nocturnal cloud cover precludes a greater influence of lunar illumination in the larval trophic ecology of this crypto-benthic fish.

Parasitic copepods affect morphospace and diet of larvae of a temperate reef fish.

The effects of ectoparasites on larvae of the clingfish Gobiesox marmoratus were evaluated at the dietary and morphometric levels. The larvae and ectoparasites were collected by nearshore plankton samplings during October, November and December 2013 off El Quisco Bay, central Chile. The standardized abundance of total larvae and those ectoparasitized larvae (PL) was positively related and high parasite prevalence was found throughout the sampling period (up to 38%). Geometric morphometrics analyses indicate main changes in the shape through early ontogeny and subtle but significant variations between PL and non-parasitized larvae (NPL). Prey composition varied between PL and NPL; small size (<6 mm standard length, LS ) parasitized larval G. marmoratus ate mostly gastropod larvae, whereas small non-parasitized specimens ate mainly cirripede nauplii. All larger (>8 mm LS ), pre-settlement stages parasitized by Trifur and, or Caligus copepods had content in their gut, suggesting that ectoparasites did not diminish prey capture in host with larger size. Morphometric and dietary changes occurring during larval development were decoupled, both for PL and NPL. The maintenance of a slender, more hydrodynamic body through pelagic development and the ingestion of less-mobile prey in PL suggests non-lethal effects of ectoparasitism on rocky-reef fish larvae.

Sharing morphospaces: early ontogenetic shape changes in two clingfish larvae (Pisces: Gobiesocidae) from the south-east Pacific Ocean.

Larval body shape changes and developmental timing were examined in two clingfish species from the south-east Pacific Ocean, Gobiesox marmoratus and Sicyases sanguineus. Ontogenetic allometry showed no interspecific variation and <7 mm standard length (LS ) larvae of both species occupied similar morphospace, but larger G. marmoratus showed increased body depth while larvae of S. sanguineus developed a flattened head and maintained a hydrodynamic body. Estimated developmental timing suggests that larval body shape changes were faster in G. marmoratus than in S. sanguineus prior to settlement.

Variaciones espacio temporales de la estructura comunitaria de endoparasitos en peces intermareales de Chile central: descriptores parasitologicos, composicion de especies y anidamiento

The parasite community structure in fish species of Chile have scarcely been analysed through time and locations, making it difficult to understand the spatio-temporal variation patterns. In this study, we investigated whether the endoparasitic community of three intertidal fishes in central Chile exhibited spatial or temporal changes. We collected a total of 954 individuals of Helcogrammoides chilensis , Gobiesox marmoratus and Scartichthys viridis in the intertidal rocky zone in localities close to the bays of Valparaiso (~32o45’S, 33o30’S) and of Concepcion (~36o28’S, 36o41’S), during in 2013 and 2014. We analized the endoparasite community for each host according to their numerical descriptors, species composition and nestedness, comparing these communities as a function of both space and time. The average richness, abundance and diversity of the parasite infracommunity did not exhibit significant difference between localities (Valparaiso vs Concepcion) for any of the host species. Only the parasitological descriptors of H. chilensis and G. marmoratus showed significant difference between years for Valparaiso. Similarity of parasite composition of each host species was low between years and geographical localities. The endoparasite infracommunity of S. viridis exhibited a nestedness pattern over time and space, unlike G. marmoratus that showed a random pattern over time and space. We concluded that spatio-temporal scales seem to be important factors for endoparasite community organization, but they affect different host species differently. The repeatability seems to be associated with the host species biology and the aggregate characteristics of the parasitic communities. However, our results suggest that other factors, such as environmental and/or ecological features, could impact on the community structure of parasites.

A new species of Hemipera Nicoll, 1913 (Digenea: Derogenidae) from fishes of the intertidal rocky zone of Chile.

A new species, Hemipera cribbi sp. nov., is described. This trematode was found in three intertidal fish species: Scartichthys viridis (Valenciennes) (Blenniidae), Gobiesox marmoratus Jenyns (Gobiesocidae) and Myxodes viridis Valenciennes (Clinidae) from the central and southern coast of Chile. Of 233 individuals of S. viridis from the central coast examined, 19 were infected. From the southern coast, nine individuals of S. viridis (one infected), five individuals of G. marmoratus (four infected), and 16 individuals of M. viridis (one fish infected) were examined. Hemipera cribbi sp. nov. is distinguished from the five other congeneric species mainly in the body size, being the smallest and narrowest species in the genus, reaching five times longer than wide. This is the first species of the genus described for the South Pacific Ocean off South America. ITS2 rDNA sequences of Hemipera cribbi sp. nov. from each host and locality were identified.

Nestedness of parasite communities of intertidal fish in central Chile: how influential is the body length of the host?

&lt;p class="Default"&gt;La estructura de la comunidad de parásitos, determinada mediante análisis de anidamiento, varía considerablemente en función de la especie hospedera y el tamaño corporal de la misma. El patrón anidado es aquel en el que comunidades pobres en especies constituyen subunidades de comunidades de mayor riqueza, lo cual también se observa en las comunidades de parásitos. Existen grandes diferencias de riqueza y abundancia de parásitos en función del tamaño del hospedero. Por lo tanto, en este estudio determinamos, mediante análisis de anidamiento, si la estructura de la comunidad de parásitos de peces del intermareal, se relaciona con la longitud corporal de los hospederos y los descriptores parasitológicos. Se recolectaron 2 435 individuos de cinco especies de peces del intermareal rocoso de Chile central (32º02’-33º57’ S y 70º30’- 70º30’ W); &lt;em&gt;Helcogrammoides chilensis,&lt;/em&gt;&lt;em&gt; Scartichthys viridis, Auchenionchus microcirrhis, Gobiesox marmoratus &lt;/em&gt;y&lt;em&gt; Sicyases sanguineus&lt;/em&gt;. Cada especimen fue revisado con respecto a sus parásitos y medido en su longitud total (LT). Las cinco especies muestreadas fueron clasificadas en función de la longitud corporal (LT) en tres rangos, cada uno de los cuales constituye una infracomunidad del estudio, y para la que se calculó el índice de anidamiento. Se emplearon los modelos NTCP (Nestedness Temperature Calculator Program) y NODF (Nestedness metric based on the Overlap and Decreasing Fill), utilizando la presencia/ausencia de especies parásitas. También se empleó el modelo WNODF (Weighted – NODF) utilizando la abundancia de parásitos por especie. Así mismo, se calculó la riqueza total de especies, el promedio de riqueza, abundancia, diversidad y dominancia a nivel de la infracomunidad, para relacionarlos con los índices de anidamiento. Las infracomunidades de parásitos de la mayoría de las especies presentaron patrones de anidamiento, excepto en &lt;em&gt;G. marmoratus&lt;/em&gt; y &lt;em&gt;H. chilensis,&lt;/em&gt; en algunos de sus rangos de LT. No se encontró una relación directa entre el índice de anidamiento y la LT de los peces. Sin embargo, se observaron correlaciones directas de los índices de anidamiento con la riqueza promedio, abundancia y la diversidad infracomunitaria de parásitos, pero no con la riqueza total, que mostró una correlación inversa con la LT del hospedero. Además, se detectó anidamiento en la comunidad componente de parásitos en todas las especies de peces. Concluimos que las comunidades de parásitos de peces provenientes de la zona intermareal son estructuradas y predecibles, y se encuentran vagamente condicionadas por la LT de los hospederos y las características agregadas de los parásitos, especialmente a un nivel infracommunitario.&lt;/p&gt;

Is ectoparasite burden related to host density? Evidence from nearshore fish larvae off the coast of central Chile

Variations in parasite populations may be temporal and/or spatial and can occur in relation to environmental factors. However, such changes may also occur due to differences in host population density, which is one of the main factors that affect the abundance of directly transmitted parasites. Fish larvae and their ectoparasites were collected via ichthyoplankton samplings during a 3-year survey near the coast of central Chile. To estimate the variations in ectoparasite abundance that occurred with fluctuations in host density, the prevalence and intensity of ectoparasites (copepods and isopods) were calculated and compared with the density (i.e., the larval fish abundance standardized to 1,000 m−3) of six species of nearshore fish larvae that belonged to the families Gobiesocidae, Labrisomidae and Tripterygiidae. Copepods (Penellidae and Caligidae) and isopods (Cryptoniscidae) were found to be parasitizing the fish larvae. Pennellid copepods were the most prevalent ectoparasite, and the clingfish Gobiesox marmoratus (Gobiesocidae) was the most parasitized fish species (12.81 %). The individual burdens of pennellid, caligid and isopod ectoparasites failed to exhibit any correlation with the larval densities of four fish species (i.e., Auchenionchus crinitus, Auchenionchus microcirrhis, Sicyases sanguineus and Helcogrammoides chilensis). Nonetheless, the prevalence and intensity of the pennellid copepods exhibited a significant and positive correlation with the density of a gobisesocid species. In contrast, the prevalence of pennellid copepods (5.10 %) exhibited a significant but negative correlation with the density of tripterygid fish. Ectoparasite abundance is a result of a species-specific relationship with their hosts, but the evidence found suggests no correlation between ectoparasite burden and host density in larval fishes from coastal environments.

The life cycle of Prosorhynchoides carvajali (Trematoda: Bucephalidae) involving species of bivalve and fish hosts in the intertidal zone of central Chile.

We describe the life cycle of the bucephalid Prosorhynchoides carvajali from the intertidal rocky zone of central Chile. To elucidate the life cycle of this digenean, two mytilid bivalves, Semimytilus algosus and Perumytilus purpuratus, and ten intertidal fish species belonging to the families Blenniidae, Tripterygiidae, Labrisomidae, Kyphosidae and Gobiesocidae were analysed for natural infections. In addition, experimental infections of fish were undertaken and molecular analyses were performed of several developmental stages of the digeneans in various host species. Experimental infections of fish were made from infected mytilids to determine which fish species were suitable for the metacercarial stage of Prosorhynchoides. We also determined the abundance and prevalence of metacercariae in natural infections in fish and found that they were lower than in the experimental infections. A molecular analysis showed that sporocysts from S. algosus were identical to metacercariae from five fish species and P. carvajali adults. Sporocysts isolated from P. purpuratus were similar to metacercaria found in one fish species only (G. laevifrons) but were different from P. carvajali, with 1.9-2.0% genetic divergence. Therefore, the complete life cycle of P. carvajali consists of the mytilid species S. algosus as the first intermediate host, at least five intertidal fish species as second intermediate hosts (Scartichthys viridis, Auchenionchus microcirrhis, Hypsoblennius sordidus, Helcogrammoides chilensis and Gobiesox marmoratus), two carnivorous fish as definitive hosts (Auchenionchus microcirrhis and A. variolosus) and one occasional definitive host (Syciases sanguineus). This is the second description of a life cycle of a marine digenean from Chile.

Planktonic duration in fourteen species of intertidal rocky fishes from the south-eastern Pacific Ocean

The planktonic duration (PD) was determined in fourteen intertidal rocky fishes from the south-eastern Pacific Ocean by counting the otolith micro-increments from hatch check to a transition mark (TM). TMs were validated by comparing the PDs estimated from post-settlers with the total increment counts from otoliths of more recent (new) settlers. In 11 species (79%), the most common TM corresponded to a notable decrease in increment width after settlement. The PDs ranged from 45 days in the kyphosid Girella laevifrons to 135 days in the labrisomid Auchenionchus variolosus, and eight species (57%) had mean PDs of longer than three months. The mean observed size-at-settlement (SASM) values ranged from 17.5 ± 7.2 mm TL in Gobiesox marmoratus (Gobiesocidae) to 40 ± 5.5 mm TL in Calliclinus geniguttatus (Labrisomidae) and showed low variability within species of the same family. PDs were markedly longer in intertidal rocky fishes than in other littoral and reef fishes in tropical and temperate waters. A lengthy and variable duration of the pre-settlement phase, along with a relatively consistent size-at-competence within closely related species, are suggested as mechanisms through which these fishes may increase their probability to settle in the spatially restricted habitat of exposed rocky pools.

Parasites communities in the clingfish Gobiesox marmoratus from central Chile

This study investigated the factors (i.e., season, locality, sampling year, total length and maturity stage of the hosts) that might influence the structure of parasite populations and communities in the clingfish Gobiesox marmoratus. The parasite community was described and analyzed using numerical descriptors, such as prevalence, intensity and species richness, between factors previously mentioned. A total of 260 clingfish were collected from 2 localities of central Chile, four seasons and during 3 year cycles (from July 2006 to July 2009). In the whole clingfish sample, 668 parasites were found, which belonged to 14 parasite taxa; 9 of them were new records in G. marmoratus. Parasite infracommunity richness ranged 0-3 species, although 1 trematode species, Helicometrina nimia, represented 80% of all parasites collected and was the most abundant and prevalent parasite species. The average of parasite abundance and intensity (± SD) was 2.5 ± 8.2 and 7.5 ± 12.7, respectively. Generalized linear model showed that parasite communities were influenced by season, locality, sampling year, and maturity stage when considering the abundance and intensity of parasites. For the parasite richness, only the locality and maturity of fish was determinant for explaining the differences. The populations and communities of the parasite variations were variable due to differences in fish body length because prevalence, abundance and intensity of parasites significantly correlated with the fish body length. Concordantly, maturity fish were longer than immature fish. Thus, clingfish from El Tabo were longest and mature, which harbored higher parasite richness than those fish from Las Cruces.

The contrasting hatching patterns and larval growth of two sympatric clingfishes inferred by otolith microstructure analysis

Larval abundance, age, growth and hatching patterns of two sympatric clingfishes, Gobiesox marmoratus and Sicyases sanguineus (Pisces, Gobiesocidae), were estimated by using otolith microstructure analysis and compared on the basis of collections performed during the austral spring in 2010 off the coast of central Chile. G. marmoratus larvae were more abundant than S. sanguineus larvae during the study period. For both species, the sagittae deposited micro-increments during embryonic development (before hatching) and a hatch mark was observable in all examined otoliths. The sagittae otoliths of G. marmoratus grew in radius, perimeter and area faster than did the otoliths of S. sanguineus. Both species showed significant (P &lt; 0.05) differences in larval growth and lunar periodicity of the hatching events. G. marmoratus hatched at smaller sizes (2.6 mm) mainly during the first-quarter moon and the larvae grew at rates of 0.24 ± 0.01 mm day–1. S. sanguineus hatched as larger larvae (&gt;3 mm) during the first-quarter and full moons and grew at slower rates (0.14 ± 0.01 mm day–1) during the initial 25 days. The high abundance of larval clingfish in near-shore waters, temporal decoupling among the hatching events, and the different growth rates may be tactics to increase self-recruitment in coastal waters.

Influence of tidal phase and circulation on larval fish distribution in a partially mixed estuary, Corral Bay, Chile

The influence of circulation on abundance patterns of larval fish was compared at different phases of the tide in the vicinity of an estuarine front in Corral Bay, Chile during austral spring. Greatest differences in water salinity were found across the frontal region on ebb tides. Because rainfall was low, density differences were primarily due to tidal intrusion of salt water. Larval density was relatively low during both sampling periods with Strangomera bentincki, Oodntesthes regia laticlavia, Gobiesox marmoratus and Hypsoblennius sordidus as the most abundant species. Total ichthyoplankton was always higher near the tidal front (Stations 2 and 3). Spatial distribution in relation to tidal phase showed different patterns for the most abundant fish larval species. Circulation and larval distribution revealed that the bay was a source of young fish larvae but older individuals could also be recruited in and retained there. Results show that the front could act as a physical boundary for larvae transported from offshore through specific mechanism of circulation related with the tidal regime.

Spiracanthus bovichthys n. gen. n. sp. (Acanthocephala: Arhythmacanthidae), a parasite of littoral fishes of the central south coast of Chile.

A new acanthocephalan species, Spiracanthus bovichthys n. gen. n. sp., is described. Samples were taken from 26 marine fish species between 23 and 53 degrees S of Chile. The parasite was found in the intestine of 6 species and only between 36 and 40 degrees S, especially in those fish that prey on small crustaceans in the upper and sublittoral zone. The parasite was found in Bovichthys chilensis (Reagan). Auchenionchus variolosus (Valenciennes), Calliclinus genigutattus (Valenciennes), Sindoscopus australis (Fowler and Bean), Myxodes cristatus Valenciennes, and Gobiesox marmoratus (Jenyns). However, only the first species is a suitable host for the parasite as evidenced by the presence of mature females. This acanthocephalan belongs to Arhythmacanthidae, but it does not correspond to any genus described. Spiracanthus bovichthys is different in the number and spiralled distribution of its hooks in the proboscis. In the short proboscis, 3 groups of hooks are distinguished according to size, summing up to 150-190 hooks. The group of largest hooks are found in the apical part of the proboscis, and there are 10 diagonal rows of small hooks from the prebasal to basal proboscis. Its trunk is covered partially by small spines. Amphipod and isopods were the prey items shared among the host fish species and are the best candidates to be the intermediate hosts of S. bovichthys.