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The Diets in Four Pacific Tube Blennies (Acanthemblemaria: Chaenopsidae): Lack of Ecological Divergence in Syntopic Species
Abstract
The diets of three syntopic Gulf of California Acanthemblemaria (A. balanorum, A. crock-eri and A. macrospilus) and A. castroi from the Galapagos Island are nearly uniformly composed of harpacticoid copepods and other small benthic-vagile or planktonic crustaceans. On occasion, large prey items such as crabs or other small fishes are taken. HORN'S index of niche overlap indicates that the three syntopic Acanthemblemaria are not separated along the food resource utilization axis. Slight variations in diets among the syntopic species seem to be related to differences in degree of microhabitat specialization.
... They generally feed on small crustaceans, in particular copepods; darting out from refuge holes to collect passing prey. However, chaenopsids also attack other invertebrates and have extremely large jaws for their body size (Kotrschal and Lindquist, 1986;Clarke, 1992Clarke, , 1999, which facilitates the opportunistic ingestion of larger prey such as amphipods, shrimp, crabs, and even small fish that enter their feeding zone (Lindquist and Kotrschal, 1987). Prey can be taken from the benthos or plankton (Lindquist and Kotrschal, 1987;Clarke, 1999) and for Acanthemblemaria spp., sessile invertebrates are often removed with chisel-like incisors (Kotrschal and Lindquist, 1986). ...
... However, chaenopsids also attack other invertebrates and have extremely large jaws for their body size (Kotrschal and Lindquist, 1986;Clarke, 1992Clarke, , 1999, which facilitates the opportunistic ingestion of larger prey such as amphipods, shrimp, crabs, and even small fish that enter their feeding zone (Lindquist and Kotrschal, 1987). Prey can be taken from the benthos or plankton (Lindquist and Kotrschal, 1987;Clarke, 1999) and for Acanthemblemaria spp., sessile invertebrates are often removed with chisel-like incisors (Kotrschal and Lindquist, 1986). ...
... Species arranged with respect to the amount of detritus algae and sediment in their diet. Data collated from: Goldschmid and Kotrschal (1981); Goldschmid et al. (1984); Kotrschal and Lindquist (1986); Kotrschal and Thomson (1986);Nieder (1997); Muñoz and Ojeda (2000); Depczensky and ; Wilson, unpublished data. dietary resources are limited, selective feeding by fish can be the basis of resource partitioning. ...
... Concurrently, several attempts have been made to quantify the diets of cryptobenthic fishes, but the reported levels of overlap among species have varied extensively. While most studies found separation among cryptobenthic fishes into distinct trophic guilds based on clearly identifiable, broad prey items such as detritus, algae, and copepods (Kotrschal and Thomson 1986;Muñoz and Ojeda 1997;Depczynski and Bellwood 2003;Hernaman et al. 2009), less evidence exists for fine-scale dietary differences among closely related species (Lindquist and Kotrschal 1987;Clarke 1999;Feary et al. 2009). While it is possible that there is little dietary diversification among closely related species, reliable visual identification of prey items from a few milligrams of partially digested, poorly known prey taxa such as micro-invertebrates is difficult and may mask fine-scale differences (Longenecker 2007). ...
... Similarly, unidentified OTUs accounted for 7.2% of sequences (across 8 OTUs) in A. aspera and 32.1% (across 24 OTUs) in A. spinosa's guts. Poorly known taxa such as flatworms are highly diverse but dramatically understudied (Rawlinson 2008), and they have not been identified as important prey taxa in previous investigations of Caribbean blennioids (Lindquist and Kotrschal 1987;Clarke 1992Clarke , 1999. ...
Ecological niches hold critical information concerning the eco-evolutionary dynamics that govern biodiversity and abundance patterns. Cryptobenthic reef fishes account for approximately half of all reef fish species and are an abundant and important group on coral reefs worldwide. Yet, due to their small size and inconspicuous lifestyles, relatively little is known about the ecological niches of most cryptobenthic species. Here, we use gut content DNA metabarcoding to determine dietary niche overlap and prey richness in four sympatric species of cryptobenthic reef fishes in two genera (Acanthemblemaria aspera, A. spinosa, Enneanectes altivelis, and E. matador). Furthermore, we test whether dietary differentiation corresponds with differences in species distribution patterns across twelve sites on the Mesoamerican Barrier Reef in Belize. Our approach reveals dietary partitioning among the four species, which is further supported by low edge density and high modularity in the resulting trophic network. A. spinosa and E. matador consume a significantly higher richness of prey items than their congeners. This result corresponds with non-random distributions and co-occurrence patterns in both species pairs: the two high prey richness species (A. spinosa and E. matador) co-occur more frequently than predicted by chance, but they are exclusive to exposed forereef sites with high wave action. In contrast, their congeners occur across exposed forereef and sheltered backreef sites, but they do not increase in numbers at sheltered sites. Our findings suggest that A. spinosa and E. matador monopolize a wide variety of prey in exposed habitats, but they are unable to meet the energetic demands of their adaptation to high-flow habitats in sheltered areas, possibly due to lower prey availability. This, in turn, indicates strong ecological differentiation among closely related species of cryptobenthic fishes, driven by links between diet, physiology, prey availability, and wave exposure.
... Balanus glandula California, USA O Burger et al. (1980) Oedoparena minor pupae Chthamalus challengeri Hokkaido, Japan O Suwa (1981) Oedoparena spp. larvae and pupaeWashington, USA O Harley & Lopez (2003) Undetermined larvae TUNICATA Herdmania pallida (Heller, 1878)Northeast Brazil F Farrapeira et al. (2010) Microcosmus exasperatus Heller, 1878Northeast Brazil F Farrapeira et al. (2010) PISCES Abudefduf leucozonus ( Bleeker, 1859) Balanus tintinnabulum volcano Pilsbry, 1916 Tanabe Bay, Japan ND Fukao (1980) Acanthemblemaria balanorum Brock, 1940 Balanus tintinnabulum Gulf of California, Mexico O L i n d q u i s t( 1 9 8 5 ) ; Kotrschal & Lindquist (1986) ND Stephens (1963) Acanthemblemaria castroi Stephens & Hobson, 1966 (and eggs) Balanus tintinnabulum Galapagos Islands O Wirtz (1983) Acanthemblemaria castroiB a r r i n g t o n I s l a n d F S t e p h e n s e t a l. ( 1 9 6 6 ) Acanthemblemaria crockeri Beebe & Tee-Van, 1938 Megabalanus californicus ( Pilsbry, 1916) Gulf of California, Mexico F H a s t i n g s( 1 9 8 7 ,1 9 8 8 a ) , 1940 Balanus tintinnabulum Gulf of California, Mexico F L i n d q u i s t( 1 9 8 5 ) Blenniolus brevipinnis (Günther, 1861)Barrington Island ND Stephens et al. (1966) Blennius steindachneri Day, 1873 males (and eggs) Balanus tintinnabulum tintinnabulum Pisbry, 1916 Waltair Coast, India F Raju (1971) Cirripectes sebae (Valenciennes, 1836) young Balanus tintinnabulum volcano Tanabe Bay, Japan ND Fukao (1980) Coralliozetus angelica ( Böhlke & Mead, 1957) (and eggs) ...
The barnacles Tetraclita singaporensis and T. squamosa have a thick test to protect the animals against the diverse environmental stress of the tropical intertidal zone and also against predation by muricid gastropods. After the death of the barnacle, however, the empty test is often taken over by other marine fauna as well as semi-terrestrial animals. The sphaeromatid isopod Dynamenella ptychura was the most abundant inhabitant in empty tests observed in Singapore and Malaysia. Ovigerous crustaceans were common. Gastropod specimens comprised almost entirely juveniles of common intertidal species, including those of the littorinids Littoraria articulata and L. strigata . Gastropod eggs and veligers, insect larvae, pupae and nymphs, and spider spiderlings and immatures were also present. The haminoeid gastropod Smaragdinella was the dominant animal colonizing barnacles in a succession experiment. Temperature was significantly lower inside the empty test than outside, by 0.2°C. Almost 40% of the barnacle tests remained attached to the substratum for more than four months after the death of the individuals.
... There is evidence that these holes limit fish density (Clarke 1989, Buchheim & Hixon 1992. The blennies constantly scan the water and surrounding surfaces for small crustaceans, primarily copepods, which they capture by rapidly darting from their holes for a distance of 1 or 2 body lengths (Greenfield & Greenfield 1982, Lindquist & Kotrschal 1987. Clarke 1992. ...
I monitored the population~ of 2 fishes on a coral reef in St. Croix, U. S. Virgin Islands, from 1980 to 1995 to determine if they could track changes in their habitat. Starting in the mid-1970s. white band disease killed all the elkhorn corals Acropora palmata, providing access to a variety of boring organisms that create the cavities inhabited by the spinyhead blenny Acanthemblemaria spinosa and the roughhead blenny A aspera As the corals became more heavily bored, they were weakened and collapsed, providing more of the low habitat occupied by roughheads and less of the high h a b ~ t a t occupied by spinyheads. This structural change was generally gradual but Hurricane Hugo destroyed almost all the remain~ng standing dead corals in 1989 Both specles increased in density until 1989 when the sudden reduct~on of high habitat caused a decrease in spinyhead population density. In contrast, roughheads continued their population growth until 1991 after which they also declined. Although previous work has shown that spinyheads can displace roughheads from preferred habitat, spinyheads did not increase their numbers close to the reef surface as the high corals collapsed. I hypothesize that their inflexible minimum height is due to their previously demonstrated higher metabolic rate which constrains them to the higher locations where planktonic food is more abundant. Consequently, the species mix shifted from one of spinyheads with extremely rare roughheads in 1980 to one dominated by roughheads w t h few splnyheads in 1995. This precise tracking of a changing environment suggests resource limitation and is counter to the widespread view that coral reef fish assemblages are largely unsaturated systems consisting of open, 1-ecruitment-limited populations. The fishes studied here may be atypical, however, and it is suggested that more studies with a mechanistic approach may prov~de insight into reef fish assemblage structure.
... Following the general consensus among ecologists in the mid-1970s, workers on coral reef fishes assumed that the populations saturated their environments (Smith, 1973;Sale 1974;Smith and Tyler, 1975). Recently, this view has been challenged by investigators who believe that poorly defined factors operating during the planktonic larval stage result in inadequate recruitment to saturate the reef environment (recruitment-limitation hypothesis: Williams, 1980;Robertson et aI., 1981;Doherty, 1983;Victor, 1983;1986;Wellington and Victor, 1985). Evidence exists for both views, but we do not understand the degree to which the unstable reef environment (Connell, 1978;Talbot et aI., 1978;Woodley et aI., 1981;Rogers et aI., 1982;Kaufman, 1983;Walsh, 1983;Lessios et aI., 1984;Glynn, 1985;Wellington and Victor, 1985;Robertson, 1987) contributes to fluctuating carrying capacities which the fish populations may not be able to track with much precision. ...
Two species of hole-dwelling blenny, Acanthemblemaria spinosa and A. aspera, were studied on a coral reef in St. Croix, U.S. Virgin Islands, during two field periods 6 years apart (1980 and 1986) to determine degree of population stability, habitat saturation, and interspecific competition. A. spinosa increased from 1.18 to 1.78 fish · m−2 and A. aspera increased from 0 to 1.37 fish · m−2 for a combined 2.71-fold increase. Both species were abundant in the 5 to 9 m depth range in 1986 but absent from the 1 to 3 m depth range. Transplantation experiments in 1980 indicate that the shallower unoccupied areas are physically suitable for survival and provide adequate food for A. spinosa to persist in a reproductive state for 7 weeks. A. spinosa occupied the higher portions of dead corals in both periods whereas A. aspera occupied the lower portions in 1986, being virtually absent in 1980. Experiments with transplanted fish on artificial habitats indicate that both species prefer the higher portions but A. spinosa excludes A. aspera when they co-occur. Removal of blennies from their natural holes results in 86% of the A. spinosa holes being reoccupied within 2 days whereas the corresponding percentage for A. aspera is 35. It is tentatively concluded that 1980 was an unusual year due to the passage of two hurricanes near St. Croix in the fall of 1979; storms would disproportionately depress A. aspera because it shelters close to the bottom. It is argued that in the case of spatially-clustered organisms, strong intraspecific competition can occur in an unsaturated environment, but whether or not this also applies to interspecific competition is unclear.
... Although common and often conspicuous, relatively little work has been done on the ecology and behavior of chaenopsids. Niche (diet and shelter hole) partitioning has been examined experimentally and in the field for a few, site-attached species of Acanthemblemaria by Lindquist (1985), Kotrschal and Lindquist (1986), Lindquist and Kotrschal (1987) and Clarke (1989), and general notes on the distribution and ecology of chaenopsids off Central America are reported by Greenfield and Johnson (1981). The only major study to examine the behavior of the animals is that by Lindquist (1975), which is primarily an ethological analysis of the motor patterns used in social interactions. ...
Patterns of space use and defence by the pikeblenny, Chaenopsis alepidota, were studied over a 13-month period in 1977-1978 for a population inhabiting a sand/rubble plain in a small bay along the Baja California coast of the Sea of Cortez, The abundance of C. alepidota varied widely over the year, as did its apparent mobility and territorial behavior. Analysis of size-frequency distributions suggests that in part the change in abundance reflects recruitment and rapid growth of a species that is largely annual. During periods of low population density, resources appeared to be abundant and individuals appeared to roam widely and were largely non-aggressive, whereas during a period of high density, resources appeared to be in shorter supply, individuals were more site-attached and the incidence of agonistic interactions increased markedly. The apparent short generation time of the species suggests population densities vary widely among habitats and years (reflecting recruitment variability), with concomitant shifts in a labile social system. The emphasis in the literature on vigorous territoriality in pikeblennies may reflect a bias due to their conspicuousness during periods of high population density.
... Fishes possess many sophisticated sensory systems including vision, hearing, and a lateral line. The spinyhead blenny, Acanthemblemaria spinosa, has been referred to as a hemisessile organism, living within crevices of coral skeletons (Kotrschal and Lindquist 1986; Clarke 1992). Because the blenny visually detects its prey, the color, size, and motion of the prey item should signiWcantly aVect the prey's chance of survival. ...
Calanoid copepods typically exhibit escape reactions to hydrodynamic stimuli such as those generated by the approach of a
predator. During the summers of 2000, 2001 and 2004, two small calanoid species, Temora turbinata Dana, 1849 and Paracalanus parvus Claus, 1863 were exposed to a visual predatory fish, the blenny Acanthemblemaria spinosa Metzelaar, 1919, and their predator–prey interactions were recorded using both high-speed and standard videographic techniques.
Copepod escape reaction components, including swimming pattern, reactive distance, turning rate, and jump kinetics, were quantified
from individual predation events using motion analysis techniques. Among the observed escape reaction components, differences
were noted between the species’ swimming patterns prior to attack and their response latencies. Temora turbinata was a continuous cruiser and P. parvus exhibited a hop-and-sink swimming pattern. During periods of sinking, P. parvus stopped beating its appendages, which presumably reduced any self-generated hydrodynamic signals and increased perceptual
abilities to detect an approaching predator. Response latency was determined for each copepod species using a hydrodynamic
stimulus produced by a 1ms acoustic signal. Response latencies of T. turbinata were significantly longer than those of P. parvus. Despite some apparent perceptual advantages of P. parvus, the blenny successfully captured both species by modifying its attack behavior for the targeted prey.
... The significantly greater proportion of backward strikes by A. aspera could be related its normally feeding on harpacticoid copepods (Clarke 1999). These benthic organisms, while ''...relatively easy to catch (if you're a fish!)'' (Hicks and Coull 1983), would require great flexibility on the part of a ''hemisessile'' (Kotrschal and Lindquist 1986) fish. Whereas free-swimming fish can orient their whole bodies towards harpacticoids as they pick them off surfaces, and plankton-eating A. spinosa can choose the location to strike as prey are carried past them, A. aspera must be able to bend sideways and backwards to pick harpacticoids off surfaces in the vicinity of the shelter hole. ...
Water motion is an important factor affecting planktivory on coral reefs. The feeding behavior of two species of tube-dwelling coral reef fish (Chaenopsidae) was studied in still and turbulent water. One species of blenny, Acanthemblemaria spinosa , lives in holes higher above the reef surface and feeds mainly on calanoid copepods, while a second, A. aspera , lives closer to the reef surface, feeds mainly on harpacticoid copepods, and is exposed to less water motion than the first. In the laboratory, these two blenny species were video recorded attacking a calanoid copepod ( Acartia tonsa, evasive prey) and an anostracan branchiopod (nauplii of Artemia sp., passive prey). Whereas A. spinosa attacked with the same vigor in still and turbulent water, A. aspera modulated its attack with a more deliberate strike under still conditions than turbulent conditions. For both fish species combined, mean capture success when feeding on Artemia sp. was 100% in still water and dropped to 78% in turbulent water. In contrast, when feeding on Acartia tonsa, mean capture success was 21% in still water and rose to 56% in turbulent water. We hypothesize that, although turbulence reduces capture success by adding erratic movement to Artemia sp. (passive prey), it increases capture success of Acartia tonsa (evasive prey) by interfering with the hydrodynamic sensing of the approaching predator. These opposite effects of water motion increase the complexity of the predator-prey relationship as water motion varies spatially and temporally on structurally complex coral reefs. Some observations were consistent with A. aspera living in a lower energy benthic boundary layer as compared with A. spinosa: slower initial approach to prey, attack speeds modulated according to water velocity, and lower proportion of approaches that result in strikes in turbulent water.
... Consequently, they are very different from the pomacentrids so often used in population and community studies of coral reef fishes. Fishes of this genus live in small holes in hard substrate (Lindquist 1985) where they spend most of their active time visually scanning the surrounding water and substrate for small invertebrates which serve as their food (Greenfield and Greenfield 1982;Lindquist and Kotrschal 1987). On spotting a prey item, a blenny will dart from its shelter, grasp the prey, and rapidly reenter its shelter tail first. ...
Spinyhead blennies (Acanthemblemaria spinosa) and roughhead blennies (A. aspera) are planktivorous hole-dwelling fishes that live in dead coral skeletons. Both species are known to choose shelters high above the reef surface (although spinyheads displace roughheads downwards). To test the hypothesis that this preference is due to greater plankton availability in higher locations, fish were placed on artificial habitats located 15 cm and 100 cm above the surface of a natural reef. Both species experienced higher feeding rates, growth rates, and fecundities in high locations, and spinyhead rates generally exceeded roughhead rates at a given height. Under laboratory conditions, oxygen consumption by spinyheads was 1.6 times greater than that of roughheads and this corresponds well with the 1.8 ratio of feeding rates under controlled aquarium conditions. This information provides a partial explanation for the observed microhabitat distribution and resulting coexistence of these competing species: it is hypothesized that spinyheads have an advantage in agonistic interactions because of their higher metabolic rates, thus excluding roughheads from high sites, but that roughheads can persist at low sites because their lower metabolic rates result in lower food demands. A model is presented that predicts varying occurrences and vertical distributions of these species in locations with different zooplankton densities.
... Chaenopsid blennies are inconspicuous but frequently abundant members of the benthic community. Members of the genus Acanthemblemaria are among the most closely tied to the substrate, to the point of being called hemisessile (Kotrschal and Lindquist 1986). They reach densities of 5 fish m -2 over large reef areas (Clarke 1996) and can achieve local densities as high as 60 fish m -2 (Lindquist 1985). ...
The chaenopsid blenny Acanthemblemaria spinosa occupies topographically high locations on coral reefs where flow speeds and turbulence are frequently greater than those
experienced by its congener, A. aspera, which occupies locations close to the reef surface. To investigate the adaptive mechanisms resulting in this microhabitat
differentiation, the foraging effort and success of these fishes were determined in laboratory flumes that produced flow conditions
approximating those experienced in the field. Individual fish were subjected to unidirectional (smooth and turbulent) and
oscillatory flows while they fed on calanoid copepods, Acartia tonsa, whose vulnerability to predation varies with water flow. In unidirectional flow both blenny species had their greatest foraging
success at intermediate flow speeds (ca. 10cms−1) and under turbulent flow. Under all conditions, Acanthemblemaria spinosa exhibited greater foraging effort and attacked at greater distances, greater mean water speeds, and in oscillatory flow,
over a greater proportion of the wave cycle than did A. aspera. A. spinosa also exhibited greater foraging success under turbulent flow conditions. These differences in feeding patterns allow A. spinosa, with its higher metabolic rate, to occupy the more energetic higher locations in corals where planktonic food is more abundant.
A. aspera occupies the poorer quality habitat in terms of planktonic food availability but its lower metabolic rate allows it to thrive
there. Consequently, these species divide the resource in short supply, i.e., shelter holes, based on their differing abilities
to capture prey in energetic water conditions in conjunction with their differing food energy requirements.
... Skull morphology does not appear to be important in feeding behavior, nor does it influence predation success (Clarke et al., , 2005Finelli et al., 2009). There may be selection for skulls that efficiently block the blenny shelters as a means of defense against predators (Lindquist and Kotrschal, 1987). Defense against conspecifics seems more likely, as shelters may be limiting (Hastings and Galland, 2010) and A. spinosa individuals can use the head spines to wedge Table 4 (A-D) The list of characters found which support or conflict with the placement of A. spinosa and A. medusa in the morphological phylogeny. ...
Neotropical reef fish communities are species-poor compared to those of the Indo-West Pacific. An exception to that pattern is the blenny clade Chaenopsidae, one of only three rocky and coral reef fish families largely endemic to the Neotropics. Within the chaenopsids, the genus Acanthemblemaria is the most species-rich and is characterized by elaborate spinous processes on the skull. Here we construct a species tree using five nuclear markers and compare the results to those from Bayesian and parsimony phylogenetic analyses of 60 morphological characters. The sequence-based species tree conflicted with the morphological phylogenies for Acanthemblemaria, primarily due to the convergence of a suite of characters describing the distribution of spines on the head. However, we were able to resolve some of these conflicts by performing phylogenetic analyses on suites of characters not associated with head spines. By using the species tree as a guide, we used a quantitative method to identify suites of correlated morphological characters that, together, produce the distinctive skull phenotypes found in these fishes. A time calibrated phylogeny with nearly complete taxon sampling provided divergence time estimates that recovered a mid-Miocene origin for the genus, with a temporally and geographically complex pattern of speciation both before and after the closure of the Isthmus of Panama. Some sister taxa are broadly sympatric, but many occur in allopatry. The ability to infer the geography of speciation in Acanthemblemaria is complicated by extinctions, incomplete knowledge of their present geographic ranges and by wide-spread taxa that likely represent cryptic species complexes.
Cryptobenthic reef fish (PACB) are a highly diverse and abundant group characterized by fish with an adult body size < 5 cm and a strong association with the benthos. Despite their ecological importance, this group has been poorly studied, and how these fish respond to the three-dimensional structure and habitat complexity (CH) of the benthic environment remains unknown. The objective of this study was to estimate CH through photogrammetric modeling of 3D rugosity and assess relationships with PACB assemblages in three rocky-coral reefs sites in the Eastern Tropical Pacific. Positive and significant relationships between CH and biological variables were found, demonstrating the importance of habitat three-dimensionality for PACB assemblages. However, these relationships were weak and variable and depended greatly on spatial scale and region. Species richness, abundance, and biomass of PACB were significantly correlated to diverse types of benthic cover, but contrary to expectations, coral cover was negatively correlated with PACB richness and abundance. Conversely, rocky substrate was positively correlated with richness, abundance, and biomass, although these results varied depending on the study region. Significant differences were found in biological variables among different microhabitats. Contrary to expectations, significantly higher values were observed in microhabitats composed of rock and massive corals, while the lowest values were observed in branched corals for all biological variables. Differences between regions were evident; however, no clear latitudinal pattern was observed in terms of richness, abundance, and biomass. The findings of this study contribute to the understanding of PACB and serve as a baseline for evaluating responses to future changes in CH.
Molecular analysis of the chaenopsid tube blenny, Acanthemblemaria macrospilus Brock, reveals species-level differentiation and the existence of a new species, described here as Acanthemblemaria hastingsi, using molecular and morphological data. This new species is a member of the hancocki species group and is limited to the Gulf of California. It is distinguishable from A. macrospilus by mitochondrial gene sequences of cytochrome C oxidase I and D-loop region as well as by coloration. This differentiation is also supported to a lesser extent by the nuclear ribosomal protein S7 first intron. There is no geographic overlap in the ranges of these species, as they occur exclusively on either side of the Sinaloan Gap.
Spinyhead blennies occupy abandoned worm holes in coral heads on Caribbean reefs. We conducted a series of short-duration field experiments off St. Thomas, US Virgin Islands, which indicated that such holes are a limiting resource and that larger fish competitively dominate smaller fish for access to holes. Few fish that were added to coral heads lacking vacant holes were able to secure holes, and did so only by displacing larger residents after severe combat. However, when vacant holes were added to coral heads before adding fish, transplanted fish readily occupied the new holes. When holes were added to coral heads without also adding fish, the new holes were colonized by immigrants from the surrounding habitat. Similarly, when resident fish were removed from coral heads, the emptied holes were colonized. Immigrants were smaller than removed residents, and, in cases where resident fish changed holes following removals of neighbors, they moved to sites previously occupied by larger fish. Fish displaced up to 5 m returned to their original holes, consistent with the possibility that spinyhead blennies may occasionally leave their holes and search for sites of better quality. We conclude that intraspecific competition for shelter holes may limit the number of spinyhead blennies occupying a coral head.
In order to determine the extent to which tube blennies depend on food derived from within or outside of the reef system, the diets of Acanthemblemaria spinosa, A. aspera, A. greenfieldi and A. paula were compared with food availability using plankton, benthic and gut sampling. All species fed primarily on copepods, but A. spinosa consumed calanoids and cyclopoids of planktonic origin whereas the other species consumed harpacticoids of benthic origin. This pattern correlates with the occurrence of A. spinosa in tall corals whereas the other species are found in corals close to the reef surface. Calanoids were more abundant 1 m above the reef surface than <0.5 m above the reef surface. Oxygen consumption rates were determined for the above species and Emblemariopsis pricei and E. ruetzleri. On the oxygen consumption versus body weight graph, A. spinosa shares a high slope with the Emblemariopsis species, which was three times greater than the slopes of other species of Acanthemblemaria. It is not known if the high metabolic rate of A. spinosa is a consequence of the greater food availability in its microhabitat, an adaptation for acquiring the higher quality microhabitat, or both. In any case, A. spinosa is the only Acanthemblemaria species in this study that imports nutrients to the reef by consuming plankton.
Skulls and jaws are compared in 35 species of tropical eastern Pacific (mainly Gulf of California) blennioid fishes (5 species of Tripterygiidae, 13 Labrisomidae, 12 Chaenopsidae, 5 Blenniidae). Morphotypes are arranged in a series from relatively large-mouthed fishes (tripterygiids and a few labrisomids) with protrusible jaws and conical teeth to species with small, non-protrusible jaws and a single row of incisiform teeth. This polarity of arrangement probably reflects the direction of phylogenetic development, as suggested by outgroup comparison with other perciform fishes. Distribution patterns of morphotypes in a simple morphospace, obtained by combining dentition, shape of the jaw arch and jaw protrusibility, are discussed within an adaptive context.
Gut contents of a total of 180 specimens of the blennies Scartella cristata (L., 1758). Parablennius pilicornis (Cuvier, 1829) and Lipophrys trigloides (Valenciennes, 1836) caught in the course of 1990 off Playa de la Mora (Prov. Tarragona, Spain) were analysed. The quantitative composition of food differed considerably between the 3 species (mostly algae in the herbivorous S. cristara. Amphipoda in the carnivorous L. trigloides and a variety of items in omnivorous P. pilicornis). The 3 species in the course of a year overlap little in food resource use, with overlap reaching its maximum in April when juvenile Mytilus on the rock substrate are in ample supply. In S. cristata and L. trigloides, diversity of food items is similarly lowest in July and April, respectively, when these 2 species attain their optimal nutritional status. In contrast, diet diversity and food intake are inversely correlated in P. pilicornis. Evidently, resource sharing between blenniid species in the rocky shore habitat is clearly structured, but subject to seasonal dynamics. It is concluded that food niche analyses should consider seasonal plasticity in feeding patterns and refrain from premature conclusions based on short-term studies.
The ecomorphological relationships between the oral jaws and food spectra were highlighted in 34 species of Gulf of California
blennioid fishes (5 Tripterygiidae, 13 Labrisomidae, 11 Chaenopsidae and 5 Blenniidae). Twenty-nine species are microcarnivorous,
two are omnivorous browsers, two are algae grazers and one was an ‘ectoparasite’ feeder. The spectrum of oral (as opposed
to pharyngeal) jaw (OJA) morphology ranges from plesiomorphic, suction-feeding (relatively large, protrusible jaws, with many
coniform-caniniform teeth) to apomorphic, biting (relatively small, non protrusible jaws, with a single row of incisiform
teeth). As species with similar morphology may widely differ in food, it is concluded, that morphology is not a reliable predictor
for ecology in this case. With the exception of a few specialists, species with apomorphic, biting OJA utilize sessile items
in addition to mobile categories and thus show a higher food diversity as compared to species with plesiomorphic OJA. Thus in the present
case morphological differentiation goes along with ecological generalization. Only three blenniid species with the most apomorphic
OJA may be considered as specialized also with regard to food resource utilization. Transformation of morphological characters
and the ecological role of the OJA of blennioids may serve as a model to illustrate the steps required to achieve a biting-browsing
and grazing feeding apparatus in many taxa of modern acanthopterygian reef fishes.
Peptic ulcer bleeding is a serious medical problem with significant morbidity and mortality. Endoscopic therapy significantly reduces further bleeding, surgery and mortality in patients with bleeding peptic ulcers and is now recommended as the first hemostatic modality for these patients. The efficacy of large-dose proton pump inhibitor (PPI) therapy in reducing re-bleeding after endoscopic therapy has been supported by evidence derived from randomized controlled trials. It may be premature to recommend small-dose intravenous injection PPI after endoscopic hemostasis in patients with bleeding ulcers. An updated systematic review shows that PPI therapy before endoscopy significantly reduces the proportion with major stigmata and requirement for endoscopic therapy at index endoscopy. Some studies show that there is no significant difference between oral and intravenous PPIs in raising intragastric pH. However, clinical data is lacking in patients with peptic ulcer bleeding to date.
The vertical distribution of nine species of combtooth blennies between the surface and 1,5 m depth was studied at selected rocky shore sections of the Mediterranean Sea in NE Spain and the W coast of Italy. Significant differences in mean depths of sojourn and the degree of depth overlap allow the distinction of species subgroups: species preferring the uppermost shore (Coryphoblennius galerita, Aidablennius sphynx and Lipophrys trigloides), those mostly found in a middle stratum (Lipophrys canevai, Scartella cristata, Parablennius incognitus, Parablennius gattorugine) and two species with the lowest depth of sojourn (Parablennius pilicornis, Parablennius zvonimir). The relative depth position showed little seasonal variation and was similar at both Spanish and ltalian sites. The species of each subgroup which shows a high degree of spatial overlap is distinguished in other dimensions of its ecological niches, in particular by different feeding habits and differences in shelter characteristics. On the basis of exact depth distribution data the present study indicates that depth differences of Mediterranean blennies are very finely tuned and species-specific, even on a broad geographical and seasonal scale. Key words: Vertical zonation, Rocky shore, Ecological niches, Overlap, Microhabitat, Fish assemblage
The relationships of the red and melanic color phases of the browncheek blenny, Acanthemblemaria crockeri, are examined. Pure populations of the red phase occur near the heads of the San Lucas and Los Frailes submarine canyons. Introgressive populations of the two phases occur together in a zone of sympatry from Los Frailes to at least Guaymas (central Gulf of California), where the red phase is limited almost completely to females that vary from pure red to intermediate (combination of the red and melanic phases). These red and intermediate females are both less abundant and decreasingly red as one goes north in the zone of sympatry. All males in the zone of sympatry are of the melanic phase and the proportion of melanic phase females increases abruptly in central gulf populations. The distribution pattern suggests: 1) the pure red phase populations of the cape region of Baja California probably developed as an insular population where red can be adaptive in these deeper submarine canyon populations; 2) these pure red phase populations may be homozygous for the red allele; 3) red phase males are not fit north of the cape region either because nonmelanic males cannot attract females (melanic color is important in sexual displays) or because red is obvious and red individuals are removed by predators or a combination of both; and 4) the intermediate phase females are maintained in central gulf populations because of selection for increased sexual dichromatism. Unfortunately, these suggestions do not, at present, adequately explain the odd sex-related distribution of individuals in the zone of sympatry.
A new member of the "hancocki" species complex, Acanthemblemaria castroi, is described from the Galapagos Islands. A new species, Coralliozetus springeri, is described from the Pacific coast of Panama, forming a geminate pair with C. cardonae from the Caribbean Sea. The description of the latter species is supplemented as is that of Chaenopsis schmitti Böhlke. The ranges of three species are extended: Coralliozetus boehlkei Stephens to Cocos Island, Coralliozetus angelica (Böhlke and Mead) to Socorro Island, the Revillagigedos, and Acanthemblemaria balanorum Brock to Bahia Piñas, Panama. Meristic variation with latitude, size reduction in the Cocos Island population, and reproductive behavior are described for Acanthemblemaria macrospilus Brock.
1. The various commonly used methods of assessing, on the basis of gut contents, the food of those fishes which have a generalized diet are listed and discussed. Both during the present investigation and by re-examination of published data it is shown that, when a large number of fish are examined, and when the results are expressed comparably, i.e. each food item is shown as a percentage of the total food eaten, all methods give substantially the same results. Reasons are, however, given for rejection of the method based on the number of organisms eaten, and also of the practice of comparing data so obtained with counts of the organisms found in samples of small areas of the substratum. Such comparisons have in the past been used to give numerical expression to the availability of food organisms; but it is suggested that this would be better accomplished by using an arbitrary method of allocation of points on the basis of estimated volume of each food item present (a) in the fish guts, and (b) in general faunal collections from the habitat. The number of points, expressed as a percentage of the total, gained by any food item in the fish guts and in the general collections could then be compared. 2. The food of Gasterosteus aculeatus is studied, and it is shown that the diet, consisting chiefly of Crustacea and insects, changes slightly with season and with increase in size of fish. During the winter the fish eat less than at other times, and both sexes feed more sporadically than usual during the breeding season. It is suggested that the two biological races, A and B of Heuts, have different diets. 3. The food of Pygosteus pungitius is shown to be similar to that of Gasterosteus aculeatus, and to vary similarly. The data for the winter are, however, incomplete, and it appears that feeding in this species is more affected during the breeding season. 4. The food relations of three species of fish (G. aculeatus, Pygosteus pungitius and Rutilus rutilus) in a a small muddy Cheshire stream are discussed. It is shown that R. rutilus does not compete with the two other species, but that the diets of the two stickleback species are almost identical. It is suggested that differences in breeding habits enable these two species to live together as they nest in different areas, and that the number of each species is regulated by the fact that during the breeding season the males defend a definite territory round their nests. There is therefore only room for a certain number of nests of each species.
Objective, empirical measures of overlap between samples of items distributed proportionally into various qualitative categories are presented and reviewed. These indices of overlap, derived from either probability or information theory, should prove useful to the ecologist in comparative studies of diet, habitat preference, seasonal patterns of abundance, faunal lists, or similar data.
In this study I review the literature on resource partitioning in fish assemblages from 1940-83. Studies are grouped into seven global habitats: tropical reefs, temperate reefs, coastal marine, the Antarctic, mesopelagic/slope environments and freshwater streams and lakes. Freshwater systems first attracted the interest of resource ecologists; however, the number of studies of assemblages in all global habitats has risen sharply in the last decade. Studies treating single fish families show that resource partitioning occurs along more resource axes in more diverse assemblages. Unlike terrestrial systems, trophic separation is more important than habitat separation in fish assemblages. Based on 37 studies which concurrently examined habitat, food and temporal axes, 32% showed primary separation by habitat, 57% showed the greatest separation by food and 11% showed temporal separation to be most important. Global habitat differences in the importance of major resource axes are difficult to determine because of sampling bias; however, fish assemblages in most habitats show approximately equal importance of separation along spatial and trophic dimensions. The exceptions are marine systems, especially temperate marine reef assemblages which show greater importance of trophic separation. Global habitat differences in the amount of resource partitioning are not apparent, given the level of resolution of this study. Assemblages from all habitats show rather high separation of coexisting species along at least one resource dimension. The degree of taxonomic relatedness varies significantly over assemblages from the seven major global habitats. Investigation of tropical reef fish assemblages and also stream fish assemblages, has focused on more closely related faunas than studies of assemblages from other habitats. The degree of relatedness has a significant effect on ecological separation for both congeneric-confamilial and confamilial-conordinal species pairs, with less related pairs showing greater differences in resource use. Comparisons of niche overlap between assemblages of different taxonomic structure will thus be biased by historical effects. Unlike habitat or trophic partitioning, temporal partitioning was significantly more important in less related species pairs so that temporal partitioning, at least to a major degree, may reflect historical effects, rather than coevolution within a particular community. Few studies have attempted to deal with most or all life history stages of species in an assemblage so that our knowledge of resource partitioning is biased toward late juvenile to adult stages. The inclusion of more life history stages, the control (or awareness) of biases due to historical effects or sampling design and a more experimental approach will be important components of future studies of resource partitioning.
Eight epiphytal samples were taken from the upper littoral at Banyuls-sur-Mer (French Mediterranean coast) and the fauna living on the thalli of algae or between bivalves was examined. Intestinal food contents of 67 specimens of 5 Blennius species (B. trigloides, B. canevae, B. sphinx, B. incognitus, and B. dalmatinus) occurring in the same biotope were also investigated. The epiphytal samples consisted of a rich supply of amphipods, bivalves, and algae. Amphipods are the preferred food of the Blennius species examined. These fishes also consume large amounts of copepods and algae, and small quantities of halacarids, bivalves, and ostracods. In addition to serving as a substrate for the main food-animals of the fishes, the algae themselves constitute an important food source. Presumably, for these reasons, the fishes remain close to the area inhabited by the algae on rocky substrates.
In terms of species number (47) and numerical abundance, blennioids are the most important primary resident rocky reef fishes in the Gulf of California, Mexico. We present the feeding patterns of the 34 most abundant species of blennioid fishes, 8 of which are Gulf endemics. A total of 2,144 specimens were sampled at 51 anaesthetic stations in 9 areas throughout the Gulf. Four feeding guilds were distinguished: 1) The majority (29 of 34 species) are microcarnivores exhibiting a number of different feeding strategies (ambush and stalking predators, active foragers, pickers, etc.). The more important prey categories were mobile invertebrates, and to some extent also sedentary fauna. Algae were of no importance for most of the latter species. 2) Hypsoblennius brevipinnis and H. gentilis are two omnivorous species, browsing mainly on sessile items including 52% and 13% (Vol.) algae in their diets. 3) Entomacrodus chiostictus and Ophioblennius steindachneri are herbivores, grazing on fine algae. 4) Plagiotremus azaleus specializes in cropping mucus and scales from the body surface of other fishes.Crustaceans account for 58.6% of the total volume of prey items in the 34 species investigated. Benthic amphipods were most important and made up 26% of the total volume of all prey items.Cluster analysis of percentage volumetric data using Squared Euclidian Distance and Horn's Index of Overlap produced distinct subgroups which coarsely reflected taxonomic grouping.The species are separated either by their geographic ranges, habitat and microhabitat preferences, feeding, or a combination thereof. Only rarely do sympatric species significantly overlap in diet.Trophic diversity as measured by the Shannon-index provides a tool for distinguishing: 1) specialists (6 species) from 2) low diversity feeders (18 species) and 3) high diversity generalists (10 species). Two different types of specialists can be distinguished: those which feed on the same items as the generalists but utilize only a very restricted prey spectrum (Stathmonotus sinuscalifornici and the chaenopsids Chaenopsis alepidota and Emblemaria hypacanthus). A second group of specialists (Entomacrodus chiostictus and Ophioblennius steindachneri as well as Plagiotremus azaleus) feed on items not utilized by any of the generalists.There is some evidence that high diversity generalists are numerically more abundant than the other trophic groups.In the labrisomids and blenniids a phylogenetic trend from microcarnivory towards feeding on sessile items appears to be expressed.
Twelve species of the fish genusBlennius (Blennioidei, Perciformes) have been investigated with regard to their ecological requirements at 20 distinct localities of the western and southern Mediterranean Sea. The species examined respond differently to the environmental factors temperature, light, salinity, and wave-action.Blennius cristatus is a thermophil species, whereasB. dalmatinus may be thermophobe.B. sanguinolentus, B. pavo, B. sphinx, andB. dalmatinus prefer habitats exposed to the sunlight;B. gattorugine andB. zvonimiri inhabit shadow biotopes. One can findB. galerita, B. trigloides, andB. cristatus at the surf-stage normally, whereasB. sphinx, B. canevae, andB. gattorugine are facultative inhabitants of this biotope. The vertical distribution depends on wave-action and, in part, on light. The main escape direction is upward to the water surface by most species inhabiting the surf-stage, downward byB. gattorugine andB. zvonimiri, and laterally by the other species examined. Morphological adaptations to the habitat in the surf-stage are indicated by the round or slightly depressed form of the body, and by the strong rays of the pectoral, pelvic and anal fins. None of theBlennius species examined exhibits ecological requirements similar to those of another species. It is probable that the striking specific radiation of the genusBlennius is rendered possible by the availability of different biotopes and microclimates.
Thesis (Ph. D.)--University of Arizona, 1975. Includes bibliographical references (leaves 141-147). Photocopy of typescript. 28 cm.
Thesis (Ph. D.)--University of California, Los Angeles-Zoology. Typewritten.
Reef fishes of the Sea of Cortez The reproductive behavior of three blennioid fish endemic to the Galapagos Islands
- D A Thomson
- L T Findley
- A N Kerstitch
THOMSON, D. A,, L. T. FINDLEY & A. N. KERSTITCH, 1979: Reef fishes of the Sea of Cortez. J. Wiley and Sons, N.Y.; 302pp. WIRTZ, P., 1983: The reproductive behavior of three blennioid fish endemic to the Galapagos Islands. Noticias de Galapagos, 37: 26-27.
Habitat and resource partitioning between two species ofAcanthemblemariawith comments on the chaos hypothesis The Atlantic barrier reef ecosystem at Carrie Bow Cay
- D W Greenfield
- T A Greenfield
- K Rutzler
- I G Macintyre
Habitat and resource partitioning between two species of with comments on the chaos hypothesis
Notes on the behavior, ecology and distribution of Lucayablennius zingaro.
- Colin P. L.
Food preferences, morphology and arrangement of teeth in 14 species of Adriatic blennies
- Kotrschal K.
Meandrina meandrites and Emblemariopsis diaphana, first record of an association between a stony coral and a fish, similar to anemone fish relationship.
- Butter M. E.