Browsing by Author "CANCINO, JM"

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    EFFECT OF ENCRUSTING BRYOZOANS ON THE PHYSIOLOGY OF THEIR ALGAL SUBSTRATUM
    (1991) MUNOZ, J; CANCINO, JM; MOLINA, MX
    Traditionally, colonies of encrusting epiphytic bryozoans have been regarded as biotic factors reducing photosynthetic performance in benthic algae. In this study we determined under laboratory conditions the effects of Membranipora tuberculata on the photosynthetic efficiency of the rhodophyte Gelidium rex.
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    EFFECTS OF THE BRYOZOAN MEMBRANIPORA-TUBERCULATA (BOSC) ON THE PHOTOSYNTHESIS AND GROWTH OF GELIDIUM-REX SANTELICES ET ABBOTT
    (1987) CANCINO, JM; MUNOZ, J; MUNOZ, M; ORELLANA, MC
    Several species of Membranipora commonly occur on brown and red algae. It is currently believed that these bryozoans could affect growth of the host plant by modifying incident light. In the present study, we report on the changes that occur in both intensity and quality of light passing through colonies of M. tuberculata (Bosc.) and on the effects of bryozoans on growth of the host plant. M. tuberculata decreases photon-flux density by up to 56% of the incident light and slightly affects the quality of the incident light. Although the bryozoan reduces the photosynthetic rate of Gelidium rex Santelices et Abbott, it does not have a net effect on algal growth. It is concluded that the effects of epifauna on algal growth depend on the nature of the algal structure colonized. Therefore, it cannot be predicted a priori that encrusted thalli should grow at a slower rate than nonencrusted thalli.
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    EMERSION BEHAVIOR AND FORAGING ECOLOGY OF THE COMMON CHILEAN CLINGFISH SICYASES-SANGUINEUS (PISCES, GOBIESOCIDAE)
    (1988) CANCINO, JM; CASTILLA, JC
    The present study is the first to correlate information on emersion behaviour and foraging ecology of Sicyases sanguineus, a common clingfish of the Chilean coast. Individuals smaller than 15 cm in total length were frequently found at the highest points in the inter-tidal zone and consumed inter-tidal animals and seaweeds. Fish larger than 23 cm were infrequently observed emersed in the lower inter-tidal zone, but were collected sub-tidally by divers. These large clingfish ate mainly benthic animals occurring in the low inter-tidal and sub-tidal zones. Size-dependent factors, dessication and wave impact restrict the area of action of S. sanguineus to certain areas of the rock inter-tidal and shallow sub-tidal zone. However, the fish can be locally very abundant, consuming a great diversity of prey items including both direct primary space users and mobile animals able to affect community structure through grazing. We argue, therefore, that S. sanguineus may be important in structuring communities in some areas of the rocky inter-tidal and shallow sub-tidal zones of Central Chile.
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    ENVIRONMENTAL CUES AND THE PHASING OF LARVAL RELEASE IN THE BRYOZOAN CELLEPORELLA-HYALINA (L)
    (1991) CANCINO, JM; HUGHES, RN; RAMIREZ, C
    Celleporella hyalina broods lecithotrophic larvae that are pelagic for a few hours after release. Colonies of this bryozoan were placed in chambers suspended in the sea. Pre-filtered, ambient water, continuously pumped through the chambers, was delivered into sieves on a fractionator, partitioning the output into hourly samples. Larvae retained by the sieves were counted under a low-power microscope.
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    ONTOGENIC CHANGE IN THE DIET OF APLODACTYLUS-PUNCTATUS (PISCES, APLODACTYLIDAE) - AN ECOPHYSIOLOGICAL EXPLANATION
    (1994) BENAVIDES, AG; CANCINO, JM; OJEDA, FP
    Aplodactylus punctatus is a temperate herbivorous fish that changes from an omnivorous to a herbivorous diet and increases its ability to assimilate algae as it grows. To investigate whether this dietary shift is related to size-specific differences in energetic demands imposed by metabolism and the amount of assimilated energy, oxygen consumption (V(O2)) was determined experimentally in 12 specimens ranging in size from 62 to 545 g. V(O2) increased allometrically with body size from 8.41 to 55.95 mg O2 individual-1 h-1. Individual energetic requirements were 2.8 to 33.7 kJ d-1. The assimilated energy was estimated, taking into consideration: (1) the energetic value of the most important alga in the diet (Lessonia trabeculata); (2) size-specific differences in assimilation rates for fish fed on this alga; (3) size-specific differences in throughput time and in the amount of food in a full gut. Comparison of the energy required and the assimilated energy revealed that fishes of < 22 to 29 cm total length had a negative energetic balance when consuming algae exclusively. This may explain the reliance of small A. punctatus on more easily-digested invertebrates. The largest individuals can meet their energetic demands by consuming algae alone, apparently because of their higher assimilation capability. In A. punctatus, changing energetic requirements and capacities for algal assimilation may be responsible for the observed ontogenetic change in diet.
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    ONTOGENIC CHANGES IN GUT DIMENSIONS AND MACROALGAL DIGESTIBILITY IN THE MARINE HERBIVOROUS FISH, APLODACTYLUS-PUNCTATUS
    (1994) BENAVIDES, AG; CANCINO, JM; OJEDA, FP
    1. Even though herbivorous fish have longer digestive tracts than carnivorous fish, a fact which agrees with optimal digestion theory, the existence of a relation between relative length of the digestive tract and capacity to digest and assimilate algal material has not been experimentally demonstrated. 2. We tested whether an increase in gut dimensions during ontogeny was associated with an increase in capability of fish to digest macroalgae in Aplodactylus punctatus. 3. Total gut length of this temperate marine fish increased from 43 to 237 cm as body length increased from 22 to 42 cm total length (TL). 4. Macroalgae, mainly fronds of the brown kelp Lessonia trabeculata, were the principal item found in their guts. 5. Individuals smaller than 30 cm had a higher proportion of invertebrate biomass in their gut than larger fish (40.6% and 0.3% of total content, respectively). 6. Transit time for Lessonia fronds increased as a function of body size, ranging between 20 h in fish 26.6 cm TL and 52 h in 40.0 cm fish. 7. Apparent digestibility of organic matter and total nitrogen increased as a function of body size from 38% to 80% when feeding on a Lessonia diet, and from 57% to 96% on a Ulva sp. diet. 8. These results explain why small herbivorous fish need to consume animal prey to satisfy their high mass-specific protein demands. 9. This study constitutes the first experimental demonstration in fish that an increase in relative gut length is associated with an increase in the capability to digest macroalgae. This allows larger fish to meet their energetic demands by consuming algae owing to their capability to digest low-quality food.