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  • 1
    Electronic Resource
    Electronic Resource
    MUTUALISMS AND AQUATIC COMMUNITY STRUCTURE: The Enemy of My Enemy Is My Friend (2004)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Ecology, Evolution, and Systematics 35 (2004), S. 175-197 
    Details
    ISSN: 1543-592X
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology
    Notes: Mutualisms occur when interactions between species produce reciprocal benefits. However, the outcome of these interactions frequently shifts from positive, to neutral, to negative, depending on the environmental and community context, and indirect effects commonly produce unexpected mutualisms that have community-wide consequences. The dynamic, and context dependent, nature of mutualisms can transform consumers, competitors, and parasites into mutualists, even while they consume, compete with, or parasitize their partner species. These dynamic, and often diffuse, mutualisms strongly affect community organization and ecosystem processes, but the historic focus on pairwise interactions decoupled from their more complex community context has obscured their importance. In aquatic systems, mutualisms commonly support ecosystem-defining foundation species, underlie energy and nutrient dynamics within and between ecosystems, and provide mechanisms by which species can rapidly adjust to ecological variance. Mutualism is as important as competition, predation, and physical disturbance in determining community structure, and its impact needs to be adequately incorporated into community theory.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.ecolsys.34.011802.132357
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  • 2
    Electronic Resource
    Electronic Resource
    Seaweed sex pheromones and their degradation products frequently suppress amphipod feeding but rarely suppress sea urchin feeding (1998)
    Springer
    Chemoecology 8 (1998), S. 91-98 
    Details
    ISSN: 1423-0445
    Keywords: Key words. algal pheromones - amphipods - Ampithoe longimana - Arbacia punctulata - brown algae - C11compounds - Dictyopteris - marine ecology - plant-herbivore interactions - sea urchins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary. A diverse group of brown seaweeds produce bouquets of C11 metabolites, some of which act as pheromones that cue gamete release or attract sperm to eggs following release. We demonstrate that these C11 metabolites and their degradation products also frequently and strongly deter feeding by the herbivorous amphipod Ampithoe longimana, but rarely by the herbivorous sea urchin Arbacia punctulata. Across the range of concentrations tested, seven of twelve C11 metabolites or mixtures that we tested deterred feeding by the amphipod, but only two of eleven deterred the sea urchin. For those compounds where we could rigorously contrast the magnitude of deterrence against the amphipod with the magnitude of deterrence against the urchin, the amphipod was deterred significantly more than the urchin by five of six metabolites. Thus, C11 compounds were more frequently and more strongly deterrent to the amphipod than to the sea urchin. These findings for C11 metabolites conflict with previous investigations, where other classes of seaweed chemical defenses have been shown to deter feeding by large mobile herbivores like urchins and fishes but to be relatively ineffective against mesograzers, especially the species of amphipod that we used here. Our results suggest that C11 metabolites are unusual among the known seaweed chemical defenses in that they are especially effective against mesograzers, which often consume seaweed spores, zygotes, and juveniles. The high concentrations of C11 metabolites in brown algal eggs could allow these defenses to be especially important in defending gametes, zygotes, or young sporelings from herbivorous mesograzers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00001809
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  • 3
    Electronic Resource
    Electronic Resource
    Seaweed secondary metabolites as antifoulants: effects of Dictyota spp. diterpenes on survivorship, settlement, and development of marine invertebrate larvae (1998)
    Springer
    Chemoecology 8 (1998), S. 125-131 
    Details
    ISSN: 1423-0445
    Keywords: Key words. antifouling – dictyol diterpenes –Dictyota– invertebrate larvae – physiological effects – secondary metabolites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary. A recent investigation showed that the brown seaweed Dictyota menstrualis was unfouled relative to co-occurring seaweeds, and that larvae of fouling invertebrates avoided settling on D. menstrualis due to chemicals on its surface. The secondary metabolites dictyol E and pachydictyol A are among the compounds found on this alga's surface. In the present study, we tested the effects of specific diterpenes from Dictyota on the survivorship, growth, and development of invertebrate larvae and developing juveniles that could foul seaweeds. Exposure to dictyol E, dictyol B acetate, pachydictyol A, and dictyodial from Dictyota menstrualis and D. ciliolata caused significant larval mortality, abnormal development, and reduce growth rates for three species of co-occurring invertebrates when their larvae were forced into contact with these metabolites. Larvae were damaged at metabolite concentrations as low as 5% of maximum possible surface concentrations of these compounds for the populations of Dictyota we studied. The negative effects of these secondary metabolites on potential foulers, in conjunction with data demonstrating larval avoidance of dictyol-covered surfaces, suggest that these compounds could function as chemical defenses against fouling, and could select for larvae that avoid hosts producing these metabolites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s000490050017
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  • 4
    Electronic Resource
    Electronic Resource
    Predictable spatial escapes from herbivory: how do these affect the evolution of herbivore resistance in tropical marine communities? (1984)
    Springer
    Oecologia 64 (1984), S. 396-407 
    Details
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Between-habitat differences in macrophyte consumption by herbivorous fishes were examined on three Caribbean and two Indian Ocean coral reefs. Transplanted sections of seagrasses were used as a bioassay to compare removal rates in reef-slope, reef-flat, sand-plain, and lagoon habitats. Herbivore susceptibility of fifty-two species of seaweeds from these habitats was also measured in the field. Seagrass consumption on shallow reef slopes was always significantly greater than on shallow reef flats, deep sand plains, or sandy lagoons. Reef-slope seaweeds were consistently resistant to herbivory while reef-flat seaweeds were consistently very susceptible to herbivory. This pattern supports the hypothesis that defenses against herbivores are costly in terms of fitness and are selected against in habitats with predictably low rates of herbivory. Sand-plain and lagoon seaweeds showed a mixed response when placed in habitats with high herbivore pressure; most fleshy red seaweeds were eaten rapidly, most fleshy green seaweeds were eaten at intermediate rates, and most calcified green seaweeds were avoided or eaten at very low rates. Differences in susceptibility between red and green seaweeds from sand-plain or lagoon habitats may result from differential competitive pressures experienced by these seaweed groups or from the differential probability of being encountered by herbivores. The susceptibility of a species to removal by herbivorous fishes was relatively consistent between reefs. Preferences of the sea urchin Diadema antillarum were also similar to those of the fish guilds. Unique secondary metabolites were characteristic of almost all of the most herbivore resistant seaweeds. However, some of the herbivore susceptible species also contain chemicals that have been proposed as defensive compounds. Genera such as Sargassum, Turbinaria, Thalassia, Halodule, and Thalassodendron, which produce polyphenolics or phenolic acids, were consumed at high to intermediate rates, suggesting that these compounds are not effective deterrents for some herbivorous fishes. Additionally, potential for the production of the compounds caulerpin, caulerpicin and caulerpenyne in various species of Caulerpa did not assure low susceptibility to herbivory. Heavily calcified seaweeds were very resistant to herbivory, but all of these species also produce toxic secondary metabolites which makes it difficult to distinguish between the effects of morphological and chemical defenses. Predictions of susceptibility to herbivory based on algal toughness and external morphology were of limited value in explaining differing resistances to herbivory.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00379139
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  • 5
    Electronic Resource
    Electronic Resource
    Competition between herbivourous fishes and urchins on Caribbean reefs (1985)
    Springer
    Oecologia 65 (1985), S. 591-598 
    Details
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary When the common sea urchin Diadema antillarum was removed from a 50 m strip of reef in St. Thomas, US Virgin Islands, cover of upright algae and the grazing rates and densities of herbivorous parrotfish and surgeonfish increased significantly within 11–16 weeks when compared to immediately adjacent control areas. Sixteen months after removal, Diadema had recovered to 70% of original density, abundance of upright algae no longer differed between removal and control areas, and the abundance and grazing activity of herbivorous fish in the removal was approaching equivalence with control areas. On a patch reef in St. Croix that had been cleared of Diadema 10–11 years earlier (Ogden et al. 1973b), urchins had recovered to only 50–60% of original density. This reef still showed significantly higher rates of grazing by fish and a significantly greater density of parrotfish and surgeonfish than a nearby control reef where Diadema densities had not been altered. These results indicate that high Diadema densities (7–12/m2 for this study) may suppress the densities of herbivorous fish on Caribbean reefs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00379678
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  • 6
    Electronic Resource
    Electronic Resource
    Associational resistance and shared doom: effects of epibiosis on herbivory (1995)
    Springer
    Oecologia 102 (1995), S. 329-340 
    Details
    ISSN: 1432-1939
    Keywords: Fouling ; Epibiosis ; Host-epibiont-herbivore interactions ; Plant-hervivore interactions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The potential for spatial associations between palatable and unpalatable plant species to reduce herbivore pressure on the palatable species has been described as associational resistance, associational refuge or associational defense for numerous terrestrial and marine communities. One of the closest associations between species-epibiosis-has not been thoroughly investigated in this regard. In this study we evaluated how different associations between host seaweeds and epibiotic plants and animals influenced the movement of an omnivorous sea urchin (Arbacia punctulata) to the host and subsequent feeding on the host. A. punctulata showed clear preferences when given pairwise choices between 12 prey species (3 animals, 9 algae). These preferences were consistent and allowed us to rank the six epibiont species and six host species linearly from least to most preferred by A. punculata. Most host-epibiont associations dramatically changed urchin preference, increasing or decreasing urchin grazing on fouled hosts as compared to clean conspecifics. Herbivory on the host increased when the epibiont was more preferred, and decreased when it was less preferred than the unfouled host alga. Taking the host species as a point of reference, we classified epibiosis-caused decrease in herbivory as associational resistance, while epibiont-caused increases in herbivory were defined as shared doom. These epibiont-host-herbivore interactions could select for hosts that facilitate the growth of certain low preference epibionts on their surfaces in situations where the resulting decreases in herbivory would offset the various negative effects of being fouled. In contrast, in situations where herbivores are common, the negative effects of being fouled by palatable epibionts may be much greater than is generally assumed. In our assays, unpalatable hosts fouled by palatable epibionts became much more attractive to urchins and rose several ranks on the urchins' preference hierarchy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00329800
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  • 7
    Electronic Resource
    Electronic Resource
    Effects of fish predation and seaweed competition on the survival and growth of corals (1998)
    Springer
    Oecologia 113 (1998), S. 231-238 
    Details
    ISSN: 1432-1939
    Keywords: Key words Coral ; Corallivory ; Florida ; Predation ; Seaweed competition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract On Caribbean coral reefs, high rates of grazing by herbivorous fishes are thought to benefit corals because fishes consume competing seaweeds. We conducted field experiments in the Florida Keys, USA, to examine the effects of grazing fishes on coral/seaweed competition. Initially, fragments of Porites divaracata from an inshore habitat were transplanted into full-cage, half-cage, and no-cage treatments on a fore-reef. Within 48 h, 56% of the unprotected corals in half-cage and no-cage treatments (62 of 111) were completely consumed. Stoplight parrotfish (Sparisoma viride) were the major coral predators, with redband parrotfish (S. aurofrenatum) also commonly attacking this coral. Next, we transplanted fragments of P. porites collected from the fore-reef habitat where our caging experiments were being conducted into the three cage treatments, half in the presence of transplanted seaweeds, and half onto initially clean substrates. The corals were allowed to grow in these conditions, with concurrent development of competing seaweeds, for 14 weeks. Although seaweed cover and biomass were both significantly greater in the full-cage treatment, coral growth did not differ significantly between cage treatments even though corals placed with pre-planted seaweeds grew significantly less than corals placed on initially clean substrate. This surprising result occurred because parrotfishes not only grazed algae from accessible treatments, but also fed directly on our coral transplants. Parrotfish feeding scars were significantly more abundant on P. porites from the half and no-cage treatments than on corals in the full cages. On this Florida reef, direct fish predation on some coral species (P. divaracata) can exclude them from fore-reef areas, as has previously been shown for certain seaweeds and sponges. For other corals that live on the fore-reef (P. porites), the benefits of fishes removing seaweeds can be counterbalanced by the detrimental effects of fishes directly consuming corals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004420050373
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  • 8
    Electronic Resource
    Electronic Resource
    Large mobile versus small sedentary herbivores and their resistance to seaweed chemical defenses (1988)
    Springer
    Oecologia 75 (1988), S. 246-252 
    Details
    ISSN: 1432-1939
    Keywords: Chemical defense ; Herbivore mobility and size ; Plant-herbivore interactions ; Seaweeds ; Terpenes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Small, relatively sedentary herbivores like amphipods and polychaetes (mesograzers) often live on the plants they consume and should therefore view plants as both foods and living sites. Large, relatively mobile herbivores like fishes commonly move among, and feed from, many plants; they should view plants primarily as foods and rarely as potential living sites. In marine communities, fishes that consume plants are also important predators on mesograzers. Since seaweeds avoided by fishes should represent safer living sites for small herbivores, mesograzers living on and consuming seaweeds that are not eaten by fishes should have higher fitness than mesograzers living on plants preferred by fishes. In previous work, we demonstrated that seaweed secondary metabolites that deterred feeding by a fish and sea urchin had no effect on feeding by a common amphipod (Hay et al. 1987a). We then hypothesized that mesograzers would, in general, be less affected by seaweed chemical defenses than larger, more mobile herbivores like fishes. In this investigation, we evaluate the generality of this hypothesis by comparing the feeding of an omnivorous fish (Lagodon rhomboides) with that of an omnivorous, tube-building polychaete (Platynereis dumerilii) to see if the mesograzer prefers seaweeds avoided by the fish and if it is less affected by seaweed chemical defense. Platynereis dumerilii fed almost exclusively on Dictyota dichotoma, the seaweed eaten least by Lagodon rhomboides. The diterpene alcohols (dictyol-E and pachydictyol-A) produced by Dictyota significantly deterred feeding by Lagodon but did not affect, or at one concentration stimulated, feeding by Platynereis. Our data support the hypothesis that small, relatively sedentary herbivores that live on plants are more resistant to chemical defenses than are large, relatively mobile herbivores that move among many plants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00378605
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  • 9
    Electronic Resource
    Electronic Resource
    A field test of inducible resistance to specialist and generalist herbivores using the water lily Nuphar luteum (1998)
    Springer
    Oecologia 116 (1998), S. 143-153 
    Details
    ISSN: 1432-1939
    Keywords: Key words Chemical ecology ; Induced defenses ; Plant-herbivore interactions ; Specialist vs. generalist herbivores ; Water lily
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We tested whether grazing by the specialist beetle Galerucella nymphaeae (Coleoptera: Chrysomelidae) induced resistance to herbivory in the water lily Nuphar luteum macrophyllum (Nymphaeaceae) using both the specialist beetle and the generalist crayfish Procambarus clarkii (Decapoda: Cambaridae). For 2 months, we allowed natural densities of beetles to develop on control plants of Nuphar, while removing beetles every 2–3 days from adjacent plants that were paired by location within our field site. By the end of the 2-month manipulation, beetle grazing had damaged twice as much leaf surface on control plants as on removal plants (30.6% vs. 14.2%, respectively). We then offered tissues from control and removal plants to adult and larval beetles and to crayfish in laboratory assays. Increased levels of previous attack by the specialist beetle either did not affect or increased water lily attractiveness to beetles, but significantly decreased attractiveness to the generalist crayfish. Beetle larvae did not feed preferentially on control vs. removal Nuphar in assays using either immature, undamaged leaves that had not yet reached the pond surface or intermediate aged leaves that had reached the surface and experienced some beetle grazing. Adult beetles consumed significantly more immature leaf tissue from the heavily grazed controls than from the less grazed removal plants but did not discriminate between control and removal leaves of intermediate age in either feeding or oviposition preference. In contrast, generalist crayfish consumed significantly more plant tissue from the less grazed treatment than from the more heavily grazed controls. Crude chemical extracts from Nuphar strongly deterred crayfish feeding, but neither phenolic content, protein content, nor differential effects of crude extracts from control vs. removal plants explained crayfish feeding on control versus removal leaves. Our assays suggest that induced resistance to crayfish may be chemically mediated, but the particular mechanisms producing this response remain unclear. Responses may be due to defensive metabolites that degrade rapidly following extraction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004420050573
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  • 10
    Electronic Resource
    Electronic Resource
    Spatial and temporal patterns in herbivory on a Caribbean fringing reef: the effects on plant distribution (1983)
    Springer
    Oecologia 58 (1983), S. 299-308 
    Details
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Blades of Thalassia testudinum Banks ex König were used in a field bioassay to assess the impact of herbivorous fishes and urchins in different habitats, at different depths, and at different times of day on a fringing reef at Galeta Point, Panama. Algal transplants were then performed to determine the effect of herbivory on algal distribution and on potential plant-plant interactions in the absence of grazers. Thalassia loss on the reef flat (0%/h) and sand plain (0%/h) was very low relative to that on the shallow reef slope (14%/h). Within the reef slope habitat, herbivore activity decreased linearly with depth. On the shallow reef slope, herbivory was highest in habitats that were most topographically complex. Herbivory was reduced in microhabitats where algal turfs had decreased structural heterogeneity by overgrowing small branching corals and filling in the cavities that these corals normally provide. On the shallow reef slope, grazing of Thalassia was lowest at night (0.3%–1%/h), rose rapidly in the morning to peak between 0900–1300 h (27%–45%/h), then dropped gradually throughout the afternoon and returned to nocturnal rates at 1900–2000 h. Herbivorous fishes did 97% of their fedding during the daytime and were responsible for more than 90% of the Thalassia removed from the reef. Urchins accounted for only 9% of the Thalassia removal, and day and night grazing rates were not markedly different. Algal species from the reef flat and sand plain are excluded from the reef slope by herbivores, not physical parameters, and should outcompete reef-slope species in the absence of herbivory. On this tropical reef, plants in the more physically benign environment appear to be selected primarily for herbivore resistance. Selection for competitive ability among seaweeds becomes increasingly important in habitats where herbivores are more exposed to their own predators or where herbivore populations are low due to periodic physical disturbances.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00385227
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