413 publications from this institution
With a few notable exceptions (Borchert and Jain 1978, Inouye et at. 1980, O'Dowd and Hay 1980, Hay and Fuller 1981), most ecological studies on seed-granivore interactions in arid communities have concentrated on the adaptations and ecology of the granivores and not on characteristics of the seeds that may deter granivory. Since a large portion of the annual seed crop of many desert ephemerals is lost to seed predators (Chew and Chew 1970, French et al. 1974, Nelson and Chew 1977, Brown et al. 1979), characteristics that significantly reduce losses to granivores should be strongly selected. In this paper we show that under natural conditions seeds of the desert annual Salvia columhariae produce a glue-like substance when wetted that strongly binds sand grains to the seeds, and that seeds thus covered by sand suffer significantly less loss to desert granivores.
Coral Reef Ecology: Have We Been Putting All of Our Herbivores in One Basket? Mark E. Hay Mark E. Hay Search for other works by this author on: Oxford Academic Google Scholar BioScience, Volume 34, Issue 5, May 1984, Pages 323–324, https://doi.org/10.2307/1309391 Published: 01 May 1984
MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 307:199-208 (2006) - doi:10.3354/meps307199 Fishes learn aversions to a nudibranchs chemical defense Jeremy D. Long, Mark E. Hay* School of Biology, Georgia Institute of Technology, 310 Ferst Drive, Atlanta, Georgia 30332-0230, USA *Corresponding author. Email: mark.hay@biology.gatech.edu ABSTRACT: The nudibranch Doriopsilla pharpa was rejected as food when tethered in the field and when offered to 2 species of co-occurring crabs (the lesser blue crab Callinectes similus and the mud crab Panopeus herbstii) and 2 species of co-occurring fishes (the mummichog Fundulus heteroclitus and the striped blenny Chasmodes bosquianus) in the laboratory. When the fishes were offered squid-based artificial food containing nudibranch extracts (i.e. defended food), both species initially consumed this food, but rapidly developed aversions in subsequent feedings. Although both fishes rapidly learned to reject the food, they learned using different cues. The striped blenny Chasmodes bosquianus regurgitated following the initial feeding and then avoided all food made of squid regardless of whether or not it contained the extract. In contrast, the mummichog Fundulus heteroclitus did not regurgitate, and learned to avoid only food containing the extract; it still consumed squid-based food without the extract. Thus, the mummichog detected the deterrent chemical and avoided only defended food while the striped blenny was a less effective feeder, avoiding both defended and undefended food that tasted like squid. Bioassay-guided separation using the mummichog demonstrated that the sesquiterpene polygodial was responsible for the deterrent effects of the nudibranch extract. This metabolite also resulted in the striped blenny avoiding either squid- or tuna-based food treated with this metabolite. KEY WORDS: Fish behavior · Predatorprey interactions · Chemical ecology · Oyster reef Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 307. Online publication date: January 24, 2006 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2006 Inter-Research.
Dr. Mark Hay of the Georgia Tech School of Biology will discuss the ecology of coral reefs and their connection to pharmaceuticals from the sea
Abstract Loss of larger consumers from stressed ecosystems can lead to trophic release of mid‐level consumers that then impact foundation species, suppressing ecosystem function and resilience. For example, in coral reef ecosystems, outbreaks of coral predators like crown‐of‐thorns sea stars have been associated with fishing pressure and can dramatically impact the composition and persistence of corals. However, the ecological impacts, and consequences for management, of smaller, less obvious corallivores remain inadequately understood. We investigated whether reef state (coral vs. seaweed domination) influenced densities and size frequencies of the corallivorous gastropod Coralliophila violacea on its common host, the coral Porites cylindrica, within three pairs of small Marine Protected Areas ( MPA s) and adjacent fished areas in Fiji. C. violacea densities were 5–35 times greater, and their size frequencies more broadly distributed, within seaweed‐dominated fished areas than in adjacent MPA s dominated by corals. Tethering snails (4–9 mm in shell height) in place on their coral hosts indicated that suppression of snails in MPA s was due to predation, apparently by fishes. When tethered on the benthos (where they rarely occur), rather than on their host, mortality of larger snails (15.0–25.0 mm in shell height) was high in all areas, primarily due to hermit crabs killing them and occupying their shells. Because C. violacea is a sessile gastropod that feeds affixed to the base of corals and produces minimal visible damage, it has been considered a “prudent feeder” that minimally impacts its host coral. We assessed this over a 24‐d feeding period in the field. Feeding by individual C . violacea reduced P . cylindrica growth by ~18–43% depending on snail size. Our findings highlight the considerable, but underappreciated, negative impacts of this common corallivore on degraded reefs. As reefs degrade and corals are lost, remaining corals (often species of Porites ) may gain the full attention of elevated densities of coral consumers. This will further damage the remaining foundation species, suppressing the resilience of corals and enhancing the resilience of degraded, seaweed‐dominated reefs.
Several dominant, shallow-water seaweeds from the Caribbean are physiologically capable of transiting the freshwater of the Panama Canal, surviving both the marked salinity changes and the required time spent in freshwater. Some of these species are known to settle and grow on boat bottoms, thus providing a direct method for transport through the canal. However, they are rare or absent on the Pacific coast. The primary barrier to the successful transport and establishment of these species appears to be herbivore activity and the lack of reef-generated refuge areas on the Pacific coast, not the salinity of the Panama Canal. IN THE 70 YEARS THAT THE PANAMA CANAL HAS LINKED THE WESTERN CARIBBEAN AND THE EASTERN PACIFIC, very few interoceanic colonizations have been documented. It is generally assumed that the major barrier to transfer of marine species between oceans has been the freshwater in the canal. Thus, the discussions of potential colonizations have focused primarily on transfers that might occur if a new, sea-level canal were constructed or on species that might be carried in the ballast tanks of ships (Briggs 1968, 1969; Rubinoff 1968; Topp 1969; Springer 1973; Glynn 1982; but see Menzies 1968). Here we focus on direct transfer of adult seaweeds, many of which are shown to be tolerant of long exposure to freshwater. Disjunctions in herbivore impact often determine the local distribution of plant populations or community types in marine environments (Kitching and Ebling 1961; Randall 1965; Jones and Kain 1967; Ogden et al. 1973; Lubchenco and Menge 1978; Lubchenco 1980; Hay 198 la, b, c; Underwood and Jernakoff 1981; Hay et al. 1983). Herbivory also appears to be a primary factor maintaining the between-habitat diversity of seaweeds on coral reefs (Hay 1981a, Hay et al. 1983) and has been hypothesized to be important in maintaining distributional boundaries on a geographic scale (Lubchenco 1980, Hay 1981a, Lubchenco and Gaines 1981, Gaines and
This article is a commentary on Smilanich et al ., 210 : 1044–1057 .
South Africa s past has to be grappled with, courageously and penetratingly. Especially its recent decades of human rights violations inflicted by the injustice of apartheid, have to be confronted frankly and constructively. In the light of what other countries have done, South Africa opted for a Commission that would do its utmost to uncover the truth and to contribute towards reconciliation. Using as a frame of reference the demanding objectives that had been set for this Commission, this article presents a brief discussion of the functioning of the Commission and an initial assessment of its achievements. The overwhelming and almost impossible task, further complicated by practical and psychological limitations, is taken into consideration. What has nevertheless been accomplished, is duly recognised and appraised. Preliminary conclusions are given for the ongoing responsibilities of respect, reparation and reconciliation. These do not only apply to South Africa s road ahead, but also to all situations where truth has to be revealed and people have to be reconciled.
Many seaweeds and terrestrial plants induce chemical defences in response to herbivory, but whether they induce chemical defences against competitors (allelopathy) remains poorly understood. We evaluated whether two tropical seaweeds induce allelopathy in response to competition with a reef-building coral. We also assessed the effects of competition on seaweed growth and seaweed chemical defence against herbivores. Following 8 days of competition with the coral Porites cylindrica , the chemically rich seaweed Galaxaura filamentosa induced increased allelochemicals and became nearly twice as damaging to the coral. However, it also experienced significantly reduced growth and increased palatability to herbivores (because of reduced chemical defences). Under the same conditions, the seaweed Sargassum polycystum did not induce allelopathy and did not experience a change in growth or palatability. This is the first demonstration of induced allelopathy in a seaweed, or of competitors reducing seaweed chemical defences against herbivores. Our results suggest that the chemical ecology of coral–seaweed–herbivore interactions can be complex and nuanced, highlighting the need to incorporate greater ecological complexity into the study of chemical defence.
