GENIN, AMATZIA, Ph.D.
Born: 1951, Kfar Saba (Israel);
Ph.D. 1987, Scripps Institution of Oceanography, University of California San Diego,
California, USA.
Lecturer, Department of Evolution, Systematics and Ecology, The Hebrew University: 1987.
Senior Lecturer: Department of Evolution, Systematics and Ecology, The Hebrew University: 1994
Research Interests:
Biological oceanography and coral-reef ecology. Benthic-pelagic coupling. Predator-prey
interactions in the marine environment. Biomechanics and effects of flow on corals,
invertebrates and fish.
Research Projects:
1. Predation on zooplankton and phytoplankton and removal of Dissolved Organic Matter
(DOM) by coral-reef fish and benthic suspension feeders.
Funding: US-Israel Binational Science Foundation
2. Ocean flow and zooplankton dynamics in coastal waters using advanced acoustic techniques.
Funding: The German Ministry of Science & Technology.
3. Characterization, formation and breakdown of small-scale patterns in zooplankton
distribution.
Funding: The Israel Science Foundation.
4. Swimming behavior of individual zooplankton during night-time foraging.
Funding: US Office of Naval Research.
5. Long-term monitoring of environmental parameters in the Northern Gulf of Eilat.
Keywords: zooplankton, coral reef, water flow, predator-prey interaction, competition,
community structure, biomechanics, fish, long-term monitoring.
Selected Abstracts:
1.
Zooplankton patch dynamics: effects of currents, topography, and predation by fish.
In the ocean, as on land, the distributions of most organisms are characterized by
spatial heterogeneity, or patchiness. The understanding of processes responsible
for the formation and dynamics of zooplankton patchiness is a major scientific
goal in biological oceanography. The mechanisms responsible for patchy distributions,
particularly for the considerable patchiness exhibiting no correspondence to
variations of physical properties, have been the subject of much speculation but
remain poorly understood. In our research we have demonstrated, for the first time,
an occurrence of highly-predictable, daily formation of zooplankton patches (gaps),
both in the open ocean and in coastal habitats. In the open ocean, gaps are formed
in the evening above the summits of shallow seamounts and banks due to interactions
between the migrating animals, their predators, physical advection, and the local
topography. At the coastal habitats, a remarkable (factor of 4 to 5) reduction in
zooplankton abundance occurs near the reef, compared with the open waters, and that
the water passing through coral-reef fish community is gradually being depleted of
zooplankton in a rate of approximately 40% per hour. A zooplankton gap is thereby
formed near the reef. On even a smaller scale, we are currently studying gap formation
around individual predators (fish).
2.
Benthic ecology and flow: effects of water physics on competitive superiority and
tissue recovery in stony corals.
Competition for space is considered to be a major process structuring coral-reef
communities. A common competitive strategy of corals is the use of aggressive
attacks against neighboring colonies, resulting in permanent damage of the
subordinate coral. Our work show that water flow can greatly affect the competitive
superiority among competing corals. Specifically, aggression of corals at
current-swept reefs is far less effective than at protected sites. In a set of
experiments we discovered that enhances zooplankton predation by the corals,
which, in turn, fosters the recovery of coral tissues damaged by an aggressive
neighbor or by other means.
3.
Long-term monitoring in the northern Gulf of Eilat: rare events in the coral
reef driven by climatic variability.
The ecological literature, particularly during the last decade, has clearly
demonstrated the importance of long-term studies (order of 10-100 yrs). No
habitat can be adequately characterized without thorough information on
long-term variability in environmental parameters. We have therefore initiated
a long-term monitoring program, comprising continuous (or daily) measurements
of key environmental parameters (temperature, chlorophyll, sea-level, currents)
in the waters off our laboratory. The data collected so far were instrumental for
understanding a major climatically-driven disturbance that occurred in early
spring 1992 in the coral reefs (published in Nature in 1995, see below).
The unusually cold winter of 1991-92 led to an extremely deep mixing of the
water column, resulting in two- to three-fold increase in nutrient and chlorophyll
concentrations. By spring, a thick algal mat covered extensive sections of the
coral reef, smothering some 20% of the corals. The implications of our
observations are relevant for both general coral-reef ecology and for the
management of anthropogenic effects in such ecosystems.
4.
Foraging in planktivorous fish: bio-mechanical limitations and adaptations for
feeding in moving fluids.
Zooplankton feeding by fish is a major link between benthic and pelagic realms
in coral reefs, kelp beds and other coastal marine habitats. In many cases the
majority of the fish are small, site-attached species which forage on zooplankton
drifted into their home range with the flowing waters. Although the contribution
of those fish to carbon and nutrient fluxes across habitats can be significant,
very little is known about the mechanisms involved in this mode of predation.
Recent and preliminary findings at our laboratory indicate that the functional
response of the fish linearly increases with increasing prey density, with higher
predation rates on aggregated, compared with dispersed, prey. Strong flow, on the
other hand, restricts the size of the volume in which the fish capture prey,
leading to a poor functional response when the increase in prey flux is due to
increasing flow speeds. Our current focuses on four, potentially key, aspects of
zooplanktivory by the diverse guild of site-attached coral-reef fishes: the
foraging on patchy prey, the bio-mechanical constraints imposed by the flow on
the fishes' foraging motions, niche separation based on levels of exposure to
flow, and competition between fish within a group. The study is carried out both
in situ and in a set of large laboratory flumes, using advance acoustic and
optical technology.
Recent Publications:
- Genin, A., L. Karp and A. Miroz. 1994. Effects of flow on competitive superiority
in scleractinian corals. Limnology and Oceanography 39:913-924.
- Genin, A., C. Greene, L. Haury, P. Wiebe, G. Gal, S. Kaartvedt, E. Meir, C. Fey and
J. Dawson (1994) Zooplankton patch dynamics: daily gap formation over abrupt topography.
Deep-Sea Research 41:941-951.
- Trager, G., Y. Achituv and A. Genin (1994) Effects of prey escape ability, flow speed,
and predator feeding mode on zooplankton capture by barnacles. Marine Biology 120:251-259.
- Liberman, T., A. Genin and Y. Loya (1995) Effects on growth and reproduction of the
coral Stylophora pistillata by the mutualistic damselfish Dascyllus marginatus.
Marine Biology 121:741-746.
- Haury, L., C. Fey, G. Gal and A. Genin (1995) Copepod carcasses in the ocean.
I. Over seamounts. Marine Ecology Progress Series 123:57-63.
- Genin, A., G. Gal and L. Haury (1995) Copepod carcasses in the ocean.
II. Near coral reefs. Marine Ecology Progress Series 123:65-71.
- Fabricius, K. E., A. Genin and Y. Benayahu (1995) Flow-dependent herbivory
and growth in zooxanthellae-free soft corals. Limnology and Oceanography 40:1290-1301.
- Fabricius, K. E., Y. Benayahu and A. Genin (1995) Herbivory in asymbiotic soft corals.
Science 268:90-92.
-Genin, A., B. Lazar and S. Brenner (1995) Atmospheric cooling, unusual vertical
mixing and coral mortality following the eruption of Mt. Pinatubo. Nature 377:507-510.
- Kiflaw, M. and A, Genin (1997) Prey flux manipulation and the feeding rates of
reef dwelling planktivorous fish. Ecology 78:1062-1077.
- Vago, R., M. Ben-Zion, Z. Dubinsky, A. Genin and Z. Kizner (1998) Growth rates
of three symbiotic corals in the Red Sea. Limnology & Oceanography 42:1814-1819.
- Genin A. and K. Sebens (Editors) Flow and coral reefs: from micro- to meso-scale effects.
The 8th International Coral-Reef Symposium, Panama, 1996.
- Fabricius, K., G. Yahel and A. Genin (1998) In situ depletion of phytoplankton by an
azooxanthellate soft coral. Limnology & Oceanography 43:354-356.
- Yahel, G. , A. Post, K. Fabricius, D. Marie and D. Vaulot. (1998) Phytoplankton
distribution and grazing near coral reefs. Limnology & Oceanography 43:551-563.
- Genin, A. and N. Paldor (1998). Changes in the circulation and current spectrum near
the tip of the narrow, seasonally mixed, Gulf of Elat. Israel Journal of Earth Sciences,
47, 87-92.
Contact address:
Interuniversity Institute for Marine Sciences,
P.O. Box 469,
Eilat 88103,
Israel
Tel: 972-7-6360124
Fax: 972-7-6374329
or
Department of Evolution, Systematic and ecology, The Hebrew University of Jerusalem,
Email: amatzia@vms.huji.ac.il
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