Breaking internal waves on a Florida (USA) coral reef: a plankton pump at work?

Temperature, salinity, flow speeds, and pldnklvn concentrations can be highly variable on the slope of Conch Reef, Florida Keys (USA), as warm surface water is mixed with cool, subsurface water forced onshore by broken internal waves. In August 1995 the water column seaward of the reef exhibited strong temperature and density stratification with a sharp pycnocline and associated subsurface chlorophyll a maximum layer at 45 to 60 m depth. On the reef slope, near-bottom zooplankton sampling at 22 to 28 m showed high concentrations of calanoid copepods, crab zoea, and fish larvae associated with upslope flow of cool, chlorophyll-rich water. In contrast to these periods of high concentrations, zooplankton concentrations were low during periods of long-shore and offshore flow of warm surface waters. Both the frequency of internal bore arrival and the mean durat~on of cool water events increase with increasing depth on the reef slope. Delivery of zooplankton to the reef is, thereforit, d s o erpec:ed :G incic;sc '.:i?h dcpth. 2 sh?r!-term se!!!emen! experiment showed increased settlement of serpulid worms at 20 and 30 m depth compared with 15 m, and a 15.5 mo transplant experiment showed significantly enhanced growth rates of the suspens~on-feeding coral Madracis mirabilis (Scleractinia: Pocilloporidae) at 30 m depth relative to growth at 15 or 20 m. Internal tidal bores appear to be a predictable, periodic source of cross-shelf transport to Florida coral reefs and an important influence on the spatial and temporal heterogeneity of suspended food particles and larval delivery to the benthos.

[1]  D. R. Robertson,et al.  Temporal Coupling of Production and Recruitment of Larvae of a Caribbean Reef Fish , 1988 .

[2]  N. F. Smyth,et al.  Hydraulic Jump and Undular Bore Formation on a Shelf Break , 1988 .

[3]  M. Bertness,et al.  Dispersal of juveniles and variable recruitment in sessile marine species , 1992, Nature.

[4]  Bertness,et al.  Wind-driven settlement patterns in the acorn barnacle Semibalanus balanoides , 1996 .

[5]  J. Roughgarden,et al.  Spatial population-dynamics of a marine organism with a complex life-cycle , 1990 .

[6]  L. Atkinson,et al.  Observations of a Gulf Stream frontal eddy on the Georgia continental shelf, April 1977 , 1981 .

[7]  L. Cooper,et al.  Internal Waves and Upwelling of Oceanic Water from Mid-depths on to a Continental Shelf , 1947, Nature.

[8]  Eric Wolanski,et al.  Upwelling by internal tides and Kelvin waves at the continental shelf break on the Great Barrier Reef , 1983 .

[9]  K. Sebens,et al.  Zooplankton capture by two scleractinian corals,Madracis mirabilis andMontastrea cavernosa, in a field enclosure , 1996 .

[10]  L. Atkinson.  Modes of Gulf Stream intrusion into the South Atlantic Bight Shelf Waters , 1977 .

[11]  Wing,et al.  Spatial structure of relaxation events and crab settlement in the northern California upwelling system , 1995 .

[12]  A. Shanks.  Mechanisms of Cross-Shelf Dispersal of Larval Invertebrates and Fish , 2020 .

[13]  Jessica Pineda.  Predictable Upwelling and the Shoreward Transport of Planktonic Larvae by Internal Tidal Bores , 1991, Science.

[14]  L. Atkinson,et al.  Low‐frequency current and temperature variability from Gulf Stream frontal eddies and atmospheric forcing along the southeast U.S. outer continental shelf , 1983 .

[15]  S. Morgan.  Plasticity in reproductive timing by crabs in adjacent tidal regimes , 1996 .

[16]  M. Clarke,et al.  Influence of Florida Current, gyres and wind-driven circulation on transport of larvae and recruitment in the Florida Keys coral reefs , 1992 .

[17]  C. Epifanio.  Transport of blue crab (Callinectes sapidus) larvae in the waters off mid-Atlantic states , 1995 .

[18]  Brian Helmuth,et al.  Effects of water flow and branch spacing on particle capture by the reef coral Madracis mirabilis (Duchassaing and Michelotti) , 1997 .

[19]  P. Sale.  Distribution of Larval Acanthuridae off Hawaii , 1970 .

[20]  J. Porter.  Autotrophy, Heterotrophy, and Resource Partitioning in Caribbean Reef-Building Corals , 1976, The American Naturalist.

[21]  J. Roughgarden,et al.  Cross-shelf transport causes recruitment to intertidal populations in central California , 1991 .

[22]  W. Hamner,et al.  Topographically Controlled Fronts in the Ocean and Their Biological Influence , 1988, Science.

[23]  P. Dustan,et al.  Growth and form in the reef-building coral Montastrea annularis , 1975 .

[24]  G. Thorson.  REPRODUCTIVE and LARVAL ECOLOGY OF MARINE BOTTOM INVERTEBRATES , 1950, Biological reviews of the Cambridge Philosophical Society.

[25]  A. Hastings,et al.  The influence of spatially and temporally varying oceanographic conditions on meroplanktonic metapopulations , 1994 .

[26]  J. Roughgarden,et al.  Supply side ecology: the role of physical transport processes , 1987 .

[27]  J. Pineda.  An internal tidal bore regime at nearshore stations along western U.S.A.: Predictable upwelling within the lunar cycle , 1995 .

[28]  M. Kingsford,et al.  Influence of surface slicks on the distribution and onshore movements of small fish , 1986 .

[29]  E. Wolanski,et al.  Influence of tidally induced fronts and Langmuir circulations on distribution and movements of presettlement fishes around a coral reef , 1991 .

[30]  C. Roberts,et al.  Connectivity and management of caribbean coral reefs , 1997, Science.

[31]  Mark W. Denny,et al.  Pulsed delivery of subthermocline water to Conch Reef (Florida Keys) by internal tidal bores , 1996 .

[32]  A. Shanks.  TIDAL PERIODICITY IN THE DAILY SETTLEMENT OF INTERTIDAL BARNACLE LARVAE AND AN HYPOTHESIZED MECHANISM FOR THE CROSS-SHELF TRANSPORT OF CYPRIDS , 1986 .

[33]  R. Cowen,et al.  Relation of coral reef fish larval distributions to island scale circulation around Barbados, West Indies , 1994 .

[34]  M. Clarke,et al.  Evolution of the Tortugas Gyre and its influence on recruitment in the Florida Keys , 1994 .

[35]  A. Shanks.  Surface slicks associated with tidally forced internal waves may transport pelagic larvae of benthic invertebrates and fishes shoreward , 1983 .

[36]  J. Cairns.  Asymmetry of internal tidal waves in shallow coastal waters , 1967 .

[37]  L. Atkinson,et al.  Climatology of the Southeastern United States Continental Shelf Waters , 1983 .

[38]  D. A. Brooks,et al.  Pulsed phytoplankton supply to the rocky subtidal zone: influence of internal waves. , 1993, Proceedings of the National Academy of Sciences of the United States of America.

[39]  C. Young.  Larval ecology of marine invertebrates: A sesquicentennial history , 1990 .

[40]  H. Sandstrom,et al.  Internal tide and solitons on the Scotian Shelf: A nutrient pump at work , 1984 .

[41]  J. Roughgarden,et al.  Larval settlement rate: A leading determinant of structure in an ecological community of the marine intertidal zone. , 1985, Proceedings of the National Academy of Sciences of the United States of America.

[42]  J. Pineda.  Internal tidal bores in the nearshore: warm-water fronts, seaward gravity currents and the onshore transport of neustonic larvae , 1994 .