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

Abstract

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.

Fitness consequences of habitat variability, trophic position, and energy allocation across the depth distribution of a coral-reef fish

“…Across depths, tidal bores regularly deliver cold nutrient-rich water and plankton to DS reefs more frequently and for longer duration than to SS reefs (Leichter et al 2003). Although not measured directly, the availability of planktonic prey is likely higher in DS habitats compared to SS (Leichter et al 1998). Despite the expectation of higher food availability in deeper habitats, gut fullness was highest in SS reef fish and comparable between SS and MP environments.…”

“…Additionally, reefs in the Florida Keys are oceanographically connected to MP reefs at Pulley Ridge and connectivity is likely for S. partitus populations (Vaz et al 2016), suggesting that some processes that vary over geographic distances may confound the influence of depth on S. partitus populations while others such as connectivity and isolation can be excluded. Energetic trade-offs of demersal reef fishes are influenced by processes that can vary monotonically with depth such as temperature (Goldstein et al 2016a) or oceanographically driven diet and food availability (Leichter et al 1998), yet are likely mediated by patchy and less spatially predictable parameters such as predation risk. Low food consumption, lower condition, and reduced energy allocation to reproduction (Goldstein et al 2016a) in DS habitats indicate a significant role of predators and diet in shaping habitat suitability for demersal reef fish.…”

Patrones a gran escala del reclutamiento de coral en Isla Mona, Puerto Rico: evidencia de una trayectoria transitoria de comunidad después del blanqueamiento y mortalidad coralino masivo

“…Further, we propose that natural nutrient enrichment pulses can fuel up algal growth. Physical meso-scale oceanographic processes such as internal waves or seiches (Wolanski & Delesalle, 1995;Leichter, Shellenbarger, Genovese & Wing, 1998) and gyre currents (Corredor et al, 2004), in combination with local-scale micro-upwelling associated to strong tidal currents (Shea & Broenkow, 1982), may bring up deep, nutrient-rich waters towards Mona's narrow shelf. Also, groundwater infiltration might contribute natural nutrient pulses further triggering macroalgal (Lapointe, O'Connel & Garrett, 1990) and cyanobacterial blooms (Littler, Litter, Lapointe & Barile, 2006).…”

Near-surface enrichment of zooplankton over a shallow back reef: implications for coral reef food webs

“…These systems are characterized by greater water retention and entrainment . They harbor diverse guilds of hyperbenthic (Emery 1968;Carleton and Hamner 2007), demersal (Alldredge and King 1977), and endemic zooplankton as well as offshore holoplankton that have, over many generations, become resident (Roman et al 1990;Leichter et al 1998). Resident holoplankton and demersal forms would be expected to have evolved behavioral mechanisms to avoid the intense predation near the bottom.…”