groupers and their associated reef fish assemblage near cape fear, north carolina, were observed using scuba and underwater stationary videography during a 7-mo period. fifty-seven sites were visited with stationary video and diver point counts of groupers were taken at each site. primary observations by both techniques were made on gag, Mycteroperca microlepis (goode and bean, 1879), and scamp, Mycteroperca phenax Jordan and swain, 1884, while other grouper species were noted for videos only. comparisons of gag and scamp density were made using baited and unbaited stationary camera deployments on high-and low-relief ledge habitats. inferred minimum population sizes by location ranged from 0 to 4 gag, 0 to 13 scamp, and 0 to 2 yellowmouth, Mycteroperca interstitialis (poey, 1860), using stationary video. estimated densities by video camera were highest for scamp at 480 ha −1. gag density was estimated at 145 ha-1 and yellowmouth grouper at 50 ha −1. in total, 68 fish species including groupers were recorded by video and richness by site ranged from 10 to 26 (n = 34; mean 18.9, sd 4.2). reef fish community structure as measured by mean bray-curtis dissimilarity between paired sites was 0.339 (0.219 sd) indicating a substantial overlap in species composition between most sites. given the economic importance of the snapper-grouper complex and the desire to develop non-extractive (or reduced impact) survey techniques, stationary video observations hold promise for monitoring changes in reef fish assemblages.

The invasion of Indo-Pacific lionfish (Pterois volitans/P. miles) throughout the Caribbean and southeastern U.S. Atlantic represents a significant ecological threat, yet few studies have examined the daily activity and movement patterns of this invasive species. In this study, passive acoustic telemetry was used to track lionfish at 4 coral reef sites in the Florida Keys. Fourteen lionfish were tagged among the 4 sites, and the total number of days tagged fish were detected ranged from 5 to 141 days. Hourly detection data revealed diel activity patterns with peaks at dawn and dusk. Mixed model analysis of detection data indicated a significant effect of time of day, with lionfish activity greater at twilight than during day or night. These results support observations from previous studies that lionfish are most active at dawn and dusk when they are foraging. The 95% kernel utilization distribution home range size ranged from 360-18,812 m 2. Lionfish movements were generally localized, with mean daily distance moved ranging from 24-116 m, although one lionfish had a maximum daily distance moved of 427 m. Short-term activity centers revealed possible diel shifts in micro-habitat use for 2 lionfish, as well as an emigration of one lionfish to an adjacent patch reef ~2 00 m away. These findings increase our understanding of lionfish behavior on coral reefs and highlight the need for more detailed studies examining fine-scale habitat use and movements across more habitat types. The results from this study will further contribute to the spatial information required to improve the effectiveness of monitoring and controlling lionfish populations in the Florida Keys.

Observing multiple size classes of organisms, along with oceanographic properties and water mass origins, can improve our understanding of the drivers of aggregations, yet acquiring these measurements remains a fundamental challenge in biological oceanography. By deploying multiple biological sampling systems, from conventional bottle and net sampling to in situ imaging and acoustics, we describe the spatial patterns of different size classes of marine organisms (several microns to ∼10 cm) in relation to local and regional (m to km) physical oceanographic conditions on the Delaware continental shelf. The imaging and acoustic systems deployed included (in ascending order of target organism size) an imaging flow cytometer (CytoSense), a digital holographic imaging system (HOLOCAM), an In Situ Ichthyoplankton Imaging System (ISIIS, 2 cameras with different pixel resolutions), and multi-frequency acoustics (SIMRAD, 18 and 38 kHz). Spatial patterns generated by the different systems showed size-dependent aggregations and differing connections to horizontal and vertical salinity and temperature gradients that would not have been detected with traditional station-based sampling (∼9-km resolution). A direct comparison of the two ISIIS cameras showed composition and spatial patchiness changes that depended on the organism size, morphology, and camera pixel resolution. Large zooplankton near the surface, primarily composed of appendicularians and gelatinous organisms, tended to be more abundant offshore near the shelf break. This region was also associated with high phytoplankton biomass and higher overall organism abundances in the ISIIS, acoustics, and targeted net sampling. In contrast, the inshore region was dominated by hard-bodied zooplankton and had relatively low acoustic backscatter. The nets showed a community dominated by copepods, but they also showed high relative abundances of soft-bodied organisms in the offshore region where these organisms were quantified by the ISIIS. The HOLOCAM detected dense patches of ciliates that were too small to be captured in the nets or ISIIS imagery. This near-simultaneous deployment of different systems enables the description of the spatial patterns of different organism size classes, their spatial relation to potential prey and predators, and their association with specific oceanographic conditions. These datasets can also be used to evaluate the efficacy of sampling techniques, ultimately aiding in the design of efficient, hypothesis-driven sampling programs that incorporate these complementary technologies.

The formation of fish spawning aggregations (FSAs) is an essential part of the life history of many economically important fish species; however, their status are often poorly described in the literature either due to their occurrence in remote locations, during seasons with unsafe ocean conditions, or because they move on space and time scales that are difficult to predict and validate. Even in areas that are relatively accessible and heavily fished, such as southeast Florida, regionally relevant information describing FSA dynamics is generally absent from the literature and unaccounted for in existing management plans. We propose that this can be attributed to the fact that information is often held by stakeholders or found in unpublished manuscripts and reports. These sources are not widely disseminated and are therefore difficult to locate and integrate into fisheries management decisions. In this paper, we present a case study demonstrating the value of regional data syntheses as a tool to improve management activities in southeast Florida. Specifically, we engaged with local stakeholders to collect reports of FSA occurrence, and used Web of Science queries to collate information describing the reproductive dynamics of locally occurring snapper and grouper species. Reports were combined with regional FSA literature and provided to managers as a support tool to anticipate FSA occurrence, and to guide policy development and future FSA research. Resource users identified 13 potential aggregations from five species, but Web of Science queries revealed a paucity of information. Echosounder, camera, and fisheries dependent surveys were then used to corroborate reportedly active cubera snapper (Lutjanus cyanopterus), hogfish (Lachnolaimus maximus), and gag grouper (Mycteroperca microlepis) aggregations. Variability in the spatiotemporal aspects of FSA occurrence make them difficult to study, but this may also explain how certain species have avoided detrimental impacts from aggregation fishing. These data represent a first step toward describing FSAs that have historically occurred in the Southeast Florida Coral Reef Ecosystem Conservation Area and can be used by managers to prioritize future research efforts focused on species or hotspots of multispecies activity along the northern extent of the Florida Reef Tract.

Coastal fish communities are under increasing levels of stress associated with climate variation and anthropogenic activities. However, the high degree of behavioral plasticity of many species within these communities allow them to cope with altered environmental conditions to some extent. Here, we combine meteorological information, data from hydroacoustic surveys, and recordings of goliath grouper sound production to examine the response of coastal fish communities to heavy rainfall events in South Florida, USA, that resulted in the release of excess storm water into surrounding estuaries and coastal waters. We observed a nearly 12,000% increase in water column acoustic backscatter following a heavy rainfall event of September 16th, 2015. Interestingly, estimates of school backscatter, a proxy for biomass, increased by 172% with the onset of the perturbation. Schooling fish density also increased by 182%, as did acoustically derived estimates of mean schooling fish length (21%). Following the perturbed period, school backscatter decreased by 406%, along with schooling density (272%), and mean schooling fish length (35%). Hydrophone and hydroacoustic data also revealed that goliath grouper (Epinephelus itajara) spawning aggregations were persistent in the region throughout the duration of the study and continued to exhibit courtship behavior during the perturbed period. Our observations demonstrate the high level of resistance common in coastal species but raises new questions regarding the threshold at which fish communities and reproductive activities are disrupted. As coastal land use continues to increase, and the effects of global climate change become more pronounced, more Before-After Control Impact (BACI) studies will provide improved insight into the overall response of nearshore communities to future perturbations and the cumulative effect of repeated perturbations over extended periods.