Diel movements of fishes linked to benthic seascape structure in a Caribbean coral reef ecosystem

Abstract

Many common fishes associated with Caribbean coral reef ecosystems use resources from more than 1 patch type during routine daily foraging activities. Few studies have provided direct evidence of connectivity across seascapes, and the importance of benthic seascape structure on movement behavior is poorly known. To address this knowledge gap, we coupled hydro-acoustic technology to track fish with seafloor mapping and pattern analysis techniques from landscape ecology to quantify seascape structure. Bluestriped grunts Haemulon sciurus and schoolmaster snapper Lutjanus apodus were tracked over 24 h periods using boat-based acoustic telemetry. Movement pathways, and day and night activity spaces were mapped using geographical information system (GIS) tools, and seafloor structure within activity spaces was mapped from high-resolution aerial photography and quantified using spatial pattern metrics. For both fish species, night activity spaces were significantly larger than day activity spaces. Fish exhibited a daytime preference for seascapes with aggregate coral reef and colonized bedrock, then shifted to night activity spaces with lowercomplexity soft sediment including sand, seagrass, and scattered coral/rock. Movement path complexity was negatively correlated with seascape complexity. This demonstrates direct connectivity across multiple patch types and represents the first study to apply quantitative landscape ecology techniques to examine the movement ecology of marine fish. The spatially explicit approach facilitates understanding to the linkages between biological processes and the heterogeneity of the landscape. Such studies are essential for identifying ecologically relevant spatial scales, delineating essential fish habitat and designing marine protected areas.

Assessing fine-scale diel movement patterns of an exploited coral reef fish

“…Instead, crepuscular and night hKUDs were spread across the monitored area, encompassing reef crest, slope and sandy regions. Patrolling large areas across habitat types could provide greater foraging opportunity among patches of sand between areas of coral cover in depths of greater than 7 m. Analysis of paths of movement and tortuosity (e.g., [14]) would assist in elucidating evidence of feeding activity. Interestingly, individuals displayed relatively consistent depth use within the water column between reef crest and outer sand habitat, particularly for individuals with the most data (i.e.…”

“…With most fishes being either diurnal or nocturnal, a complex sequence of events occurs on coral reefs during dusk and dawn transition periods [3]. Patterns in daily activity influence how species persist in their environment and adapt to different niches [14]. For nocturnal species, foraging typically occurs during crepuscular and night periods while daylight hours are spent resting or patrolling [3,15].…”

Characterizing trophic ecology of generalist consumers: a case study of the invasive lionfish in The Bahamas

“…Schoolmaster snapper individuals forage over a scale of tens to hundreds of meters over a span of hours in these Bahamian ecosystems (Hammerschlag-Peyer & Layman 2010), thus allowing for prey selection across multiple habitat types (Hitt et al 2011). Foraging at this scale would allow individuals to sample from a larger potential prey pool, not just the organisms that inhabit a resident patch.…”

Habitat connectivity and spatial complexity differentially affect mangrove and salt marsh fish assemblages

“…As a result, each focal patch will have a combination of connectivity and structural complexity variables that could result in a distinct species assemblage (Faunce & Serafy 2008). Research has highlighted both the importance of well-connected (Tanner 2006, GroberDunsmore et al 2008, Boström et al 2011, Hitt et al 2011) and structurally complex focal patches (Gratwicke & Speight 2005, Verweij et al 2006, Boström et al 2011 for supplementing species richness and population density (Pittman et al 2007). …”

“…3). Complex seascapes may also result in direct connectivity, reducing fish movement paths between patches (Hitt et al 2011).…”