larger fish have greater thermal inertia and increased cardiac capacity
Thermal inertia is the ability of a body or object to maintain its temperature when ambient temperature changes. Larger objects have higher thermal inertia, so larger fish lose heat more slowly than smaller fish. Larger fish also have larger hearts, which can pump more blood. AWC
niche
conditions under which an animal lives -RKL
ILD
Isothermal Layer Depth YS & WT
SST
Sea Surface Temperature YS & WT
quantified
measured
sinuous
Definition- Having many curves and turns. D.N.B.
garnered
collected
spatiotemporal information
Information relative to the space and time of the tagged fish. --MSars
peritoneally implanted archival tags
attaching archival tags inside the stomach lining,
Energy intake and thermal excess were positively correlated with body size as measured by the curved fork length (CFL) of tagged tunas
A big tuna (large body size) requires more energy which means it needs to feed from a higher amounts of prey or big preys. Consequently, the heat production is higher provoking a thermal excess. YS & WT
The largest size-based differences in energy intake were also observed in October (Fig. 6 and table S3), indicating that thermal niche expansion in this endothermic species results in high energetic reward
The increased temperature range allowed the tuna to forage and obtain energy more efficiently. -SES
heterogeneity
The quality or state of being diverse in character or content RS
peritoneal
Peritoneal- The area that contains the abdominal organs. The sentence references the peritoneal temperature, so that is the temperature in the abdominal region.
viscerally
Internal organs within the main cavities of the body RS
bradycardia
The decrease of heart rate while the fish dive to deep waters. WT & YS
our findings suggest that the overexploitation of spawning aggregations can fundamentally alter the natural predator-prey equilibrium, limiting foraging options for reef sharks within aggregation sites.
The inverted biomass pyramid is a good thing, but the fish spawning aggregations play an important role in whether or not this stays a good thing.
We evaluated shark residency in the pass using acoustic telemetry
This was used to determine if the sharks were regularly leaving the pass to forage.
Bioenergetics models
Bioenergetics is a field in biochemistry and cell biology that concerns energy flow through living systems. This bioenergetics model is showing how much energy sharks require.
McCauley, D.J., Young, H.S., Dunbar, R.B., Estes, J.A., Semmens, B.X., and Micheli, F. (2012). Assessing the effects of large mobile predators on ecosystem connectivity. Ecol. Appl. 22, 1711–1717.
This study states that sharks in the Palmyra Atoll find food in other habitats.
-RKL
enabling us to determine whether sharks are feeding, rather than only resting
allowing us to find out whether sharks are feeding or are just resting.
Trebilco et al. present two mechanisms by which low energy availability is typically escaped: the largest predators (1) feed at sufficiently expansive spatial scales to “skim the tops of multiple spatially discrete local biomass pyramids” (i.e., foraging outside the pass, which we rarely observed) or (2) forage extensively at the bottom of “widely dispersed and seasonally variable pyramids,” which applies to whale sharks, but not reef sharks [9].
Trebilco discussed two different methods the sharks can use to have enough food for survival.
-KA & MC
These observations confirmed that hundreds of sharks actively feed on a large variety of prey (at least 14 fish species; Figures 4 and S3). In particular, sharks feed aggressively on the large number of groupers present during spawning aggregations in June and July [13]. Shark abundance and residency times both increase when camouflage groupers (Epinephelus polyphekadion) arrive from the surrounding reef area to spawn
there is an active correlation between the populations of prey and predators, when the camouflage groupers aggregate in order to spawn. This increase in prey is what attracts the sharks. MSARS , WT & YS
Contrary to previous findings
Previous work said that the sharks were traveling to different habitats to find food.
McCauley, D.J., Young, H.S., Dunbar, R.B., Estes, J.A., Semmens, B.X., and Micheli, F. (2012). Assessing the effects of large mobile predators on ecosystem connectivity. Ecol. Appl. 22, 1711–1717.
-RKL
residency times
This is the length of an animal spends exclusively in one area. -AWC
UVCs
Underwater Visual Census-KA
multibeam sonar system
Type of sonar used to map the seabed. RLS
In particular, sharks feed aggressively on the large number of groupers present during spawning aggregations in June and July
Sharks are taking advantage of the large spawning aggregations to feed. MC
hydrophones
A microphone that detects sound waves underwater. RLS
Contrary to previous findings, our results highlight that sharks may overcome low local energy availability by feeding on fish spawning aggregations, which concentrate energy from other local trophic pyramids. Fish spawning aggregations are known to be targeted by sharks, but they were previously believed to play a minor role representing occasional opportunistic supplements.
An increase from the standard amount of fish in the area for reproduction purposes was believed to have an insignificant role in providing a reef shark's energy needs. Originally, sharks feeding on the greater amount of fish was thought of as an infrequent addition. -ASR
Generalized linear mixed models (GLMMs) and generalized additive mixed models (GAMMs)
Takes into consideration a number of variables from different distributions and includes fixed and random effects- KA
Detailed : https://stats.idre.ucla.edu/other/mult-pkg/introduction-to-generalized-linear-mixed-models/
Overall, sharks showed different degree of residency (mean ± SEM = 42.21% ± 7.75% of days present in the pass; range = 2.1%–95.9%; Table S3), with three transient (<20% residency), six semi-resident (20%–70% residency), and four highly resident (>70% residency) sharks (Figure S2).
The study showed that overall, there was a higher number of sharks observed that spent most of their time in the pass than there were that spent less of their time in the pass. YS & WT
trophic pyramid
a visual figure and/or explanation of the distribution of biomass through an ecosystem. -MSars
Previous research [9] reported that the slope of biomass by mass class cannot be steeper than 0.25 unless the food web system is subsidized; the slope we computed from Fakarava is 0.51
Describes the initial observation leading to the purpose of the study. --CGG
hectare
A metric unit equal to 10,000 square meters. Used commonly for large areas of land. -ASR
See this article in Metric Views for help to visual this size: http://metricviews.org.uk/2007/11/how-big-hectare/
pristine
It is a paleontological term which describes earliest period or states of life before human impact. YS
opportunistic supplements
This basically means that the sharks are attracted to large groups of spawning grouper because it is an easy opportunity to get a lot of food. -AWC
Sharks in the pass are using fish spawning aggregations as energetic subsidies to reduce the need for costly foraging excursions outside the pass boundaries, enabling this energy to be directed to other physiological functions.
The sharks can afford to stay in a low-energy environment because it experiences spikes in energy input as multiple species spawn throughout the year. --CGG
fish spawning aggregations
fish species grouping in a location to spawn. M.C
inverted biomass pyramid
A biomass pyramid refers to the difference in the amount of organisms on each trophic level, with producers (plants) having the highest biomass, then fewer herbivores, fewer carnivores, etc, with more prey than there are predators. When the pyramid is inverted, in this case, it means there are more predators than prey. -AWC
bioenergetics
Is the study of the energy conversion within an organism's metabolism. -MSars
We first constructed a high-resolution bathymetry map using a multibeam sonar system to characterize the study site (Figure 1) and georeferenced the aggregation of gray reef sharks, Carcharhinus amblyrhynchos, using a towed-diver methodology. Video-assisted underwater visual census surveys (n = 13), conducted as drift transects across the entire shark school, were used to provide a precise total shark census within the pass (June–December 2014).
A combination of the data collected from the sea floor structure (topography) and video surveys through transect lines were used in order to try to find a correlation between the habitat and the shark density. YS & WT
towed-diver methodology
A sampling method in which a diver is pulled along slowly underwater while holding onto a line connected to a boat. This method is useful for covering large areas of reef. - AWC
bathymetry map
Map of underwater features-SES
bathymetry map
A topographical map of the sea floor showing depth and structure through use of different colors. - WT & YS
acoustic telemetry
a way of remotely tracking the movement of a fish using tags that communicate with sound. -RKL
However, our results also suggest that when the spawning aggregation subsidies become scarcer during summer and metabolic rate increases due to warmer waters, sharks shift to investing in foraging excursions to escape low energy availability in the pass.
Warmer water and lack of fish spawning sites cause reef sharks to invest more time in searching for higher energy food.-SES
baseline
a point used to compare things against -RKL
acoustic telemetry
Tagging method that consists on getting information about the tagged fish through underwater sound signals.
Acoustic waves are converted into electrical signals that can be tracked to follow the position of the species. YS & WT
The consequence is sharks being forced to undertake energetically costly wider-range foraging as the only option to meet energy requirements
Reef sharks spend more energy searching for food due to overexploitation of fish spawning sites.-SES