Soundings: the Newsletter of the Monterey Bay Chapter of the American Cetacean Society. 2013

Issues January - November/December 2013. (PDF contains 96 pages

Soundings: the Newsletter of the Monterey Bay Chapter of the American Cetacean Society. 2012

Issues January - November/December 2012. (PDF contains 88 pages

Pelagic deep-sea metazoan biodiversity and ecology revealed by environmental DNA analysis in combination with other censuses

The deep sea (> 200 m) not only represents the largest habitat on earth, but also has the highest faunal biomasses and greatest number of individual organisms. While the deep sea provides humans with substantial services, its ecosystems remain poorly studied. Logistical and technical challenges to sample deep-sea ecosystems as well as organisms’ avoidance behavior to underwater gear stress the need for alternative techniques. In this thesis, I focused on a relatively novel tool in deep-sea biology; environmental DNA (eDNA) analysis. Environmental DNA is genetic material that organisms shed into their environment. This eDNA can be assigned to a specific taxon and provides information on species presence, diversity and distribution without the need to encounter or capture the source animal. The first objective of this thesis was to develop a pipeline to collect diversity and distribution data on deep-sea cephalopods with eDNA analysis from water and sediment samples. The second objective was to establish biodiversity baselines and distribution patterns of key organisms in the deep sea and to put these patterns into an ecological context. The third objective of this thesis was to identify cephalopod and fish taxa that potentially contribute to the vertical transport of carbon. This thesis showed that eDNA can be used successfully in the assessment and monitoring of deep-sea pelagic metazoans in hotspots of diversity and climate change. Especially when eDNA analysis is analyzed in different kinds of samples and used in combination with other techniques, it can help to answer ecological questions and ultimately contribute to aid in conservation of deep-sea habitats

VARIABILITY IN COASTAL SHARK POPULATIONS ACROSS MULTIPLE SPATIOTEMPORAL SCALES

Variability across spatiotemporal scales has been recognized by ecologists as a fundamental issue in understanding ecosystem dynamics. Sharks emerged as a conservation concern as their populations declined and their influence on marine ecosystem dynamics became apparent. Efforts to better manage and understand shark populations and their response to anthropogenic pressures have been hindered by a lack of understanding of patterns across multiple scales of time and space. This dissertation aimed to describe patterns of variability in coastal shark populations across multiple spatiotemporal scales. Chapter 1 exploits a 45-year time series of shark monitoring to describe patterns of seasonality in the coastal shark community in Onslow Bay, North Carolina, and how seasonality shifted over long timescales (interannual-decadal). Seasonal turnover in coastal shark community composition was correlated with temperature changes, with spring/autumn species appearing first and subsequently being replaced by summer species before appearing again in autumn; both transitions occurred at approximately 25 °C. On interannual scales, this seasonal pattern was overshadowed by increases in abundance of the Atlantic sharpnose shark (Rhizoprionodon terraenovae), a non-seasonal species caught during all months of sampling. Chapter 2 utilizes the long-term data set to investigate within-species size structure over four decades. My analyses suggest declining trends in size for all species analyzed, with the strongest evidence for size declines in two small coastal shark species, Atlantic sharpnose shark and blacknose shark (Carcharhinus acronotus). These results provide insight on assemblage-level responses to anthropogenic pressure via environmental or genetic mechanisms. Chapter 3 employs acoustic telemetry to decipher bonnethead shark (Sphyrna tiburo) movement and behavior (e.g., residency and habitat use) over multiple spatiotemporal scales. My results suggest individual bonnethead sharks show fidelity across years to specific areas within estuaries in North Carolina and Georgia during seasonal residency and have affinity for areas nearest inlets. Finally, Chapter 4 evaluates shark detection probabilities from aerial drone surveys and how these were affected by environmental conditions in a temperate estuary. Shark detection from drone surveys was most influenced by depth, wind speed, and time of day; the highest detection probabilities occurred at shallow depth, low wind speed, and mid-day flight times.Doctor of Philosoph

Spatial and Temporal Variation of Reef Fish Assemblages in the Galapagos Archipelago: The Influence of Biogeography, Management and ENSO

I investigated the spatial and temporal distribution of Galapagos fish assemblages using diversity, abundance, and length data from baited remote underwater stereo-video systems. I generated information describing the ecology and status of finfish populations in relation to key natural and anthropogenic pressures. This information has local and global implications, including highlighting the unique values of the Galapagos archipelago for biogeography research. I suggest possible management actions to improve the status of local fish populations

Soundings: the Newsletter of the Monterey Bay Chapter of the American Cetacean Society. 2009

(PDF contains 88 pages.

Behavioural ecology of fishermen and odontocetes in a depredation context

The thesis assessed captains’ behaviour within a context of depredation. Additionally, this thesis described for the first time longlines depredation on the seafloor. Altogether, the findings suggest interesting leads to quantify the impact of depredation on fisheries and bring important insights for mitigation measures

Fish behavior and its use in the capture and culture of fishes

Fishery management, Behaviour, Food fish, Fish culture, Conferences