scholarly journals Correcting Positional Errors in Shore-Based Theodolite Measurements of Animals at Sea

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Ophélie Sagnol ◽  
Femke Reitsma ◽  
Christoph Richter ◽  
Laurence H. Field
Keyword(s):  
New Zealand ◽  
Habitat Use ◽  
Marine Mammal ◽  
Positional Information ◽  
Physeter Macrocephalus ◽  
Sperm Whales ◽  
Vertical Angle ◽  
Position Accuracy ◽  
Wide Range ◽  
The Difference

Determining the position of animals at sea can be particularly difficult and yet, accurate range and position of animals at sea are essential to answer a wide range of biological questions. Shore-based theodolite techniques have been used in a number of studies to examine marine mammal movement patterns and habitat use, offering reliable position measurements. In this study we explored the accuracy of theodolite measurements by comparing positional information of the same objects using two independent techniques: a shore-based theodolite station and an onboard GPS over a range of 25 km from the shore-based station. The technique was developed to study the habitat use of sperm whales (Physeter macrocephalus) off Kaikoura, New Zealand. We observed that the position accuracy fell rapidly with an increase in range from the shore-based station. Results showed that the horizontal angle was accurately determined, but this was not the case for the vertical angle. We calibrated the position of objects at sea with a regression-based correction to fit the difference in distance between simultaneously recorded theodolite fixes and GPS positions. This approach revealed the necessity to calibrate theodolite measurements with objects at sea of known position.

Stable isotope analyses reveal seasonal and inter-individual variation in the foraging ecology of sperm whales

2020 ◽  
Vol 638 ◽  
pp. 207-219
Author(s):  
M Guerra ◽  
L Wing ◽  
S Dawson ◽  
W Rayment
Keyword(s):  
Stable Isotope ◽  
Individual Variation ◽  
Large Scale ◽  
Isotope Ratios ◽  
Physeter Macrocephalus ◽  
Sperm Whales ◽  
Foraging Patterns ◽  
Seasonal Differences ◽  
Top Predators ◽  
Wide Range

Studying inter-individual variation in foraging by top predators is key for understanding the ecology of their populations, while knowledge of seasonal variability in foraging helps explain temporal changes in habitat use and ecological role. We investigated the inter-individual and seasonal differences in stable isotope ratios of sperm whales Physeter macrocephalus in the temperate foraging ground of the Kaikóura Canyon, New Zealand. Isotope ratios of carbon and nitrogen were measured in 107 samples of sloughed skin from 37 individual males with a wide range of residency patterns and body lengths, sampled over 4 summers and 3 winters. Variability in individual isotope ratios was analysed with generalised additive mixed models. The whales’ residency patterns, but not body size, accounted for most heterogeneity of δ13C and δ15N. Specifically, whales that visited Kaikóura occasionally had more diverse and lower isotope ratios than more frequent visitors (by ca. -1‰ δ13C and -2‰ δ15N), likely reflecting a range of foraging habitats further offshore and/or south of Kaikóura Canyon. We suggest that these patterns reflect differences in large-scale foraging patterns within the population. In addition, whales sampled in winter had significantly lower values of δ13C than whales sampled in summer (by ca. -0.5‰), indicating seasonal differences in the use of food resources. Our results provide new insights into foraging patterns of sperm whales, and highlight the value of accounting for individual differences in the ecology of top predators.

Seasonal distribution and diving behaviour of male sperm whales off Kaikoura: foraging implications

2000 ◽  
Vol 78 (3) ◽  
pp. 407-419 ◽  
Author(s):  
Nathalie Jaquet ◽  
Stephen Dawson ◽  
Elisabeth Slooten
Keyword(s):  
New Zealand ◽  
Food Supply ◽  
Seasonal Distribution ◽  
Diving Behaviour ◽  
Physeter Macrocephalus ◽  
Sperm Whales ◽  
Non Invasive ◽  
Male Sperm ◽  
Adequate Food ◽  
Whaling Industry

Male sperm whales (Physeter macrocephalus) were the preferred target of the whaling industry between 1950 and 1985, but despite hundreds of thousands of kills, very little is known about their ecology. To partially redress this, we present data on residency, seasonal distribution, and diving behaviour of individually identified sperm whales off Kaikoura, South Island, New Zealand, gathered during 15 field seasons over 8 years. One hundred and thirty-six sperm whales were identified within the study area. A lack of statistically significant differences in the abundance of sperm whales between summer and winter, and among the 15 seasons of fieldwork, suggests an adequate food supply year-round. Significant differences in distribution between summer and winter suggest that off Kaikoura, male sperm whales may change their diet in response to fluctuations in prey biomass. Diving behaviour was also significantly different between summer and winter: sperm whales dived for longer, stayed longer at the surface, and travelled farther between consecutive fluke-ups in summer than in winter. Unlike female sperm whales, males at Kaikoura spent little time at the surface; they spent about 83% of their total time under water. This paper represent the most extensive non-invasive study of male sperm whales and provides new insights into their ecology.

Acoustically derived growth rates of sperm whales (Physeter macrocephalus) in Kaikoura, New Zealand

2013 ◽  
Vol 134 (3) ◽  
pp. 2438-2445 ◽  
Author(s):  
Brian S. Miller ◽  
Abraham Growcott ◽  
Elisabeth Slooten ◽  
Stephen M. Dawson
Keyword(s):  
New Zealand ◽  
Growth Rates ◽  
Physeter Macrocephalus ◽  
Sperm Whales

Assessing the vulnerability of organic matter to C mineralisation in pasture and cropping soils of New Zealand

Soil Research ◽  
2018 ◽  
Vol 56 (5) ◽  
pp. 481 ◽  
Author(s):  
Sam McNally ◽  
Mike Beare ◽  
Denis Curtin ◽  
Craig Tregurtha ◽  
Weiwen Qiu ◽  
...  
Keyword(s):  
New Zealand ◽  
Organic Carbon ◽  
Cold Water ◽  
Exponential Model ◽  
Hot Water ◽  
Environmental Perturbations ◽  
Wide Range ◽  
C Mineralisation ◽  
The Mean ◽  
The Difference

In New Zealand, pastoral soils have substantial organic carbon (OC) stocks, which may be vulnerable to loss from disturbance and environmental perturbations. We assessed OC vulnerability using two approaches. For the first approach, we postulated that the OC deficit of continuously cropped soils relative to nearby pastoral soils would provide a measure of the quantity of potentially vulnerable OC in pastures. As a test, soils were sampled to a depth of 15 cm at 149 sites and the total organic carbon (TOC) and particulate organic carbon (POC) contents were measured. The second approach involved measurement of OC mineralisation in a laboratory assay (98 day aerobic incubation at 25°C). For the pastoral soils, the mean TOC and POC was about twice that of the cropped soils. On average, 89% more OC was mineralised from the pastoral soils compared with the cropped counterparts. However, the quantity of OC mineralised in pasture soils was small relative to the potential for OC loss inferred from the difference in TOC between pastoral and cropped soils. Carbon mineralisation was explained using a two-pool exponential model with rate constants of the ‘fast’ and ‘slow’ pools equating to 0.36 ± 0.155 and 0.007 ± 0.003 day–1 respectively. The larger, slow OC pool correlated strongly with hot water extractable OC whereas the fast pool was related to OC extracted using cold water. Our results suggest that water extraction (using cold and hot water) can provide a rapid estimate of the quantity of mineralisable OC across a wide range of New Zealand soils.

scholarly journals Occurrence and distribution of cetaceans in São Tomé and Príncipe tropical archipelago and their relation to environmental variables

2009 ◽  
Vol 89 (5) ◽  
pp. 1071-1076 ◽  
Author(s):  
C. Picanço ◽  
I. Carvalho ◽  
C. Brito
Keyword(s):  
Bottlenose Dolphins ◽  
Humpback Whales ◽  
Tropical Region ◽  
Physeter Macrocephalus ◽  
Sperm Whales ◽  
Sao Tome And Principe ◽  
Wide Range ◽  
Rest Areas ◽  
Pilot Whales ◽  
Stenella Attenuata

São Tomé and Príncipe is an archipelago located in the Gulf of Guinea. This archipelago seems to be an important area for cetaceans, probably due to large concentrations of prey, as well as the existence of several small bays and shallow water that constitute preferred rest areas. In comparison to other areas of the world, little is known about cetacean communities in this archipelago. Boat-based surveys to record sightings of cetaceans were conducted between 2002 and 2005, which represents the first approach to study the occurrence of whales and dolphins in this tropical region. Sightings of humpback whales (Megaptera novaeangliae), bottlenose dolphins (Tursiops truncatus), pantropical spotted dolphins (Stenella attenuata), killer whales (Orcinus orca), sperm whales (Physeter macrocephalus) and pilot whales (Globicephala melas) were recorded. Cetaceans were found throughout a range of sea surface temperature between 24 and 29°C and a wide range of depths. Significant differences were found regarding the occurrence of some species. Humpback whales showed a preference for shallower waters between 20 and 100 m. Bottlenose dolphins occurred most commonly along the continental shelf (20 to 100 m) and pantropical spotted dolphins occurred in deep slope waters (>1000 m).

scholarly journals Convergent evolution in toothed whale cochleae

2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Travis Park ◽  
Bastien Mennecart ◽  
Loïc Costeur ◽  
Camille Grohé ◽  
Natalie Cooper
Keyword(s):  
Convergent Evolution ◽  
Habitat Type ◽  
Deep Ocean ◽  
Sperm Whale ◽  
Physeter Macrocephalus ◽  
Sperm Whales ◽  
Acoustic Environment ◽  
Wide Range ◽  
Beaked Whales ◽  
Cochlear Morphology

Abstract Background Odontocetes (toothed whales) are the most species-rich marine mammal lineage. The catalyst for their evolutionary success is echolocation - a form of biological sonar that uses high-frequency sound, produced in the forehead and ultimately detected by the cochlea. The ubiquity of echolocation in odontocetes across a wide range of physical and acoustic environments suggests that convergent evolution of cochlear shape is likely to have occurred. To test this, we used SURFACE; a method that fits Ornstein-Uhlenbeck (OU) models with stepwise AIC (Akaike Information Criterion) to identify convergent regimes on the odontocete phylogeny, and then tested whether convergence in these regimes was significantly greater than expected by chance. Results We identified three convergent regimes: (1) True’s (Mesoplodon mirus) and Cuvier’s (Ziphius cavirostris) beaked whales; (2) sperm whales (Physeter macrocephalus) and all other beaked whales sampled; and (3) pygmy (Kogia breviceps) and dwarf (Kogia sima) sperm whales and Dall’s porpoise (Phocoenoides dalli). Interestingly the ‘river dolphins’, a group notorious for their convergent morphologies and riverine ecologies, do not have convergent cochlear shapes. The first two regimes were significantly convergent, with habitat type and dive type significantly correlated with membership of the sperm whale + beaked whale regime. Conclusions The extreme acoustic environment of the deep ocean likely constrains cochlear shape, causing the cochlear morphology of sperm and beaked whales to converge. This study adds support for cochlear morphology being used to predict the ecology of extinct cetaceans.

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