Physiological Changes

Human activities can also affect the physiology of marine mammals, which would help us understand if those changes may lead to changes in survival and reproductive rates of the resident populations.

Genetic health

We will do “genotyping-by-sequencing” of bottlenose dolphins from the Azores, Madeira, mainland Portugal (Sado estuary included), Galicia, Gulf of Cadiz and the Strait of Gibraltar to infer the fine-scale population substructure in order to define the different management units (MUs) present in the region, inbreeding levels, assessing their historical dynamics and directional patterns of connectivity; and using markers potentially under selection, information on the “genetic health” of the different populations and sampled individuals can be obtained.

Genetic variation is the basis of evolution, allowing organisms to adapt to changing environmental conditions. Migration and point mutation are known to increase genetic variation, but selection by disease or climate change, which will decrease survival rates, can cause a bottleneck effect and decrease genetic diversity. Today, the use of genome-wide markers, such as Single Nucleotide Polymorphisms (SNPs), at the population level provides large numbers of genetic markers and therefore allows the description of genetic diversity. Recent studies have highlighted their potential to infer population structure (particularly at fine spatial scales where population structure may be weak), to estimate gene flow and to examine population connectivity which was previously unidentified under traditional approaches. These data allow us to (i) identify genetic management units (MUs) (ii) reconstruct major events of the demographic history of populations (iii) identify genomic regions under selection, (iii) levels of inbreeding.

In order to obtain the best conservation outcomes for many species, it is necessary to consider the division of populations into smaller management units (MUs). MUs should be based on our best understanding of the structure of biological populations and any ecological differentiation within such populations. The MUs need to be assessed with consistency for the key cetacean species across all Portuguese waters. In these terms, the most representative species is the bottlenose dolphin, mainly because of its widespread distribution across Portuguese waters.

Contaminants

Marine mammals can also be used as pollution indicators. Persistent organic pollutants, such as polychlorinated biphenyls (PCBs), several chlorinated pesticides and DDTs, reach the marine organisms mainly through the food chain (biomagnification). Because of their physiochemical properties these compounds accumulate in fatty tissues of the body (bioaccumulation). Particularly significant is the carry-over of part of the body burden of females to their neonates, by prenatal trans-placental transfer and postnatal transfer via lactation. We are still lacking information about their levels and impact on oceanic cetaceans where levels are expected to be lower than near the European continent.

META will measure several PCBs congeners levels in bottlenose dolphins from the Azores, Madeira and mainland Portugal, sperm whales from the Azores and short-finned pilot whales from Madeira

Stress hormones

In order to better estimate the long-term impact of WW, stress hormone levels will be measured. In Madeira, WW activities occur year round. However, bottlenose dolphins and pilot whales distribution encompasses both within and outside the WW area. Meanwhile in the Azores WW is a seasonal activity which gives the opportunity to also sample sperm whales when no WW activity is going on.

In both Madeira and the Azores, stress hormones will be measured with two methodologies. We will collect a blow (exhaled air) from the animal using a pole or a drone that is equipped with a Petri dish that will retain the droplets of the blow from which hormones can be extracted. Secondly we will analyse hormone levels in blubber of live cetaceans. The stress hormone levels of individuals sampled within and outside WW area will be compared.