Red-Pelaged Harbour Seals, in Humboldt County, California: why some Seals Rust

In this paper we present data on the occurrence of red-pelaged harbour seals, Phoca vitulina, at a haul-out in Humboldt County, California. Density of red seals ranged from 4% to 17.5% (n=21) and was comparable to that reported for San Francisco Bay, being the highest documented worldwide. The red colouration is the result of natural inorganic iron oxide/hydroxide pigments (limonite), which are present in small patches on the beach sand of the seals haul-out at the mouth of the Mad River. Thorough analysis of the river water and ocean water excluded these as possible sources for the iron oxide/hydroxide pigments. We found that the manmade reinforcement of the river bank adjacent to the haul-out consisted of greenshist boulders with a very high iron content. Weathering of these rocks produces red iron oxide/hydroxide particles which are then redeposited by rain or river action in small patches across the haul-out. Seals receive their red colouration through direct physical contact with these patches. SEM examination showed that these particles can adhere lastingly to the seals’ hair. Other studies provide reason for concern that this situation may detrimentally impact the seals’ health.     

Geophysical Study of Annular Well Seals

Geophysical logging was conducted in 35 in-service water and monitoring wells installed in unconsolidated sediments using a downhole ultrasonic probe to assess how sealant type, construction method, and site geology affect annular seals. Collapsed sand and gravel was frequently detected in the annulus of wells constructed with mud-rotary methods, precluding the placement of sealant and, in some wells, potentially providing a preferential pathway for contamination. High-solids bentonite grout appeared to create high-quality seals when formation materials did not collapse into the annulus. Seals composed of bentonite chips and pellets remained intact when hydrated upon placement; those not hydrated during placement remained dry and porous, posing a risk of surface water infiltration. Seals made with cement-bentonite grout were generally unsaturated and possibly cracked. Analysis of the data suggests that well designers should specify a construction method that minimizes collapse of the formation to ensure that the sealant is placed where intended. When collapse is avoided, high-solids bentonite grout and hydrated bentonite chips and pellets appear to yield intact seals. However, bentonite chips and pellets may not hydrate adequately in the annulus unless hydration water is added during installation. When cement-bentonite grouts are used, the well designer should ensure that the grout will remain intact and plastic after installation.     

Bioaccumulation of radiocaesium in Arctic seals

Seals are high trophic level feeders that bioaccumulate many contaminants to a greater degree than most lower trophic level organisms. Their trophic status in the marine food web and wide-spread distribution make seals useful sentinels of arctic environmental change. The purpose of this investigation is to document the levels and bioaccumulation potential of radiocaesium in high latitude seal species for which data have not previously been available. The study was carried out on harp, ringed, and bearded seals caught north of the island archipelago of Svalbard (82°N) in 1999. The results are then compared with previous studies in order to elucidate factors responsible for bioaccumulation in Arctic seals. Concentrations of ¹³⁷Cs were determined in muscle, liver and kidney samples from a total of 10 juvenile and one adult seal. The mean concentration in muscle samples for all animals was 0.23±0.045 Bq/kg f.w. ¹³⁷Cs concentrations in both liver and kidney samples were near detection limits (≈0.2 Bq/kg f.w.). The results are consistent with previous studies indicating low levels of radiocaesium in Arctic seals in response to a long term trend of decreasing levels of ¹³⁷Cs in the Barents Sea region. Bioconcentration factors (BCFs) estimated for seals from NE Svalbard are low, ranging from 34 to 130. Comparing these values with reported BCFs for Greenland seals from other sectors of the European Arctic, we suggest that the combination of physiological and ecological factors on radiocaesium bioaccumulation is comparable among different Arctic seal populations. The application of this work to Arctic monitoring and assessment programs is discussed.     

Effects of oil pollution on breeding Grey Seals

Marine mammals are probably frequently exposed to floating oil but little is known about the effect oil pollution has on them. Oil stranded on the shore in Pembrokeshire, West Wales in September 1974 coincided with the start of the Grey Seal breeding season there. Observations have been made on the effect the oil had on the newborn pups and their mothers.     

Field Evaluation of Ultrasonic Method for Assessing Well Seals

Field tests were conducted in three boreholes using an ultrasonic testing method to evaluate its ability to assess contact between the seal and riser (casing). The ultrasonic method is used inside the riser without disturbing the riser, seal, or formation soil. The risers were 50-mm-diameter (2-inch) Schedule 40 steel pipes that are used for ground water monitoring wells. Different types of seals were placed around the risers and defects were purposely introduced in the seals to test the ultrasonic method. The ultrasonic response changed as the neat-cement seals cured or hydration of the bentonite seals changed. When adequate moisture was not available, the bentonite seals deteriorated, losing contact with the riser. When adequate moisture was available, however, the seals swelled into contact with the riser. Both conditions were detected with the ultrasonic method. The method also detected the intentional defects, as well as defects that were not intended. The boreholes were excavated to compare results of the ultrasonic tests with the actual condition of the seals. The condition of the seals agreed well with the results of the ultrasonic tests.