Contaminant Loads And Hematological Correlates In The Harbor Seal (Phoca vitulina) Of San Francisco Bay, California

Abstract

An expanding body of research indicates that exposure to contaminants may impact marine mammal health, thus possibly contributing to population declines. The harbor seal population of the San Francisco Bay (SFB), California, has suffered habitat loss and degradation, including decades of environmental contamination. To explore the possibility of contaminant-induced health alterations in this population, blood levels of polychlorinated biphenyls (PCBs), dichlorodiphenyldichloroethylene (DDE), and polybrominated diphenyl ethers (PBDEs) were quantified in free-ranging seals; relationships between contaminant exposure and several key hematological parameters were examined; and PCB levels in the present study were compared with levels determined in SFB seals a decade earlier. PCB residues in harbor seal blood decreased during the past decade, but remained at levels great enough that adverse reproductive and immunological effects might be expected. Main results included a positive association between leukocyte counts and PBDEs, PCBs, and DDE in seals, and an inverse relationship between red blood cell count and PBDEs. Although not necessarily pathologic, these responses may serve as sentinel indications of contaminant-induced alterations in harbor seals of SFB, which, in individuals with relatively high contaminant burdens, might include increased rates of infection and anemia.

A three‐generational study of In ovo exposure to PBDE‐99 in the zebra finch

“…Hematocrit in ranch mink (Mustela vison) exposed to a PBDE mixture was reported to be significantly lower compared with control mink [36]. Neale et al [37] found erythrocyte level to be inversely correlated to PBDE concentrations in harbor seal (Phoca vitulina). Based on those contradictory results for birds and mammals, we suggest that the blood system of a bird may be less sensitive to the effects of PBDE exposure, possibly because of hematological differences between those taxa [29].…”

PAH‐ and PCB‐induced Alterations of Protein Tyrosine Kinase and Cytokine Gene Transcription in Harbor Seal (Phoca Vitulina) PBMC

“…Altered immune parameters associated with environmental exposure to PAHs and PCBs have been reported for several species of pinnipeds and cetaceans and include reduced antigen-specific antibody responses, depressed T-lymphocyte proliferative responses to mitogen, depressed plasma retinol, increased white blood cell count and depressed red cell parameters, and frequent infections with mildly pathogenic bacteria and high rates of cancer (Martineau et al 1994, Lahvis et al 1995, Beckmen et al 2003, Jenssen et al 2003, Neale et al 2005. Experiments in which captive harbor seals were fed heavily-contaminated (especially with PCBs) fish also supported a hypothesis of contaminant-induced immunological impairment.…”

Polychlorinated biphenyls (PCBs) and their hydroxylated metabolites (OH-PCBs) in livers of harbor seals (Phoca vitulina) from San Francisco Bay, California and Gulf of Maine

“…Since marine mammals such as seals are positioned at the top of the marine food web and have a relatively long life span (25-30 years), they are exposed to organochlorines (Neale et al, 2005a;Shaw et al, 2005) and are consequently vulnerable to endocrine disruptive effects such as reproductive impairment (Reijnders, 1986;Reddy et al, 2001), cancer (Martineau et al, 2002;Ylitalo, 2005), thyroid alteration (Sormo et al, 2005;Tabuchi et al, 2006), and immune suppression/infectious diseases (Ross, 2002;Beckmen et al, 2003;Hall et al, 2006;Hammond et al, 2005). PCBs are stored in the insulating blubber (lipid) and can be subsequently remobilized to the blood through lipid metabolism during the seasonal fasting (Debier et al, 2006), posing a health risk.…”