Is Marine Mammal Health Deteriorating? Trends in the Global Reporting of Marine Mammal Disease

Abstract

A recent rise in the reporting of diseases in marine organisms has raised concerns that ocean health is deteriorating. The goal of this study was to determine whether or not there has been a recent deterioration in marine mammal health by investigating the trends in disease reports over the past 40 years (categorized by the method of study, the species affected, and the etiology of the disease) and by exploring the changes in frequency of mass mortality events among marine mammals reported in the United States since 1978. The number of papers on marine mammal disease published each year has increased since 1966, although the annual publication rate appears to have stabilized since $1992. Those published in the 1960s and 1970s were largely about helminth and bacterial disease, those investigating viruses emerged in the late 1970s and increased in the 1980s and 1990s, whereas protozoal diseases and harmful algal toxins were largely not reported until the 1990s. The annual number of mass mortality events in the U.S. approximately doubled between 1980 and 1990 but since 2000 has been between seven and eight events per year. Causes of mass mortality events have included biotoxins, viruses, bacteria, parasites, human interactions, oil spills, and changes in oceanographic conditions. Events due to biotoxins appear to be increasing, but the change in the frequency of mass mortality events from other causes over the past 40 years cannot be determined from the available published literature due to changes in marine mammal abundance, inconsistencies in effort and extent of resources for pathological investigation, and advances in technology that have allowed improved detection of pathogens and toxins in more recent years. To ensure future information on the true incidence of marine diseases and their underlying causes is more reliable, specific and directed marine health monitoring programs, well-equipped stranding networks, and dedicated diagnostic laboratories are needed.

An Economical Custom-Built Drone for Assessing Whale Health

“…There are widespread concerns about the health of marine mammal populations in the face of global anthropogenic stressors (Gulland and Hall, 2007). Yet health assessments typically involves collecting samples from stranded animals, which are often biased as these animals are most likely to be health-compromised (Geraci and Lounsbury, 2005).…”

Complementary approaches to diagnosing marine diseases: a union of the modern and the classic

“…genomics, proteomics and metabolomics), optics, analytical chemistry and molecular biology. However, to fully understand the disease process and to place it within an ecological context, results from these novel methods must be interpreted alongside data collected by more classic or traditional means such as gross observation of lesions, transect surveys, microscopic observation of cellular changes, disease transmission assays in experimental conditions, histopathology and microbiology [18,19]. An effective approach for disease diagnosis and identification also requires examination of the problem at multiple levels of biological complexity (figure 2), starting with an environmental assessment and continuing to the genome level.…”

Dynamics of Vibrio with Virulence Genes Detected in Pacific Harbor Seals (Phoca vitulina richardii) Off California: Implications for Marine Mammal Health

“…Marine mammals are sensitive to changing environmental conditions and can serve as sentinels for ecosystem health [11,13,35,60]. Long-term monitoring of marine mammal health includes measuring contaminants, trace elements, biotoxins from harmful algal blooms, baseline blood values, and prevalence of infectious disease so that deviations from normal values may be detected [10,12,32,33,[35][36][37][38].…”

“…Long-term monitoring of marine mammal health includes measuring contaminants, trace elements, biotoxins from harmful algal blooms, baseline blood values, and prevalence of infectious disease so that deviations from normal values may be detected [10,12,32,33,[35][36][37][38]. Cumulative effects of one or more of these factors may have contributed to the deterioration of marine mammal health [10,11,13,35]. Because infectious marine diseases appear to be increasing and are of immediate concern to marine mammal health, the dynamics and virulence potential of aquatic microbes should be investigated [4,10,28,38,48,75].…”