Disease & Stressors

  • Challenge: relatively little-studied

  • Import aspect of host-population regulation

    • not really impacted by humans

  • Factors

    • what are they?

    • how have they changed?

Parasite vs Pathogen

  • A parasite is an organism that lives in or on an organism at the host’s expense

    • protozoans and helminths

    • most are prokaryotic

    • macroscopic

    • not all cause disease in the host organism

  • Pathogen is an agent that causes a disease in a host

    • lives inside a host

    • bacteria, fungi, virus, prions, protists, and parasites

    • Eukaryotic organisms

Pathogen → host

→ either no infection or infection

→ if infection, disease or no disease

→ if disease, acquired immunity

Infection doesn’t always mean disease.

Steller Sea Lions

  • Eumetopias jubatus

  • Culprit: Nematode parasite

  • Gastrointestinal ulceration

  • Too much of a good thing (higher temps)

Terminology

  • Intermediate host

    • organism that supports a parasite during its asexual stage

  • Definitive host

    • organism that supports a parasite during its sexual stage

  • Oocyst

    • infection stage for the next host in a parasite’s life cycle

  • Reservoir

    • habitat in which an infectious agent normally lives, grows, and multiplies. includes humans, animals, and the environment

  • Vector

    • a living organism that spreads infectious pathogens and parasites to other organisms. vectors can be arthropods like tickets or other animals

Multifactorial nature of disease and stressors

Eastern Oyster

  • Culprit: protist parasite

  • Dermo disease

  • Northward moving trend due to increasing trend in winter water temperatures

  • More disease in costal systems

  • Disease lowers reisstance to other stressors

  • Complex effects

  • MSX (suppressed in colder temperatures)

American Lobster

  • Culprit: bacteria

  • “Epizootic shell disease”

  • Deep lesions that render susceptibility to other co-infections

  • Linked to warming temperatures in NE waters

Coral

  • have a symbiotic relationship with algae, change color when they die

Infection Dynamics: Virulence

  • how much affect the virus has

  • it phases out over time

  • Phenotypic plasticity and adaptation are two mechanisms that make it possible for organism's’ performance curves to shift such that a stressful environment is no longer experienced as __ instead of a new range of conditions provokes a stressor

  • Causation vs Association

  • Resilience is the tipping point

    • ability to endure and recover from stress without changing into a fundamentally different thing

    • factors influencing it: large population, migratory, behavioral plasticity, health

  • Host-pathogen dynamics

Disease Process

  • Reservoirs

  • Transmission: horizontal by waters via carriers, vertical via offspring

  • Pathogenestis: entry point of host by pathogen

  • host/geographic range

  • environmental factors

  • “epizootiology” the sum of the factors controlling the occurrence of the disease pathogen of animals

Strategies for Managing Marine Disease

  • increasing biosecurity

  • Spillback cutoff, cut off feedback loop

  • Natural ecosystem filters

  • Habitat conservation

  • Endangered species list

  • Diagnostics

  • Red List

  • IUCN

How to Elicit Human Interest: Ecosystem Services

  • provisioning services

  • regulating services

  • cultural services

  • supporting services

One Health Paradigm

  • Overlap between humans, wildlife, and domestic/urban animals

Conservation Challenges

  • improve measurement and monitoring of pollutant/pathogen (PP) distributions at various scales

  • improve knowledge of dynamics of transport/transformation of PPs int he environment

  • Improve assessment of PP exposure and risk to humans

  • Requires integrated, interdisciplinary system approach