Diseases in Marine Ecosystems

One Health Approach

The view that the health of people, env., and animals are all connected (transdisciplinary approach)

Useful aspects of disease

Regulates population, drives natural selection, shapes species interactions

Traditional view of disease ecology

More biodiversity leads to more disease (more potential hosts, vectors, reservoirs, and transmission pathways)

dilution effect view of disease ecology

Higher biodiversity leads to reduced disease (‘Less competent’ hosts dilute the pool of potential infection which disrupts infection chain)

What can cause an increase in disease

Changes in temp, pollution, weather events, PH

How does temp cause more disease

Stressed hosts, Increased pathogen growth & reproduction, Pathogen expansion/migration, new opportunities for invasive species to colonies & bring disease

How does severe weather increase disease

Stresses host, habitat damage, stirs up sediment and pathogens

How does habitat loss increase disease

Stresses hosts, loss of natural filtration/disease removal (bivalves, etc.)

How do toxins and pollution increase disease

Weakens immune systems, eutrophication (algal blooms)

How does climate change impact hosts

Microbiome dysbiosis, immune dysregulation, metabolic exhaustion, stress & compromised thermal tolerance, altered range/distribution

How does climate change impact pathogens

Faster multiplication, enhanced virulence, invasive potential, higher transmission rates, year-round growth, novel infection reservoirs, range expansion & abundance

How does climate change impact the marine environment

Higher temp, acidification, deoxygenation, extreme weather event (more storms & greater wave action), sedimentation, freshwater flux

Endoparasites

Internal

ectoparasites

External

Nematodes

roundworms

Trematodes, monogeneans

Flatworms

Cestodes

tapeworms

Annelids

Leeches

Parasitic protozoa are…

unicellular eukaryotes, very diverse

Parasites are…

Usually, very host specific

If hosts are endangered…

so are the specific parasites

How many viruses per ml of sea water

10,000,000

How many bacteria in ml of sea water

1,000,000

How many species of bacteria in one drop of sea water

~100

what causes non-infectious diseases

Changes in temp, salinity, PH, species assemblages, habitat, decreased food availability, exposure to toxins, genetic factors

Causes of harmful algal blooms

Nutrient run-off, climate change, thermal pollution

How are diseases transported by humans

Ballast water, imported bait, aquaculture, recreational fishing, water sports

Methods of preventing and responding to disease outbreaks

Policy & regulation, Marine biosecurity & response plans, fishery closures, aquaculture health management plan, climate mitigation

Microbe definition

A microscopic organism

Positive roles of microbes in marine ecosystems

Primary production, nutrient cycling, population management, decomposition, bioremediation, symbiosis

Phytoplankton definition

The autotrophic (self-feeding) components of the plankton community

Phytoplankton are primarily comprised of…

Cyanobacteria & protists

Phytoplankton produce what % of the ocean’s primary productivity

~98%

How much of the world’s primary production do phytoplankton produce

about half

How much of the planet’s oxygen do phytoplankton produce

half

3 components that make decomposition important

Break down decaying organic waste, return nutrients to the ecosystem, keep the seabed clean and tidy

Bacteriophages definition

viruses that infect bacteria

What is the most common and diverse group of organisms on the planet

Bacteriophages

What are the five phases of how a bacteriophage infects a bacteria

Attachment, penetration, biosynthesis, maturation, lysis

Attachment phase

The phage attaches to the surface of a host

Penetration phase

The viral DNA enters the host cell

Biosynthesis phase

Phage DNA replicates and phage proteins are made

Maturation phase of a bacteriophage

New phage particles are assembled

Lysis phase

The cell lyses (ruptures), releasing the newly made phages

How do bacteriophages assist in bacterial evolution

Horizontal gene transfer

Bioremediation definition

Any process wherein a biological agent (bacteria, microalgae, fungi, plants) is employed for removing environmental pollutants from air, water, soil, etc.

Microbiome definition

The collection of all microbes, such as bacteria, fungi, viruses, and their genes, that naturally live on our bodies and inside us.

Holobiont definition

A collection of species that have complex interactions, together forming a discrete ecological unit

How does the microbiota benefit in the host

Shelter, nutrient provision

How does the host benefit with the biota

Digestive assistance, nutrient provision, pathogen resistance, immune priming and development, environmental adaptation, abiotic stress tolerance.

Factors that influence microbiome composition

Environment, biogeography, host phylogeny, morphological niche

Dysbiosis definition

a disruption to the microbiome resulting in an imbalance in the microbiota, changes in their functional composition and metabolic activities, or a shift in their local distribution

Causes of dysbiosis

Pollutants, climate change, habitat alteration, diet change, poor host health

Results of dysbiosis for host

Increased disease susceptibility, reduced host development, necrosis and tissue damage, impaired function, immune system disruption

Ecological consequences of dysbiosis

Ecosystem instability, less resilient to climate change and anthropogenic pressures, disruption of biogeochemical cycles, impacts on aquaculture

Hygiene hypothesis

Early exposure to microbes/parasites is protective against developing immune disease

‘Old friends’ hypothesis

Builds on ‘Hygiene hypothesis’ by specifying that the microbes involved are a set that we have co-evolved with

Ways of assessing a microbiome

Substrate swab, surface swab, tissue sample, sea water filter, soil sample, fecal samples, body fluids