Transcript Diseases and Conservation - University of California, Davis

Diseases and Conservation
Emerging Diseases
• New or “emerging” diseases are showing up
in marine systems (some evidence that they
are new)
• Some of these are linked to pathogens
outside of the marine environment
(terrestrial, human)
• These pathogens can have devasting
impacts in some cases
• Often there is little of no evolutionary history
and little of no resistance to new diseases
Sea Fans and Aspergillosis
• In the 1990s, scientists began to see dieoffs
of gorgonians (sea fans) in the Caribbean
(Harvell et al. 1999)
• It was caused by Aspergillus sydowii a
fungal infection that has terrestrial origins
• It has affected many species and contributed
to substantial losses in many areas
• This pathogen is believed to be derived from
soil fungi and may have developed from
increased terrestrial runoff into coastal
oceans
Sea Fans and Aspergillosis
Sea Fans and Aspergillosis
Sea Fans and Aspergillosis
Sea Fans and Aspergillosis
Sea Fans and Aspergillosis
Sea Fans and Aspergillosis
Corals and Coral Disease
• Many diseases of corals have increased
significantly over the last several decades
• These may have been exacerbated by human
impacts (warming, nutrients)
• Many diseases have identified pathogens
including black band, white band, white pox,
yellow band, etc.
• Others such as coral bleaching may or may
not
Corals and Coral Disease
Coral Diseases
• Among the most devastating have been the
diseases of acroporid corals in the
Caribbean
• Acroporid corals (staghorn, elkhorn corals)
were the most common, erect, reef building
corals in the Caribbean
– Elkhorn coral on reef crest to 5 m depth
– Staghorn coral from 5-15 m depth and backreefs
• These have largely disappeared over the last
decade due in large part to diseases like
white pox (south Florida) and white band
diseases (Belize) (Aronson et al. 2002)
Coral Diseases
Coral White Band Disease
Coral White Pox Disease
Coral White Pox Disease
Coral White Pox Disease
• Acroporid corals in the Florida Keys have
declined by more than 70% in the last decade
due to white pox disease
• This has also likely increased as the result of
declining water quality (temperature,
nutrients)
• White pox is a disease is caused by a
bacteria that is found in the human gut
Serratia marcescens (Patterson et al. 2002)
• It is possible/likely that the increased input of
sewage in water of south Florida have
contributed to this disease outbreak
Coral White Pox Disease
Coral White Band Disease
• Aronson et al. (2001) documented the
declines of acroporid corals along the
Belizean barrier reef area
• They focused particularly on the rich
lagoonal reefs that had been hit by
white band disease (and hurricanes)
• The used core data to determine if
these dramatic changes due to disease
had ever happened before
Coral White Band Disease
• They found dramatic declines in acroporids
followed by rapid increases in agaricid corals
(Agaricia) and an overall decline in coral
cover
• The core data also showed a strong signal of
this recent transition from acroporid to
agaricid corals
• They used the older core data to show that
this decline in acroporids and transition to
agaricid corals had never happened in the
last 3000 yrs.
Coral White Band Disease
Sea Otters and Disease
• Connors and colleagues (UC Davis Vet
School) surveyed 105 dead otters
(necropsies) between Feb. 1998 and July
2001
• Using only recently killed otters (<4 days)
they surveyed a range of causes of death
including sharks attacks, shooting, cardiac
disease and common diseases
• Two parasites, acanthocephalans and
Toxoplasma gondii were at the top of the list
Sea Otters and Disease
Sea Otters and Disease
Sea Otters and Disease
• Acanthocephalans (Profilicollis sp. And
Corynosoma enhydri) can cause
peritonitis (internal inflamation)
• It was the primary cause of death in
17% of cases and contributing cause in
40%
• Clustered around southern end of
Monterey Bay
Sea Otters and Disease
• There was also high mortality due to
parasitic infection of Toxoplasma gondii
• Infection results in encephalitis (brain
inflamation)
• This was the primary cause of death in 17%
of deaths and contributing cause in nearly
40% as well
• High proportion of sharks attacks involved
otters with encephalitis
• High concentration deaths in the Morro Bay
area
Harbor Seal Epidemic
Harbor Seals and Phocine
Distemper Virus
• Phocine distemper virus (PDV) killed 23,000
and 30,000 harbor seals (Phoca vitulina) in
northern Europe in 1988 and 2002
• Another species, Grey seals were likely the
reservoir and vector for the disease
• Organochlorine pollutants including PCBs
were implicated as a contributing factor in
the earlier outbreak
• These pollutants have been implicated in
other marine mammal epidemics including
dolphins in eastern U.S.
Manatees and
Disease
• Pathogens of manatees further endangered
an already desperate species
• In 1996, a disease resulted in the death of
nearly 150 manatees in south Florida
(Bossart et al. 1998)
• This dieoff was linked to a outbreak of a toxic
dinoflagellate Gymnodinium breve
• Constant exposure to the brevetoxin resulted
in nasal hemorrhage and pulmonary edema
(swelling) contributing to death
Manatees and
Disease
• Diseases are not the main cause of death for
manatees
• Death due to contact with boat propellers is
still the main cause (Marmontel et al. 1997)
• However, a PVA of manatees shows that a
10% increase in adult mortality will result in
the ultimate extinction of manatees
• Disease can add substantially to that
increased probability of adult death
Oyster Diseases
• Oysters are important foundation species in
estuaries and positively affect water quality
and many aspects of ecosystem function
• Oysters have been over harvested but have
also been the target of many pathogens and
parasites
• These diseases have not only impacted
harvesting but have led to dramatic changes
in many estuarine ecosystems
Oyster Diseases
Lafferty et al. 2004
Oysters and Disease
• Up until 1959-1960 oysters in Chesapeake
Bay were an important fishery and a
foundation species
• Two diseases showed up nearly
simultaneously: Dermo and MSX
– Dermo (Perkinsus marinus) is a directly
transmitted disease among oysters and other
bivalves MSX (Haplosproridium nelsonii) is a
sporozoan that has an unknown life cycle (isn’t
transmitted between oysters)
Oysters and Disease
• MSX first showed up in Delaware Bay and
may have been introduced there (with
oysters?)
• Dermo likely came up with oysters from the
Gulf of Mexico
• Within a couple years, 90-95% of the oysters
in Chesapeake Bay were gone
• Only higher salinity areas in the lower bay
survived (pathogens don’t do as well)
Oysters and Disease
• Other species can distribute Dermo
• Mudcrabs (several species of xanthids) and
Boonea impressa a parasitic snail can feed
on dead oysters and transmit it to other
oysters
• Other bivales (18 at last count) can be host to
Dermo including the recently introduced
Crassostrea ariakensis introduced from Asia
• It may be a reservoir for the disease
increasing the impacts it has on the native
eastern oyster Crassostrea virginica
Disease and Aquaculture
• In addition to introduced species
themselves causing problems, also
parasites and diseases associated with
introductions
• Quarantine facilities only work for
species intentionally brought in
• Difficult to know if “new” disease was
undiagnosed or actually introduced
Mass Mortality of Sardines
• Aquaculture is suspected of producing
one of the worst mass mortalities of a
commercial fishery
• Huge dieoffs of sardines Sardinops
sagax in South Australia occurred in
1995 and 1999
• Nearby tuna farming and the import of
frozen (and apparently infected)
sardines is believed to be responsible
Abalone Parasites
• The sabellid
polychaete
Terebrasabella
heterouncinata
• It is native to
abalone in South
Africa where they
are apparently more
resistant
• It was spread to 18
abalone farms
around California
early 1990s
Abalone Parasites
• Populations of the
abalone parasite were
found near Cayucos,
CA (north of Morro
Bay) in 1996
• The eradication
program involved
parallel eradication of
parasites from
cultured stock
• Involved reducing the
population of adult
parasites and
reducing the most
susceptible native
hosts
Abalone Parasites
• 1.5 million turban
snails were removed
from intertidal
habitats
• Staff of local abalone
farms, CDFG staff,
volunteers, university
students/staff with
semiannual followups
(not recently)
• Found again recently
in one educational
facility and two
production facilities
• Possible it is in
natural populations
Future Disease Increases
• An important issue is whether there is a
long-term trend in the frequency of disease
• Data suggest for some taxa that there is
clearly an increasing trend
• The data are hard to gather and they are
biased in some cases by increased scientific
study and interest
• To what degree other human impacts are
contributing to this increase is uncertain
Future Disease Increases
Future Disease Increases