Diseases and Conservation. Emerging Diseases New or “emerging” diseases are showing up in marine systems (some evidence that they are new) Some of these

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







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



• 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



• 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


• 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.


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




• 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


• 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



Documents

Diseases and Conservation. Emerging Diseases New or “emerging” diseases are showing up in marine systems (some evidence that they are new) Some of these