Environmental Science ENSC 2800

1
Environmental Science ENSC 2800

• Spring 2003
• Class 9
• Bay-Delta Issue 3
• Endangered Species of the
• Bay Delta

2
Global Warming and Species Impacts

• Californias wildlife is at particular risk from
  the temperature and precipitation changes
  expected from global warming.
• Populations are reduced and fragmented in
  isolated and constrained genetic islands.
• By ecological standards, changes will be abrupt
  and the opportunities to migrate and shift ranges
  in line with moving niches is missing,
  particularly for woodland creatures.
• Invasive species are already prevalent in the CA
  ecology and many will gain increased competitive
  advantage over native species.

3
Biodiversity - broader context

• Biological diversity the variety of living
  things and their relationships to each other and
  interactions with the abiotic environment
• Genetic (DNA within a species e.g. saltmarsh
  harvest mouse)
• Species (No. different types of organisms in a
  given habitat e.g. a saltmarsh)
• Habitat/ecosystem (No. of different habitats or
  ecosystems in a particular region e.g.
  Bay-Delta).
• What is a species? Organisms that are similar
  enough genetically to produce viable offspring
  through reproduction.
• Different species live in communities, which
  together with the abiotic elements of a region
  make up a habitat.

4
Endangered Species Terms

• VULNERABLE - A species particularly at risk
  because of low or declining numbers or small
  range, but not a threatened species.
• THREATENED SPECIES a species whose population
  is not yet low enough to be in immediate danger
  of extinction, but which certainly faces serious
  problems.
• ENDANGERED SPECIES a species, plant or animal,
  that is in immediate danger of becoming extinct.
   
• EXTINCT SPECIES an extinct species is one that
  is no longer living, anywhere in its former
  range.
• EXTIRPATED SPECIES one that was formerly
  present in an area but has since disappeared from
  there (but still exists elsewhere).

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Causes of biodiversity loss

• According to the United Nations Environmental
  Programs Global Biodiversity Assessment, the
  four most important processes to date have been
• Land use change
• Over exploitation of species for human benefit
• Introduction of alien species to a region
• Pollution - both rapid and gradual forms (part of
  a concept known as biotic impoverishment)
• All these major factors are clearly at work in
  the Bay-Delta apply to California and are
  contributing to the reduction in the size,
  diversity and distribution of a range of species
  in the region.
• In the Bay-Delta we can add water resource
  over-exploitation as a major factor.

6
Forces for change

• The forces for environmental change interact to
  place pressure on species principally through the
  complex actions of food-webs and reproductive
  cycles.
• Species numbers decline due to a combination of
  increasing morbidity and mortality and lack of
  reproductive success.
• Although it is hard to separate out the impacts
  of each, the most important cause of species
  endangerment in the Bay-Delta is probably habitat
  loss and fragmentation due to land use conversion
  the 95 reduction in wetlands.
• Second place, because of the impact on water
  flows, riparian conditions, and groundwater
  levels, would probably be the damming and
  diversion of water.
• Third and fourth place would probably be the
  introduction of invasive species predators and
  competitors and pollution.

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California Biodiversity

• According to an extensive inventory developed by
  Jones and Stokes (1987)
• California is home to 748 species of vertebrate
  animals.
• More than 550 species of birds have been recorded
  in the State.
• Some 5,200 species of native plants grow within
  California.
• About 40 of the freshwater fish, 30 of
  amphibians and 10 of mammals are endemic.
• Roughly 1/3 of California plants do not occur
  outside the state.
• There are judged to be around 380 distinct types
  of natural assemblages of plants and animals (we
  can call these habitats although the exact
  definition is often hard to pin down).
• If the total plants and animals are thus around
  6,500, some 5 are legally classed as either
  threatened or endangered.
• CA is second only to Hawaii in officially TE
  species.

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Endangered Species Legislation

• The California Endangered Species Act of 1970
  (CESA) parallels the main provisions of the
  Federal ESA (1973) and is administered by the CA
  Dept. of Fish and Game.
• Under CESA the term "endangered species" is
  defined as a species of plant, fish, or wildlife
  which is "in serious danger of becoming extinct
  throughout all, or a significant portion of its
  range" and is limited to species or subspecies
  native to California.
• CESA establishes a petitioning process for the
  listing of threatened or endangered species.
• CESA prohibits the "taking" of listed species and
  applies to candidate species also (those being
  considered for listing).
• State law defines "take" as "hunt, pursue, catch,
  capture, or kill, or attempt to hunt, pursue,
  catch, capture, or kill.
• Species also found in other states may not be
  protected under CESA but nevertheless have
  federal protection under ESA.

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Playing God

• The CA DFG is permitted to allow ES, TS or CS
  populations to be adversely affected (but not
  driven to extinction) if specific economic,
  social or other conditions make proposed
  alternatives infeasible these are called
  incidental takings.
• The same is true at the Federal level where the
  ESA created the so-called God-Squad (ES
  committee) which decides, using cost-benefit
  concepts, whether a species should be allowed to
  be adversely affected by projects with federal
  oversight.
• DFG must thus recommend reasonable and prudent
  measures to conserve the species to prevent any
  direct jeopardy or minimize the adverse impacts
  of the incidental jeopardy.

10
Biodiversity recovery plans

• Recovery is the process by which the decline in
  an endangered or threatened species is arrested
  or reversed and threats to its survival are
  neutralized so that its long-term survival in
  nature is ensured (US FWS 1995).
• The goal of the process is the maintenance of
  secure,self-sustaining wild populations with
  minimum necessary investment of resources.
• A recovery plan delineates, justifies, and
  schedules the research and management actions
  necessary to support recovery of a species.
• When habitat has been drastically altered,
  recovery may be a very difficult and costly
  proposition.

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Biodiversity in the Bay-Delta

• The Status and Trends Report for Wildlife of the
  San Francisco Bay Estuary (SFEP 1992) lists over
  380 terrestrial vertebrates amphibians,
  reptiles, birds and mammals associated with the
  Bay in the counties immediately adjacent to the
  Bay and Delta.
• At least 10 vertebrates have been extirpated from
  the region,including sea otters, pronghorn
  antelope, elk and California condors. Two
  species, the grizzly bear and grey wolf, have
  been eliminated from the entire state (SFEP
  2000).
• Some 52 different native fish species exist in
  the Bay-Delta, some 25 in the freshwater creeks
  and streams draining into the Bay-Delta.
• As of the last big survey (1992), SFEP listed 150
  wildlife, insect and plant species as being of
  special status, extirpated or extinct in the San
  Francisco Estuary area. Some 90 of these are
  listed at the Federal /or State level as of
  concern, candidate, threatened or endangered.
• Statewide, lists of endangered species can be
  viewed at the DFG web site. For a gallery of
  important Bay-Delta Species, click Here.

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Anadromous Fishes

• Chinook Salmon
• Oncorynchus tshawytscha The winter-run chinook is
  listed as Endangered by both the State of
  California and the Federal Government
• See http//www.delta.dfg.ca.gov/gallery/chin.html

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Anadromous fishes

• The Bay-Delta is both a lifeline and a bottleneck
  in the life-cycle of the Central Valleys
  anadromous fishes, especially the Chinook salmon.
• Central Valley salmon occur in four discrete runs
  winter-run, spring-run, fall-run and late
  fall-run (run refers to the season in which
  adults return to their native streams to spawn
  SFEP-2000).
• The winter-run Chinook,with the lowest
  population, has been listed as both a state and
  federal endangered species since 1994 (down to an
  historic low of 841 in 1997).
• The next most sensitive stock, the spring-run,was
  state listed as a threatened species in 1998 and
  federally listed in 1999 (a five-year low of
  5,312 was recorded in 1997).
• The fall-run are the most abundant, with 308,674
  returning in 1999 to the Sacramento and 24,459 to
  the San Joaquin.
• Back before the Gold Rush, one to two million
  salmon would swim through the Delta on their way
  to spawn each year.

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Restoring migrating fishes

• No single restoration and protection measure will
  work since the fish are vulnerable at all of
  their life cycle stages, for different reasons.
• Effort needs to be addressed at helping adults
  navigate the Delta (creating appropriate flow
  conditions, water quality, and prevention of
  entrainment in pumps).
• Adults need help in surviving the swim upstream
  to spawning grounds (reducing predators, limiting
  fishing and bypassing obstacles).
• Successful reproduction requires that there are
  appropriate conditions for spawning, egg hatching
  and fry survival (good substrate conditions,
  adequate refugia and good water quality).
• Finally, juveniles (smolts) require the same
  treatment as their parents to allow their
  successful return back to the ocean, plus they
  need to survive the next three years or so (a
  little luck and some appropriate limits on
  commercial/sport fishing!).

15
Saltmarsh Harvest Mouse

• Reithrodontomys raviventris
• State Status Endangered, 1971
• Federal Status Endangered, 1970
• It inhabits tidal and nontidal salt marshes of
  Suisun, San Pablo, and central and south San
  Francisco bays.

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Saltmarsh Harvest Mouse

• A federally and state listed endangered endemic
  species of which less than 2,000 are thought to
  remain in the saltmarshes bordering the San
  Francisco Bay.
• One of the more unique mammals because it can
  drink salt water and eat plants that are
  halophytic (can live in saltwater and salty
  soils).
• Over 80 of its original habitat is gone and the
  remaining 20 is at risk from development or
  changes such as cordgrass invasion that will
  cause the saltmarsh vegetation to die out.
• Recovery requires protection and selective
  replacement of this ecosystem around the Bay
• Of particular importance for survival is also the
  preservation and enhancement of adjacent riparian
  high tide escape zones and ecotonal buffer areas
  to offer refugia in floods and to prevent
  predation by foxes, feral cats, etc (we are
  realizing this for other species too e.g.
  Red-legged frogs in the freshwater marshes).
• Simply putting a line around the pickleweed
  marshes and assuming that the mouse will be
  protected has proven ecologically insufficient.

17
California Red-Legged Frog

• Rana aurora draytonii
• State Status Species of Special Concern
• Federal Status Threatened, 1996
• Significant numbers of California red-legged
  frogs occur only in the relatively small coastal
  drainages between Point Reyes (Marin County) and
  Santa Barbara (Santa Barbara County).

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California Red-legged Frog

• Made famous by Mark Twain and a favorite gourmet
  food item at the turn of the 19th/20th century.
• Breeds in permanent water but migrates up to
  several miles between riparian woodlands over
  intervening terrain.
• Reductions in wetlands reducing breeding grounds
  and reproductive success and fragmentation of
  habitat with land uses that lead to high
  mortality between breeding seasons have severely
  impacted population levels.
• Other factors include pollution, 50 different
  invasive predators (e.g. mosquito fish,
  bullfrogs), modified water flows, impacts of
  cattle and proliferation of non-native
  vegetation.
• Listed as Federal ES in 1996 and some 5 m acres
  in California were dedicated critical habitat
  and subject to environmental review less than
  25 of its historical range.
• Subject to restoration efforts, principally
  through habitat restoration (wetlands, water
  conditions salinity, depth and temp., predator
  removal, creation of dense veg. and corridors,
  etc.) and reintroduction.

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Readings From Merchant

• To compliment these classes on biodiversity
  issues, please read the short essays and articles
  in Merchant beginning on pages 125, 162, 185,
  189, 194, 227, 287, 293, 312, 406, 423.