Lecture 7: Extreme Environments

• Within and around all regions are extreme environments with some habitats spanning large areas and some highly fragmented

  • Diversity is a combination of ability to adapt to environment
  • Function of phylogeny and Biology (pre-adapted)
  • Opportunity to disperse into environment
  • Function of geography

  Large Areas/Continuous Environments (Open Ocean)

  • Epipelagic Open Ocean
  • Deep Sea (Meso, Baso, Abysal)

  Fragmented/Disjunct Environments

  • Vents/Seeps
  • Desert
  • Torrents (Mountains)
  • Areas where water is dropping rapidly in elevation
  • Caves

  
• Discuss biodiversity in the Epipelagic?

  Upper 200 m off the continental shelf

  Light varies from full sunlight to complete darkness

  Pressure varies w/ weather and wave action

  • The deeper the water the more pressure with changes being especially notable

  Temperature varies w/ season and greater time scales

  Nutrients vary w/ season and greater time scales

  • Productivity especially related to the ocean conveyor
  • Geographic variance as well

  
• Using this image where are the notable sites for nutrient upwelling? Are there any other important features to note?

  Polar Waters

  • Near Upper North America & Upper Europe

  Indian Ocean

  • Near South East Asia

  Pacific Ocean

  • Near North America, particularly Alaska

  The denser the water the closer it is to the bottom

  • South Atlantic Central Water
  • Makes the circumpolar water mass
  • Antartic Intermediate Water
  • North Atlantic Deep and Bottom Water
  • Antartic Bottom Water

  
• Using this image what is an important note about the oceanic currents?

  Water reflects away from the equator

  
• Describe Ekman Transport and Geostropic Flow?

  Ekman Transport: The net movement of water caused by the combination of wind and the Coriolis effect, resulting in a 90-degree deflection of surface currents. Geostrophic Flow: A balance between the pressure gradient force and the Coriolis effect, resulting in horizontal winds or ocean currents that flow parallel to isobars or contour lines. Useful in upwelling

  
• How do epipelagic species deal with the variation in nutrient upwelling in their habitat?

  Boom and Bust

  • When conditions are good (La Nina) populations have exponental growth. When conditions are bad (El Nino) populations have exponential decline
  • Herrings
  • Achovies
  • Silversides

  Migratory

  • Tunas
  • Billfishes
  • Mackerel Sharks
  • Jacks
• Why is epipelagic diversity low? Is it random?

  About 325 species

  1. Lack of barriers
  2. No physical barriers
  3. Broad uniformity
  4. High tolerance for changing conditions make barriers easily passable
  5. Biological constraints
  6. Highly mobile
  7. Body Shape similar for buoyancy control
  8. Muscle arrangement for constant movement
  9. Open Environment
  10. Sensory modality bc lack of microhabitats
  11. Coloration to avoid predators and capture prey

  Diversity not random with respect to taxon

  • 73% of Lamniformes
  • Other sharks, 10 species
  • Most scombrid fishes (abt 50 sp.) & all billfishes + swordfishes fishes

  
• Discuss mesopelagic diversity?

  Below the epipelagic so changing pressure is most notable

  • 200 m - 1000 m
  • Temporally stable but dynamic by depth

  Twilight zone

  • Downwelling light to 1,300 m
  • No photosynthesis = no primary production

  Nutrients from above

  • Some use diel vertical migration to use epipelagic production
  • lanternfishes & hatchetfishes
  • > 500 m -> surface

  Permanent thermocline that rapidly changes from surface conditions to constant deep sea temperature

  Change in faunal composition as temperature decreases w/ depth distrib location dependent

  • ex. depressed in tropics

  
• Discuss what diversity is found in the Mesopelagic?

  Elopomorpha

  • Spiny eels
  • Snipe eels

  Protacanthopterygii (Argentiniformes)

  • Barreleyes
  • Slickheads

  Stenopterygii (Stomiiformes)

  • Bristlemouths
  • Dragonfishes
  • Lightfishes

  Cyclosquamata (Aulopiformes)

  • Lancetfishes
  • Telescope fishes

  Scopelomorpha (Myctophiformes)

  • Lanternfishes

  Lampriformes

  • Tube-eyes

  Acanthopterygii

  • Tapertails

  Perciformes

  • Swallowers
  • snake mackerels

  
• Discuss Benthal Diversity?

  200 m to 1000 m

  Over 1000 sp and 50 fam

  • Hagfishes
  • Squaliformes
  • Lantern sharks
  • Gulper sharks
  • Carcharhiniformes
  • Catsharks
  • Rajiformes
  • Skates
  • Chimaeriformes
  • Shortnose chimearas
  • Longnose chimeara
  • Elopomorpha
  • Halosaurs
  • Cyclosquamata (Aulopiformes)
  • Lizardfishes
  • Tripodfishes
  • Paracanthopterygii
  • Grenadiers
  • Cusk-eels
  • Batfishes
  • Acanthopterygii
  • Snailfishes
  • Perciformes
  • Eel-pouts
  • Boarfishes

  
• Is benthal diversity random with respect to taxa?

  Diversity not random with respect to taxon

  • Older taxon more dominant because they had more time to adapt and colonize

  Elasmobranchs

  • Rajidae (>210 sp)
  • Scyliorhinidae (>100 sp)
  • Squaliformes (7 fam, >100 sp)

  Basal Teleosts

  • Stomiiformes (all 5 fam)
  • Aulopiformes (11 fam of 15)
  • Myctophiformes (2 fam but ~ 250 sp)
  • Ophidiiformes (3 fam of 5)
  • Deeper water = more basal teleosts

  Only 7 Percomorph Families

  • Stephanoberyciformes (1 fam out of 9)
  • Scorpaeniformes (1 fam out of 26)
  • Perciformes (5 fam out of 160)

  
• Discuss bathypelagic Diversity?

  1000m to 4000 m

  Fairly temporally stable and stable by depth

  • Small relative pressure change

  Complete darkness

  • Except for bioluminescence
  • No photosynthesis = no primary production

  Nutrients come from above

  • little organic material
  • Eat or be eaten
  • Scavenging important (bathal)

  Below thermocline water varies from ~5-3 degrees from top to bottom

  Low Diversity (less than 200 sp and 15 fam)

  
• Discuss the species and families that live in the Bathypelagic zone?

  Elopomorpha

  • Spiny eels
  • Sawtooth eels
  • Gullpers
  • Inflatable, highly evolved to thrive here
  • Pelican eels
  • Inflatable, highly evolved to thrive here

  Protacanthopterygii (Argentiniformes)

  • Slickheads

  Stenopterygii (Stomiiformes)

  • Bristlemouths

  Paracanthopterygii

  • Pelagic cods
  • Grenadiers
  • Cusk-eels
  • Ceratioid Anglerfish

  Acanthopterygii

  • Bigscale fishes
  • Whalefishes
  • Fangtooths

  Perciformes

  • Swallowers
• Discuss benthal diversity of the bathyal zone?

  This region is where constrains on how low cartilaginous fishes can go starts showing up

  • 3000 meters

  Squaliformes

  • Gulper sharks
  • Lantern sharks
  • down to ~4500 m

  Carcharhiniformes

  • Catsharks

  Rajiformes

  • Skates
  • down to ~ 4500 m

  Chimaeriformes

  • Shortnose chimearas
  • Longnose chimearas

  Cyclosquamata (Aulopiformes)

  • Tripodfishes
  • down to 6000 m

  Paracanthopterygii

  • Grenadiers
  • down to ~4000 m
  • Cusk-eels
  • down to ~8000 m
  • Merlucid hakes
  • down to ~4000 m

  Acanthopterygii

  • Snailfishes
  • down to 8000 m
• Is the diversity of the bathyal zone random with respect to taxon?

  Diversity not random with respect to taxon

  Two groups show great diversity

  • Ceratioid Anglerfish
  • All 11 fam with > 100 sp
  • Highly specialized
  • Bioluminescence, Extreme Sexual Dimorphism, Bathypelagic lifestyle
  • Adaptive radiation about 100 mya
  • Cetomimoidea (whalefishes)
  • 3 of 6 fam > 25 sp

  Other families only present in this area but not specious

  • Fangtooths (Both sp)
  • Pelagic cods (Both sp)

  Only 10 percomorph families represented

  • Scorpaeniformes (1 out of 26 fam)
  • Perciformes (3 out of 160 fam)

  
• Why are early teleosts better represented in the bathyl zone?

  Early teleosts had more time to invade the depth and evolve. As new species evolved over time these deep sea habitats were not as avaliable as they were before
• Discuss challenges to benthal fishes?

  Communities surround vents or seeps

  • Energy produced through chemosynthesis
  • Food web not tied to photic zone

  Areas near may be challenging

  • Low dissolved oxygen
  • High levels of hydrocarbons
  • Close to source, animal must be well adapted
  • Families include
  • Eel-pouts
  • Cusk-eels
  • Grenadiers

  Ephemeral communities also present at whale-falls

  • Food web temporarily released from photic zone
  • First by energy consumed from carcass
  • Second by ephemeral chemosynthetic community
  • Fishes will be representative of local diversity

  
• Discuss challenges to Desert Fishes?

  Definition: Areas where water is severely limiting

  • Year round
  • Seasonally (Monsoon Seasons)

  For fishes water limitation means:

  • Small amount of available habitat
  • Extreme variation in:
  • Temperature
  • Cold when rainy but not when dry
  • Alkalinity
  • V fresh but as evaporation happens this changes
  • Salinity
  • Dissolved oxygen
  • Hot, stagnent water = low O2

  Three main ways to deal with variation

  • Short life span and egg diapause
  • Diapause = Acanthopterigii & series Atherinomorpha
  • Secondary respiratory structures
  • Estivation (Lungfish only)

  
• What are some fish that live in desert environments?

  Acanthopterygii

  • Series Atherinomorpha
  • Two large triangular hypural plates
  • Premaxilla does not directly articulate with maxilla
  • Four pectoral actinosts (cuboidal)
  • Reproductive biology
  • Diapause (delayed hatching)
  • Morphology of testes, sperm bundling
  • Demersal eggs with sticky filaments

  Cyprinodontiformes

  • From a group of marine fishes
  • High salinity tolerance
  • Egg diapause
  • Rivulines
  • Found in Old World and New World

  Desserts of U.S. southwest

  • Pupfish
  • Goodieds
  • Livebearers

  
• Diapause is able to occur due to moisture underneath the soil keeping the eggs moist. Eggs in diapause can last for months but not years

  
• Describe features that increase fish survival in a Desert?

  Air Breathing through Modified Gills

  • Thick, widely spaced lamellae
  • Thin= stick
  • Branched, bulbous dendritic structures on 2nd and 4th gill arches
  • Help support gills in air
  • Ex. Walking Catfish
  • Asia & Africa
  • Epibranchial organ
  • Walk with pectorals
  • Burrows in mud

  Lungs

  • Lungfish & Bichirs
  • Obligate air breathers
  • Adapted to extreme droughts
  • Heavily vascularized lungs
  • Vestigial gills for CO2 exchange

  Estivate

  • South American & African Lungfish
  • Salamanderfish
• Describe the differences between Lungfish and Salamanderfish estivation?

  African Lungfish & South American Lungfish

  • Have lungs
  • Also will burrow into mud
  • Form a mucous cocoon
  • Estivation may last years

  Salamanderfish

  • Live in small often ephemeral pools
  • May burrow into sediment
  • Estivation periods relatively short (Weeks, maybe months)

  
• Describe the challenges living in torrent zones?

  Areas of very high flow

  Water descending from elevation

  Conserved morphology:

  • Flattened body
  • Large, low pectoral fins
  • Presence of sucker on
  • Mouth
  • Pelvic fins
  • Also fin spines to jam oneself in place
  • Lack of swim bladder
  • Downturned mouth
  • Modified respiratory structure/behavior
  • Super high oxygen levels require this

  
• Pt. 1 Is diversity random with respect to taxa in torrent zones?

  No

  Many Siluriform fam (~6)

  • Torrent catfishes
  • South East Asia, Japan, India
  • Mountain catfish
  • Chile
  • Climbing catfishes
  • South America (Andes)

  Catfish may be “pre-adapted to environment”

  • Flattened
  • Downturned mouths
  • Low pectoral fins
  • Spines to stick in place

  Many cypriniforms (~4)

  • Hillstream loaches
  • Asia
  • Mountain carp
  • South East Asia
  • Algae eaters
  • South East Asia

  2 ostariophysan fam

  • Knerias
  • Africa
  • Parodontids
  • South America, Panama

  
• Pt. 2 Is diversity random with respect to taxa in torrent zones? Cont.

  Perciform families secondary freshwater or diadromous (~4)

  • Are located in areas where niche is “open” Islands, remote regions
  • Islands/coast in habitats that recently evolved in geological time
  • Clingfishes
  • Central and northern South America
  • Gobies
  • South East Asia, Indo-Pacific
  • Loach gobies
  • China, New Zealand, Indonesia, Solomon Islands
  • New Zealand torrent fish
  • New Zealand

  Gobies and clingfishes had suction cup prior to invasion
• Discuss needed traits for diversity within caves?

  Hypogean fishes (troglobites)

  • Partial or total darkness
  • Low productivity
  • Conditions relatively constant

  Conserved morphology:

  • Loss of eyes
  • Loss of pigmentation
  • Reduced squamation
  • Less scales = more free neuromasts
  • Free neuromasts
  • Increased chemosensory functioning

  
• Discuss diversity in cave fish?

  Diversity spread across 10 ord (19, fam >135 sp)

  • Cave forms may be populations or species
  • Cave = troglobite form; surface = normal

  A high number of siluriforms

  • Walking catfishes
  • Asia, Africa
  • North American catfishes
  • North America
  • Pencil catfishes
  • South America (Andes)

  Other ostariophysans

  • Tetras
  • Minnows
  • Loaches
  • Glass knifefishes

  Most other taxa are single fams in order

  • Percopsidormes (Cavefishes)
  • Cyprinodontiformes (Livebearers)
  • Scorpaeniformes (Sculpins)
  • Synbranchiformes (Swamp Eels)
  • Perciformes (Gobies & Sleepers)

  
• Discuss notable features about cave forms?

  High lv endemism

  • 48 species known only from type locality
  • Conservation concern

  Family Amblyopsidae

  • Found only in eastern, southeastern U.S
  • Primarily cave dwellers
  • 5 of 6 species found in cave
  • 4 of 6 have lost eyes