1. BENTHOS

2. BENTHOS: DEFINITIONS
Epifauna: live on or are associated with the benthic surface
Infauna: live within the substrate
Microfauna: animals <0.1 mm in size (e.g. protozoa/bacteria)
Meiofauna: animals <0.5 mm in size: “interstitial” (e.g. nematodes, sm. amphipods)
Macrofauna: animals > 0.5 mm in size: most familiar kinds of animals (crabs, shrimp, starfish and most mollusks)

3. Abiotic Factors Affecting Benthos (to 200 m depth))
Wave action: influence distribution of sediments and physically affect animals
Sediments: vary according to wave action (particle size sorting): terrigenous and marine origin (“allochthonous” and “autochthonous”): fine clays go to deeps
Salinity and temperature: FW influences; more thermal variability

4. Distribution and biomass of benthos

5. The Intertidal: Where the Benthos is Most Abundant
Biomass in intertidal= 10X that of 200 m depth and several thousand that of abyss!
Not without a cost: wave shock; desiccation; cold; osmotic issues; and land predators. But at high tide: plenty of O2; nutrients; light; and wastes washed away.
More relief and habitat diversity= more species diversity

6. Reproduction and Dispersal
Broadcast spawning vs. brooding- varying amounts of energy invested, and value of dispersal
Where to settle? 1) chemical attractants: settle near your own kind 2) bottom types: settle in appropriate substrates

7. PATTERNS OF DIVERSITY WITH DEPTH

8. Where the food comes from

9. Effects of predator exclusion on the abundance of macrofaunal molluscs, worm and crustaceans
General results:
cages have up to 500 x density
more infaunal spp. in cages
no dominance by any single species

10. Soft Sediment Communities
Types of soft-bottom habitats
Role of disturbance in regulating community structure
Effects of predation, competition and facilitation

11. Submarine canyons
Latitudinal Diffs.
Temp. = sand
Tropic. = mud
Polar. = Gravel (Arctic w/ riverine mud)
Shallow water/Shelf
Deep seafloor

12. Sandy shores/beaches

13. Muddy shores/bays, estuaries, and lagoons

14. Nearshore benthic habitats (0-200 m)

15. Meiofauna (few mm) Benthic diatoms Harpacticoid copepods
Foraminiferans

16. Macrofauna (mm-cm)
polychaete worms
crustaceans

17. Macrofauna (mm-cm)
heart urchins
pycnogonids
brittle stars
bivalves

18. High biodiversity that varies with depth, sediment type and biotic factors

19. Infaunal community “Patchiness” is the rule
1. Biotic interactions: predation, competition, & facilitation
2. Physical factors: disturbance (biotic, physical, and anthropogenic)

20. Community patterns and structure
Temperate/tropical
Polar

21. Megafauna (cm-m) grey whales
walrus
Predators have a big effect on community composition

23. Caging Studies

24. Direct and indirect effects of predation in soft-sediment food webs

25. Important classification for understanding effects of disturbance
Life-history groups
Capitella captitata
Succession

26. BIOTURBATION Upogebia- another burrowing shrimp Upogebia BURROW
fecal strands
from polychaetes
Burrows of Callianassa
BURROWING SHRIMP
Callianassa

27. MORE BIOTURBATORS Harpacticoid copepod Burrowing holothurian
Polychaete: Nereis
Oligochaete: Paranais

28. The lugworm (Arenicola) and its burrow/fecal castings28

29. Gastropod: Hydrobia
Gastropod 2: Ilyanassa 29

30. Sediment modifiers
Ammensalism/mutualism
Facilitation

31. Competition can be important in soft-sediment communities
Competition in a 3-d environment: rarely for space
Competition usually for food with big effects on growth, reproduction, and survival. Density-dependence common
Competition has a big effect on community structure- depth distribution, population distribution, abundance, and dynamics

32. The intermediate disturbance
hypothesis

33. Would you expect the intermediate disturbance hypothesis to explain diversity patterns in soft sediments?

34. Types and scales of disturbances
in soft-sediments

35. Disturbance caused by eutrophication

36. Iceberg scour disturbance

37. On frequently scoured seafloor, what functional groups would you expect?

39. Re-colonization Different mechanisms: Vegetative regrowth of survivors
Recruitment from propagules (including spore and seed bank)
Influence of patch characteristics:
Size and shape
Substrate characteristics (e.g. rock or sediment types, topographic complexity, biogenic structures)
Patch location (environmental conditions and proximity to propagule sources)
Timing of patch creation (availability of propagules and differences in conditions)

40. PHYSICAL DISTURBANCES
Agent of disturbance
Waves and currents
Water-borne material
(sediment, logs, rocks)
Ice
Direct impacts on
organisms and
Substrate
Sessile organisms
detached or broken
Mobile animals displaced,
injured, or killed
Substrate overturned
Sediment eroded
Organisms abraded, buried,
crushed or detached
Organisms abraded, detached
Sediment and organisms
excavated and displaced
Habitat or
assemblages
effected
Most, declines with depth
Most
Rocky intertidal and subtidal,
Soft sediment, Seagrass beds,
Salt mashes (high lat)

41. PHYSICAL DISTURBANCES
Agent of disturbance
Extended aerial exposure
Temperature extremes
Salinity stress and
freshwater flooding
Anoxia
Direct impacts on
organisms and
Substrate
Organisms injured or killed
by desiccation, heat, UV
by heat or cold. Bleaching
by osmotic stress
by metabolic stress
Habitat or
assemblages
effected
Rocky intertidal
Coral reefs
Seagrass beds
Tide pools, Kelp forests, Coral reefs
Rocky intertidal,
Salt marsh, Coral reef, Mangrove,
Soft sediment
Soft sediment, estuaries, semienclosed seas

42. PHYSICAL DISTURBANCES
Agent of disturbance
Landslides, tectonic events
Lava flow, volcanic ash
Fire, lightening strikes,
Meteorite impacts
Direct impacts on
organisms and
Substrate
Organisms abraded, crushed,
displaced, or smothered
Organisms injured or killed
by lava, smothered by ash
by heat
Direct impact and
climate change
Habitat or
assemblages
effected
Rocky intertidal
and subtidal,
Soft sediment, slope and rise,vents
Rocky intertidal and subtidal, Seagrass beds, Coral reefs, vents
Salt marsh, Mangrove
Global (mass extinctions)

43. BIOLOGICAL DISTURBANCES
Agent of disturbance
Accumulation of plant
or animal material
(wrack and carcasses)
Algal whiplash
Bioturbation
Sediment excavation by
predators
Direct impacts on
organisms and
Substrate
Organisms smothered, buried
and shaded, chemistry
Organisms abraded,
recruits vulnerable
Organisms buried, sediment
load interferes with feeding
Organisms displaced,
uprooted, and buried
Accumulation of debris
Habitat or
assemblages
effected
Salt marsh, Seagrass beds,
Soft sediment
Rocky intertidal and subtidal
Soft sediment, Seagrass beds
Soft sediments
Seagrass beds

44. BIOLOGICAL DISTURBANCES
Agent of disturbance
Haul out, trampling
Red tide
Direct impacts on
organisms and
Substrate
Organisms smothered, buried,
smashed
Organisms suffocated and
poisoned
Habitat or
assemblages
effected
Rocky intertidal
Soft sediment, coastal environments

46. Anthropogenic disturbances in soft sediment habitats
Oil spills

49. 14 years of intensive study
Exxon-Valdez oil spill
Bleigh Reef in NPWS
42 million L of oil
1990 km of coastline and
750 km southward
14 years of intensive study
Ecosystem level impacts
Prince William Sound, AK on 24 March 1989

52. Ecological impacts of the EVOS
New understanding of long-term effects and recovery processes. Ecosystem-based toxicology
Before: short-term impact assessments and lab studies of toxic effects
First real ecosystem impact study
General conclusions:
1) Oil persisted beyond a decade in surprising amounts and toxic forms because of the presence of soft-sediments
2) Oil significantly bioavailable to induce chronic biological exposure
3) Longterm effects at population level

53. Ecological impacts of the EVOS
3 major pathways of exposure & induction:
Acute exposure to oil during spill and subsequent negative health effects
Chronic persistence of oil, bio-exposure, and population impacts to species closely associated with shallow sediments
Indirect effects related to predator-prey relationships, loss of habitat

54. Acute effects of spill Oil in fur, feathers, and ingested
sea otters
~250,000 seabirds
302 harbor seals
Oil in fur, feathers, and ingested
Mass mortality of macroalgae, benthic invertebrates
on shore from a combination toxicity, smothering, and
physical displacement caused by high pressure clean-up

55. Persistence of oil
40-45% oil grounded in 1989 on 787 km of PWS beaches
7-11% contaminated 1203 km of Gulf of AK coastline
2% remained on beaches after 3.5 yrs (-0.87 per yr)
Rates of dispersion and degradation diminished through time
Suppressed by physical barriers to disturbance, oxygenation
and photolysis
Oil trapped in sediments and mussel beds

56. Effects of chronic exposure
Chronic exposure of sediment affiliated species
Fish embryos exposed to partially weathered oil
Multi-ringed PAHs toxic to pink salmon eggs at 1 ppb when
exposed for months
Toxic to herring eggs when exposed for 16 days
Reduced salmon and herring reproduction in many areas

57. Led to death from compromised health, growth, or reproduction
Effects of chronic exposure
Lower growth rates of salmon = reduced survival
Abnormal growth in herring and salmon caused by endocrine disruptors = less fat
Led to death from compromised health, growth, or reproduction

58. Cascades of indirect effects
Trophic cascades in which predators reduce abundance
of their prey which releases the preys food species from
control
Provision of biogenic habitat by organisms that serve
as or creates important physical structure in environment
Two most important types of cascades
Current Risk Assessment models used for projecting biological injury to marine communities ignore indirect effects

63. Four groups of dominant macrofauna in soft bottoms
Class Polychaeta: most numerous: tube-building and burrowing
Subphylum Crustacea: ostracods, amphipods, isopods, tanaids, mysids, small decapods
Phylum Mollusca: burrowing bivalves and scaphopods, gastropods at surface
Phylum Echinodermata: brittle stars, heart urchins, sand dollars, sea cukes

64. Soft- and hard-bottom benthic communities
Soft: little ‘relief’: ripple marks, worm tubes, fecal mounds: some differences in sediment grain size: fewer inds. And infauna and more epifauna in sand: more individuals in mud and most are deposit feeders
Hard: more ‘relief” and more habitat diversity: increase in suspension feeders

65. Feeding strategies
Deposit feeders: feed on organically enriched sediments: continuous “reworking” of sediments to extract nutrients: analogous to earthworms: can live in very fine sediments
Suspension feeders: filtering devices or mucus nets collect detritus or plankton: need coarser sediments or hard bottom
Grazers/predators/scavengers

66. Deposit Feeders

67. Suspension feeders Bryozoan Hydroid Sponge Bivalve Polychaete Tunicate
Barnacle
Amphipod
Anemone
Brittlestar

68. PARALLEL BOTTOM COMMUNITIES

69. FUNCTIONAL GROUPS
(or: bioturbators)

70. FEEDING IN AN INFAUNAL CUCUMBER

71. PREDATORS OF BENTHOS

72. CAGE STUDIES

73. COMPETITION FOR SPACE

74. LIFE IN THE MUDS: A COMPLEX SITUATION

75. COMMUNITY CHANGES: STORM INDUCED

76. SEASONAL POPULATION CHANGE

77. LONGER-TERM OSCILLATIONS IN ANOTHER AMPHIPOD

78. Biomass of benthos in relation to distance from coast and depth

79. RECOVERY OF BENTHIC COMMUNITY
FOLLOWING
DEFAUNATION BY RED TIDE