Benthos. Mats Westerbom презентация

Mats Westerbom
Benthos
Benthos is the community of organisms that live on, in, or near the benthic zone (seabed or seafloor).
From Ancient Greek βένθος (bénthos, “the depths”).

BENTHOS
Substratum
Size
Feeding
Type
Soft sediments
Rocky
Macro
(>0.5 mm)
Meio
(0.1-0.5 mm)
Micro (<0.1mm)
Filter
Deposit
Zoo
(benthos)
Phyto
(benthos)
Habitat/Site
Infauna
Epifauna

ZOOBENTHOS
PHYTOBENTHOS
Microphytobenthos (benthic microalgae)
Marine macroalgae
Macrozoobenthos
Meiozoobenthos

BENTHOS
Substratum
Size
Feeding
Type
Soft sediments
Rocky
Macro
(>0.5 mm)
Meio
(0.1-0.5 mm)
Micro (<0.1mm)
Filter
Deposit
Zoo
(benthos)
Phyto
(benthos)
Habitat/Site
Infauna
Epifauna

Benthic fauna (invertebrates): How big are you?
Three different size classes:
1. Macrobenthos / Macrofauna > 0.5 mm (but also > 1 mm)
Polychaetes (Polychaeta)
Snails (Gastropoda)
Amphipods (Amphipoda)
Hydrobia acuta
Eunice pennata
Fredrik Pleijel.
Gammarellus angulosus

Benthic fauna (invertebrates): How big are you?
Three different size classes:
2. Meiofauna / Meiobenthos 0.1 – 0.5 mm
“Temporary meiofauna e.g., juvenile/larvae stages of macrofauna eg. Polychaetes”
Ostracoda
Foraminifera
Nematodes
© Peter Serov

Benthic fauna (invertebrates): How big are you?
Three different size classes:
3. Microfauna / microbenthos < 0.1 mm
Protists and bacteria
Euglena sp.

BENTHOS
Substratum
Size
Feeding
Type
Soft sediments
Rocky
Macro
(>0.5 mm)
Meio
(0.1-0.5 mm)
Micro (<0.1mm)
Filter
Deposit
Zoo
(benthos)
Phyto
(benthos)
Habitat/Site
Infauna
Epifauna

What do you (benthic invertebrate fauna) feed?
Detritivores:
Herbivores:
Carnivores/ predators:
feed on plant material
feed on live individuals of various sizes
feeds on detritus (breaks down dead plant or animal matter)
Sea urchin (Paracentrotus lividus)
Saduria entomon

How do you feed?
Suspension feeders
Feed on the plankton above
They have special structures designed to capture and concentrate particulate matter and phytoplankton.
They dominate areas where turbulence is greater and the substrate is composed of larger sand grains.
(e.g., bivalves, ophiuroids, crinoids),
Filter-feeders find their food in much the same way as suspension-feeders: the only difference is that they themselves create water currents towards the special food retention appendages by means of siphons or articulated appendages.

How do you feed?
Deposit feeders
Eat organic material in sediments
They burrow below the surface and extract food from large amounts of sediment.
Turbulence is low and the substrate consists of fine, silt particles and detritus (dead organic mater).
(e.g., holothurians, echinoids, gastropods),
Marenzelleria viridis

An illustration of the two ways of feeding by the Baltic clam, Macoma balthica (© Anna Törnroos)
Baltic clam Macoma balthica

BENTHOS
Substratum
Size
Feeding
Type
Soft sediments
Rocky
Macro
(>0.5 mm)
Meio
(0.1-0.5 mm)
Micro (<0.1mm)
Filter
Deposit
Zoo
(benthos)
Phyto
(benthos)
Habitat/Site
Infauna
Epifauna

The major part of the benthic fauna is buried in the sediments and is, thus, called “infauna“
Profile of the sea floor showing typical infaunal/epifauna organisms (from Pierre Tardent).
Barnacles (Balaniden)
Blue mussels (Mytilus edulis)
Polychaete Lanice conchilega,
Polychaete Lagis koreni,
Snail Littorina littorea,
Rasor clam (Ensis americanus),
Bivalve Cerastoderma edule,
Bivalve Scrobicularia plana,
Bivalve Mya arenaria
k) Polychaet Arenicola marina,
l) Polychaete Hediste diversicolor,
m) Bivalve Macoma balthica

BENTHOS
Substratum
Size
Feeding
Type
Soft sediments
Rocky
Macro
(>0.5 mm)
Meio
(0.1-0.5 mm)
Micro (<0.1mm)
Filter
Deposit
Zoo
(benthos)
Phyto
(benthos)
Habitat/Site
Infauna
Epifauna

Soft bottoms
Rocky bottoms
M. Westerbom
M. Westerbom
Environmental (abiotic) facors affecting life:

Soft sediments

http://faculty.chemeketa.edu/afrank1/rocks/sedimentary/sedtexture.htm

Finland 2016

Storfjärden
”Mud”, which can be anything (from silt to clay and everything mixed with organic matter)
Fine-grained soft bottom, with a high % of organic material (OM) and a high water content

The successive degradation of organic matter (OM) in the sediment

ENV-317 Meribiologia
…and not just brown.
Biologically and functionally diverse
Soft bottoms

Soft sediments:
Largest ecosystem of the world´s seafloor (70%)
3-D living environment (biotic interactions): Biodiversity and complexity
Secret-garden: microphytobenthos, organic matter
Sediment-seawater interface is permeable: fluxes (O2, nutrients)
Macrofauna: Foundation for food webs and ecological functioning
Microphytobenthos (secret garden)
Bioturbation: macrofauna reworking of seafloor can oxygenate (i.e. expose anoxic sediments to oxic seawater) and regulate
nutrient fluxes (A. Villnäs-07.02.20): think on earth-worms and compost.
D. Lohrer
macrofauna

Baltic seagrass meadow: Zostera marina
Mediterranean: Posidonia oceanica

Baltic: High diversity of aquatic plants (mixed seagrass)

Physical stress factors include:
UV light
waves effect
high fluctuation in temperature
dehydration salinity
The rocky intertidal is a challenging habitat
Biotic interactions, especially competition and predation, are more important in the lower parts of the tidal zone (more diverse).
Littorina-gastropods
Fucus spiralis
F. vesiculosus
F. serratus
Supratidal zone
Intertidal zone
Subtidal
Mostly
shelled
organisms
Many
soft organisms
and algae

Fucus vesiculosus
Mytilus trossulus x edulis
Rocky shore-Baltic Sea (no tides)
In the littoral, life on the shore is complicated with water fluctuations and winter. There are ephemeral filamentous algae (temporal, opportunistic, turf algae).
In the upper part of the sublittoral, there is a monospecific bladder wrack-zone (Fucus vesiculosus), with a variety of algal and animal communities. Below the red agal zone and the blue mussel reef
Turf algae
Cladophora glomerata
Furcellaria lumbricalis

Blue mussels dominate S Finland rocky reefs
3m
8m
15m
Photos: Mats Westerbom

Total 442 macroalgal species observed (Takolander et al. 2017 J. Sea Research_http://dx.doi.org/10.1016/j.seares.2017.03.007)
Fucoids most important habitat-forming species in Baltic Proper
F. vesiculosus is the main habitat-forming species (90% biomass, perennial)
Filamentous algae are major seasonal primary producers (summer peaks)
Eutrophication has caused extensive blooms of filamentous algae, and declines in abundance and depth penetration of fucoids (light, oxygen)
Algal detritus: organic material – connectivity (deep areas) – food – carbon sink?
Baltic Sea macroalgae: underwater forests
M. Westerbom

Fucoids in the Baltic: salinity controlled species
M. Westerbom

Dominate the benthic animal biomass
Few meters to 30 m (or too muddy)
Increases habitat complexity (biodiversity)
Filter feeder: excretion feeds algae and benthic macrofauna + faecal deposits (microbial degradation)
Key role in the coastal food-web
Blue mussel reefs
Mats Westerbom
Mats Westerbom
ENV-317 Meribiologia

Attard et al. 2019 Limnology & Oceanography Letters https://doi.org/10.1002/lol2.10107
Rodil et al. 2019. Ecosystems https://doi.org/10.1007/s10021-019-00427-0
Baltic example: benthic habitats
ENV-317 Meribiologia