Aquatic habitats, speciation, and zoogeography

Habitat suitability

Ontogenetic CyclicResident migrant migrant

Adapted from Able and Fahey 2010

High for all functions all of the time

Varies with size, age, or development

High for one function, low for another function

seasonal tidal diel

Freshwater habitats- lotic -

small streams

mature rivers

wetlands

Freshwater to marine Habitats - lentic

Ponds, small lakes

large lakes oceans

Profundalzone

Profundalzone

Estuarine environments

- challenging

Estuarine environment

1. Freshwater; usually temporary residents

2. Diadromous a. Found in large numbers as they travel through estuary b. Staging area (before moving upstream) e.g. salmon c. Nursery (e.g. shad)

3. True residents (entire life cycle in estuary)Few species in this category, e.g. white perch

4. Non-dependent marineCommonly found in lower reaches of estuary e.g. sculpins, flounders, surfperch

5. Dependent marine (a least 1 life-cycle stage)Spawning grounds or nurseries or feeding grounds for adults

Intertidal environment – very harsh crashing surf strong currents/tides daily exposure to air but, great spatial heterogeneity, abundance of food

Intertidal (littoral) environment 1. True residents: (dominant)

e.g. sculpins, blennies, clingfishes, gobies, gunnels

2. Partial residents (juveniles): (dominant)e.g. blennies, surfperches, labrids, some cottids, pholids

3. Tidal (= feeders) many species

4. Seasonal (= spawners) few species

Neritic zone (to ~200 m)Neritic zone(sub-littoral)

teratogenic sources of nutrientswithin the photic zone, highly productiveenergy from waves, tides, for mixing

Neritic zone

coral reefs, kelp forestshighly complex physical habitat, diverse physical nicheshighly speciose - about 40% of fish fauna – 6,000-8,000 spp

many species, few members, mostly smallmany specialized adaptations, particularly for feeding

Neritic zone

continental shelfarea out to 200 m deep - average 700 km widemud/silt substrate, not complex, little structural complexitymostly ground feeders - gadids, pleuronectidsfew species, very abundant, mostly large (up to 1m)

(euphotic)

(disphotic)

(aphotic)

Depth (m)

(euphotic)

(disphotic)

(aphotic)

Depth (m)

But what causes speciation??

Barriers to marine dispersal

continental drift – separated continental shelf areas

continents – absolute barriersisthmus of Panama, Suez, closed ~ 3.7mya

submerged geographic features – mountains, sills

temperature – tropics vs. temperate, currents

salinity barriers – polar regions

closed ~ 3.7 mya

closed ~ 3.7 mya

saline, cold

saline, cold

hot

23°C

2.5°C

14°C

2.5°C

225 MYA180 MYA

130 MYA 70 MYA

Freshwater fishes

Paleozoic MYACambrian 570Ordovician 505 first fishesSilurian 38Devonian 408 placoderms; “age of fishes”Carboniferous 360 hagfishes and lampreysPermian 286

MesozoicTriassic 245 Pangea convergence – paddlefish, sturgeonJurassic 208 Pangea split bowfins, gars, lungfishes Cretaceous 144 Esocidae, Umbridae, Salmonidae

Cenozoic Tertiary

Paleocene 65 Cyprinidae, Percidae, CatasomidaeEocene 58 Centrarchidae, IctaluridaeOligocene 38Miocene 24Pliocene 5

QuaternaryPleistocene 1.8 period of glaciationRecent

225 MYA180 MYA

130 MYA 70 MYA

Freshwater fishes

early Tertiary

early Tertiary

Pleistocene

Pleistocene

Mesozoic

Native ichthyofauna: Atlantic salmon European eel Sea lamprey Brown trout Sturgeon Arctic char

Current ichthyofauna European river lamprey European brook lamprey Allis shad Twait shad Common Dace Common minnow Gobio gobio Common roach Common rudd European chub Carp bream Stone Loach Tench Northern pike European smelt Irish pollan Three-spined stickleback Nine-spined stickleback European bullhead Norway bullhead