Aquatic habitats, speciation, and zoogeography

Habitat suitability OntogeneticCyclic Residentmigrantmigrant 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 lakesoceans

Profundal zone

Prof und al zon e

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 marine Commonly 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 nutrients within the photic zone, highly productive energy from waves, tides, for mixing

Neritic zone coral reefs, kelp forests highly complex physical habitat, diverse physical niches highly speciose - about 40% of fish fauna – 6,000-8,000 spp many species, few members, mostly small many specialized adaptations, particularly for feeding

Neritic zone continental shelf area out to 200 m deep - average 700 km wide mud/silt substrate, not complex, little structural complexity mostly ground feeders - gadids, pleuronectids few 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 barriers isthmus 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 hot

23°C 2.5°C 14°C 2.5°C

225 MYA 180 MYA 130 MYA 70 MYA

Freshwater fishes Paleozoic MYA Cambrian570 Ordovician505first fishes Silurian 38 Devonian408placoderms; “age of fishes” Carboniferous360hagfishes and lampreys Permian286 Mesozoic Triassic245 Pangea convergence – paddlefish, sturgeon Jurassic208Pangea split bowfins, gars, lungfishes Cretaceous144 Esocidae, Umbridae, Salmonidae Cenozoic Tertiary Paleocene65Cyprinidae, Percidae, Catasomidae Eocene58Centrarchidae, Ictaluridae Oligocene38 Miocene24 Pliocene 5 Quaternary Pleistocene 1.8period of glaciation Recent

225 MYA 180 MYA 130 MYA 70 MYA Freshwater fishes

early Tertiary 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