COMMUNITY DYNAMICS OF AN INVADED ECOSYSTEM: PRELIMINARY INVESTIGATION OF A PTERYGOPLICHTHYS DISJUNCTIVUS INVASION

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1 COMMUNITY DYNAMICS OF AN INVADED ECOSYSTEM: PRELIMINARY INVESTIGATION OF A PTERYGOPLICHTHYS DISJUNCTIVUS INVASION Hill JM 1, Jones RW 2, Weyl OLF 3, Hill MP 1 1 Dept. Zoology &Entomology, Rhodes University, PO Box 94 Grahamstown, 6140, South Africa 2 Ezemvelo KZN Wildlife PO Box Meerensee 3901, South Africa 3 Centre for Invasion Biology, South African Institute for Aquatic Biodiversity, Private Bag 1015, Grahamstown 6140, South Africa

2 Pterygoplichthys disjunctivus Pterygoplichthys disjunctivus is native to South America (Brazil & Bolivia). Its the main nuisance species in the USA, Mexico and the Philippines Africa s first Loricariid invasion can be characterized as a self-sustaining population in the wild, with individuals surviving and reproducing a significant distance from their original point of introduction (D2) The only barrier to it becoming a fully invasive species (stage E ) is its inability to cross catchments without human assistance.

3 NSELENI RIVER SYSTEM 2000: 1 st report - Lake Mpangeni (Skelton & Weyl 2000) 2004: 1 st specimen record - Mhlathuze River (SAIAB voucher speciemen: SAIAB83643) 2006: 2 nd specimen record - Mposa River tributary of the Nseleni River (SAIAB voucher specimen: SAIAB83178) : Community donations and intensive sampling of Nseleni River system obtained 365 fish. Invasion history of P. disjunctivus in the Richards Bay area of KwaZulu-Natal, South Africa. Reproduced from Jones et al., 2013 Biol Invasions

4 ESTABLISHMENT Length frequency of P. disjunctivus collected (January 2011 May 2012) from the Nseleni River, South Africa. Reproduced from Jones et al., 2013 Biol Invasions

5 Pterygoplichthys disjunctivus Impacts of Loracarrid invasions are not well understood. Potential Ecological impacts include: Dietary resource competition with native fish direct predation on bottom-attached eggs of other fish bank destabilization due to tunnelling increased turbidity economic loss to local fisheries (Devick, 1989; Hoover et al., 2004; Nico et al., 2009a, 2009b, 2012, Wu et al. 2011) Aims: Assess the establishment of Pterygoplichthys disjunctivus in the Nseleni River System (see Jones et al Biol Invasions) Investigate direct competition for dietary resources between native fish species and the invader using niche width comparisons via stable isotope analysis (SIA). Investigate the diet of Pterygoplichthys disjunctivus via stable isotope analysis (SIA).

6 NICHE WIDTH COMPARISONS Fish Species Collected Fish Species n Pseudocrenilabrus philander 10 Clarias gariepinus 10 Barbus paludinosis 12 Glossogobius callidus 12 Marcusensis macrolepidotus 23 Oreochromis mossambicus 23 Pterygoplicthys distjuntivus 50 SIA Methods Defining an ecological niche based on its isotopic space (Bolnick et al. 2003; Bearhop et al., 2004; Newsome et al., 2007). Niche width comparisons using Stable Isotope Ellipses in R SIBER (Jackson et al. 2011, available at l)

7 NICHE WIDTH COMPARISONS Convex Hull Area Entire isotopic space occupied by a species. Very sensitive to sample size. (SEA c ) Core niche space Approx. 40% of the data 95% C. I. More robust to variation in sample size.

8 NICHE WIDTH COMPARISONS Mean ( ), 25%, 50%, 75% credible intervals. P. disjunctivus SEA > G. callidus, O. mossambicus, P. philander (p< 0.05) zooplankton omnivore benthic inverts chironimids diatoms/algae aquatic inverts detritus/biofilm

9 NICHE WIDTH COMPARISONS Schoener (1968) designated niche overlap criteria. Typically values of > 0.6 indicate significant dietary overlap. Invader VS B. paludinosus = 0.17 Invader VS C. gariepinus = 9.90E-17 Invader VS G. callidus = 0.49 Invader VS M. macrolepidotus = 0.48 P. disjunctivus = no significant dietary overlap with native fish species. Indirect competition? Invader VS O. mossambicus = 0.25 Invader VS P. philander = 8.95E-16

10 DIET So the invasive fish diet does not appear to overlap significantly with those of the native fish. Aims: Assess the establishment of Pterygoplichthys disjunctivus in the Nseleni River System (see Jones et al Biol Invasions) Investigate direct competition for dietary resources between native fish species and the invader using niche width comparisons via stable isotope analysis (SIA). Investigate the diet of Pterygoplichthys disjunctivus via stable isotope analysis (SIA).

11 DIET Stable Isotope SEAc Analyses Fish community Plant community (including riparian and floating vegetation and submerged aquatic species) POM Pelagic inverts Detritus Bayesian Mixing Models - SIAR (Parnell et al. 2008, available at Pterygoplicthys disjunctivus biplot δ 15 N = 5.13 δ 13 C = -0.1 (German & Miles 2010)

12 DIET Fractionation factors: δ 15 N = 5.13 δ 13 C = -0.1 (German & Miles 2010) All C4 plants were decomposing individuals rather than fresh living matter

13 PRELIMINARY FINDINGS Assess the establishment of Pterygoplichthys disjunctivus in the Nseleni River System (see Jones et al Biol Invasions) Africa s first Loricariid invasion can be characterized as a self-sustaining population in the wild, with individuals surviving and reproducing a significant distance from their original point of introduction (D2) Investigate direct competition for dietary resources between native fish species and the invader using niche width comparisons via stable isotope analysis (SIA). Very little direct dietary competition seems to be taking place between the invasive and native fish species.but indirect competition? Investigate the diet of Pterygoplichthys disjunctivus via stable isotope analysis (SIA). SIA mixing models suggest P. distjunctivus seems to feeding mostly on degrading C4 plants, predominantly Azolla sp. and Barrington racemosa in the Nseleni River system.

14 ACKNOWLEDGMENTS

15 ACKNOWLEDGMENTS Thanks to W. Kadye and M. Alexander for their timely rescues with R. Research & Postdoctoral Fellowship funded by the Working for Water Program ( Isotope Analyses completed at IsoEnvironmental, Dept. Rhodes University (

16 REFERENCES Armbuster JW, Page LM (2006) Rediscription of Pterygoplichthys punctatus and description of a new species of Pterygoplichthys (Siluriformes: Loricariidae). Neotrop Ichthyol 4: Blackburn TM, Pysˇek P, Bacher S, Carlton JT, Duncan RP, Jarosˇik V, Wilson JRU, Richardson DM (2011) A proposed unified framework for biological invasions. Trends Ecol Evol 26: Devick WS (1989) Disturbances and fluctuations in the Wahiawa Reservoir ecosystem. Honolulu: Hawaii Department of Land and Natural Resources, Division of Aquatic Resources. 30 p. Ferraris CJ (2007) Checklist of catfishes, recent and fossil (Osteichthyes, Siluriformes) and catalogue of siluriform primary types. Zootaxa 1418:1 628 Hoover JH, Kilgore KJ, Cofrancesco AF (2004) Suckermouth catfishes: Threats to aquatic ecosystems of the United States. Vicksburg: U.S. Army Corps of Engineers. Jones RW, Weyl O, Schwartz ER, Hill MP (2013). Using a unified invasion framework to characterize Africa s first loricariid catfish invasion. Biol Invasions DOI /s Nico LG, Loftus WF, Reid JP (2009a) Interactions between non-native armored suckermouth catfish (Loricariidae: Pterygoplichthys) and native Florida manatee (Trichechus manatus latirostris) in artesian springs. Aquat Invasions 4: Nico LG, Jelks HL, Tuten T (2009b) Non-native suckermouth armored catfishes in Florida: description of nest burrows and burrow colonies with assessment of shoreline conditions. Aquat Nuis Species Res Program Bull 9:1 30 Nico LG, Butt PL, Johnston GR, Jelks HL, Kail M, Walsh S (2012) Discovery of South American suckermouth armored catfishes (Loricariidae, Pterygoplichthys spp.) in the Santa Fe River drainage, Suwannee River basin, USA. Bioinvasions Rec 1: Schoener T (1968). The Anolis lizards of Bimini: resource partitioning in a complex fauna. Ecology, 49: Skelton P, Weyl O (2011) Fishes. In: Picker M, Griffiths C (eds) Alien and invasive animals, a South African perspective. Struik Nature, Cape Town, pp Wu L, Liu C, Lin S (2011) Identification of Exotic sailfin catfish species (Pterygoplichthys, Loricariidae) in Taiwan based on morphology and mtdna sequences. Zool Stud 50:

17 Extra - Pterygoplichthys disjunctivus Species were identified as Pterygioplichthys disjunctivus (Weber 1991) based on morphology and ventral surface coloration (Armbuster &Page 2006). BLAST searches done in Genbank and subsequent phylogenetic analysis revealed that sequences from Nseleni River specimens matched 100% (same haplotype) with individuals referred to as Pterygioplichthys disjunctivus & Pterygioplichthys pardalis (FISH-BOL project, described by Swartz et al. 2008) Results consistent with Wu et al. (2011), suggesting that there could be confusion with the identification of introduced loricariid populations and/or that hybridisation has occurred between closely related species (especially considering potential mixing and/or misidentification in the ornamental trade). Loricariid Nseleni River 2011, J. Hill /fishes/loricariidae/1index.html